Ejector and refrigerant cycle device with ejector

Abstract

An ejector for a refrigerant cycle device includes a nozzle portion for decompressing and expanding refrigerant flowing therein, and a body portion which accommodates the nozzle portion to support the nozzle portion at a support portion. The body portion has a refrigerant suction port from which refrigerant is drawn by a high-speed refrigerant flow jetted from a nozzle outlet of the nozzle portion. The nozzle portion is located in the body portion to have an ejector refrigerant passage through which the refrigerant flows. In the ejector, the nozzle portion is supported in the body portion to have the following relationship of 0<L/d≦14, in which L/d is a ratio of a length (L) between a downstream tip portion of the support portion and the nozzle outlet to a diameter (d) of the nozzle outlet.

1 . An ejector for a refrigerant cycle device, the ejector comprising:
 a nozzle portion for decompressing and expanding refrigerant flowing therein; and   a body portion which accommodates the nozzle portion to support the nozzle portion at a support portion, the body portion having a refrigerant suction port from which refrigerant is drawn by a high-speed refrigerant flow jetted from a nozzle outlet of the nozzle portion, wherein:   the nozzle portion is located in the body portion to have an ejector refrigerant passage through which the refrigerant jetted from the nozzle outlet of the nozzle portion and the refrigerant drawn from the refrigerant suction port flow; and   the nozzle portion is supported in the body portion to have the following relationship of 0<L/d≦14, in which L/d is a ratio of a length (L) between a downstream tip portion of the support portion and the nozzle outlet to a diameter (d) of the nozzle outlet.   
   
   
       2 . The ejector according to  claim 1 , wherein:
 the body portion has a mixing portion in which the refrigerant jetted from the nozzle outlet and the refrigerant drawn from the refrigerant suction port are mixed; and   the mixing portion has a wall thickness (t) and an inner diameter (D), and a ratio (t/D) of the wall thickness (t) to the inner diameter (D) is equal to or larger than 0.2.   
   
   
       3 . The ejector according to  claim 1 , wherein:
 the nozzle portion has a first part, a second part downstream from the first part in a refrigerant flow of the nozzle portion and positioned to correspond to an area of the refrigerant suction port, and a third part downstream from the second part in the refrigerant flow of the nozzle portion; and   the first part of the nozzle portion is supported by the body portion at the support portion.   
   
   
       4 . The ejector according to  claim 1 , wherein:
 the nozzle portion has a first part, a second part downstream from the first part in a refrigerant flow of the nozzle portion and positioned to correspond to an area of the refrigerant suction port, and a third part downstream from the second part in the refrigerant flow of the nozzle portion; and   the third part of the nozzle portion is supported by the body portion at the support portion.   
   
   
       5 . The ejector according to  claim 4 , wherein:
 the nozzle portion has a protrusion portion protruding from an outer wall surface of the third part of the nozzle portion toward the body portion; and   the protrusion portion of the nozzle portion contacts an inner wall of the body portion to form the support portion.   
   
   
       6 . The ejector according to  claim 4 , wherein:
 the body portion has a protrusion portion protruding from an inner wall of the body portion to the nozzle portion at a position corresponding to the third part of the nozzle portion; and   the protrusion portion of the body portion contacts an outer wall of the nozzle portion to form the support portion.   
   
   
       7 . The ejector according to  claim 4 , further comprising a support member located between an inner wall of the body portion and an outer wall of the third part of the nozzle portion; and
 the nozzle portion is supported in the body portion by the support member.   
   
   
       8 . The ejector according to  claim 1 , further comprising
 a driving portion for driving the nozzle portion so as to move the nozzle portion in an axial direction relative to the body portion, wherein   the nozzle portion is movable by the driving portion between a first state where an outer wall of the nozzle portion is spaced from an inner wall of the body portion such that the refrigerant drawn from the refrigerant suction port flows, and a second state where the outer wall of the nozzle portion contacts the inner wall of the body portion to be supported by the body portion at the support portion such that a refrigerant flow from the refrigerant suction port is closed.   
   
   
       9 . An ejector for a refrigerant cycle device, the ejector comprising:
 a nozzle portion having therein a nozzle passage in which high-pressure refrigerant before being decompressed flows, the nozzle portion having an approximately cylindrical outer wall portion and a nozzle outlet from which the refrigerant decompressed in the nozzle passage is jetted;   a body portion which accommodates the nozzle portion to define a suction passage, between the nozzle portion and the body portion, extending from the cylindrical outer wall portion to the nozzle outlet, the body portion having a refrigerant suction port that is opened radially outwardly of the cylindrical outer wall portion to communicate with the suction passage;   a first fixing member for connecting and fixing the nozzle portion to the body portion at a position upstream from the refrigerant suction port in a refrigerant flow of the nozzle passage; and   a second fixing member for connecting and fixing the nozzle portion to the body portion at a position downstream from the refrigerant suction port in the refrigerant flow of the nozzle passage.   
   
   
       10 . The ejector according to  claim 1 , wherein:
 the nozzle portion and the body portion are made of different members; and   the nozzle portion is fixed to the body portion by fastening or pressing means to be supported by the body portion.   
   
   
       11 . The ejector according to  claim 1 , wherein:
 the body portion has a mixing portion in which the refrigerant jetted from the nozzle outlet and the refrigerant drawn from the refrigerant suction port are mixed; and   the mixing portion has approximately a uniform wall thickness (t) and a uniform inner diameter (D), and a ratio t/D of the wall thickness (t) to the inner diameter (D) is equal to or larger than 1.   
   
   
       12 . The ejector according to  claim 1 , further comprising
 a cover member, which is located to cover an outer surface of the body portion at least in an area near the nozzle outlet,   wherein the cover member is made of a material to reduce at least one of vibration and noise caused in the body portion.   
   
   
       13 . The ejector according to  claim 1 , wherein:
 the body portion has a mixing portion in which the refrigerant jetted from the nozzle outlet and the refrigerant drawn from the refrigerant suction port are mixed, and a diffuser in which a passage sectional area is increased from the mixing portion toward downstream side; and   the body portion has a uniform outer wall surface at least in the mixing portion and the diffuser.   
   
   
       14 . The ejector according to  claim 13 , wherein:
 the mixing portion has approximately a uniform wall thickness; and   the diffuser has a wall thickness that is gradually reduced from the mixing portion toward downstream.   
   
   
       15 . The ejector according to  claim 13 , wherein the body portion has an approximately uniform cylindrical outer surface in an entire area. 
   
   
       16 . A refrigerant cycle device comprising:
 a compressor for sucking and compressing refrigerant;   a radiator for cooling high-pressure refrigerant discharged from the compressor;   the ejector according to  claim 1 , the nozzle portion of the ejector being located to decompress the refrigerant flowing from the radiator;   a first evaporator for evaporating the refrigerant flowing out of the ejector;   a branch passage branched from a refrigerant flow between the radiator and the nozzle portion of the ejector, and joined to the refrigerant suction port of the ejector;   a throttle unit located in the branch passage to decompress the refrigerant flowing into the branch passage;   a second evaporator located in the branch passage downstream from the throttle unit; and   a switching unit located in the branch passage to switch a refrigerant flow to the second evaporator.