Variable displacement vane pump with variable target regulator

• US 6,896,489 B2
• Filed: 12/12/2001
• Issued: 05/24/2005
• Est. Priority Date: 12/12/2000
• Status: Active Grant

• Current Assignee: Gestion Proche, Inc., SLW Automotive, Inc.
• Original Assignee: BorgWarner Incorporated
• Inventors: Hunter, Douglas G., Niemiec, Albin J.
• Primary Examiner(s): FREAY, CHARLES GRANT
• Application Number:
  US10/021,566
• Publication Number:
  US 20020114708A1
• Time in Patent Office: 1,259 Days
• Field of Search: 418/25, 418/26, 418/30, 418/31, 418/15, 418/16, 418/21, 418/22, 418/23, 418/24, 418/27, 418/28, 417/220, 417/307, 417/308, 417/309, 417/310, 417/311
• US Class Current: 417/220
• CPC Class Codes: F01C 21/0836 comprising guiding means, e.g. cams, rollers
• CPC Class Codes: F01C 21/0863 the fluid being the working fluid
• CPC Class Codes: F04C 14/226 by pivoting the cam around an eccentric axis
• CPC Class Codes: F04C 14/26 using bypass channels

Abstract

A variable displacement vane-type fluid pump is provided which permits improved regulation of the pump discharge such that the pump can meet the various requirements of lubrication for internal combustion engines at all speeds with minimized use of power. Of course, the vane pump may also be utilized in a wide range of power transmission and other fluid distribution applications. The variable displacement vane pump of the invention may utilize both hydrostatic and mechanical assistance in radially positioning its vanes to ensure efficient and quiet operation of the pump and to facilitate priming of the pump. The vane pump of the invention may also use both hydrostatic and mechanical actuators to control the position of its containment ring or eccentric ring and hence, regulate the output of the pump. According to yet another aspect of the present invention, to prevent inlet flow restriction or cavitation, a valve may be provided to permit some of the pump outlet or discharge flow to bleed into the pump inlet to provide needed velocity and energy to the fluid flow into the pump inlet.

Claims

1. A variable displacement vane pump, comprising:

a housing defining a chamber, a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the housing under pressure;

a containment ring or eccentric ring pivotally carried by the housing for movement between a first position and a second position and defining an opening with an internal surface;

a rotor carried by the housing for rotation relative to the internal surface and having a plurality of slots extending inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with each vane slidably received in a slot in the rotor;

a first actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a first direction;

a second actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a second direction;

wherein control and positioning of the first and second actuators are a function of a combination of a first pressure signal and a second pressure signal taken from discrete locations separated by a degree of inherent hydraulic resistance in a downstream fluid circuit;

an area defining a fluid chamber formed between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator; and

a control valve responsive to the differential between the first pressure signal and the second pressure signal to selectively apply, based on engine conditions, application of fluid under pressure to either the first or second actuator based on engine conditions.

2. The pump of claim 1 wherein the first actuator is a piston slidably carried by the housing.

3. The variable displacement vane pump of claim 1 wherein said second direction is in a direction opposite of the first direction.

4. The pump of claim 1 wherein the second actuator is a piston slidably carried by the housing.

5. The pump of claim 1 wherein the first actuator includes a spring that in yielding biases the containment ring or eccentric ring in the first direction.

6. The pump of claim 1 which also comprises a seal between the containment ring or eccentric ring and the housing.

7. The pump of claim 1 which also comprises another fluid chamber defined at least in part by seal with fluid under pressure in the another fluid chamber defining the second actuator.

8. The pump of claim 1 which also comprises a pivot pin about which the containment ring or eccentric ring pivots, the pivot pin defining a pivot axis of the containment ring or eccentric ring which is offset from the axis of the rotor by about one-half the maximum eccentricity of the containment ring or eccentric ring relative to the rotor.

9. The pump of claim 1 which also comprises an inlet flow valve responsive to a fluid pressure signal above a threshold pressure to permit a portion of fluid discharged from the pump outlet to flow into the pump inlet during at least some fluid flow conditions.

10. The pump of claim 9 wherein the inlet flow valve is yieldably biased to a position preventing fluid discharged from the pump outlet to flow into the inlet of the pump and is displaced by a sufficiently high fluid pressure signal to a position permitting fluid discharged from the pump outlet to flow into the pump inlet.

11. The pump of claim 1 which also comprises a vane extension member carried by the housing and engageable with the vanes during at least certain positions of the rotor to ensure that at least two vanes extend outwardly from the exterior of the rotor at all times.

12. The pump of claim 11 wherein the vane extension member is a ring carried by the rotor to engage at least two vanes at all times.

13. The pump of claim 1 wherein the slots on the rotor extend radially inwardly of the rotor.

14. The pump of claim 1 wherein the seal is defined by direct contact between the containment ring or eccentric ring and the housing.

