Pump device

Abstract

A pump device is configured so that a first drive shaft 20 for driving a first pump element E 1 and a second drive shaft 40 for driving a second pump element E 2 are connected through a third drive shaft 50 , and a first joint 51 and a second joint 52 are respectively connected between the first drive shaft 20 and the third drive shaft 50 , and between the second drive shaft 40 and the third drive shaft 50 , each of the first joint and the second joint being configured to permit a joining angle change or a change in an amount of eccentricity between the corresponding drive shafts. As a result of this configuration, a flexural deformation produced in the first and second drive shafts 20, 40 can be absorbed by means of the first and second joints 51, 52 , and thus it is possible to suppress the problem of the flexural deformation of one of the first and second drive shafts 20, 40 affecting the other.

1 . A pump device comprising:
 a pump housing having a first pump element housing part and a second pump element housing part formed therein;   a first pump element housed in the first pump element housing part and provided for suction and discharge of working fluid;   a second pump element housed in the second pump element housing part and provided for suction and discharge of working fluid;   a first drive shaft supported on the pump housing for rotationally driving the first pump element;   a second drive shaft supported on the pump housing for rotationally driving the second pump element;   a third drive shaft supported on the pump housing and located between the first drive shaft and the second drive shaft in an axial direction of the first drive shaft and provided for transmitting a rotational force between the first drive shaft and the second drive shaft;   a first joint located between the first drive shaft and the third drive shaft and provided for transmitting a rotational force between the first drive shaft and the third drive shaft and configured to permit a joint angle change or a change in an amount of eccentricity between the first drive shaft and the third drive shaft; and   a second joint located between the second drive shaft and the third drive shaft and provided for transmitting a rotational force between the second drive shaft and the third drive shaft and configured to permit a joint angle change or a change in an amount of eccentricity between the second drive shaft and the third drive shaft.   
     
     
         2 . A pump device as recited in  claim 1 , wherein:
 a bearing that supports the third drive shaft is provided.   
     
     
         3 . A pump device as recited in  claim 2 , wherein:
 the bearing is constructed by a first bearing located on a side of the first drive shaft in an axial direction of the third drive shaft and a second bearing located nearer to a side of the second drive shaft than the first bearing.   
     
     
         4 . A pump device as recited in  claim 3 , wherein:
 a first seal member is interposed between the first bearing and the second bearing in the axial direction of the third drive shaft, and a second seal member is interposed between the first seal member and the second bearing.   
     
     
         5 . A pump device as recited in  claim 4 , wherein:
 the pump housing has a communication passage opened at one end into a space defined between the pump housing and the third drive shaft and at the other end outwards, the one end of the communication passage being formed to open between the first seal member and the second seal member in the axial direction of the third drive shaft.   
     
     
         6 . A pump device as recited in  claim 3 , wherein:
 the first bearing is a ball bearing having a first inner ring, a first outer ring, and a plurality of balls confined between the first inner ring and the first outer ring;   the second bearing is a ball bearing having a second inner ring, a second outer ring, and a plurality of balls confined between the second inner ring and the second outer ring;   an inner periphery of the first inner ring is press-fitted to an outer peripheral surface of the third drive shaft; and   an outer periphery of the second outer ring is press-fitted to an inner peripheral surface of the pump housing.   
     
     
         7 . A pump device as recited in  claim 1 , wherein:
 the first pump element comprises:
 a rotor housed in the first pump element housing part and rotationally driven by the first drive shaft; 
 a plurality of vanes retractably accommodated in respective slots formed and cut in the rotor; and 
 an annular cam ring located in the first pump element housing part such that the cam ring can be displaced eccentrically to an axis of the first drive shaft and configured to define a plurality of pump chambers in conjunction with the rotor and the plurality of vanes, 
   wherein the cam ring is driven and controlled by a control means configured to control internal pressures in a first fluid-pressure chamber and a second fluid-pressure chamber, whose chambers are defined between the first pump element housing part and the cam ring and formed to oppose each other on opposite sides of the cam ring.   
     
     
         8 . A pump device as recited in  claim 7 , wherein:
 the pump housing comprises:
 a first pump housing having a cylindrical section formed on an outer peripheral side of the first drive shaft and configured to accommodate the first pump element and a bottom section provided at one axial end of the cylindrical section, the one axial end being opposite to the second drive shaft; and 
 a third pump housing located on a side of the second drive shaft in an axial direction of the cylindrical section and configured to accommodate the third drive shaft, 
   wherein the third drive shaft is supported by a pair of bearings located in the third pump housing.   
     
     
         9 . A pump device as recited in  claim 8 , wherein:
 one of the pair of bearings is inserted from one end of the third pump housing and the other of the pair of bearings is inserted from the other end of the third pump housing in the axial direction of the third drive shaft.   
     
     
         10 . A pump device as recited in  claim 7 , wherein:
 a discharge port, which is configured to open into a region such that a volume of each of the pump chambers decreases with rotation of the rotor, is located above a suction port, which is configured to open into a region such that the volume of each of the pump chambers increases with rotation of the rotor, in a vertical direction in a vehicle-mounted state.   
     
     
         11 . A pump device as recited in  claim 1 , wherein:
 the first joint has a first recessed portion which engages a protruding portion provided at one of opposing ends of the first drive shaft and the third drive shaft and a second recessed portion which engages a protruding portion provided at the other of the opposing ends of the first drive shaft and the third drive shaft; and   the second joint has a first recessed portion which engages a protruding portion provided at one of opposing ends of the second drive shaft and the third drive shaft and a second recessed portion which engages a protruding portion provided at the other of the opposing ends of the second drive shaft and the third drive shaft.   
     
     
         12 . A pump device comprising:
 a pump housing having a first pump element housing part and a second pump element housing part formed therein;   a first pump element housed in the first pump element housing part and provided for suction and discharge of working fluid;   a second pump element housed in the second pump element housing part and provided for suction and discharge of working fluid;   a first drive shaft supported on the pump housing for rotationally driving the first pump element;   a second drive shaft supported on the pump housing for rotationally driving the second pump element;   a joint located between the first drive shaft and the second drive shaft and provided for transmitting a rotational force between the first drive shaft and the second drive shaft and configured to permit a joint angle change or a change in an amount of eccentricity between the first drive shaft and the second drive shaft;   a bearing provided between the joint and the second pump element in an axial direction of the second drive shaft for supporting the second drive shaft; and   a pair of seal members provided between the bearing and the second pump element in the axial direction of the second drive shaft,   wherein the first pump element comprises:
 a rotor housed in the first pump element housing part and rotationally driven by the first drive shaft; 
 a plurality of vanes retractably accommodated in respective slots formed and cut in the rotor; and 
 an annular cam ring located in the first pump element housing part such that the cam ring can be displaced eccentrically to an axis of the first drive shaft and configured to define a plurality of pump chambers in conjunction with the rotor and the plurality of vanes.