Hydraulic pump unit

Abstract

There is provided a hydraulic pump unit of variable displacement type disposed away from a pair of hydraulic motor units which are capable of being independently arranged, the pump unit fluid-connected to the pair of hydraulic motor units so as to change the outputs of the pair of hydraulic motor units in both forward and reverse rotation directions. The pump unit includes a hydraulic pump body operatively rotated and driven by a driving source, a pump case surrounding the hydraulic pump body, a capacity adjusting mechanism for changing the capacity of the hydraulic pump body, and an actuator for operating the capacity adjusting mechanism. The actuator is controlled based on a manual operation signal corresponding to a manual operation amount.

1 . A hydraulic pump unit of variable displacement type disposed away from a pair of hydraulic motor units which are capable of being independently arranged, the pump unit fluid-connected to the pair of hydraulic motor units so as to change the outputs of the pair of hydraulic motor units in both forward and reverse rotation directions, comprising: 
 (a) a hydraulic pump body operatively rotated and driven by a driving source,    (b) a pump case surrounding the hydraulic pump body,    (c) a capacity adjusting mechanism for changing the capacity of the hydraulic pump body, and    (d) an actuator for operating the capacity adjusting mechanism, wherein the actuator is controlled based on a manual operation signal corresponding to a manual operation amount.    
   
   
       2 . The hydraulic pump unit according to  claim 1 , wherein the actuator is controlled based on a feedback signal corresponding to outputs of the pair of the hydraulic motor units, in addition to the manual operation signal.  
   
   
       3 . The hydraulic pump unit according to  claim 1 , wherein the hydraulic pump body includes first and second hydraulic pump bodies respectively and independently fluid-connected to the pair of hydraulic motor units; 
 (a) the capacity adjusting mechanism includes first and second capacity adjusting mechanisms respectively corresponding to the first and second hydraulic pump bodies; and    (b) the actuator includes first and second actuators respectively corresponding to the first and second capacity adjusting mechanisms.    
   
   
       4 . The hydraulic pump unit according to  claim 1 , wherein the pair of hydraulic motor units are fluid-connected to each other so as to form a closed circuit; and 
 (a) the hydraulic pump body includes a single hydraulic pump body for traveling fluid-connected to the closed circuit, and a hydraulic pump body fluid-connected to the other hydraulic actuator other than the pair of hydraulic motor units.    
   
   
       5 . The hydraulic pump unit according to  claim 1 , wherein the actuator is a hydraulic servomechanism that includes a servo piston operatively connected to the capacity adjusting mechanism and accommodated in a reciprocating manner within a piston accommodating chamber so as to divide the piston accommodating chamber into a regular rotation oil chamber and a reverse rotation oil chamber, a supply/discharge oil passage for supplying operating oil to and discharging it from the servo piston, and an electromagnetic valve for switching the supply/discharge oil passage.  
   
   
       6 . The hydraulic pump unit according to  claim 1 , wherein the actuator is an electronic motor operatively connected to the capacity adjusting mechanism.  
   
   
       7 . The hydraulic pump unit according to  claim 6 , wherein the electronic motor is connected to the capacity adjusting mechanism via a reduction gear mechanism.