Variable capacity piston pump

Abstract

A variable capacity piston pump including a piston portion of the control piston causing a pressing force to act along one direction by pressing a pressed portion of a swashplate from a cylinder block side to adjust an inclination of the swashplate between a maximum inclination and a minimum inclination, and a swashplate return spring biasing the pressed portion of the swashplate toward the cylinder block side of the sliding contact surface, wherein there is a positional relationship in which a vertical reference line passes between a first action position which is an action position of the pressing force when the inclination of the swashplate is the maximum inclination and a second action position which is an action position of the pressing force when the inclination of the swashplate is the minimum inclination.

1 . A variable capacity piston pump performing suction and discharge of a hydraulic fluid by reciprocation of a piston in a cylinder block rotating integrally with a rotating shaft, the stroke of the reciprocation of the piston depending on an inclination of a swashplate,
 wherein the swashplate includes a sliding contact surface contacting slidably with one end portion of the piston via a shoe, the swashplate being disposed to enable to turn about a turning center to change the inclination that defines the stroke of the piston,   the variable capacity piston pump comprising:   a pressing portion disposed on one side with respect to the sliding contact surface of the swashplate, the pressing portion causing a pressing force to act along one direction by pressing a pressed portion of the swashplate to adjust the inclination of the swashplate between a maximum inclination and a minimum inclination, wherein a discharge capacity of the hydraulic fluid is maximized at the maximum inclination and the discharge capacity of the hydraulic fluid is minimized at the minimum inclination, and   a swashplate return spring disposed on the other side with respect to the sliding contact surface of the swashplate, the swashplate return spring biasing the pressed portion of the swashplate toward the one side of the sliding contact surface,   wherein the pressed portion is capable of taking a first action position and a second action position, wherein the first action position is a position at which the pressing force of the pressing portion acts when the inclination of the swashplate is the maximum inclination and the second action position is a position at which the pressing force of the pressing portion acts when the inclination of the swashplate is the minimum inclination, and   wherein there is a positional relationship in which a vertical reference line passes between the first action position and the second action position, the vertical reference line being a straight line perpendicular to a parallel reference line and passing through the turning center of the swashplate, the parallel reference line being a straight line parallel to a direction in which the pressing force of the pressing portion acts and passing through the turning center of the swashplate.   
     
     
         2 . The variable capacity piston pump according to  claim 1 ,
 wherein there is a positional relationship in which the vertical reference line passes through a midpoint between the first action position and the second action position.   
     
     
         3 . The variable capacity piston pump according to  claim 1 ,
 wherein the pressing portion is disposed in parallel to the rotating shaft.