OUT ROTOR DRIVE ELECTRICAL VANE PUMP

Abstract

A variable displacement vane oil pump for use in a vehicle powertrain includes a mechanical drive coupled to a first portion of a rotor and an electrical drive coupled to a second portion of the rotor such that the variable displacement vane pump may be driven by either or both the mechanical and electrical drives to achieve greater efficiency and control while maintaining oil pressure under all circumstances including start/stop conditions. The oil pump, when being driven by the mechanical drive only, remains coupled to the electric drive such that it rotates the motor of the electric drive to generate electricity that may be used to recharge a source of electricity such as a battery. The electric drive further includes a four phase controller for controlling the motor of the electric drive to efficiently operate the variable displacement vane oil pump without the use of a pressure relief valve.

Description

FIELD OF THE DISCLOSURE

The present disclosure generally relates to fluid pumps, and more particularly, to a variable displacement pump for use in a transmission in a vehicle such as an automobile, truck, van, utility, fleet, cargo or the like.

BACKGROUND

Mechanical systems, such as internal combustion engines, transmissions and other types of powertrains typically include a lubrication pump to provide lubricating oil, under pressure, to many of the moving components and/or subsystems of the mechanical systems. In most cases, the lubrication pump is driven by a mechanical linkage to the mechanical system and thus the operating speed and output of the pump varies with the operating speed of the mechanical system. While the lubrication requirements of the mechanical system also vary with the operating speed of the mechanical system, unfortunately the relationship between the variation in the output of the pump and the variation of the lubrication requirements of the mechanical system is generally nonlinear. Internal oil pumps are typically continuously driven. While known arrangements are fairly simple to construct, continuously mechanically driving the pump may not be the most efficient way of operating the vehicle let alone even possible in some electric vehicle applications.

It is generally known to have a variable displacement vane pump for use in a transmission in a vehicle including a variable displacement vane pump. One particular example is disclosed in U.S. Pat. No. 4,342,545, to Schuster, the entire contents of which are incorporated herein. Variable displacement pumps are generally known in transmission control systems, however, these prior art devices have generally been of the gerotor or sliding ring type in which the control thereof is maintained by a spring. It is also generally known in electric vehicle applications to provide two pumps—a mechanical pump driven by a power take off from the engine and an electric motor driven pump for use when the engine is not running. This adds significant expense and complexity as well additional potential failure modes and control issues. There is also known an externally mounted electric fluid pump for pumping fluid within a power transmission device as disclosed in US Patent Application Publication Number 2010/0290934A1, the entire contents of which are incorporated herein.

Despite the long known solutions, there remains a significant need to provide an improved vane pump capable of providing improved performance and gains in efficiency and packaging of the pump.

Despite the long known solutions, there remains a significant need to provide an improved pump that can overcome the problems of the known art.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a pump for a motor vehicle. In its broad aspects the pump includes both electrical and mechanical drives which may be independently controlled to actuate the pumping mechanism. The pump in general includes a vane pump with a mechanical drive coupled to a first portion of a rotor and an electrical drive coupled to a second portion of the rotor such that the variable displacement vane pump may be driven by either or both the mechanical and electrical drives to achieve greater efficiency and control while maintaining oil pressure under all circumstances including start/stop conditions. In one embodiment, the oil pump, when being driven by the mechanical drive only, remains coupled to the electric drive such that it rotates the motor of the electric drive to generate electricity that may be used to recharge a source of electricity such as a battery. In a preferred embodiment, the electric drive further includes a four phase controller for controlling the motor of the electric drive to efficiently operate the variable displacement vane oil pump without the use of a pressure relief valve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front top perspective view of a representative embodiment of a pump in accordance with the present invention;

FIG. 1A is a front bottom perspective view of a representative embodiment of a pump in accordance with the present invention;

FIG. 2 is a rear bottom perspective view of a representative embodiment of a pump in accordance with the present invention;

FIG. 2A is a rear bottom perspective view of a representative embodiment of a pump in accordance with the present invention;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1 of a representative embodiment of a pump in accordance with the present invention;

FIG. 4 is a detailed sectional view of the pump portion of a representative embodiment of a pump in accordance with the present invention;