15. The pump of claim 1 wherein the seal is carried by the containment ring or eccentric ring.

16. The pump of claim 1 wherein the seal is carried on the housing.

17. The pump of claim 10 wherein fluid under pressure is communicated with the slots in the rotor to bias the vanes into contact with the cam surface.

18. The pump of claim 11 wherein the vane extension member further comprises a ring portion for engaging the two vanes and oil pressure acting on the vanes for extending the vanes outwardly.

19. The pump of claim 1 which also comprises an exhaust opening in the housing through which fluid in the fluid chamber is discharged under certain fluid flow conditions and wherein the control valve controls fluid flow from the fluid chamber through the exhaust opening in response to certain fluid pressures of said first and second pilot pressures.

20. The pump of claim 1 wherein the vanes have leading and trailing faces and the slots in the rotor are slightly wider than the vanes received in said slots so that a fluid film forms between the rotor and the leading and trailing faces of each vane.

21. The pump of claim 20 further comprises a seal between a vane and the rotor to restrict fluid flow between them.

22. The pump of claim 21 wherein the seal is formed by contact between the vane and rotor.

23. The pump of claim 10 wherein the inlet flow valve is biased by a spring.

24. The pump of claim 23 wherein the inlet flow valve is further biased by a pilot pressure signal.

25. A variable displacement vane-type fluid pump, comprising:

a housing defining a pump inlet through which fluid enters the pump, a pump outlet from which fluid is discharged under pressure and a fluid chamber between the pump inlet and pump outlet;

a containment ring or eccentric ring pivotally carried by the housing within the fluid chamber for movement between a first position and a second position, the containment ring or eccentric ring having an interior opening with an internal surface;

a rotor carried by the housing at least in part in the interior opening of the containment ring or eccentric ring, driven for rotation relative to the internal surface and having a plurality of slots extending radially inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with a vane slidably received in each slot in the rotor;

a first actuator responsive to a first fluid pressure and operable to pivot the containment ring or eccentric ring toward its first position;

a second actuator responsive to a second fluid pressure and operable to pivot the containment ring or eccentric ring toward its second position;

a control valve responsive to the differential between a first pressure signal and a second pressure signal to selectively apply, based on engine conditions, application of fluid under pressure to either the first or second actuator based on engine conditions;

wherein control and positioning of the first and second actuators are a function of a combination of the first pressure signal and the second pressure signal taken from discrete locations separated by a degree of inherent hydraulic resistance in a downstream fluid; and

an area defining fluid chamber form d between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator.

26. A variable displacement vane-type fluid pump, comprising:

a housing defining a pump inlet through which fluid enters the pump, a pump outlet from which fluid is discharged under pressure and a fluid chamber between the pump inlet and pump outlet;

a containment ring or eccentric ring pivotally carried by the housing for movement between a first position and a second position and defining an internal surface;

a rotor carried by the housing in the fluid chamber for rotation relative to the internal surface and having a plurality of slots extending inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with a vane slidably received in each slot in the rotor;

a first actuator responsive to a first control pressure and operable to pivot the containment ring or eccentric ring in a first direction;

a second actuator responsive to a second control pressure and operable to pivot the containment ring or eccentric ring in a second direction;

a control valve responsive to a control pilot pressure to control application of the first fluid pressure to the first actuator, and responsive to a second control pressure to control application of the second fluid pressure to the second actuator; and

a vane extension member carried by the housing and engageable with the vanes during at least certain positions of the rotor to ensure that at least one vane extends outwardly from the exterior of the rotor at all times.

27. The variable displacement vane-type fluid pump of claim 26 wherein the first actuator is a chamber formed between a portion of the containment ring and a portion of the housing.

28. A variable displacement vane-type fluid pump, comprising:

a housing defining a pump inlet through which fluid enters the pump, a pump outlet from which fluid is discharged under pressure and a fluid chamber between the pump inlet and pump outlet;

a containment ring or eccentric ring pivotally carried by the housing within the fluid chamber for movement between a first position and a second position, the containment ring or eccentric ring having an interior opening with an internal surface;

a rotor carried by the housing at least in part in the interior opening of the containment ring or eccentric ring, driven for rotation relative to the internal surface and having a plurality of slots extending radially inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with a vane slidably received in each slot in the rotor;

a first actuator responsive to a first control pressure and operable to pivot the containment ring or eccentric ring toward its first position;

a second actuator responsive to a second control pressure and operable to pivot the containment ring or eccentric ring toward its second position;

a control circuit responsive to engine conditions for providing a variable targeting of pump output wherein pressure from the oil circuit in the engine acts on the first actuator and pressure from the outlet acts on the second actuator for variable control of the containment ring in response to these conditions;

wherein control and positioning of the first and second actuators are a function of a combination of a first pressure signal and a second pressure signal taken from discrete locations separated by a degree of inherent hydraulic resistance in a downstream fluid circuit;

an area defining a fluid chamber formed between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator; and

a control valve responsive to the differential between the first pressure signal and the second pressure signal to selectively apply, based on engine conditions, application of fluid under pressure to either the first or second actuator based on engine conditions.

