Pump Unit and Working Vehicle

Abstract

A pump unit for supply and discharge of hydraulic fluid into and from an actuator upon receiving driving power from a driving source is provided, in which said actuator is fluidly connected to said pump unit via a hydraulic circuit. The pump unit includes an input member operatively connected to the driving source, a first hydraulic pump body operatively connected to the input member, a pump case for accommodating the first hydraulic pump body and forming a hydraulic fluid sump, and a PTO unit accommodated within the pump case. The PTO unit includes a PTO shaft supported by the pump case so as to have an end extending outward from the pump case, and a clutch mechanism for selectively enabling and disabling transmission of driving power from the input member to the PTO shaft.

1 .- 24 . (canceled)  
   
   
       25 . A pump unit for supplying and suctioning hydraulic fluid into and from a motor unit upon receiving driving power from a driving source, the motor unit having a motor shaft for outputting a mechanical rotational power toward a driving wheel and a hydraulic motor body for rotating the motor shaft, and being accommodated outside the pump unit so as to be located away from the pump unit and fluidly connected to the pump unit via a hydraulic circuit, comprising: 
 an input member operatively connected to the driving source;    a first hydraulic pump body operatively connected to the input member, the first hydraulic pump body being of a variable displacement type so that a mechanical rotational power with variable speed can be outputted through the motor shaft;    a pump case for accommodating the first hydraulic pump body and forming a hydraulic fluid sump;    fluid connection ports disposed on an outside surface of the pump case for fluidly connecting the first hydraulic pump body with the hydraulic motor body of the motor unit; and    a PTO unit accommodated within the pump case the PTO unit comprising:    a PTO shaft supported by the pump case so as to have an end extending outward from the pump case; and    a clutch mechanism for selectively engaging or disengaging power transmission from the input member to the PTO shaft.    
   
   
       26 . A pump unit according to  claim 25 , wherein the pump case has an opening, wherein the pump case further comprises a center section connected to a pump case body so as to close the opening, while supporting the first hydraulic pump body on one of opposite sides thereof, wherein a part of the hydraulic circuit is formed in the center section.  
   
   
       27 . A pump unit according to  claim 26 , further comprising a charge pump unit for sucking hydraulic fluid from the hydraulic fluid sump and discharging the same to the hydraulic circuit, wherein the charge pump unit is operatively connected to the input member and supported on the other of the opposite sides of the center section.  
   
   
       28 . A pump unit according to  claim 27 , wherein the PTO unit further comprises a brake mechanism for releasing and applying braking force away from and to the PTO shaft in association with the operation of the clutch mechanism to engage and disengage power transmission from the input member to the PTO shaft, wherein the brake mechanism and the clutch mechanism are operated by hydraulic fluid discharged by the charge pump unit.  
   
   
       29 . A pump unit according to  claim 25 , wherein the PTO unit further comprises a brake mechanism for releasing and applying braking force away from and to the PTO shaft in association with the operation of the clutch mechanism to engage and disengage power transmission from the input member to the PTO shaft.  
   
   
       30 . A pump unit according to  claim 25 , further comprising an input shaft acting as the input member, and a first pump shaft that is operatively connected to the input shaft and drives the first hydraulic pump body.  
   
   
       31 . A pump unit according to  claim 30 , wherein the PTO shaft is arranged coaxially with the input shaft.  
   
   
       32 . A pump unit according to  claim 30 , wherein the PTO shaft has an axis, which is located at the same position as an axis of the input shaft in a vehicle width direction, and is arranged orthogonal to the axis of the input shaft.  
   
   
       33 . A pump unit according to  claim 25 , further comprising a first pump shaft that acts as the input member and drives the first hydraulic pump body.  
   
   
       34 . A pump unit according to  claim 33 , wherein the PTO shaft is arranged substantially parallel to the first pump shaft.  
   
   
       35 . A pump unit according to  claim 33 , wherein the PTO shaft is arranged substantially orthogonal to the first pump shaft.  
   
   
       36 . A pump unit for supplying and suctioning hydraulic fluid into and from first and second motor units upon receiving driving power from a driving source, each of the first and second motor units having a motor shaft for outputting a mechanical rotational power toward a corresponding driving wheel and a hydraulic motor body for rotating the motor shaft, and being accommodated outside the pump unit so as to be located away from the pump unit and fluidly connected to the pump unit via a hydraulic circuit, comprising: 
 an input member operatively connected to the driving source;    a first hydraulic pump body operatively connected to the input member, the first hydraulic pump body being of a variable displacement type so that a mechanical rotational power with variable speed can be outputted through the motor shaft of the first motor unit;    a second hydraulic pump body operatively connected to the input shaft, the second hydraulic pump body being of a variable displacement type so that a mechanical rotational power with variable speed can be outputted through the motor shaft of the second motor unit;    a pump case for accommodating the first and second hydraulic pump bodies and forming a hydraulic fluid sump, the pump case having an opening through which the first and second hydraulic pump bodies can pass, the pump case further comprising a center section connected to a pump case body so as to close the opening while supporting the first and second hydraulic pump bodies, the center section forming therein a part of the hydraulic circuit is formed in the center section;    first fluid connection ports being arranged on an outside surface of the center section for fluidly connecting the first hydraulic pump body with the hydraulic motor body of the first motor unit;    second fluid connection ports for fluidly connecting the second hydraulic pump body with the hydraulic motor body of the second motor unit, the second fluid connection ports being arranged at the same side of the center section as the first fluid connection ports; and    a PTO unit accommodated within the pump case the PTO unit comprising:    a PTO shaft supported by the pump case so as to have an end extending outward from the pump case; and    a clutch mechanism for selectively engaging or disengaging power transmission from the input member to the PTO shaft.    
   
