Bellows Pump

Abstract

The present invention relates to, among bellows pumps for transporting a liquid with using a bellows which axially extends and contracts, a so-called internal-liquid type bellows pump in which an air chamber is formed outside a bellows and a liquid to be transported is sucked into the bellows. In order to prevent a pump bellows, a piston or coupling plate, and a shaft coupling them from being deviated from the same axis, prolong the life period of the pump, maintain the pump performance for a long term, and realize compactification and cost reduction of the pump, an external thread is formed on the outer face of one end side of the shaft, an engagement head is formed on the other end, a bottomed cylindrical shaft screwed portion which is projected from a center portion of the bottom into the pump bellows on the same axis, and which has an internal thread on an inner face is disposed in a bottomed cylindrical pump bellow, and the one end side of the shaft is directly coupled with a center portion of the pump bellows by thread joining.

1 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, and one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining.  
   
   
       2 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, a recess is disposed in a center portion of said pump body, and said shaft screwed portion has a length at which a tip end side of said shaft screwed portion is always fitted into said recess of said pump body.  
   
   
       3 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, said bellows pump comprises a piston which is to be coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a center hole through which said shaft is to be passed in a center portion is disposed in said piston, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to a portion of said shaft which is to be fitted into said center hole.  
   
   
       4 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, said bellows pump comprises a piston which is to be coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a center hole through which said shaft is to be passed in a center portion is disposed in said piston, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to said center hole into which said shaft is to be fitted.  
   
   
       5 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, said bellows pump comprises a piston which is to be coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a stepped center hole into which the other end of said shaft including said engagement head can be fitted is disposed in said piston, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to a portion of said shaft which is to be fitted into said center hole.  
   
   
       6 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, said bellows pump comprises a piston which is to be coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a stepped center hole into which the other end of said shaft including said engagement head can be fitted is disposed in said piston, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to said center hole into which said shaft is to be fitted.  
   
   
       7 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, said bellows pump comprises a coupling plate which is coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a center hole through which said shaft is to be passes is disposed in a center portion of said coupling plate, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to a portion of said shaft which is to be fitted into said center hole.  
   
   
       8 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, said bellows pump comprises a coupling plate which is coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a center hole through which said shaft is to be passed is disposed in a center portion of said coupling plate, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to said center hole into which said shaft is to be fitted.  
   
   
       9 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, a recess is disposed in a center portion of said pump body, said shaft screwed portion has a length at which a tip end side of said shaft screwed portion is always fitted into said recess of said pump body, said bellows pump comprises a piston which is to be coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a center hole through which said shaft is to be passed in a center portion is disposed in said piston, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to a portion of said shaft which is to be fitted into said center hole.  
   
   
       10 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, a recess is disposed in a center portion of said pump body, said shaft screwed portion has a length at which a tip end side of said shaft screwed portion is always fitted into said recess of said pump body, said bellows pump comprises a piston which is to be coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a center hole through which said shaft is to be passed in a center portion is disposed in said piston, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to said center hole into which said shaft is to be fitted.  
   
   
       11 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, a recess is disposed in a center portion of said pump body, said shaft screwed portion has a length at which a tip end side of said shaft screwed portion is always fitted into said recess of said pump body, said bellows pump comprises a piston which is to be coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a stepped center hole into which the other end of said shaft including said engagement head can be fitted is disposed in said piston, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to a portion of said shaft which is to be fitted into said center hole.  
   
   
       12 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, a recess is disposed in a center portion of said pump body, said shaft screwed portion has a length at which a tip end side of said shaft screwed portion is always fitted into said recess of said pump body, said bellows pump comprises a piston which is to be coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a stepped center hole into which the other end of said shaft including said engagement head can be fitted is disposed in said piston, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to said center hole into which said shaft is to be fitted.  
   
