Motor control apparatus, power steering apparatus and brake control apparatus

A motor control apparatus includes a motor, and a control system board supporting a control circuit to control the motor. The apparatus may further include a power system board supporting a power supply circuit to supply power to the motor. The control system board includes a first board portion facing in a direction along a rotation axis of the motor, and a second board portion extending radially from the first board portion.

BACKGROUND OF THE INVENTION

The present invention relates to motor control apparatus which can be used for a vehicle power steering system, a vehicle brake system etc.

A United States Patent Application Publication US 2003/0173920 (≈U.S. Pat. No. 6,906,483B2≈JP2003-3267233A) shows electric power steering apparatus including a motor and a motor control system board enclosed in a board housing.

SUMMARY OF THE INVENTION

However, the board housing of the electric power steering apparatus of this US publication is so provided as to increase the entire size of the apparatus.

It is an object of the present invention to provide motor control apparatus which is simplified in construction and compact.

According to one aspect of the present invention, a motor control apparatus comprises: a motor including a rotating member; and a control system board supporting a component of a control circuit to control the motor, and including a first board portion facing in a direction along a rotation axis of the motor, and a second board portion extending radially from the first board portion.

According to another aspect of the invention, the motor control apparatus further comprises an actuating section connected with the motor to receive torque from the motor. The control apparatus may be a power steering system or a brake control system.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1˜6show a motor control apparatus or system according to a first embodiment of the present invention. The motor control apparatus includes at least a motor control section1. In the first embodiment, the motor control apparatus further includes an actuating section which is combined with motor control section1, to form an electric power steering system. In these figures, a y axis is parallel to the axial direction of the power steering system; an x axis is perpendicular to the y axis and parallel to the sheet ofFIG. 1; and a z axis is perpendicular to the sheet ofFIG. 1.

Motor control section1of this embodiment includes at least a motor100, a power system board or substrate400for supporting components of a power supply circuit, and a control system board or substrate300for supporting components of a control circuit. Motor100includes a stator110and a rotating member120including a rotor. The power supply circuit includes one or more semiconductor switching devices410which are mounted on the power system board400, and which are configured to supply power to motor100. In this example, each switching device includes an inverters410. In this example, the control circuit includes a microcomputer for controlling the inverters410, and the microcomputer is mounted on control system board300.

Control system board300includes at least a first board portion or motor side portion301, and a second board portion or outer portion302. First board portion301is provided at one end of motor100, on the z axis positive side of motor100that is the upper side of motor100as viewed inFIG. 3. First board portion301is oriented so that the axis of rotor120is perpendicular to first board portion301. Second board portion302extends radially outward from first board portion301. In this example, control system board300is a substantially flat single board, and the first and second board portions301and302are both substantially flat and substantially even (in the same plane).

Power steering system of this embodiment includes at least the above-mentioned motor control section1, an assembly housing including a first housing2aand a second housing2b, a steering input shaft3, a pinion shaft4, a worm wheel5, a worm shaft6(serving as a driven member driven by motor100), a torque sensor TS, and a rotational position sensor130. Control system board300is disposed so that worm shaft6is perpendicular to control system board300. Control system board300is connected with torque sensor TS, power system board400and rotational position sensor130which is arranged to sense the rotation of motor200.

First housing2aincludes at least a gear housing11, a motor housing12, and a power system board housing13(as best shown inFIG. 5). In the illustrated example, motor housing12and power system board housing13are integral with each other, and integral parts of a single housing. Motor housing12is provided on the z axis negative side of gear housing11(that is the lower side of gear housing11as viewed inFIG. 3). Power system board housing13is located on the z axis negative side of gear housing11, and on the x axis positive side of motor housing12(that is the right side of motor housing12as viewed inFIG. 3).

Gear housing11includes a main portion shaped like a cup having a bottom. The bottom of gear housing11faces in the y axis positive direction (that is the upward direction as viewed inFIG. 1), and is formed with a through hole11athrough which the steering input shaft3is inserted. Gear housing11includes an opening11bon the y axis negative side (that is the lower side as viewed inFIG. 1). Pinion shaft4, worm wheel5, control system board300and torque sensor TS are inserted sequentially through the opening11bof gear housing11.

