Variable displacement variable pressure vane pump system

1. A variable displacement variable pressure vane pump system for providing lubrication oil to a mechanical system comprises:

a variable displacement variable pressure vane pump having a control slider which is moveable to alter the displacement of the pump;

a biasing means to bias the control slider towards a position corresponding to the maximum displacement position of the pump;

a first control mechanism responsive to the pressure of the lubrication oil output from the pump to apply a force to the control slider to counter a biasing force of the biasing means and to urge the control slider away from the position corresponding to the maximum displacement position of the pump;

a second control mechanism responsive to the pressure of the lubrication oil output from the pump to apply a force to the control slider to alter the displacement of the pump;

a control means operable to vary the lubrication oil supplied to the second control mechanism to alter the output of the pump to closely correspond to the lubrication requirements of the mechanical system; and

a third control mechanism responsive to the pressure of the lubrication oil output from the pump to apply a force to the control slider to counter the biasing force of the biasing means and to urge the control slider away from the position corresponding to the maximum displacement position of the pump and wherein the control means is operable to vary lubrication oil output from either or both of the second control mechanism and the third control mechanism to alter the output of the pump to closely correspond to the lubrication requirements of the mechanical system.

2. The variable displacement variable pressure pump system of claim 1 wherein the first control mechanism comprises a control chamber formed between the exterior of the control slider, a control slider seal, a control slider pivot point and the interior surface of a housing of the pump, the pressurized lubricating oil provided to the control chamber directly producing the force on the control slider.

3. The variable displacement variable pressure pump system of claim 2 wherein the control means comprises a solenoid valve.

4. The variable displacement variable pressure pump system of claim 3 wherein the solenoid valve is electrically controlled by an engine control unit.

5. The variable displacement variable pressure pump system of claim 3 wherein the solenoid valve is operable to alter the pressure of the pressurized lubrication oil provided to the second control mechanism.

6. The variable displacement variable pressure pump system of claim 1 wherein the first and second control mechanisms each comprise chambers being isolated from each other when the control means ceases the supply of lubrication oil to the second control mechanism.

7. The variable displacement variable pressure pump system of claim 1 wherein the mechanical system is an internal combustion engine.

8. The variable displacement variable pressure pump system of claim 1 wherein the mechanical system is an automatic transmission.

9. The variable displacement variable pressure pump system of claim 1 wherein the pressurized lubrication oil is supplied to the first and second control mechanisms from an outlet of the pump.

10. The variable displacement variable pressure pump system of claim 1 wherein the pressurized lubrication oil is supplied to the first and second control means from a lubrication oil gallery of the mechanical system.

11. A variable displacement variable pressure vane pump system for providing lubrication oil to a mechanical system comprises:

a variable displacement variable pressure vane pump having a control slider which is moveable to alter the displacement of the pump;

a biasing means to bias the control slider towards a position corresponding to the maximum displacement position of the pump;

a first control mechanism responsive to the pressure of the lubrication oil output from the pump to apply a force to the control slider to counter a biasing force of the biasing means and to urge the control slider away from the position corresponding to the maximum displacement position of the pump;

a second control mechanism responsive to the pressure of the lubrication oil output from the pump to apply a force to the control slider to alter the displacement of the pump; and

a control means operable to vary the lubrication oil supplied to the second control mechanism to alter the output of the pump to closely correspond to the lubrication requirements of the mechanical system, further comprising a third control mechanism responsive to the pressure of the lubrication oil output from the pump to apply a force to the control slider to counter the biasing force of the biasing means and to urge the control slider away from the position corresponding to the maximum displacement position of the pump and wherein the control means is further operable to vary the supply of lubrication oil between the second control mechanism and the third control mechanism to alter the output of the pump to closely correspond to the lubrication requirements of the mechanical system and wherein the second control mechanism and the third control mechanism create different magnitudes of force for a given pressure of lubrication oil.

12. The variable displacement variable pressure pump system of claim 11 , wherein the first control mechanism comprises a control chamber formed between the exterior of the control slider, a control slider seal, a control slider pivot point and the interior surface of a housing of the pump, the pressurized lubricating oil provided to the control chamber directly producing the force on the control slider.

13. The variable displacement variable pressure pump system of claim 12 , wherein the pressurized lubrication oil is supplied to the first and second control mechanisms from an outlet of the pump.

14. The variable displacement variable pressure pump of claim 13 , wherein the second and third control mechanisms include pistons rigidly connected to one another.