WO2012047223A1

WO2012047223A1 - Electric hydraulic power steering pump and method of making same

Info

Publication number: WO2012047223A1
Application number: PCT/US2010/051856
Authority: WO
Inventors: Daniel Gizaw; Germa Desta; Selamsew Tilahun Worku
Original assignee: Danotek Motion Technologies
Priority date: 2010-10-07
Filing date: 2010-10-07
Publication date: 2012-04-12

Abstract

A power steering assembly includes a housing for a current generating motor having a rotor and a stator. A controller housing secured to an end of the motor housing contains a controller having a processer, is secured to a heat sink forming an end of the assembly. A pump is located on the opposed end of the motor housing and operatively connects to the motor shaft. An executable software program in the controller checks operation of the motor and modifies the output of the motor if the first predetermined operating condition and continues to check the operating condition and modify motor power output. A fixture assembles the rotor to the stator using a plunger assembly mounted to the based plate, and moveable in a forwardly direction to secure the rotor as the slide plate travels along rails to assemble the rotor into the housing and stator.

Description

ELECTRIC HYDRAULIC POWER STEERING PUMP AND METHOD

OF MAKING SAME

FIELD

[0001] The present invention relates to an electric hydraulic power steering pump, and in particular to an electric hydraulic power steering pump for an electric vehicle and a method of making the same.

BACKGROUND OF THE DISCLOSURE

[0002] Vehicles incorporate a steering system for transferring operator input to the wheels of the vehicle in order to control the movement of the vehicle. Various types of steering systems are known, such as a power assisted steering system. The power assisted steering system may include an electro-hydraulic device that provides power assisted steering. The electro- hydraulic device typically includes an electric motor and a hydraulic pump, and the electric motor rotates an input shaft of the hydraulic pump to supply pressurized hydraulic fluid to a steering gear. The steering gear is operatively connected to the vehicle's wheels and controls the movement of the same. The hydraulic fluid may be returned to a reservoir connected to the hydraulic pump for reuse.

[0003] The power steering system utilizes a predetermined amount of energy. In certain types of vehicles, it may be desireable to reduce energy consumption and improve the power distribution efficiency of the vehicle, such as in a hybrid or electrically controlled vehicle. In addition, the electro-hydraulic power steering system may be affected by parameter variations that impact the overall system operation. For example, temperature fluctuation, such as due to the generation of heat, may influence the operation and resulting performance of the electro- hydraulic power steering system. In addition, the electro-hydraulic power steering system may be subject to various environmental operating conditions. Thus, there is a need in the art for an electro-hydraulic power steering pump that includes a permanent magnet brushless motor and a motor controller in a single, compact package, and that the integral package is robust under various operating conditions.

[0004] An advantage of the present disclosure is that an electro-hydraulic power steering system is provided in a compact package that is impervious to environmental conditions. Another advantage of the present disclosures is that an electro-hydraulic power steering system is provided that operates efficiently and can be easily maintained. Still another advantage of the present disclosure is that an electro-hydraulic power steering system is provided that efficiently dissipates heat. A further advantage of the present system is that a method of making an electro-hydraulic power steering pump is provided that is cost- effective.

SUMMARY

[0005] A power steering assembly includes a cylindrical motor housing for a motor, having a rotor that rotates about a centrally located shaft and a stator spaced a distance from the rotor. A controller housing is secured to an end of the motor housing. The controller housing includes a controller having a processer and that is secured to a heat sink that forms an end of the assembly. A pump is located on the opposed end of the motor housing and operatively connected to the motor shaft. [0006] A fixture for assembling a power steering assembly includes a base plate having a first and second end wall and two rails positioned on an upper surface of the base plate between each of the first and second end walls. A generally rectangular slide plate is movable along the rails, a clamping means secures the motor housing to the slide plate. A plunger is secured to the based plate, such that the plunger is moveable in a forwardly direction toward the housing to insert the other end of the rotor assembly into the plunger as the plate travels along the rails to assemble the rotor and stated together.