Steering input shaft3is a hollow cylindrical shaft (extending in the y axis direction), and has therein a torsion bar8. Input shaft3is adapted to be connected with a steering wheel of a vehicle. Input shaft3is connected through torsion bar8with pinion shaft4. In the gear housing11, torque sensor TS is disposed around input shaft3, and arranged to sense the relative rotation between input shaft3and pinion shaft4due to a steering operation of a driver of a vehicle, and to send a signal to control system board300.

Motor housing12encloses motor100as shown inFIGS. 3,4and5, and extends in the positive direction of the z axis from a first end formed with a motor insertion opening12awhich is opened in the z-axis negative direction and which is so sized that motor100can be inserted therethrough, to a second end defined by an annular end wall formed with a sensor mounting portion12bwhich is opened in the z-axis positive direction as best shown inFIG. 5and which is so shaped that the rotational position sensor130can be mounted from the z axis positive direction (from above as viewed inFIG. 3). Motor housing12further includes a circumferential wall surrounding stator110and rotor120.

Rotational position sensor130is located adjacent to control system board300on the z axis positive side of motor housing12, and interposed between the motor housing12on the z axis negative side and the control system board300on the z axis positive side (the upper side as viewed inFIG. 3). Control system board300is disposed so that the axis of rotor120(output shaft of motor100) is perpendicular to control system board300. Rotational position sensor130is connected, by output terminals131, with control system board300. In this example, output terminals131are in the form of connecting pins which project perpendicularly from rotational position sensor130in the z axis positive direction, and which are inserted in respective pin holes formed in control system board300as shown inFIG. 5. Since rotational position sensor130is adjacent to control system board300, output terminals131can be made shorter.

Motor100of this example is a brushless motor including stator110and rotor120. Current is supplied to stator110in accordance with the rotational position of rotor120sensed by rotational position sensor130. Rotational position sensor130is fixed to the sensor mounting portion12bformed in the second end of motor housing member12, at the position confronting the axial end of rotor120on the z axis positive side. Rotational position sensor130is enclosed in first housing member2aso that the connection through output terminals131between rotational position sensor130and control system board300is made easier and more reliable. Motor100is not limited to the brushless type. Motor100may be a brush motor.

Power system board housing13is made of a heat conductive material which, in this example, is an aluminum alloy. In this example, power system board housing13is formed by aluminum die casting in order to obtain better cooling effect or improve the ability of heat dissipation. Power system board400is enclosed in power system board housing13. As shown inFIG. 2, power system board housing13includes a plurality of power system device receiving portions13aenclosing and fitting over the power system devices420,430and440, independently at respective positions. These power system devices are devices mounted on power system board400. Each of the power system device receiving portions13ais a socket like portion recessed in the z-axis negative direction (that is the upward direction as viewed inFIG. 2).

A heatsink13bis provided, as shown inFIG. 3, on the z-axis negative side of power system board housing13, at the outer circumference of the power system device receiving portions13a. Heatsink13bis designed to absorb and dissipate heat of inverters410disposed in the power system board housing13, by increasing the surface area.

The integral housing member composed of motor housing12and power system board housing13includes an end12c,13cfacing toward the control system board300on the z axis positive side. The end12c,13chas a joint surface S to which the gear housing member11enclosing the control system board300is joined. This joint surface S is substantially flat and even in the same flat plane, that is an A-A plane as shown inFIG. 3.

At the time of assembly, the power system devices420˜440are fit in the respective receiving (receptacle or socket) portions13aof power system board housing13. The receiving portions13aare designed to individually position the devices420˜440simply by insertion of the devices in the respective receiving portions13a. Accordingly, by covering the power system board400on the power system board housing member13having the power system devices fit in the respective receptacle portions13a, the power system devices can be readily set at the correct positions in the power system board400, so that soldering operation for the power system devices becomes easier.

Second housing2bcovers pinion shaft4from the y-axis negative side, and closes the opening11bof first housing2a, as shown inFIG. 1.

Control system board300is disposed between power system board400and worm wheel5, as shown inFIG. 4, and accordingly between motor100and worm wheel5. Control system board300in the form of a flat plate is parallel to the x-y plane and perpendicular to the worm shaft6. Control system board300(or the circuit of control system board300) drives motor100by outputting a drive command signal to power system board400(or the circuit of power system board400) in accordance with a steering torque sensed by torque sensor TS.