FIG. 5 is a detailed sectional view of the inner rotor of a representative embodiment of a pump in accordance with the present invention;

FIG. 6 is a sectional view of the static parts in the pump portion of a representative embodiment of a pump in accordance with the present invention;

FIG. 7 is a sectional view in perspective of the outer rotor of a representative embodiment of a pump in accordance with the present invention;

FIG. 8 is a sectional view of the pump portion taken along line 8-8 of FIG. 1 of a representative embodiment of a pump in accordance with the present invention;

FIG. 9 is a detailed sectional view taken from FIG. 8 of a representative embodiment of a pump in accordance with the present invention;

FIG. 10 is a perspective view showing the internal pump components of a representative embodiment of a pump in accordance with the present invention;

FIG. 11 is a front perspective view of the internal pump components of FIG. 10 of a representative embodiment of a pump in accordance with the present invention; and

FIG. 12 is an illustrative view showing the pump control process of the present invention.

DETAILED DESCRIPTION

Referring generally to the Figures, there is shown an exemplary embodiment of a variable displacement vane pump 10 including a mechanical drive 12 and an electrical drive 14. Referring in particular to FIGS. 1, 2 and 3, the pump 16 is shown including a housing 18 has an inlet 20 and an outlet 22. The pump 16 includes a central shaft 24 for mechanically driving the pump 16. The shaft 24 may be coupled to a power takeoff from an engine (not shown) as is commonly done with oil pumps. The housing 18 of the pump 16 includes an extension portion 26 for coupling the electrical drive 14 to the pump 16. The extension portion 26 has a generally round shape for alignment and coupling to a correspondingly shaped member 28 on the electrical drive 14. The electrical drive 14 is shown as a motor 30 including an output in the form of a rotating motor shaft 32 including a drive member such as gear member 34 coupled thereto and located and aligned in the extension portion 26 of the housing 18 to couple with a engagement member such as gear 36 of outer rotor 38 of the pump 16 as further described below. While the electrical drive 14 is coupled to the outer rotor 38 using a pair of gears each having gear teeth, it should be understood that any known or appropriate engagement or drive members are to be used for coupling the electrical drive 14 to the outer rotor 38 for transferring work from the electrical drive 14 to the outer rotor 38 and vice versa and for doing so in both rotating directions.

FIGS. 1A and 2A drawings of the exemplary embodiment of FIGS. 1 and 2 shown from an alternate perspective to provide further understanding of the present disclosure and invention. The configuration of the variable displacement pump of FIGS. 1 and 2 is chosen, at least in part, based upon packaging considerations, it should be understood that alternative arrangements and alignments of the inlet and outlet, the motor 30 of the electrical drive 14 may be accomplished once the details of the present disclosure and teachings are understood.

Referring generally to the exemplary embodiments, the pump 16 of the present disclosure works on a unique principle that there are two rotors—an inner rotor 40 and an outer rotor 38. The inner rotor 40 is controlled and driven by the mechanical drive and the outer rotor 38 is controlled and driven by the electrical drive 14. Because the motor 30 of the electrical drive 14 regulates the speed of the outer rotor 38 of the binary pump 16, the differential speed between the inner rotor 40 and the out rotor 38 controls the real speed of the pump 16. Further, because the mechanical and electrical drive 14 are separate and independently controlled, the pump 16 of the present disclosure is capable of operating in numerous states and conditions not previously achieved in an oil pump 16 for use in a powertrain of a vehicle. Since the mechanical drive 12 may be, in one exemplary embodiment, coupled to a power takeoff from the operating internal combustion engine, the speed of the inner rotor 40 is directly related to the speed of the engine. As the engine speed increases, the mechanical drive 12 speed increases and the inner rotor of the pump rotates faster. Since the electrical drive 14 and its motor 30 are independently controlled, it is possible for the electrical drive 14 to rotate the outer rotor 38 of the pump 16 at any desired speed and in any desired direction based upon the controller of the motor 30. It is also possible to the keep the outer rotor 38 of the pump 16 static by not supplying any power to the motor 30 of the electrical drive 14. When the mechanical drive 12 is not rotating, such as when the internal combustion stops working when the vehicle is stopped at a red light and the engine is shut off to stop using fuel and to eliminate emissions, the electrical drive 14 and its motor 30 can be run using power from the vehicle's batter to rotate the outer rotor 38 at a speed to maintain a sufficient flow of fluid through the pump 16 to maintain a sufficient or desired pressure of fluid within the gallery of the internal combustion engine. Such an embodiment allows for oil pressure to be maintained while the vehicle is stopped and the engine is not operating in order to maintain the position and/or condition of other systems in the engine, such as a hydraulic cam phase position device located using an ephaser porting technique. Additionally, as should be readily understood, the pump 16 of the exemplary embodiment of the present disclosure has two operating inputs, the mechanical drive 12 and the electrical drive 14. Thus, if one of the drives fails for any reason, the pump 16 can still maintain pressure on the fluid using the non-failed drive. This is particularly advantageous as compared to an engine having a pump having only an electrical drive which is dependent upon a supply of sufficient electricity to operate the motor which may not always be available such as where a battery has been run down or become inoperable for some reason.