[0007] A method of controlling a power steering pump assembly includes the steps of initializing variables, checking operation of the motor and setting a flag if a first predetermined operating condition is met. Power output of the motor is reduced if the first predetermined operating condition is met. The method continues to check the operating condition and reduce motor power output until a second the predetermined operating condition is met.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a perspective view of an electro-hydraulic power steering pump for a vehicle, according to an exemplary embodiment.

[0009] FIG. 2 is a sectional view of an electro-hydraulic power steering pump of FIG. 1.

[0010] FIG. 3 is a perspective view of a stator of FIG. 2, according to an exemplary embodiment.

[0011] FIG. 4 is a perspective view of a rotor assembly of FIG. 2, according to an exemplary embodiment. [0012] FIG. 5 is a perspective view of the permanent magnets that are attached to the outside surface of the rotor, according to an exemplary embodiment.

[0013] FIG. 6 is a perspective view of the controller assembly of FIG. 2, according to an exemplary embodiment.

[0014] FIG. 7. is a perspective view of the pump assembly of FIG. 2, according to an exemplary embodiment.

[0015] FIG. 8 is a perspective front view of an electro-hydraulic power steering pump partially assembled and attached to a fixture, according to an exemplary embodiment.

[0016] FIG. 9 is a perspective side view of an electro-hydraulic power steering pump partially assembled and attached to a fixture, according to an exemplary embodiment.

[0017] FIG. 10 is a perspective side view of the outer motor housing and controller housing, according to an exemplary embodiment.

[0018] FIG. 11 is a flow-chart detailing the methodology for making the electro-hydraulic power steering pump of FIG. 1, according to an exemplary embodiment.

[0019] FIGS. 12A-12D is a flow-chart detailing the methodology for controlling the operation of the steering pump assembly, according to an exemplary embodiment.

DETAILED DESCRIPTION

[0020] Referring generally to the FIGURES and particularly to FIG. 1, an electro-hydraulic power steering assembly 10 for a vehicle is shown. In this example, the vehicle system is a motor vehicle that contains a power source. Various types of power sources are contemplated, such as a conventional gasoline engine, an electric vehicle, or a hybrid vehicle that utilizes more than one energy source or another power source. The electro-hydraulic power steering pump assembly 10 includes a motor 12, controller 14 and pump 16 in an integral, compact package.

[0021] Referring now to FIGS. 2-7 the assembly 10 includes an outer motor housing 18 which contains the motor 12, controller 14 and pump 16. The housing 18 is made of a material such as a plastic, or a metal or the like. In this example the housing 18 is an aluminum material. The outer motor housing 18 may be machined or extruded, according to the material used. Depending on the packaging of the assembly 10 within the vehicle, the housing 18 may be subjected to various operating conditions. The outer housing 18 selectively has sufficient thickness to withstand various environments and protect the contents therein. Also in this example the housing 18 has a generally cylindrical shape with a centrally located passageway 20.

[0022] The assembly 10 also includes a permanent magnet brushless motor 22 and is disposed within the motor housing 18. The motor 22 includes a stator 24 that is adjacent the housing 18. The stator 24 has a generally cylindrical shape, as shown in FIG. 3. A rotor assembly 26, as shown in FIG. 4, is positioned within the stator 24, and is separated from the stator 24 by an air gap 28. The rotor assembly 26 includes a hub 30 and shaft 32. One end of the rotor shaft 32 is supported by a bearing 34. The other end of the rotor shaft 32 is supported by an output shaft 36 in communication with a transmission device 38 which fits into the recessed portion 40 of the rotor 26. A plurality of permanent magnets 42 are mounted directly to the outside surface 44 of the rotor 26, as shown in FIG. 5. In this example, the rotor 26 includes magnets 42 with alternating North- and South- magnetic poles 46, 48 along the circumference of the rotor 26. Each magnetic pole 46, 48 extends the length of rotor 26, and is slightly skewed along the length of the rotor 26. The orientation of the magnetic poles 46, 48 improves the BEMF wave shape and reduces cogging. The permanent magnets 42 are attached to the rotor 26 by various techniques, such as a combination of adhesive, mounting clips, and a high strength wrap of fiberglass or carbon fiber or the like.