Control system board300is disposed on the z axis positive side of motor110, that is, on the side on which rotational position sensor130is located. Output terminals131of this sensor130in this example extend substantially straight in the z axis positive direction along the axis of motor100, so that the longitudinal direction of output terminals131is substantially perpendicular to the control system board300. Output terminals131is connected with control system board300substantially at right angles.

Control system board300has a motor side surface facing the motor housing member12in the z-axis negative direction, and an outer side surface facing the gear housing11in the z axis positive direction. Control system devices are mounted on both sides of the control system board300, and the circuit formed on control system board300is composed of a motor side circuit310formed on the motor side surface and an outer side circuit320formed on the outer side surface of control system board300, as shown inFIG. 2etc. Thus, both sides of control system board300are used for installation of devices, so that the area for mounting various devices is increased. The motor side circuit310and outer side circuit320are united by control system board300into a single circuit board facilitating the assembly and handling operations. Second board portion302extends radially from first board portion302. In the illustrated example, the rotating member120of motor100includes the rotor and the motor output shaft which is integral with the rotor. The motor output shaft is inserted through the through hole303.

Power system board400is disposed, in first housing2a, at a position adjacent to control system board300, and connected electrically with control system board300by harness and connectors. Power system board400and control system board300are close to each other, so that the length of the electrical connection between both boards can be reduced.

In the example shown inFIG. 5, the power supply circuit of power system board400and the control circuit of control system board300are electrically connected by connecting pins each of which includes a first pin end supported by power system board400and a second pin end supported by the second board portion302of control system board300, or inserted in a corresponding pin hole formed in control system board300.

Power system board400extends radially with respect to the axis of motor100, on the x axis positive side of motor100, as shown inFIG. 5. Power system board400overlaps the second board portion or outer portion302of control system board300. Power system board400confronts the second board portion302of control system board300along the z axis. Power system board400and control system board300extend substantially in parallel to each other side by side. Accordingly, the connection between both boards is easier.

Power system board400includes through portions403and404(as shown inFIG. 5) for receiving a power supply connector20and a signal connector30extending in the z-axis positive direction through the power board housing13and through power system board400, toward control system board300. Power supply connector20is a device for supply electric power from the outside. In this example, power is supplied to power system board400, and further supplied to control system board300via power system board400. Signal connector30is for supplying one or more signals representing vehicle operating conditions to control system board300. These connectors extend straight through housing13and power system board400toward control system board300and these connectors can reach the control system board300. Therefore, it is easy to deliver a vehicle speed signal and other vehicle operating condition signals to the circuit on control system board300, from the outside. In this example, the power system board housing13also includes through portions for receiving the power supply connector20and the signal connector30.

The power system device group mounted on power system board40includes at least relay420, capacitor430, and noise removing coil440, as shown inFIG. 2. On the x axis positive side, there is formed a dead space by a radial outer side of motor100(on the x axis positive side) and the x axis positive side portion of control system board300. Therefore, the relatively large relay420, capacitor430and noise removing coil440are installed in this dead space so as to reduce the size of the entire system.

FIG. 6shows inverters410and their vicinity more in detail. Power system board housing13includes a first end portion which has heatsink13barranged on the outer circumference and which is located on the z-axis negative side, and a second end portion which has an inverter mounting surface13don the z-axis positive side and which is formed with an opening for receiving the power system board400. This inverter mounting surface13dis substantially flat and parallel to power system board400. Wall surfaces of inverters410are held in contact with the inverter mounting surface13d. Power system board housing13is designed to absorb heat generated by inverters410from the inverter mounting surface13d, and to dissipate the heat from the heat sink13b.

A steering assist force is produced by motor100. The driving force of motor100is transmitted, through a worm shaft6which is provided on the rotation axis of motor100, to warm wheel5and which is connected end to end with the output shaft (120) of motor100in alignment. Worm shaft6is engaged with worm wheel5rotating as a unit with pinion shaft4. Pinion shaft4extends in the y axis negative direction (downward as viewed inFIG. 1) to a portion which is engaged with a rack (not shown). In this way, this steering assist system can drive the rack with a steering assist force by transmitting the driving force of motor100to the rack.