   
       13 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, a recess is disposed in a center portion of said pump body, said shaft screwed portion has a length at which a tip end side of said shaft screwed portion is always fitted into said recess of said pump body, said bellows pump comprises a coupling plate which is coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a center hole through which said shaft is to be passed is disposed in a center portion of said coupling plate, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to a portion of said shaft which is to be fitted into said center hole.  
   
   
       14 . A bellows pump comprising a pump bellows which axially extends and contracts, said bellows pump sucking a transported liquid by extension of said pump bellows from a suction port of a pump body into said pump bellows via a suction side check valve, and discharging the transported liquid by contraction of said pump bellows from a discharge port of said pump body via a discharge side check valve, wherein said pump comprises a shaft which has an external thread on an external face on one side, said pump bellows has a bottomed cylindrical shape, a bottomed cylindrical shaft screwed portion which is projected from a center portion of a bottom into said pump bellows on a same axis, and which has an internal thread on an inner face is disposed, one end side of said shaft can be directly coupled with a center portion of said pump bellows by thread joining, a recess is disposed in a center portion of said pump body, said shaft screwed portion has a length at which a tip end side of said shaft screwed portion is always fitted into said recess of said pump body, said bellows pump comprises a coupling plate which is coupled with said pump bellows by said shaft, an engagement head having a diameter which is larger than a diameter of said shaft is disposed in another end of said shaft, a center hole through which said shaft is to be passed is disposed in a center portion of said coupling plate, said shaft is fitted into said center hole in a contracting direction of said pump bellows, and an annular sealing member which is made of an elastic material is attached to said center hole into which said shaft is to be fitted.  
   
   
       15 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; a pump unit which is placed on one side of said pump body; and an accumulator unit which is placed on another side of said pump body, said pump unit comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pump bellows, said shaft, and said piston being integrally reciprocated by air which is alternately supplied to said pump air chamber and said second cylinder section, said pump bellows repeatedly extending and contracting so that, when said pump bellows extends, the transported liquid is sucked from a suction port of said pump body into said pump chamber via said suction side check valve, and, when said pump bellows contracts, the transported liquid is discharged from a discharge port of said pump body via said discharge side check valve, said accumulator unit comprising: a bottomed cylindrical accumulator bellows which is placed so that an open end portion is joined to the other side portion of said pump body to internally form an accumulator chamber for temporarily storing the transported liquid that is discharged from said pump chamber via said discharge side check valve, and which can axially extend and contract; and a bottomed cylindrical accumulator cylinder which is placed outside said accumulator bellows, which is opposed in the open end portion to said pump body across said open end portion of said accumulator bellows, and which forms an accumulator air chamber into which air is filled, outside said accumulator bellows, pulsation of the discharge pressure of said pump unit being absorbed by extension and contraction of said accumulator bellows, said pump bellows, said shaft, and said piston of said pump unit being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 3 .  
   
   
       16 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; a pump unit which is placed on one side of said pump body; and an accumulator unit which is placed on another side of said pump body, said pump unit comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pump bellows, said shaft, and said piston being integrally reciprocated by air which is alternately supplied to said pump air chamber and said second cylinder section, said pump bellows repeatedly extending and contracting so that, when said pump bellows extends, the transported liquid is sucked from a suction port of said pump body into said pump chamber via said suction side check valve, and, when said pump bellows contracts, the transported liquid is discharged from a discharge port of said pump body via said discharge side check valve, said accumulator unit comprising: a bottomed cylindrical accumulator bellows which is placed so that an open end portion is joined to the other side portion of said pump body to internally form an accumulator chamber for temporarily storing the transported liquid that is discharged from said pump chamber via said discharge side check valve, and which can axially extend and contract; and a bottomed cylindrical accumulator cylinder which is placed outside said accumulator bellows, which is opposed in the open end portion to said pump body across said open end portion of said accumulator bellows, and which forms an accumulator air chamber into which air is filled, outside said accumulator bellows, pulsation of the discharge pressure of said pump unit being absorbed by extension and contraction of said accumulator bellows, said pump bellows, said shaft, and said piston of said pump unit being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 4 .  
   