29. The variable displacement vane-type fluid pump of claim 28 wherein the control circuit includes an actuator operatively connected to one of the actuators for moving the containment ring in response to the control pressures.

30. A variable displacement vane pump, comprising:

a housing defining a chamber, a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the housing under pressure;

a containment ring or eccentric ring pivotally carried by the housing for movement between a first position and a second position and defining an opening with an internal surface;

a rotor carried by the housing for rotation relative to the internal surface and having a plurality of slots extending inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with each vane slidably received in a slot in the rotor;

a first actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a first direction;

a second actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a second direction;

wherein the first and second actuators are fluid acting directly on the containment ring;

wherein control and positioning of the first and second actuators are a function of a combination of a first pressure signal and a second pressure signal taken from discrete locations separated by a degree of inherent hydraulic resistance in a downstream fluid circuit;

an area defining a fluid chamber formed between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator; and

a control valve responsive to the differential between the first pressure signal and the second pressure signal to selectively apply, based on engine conditions, application of fluid under pressure to either the first or second actuator based on engine conditions.

31. A variable displacement vane pump, comprising:

a housing defining a chamber, a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the housing under pressure;

a containment ring or eccentric ring pivotally carried by the housing for movement between a first position and a second position and defining an opening with an internal surface;

a rotor carried by the housing for rotation relative to the internal surface and having a plurality of slots extending inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with each vane slidably received in a slot in the rotor;

a first actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a first direction;

a second actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a second direction;

a seal between the containment ring or eccentric ring and the housing defining a fluid chamber between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator;

another fluid chamber defined at least in part by the seal with fluid under pressure in the another fluid chamber defining the second; and

a control valve responsive to the differential between the first pressure signal and the second pressure signal to selectively apply, based on engine conditions, application of fluid under pressure to either the first or second actuator based on engine conditions.

32. The pump of claim 31 which also comprises an inlet flow valve responsive to a fluid pressure signal above a threshold pressure to permit a portion of fluid discharged from the pump outlet to flow into the pump inlet during at least some fluid flow conditions.

33. The pump of claim 32 wherein the inlet flow valve is yieldably biased to a position preventing fluid discharged from the pump outlet to flow into the inlet of the pump and is displaced by a sufficiently high fluid pressure signal to a position permitting fluid discharged from the pump outlet to flow into the pump inlet.

34. The pump of claim 31 which also comprises a vane extension member carried by the housing and engageable with the vanes during at least certain positions of the rotor to ensure that at least two vanes extend outwardly from the exterior of the rotor at all times.

35. The pump of claim 34 wherein the vane extension member is a ring carried by the rotor to engage at least two vanes at all times.

36. The pump of claim 31 wherein the seal is carried by the containment ring or eccentric ring.

37. The pump of claim 33 wherein fluid under pressure is communicated with the slots in the rotor to bias the vanes into contact with the cam surface.

38. The pump of claim 37 wherein the vane extension member further comprises a ring portion for engaging the two rings and oil pressure acting on the vanes for extending the vane outwardly.

39. The pump of claim 33 wherein the inlet flow valve is biased by a spring.

40. The pump of claim 39 wherein the inlet flow valve is further biased by a pilot pressure signal.

41. A variable displacement vane pump, comprising:

a housing defining a chamber, a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the housing under pressure;

a containment ring or eccentric ring pivotally carried by the housing for movement between a first position and a second position and defining an opening with an internal surface;

a rotor carried by the housing for rotation relative to the internal surface and having a plurality of slots extending inwardly into the rotor from an exterior of the rotor,

a plurality of vanes carried by the rotor with each vane slidably received in a slot in the rotor;

a first actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a first direction;

a second actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a second direction; and

an inlet flow valve responsive to a fluid pressure signal above a threshold pressure to permit a portion of fluid discharged from the pump outlet to flow into the pump inlet during at least some fluid flow conditions.

42. The pump of claim 41 wherein the inlet flow valve is yieldably biased to a position preventing fluid discharged from the pump outlet to flow into the inlet of the pump and is displaced by a sufficiently high fluid pressure signal to a position permitting fluid discharged from the pump outlet to flow into the pump inlet.

43. The pump of claim 41 which also comprises a vane extension member carried by the housing and engageable with the vanes during at least certain positions of the rotor to ensure that at least two vanes extend outwardly from the exterior of the rotor at all times.

44. The pump of claim 43 wherein the vane extension member is a ring carried by the rotor to engage at least two vanes at all times.

