Pump control apparatus

Abstract

A pump control apparatus includes an actuator that varies a discharge capacity of a pump, and a regulator that regulates a control pressure led to the actuator. The regulator includes: a driving pressure port to which an average discharge pressure is led; a source pressure port to which a high pressure side discharge pressure is led; a signal pressure port to which a signal pressure is led; and a spool that regulates the control pressure using the high pressure side discharge pressure as a source pressure by moving upon reception of the average discharge pressure and the signal pressure. A driving pressure receiving surface that receives the average discharge pressure is formed inside the spool, and a signal pressure receiving surface that receives the signal pressure is formed in an outer peripheral step portion of the spool.

1 . A pump control apparatus for controlling a discharge capacity of a pump that discharges a working fluid through a plurality of discharge ports, comprising:
 an actuator that varies the discharge capacity of the pump; and   a regulator that regulates a control pressure led to the actuator, the regulator comprising:   a driving pressure port to which an average discharge pressure obtained by averaging respective discharge pressures of the working fluid discharged from the plurality of discharge ports is led;   a source pressure port to which a high pressure side discharge pressure, which is the highest discharge pressure of the working fluid discharged from the plurality of discharge ports, is led;   a signal pressure port to which a signal pressure is led; and   a spool that regulates the control pressure using the high pressure side discharge pressure as a source pressure by moving upon reception of the average discharge pressure and the signal pressure,   wherein a driving pressure receiving surface that receives the average discharge pressure is formed inside the spool, and   a signal pressure receiving surface that receives the signal pressure is formed in an outer peripheral step portion of the spool.   
     
     
         2 . The pump control apparatus as defined in  claim 1 , wherein the regulator further comprises:
 a driving pressure port connecting hole formed inside the spool so as to communicate with the driving pressure port;   an axial hole formed inside the spool and connected to the driving pressure port connecting hole; and   a pin that is inserted into the axial hole to be free to slide,   wherein a site on an inner wall surface of the driving pressure port connecting hole that opposes the pin constitutes the driving pressure receiving surface.   
     
     
         3 . The pump control apparatus as defined in  claim 1 , wherein the regulator further comprises:
 a second signal pressure port to which a second signal pressure, which is different from the signal pressure, is led; and   a second signal pressure port connecting hole formed inside the spool so as to communicate with the axial hole and the second signal pressure port,   wherein a pin outer peripheral step portion is formed in an intermediate portion of the pin, and   a site on an inner wall surface of the second signal pressure port connecting hole that opposes the pin outer peripheral step portion constitutes a second signal pressure receiving surface that receives the second signal pressure.   
     
     
         4 . The pump control apparatus as defined in  claim 1 , wherein, in a high load mode where a load of a drive source that drives the pump is high, the pump control apparatus increases the signal pressure received by the outer peripheral step portion of the spool such that the spool moves in a direction for increasing the discharge capacity of the pump, and
 in a low load mode where the load of the drive source is low, the pump control apparatus reduces the signal pressure received by the outer peripheral step portion of the spool such that the spool moves in a direction for reducing the discharge capacity of the pump.