   
       17 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; a pump unit which is placed on one side of said pump body; and an accumulator unit which is placed on another side of said pump body, said pump unit comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pump bellows, said shaft, and said piston being integrally reciprocated by air which is alternately supplied to said pump air chamber and said second cylinder section, said pump bellows repeatedly extending and contracting so that, when said pump bellows extends, the transported liquid is sucked from a suction port of said pump body into said pump chamber via said suction side check valve, and, when said pump bellows contracts, the transported liquid is discharged from a discharge port of said pump body via said discharge side check valve, said accumulator unit comprising: a bottomed cylindrical accumulator bellows which is placed so that an open end portion is joined to the other side portion of said pump body to internally form an accumulator chamber for temporarily storing the transported liquid that is discharged from said pump chamber via said discharge side check valve, and which can axially extend and contract; and a bottomed cylindrical accumulator cylinder which is placed outside said accumulator bellows, which is opposed in the open end portion to said pump body across said open end portion of said accumulator bellows, and which forms an accumulator air chamber into which air is filled, outside said accumulator bellows, pulsation of the discharge pressure of said pump unit being absorbed by extension and contraction of said accumulator bellows, said pump bellows, said shaft, and said piston of said pump unit being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 5 .  
   
   
       18 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; a pump unit which is placed on one side of said pump body; and an accumulator unit which is placed on another side of said pump body, said pump unit comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pump bellows, said shaft, and said piston being integrally reciprocated by air which is alternately supplied to said pump air chamber and said second cylinder section, said pump bellows repeatedly extending and contracting so that, when said pump bellows extends, the transported liquid is sucked from a suction port of said pump body into said pump chamber via said suction side check valve, and, when said pump bellows contracts, the transported liquid is discharged from a discharge port of said pump body via said discharge side check valve, said accumulator unit comprising: a bottomed cylindrical accumulator bellows which is placed so that an open end portion is joined to the other side portion of said pump body to internally form an accumulator chamber for temporarily storing the transported liquid that is discharged from said pump chamber via said discharge side check valve, and which can axially extend and contract; and a bottomed cylindrical accumulator cylinder which is placed outside said accumulator bellows, which is opposed in the open end portion to said pump body across said open end portion of said accumulator bellows, and which forms an accumulator air chamber into which air is filled, outside said accumulator bellows, pulsation of the discharge pressure of said pump unit being absorbed by extension and contraction of said accumulator bellows, said pump bellows, said shaft, and said piston of said pump unit being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 6 .  
   
   
       19 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; a pump unit which is placed on one side of said pump body; and an accumulator unit which is placed on another side of said pump body, said pump unit comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pump bellows, said shaft, and said piston being integrally reciprocated by air which is alternately supplied to said pump air chamber and said second cylinder section, said pump bellows repeatedly extending and contracting so that, when said pump bellows extends, the transported liquid is sucked from a suction port of said pump body into said pump chamber via said suction side check valve, and, when said pump bellows contracts, the transported liquid is discharged from a discharge port of said pump body via said discharge side check valve, said accumulator unit comprising: a bottomed cylindrical accumulator bellows which is placed so that an open end portion is joined to the other side portion of said pump body to internally form an accumulator chamber for temporarily storing the transported liquid that is discharged from said pump chamber via said discharge side check valve, and which can axially extend and contract; and a bottomed cylindrical accumulator cylinder which is placed outside said accumulator bellows, which is opposed in the open end portion to said pump body across said open end portion of said accumulator bellows, and which forms an accumulator air chamber into which air is filled, outside said accumulator bellows, pulsation of the discharge pressure of said pump unit being absorbed by extension and contraction of said accumulator bellows, said pump bellows, said shaft, and said piston of said pump unit being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 9 .  
   