[0023] The stator 24 is formed using a stack of thin iron laminations 50. Each lamination 50 has alternating teeth 52 and slots 54. In this example there are 12 teeth 52 and 12 slots 54, although other configurations are contemplated. Insulated copper wire 56 is placed within each of the slots 54. The winding is wound in a 3-phase 22 pole pattern. Each tooth 52 of the stator 24 contains a shoe 58 having 2 or 3 sub-teeth 60 that face the air gap 28. The sub-teeth 60 combined with the skew on the rotor 26 reduce the cogging torque.

[0024] The rotor 26 and stator 24 may be cooled using a medium, such as air or a liquid. The cooling medium may enter the motor housing 18 via an inlet port and/or an outlet port that is in communication with a cooling channel that provides for cooling of the motor 12. The cooling medium, such as water or glycol is circulated so that internal heat generated in the stator 24 is dissipated through the cooling medium.

[0025] The assembly 10 also includes a controller assembly 72, as shown in FIG. 6, that is operatively in communication with the motor 12 and other vehicle controllers via a communication device 74, such as through a CAN bus. The assembly 10 is disposed within a controller housing 76 that is a generally cylindrical member, and an end of the motor housing 18 is connected to an end of the controller housing 76 using a fastener 78, such as a screw or bolt or the like. There may be a gasket 80 placed between the motor housing 18 and controller housing 76 to seal the interiors of the motor housing 18 and controller housing 76. The sealed motor and controller assembly 18, 76 is protected from the elements.

[0026] The controller 72 includes a printed circuit board 82 having various electrical components 84 mounted thereto in a predetermined manner. Examples of electrical components 84 include a processor and a memory, to be described. A communication device 74, such as a wiring harness, or CAN bus, is operatively connected to the controller 72.

[0027] The controller 72 controls the operation of the motor 12. Examples of operations include diagnostics, and automatic power control. The controller 72 may store information for other uses. In addition, the controller 72 may control performance of the electro-hydraulic pump 16 by calculating the rotor 44 position of the motor 12 without the use of mechanical sensors, performing diagnostics of the motor 12 or pump 16 or controller 14, or by communicating with other vehicle systems. The controller 72 receives inputs from various other sensing devices within the vehicle, such as ambient temperature, vehicle speed, fuel delivery or the like. The processor analyzes these inputs and transmits an output signal that is utilized in the operation of the pump assembly 16.

[0028] The processor may contain a microchip as is known in the art. The microchip contains a central processing unit (CPU), a peripheral drive control, and memory. The microchip contains various types of memory, including volatile and nonvolatile memory. The memory may be further subdivided into RAM, a code flash memory, a data flash memory or the like. It should be appreciated that the contents of certain types of memory may updatable.

[0029] The controller 72 is secured to a heat transfer member 98, such as a T-bar, and the T-bar is attached to a heat sink 100, such as by an adhesive or bolting or the like. The heat sink 100 is a plate 102 having a plurality of fins 104 extending therefrom, and may be fabricated from a high temperature conductive material. The fins 104 are arranged on the plate 102 in a predetermined manner so that a pathway is provided for cooling the controller 72. The heat transfer member 98 provides a path to the heat sink 100 as shown at 106.

[0030] For example, the controller 72 may be secured so that it stands off from the heat transfer member 98. Through holes 108 may be used to mechanically attach the heat transfer member 98 to the heat sink plate 102. The controller 72, heat sink member 98 and heat sink plate 102 are disposed in the controller housing 76 so that fins 104 are exposed. The controller assembly 72 is secured to the controller housing 76, such as by a fastener 78 or the like.

[0031] The assembly 10 further includes a hydraulic pump 16, shown in FIG. 7, disposed on the opposite end on the motor housing 18. The steering pump 16 is conventionally known for use in vehicles. The pump 16 is attached to the housing 18, such as by a fastener 78. A gasket 1 10 may be positioned between the motor housing 18 and the pump 16.