45. The pump of claim 41 wherein the slots on the rotor extend radially inwardly of the rotor.

46. The pump of claim 42 wherein fluid under pressure is communicated with the slots in the rotor to bias the vanes into contact with the cam surface.

47. The pump of claim 43 wherein the vane extension member further comprises a ring portion for engaging the two rings and oil pressure acting on the vanes for extending the vane outwardly.

48. The pump of claim 41 wherein the vanes have leading and trailing faces and the slots in the rotor are slightly wider than the vanes received in the slots so that a fluid film forms between the rotor and the leading and trailing faces of each vane.

49. The pump of claim 48 further comprising a seal between a vane and the rotor to restrict fluid flow between them.

50. The pump of claim 49 wherein the seal is formed by contact between the vane and rotor.

51. The pump of claim 42 wherein the inlet flow valve is biased by a spring.

52. The pump of claim 51 wherein the inlet flow valve is further biased by a pilot pressure signal.

53. A variable displacement vane pump, comprising:

a housing defining a chamber, a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the housing under pressure;

a containment ring or eccentric ring pivotally carried by the housing for movement between a first position and a second position and defining an opening with an internal surface;

a rotor carried by the housing for rotation relative to the internal surface and having a plurality of slots extending inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with each vane slidably received in a slot in the rotor;

a first actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a first direction;

a second actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a second direction; and

a vane extension member carried by the housing and engageable with the vanes during at least certain positions of the rotor to ensure that at least two vanes extend outwardly from the exterior of the rotor at all times.

54. The pump of claim 53 wherein the vane extension member is a ring carried by the rotor to engage at least two vanes at all times.

55. The pump of claim 53 wherein the slots on the rotor extend radially inwardly of the rotor.

56. The pump of claim 53 wherein the vane extension member further comprises a ring portion for engaging the two rings and oil pressure acting on the vanes for extending the vane outwardly.

57. The pump of claim 53 wherein the vanes have leading and trailing faces and the slots in the rotor are slightly wider than the vanes received in the slots so that a fluid film forms between the rotor and the leading and trailing faces of each vane.

58. The pump of claim 57 further comprising a seal between a vane and the rotor to restrict fluid flow between them.

59. The pump of claim 58 wherein the seal is formed by contact between the vane and rotor.

60. A variable displacement vane pump, comprising:

a housing defining a chamber, a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the housing under pressure;

a containment ring or eccentric ring pivotally carried by the housing for movement between a first position and a second position and defining an opening with an internal surface;

a rotor carried by the housing for rotation relative to the internal surface and having a plurality of slots extending inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with each vane slidably received in a slot in the rotor;

a first actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a first direction, wherein the first actuator is responsive to a first actuation pressure signal;

a second actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a second direction, wherein the second actuator is responsive to a second actuation pressure signal;

an area defining a fluid chamber formed between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator; and

a control valve responsive to the differential between the first pressure signal and the second pressure signal to selectively apply, based on engine conditions, application of fluid under pressure to either the first or second actuator based on engine conditions.

61. The pump of claim 60 wherein the first actuator is a piston slidably carried by the housing.

62. The variable displacement vane pump of claim 60 wherein the second direction is in a direction opposite of the first direction.

63. The pump of claim 60 wherein the second actuator is a piston slidably carried by the housing.

64. The pump of claim 60 wherein the first actuator includes a spring that in yielding biases the containment ring or eccentric ring in the first direction.

65. The pump of claim 60 which also comprises another fluid chamber defined at least in part by the seal with fluid under pressure in the another fluid chamber defining the second actuator.

66. The pump of claim 60 which also comprises a control valve responsive to a first fluid pressure signal to control application of the fluid under pressure to the first actuator, and responsive to a second fluid pressure signal to control application of the fluid under pressure to the second actuator.

67. The pump of claim 60 which also comprises a pivot pin about which the containment ring or eccentric ring pivots, the pivot pin defining a pivot axis of the containment ring or eccentric ring which is offset from the axis of the rotor by about one-half the maximum eccentricity of the containment ring or eccentric ring relative to the rotor.

68. The pump of claim 60 which also comprises an inlet flow valve responsive to a fluid pressure signal above a threshold pressure to permit a portion of fluid discharged from the pump outlet to flow into the pump inlet during at least some fluid flow conditions.

69. The pump of claim 68 wherein the inlet flow valve is yieldably biased to a position preventing fluid discharged from the pump outlet to flow into the inlet of the pump and is displaced by a sufficiently high fluid pressure signal to a position permitting fluid discharged from the pump outlet to flow into the pump inlet.

70. The pump of claim 60 which also comprises a vane extension member carried by the housing and engageable with the vanes during at least certain positions of the rotor to ensure that at least two vanes extend outwardly from the exterior of the rotor at all times.

71. The pump of claim 70 wherein the vane extension member is a ring carried by the rotor to engage at least two vanes at all times.