   
       20 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; a pump unit which is placed on one side of said pump body; and an accumulator unit which is placed on another side of said pump body, said pump unit comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pump bellows, said shaft, and said piston being integrally reciprocated by air which is alternately supplied to said pump air chamber and said second cylinder section, said pump bellows repeatedly extending and contracting so that, when said pump bellows extends, the transported liquid is sucked from a suction port of said pump body into said pump chamber via said suction side check valve, and, when said pump bellows contracts, the transported liquid is discharged from a discharge port of said pump body via said discharge side check valve, said accumulator unit comprising: a bottomed cylindrical accumulator bellows which is placed so that an open end portion is joined to the other side portion of said pump body to internally form an accumulator chamber for temporarily storing the transported liquid that is discharged from said pump chamber via said discharge side check valve, and which can axially extend and contract; and a bottomed cylindrical accumulator cylinder which is placed outside said accumulator bellows, which is opposed in the open end portion to said pump body across said open end portion of said accumulator bellows, and which forms an accumulator air chamber into which air is filled, outside said accumulator bellows, pulsation of the discharge pressure of said pump unit being absorbed by extension and contraction of said accumulator bellows, said pump bellows, said shaft, and said piston of said pump unit being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 10 .  
   
   
       21 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; a pump unit which is placed on one side of said pump body; and an accumulator unit which is placed on another side of said pump body, said pump unit comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pump bellows, said shaft, and said piston being integrally reciprocated by air which is alternately supplied to said pump air chamber and said second cylinder section, said pump bellows repeatedly extending and contracting so that, when said pump bellows extends, the transported liquid is sucked from a suction port of said pump body into said pump chamber via said suction side check valve, and, when said pump bellows contracts, the transported liquid is discharged from a discharge port of said pump body via said discharge side check valve, said accumulator unit comprising: a bottomed cylindrical accumulator bellows which is placed so that an open end portion is joined to the other side portion of said pump body to internally form an accumulator chamber for temporarily storing the transported liquid that is discharged from said pump chamber via said discharge side check valve, and which can axially extend and contract; and a bottomed cylindrical accumulator cylinder which is placed outside said accumulator bellows, which is opposed in the open end portion to said pump body across said open end portion of said accumulator bellows, and which forms an accumulator air chamber into which air is filled, outside said accumulator bellows, pulsation of the discharge pressure of said pump unit being absorbed by extension and contraction of said accumulator bellows, said pump bellows, said shaft, and said piston of said pump unit being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 11 .  
   
   
       22 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; a pump unit which is placed on one side of said pump body; and an accumulator unit which is placed on another side of said pump body, said pump unit comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pump bellows, said shaft, and said piston being integrally reciprocated by air which is alternately supplied to said pump air chamber and said second cylinder section, said pump bellows repeatedly extending and contracting so that, when said pump bellows extends, the transported liquid is sucked from a suction port of said pump body into said pump chamber via said suction side check valve, and, when said pump bellows contracts, the transported liquid is discharged from a discharge port of said pump body via said discharge side check valve, said accumulator unit comprising: a bottomed cylindrical accumulator bellows which is placed so that an open end portion is joined to the other side portion of said pump body to internally form an accumulator chamber for temporarily storing the transported liquid that is discharged from said pump chamber via said discharge side check valve, and which can axially extend and contract; and a bottomed cylindrical accumulator cylinder which is placed outside said accumulator bellows, which is opposed in the open end portion to said pump body across said open end portion of said accumulator bellows, and which forms an accumulator air chamber into which air is filled, outside said accumulator bellows, pulsation of the discharge pressure of said pump unit being absorbed by extension and contraction of said accumulator bellows, said pump bellows, said shaft, and said piston of said pump unit being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 12 .  
   
   
       23 . A bellows pump according to  claim 15 , wherein, in addition to said pump body, said pump bellows, said suction side check valve, said discharge side check valve, and said accumulator bellows which are liquid-contacting components of said pump unit and said accumulator unit, said pump cylinder, said piston, said shaft, and said accumulator cylinder which are non-liquid-contacting components are made of a resin material.  
   