Referring still to the description of the exemplary embodiments of the disclosure, the housing 18 is preferably made of a metal material and has a first portion 42 and a second portion 44 as generally shown in FIGS. 3, 4 and 6. The first portion 42 of the housing 18 corresponds with the inlet side of the pump 16 and the second portion 44 of the housing 18 corresponds with the outlet side but such relationship may be reversed. The first 42 and second 44 portions of the housing 18 include an inlet collector 46 and an outlet collector 48, respectively, as best shown in FIG. 6 for directing the fluid being pumped (such as oil) through the housing 18 from the inlet 20 to the outlet 22 by the operation of the inner and outer rotors of the vane pump 10.

A generally disc-shaped, axial stop is located between the first 42 and second 44 portions of the housing 18 as shown in FIGS. 6, and 9. The first 42 and second 44 portions of the housing 18 are preferably coupled together using any known or appropriate fastener or other coupling device appropriate for securing the first 42 and second 44 portions of the housing 18 during operation. The pump device 16 further includes a static ring seal member 50 located in the pump interior proximal the axial stop 52 and between the second housing portion 44 and the outer rotor member 38 as shown in FIGS. 6, 8 and 9. As shown in FIGS. 4 and 6, an anti-rotation ring 54 is provided in the second portion 44 of the housing 18 between the static seal ring 50 and the second housing portion 44 to prevent rotation of the static seal ring 50 due to the forces of the outer rotor 38 located in proximity to the static ring seal member 50 as shown in FIGS. 4, 8 and 9.

Referring in particular to FIG. 6, the housing 18 further includes a central chamber 56 having a generally cylindrical shape for receiving the inner 40 and outer 38 rotors of the binary pump 16. The housing 18 further includes a first central passage portion 58 located in the first housing portion 42 and a second central passage portion 60 located in the second housing, the first 58 and second 60 central passage portions defining a central passage for receiving the shaft 24 of the pump and for supporting rotation of the inner 40 and outer 38 rotors within the chamber 56 of the housing 18. As shown in FIGS. 3-5, the shaft 24 is coupled to the housing a fastener 64 and disc member 66. The shaft 24 is rotatably supported in the central passage of the housing any known or appropriate bearings which will function to allow the inner rotor to efficiently rotate therein. The shaft 24 includes splines 68 located thereon for alignment with and fixedly coupling the shaft 24 to matching splines 68 on a central passage 70 of the inner rotor of the pump as best shown in FIG. 4. Any known or appropriate spline, mechanical lock, formed or altered structure or other device, such as a fastener or similar device, may be used to couple the inner rotor to the shaft.

The inner rotor assembly 72, referring in particular to FIGS. 4 and 5, includes an inner rotor member 74 that is in one exemplary embodiment a formed structure, such as a cast aluminum or any other known or appropriate material, and has a generally cylindrical overall shape and a plurality of radiating structures forming a plurality of radiating pockets or passages 76 for receiving the pumping fins 78 of the pump as is generally well known and understood in the vane pump 12 and variable displacement pump devices. Further, the pumping fins 78 are biased radiated outward using any know or appropriate biasing device such as a spring 80 of any type or other known or appropriate structure that will function appropriately to allow the pumping fins to reciprocate in the passages 76 of the inner rotor member 74.