[0032] To operate the power steering assembly 10, a slow-speed torque input is applied to the rotor 26, such as via a top flange. The rotor 26 rotates about the stator 24 on the bearings 34, and the motion of the magnets 42 passing the coiled lamination stack 50 produces electrical current in the coiled wires 56. The pump 16 is operatively connected to the motor output shaft 36 in order to operate the pump 16. The pump 16 transfers fluid to the steering gear to assist in transferring the movement of the steering wheel by a vehicle operator to the wheels. The electrical current generated by the motor is utilized to operate the pump and control operation of the controller 14 in a manner to be described.

[0033] FIGS. 8-11 show and describe the method of making the power steering assembly 10. Referring particularly to FIG. 11 , a method of assembling the power steering assembly 10 is described at 200. The method begins in block 205 with the step of preparing a motor housing 18, which in this example has a generally cylindrical shape. A wall of the housing 18 includes a plurality of apertures, such as three, located near a lower end of the wall. The housing 18 may be placed in an oven and heated to a predetermined temperature, such as 350 deg. for a predetermined period of time, such as 25 minutes in order to pretreat the housing 18.

[0034] The methodology advances to block 210 and the stator 24 is prepared, such as by placing the stator on a fixture for building the stator/rotor subassembly. An example of a fixture is a base plate with a ring portion for receiving the stator. The fixture may hold a plurality of stators in order to improve the assembly technique. The stator 24 may be positioned so that the end turns are not touching the fixture, and oriented so that lead wires are all facing the same side of the fixture, such as the right side during assembly.

[0035] The methodology advances to block 215 and the housing 18 is placed over the prepared stator 24 and aligned. For example, the housing 18 is rotated so that the apertures are facing in a downwardly direction. The housing 18 may be lowered over that stator 24, until a lip within the center of the housing 18 is adjacent the uppermost edge of the stator core.

[0036] The methodology advances to block 220 and the housing 18 is secured to the stator 24. For example, the housing 18 may be secured using a fastener 78 extending therethrough the apertures in the housing 18, such as an upper aperture and a lower aperture. [0037] The methodology advances to block 225 and assembles the bearings 34 to the rotor 26. For example, a lower bearing is placed within the housing towards the bottom of the base fixture. The rotor assembly 26 is positioned in the base fixture with the slotted end of the shaft facing up. Using a tool such as an arbor press, the shaft 32 is centered over the lower bearing and the arbor is moved in a downwardly direction in this example so that the shaft 32 engages the lower bearing. The shaft of the rotor assembly 32 is disposed within a central opening in the lower bearing. An upper bearing is positioned over the upper end of the shaft. A bearing upper fixture is positioned onto the bearing 34. Using an arbor press, the shaft 32 is centered and the arbor press is moved in a downwardly direction to engage the upper bearing to the shaft 32. The position of the upper and lower bearings may be verified using a gauge.

[0038] The methodology advances to block 230 and the front bell 110 is assembled to the motor housing 18. For example, the housing/stator assembly is rotated until the three apertures are at the top. A gasket is positioned on the upper surface of the housing. Apertures in the upper surface of the housing line up with corresponding apertures in the gasket. The front bell 1 10 is positioned over the gasket to close the upper end of the housing and secured thereto. For example, it is secured using bolts. The methodology advances to block 235 and the end bell 11 lis prepared. For example, a grommet is placed into a channel in the end bell 1 11. A gasket is positioned on a surface of the end bell 11 1.