72. The pump of claim 60 wherein the slots on the rotor extend radially inwardly of the rotor.

73. The pump of claim 60 wherein the seal is defined by direct contact between the containment ring or eccentric ring and the housing.

74. The pump of claim 60 wherein the seal is carried by the containment ring or eccentric ring.

75. The pump of claim 60 wherein the seal is carried on the housing.

76. The pump of claim 69 wherein fluid under pressure is communicated with the slots in the rotor to bias the vanes into contact with the cam surface.

77. The pump of claim 70 wherein the vane extension member further comprises a ring portion for engaging the two rings and oil pressure acting on the vanes for extending the vane outwardly.

78. The pump of claim 66 which also comprises an exhaust opening in the housing through which fluid in the fluid chamber is discharged under certain fluid flow conditions and wherein the control valve controls fluid flow from the fluid chamber through the exhaust opening in response to certain fluid pressures of the first and second pilot pressures.

79. The pump of claim 60 wherein the vanes have leading and trailing faces and the slots in the rotor are slightly wider than the vanes received in the slots so that a fluid film forms between the rotor and the leading and trailing faces of each vane.

80. The pump of claim 79 further comprising a seal between a vane and the rotor to restrict fluid flow between them.

81. The pump of claim 80 wherein the seal is formed by contact between the vane and rotor.

82. The pump of claim 69 wherein the inlet flow valve is biased by a spring.

83. The pump of claim 82 wherein the inlet flow valve is further biased by a pilot pressure signal.

84. A variable displacement pump system, comprising:

a pump assembly including a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the pump assembly under pressure;

a first actuator responsive to application of fluid under pressure and operable to cause displacement of the pump assembly towards a first displacement position;

a second actuator responsive to application of fluid under pressure and operable to cause displacement of the pump assembly towards a second displacement position;

wherein control and positioning of the first and second actuators are a function of a combination of a first pressure signal and a second pressure signal taken from discrete locations separated by a degree of inherent hydraulic resistance in a downstream fluid circuit;

an area defining a fluid chamber formed between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator; and

a control valve responsive to the differential between the first pressure signal and the second pressure signal to selectively apply, based on engine conditions, application of fluid under pressure to either the first or second actuator based on engine conditions.

85. The pump of claim 84 which also comprises an inlet flow valve responsive to a fluid pressure signal above a threshold pressure to permit a portion of fluid discharged from the pump outlet to flow into the pump inlet during at least some fluid flow conditions.

86. The pump of claim 85 wherein the inlet flow valve is yieldably biased to a position preventing fluid discharged from the pump outlet to flow into the inlet of the pump and is displaced by a sufficiently high fluid pressure signal to a position permitting fluid discharged from the pump outlet to flow into the pump inlet.

87. The pump of claim 84 which also comprises an exhaust opening in the housing through which fluid in the fluid chamber is discharged under certain fluid flow conditions and wherein the control valve controls fluid flow from the fluid chamber through the exhaust opening in response to certain fluid pressure signals of the first and second pilot pressure signals.

88. The pump of claim 86 wherein the inlet flow valve is biased by a spring.

89. The pump of claim 88 wherein the inlet flow valve is further biased by a pilot pressure signal.

90. A variable displacement pump system, comprising:

a pump assembly including a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the pump assembly under pressure;

a first actuator responsive to application of fluid under pressure and operable to cause displacement of the pump assembly towards a first displacement position; and

a second actuator responsive to application of fluid under pressure and operable to cause displacement of the pump assembly towards a second displacement position;

a flow control valve for mechanically varying the pump displacement;

a compression spring connectable at a first spring end to a spool of the flow control valve, wherein the compression spring maintains pressure on the flow control valve during regular operation, and provides return pressure in the absence of a pilot pressure on the flow control valve;

a target piston connected to the second end of the compression spring, wherein the target piston exerts a force on the compression spring;

wherein control and positioning of the first and second actuators are a function of a combination of a first pressure signal and a second pressure signal taken from discrete locations separated by a degree of inherent hydraulic resistance in a downstream fluid circuit acting on the target piston and the flow control valve for providing a variable pressure target for regulation of the pump'"'"'s displacement in response to varying engine speeds; and

an area defining a fluid chamber formed between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator;

wherein the flow control valve is responsive to the differential between the first pressure signal and the second pressure signal to selectively apply, based on engine conditions, application of fluid under pressure to either the first or second actuator based on engine conditions.

91. The pump of claim 90 wherein the target piston is positioned in a bore, the target piston being located on a first side by a pressure from a control input and on a second side by a grounded spring, the position in the bore acting as a reference for a regulation system to provide a predetermined regulation target pressure in the fluid circuit.