Referring in particular to FIG. 7, the outer rotor 38 assembly is shown in partial cross-section. The outer rotor 38 assembly includes a first or inlet disc member 82 including a gear 36 located on an outer periphery. The inlet disc 82 has a central passage 86 for having the shaft 92 pass there through and an axially extending, generally elliptically shaped boss 88 about the central passage 86. The inlet disc 82 is preferably formed from a relatively light weight material appropriate for the application such as aluminum or magnesium material. The inlet disc 82 includes an inlet port 90 for receiving fluid from the inlet collector of the housing. The outer rotor 38 further includes a second or outlet disc member 92 also having a central passage 94 and an axially extending, generally elliptically shaped boss about the central passage similar to that of the inlet disc 82. Notably, the second or outlet disc member 92 does not include a gear or gear teeth located on a periphery of the disc member 82. The outlet disc member 92 also includes an outlet port 98 for receiving fluid from the inner rotor 40 and conveying the fluid to the outlet collector 48 of the housing and then to the outlet 22 of the housing 18. Generally, the outlet disc member 92 is made similarly to the inlet disc member 82.

The outer rotor 38 further includes a middle member 100 having a generally cylindrical shape and defining the inner passage 102 of the outer rotor 38. The inlet disc member 82, outlet disc member 92 and middle member 100 are preferably coupled together using a pair of fasteners 84 as best shown in FIG. 7. Alternatively, the inlet disc member 82, outlet disc member 92 and middle member 100 may be coupled together using any known or appropriate coupling technique or mechanism. As best shown in FIGS. 8 and 9, the inner 40 and outer 38 rotors are supported in the central passage 94 of the housing journal bearings and appropriate lubrication pathways 104. In operation, the inner 40 and outer 38 rotors develop a hydraulic, axial thrust as noted by the arrows 106 shown in FIGS. 3 and 9 due to the flow of the fluid in the outlet collector 48 of the housing 18. Further, a minimized clearance is created between the outlet disc member 92 of the outlet rotor assembly 38 and the static ring seal 50 of the housing 18. As shown in FIGS. 8, 10 and 11, the relative rotation of the inner 40 and outer 38 rotors causes the movement of the vanes within the inner passage 102 of the outer rotor 38 creates the pumping action of the variable displacement pump causing fluid to flow from the inlet 20 of through the inner 40 and outer 38 rotors and out the outlet 22 of the pump 16. Since the relative movement of the inner 40 and outer 38 rotors may be selectively controlled by the electrical drive 14, the variable displacement pump 16 of the present disclosure is highly controllable and usable in a variety of applications not previously possible.

The control of the electrical drive 14 of the pump is preferably done using a quadrant electrical motor driver capable of controlling not only the speed and direction of motor rotation, but also the direction of motor torque. One example of such a four quadrant motor control device is the fully programmable Millipak 4 Quadrant Regenerative Braking Motor Controller by Sevcon, which is a 24 to 48 volt, direct current controller including an armature current rating of 130 amps continuous and having 325 amps for up to one minute with regenerative braking and contactor-free reversing, designed for use with Etek, LEMCO, Scott, and other permanent magnet motors. Such a four-quadrant electrical motor driver allows for the regenerative use of the pump from the mechanical input to convert the mechanical energy of the motor and the connected load into electrical energy which may returned (or regenerated) to a direct current power source such as a capacitor or a battery of the vehicle. A definitional chart of the four quadrants of motor control is provided in FIG. 12.

Referring now to FIG. 12 when the electrical drive 14 is operating in quadrants I and Ill, both motor rotation 110 and torque 112 are in the same direction and the electrical drive 14 and the pump 16 function as a conventional non-regenerative unit. The unique characteristics of the electrical drive 14 become apparent in reference to quadrants II and IV. In quadrants II and IV, the motor torque 112 opposes the direction of motor rotation 110 during operation of the electrical drive 14 and the pump 16 which allows the electrical drive to provide a controlled braking or retarding force to the pump 16 during operation. A high performance regenerative drive is able to switch rapidly between driving (or acceleration) mode (quadrants I and III) and braking (or deceleration) mode (quadrants II and IV) while simultaneously controlling the direction of motor rotation.