FIG. 4shows an x-z section of first housing2a. The rotating member of motor100includes a large diameter portion serving as the rotor, and a shaft portion serving as the output shaft of motor100. The output shaft of motor100is aligned and coupled with worm shaft6(driven member) by a connecting member9. Worm shaft6and rotor120are supported, at respective both ends, through bearings15and17and bearings16and18, on first housing member2a. Therefore, the positions of worm shaft6and rotor120are determined only by these bearings. Therefore, it is easier to improve the assembly accuracy simply by improving the accuracy in the positions of bearings15˜18. It is optional to employ a single integral member having an integral portion serving as the worm shaft6and an integral portion serving as rotor120.

In motor control apparatus for an electric power steering system of earlier technology, a control system board for controlling a motor is enclosed in a control board housing for the control system board, and the control board housing is a separate member distinct from a motor housing and a gear housing for a worm gear, so that the size of the entire system is increased. By contrast to this, the control system board300according to the first embodiment of the present invention is provided at one axial end of motor100(not at a circumference of motor100). Moreover, in the illustrated example, control system board300and rotational position sensor130are closely overlapped, and both sides of control system board30are used for installing circuit components. Therefore, the first embodiment is advantageous to size reduction, compactness and assembly process.

FIGS. 7˜10show a motor control apparatus according to a second embodiment of the present invention. In the second embodiment, the motor control apparatus includes a motor control section1, and an actuating section which is combined with the motor control section to form a hydraulic power steering system. In the second embodiment, the motor control section1is substantially identical to that of the first embodiment, and the actuating section includes a hydraulic power steering unit200in place of the gear housing11of the first embodiment. In the second embodiment (unlike the first embodiment), there is provided a housing cover50between the motor control section1and a pump of in the hydraulic power steering unit200.

FIG. 7shows a vehicle equipped with the hydraulic power steering system including the motor control section1, the hydraulic power steering unit200, a hydraulic cylinder40, a rack shaft41, a pinion42, steerable wheels43of the vehicle, a steering wheel SW, a torque sensor TS, a control valve V and a battery E. Hydraulic power steering unit200includes a reservoir tank or reservoir230and a hydraulic pump P. In this embodiment, a ξ (lateral) axis is an axis extending in the axial direction of the rack shaft41, a ζ (vertical) axis is a vertical axis, and a η axis is perpendicular to the sheet ofFIG. 7.

Pump P of this example is a reversible pump having first and second ports (outlet ports)210and220. Motor control section1rotates the pump P in a forward direction or in a reverse direction to produce a steering assist force. Reservoir tank230is disposed on the ζ axis positive side of motor control section1, that is on the upper side of motor control section1. Reservoir tank230is a container for storing a hydraulic fluid supplied to pump P.

The inside of cylinder40is divided, by a piston40cmoving as a unit with rack shaft41, into first and second cylinder chambers40aand40b, which are connected, respectively, through control valve V, with first and second outlet ports210and220of pump P. Rack shaft41is engaged with pinion42connected with the steering wheel SW.

In accordance with a steering torque T sensed by torque sensor TS provided in the steering linkage between steering wheel SW and pinion42, the control circuit of the control system board300in motor control section1drives the pump P with the motor100. When the hydraulic fluid is supplied by pump P driven by motor100in the direction from first cylinder chamber40ato second cylinder chamber40b, the rack shaft41moves as a unit with piston40cin the ξ axis negative direction, that is the leftward direction as viewed inFIG. 7, and provides the steering assist force to the wheels43in the ξ axis negative direction. The steering assist force in the ξ axis positive direction is produced by supply of the hydraulic fluid from second cylinder chamber40bto first cylinder chamber40a.

FIG. 8is a perspective view of the hydraulic power steering unit200which is a single unit including pump P and reservoir tank230. The hydraulic steering unit200according to the second embodiment is further shown inFIG. 9(front view in the η axis direction),FIG. 10(front view in the ξ axis direction),FIG. 11(front view in the ζ axis direction),FIG. 12(partial sectional view in a ξ-ζ plane), andFIG. 13(sectional view in a ξ-ζ plane).

Motor control section1of the second embodiment is identical in construction to the motor control section1employed in the first embodiment. Motor control section1is connected with pump P instead of gear housing11. The z axis extending in the axial direction of motor100is directed in the same direction as the ζ (vertical) axis, and the x axis is directed in the same direction as the ξ (lateral) axis. Thus, the ξ-ζ-η coordinate system coincides with the x-y-z coordinate system in the first embodiment.