   
       37 . A pump unit that receives driving power from a driving source and that supplies and suctions hydraulic fluid into and from a pair of right and left motor units for operatively and respectively driving a pair of driving wheels, comprising: 
 an input member operatively connected to the driving source;    a first hydraulic pump body that is operatively connected to the input member and that is of a variable displacement type;    a pump case for accommodating the first hydraulic pump body and forming a hydraulic fluid sump, the pump case being provided with fluid connection ports through which the first hydraulic pump body supplies and suctions hydraulic fluid on its outside surface; and    a PTO unit that is accommodated within the pump case, the PTO unit having a PTO shaft supported by the pump case so as to have a first end extending outward from the pump case, and a clutch mechanism for selectively engaging or disengaging power transmission from the input member to the PTO shaft,    wherein the PTO shaft mechanically and operatively drives a working machine, and    wherein the hydraulic fluid that the first pump body supplies and suctions trough the connection ports hydraulically drives the motor units disposed away from the pump unit.    
   
   
       38 . A pump unit that receives driving power from a driving source and that supplies and suctions hydraulic fluid into and from a pair of right and left motor units for operatively and respectively driving a pair of driving wheels, comprising: 
 an input member operatively connected to the driving source;    a first hydraulic pump body that is operatively connected to the input member and that is of a variable displacement type;    a second hydraulic pump body that is operatively connected to the input member and that is of a variable displacement type, the first and second hydraulic pumps being configured to be capable of controlling their volumes independently to each other;    a pump case for accommodating the first and second hydraulic pump bodies and forming a hydraulic fluid sump, the pump case being provided with first fluid connection ports through which the first hydraulic pump body supplies and suctions hydraulic fluid and second fluid connection ports through which the second hydraulic pump body supplies and suctions hydraulic fluid on its outside surface; and    a PTO unit accommodated within the pump case, the PTO unit having a PTO shaft supported by the pump case so as to have a first end extending outward from the pump case, and a clutch mechanism for selectively engaging or disengaging power transmission from the input member to the PTO shaft; wherein    the PTO shaft mechanically and operatively driving a working machine, and    the hydraulic fluid that the first pump body supplies and suctions trough the first connection ports hydraulically drives one of the motor units and the hydraulic fluid that the second pump body supplies and suctions through the second connection ports hydraulically drives the other of the motor units, the motor units being disposed away from the pump unit.    
   
   
       39 . A pump unit disposed away from right and left wheel motors and supplying hydraulic fluid to the wheel motors through conduits in order to hydraulically drive the wheel motors, comprising: 
 first and second hydraulic pump bodies respectively and independently supplying hydraulic fluid to the right and left wheel motors;    a pump case having one or more openings for inserting the first and second hydraulic pump bodies into the pump case;    one or more center sections closing the one or more openings while supporting the first and second hydraulic pump bodies, the one or more center sections being provided with plurality of fluid connection ports for fluidly connecting the first and second hydraulic pumps to the right and left wheel motors;    a first pump shaft driving the first pump body;    a second pump shaft driving the second pump body;    a PTO unit including a clutch mechanism that is accommodated within the pump case, and a PTO shaft that is operatively connected to a driven-side of the clutch mechanism and has a first end extending outward from the pump case; and    an input shaft that has a first end extending outward from the pump case to receive driving power, and a second end constantly and operatively connected to the first and second pump shafts and operatively connected the PTO shaft through the clutch mechanism.    
   
   
       40 . A pump unit according to  claim 39 , wherein the PTO shaft is arranged coaxially with the input shaft.  
   
   
       41 . A pump unit according to  claim 39 , wherein the PTO shaft is arranged orthogonally to the first and second pump shafts.  
   
   
       42 . A pump unit according to  claim 39 , wherein the pump case has the one opening, and the pump unit has the one center section closing the one opening while supporting both of the first and second hydraulic pump bodies.  
   
   
       43 . A pump unit according to  claim 39 , wherein the pump case has a partition wall that divides the inner space of the pump case into a space for accommodating the first and second pump bodies and a space for accommodating the PTO unit.  
   
   
       44 . A pump unit according to  claim 39 , wherein the clutch mechanism includes friction plates that engages power transmission from the input shaft to the PTO shaft when the hydraulic pressure is applied and disengages the power transmission when the hydraulic pressure is not applied, 
 the pump unit further comprises a charge pump acting as a hydraulic pressure source, and    the charge pump is supported by the pump case so as to be operatively driven by the input shaft.    
   
   
       45 . A pump unit according to  claim 44 , wherein the PTO unit further comprises a brake mechanism for applying braking force to the PTO shaft when the clutch mechanism disengages power transmission from the input shaft to the PTO shaft.