Considering the above operation of the motor 30 of the electrical drive 14, it should be noted that there is clockwise (CW) and counter counter-clockwise (CCW) rotations of the motor (and thus the outer rotor of the pump) and there is acceleration and deceleration torques. Accordingly, there are four distinct areas, or quadrants, of operation or control of the motor of the electrical drive of the pump.

Quadrants I and III represent the motor 30 applying torque 112 in the direction of rotation of the pump, while quadrants II and IV represent applying torque 112 opposite the direction of the motion. In quadrants I and III the flow of energy is from electrical to mechanical. The motor 30 is converting electrical power from the drive 14 into motion in the system. In quadrants II and IV, the motor 30 is actually acting as a generator. The motion of the system is being converted into electrical power. When torque 112 is reversed, energy stored in the rotating load of the inner rotor 40 may be transferred back to the power supply, quickly charging an energy storage device such as a storage capacitor or other battery. In view of the above, it should be understood that it becomes desirable to provide a protection device in the event a significant amount of energy is returned to the energy storage device. In one exemplary embodiment, it is contemplated to provide a clamp circuit to dissipate energy being returned to the energy storage device and to limit the maximum voltage. Additionally, it is contemplated that an over-voltage comparator may be employed to disable the output if the bus voltage exceeds the clamp voltage by more than a few volts. Four quadrant control and operation of the motor 30 of the electrical drive 14 means that the motor can operate in all four quadrants of speed vs. torque. It should be understood that many control strategies may be used in operating the pump. In one exemplary embodiment, a six step control strategy is used where positions are obtained from hall sensors and pairs of transistors are switched in the motor 30. In this embodiment, the voltage has trapezoidal form and the current shape includes six steps in a pulse width module (PWM) controller. The duty cycle of the PWM control may be changed to alter the current in the motor 30. Accordingly, position and current sensor information may be used to do the commutation. A look-up table may be used for commutation and PWM duty cycle for altering the current. Alternatively, it is contemplated that a sinusoidal current shape may be used for control to obtain improved harmonics during operation of the electrical drive 14.

In the case of sinusoidal control, it is contemplated that the angle of the motor may be obtained from the position sensors to generate a clean 3 phase reference which may be compared to the actual 3 phase currents which may then be processed through a PID and then through a state machine to switch the FETs of the motor. The signal may be divided into four sections: 0 to 0.5, 0.5 to 1, 0 to −0.5, and −0.5 to 1 and used to commutate the switches of the motor.

The above description and details make clear that the unique variable displacement pump 16 of the exemplary disclosure including a mechanical drive 12 and an electrical drive 14 allows for the regulating of the pump output 22 using a relatively smaller mechanical pump than compared to a mechanical drive only device while providing greater control and performance and satisfying additional objectives. The variable displacement pump 16 of the present exemplary disclosure has particular advantages in application as an oil pump in a vehicle having frequent start/stop and go operations. Further, since the variable displacement pump of the exemplary disclosure includes both mechanical and electrical drives, a relatively high ratio gear may be used providing for improved cold start performance. In one exemplary embodiment, the gear ratio is preferably selected to be between about 10:1 and about 20:1 and more generally is selected to be between about 5:1 and about 40:1. The gear ratio is preferably selected for the motor of the electrical drive to operate at a relatively high efficiency. The gear ratio is preferably optimized for a particular application and output objectives.

The variable displacement pump 16 of the exemplary embodiments of the present disclosure has both a mechanical drive 12 and an electrical drive 14 and the motor 30 of the electrical drive 14 may include a four quadrant control strategy and to convert mechanical energy from the mechanical drive 12 to generate electrical energy in the motor 30 of the electrical drive 14. The variable displacement pump 16 of the exemplary disclosure having both mechanical 12 and electrical 14 drives is more robust since it may still be operated if either one of the mechanical 12 or electrical 14 drives fails. Similarly, the single variable displacement pump 16 of the exemplary disclosure having both mechanical 12 and electrical 14 drives allows for an engine to be shut off (such as when a vehicle is at stop) and thus mechanical drive 12 to be stopped and to still have the electrical drive 14 operate to maintain operation of the pump 16 to maintain fluid pressure supplied to the gallery of the engine and thereby maintain hydraulic pressure supply to various engine components such as a cam phase unit.