[0039] The methodology advances to block 240 and the rotor 26 is assembled to the stator 24 using a fixture. As shown in FIG. 8 and 9, the rotor fixture 400 includes a generally rectangular base plate 402, and two parallel end walls 404 extending perpendicular to the base plate. A rail 406 is positioned on an upper surface of the base plate 402, and oriented between each of the end walls 404, and in this example there are two rails 406 spaced a predetermined distance apart. A generally rectangular slide plate 408 is positioned on the rails 406 and is movable along the rails. The slide plate 408 supports the motor housing. The rotor fixture 400 may also include a stop 410 used to align the housing with respect to the slide plate 408. The housing is placed on the slide plate, and secured thereto using a securing device 412. For example, the housing may be clamped to the slide plate using a clamp. In this example, the housing holes are positioned to face the operator, and the slide plate 408 is initially adjacent a first wall 404a in a home position. The rotor fixture also includes a plunger assembly 414 disposed on the base plate. The plunger assembly 414 includes a plunger 416 that is moveable between a first position and a second position. The plunger is supported by the end wall 404a at one end and a support wall 418 at a second end. The plunger assembly also includes an operating mechanism 420, such as a handle of this example, for selectively moving the plunger 416 in a manner to be described. The plunger assembly may be manually operated or utilize a motor in order to be automated.

[0040] The methodology advances to block 245 and the end bell 1 11 is placed on the fixture 400. The end bell 1 1 1 is positioned on the opposed second wall 404b. For example, the end wall 1 11 may have fixture pins that receive the end bell. A wave spring may be positioned in a bearing pocket on the end bell.

[0041] The methodology advances to block 250 and the motor 12 is assembled. The rotor assembly 26 is mounted to the second end wall 404b of the fixture and positioned to be received within the housing. In this example, the slotted end shaft of the rotor assembly 26 is inserted into the bearing pocket on the end bell 1 1 1 to support the rotor. The plunger 416 is moved in a forwardly direction through the housing, and inserted into the other end of the rotor assembly 26. The plunger 416 is locked onto the rotor assembly 26 using a locking mechanism 420. For example, a clamp 420 is engaged to lock to plunger 416 to the rotor 26. The lead wires are positioned, such as by pulling the lead wires through the grommet to fully extend the wires. In this example there are two lead wires. The lead wires a positioned by locating within a cut out portion of the end wall, which in this example is u-shaped. Any slack in the wires is removed. The slide plate 408 is displaced along the rails 406, by movement of the slide plate 408, such that the rotor 26 and stator 24 are assembled together. The end bell 11 1 is secured to the housing, such as by using a screw.

[0042] The methodology advances to block 255 and the assembly 10 is removed from the fixture. For example, the plunger 416 is unlocked and the motor assembly 10 is removed from the rotor fixture.

[0043] The methodology advances to block 260 and the controller housing 76 is prepared. For example, the wiring harness is secured within the controller housing 76. Similarly, the signal harness is also secured within the controller housing 76.

[0044] The methodology advances to block 265 and the motor housing 18 is secured to the controller housing 76. For example, the stator housing assembly is oriented so that the mounting holes are facing in a downwardly direction. A gasket may be positioned between the motor housing 18 and the controller housing 76. The controller housing 76 is secured to the motor housing 18, such as by a fastener 78.

[0045] The methodology advances to block 270 and the controller 14 is prepared. For example, pin connections are made and ground strips positioned on the printed circuit board 82. The controller wiring is connected to the motor housing lead wires. [0046] The methodology advances to block 275 and the controller assembly 72 is positioned within the controller housing 76 and secured thereto using a fastener 78, such as a screw or the like. It should be noted that the fins 104 are exposed beyond the controller housing 76.

[0047] The methodology advances to block 280 and the pump 16 is secured to the opposite end of the motor housing 18. For example, the motor output shaft 36 is aligned with a corresponding receiving portion of the pump 16. The pump 16 is secured using a fastener 78, such as a screw. Other connections are made to the pump 16. For example, the ports 62, 64 for the hydraulic fluid and lines are secured to the pump 16.

[0048] The pump assembly 16 may be tested to confirm operation and other quality review procedures. For example, an end of line test may be performed after the power steering pump assembly 16 is assembled together. This may be a self test.

[0049] Referring now to Fig. 12, a methodology for controlling the operation of the steering pump assembly 16 is illustrated. The methodology is implemented by firmware embedded in the controller 14, and such that associated with the memory and processor. The methodology uniquely stabilizes the system if a fault is detected while still providing the vehicle operator with some power steering assistance. The methodology stores information learned and may communicate information, such as diagnostic information to the vehicle operator.