As in the first embodiment, the control system board300in motor control section1of the second embodiment is provided on the z axis positive side that is the ζ (vertical) axis positive side (upper side) of motor100, as best shown inFIGS. 12 and 13so that the axis of rotor120is perpendicular to control system board300. Motor housing12and power system board housing13are integral parts of a single housing. A joint surface S between the housing (12,13) ant pump P is a flat (horizontal) surface B-B.

Motor housing12is disposed on the z axis negative side (lower side) of pump P. Power system housing13is disposed on the z axis negative side (lower side) of pump P, and on the x axis positive side of motor housing12. Pump P of this example is a trochoid pump. However, pump P may be of other types.

The rotational position sensor130is disposed on the z axis positive side of motor100, at the position adjacent to control system board300, between motor housing12and control system board300. Power system board housing13is an aluminum die casting integral with the motor housing12. Power system board housing13has the heatsink13bon the z axis negative outer side (lower side), and the power system device receiving portions13afor receiving and positioning the power system devices420,430and440independently at respective positions.

Control system board300is disposed, between power system board400and pump P, at the end of motor100on the z axis positive side, and so oriented that the axis of rotor120intersects the control system board300substantially at right angles. The output terminals131of rotational position sensor130extend in the z axis positive20direction, that is the upward direction, fittingly into respective holes in control system board300substantially at right angles. The motor side circuit310and outer side circuit320are formed on both sides of control system board300, as in the first embodiment.

Control system board300includes the first board portion301formed with the through hole303, and the second board portion302projecting radially outwards from the first board portion301. The output shaft of motor100extends upwards through the through hole303of control30system board300. The opening size or the diameter of through hole303is made small to increase the area for installation of components of the control circuit on control system board300. The diameter of the through hole303is smaller than the outside diameter of rotational position sensor130. In this example, the diameter of the through hole303is smaller than the inside diameter of a stationary annular portion of the rotational position sensor130.

Reservoir tank230is disposed on the z axis positive side, that is, the vertical upper side of the through hole303, and motor100is disposed on the z axis negative side, that is the vertical lower side, of the through hole303. A leakage of the hydraulic fluid from reservoir tank230can flow down on the output shaft120inserted upward through the through hole303, and flows through an annular clearance between the output shaft120and the through hole303, to the lower side of control system board300toward motor100. This arrangement helps protect the control system board300from being wetted by the hydraulic fluid flowing by leakage from the reservoir tank230.

Power system board400is placed horizontally, closely under the second board portion302of control system board300. In the dead space on the x axis positive side of motor housing12, the relay420, capacitor430and nose reducing coil440having relatively large volumes are supported on power system board400.

Power system board400is located on the x axis positive side of motor100, at such a circumferential position around motor100that the power system board400overlaps the second board portion302of control system board300. The power supply connector20and signal connector30are passed through the through portions403and404of power system board400, respectively. A vehicle speed signal VSP of a vehicle speed sensor44is supplied to the circuit of control system board300through signal connector30. In the second embodiment, too, one or more inverters410are mounted on power system board400, and arranged in the same manner as in the first embodiment, as shown inFIG. 6.

The housing cover50is provided between the pump P and the integral housing composed of motor housing12and power system board housing13, as best shown inFIG. 13, and arranged to close the opening defined by the z axis positive side ends12cand13cof the integral housing (12,13).

Housing cover50includes a fitting portion51, and a casing member of pump P includes a fitting portion201. The fitting portions51and201are engaged with each other to align the rotation axis Lp of pump P with the rotation axis Lm of motor100. In this example, the fitting portion201is depressed upward, and the fitting portion51is projected upward and fit in the fitting portion201, as shown inFIG. 13. The rotating shaft of pump P and the output shaft of motor100are thus aligned and connected drivingly end to end with each other through the holes of the fitting portions51and201.

Housing cover50includes a first (pump side) cover portion52located between the pump P and motor100, and a second (outer) cover portion53extending radially outwards from the first cover portion52beyond the circumference of pump P. The height of second cover portion53in the z axis direction or vertical direction is greater than the height of first cover portion52, as shown inFIG. 13. Therefore, second cover portion53can cover taller components mounted on the upper side of control system board300. The axial or vertical dimension of the whole system can be reduced by mounting shorter components on the first board portion301of control system board300under the first cover portion51, and mounting taller components on the second board portion302of control system board300under the second cover portion52.