92. The pump of claim 91 wherein a multifunctional valve provides for varying the displacement of the pump by directing pressurized fluid to an on-stroke or de-stroke side of the pump assembly in response to the target piston acting on the multifunctional valve in a first direction, and a pressure input from the fluid circuit acting on the multifunctional valve in a second direction.

93. The pump of claim 92 wherein the multifunctional valve is a spool type valve having a biasing spring connected between the target piston and a spool valve, the target piston compressing the spring and biasing the spool valve for providing a target position in response to a control input from the pump assembly, the spool valve having passages for directing a control flow of fluid to the pump assembly, a control pressure from the fluid circuit acting on the spool valve against the biasing spring for seeking a predetermined target pressure.

94. A variable displacement vane pump, comprising:

a housing defining a chamber, a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the housing under pressure;

a containment ring or eccentric ring pivotally carried by the housing for movement between a first position and a second position and defining an opening with an internal surface;

a rotor carried by the housing for rotation relative to the internal surface and having a plurality of slots extending inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with each vane slidably received in a slot in the rotor;

a first actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a first direction;

a second actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a second direction;

wherein control and positioning of the first and second actuators are a function of a combination of a first pressure signal and a second pressure signal taken from discrete locations separated by a degree of inherent hydraulic resistance in a downstream fluid circuit; and

a vane extension member carried by the housing and engageable with the vanes during at least certain positions of the rotor to ensure that at least two vanes extend outwardly from the exterior of the rotor at all times.

95. The pump of claim 94 wherein the first actuator is a piston slidably carried by the housing.

96. The variable displacement vane pump of claim 94 wherein the second direction is in a direction opposite of the first direction.

97. The pump of claim 94 wherein the second actuator is a piston slidably carried by the housing.

98. The pump of claim 94 wherein the first actuator includes a spring that in yielding biases the containment ring or eccentric ring in the first direction.

99. The pump of claim 94 which also comprises a seal between the containment ring or eccentric ring and the housing defining a fluid chamber between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator.

100. The pump of claim 99 which also comprises another fluid chamber defined at least in part by the seal with fluid under pressure in the another fluid chamber defining the second actuator.

101. The pump of claim 94 which also comprises a control valve responsive to a first fluid pressure signal to control application of the fluid under pressure to the first actuator, and responsive to a second fluid pressure signal to control application of the fluid under pressure to the second actuator.

102. The pump of claim 94 which also comprises a pivot pin about which the containment ring or eccentric ring pivots, the pivot pin defining a pivot axis of the containment ring or eccentric ring which is offset from the axis of the rotor by about one-half the maximum eccentricity of the containment ring or eccentric ring relative to the rotor.

103. The pump of claim 94 which also comprises an inlet flow valve responsive to a fluid pressure signal above a threshold pressure to permit a portion of fluid discharged from the pump outlet to flow into the pump inlet during at least some fluid flow conditions.

104. The pump of claim 103 wherein the inlet flow valve is yieldably biased to a position preventing fluid discharged from the pump outlet to flow into the inlet of the pump and is displaced by a sufficiently high fluid pressure signal to a position permitting fluid discharged from the pump outlet to flow into the pump inlet.

105. The pump of claim 94 wherein the vane extension member is a ring carried by the rotor to engage at least two vanes at all times.

106. The pump of claim 94 wherein the slots on the rotor extend radially inwardly of the rotor.

107. The pump of claim 99 wherein the seal is defined by direct contact between the containment ring or eccentric ring and the housing.

108. The pump of claim 99 wherein the seal is carried by the containment ring or eccentric ring.

109. The pump of claim 99 wherein the seal is carried on the housing.

110. The pump of claim 104 wherein fluid under pressure is communicated with the slots in the rotor to bias the vanes into contact with the cam surface.

111. The pump of claim 94 wherein the vane extension member further comprises a ring portion for engaging the two rings and oil pressure acting on the vanes for extending the vane outwardly.

112. The pump of claim 101 which also comprises an exhaust opening in the housing through which fluid in the fluid chamber is discharged under certain fluid flow conditions and wherein the control valve controls fluid flow from the fluid chamber through the exhaust opening in response to certain fluid pressures of the first and second pilot pressures.

113. The pump of claim 94 wherein the vanes have leading and trailing faces and the slots in the rotor are slightly wider than the vanes received in the slots so that a fluid film forms between the rotor and the leading and trailing faces of each vane.

114. The pump of claim 113 further comprising a seal between a vane and the rotor to restrict fluid flow between them.

115. The pump of claim 114 wherein the seal is formed by contact between the vane and rotor.

116. The pump of claim 104 wherein the inlet flow valve is biased by a spring.

117. The pump of claim 116 wherein the inlet flow valve is further biased by a pilot pressure signal.

118. A variable displacement vane pump, comprising:

a housing defining a chamber, a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the housing under pressure;

a containment ring or eccentric ring pivotally carried by the housing for movement between a first position and a second position and defining an opening with an internal surface;

a rotor carried by the housing for rotation relative to the internal surface and having a plurality of slots extending inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with each vane slidably received in a slot in the rotor;

a first actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a first direction;

a second actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a second direction;

a seal between the containment ring or eccentric ring and the housing defining a fluid chamber between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator; and

another fluid chamber defined at least in part by the seal with fluid under pressure in the another fluid chamber defining the second actuator.