[0050] The methodology begins in block 300 and initializes variables. An example of a variable is a vehicle operating condition such as idle. The methodology advances to block 305 and configures modules and communication ports within the hardware. The modules and communication ports define what the various functions of the steering pump assembly. [0051] The methodology advances to block 310 and checks the hardware operating conditions. For example, an over voltage or an over current condition may be checked and compared to a predetermined level. The methodology advances to block 312 and a corrective action occurs. An example of a corrective action is that if a fault is detected, the detected fault may be reset to a predetermined operating value. If a fault is not detected, the methodology advances to block 314 and sets an indicator such as a flag. The methodology advances to block 315 and performs a check of the motor to insure its operation. For example, the methodology may call a subroutine that performs a diagnostic check of the motor. The methodology advances to block 320 and determines if a fault is detected in the motor 12. If a fault is detected, the methodology advances to block 322 and a flag may be set indicating a fault and the operator is alerted. The methodology advances to block 325 and clears flags used in tracking the operating status of the assembly.

[0052] The methodology advances to block 330 and determines if a reduced system performance flag is set. The reduced system performance flag modifies the operation of the power steering assembly 10 to maintain or enhance performance. For example, if the Reduced Performance flag is set, the methodology advances to block 334 and executes a reduced performance methodology. For example, if the temperature is greater than a predetermined temperature, the power output of the motor 12 may be limited to reduce the amount of power, i.e. reduce power by one half if over temperature. The system may check power again, and reduce power by one half again. This can be done iteratively a preset number of times, and then the motor can be shut off if the condition continues. If the reduced system performance flag is not set, the methodology advances to block 332 and resets the reduced performance variables.

[0053] The methodology advances to block 335 and the status of the electric hydraulic power assisted pump 16 is checked. For example the status may be checked for a fault, or whether it is ready to be turned on, or the like. The methodology advances to block 340 and it is determined if diagnostics of the power steering assembly 10 is requested. If diagnostics is requested, then the methodology advances to block 342 and executes a predetermined diagnostics routine. If diagnostics is not reported, the methodology advances to block 345. In block 345 the methodology determines if a power mode meets predetermined criteria. For example, if the power mode meets predetermined criteria the pump 16 will run. If the power mode does not meet predetermined criteria, then the methodology advances to block 348 and restart parameters and input values are reset.

[0054] The methodology advances to block 350 and the state of the pump 16 is evaluated. For example a counter for the session may be compared to the pump state. If there is a fault detected, then certain activities are performed within a designated session. The methodology advances to block 355 and the operations state is updated to be consistent with the power mode.

[0055] The methodology advances to block 360 and the state is evaluated. An example of a state is idle 360a, start 360b, run 360c, stop 360d or fault 360e. Depending on the detected state, a corresponding routine is executed as shown as 362a, 362b, 362d and 362e. The states may be sequentially executed. The methodology advances to block 365 and determines whether the time for operation of the steering pump assembly 10. The methodology advances to block 370 and compares the operation time to a predetermined status time for performing a preset operation. An example of a preset operation is to send a status signal to a controller 14. If the operation time is over, the methodology advances to block 375 and communicates the electric hydraulic power assisted pump states. For example, the methodology will update various diagnostics travel parameters. The methodology advances to block 380 and updates the current limit. The methodology advances to block 385 and determines if the DTC setting is enabled. If the DTC setting is enabled, the methodology advances to block 390 and updates the DPC parameters. The methodology returns to block 310 and continues.

[0056] Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings.

[0057] Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.

Claims

WHAT IS CLAIMED IS:

1. A power steering assembly comprising:

a housing for a motor, wherein the motor includes a rotor that rotates about a centrally located shaft and a stator spaced a distance from the rotor to generate an electric current;

a controller housing secured to an end of the motor housing, wherein the controller housing includes a controller having a processer for controlling the power steering assembly using the generated current and that is secured to a heat sink that forms an end of the assembly; and

a pump located on the opposed end of the motor housing and operatively connected to the motor shaft and in communication with the controller .