Thus, in the exemplary embodiments disclosed and taught herein, a fluid pump 16 using both a mechanical drive 12 and an electrical drive 14 to sequentially and/or simultaneously operate the inner 40 and outer 38 rotors for the pumping of the fluid is accomplished.

The present disclosure is described in an illustrative manner. It is to be understood that the terminology used is intended to be in the nature of words of description used in the broadest sense or meaning, unless otherwise stated, rather than in a limited or narrow interpretation. It is also to be understood that many modifications and variations of the present disclosure are possible in light of the above disclosures and teachings. Therefore, it should be readily understood that the invention claimed below may be practiced other than as specifically described and still be covered by the following claims.

Claims

1. A pump comprising: a housing having an inlet for receiving a supply of a fluid and an outlet for supplying the fluid at a pressure higher than the pressure of the fluid at the inlet;a mechanical drive coupled to the pump for operating the pump; andan electrical drive coupled to the pump for operating the pump wherein selectively the mechanical drive, the electrical drive or both mechanical and electrical drives may be used independently or in conjunction to operate the pump and control its fluid output.

2. The pump of claim 1 wherein the mechanical drive and the electrical drive are independently controllable.

3. The pump of claim 1 wherein the mechanical drive and electrical drive are independently operable at the same time.

4. The pump of claim 1 wherein the mechanical drive operates at a speed dependent upon the speed of an engine and the electrical drive operates at a speed independently of the speed of the engine.

5. The pump of claim 1 further comprising a variable displacement vane pump including a first inner rotor and a second outer rotor and wherein the mechanical drive comprises a shaft coupled to one of the inner rotor and outer rotor and the electrical drive includes an electric motor coupled to the other of the inner rotor and the outer rotor.

6. The pump of claim 1 wherein the mechanical drive is adapted to be coupled to a power takeoff from an engine.

7. The pump of claim 1 wherein the mechanical drive is a power takeoff from an engine.

8. The pump of claim 2 wherein the pump is a variable displacement pump is selected from a binary pump, vane pump, gerotor pump, axial piston pump, rotory valve and bent axis pump.

9. A variable displacement oil pump for use in supplying oil to a powertrain of a vehicle, the pump comprising: a pump housing having an inlet for receiving a supply of a fluid and an outlet for supplying the fluid at a pressure higher than the pressure of the fluid at the inlet, the pump housing including a passage;an inner rotor located in the pump housing;an outer rotor located in the pump housing, the outer rotor including an engagement portion aligned with the passage in the pump housing, said inner rotor and said outer rotor being configured to pump fluid during relative rotational motion between said inner rotor and said outer rotor;an electric motor including a drive member for coupling to the engagement portion of the outer rotor for providing selective rotation of said outer rotor; anda mechanical drive coupled to the inner rotor for rotation of the inner rotor and operating of the pump.

10. The variable displacement oil pump for use in supplying oil to a powertrain of a vehicle of claim 9 wherein the movement of the inner rotor by way of the mechanical drive supplies torque to the electric motor for generating energy during preselected conditions.

11. The variable displacement oil pump for use in supplying oil to a powertrain of a vehicle of claim 10 further comprising an energy storing device for storing energy generated during said preselected conditions.

12. The variable displacement oil pump for use in supplying oil to a powertrain of a vehicle of claim 11 further comprising a controller including a four quadrant electrical motor driver capable of controlling speed and direction of motor rotation and direction of motor torque.

13. The variable displacement oil pump for use in supplying oil to a powertrain of a vehicle of claim 12 wherein the controller further comprises a first quadrant where motor rotation and torque are aligned in a first direction for pumping fluid and a second quadrant wherein motor rotation is in said first direction and torque is in an opposite second direction for generation of energy and supplying electrical energy to said storage device.

