Positive displacement piston pump

Abstract

A positive displacement piston pump includes a cylinder having a working end, an inlet port, an outlet port and a working chamber bounded by the outlet port and the working end; a piston rotatably and reciprocably movable in the cylinder between a retracted position and an extended position, the piston including a free end having a recessed section alternately in fluid communication with the inlet port and the outlet port; a drive motor rotatably and reciprocably driving the piston in the cylinder; a yoke and ball and socket joint pivotally connecting the piston to the drive motor; a base having an upper surface with an elongated slot below the pivot point of the piston and an arcuate slot adjacent the opposite end of the cylinder; and first and second pivot pins secured to a swivel plate which is, in turn, secured to the cylinder through a vertical column, whereby the recessed section is positioned entirely in the working chamber when the piston is at the end of its pressure stroke, regardless of the angle between the piston and the drive motor.

What is claimed is: .[. 
     
       1.  A pump comprising: a cylinder including a working end, an inlet port, an outlet port and a working chamber bounded by said outlet port and said working end;   a piston rotatably and reciprocably movable in said cylinder between a retracted position and an extended position, said piston including a free end having a recessed section alternately in fluid communication with said inlet port and said outlet port;   means for pivotally connecting said piston to drive means which rotatably and reciprocably drives said piston in said cylinder; and   means for ensuring that said recessed section is positioned entirely in said working chamber when said piston is in said extended position, regardless of the angle between said piston and said drive means..]. .[.2. A pump according to claim 1; wherein said means for ensuring includes guide means for guiding said cylinder during pivotal movement of said piston with respect to said drive means to ensure that said recessed section is positioned entirely in said working chamber when said piston is in said extended position..]. .[.3. A pump according to claim 2; wherein said means for guiding includes base means having an arcuate slot with a radius of curvature generally transverse to said piston and at least one elongated slot extending in a direction generally transverse to said arcuate slot, and pin means for guiding said cylinder in said arcuate slot and said at least one elongated slot during pivotal movement of said   
     
     
        piston with respect to said drive means..]. 4. A pump according to claim .[.3.]. .Iadd.11; .Iaddend.wherein said means for ensuring includes swivel 
     
     
        plate means for connecting said pin means to said cylinder. 5. A pump according to claim .[.3.]. .Iadd.11; .Iaddend.wherein said piston includes a driven end opposite to said free end; and said means for pivotally connecting includes yoke means connected to said drive means and having a socket therein, arm means extending generally transverse from said driven end of said piston and a ball mounted on said arm means and mating with 
     
     
        said socket in a ball and socket arrangement. 6. A pump according to claim 5; wherein the arcuate slot is formed in a first plane of said base means, and the radius of curvature of said arcuate slot is centered substantially at the center of said ball when said arm means extends in a plane 
     
     
        substantially parallel to the first plane of said base means. 7. A pump according to claim 5; wherein said radius of curvature is formed on opposite sides of a center line and in a first plane of said base means, the radius of curvature of said arcuate slot on one side of said center line is centered substantially at the center of said ball when said arm means extends in a first direction in a plane substantially parallel with the first plane of said base means, and the radius of curvature of said arcuate slot on the opposite side of said center line is centered substantially at the center of said ball when said arm means extends in a 
     
     
        second, opposite direction in said plane. 8. A pump according to claim .[.3.]. .Iadd.11; .Iaddend.wherein said pin means includes a guide pin slidably positioned in said arcuate slot, at least one elongated slot and means for connecting said guide pin and said at least one pivot pin to said cylinder. .[.9. A pump according to claim 1; wherein said piston includes a driven end opposite to said free end; and said means for pivotally connecting includes yoke means connected to said drive means and having a socket therein, arm means extending generally transverse from said driven end of said piston and a ball mounted on said arm means and mating with said socket in a ball and socket arrangement..]. .[.10. A pump according to claim 2; wherein said guide means includes base means; swivel plate means mounted on said base means for supporting said cylinder; two elongated slots on one of said base means and said swivel plate means, and extending on opposite sides of and in the general direction of a center line of said pump; and two pin means on the other of said base means and said swivel plate means and extending in said two slots, respectively, for guiding said cylinder during pivotal movement of said piston with respect to said drive mens to ensure that said recessed section is positioned entirely in said working chamber when said piston is in said extended position..]. .Iadd.11. A pump comprising: a cylinder including a working end, an inlet port, an outlet port and a working chamber bounded by said outlet port and said working end;   a piston rotatably and reciprocably movable in said cylinder between a retracted position and an extended position, said piston including a free end having a recessed section alternately in fluid communication with said inlet port and said outlet port;   means for pivotally connecting said piston to drive means which rotatably and reciprocably drives said piston in said cylinder; and means for ensuring that said recessed section is positioned entirely in said working chamber when said piston is in said extended position, regardless of the angle between said piston and said drive means, said means for ensuring including guide means for guiding said cylinder during pivotal movement of said piston with respect to said drive means to ensure that said recessed section is positioned entirely in said working chamber when said piston is in said extended position, said means for guiding including base means having an arcuate slot with a radius of curvature generally transverse to said piston and at least one elongated slot extending in a direction generally transverse to said arcuate slot, and pin means for guiding said cylinder in said arcuate slot and said at least one elongated slot during pivotal movement of said piston with respect to said drive means. .Iaddend.