   
       24 . A bellows pump according to  claim 16 , wherein, in addition to said pump body, said pump bellows, said suction side check valve, said discharge side check valve, and said accumulator bellows which are liquid-contacting components of said pump unit and said accumulator unit, said pump cylinder, said piston, said shaft, and said accumulator cylinder which are non-liquid-contacting components are made of a resin material.  
   
   
       25 . A bellows pump according to  claim 17 , wherein, in addition to said pump body, said pump bellows, said suction side check valve, said discharge side check valve, and said accumulator bellows which are liquid-contacting components of said pump unit and said accumulator unit, said pump cylinder, said piston, said shaft, and said accumulator cylinder which are non-liquid-contacting components are made of a resin material.  
   
   
       26 . A bellows pump according to  claim 18 , wherein, in addition to said pump body, said pump bellows, said suction side check valve, said discharge side check valve, and said accumulator bellows which are liquid-contacting components of said pump unit and said accumulator unit, said pump cylinder, said piston, said shaft, and said accumulator cylinder which are non-liquid-contacting components are made of a resin material.  
   
   
       27 . A bellows pump according to  claim 19 , wherein, in addition to said pump body, said pump bellows, said suction side check valve, said discharge side check valve, and said accumulator bellows which are liquid-contacting components of said pump unit and said accumulator unit, said pump cylinder, said piston, said shaft, and said accumulator cylinder which are non-liquid-contacting components are made of a resin material.  
   
   
       28 . A bellows pump according to  claim 20 , wherein, in addition to said pump body, said pump bellows, said suction side check valve, said discharge side check valve, and said accumulator bellows which are liquid-contacting components of said pump unit and said accumulator unit, said pump cylinder, said piston, said shaft, and said accumulator cylinder which are non-liquid-contacting components are made of a resin material.  
   
   
       29 . A bellows pump according to  claim 21 , wherein, in addition to said pump body, said pump bellows, said suction side check valve, said discharge side check valve, and said accumulator bellows which are liquid-contacting components of said pump unit and said accumulator unit, said pump cylinder, said piston, said shaft, and said accumulator cylinder which are non-liquid-contacting components are made of a resin material.  
   
   
       30 . A bellows pump according to  claim 22 , wherein, in addition to said pump body, said pump bellows, said suction side check valve, said discharge side check valve, and said accumulator bellows which are liquid-contacting components of said pump unit and said accumulator unit, said pump cylinder, said piston, said shaft, and said accumulator cylinder which are non-liquid-contacting components are made of a resin material.  
   
   
       31 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pistons of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said pistons of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said second cylinder sections of said pump units, said pump bellows of said pump units repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharges by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said piston of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 3 .  
   
   
       32 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pistons of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said pistons of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said second cylinder sections of said pump units, said pump bellows of said pump units repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharges by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said piston of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 4 .  
   
   
       33 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pistons of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said pistons of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said second cylinder sections of said pump units, said pump bellows of said pump units repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharges by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said piston of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 5 .  
   
   
       34 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pistons of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said pistons of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said second cylinder sections of said pump units, said pump bellows of said pump units repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharges by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said piston of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 6 .  
   
   
       35 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pistons of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said pistons of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said second cylinder sections of said pump units, said pump bellows of said pump units repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharges by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said piston of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 9 .  
   
   
       36 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pistons of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said pistons of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said second cylinder sections of said pump units, said pump bellows of said pump units repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharges by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said piston of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 10 .  
   
   
       37 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pistons of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said pistons of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said second cylinder sections of said pump units, said pump bellows of said pump units repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharges by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said piston of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 11 .  
   
   
       38 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across the open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows, and a second cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward a side opposite to said first cylinder section, and into which a piston is axially slidably fitted; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple said pump bellows with said piston; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said pistons of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said pistons of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said second cylinder sections of said pump units, said pump bellows of said pump units repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharges by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said piston of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said piston according to  claim 12 .  
   