119. The pump of claim 118 which also comprises an inlet flow valve responsive to a fluid pressure signal above a threshold pressure to permit a portion of fluid discharged from the pump outlet to flow into the pump inlet during at least some fluid flow conditions.

120. The pump of claim 119 wherein the inlet flow valve is yieldably biased to a position preventing fluid discharged from the pump outlet to flow into the inlet of the pump and is displaced by a sufficiently high fluid pressure signal to a position permitting fluid discharged from the pump outlet to flow into the pump inlet.

121. The pump of claim 118 which also comprises a vane extension member carried by the housing and engageable with the vanes during at least certain positions of the rotor to ensure that at least two vanes extend outwardly from the exterior of the rotor at all times.

122. The pump of claim 121 wherein the vane extension member is a ring carried by the rotor to engage at least two vanes at all times.

123. The pump of claim 118 wherein the seal is carried by the containment ring or eccentric ring.

124. The pump of claim 120 wherein fluid under pressure is communicated with the slots in the rotor to bias the vanes into contact with the cam surface.

125. The pump of claim 124 wherein the vane extension member further comprises a ring portion for engaging the two rings and oil pressure acting on the vanes for extending the vane outwardly.

126. The pump of claim 120 wherein the inlet flow valve is biased by a spring.

127. The pump of claim 126 wherein the inlet flow valve is further biased by a pilot pressure signal.

128. A variable displacement vane pump, comprising:

a housing defining a chamber, a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the housing under pressure;

a containment ring or eccentric ring pivotally carried by the housing for movement between a first position and a second position and defining an opening with an internal surface;

a rotor carried by the housing for rotation relative to the internal surface and having a plurality of slots extending inwardly into the rotor from an exterior of the rotor;

a plurality of vanes carried by the rotor with each vane slidably received in a slot in the rotor;

a first actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a first direction, wherein the first actuator is responsive to a first actuation pressure signal;

a second actuator responsive to application of fluid under pressure and operable to pivot the containment ring or eccentric ring in a second direction, wherein the second actuator is responsive to a second actuation pressure signal; and

an inlet flow valve responsive to a fluid pressure signal above a threshold pressure to permit a portion of fluid discharged from the pump outlet to flow into the pump inlet during at least some fluid flow conditions.

129. The pump of claim 128 wherein the first actuator is a piston slidably carried by the housing.

130. The variable displacement vane pump of claim 128 wherein the second direction is in a direction opposite of the first direction.

131. The pump of claim 128 wherein the second actuator is a piston slidably carried by the housing.

132. The pump of claim 128 wherein the first actuator includes a spring that in yielding biases the containment ring or eccentric ring in the first direction.

133. The pump of claim 128 which also comprises a seal between the containment ring or eccentric ring and the housing defining a fluid chamber between the housing and containment ring or eccentric ring with fluid under pressure in the fluid chamber defining the first actuator.

134. The pump of claim 133 which also comprises another fluid chamber defined at least in part by the seal with fluid under pressure in the another fluid chamber defining the second actuator.

135. The pump of claim 128 which also comprises a control valve responsive to a first fluid pressure signal to control application of the fluid under pressure to the first actuator, and responsive to a second fluid pressure signal to control application of the fluid under pressure to the second actuator.

136. The pump of claim 128 which also comprises a pivot pin about which the containment ring or eccentric ring pivots, the pivot pin defining a pivot axis of the containment ring or eccentric ring which is offset from the axis of the rotor by about one-half the maximum eccentricity of the containment ring or eccentric ring relative to the rotor.

137. The pump of claim 128 wherein the inlet flow valve is yieldably biased to a position preventing fluid discharged from the pump outlet to flow into the inlet of the pump and is displaced by a sufficiently high fluid pressure signal to a position permitting fluid discharged from the pump outlet to flow into the pump inlet.

138. The pump of claim 128 which also comprises a vane extension member carried by the housing and engageable with the vanes during at least certain positions of the rotor to ensure that at least two vanes extend outwardly from the exterior of the rotor at all times.

139. The pump of claim 138 wherein the vane extension member is a ring carried by the rotor to engage at least two vanes at all times.

140. The pump of claim 128 wherein the slots on the rotor extend radially inwardly of the rotor.

141. The pump of claim 133 wherein the seal is defined by direct contact between the containment ring or eccentric ring and the housing.