In the second embodiment, the reversible pump P having two outlet ports210and220is driven in the forward and reverse direction by the motor control section1. By using the motor control section1arranged compactly as in the first embodiment, the power steering system is made compact and simple.

FIG. 14shows a variation (or a second practical example) of the second embodiment. The hydraulic power steering system shown inFIG. 14is different from the power steering system ofFIG. 7in the following points. A one-direction pump P′ is employed in place of reversible pump P. A control valve240is provided between pump P′ and the hydraulic cylinder40, and arranged to change over the suck/discharge of the hydraulic fluid to produce the steering assist force in the desired directions. The power steering system ofFIG. 14can provide advantageous effects as in the system ofFIG. 7.

FIGS. 15˜17show a motor control apparatus in a first practical example according to a third embodiment of the present invention. In the third embodiment, the motor control apparatus includes a motor control section1, and an actuating section which is combined with the motor control section to form a hydraulic brake control system. In the third embodiment, the motor control section1is substantially identical to that of the first embodiment, and the actuating section includes a brake control unit500.

FIG. 15shows a vehicle equipped with the brake control system according to the third embodiment. The brake control system shown inFIG. 15is a brake-by-wire system. In this example, the brake system include hydraulic brake actuators65for front wheels FR and FL, and electric brake actuators67for braking rear wheels RR and RL electrically without using the hydraulic pressure. However, the present invention is not limited to this brake system. For example, it is optional to employ hydraulic brake actuators for all the four wheels.

The brake control unit500includes a pump P′ for supplying the hydraulic pressure to hydraulic brake actuators65for braking the front wheels, and solenoid valves510,520and530for controlling the hydraulic pressure supplied from pump P′. This brake control unit500is connected with the motor control section1identical to the motor control section according to the first and second embodiments.

In the third embodiment, a microcomputer330is mounted on the control system board300(as shown inFIGS. 16 and 17). Microcomputer330is configured to control inverters410in accordance with a brake pedal condition or a wheel slip condition. In this example, microcomputer330serves as a main ECU331for fluid pressure calculation and solenoid valve control, and a brake ECU332. However, it is optional to employ two or more microcomputers for main ECU331and brake ECU332. Inverters410are mounted in the same manner as in the first embodiment (as shown inFIG. 6).

A master cylinder61is provided with a stroke sensor62and a stroke simulator63. When a brake pedal64is depressed by a driver, the master cylinder61produces a fluid pressure, and the stroke sensor62sends a stroke signal representing the stroke or depression degree of brake pedal64, to main ECU331. The master cylinder pressure produced by master cylinder61is supplied through oil passages71and72, to brake control unit500, and the fluid pressure controlled by brake control unit500is supplied through oil passages73and74, to the front wheel cylinders (or actuators)65.

Main ECU331calculates a desired front wheel fluid pressure in accordance with the stroke signal, taking account of a vehicle operating condition or vehicle motion variable such as a vehicle speed and a vehicle yaw rate; controls the fluid pressures of the wheel cylinders65by sending a command signal through brake ECU332, to brake control unit500; and acts to brake the front wheels with a regenerative brake unit68on braking. The rear wheel brake actuators66control the braking forces of respective electric calipers67in response to command signals from main ECU331.

Brake control unit500includes pump P′ and solenoid valves510˜530. In the case of a normal brake operation of the brake-by-wire system, brake control unit500shuts off the connection between master cylinder61and wheel cylinders65, and supplies the fluid pressures to wheel cylinders65with pump P′ (shown inFIGS. 16 and 17) to produce the braking force. If a wheel locking tendency is increased by an abrupt braking operation of the driver, the brake control unit500drives solenoid valves510˜530to decrease the wheel locking tendency, and shuts off the supply of the fluid pressure from master cylinder61to the front wheel cylinders65.

Thus, brake control unit500drives the solenoid valves510˜530in the unit appropriately and thereby decreases the brake fluid pressures in front wheel cylinders65to produce the braking force while preventing wheel locking. When the brake-by-wire system is unable to function properly, the brake control unit500produces the braking force by allowing the supply of the master cylinder pressure to wheel cylinders65.