14. The variable displacement oil pump for use in supplying oil to a powertrain of a vehicle of claim 13 wherein the controller further comprises a third quadrant where motor direction and torque are aligned in said second opposite direction and a fourth quadrant of control wherein motor rotation is in a second direction and torque is in a first direction for generating and supplying energy to said electrical storage device.

15. The variable displacement oil pump for use in supplying oil to a powertrain of a vehicle of claim 14 wherein said energy storage device is selected from a battery, a capacitor or a combination thereof.

16. The variable displacement oil pump for use in supplying oil to a powertrain of a vehicle of claim 9 wherein said mechanical drive is a power takeoff of an engine.

17. A pump, comprising: a housing having an inlet for receiving a supply of fluid and an outlet for supplying the fluid at a pressure higher than the pressure of the fluid at the inlet;an outer rotor including an internal passage;an inner rotor for being driven by a driveshaft, the inner rotor including a plurality of radially extending, outwardly biased vanes slidably disposed in the inner rotor;an electrical drive coupled to the pump for operating the pumpwherein the inner rotor is located within the internal passage of the outer rotor and the inner and outer rotors my each be independently operated.

18. The pump of claim 17 wherein the inner passage of the outer rotor is shaped to move the biased pump fins toward a central axis of the pump as the inner rotor rotates relative the outer rotor.

19. The pump of claim 18 wherein the inner passage of the outer rotor has a generally elliptical shape.

20. The pump of claim 18 wherein the fins of the inner rotor are moved if the inner rotor is rotated.

21. The pump of claim 18 wherein the fins of the inner rotor are moved if the outer rotor is rotated.

22. A method of pumping oil in a powertrain of a vehicle comprising the steps of: a. providing variable displacement oil pump for use in supplying oil to a powertrain of a vehicle, the pump which includes a pump housing having an inlet for receiving a supply of a fluid and an outlet for supplying the fluid at a pressure higher than the pressure of the fluid at the inlet, the pump housing including a passage;a first pumping rotor located in the pump housing;a second pumping rotor located in the pump housing such that relative rotation between the first pumping rotor and the second pumping rotor results in pumping of the fluid; andan electric motor for driving one of said first rotor or second rotor and a separate mechanical drive for rotationally driving said second rotor,b. providing a controller for selectively operating the electric motor for providing pumping action during preselected conditions.

23. The method of claim 22 wherein the controller varies an output pressure that can be selected from a continuous range of pressures, independent of the operating speed of the mechanical drive of the pump and without the use of a pressure relief valve.

24. The method of claim 22 wherein said first rotor is an inner rotor rotational in the second rotor which is an outer rotor and the mechanical drive is operated to move the inner rotor of the pump to pump the oil from the inlet to the outlet.

25. The method of claim 24 wherein the electrical drive is operated to move the rotor of the outer rotor of the pump to pump the oil from the inlet to the outlet.

26. The method of claim 25 wherein the mechanical drive and the electrical drive are operated at the same time to move the inner and outer rotors of the pump to pump the oil from the inlet to the outlet.

27. The method of claim 26 wherein the mechanical drive is operated to move a first rotor in a first direction and the electrical drive is operated to move a second rotor to pump the oil from the inlet to the outlet.

28. The method of claim 27 wherein the electrical drive is operated using a four quadrant control strategy wherein said controller includes a four quadrant electrical motor driver capable of controlling speed and direction of motor rotation and direction of motor torque.

29. The method of claim 28 wherein the controller further comprises a first quadrant where motor rotation and torque are aligned in a first direction for pumping of fluid and a second quadrant wherein motor rotation is in said first direction and torque is in an opposite second direction for generation of energy and supplying electrical energy to an energy storage device.

30. The method of claim 29 wherein the controller further comprises a third quadrant where motor direction and torque are aligned in said second opposite direction and a fourth quadrant of control wherein motor rotation is in a second direction and torque is in a first direction for generating and supplying energy to said electrical storage device.

31. The method of claim 30 wherein said energy storage device is selected from a battery, a capacitor and a combination thereof.