2. The power steering assembly of Claim 1, further comprising a gasket placed between the motor housing and the controller housing for sealing the interiors of the motor housing and the controller housing from the exterior environment.

3. The power steering assembly of Claim 1, wherein the rotor includes magnets with alternating North-South magnetic poles along the circumference of the rotor and wherein each magnetic poles extends the length of the rotor and is slightly skewed along the length of the rotor.

4. The power steering assembly of Claim 1, wherein the stator is formed from a stack of iron laminations having alternating teeth with a plurality of sub-teeth and slots having insulated copper wire.

5. The power steering assembly of Claim 4, wherein the insulated copper wire is wound in a 3 -phase 22 pole pattern.

6. The power steering assembly of Claim 1, wherein the controller includes a printed circuit board having a plurality of electrical components mounted thereon and a communication device operatively connected to the controller.

7. The power steering assembly of Claim 1, wherein the processor includes a memory, and an executable software program for operating the power steering assembly is stored within the memory.

8. The power steering assembly of Claim 7 wherein the software program determines if there is a fault within the power steering assembly and modifies pump operation if a fault is detected.

9. The power steering assembly of Claim 7 wherein the software program evaluates a predetermined state of the pump and modifies operation of the pump according to the predetermined state.

10. The power steering assembly of Claim 1, wherein the heat sink includes a plate having a plurality of fins extending therefrom such that a pathway for cooling the controller is created.

11. A fixture for assembling a power steering assembly comprising:

a base plate having a first end wall and second end wall, wherein a rotor is temporarily mounted to the second end wall; a rail positioned on an upper surface of the base plate between the first end wall and second end wall;

a generally rectangular slide plate movably positioned on the rail, wherein a motor housing having a stator, is positioned on the slide plate;

a clamping means for securing the motor housing to the slide plate; and

a plunger assembly mounted to the based plate, such that the plunger is moveable in a forwardly direction toward the second end wall and secured to the rotor as the slide plate travels along the rails to assemble the rotor into the housing with the stator.

12. The fixture for assembling a power steering assembly of Claim 1 1 , wherein an end bell is mounted on the second end wall and the rotor is mounted on the end bell.

13. A method of controlling a power steering pump assembly, said method comprising the steps of:

providing a power steering pump assembly having a motor that includes a rotor that rotates about a centrally located shaft and a stator spaced a distance from the rotor to generate an electric current, a controller housing secured to an end of the motor housing for receiving a controller having a processer for controlling the power steering assembly using the generated current and the controller is secured to a heat sink that forms an end of the assembly, and a power steering pump located on the opposed end of the motor housing that is operatively connected to the motor shaft;

checking operation of the motor and setting a flag if a predetermined operating condition is met, wherein the power output of the motor is modified if the first predetermined operating condition is met; and continuing to check the operating condition and modify motor power output until a second the predetermined operating condition is met.

14. The method of claim 13 further comprising the step of initializing variables associated with the power steering pump assembly.

15. The method of claim 13 further comprising the step of determining if a third predetermined operating condition met, and initiating a corrective action if the predetermined operation condition is met.

16. The method as set forth in claim 15 wherein the third predetermined operating condition is a fault in the power steering pump assembly.

17. The method as set forth in claim 13 further comprising the step of executing a predetermined diagnostics routine of the power steering pump assembly and modifying operation of the power steering pump assembly if the first predetermined operating condition is detected.

18. The method as set forth in claim 13 further comprising the step of determining if a third predetermined operating condition of reduced performance is met, and the power is reduced by a predetermined amount if the reduced performance operating condition is met.

19. The method as set forth in claim 13 further comprising the step of determining if a third predetermined operating condition of an operating state of the pump is met, and the operation of the pump is modified according to the operating state of the pump.

20. The method as set forth in claim 13 further comprising the step of determining if a third predetermined operating condition of a power mode is met, and the operation of the pump is modified according to the detected power mode.