The motor control section1and the brake control unit500are united into a single unit as shown in a x-z plane partial sectional view ofFIG. 16, and an entire sectional view ofFIG. 17. Motor control section1is identical to that of the first and second embodiments.

Motor control section1is joined with brake control unit500in place of gear housing11of the first embodiment, in a flat joint plane C-C. Brake control unit500includes hydraulic pump P′, and is joined, through a housing cover50′, with the housing composed of the motor housing12and power system board housing13.

Pump P′ of this example is of an external gear type, and is driven by the motor100. However, it is optional to employ a pump of any other type. The solenoid valves510˜530for regulating the brake fluid pressure are provided on the x axis positive side of pump P′ (on the right side of pump p′ inFIGS. 16 and 17).

Solenoid valves510˜530includes connection terminals511˜531, and these solenoid valves510˜530are mounted so that the terminals511˜531confront the control system board300of motor control section1. Terminals511˜531projects to control system board300in the z axis negative direction, and are connected with the control circuit on control system board300. Brake control ECU332of microcomputer330mounted on control system board300is configured to control the brake fluid pressure by controlling the open/close states of the solenoid valves310˜330in accordance with a command signal from main ECU331.

In the third embodiment, too, housing cover50′ is placed between pump P′ and the housing composed of motor housing12and power system board housing13, and arranged to close the opening defined by the z axis positive side ends12cand13cof the housings12and13. Housing cover50′ includes a fitting portion which is fit in a recessed portion of a housing501of brake control unit500, and which is shaped to fittingly receive pump P′. Therefore, the fitting portion of housing cover50′ makes it easy to determine the positions of pump P′ and motor100, and to align the motor rotation axis Lm of motor100and the pump rotation axis Lp of pump P′.

By the combination of motor control section1and brake control unit500including pump P′ and solenoid valves510˜530, the third embodiment can provide the same advantageous effects as in the first and second embodiments.

FIG. 18shows a second practical example according to the third embodiment. In the second practical example, pump P′ is received in a recess formed in the brake control unit housing501, and covered with a cover502located on the z axis positive side of the housing501.

FIG. 19shows a third practical example according to the third embodiment. In the third practical example, there is provided a second control system board300bin addition to the first control system board300(or300a). The first control system board300is substantially identical to that of the first practical example shown inFIGS. 16 and 17. In this example, the first and second control system boards300and300bare substantially parallel to each other, and both boards300and300bare connected by a connecting member300cextending along the z axis. The first control system board300on the z axis negative side is enclosed by motor housing12, power system board housing13and housing cover50′. Second control system board300bon the z axis positive side is enclosed by brake system unit housing501and cover503. Solenoid valves510˜533are placed between the first and second control system boards300and300b. The connection terminals511,521and531of first, second and third solenoid valves510,520and530projects in the z axis positive direction toward second control system board300b, and these terminals511,521and531are connected with second control system board300b. In the first practical example shown inFIGS. 16 and 17, the connection terminals511,521and531of first, second and third solenoid valves510,520and530projects in the z axis negative direction toward the control system board300, and these terminals511,521and531are connected with the control system board300.

FIG. 20shows a fourth practical example according to the third embodiment. The fourth practical example employs the first and second control system boards300and300bas in the third practical example, and further employs a pump cover502. Pump cover502is enclosed in cover503, and fixed to the unit housing501so that pump P′ is enclosed liquid-tightly. In the fourth practical example ofFIG. 20, there is provided, between cover50′ and the housing composed of motor housing12and power system board housing13, a cover50similar to the cover50shown inFIG. 13.

FIG. 21shows a fifth practical example according to the third embodiment. The fifth practical example employs a motor front cover140which serves both as a pump cover and a motor cover for motor100. These second through fifth practical examples can provide the same effects as in the first practical example of the third embodiment. In the third embodiment, the solenoid valves can be mounted on the control system board.

This application is based on a prior Japanese Patent Application No. 2004-336806 filed on Nov. 22, 2004, and a prior Japanese Patent Application No. 2005-260111 filed on Sep. 8, 2005. The entire contents of Japanese Patent Application No. 2004-336806 and Japanese Patent Application No. 2005-260111 are hereby incorporated by reference.