142. The pump of claim 133 wherein the seal is carried by the containment ring or eccentric ring.

143. The pump of claim 133 wherein the seal is carried on the housing.

144. The pump of claim 137 wherein fluid under pressure is communicated with the slots in the rotor to bias the vanes into contact with the cam surface.

145. The pump of claim 138 wherein the vane extension member further comprises a ring portion for engaging the two rings and oil pressure acting on the vanes for extending the vane outwardly.

146. The pump of claim 135 which also comprises an exhaust opening in the housing through which fluid in the fluid chamber is discharged under certain fluid flow conditions and wherein the control valve controls fluid flow from the fluid chamber through the exhaust opening in response to certain fluid pressures of the first and second pilot pressures.

147. The pump of claim 128 wherein the vanes have leading and trailing faces and the slots in the rotor are slightly wider than the vanes received in the slots so that a fluid film forms between the rotor and the leading and trailing faces of each vane.

148. The pump of claim 147 further comprising a seal between a vane and the rotor to restrict fluid flow between them.

149. The pump of claim 148 wherein the seal is formed by contact between the vane and rotor.

150. The pump of claim 137 wherein the inlet flow valve is biased by a spring.

151. The pump of claim 150 wherein the inlet flow valve is further biased by a pilot pressure signal.

152. A variable displacement pump system, comprising:

a pump assembly including a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the pump assembly under pressure;

a first actuator responsive to application of fluid under pressure and operable to cause displacement of the pump assembly towards a first displacement position;

a second actuator responsive to application of fluid under pressure and operable to cause displacement of the pump assembly towards a second displacement position;

wherein control and positioning of the first and second actuators are a function of a combination of a first pressure signal and a second pressure signal taken from discrete locations separated by a degree of inherent hydraulic resistance in a downstream fluid circuit; and

an inlet flow valve responsive to a fluid pressure signal above a threshold pressure to permit a portion of fluid discharged from the pump outlet to flow into the pump inlet during at least some fluid flow conditions.

153. The pump of claim 152 which also comprises a control valve responsive to a first and a second pressure signal to control application of fluid pressure to the first and second actuators.

154. The pump of claim 152 wherein the inlet flow valve is yieldably biased to a position preventing fluid discharged from the pump outlet to flow into the inlet of the pump and is displaced by a sufficiently high fluid pressure signal to a position permitting fluid discharged from the pump outlet to flow into the pump inlet.

155. The pump of claim 152 which also comprises an exhaust opening in the housing through which fluid in the fluid chamber is discharged under certain fluid flow conditions and wherein the control valve controls fluid flow from the fluid chamber through the exhaust opening in response to certain fluid pressures of the first and second pilot pressures.

156. The pump of claim 154 wherein the inlet flow valve is biased by a spring.

157. The pump of claim 156 wherein the inlet flow valve is further biased by a pilot pressure signal.

158. A variable displacement pump system, comprising:

a pump assembly including a pump inlet through which fluid enters the housing and a pump outlet through which fluid is discharged from the pump assembly under pressure;

a first actuator responsive to application of fluid under pressure and operable to cause displacement of the pump assembly towards a first displacement position; and

a second actuator responsive to application of fluid under pressure and operable to cause displacement of the pump assembly towards a second displacement position;

a flow control valve for mechanically varying the pump displacement;

a compression spring connectable at a first spring end to a spool of the flow control valve, wherein the compression spring maintains pressure on the flow control valve during regular operation, and provides return pressure in the absence of a pilot pressure on the flow control valve; and

a target piston connected to the second end of the compression spring, wherein the target piston exerts a force on the compression spring;

wherein control and positioning of the first and second actuators are a function of a combination of a first pressure signal and a second pressure signal taken from discrete locations separated by a degree of inherent hydraulic resistance in a downstream fluid circuit acting on the target piston and the flow control valve for providing a variable pressure target for regulation of the pump'"'"'s displacement in response to varying engine speeds;

wherein the target piston is positioned in a bore, the target piston being located on a first side by a pressure from a control input and on a second side by a grounded spring, the position in the bore acting as a reference for a regulation system to provide a predetermined regulation target pressure in the fluid circuit.

159. The pump of claim 158 wherein a multifunctional valve provides for varying the displacement of the pump by directing pressurized fluid to an on-stroke or de-stroke side of the pump assembly in response to the target piston acting on the multifunctional valve in a first direction, and a pressure input from the fluid circuit acting on the multifunctional valve in a second direction.

160. The pump of claim 159 wherein the multifunctional valve is a spool type valve having a biasing spring connected between the target piston and a spool valve, the target piston compressing the spring and biasing the spool valve for providing a target position in response to a control input from the pump assembly, the spool valve having passages for directing a control flow of fluid to the pump assembly, a control pressure from the fluid circuit acting on the spool valve against the biasing spring for seeking a predetermined target pressure.