   
       39 . A bellows pump according to  claim 31 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders, said pistons, and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       40 . A bellows pump according to  claim 32 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders, said pistons, and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       41 . A bellows pump according to  claim 33 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders, said pistons, and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       42 . A bellows pump according to  claim 34 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders, said pistons, and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       43 . A bellows pump according to  claim 35 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders, said pistons, and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       44 . A bellows pump according to  claim 36 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders, said pistons, and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       45 . A bellows pump according to  claim 37 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders, said pistons, and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       46 . A bellows pump according to  claim 38 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders, said pistons, and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       47 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, and a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across an open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple one end with said pump bellows; a coupling plate which is coupled with another end of said shaft; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said coupling plates of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said coupling plates of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said pump chambers of same pump units, said pump bellows repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharging by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said coupling plate of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said coupling plate according to  claim 7 .  
   
   
       48 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, and a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across an open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple one end with said pump bellows; a coupling plate which is coupled with another end of said shaft; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said coupling plates of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said coupling plates of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said pump chambers of same pump units, said pump bellows repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharging by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said coupling plate of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said coupling plate according to  claim 8 .  
   
   
       49 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, and a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across an open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple one end with said pump bellows; a coupling plate which is coupled with another end of said shaft; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said coupling plates of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said coupling plates of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said pump chambers of same pump units, said pump bellows repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharging by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said coupling plate of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said coupling plate according to  claim 13 .  
   
   
       50 . A bellows pump comprising: a pump body in which suction and discharge ports for a transported liquid are formed; 
 and a pair of pump units which are placed on both sides of said pump body, respectively, each of said pump units comprising: a bottomed cylindrical pump bellows which is placed so that an open end portion is joined to said pump body in one side portion of said pump body to internally form a pump chamber, and which can axially extend and contract; a pump cylinder configured by a cylinder head portion which is placed opposingly to said pump body in an axially outside of said pump bellows, and a first cylinder section which is projected on a same axis as said pump bellows from said cylinder head portion toward said pump body so as to internally accommodate said pump bellows, which is opposed in an open end portion to said pump body across an open end portion of said pump bellows, and which cooperates with said cylinder head portion to form a pump air chamber outside said pump bellows; a shaft which slidably passes through a center portion of said cylinder head portion in an axial direction to couple one end with said pump bellows; a coupling plate which is coupled with another end of said shaft; and suction side and discharge side check valves which are attached to said pump body in said pump chamber, said coupling plates of said pump units being coupled together, suction valve ports of said suction side check valves of said pump units being communicatingly connected to said suction port of said pump body, discharge valve ports of said discharge side check valves being communicatingly connected to said discharge port, said pump bellows, said shafts, and said coupling plates of said pump units being integrally reciprocated in a same direction by air which is alternately supplied to said pump chambers of same pump units, said pump bellows repeatedly extending and contracting in an alternate manner so that, when one of said pump units sucks by extension of said pump bellow the transported liquid from said suction port of said pump body into said pump chamber via said suction side check valve, said other pump unit discharging by contraction of said pump bellow the transported liquid from said discharge port of said pump body via said discharge side check valve, said pump bellows, said shaft, and said coupling plate of each of said pump units being coupled together by said coupling structure of said pump bellows, said shaft, and said coupling plate according to  claim 14 .    
   
   
       51 . A bellows pump according to  claim 47 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       52 . A bellows pump according to  claim 48 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       53 . A bellows pump according to  claim 49 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders and said shafts which are non-liquid-contacting components are made of a resin material.  
   
   
       54 . A bellows pump according to  claim 50 , wherein, in addition to said pump bodies, said pump bellows, said suction side check valves, and said discharge side check valves which are liquid-contacting components of said pump units, said pump cylinders and said shafts which are non-liquid-contacting components are made of a resin material.