JP2013184527A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality electric power steering device with improved productivity and reliability.SOLUTION: A rotary shaft 27 is housed in a gear housing 22 as a housing, first and second housings 30, 31 and a motor housing 24, and is supported via corresponding bearings 42, 43, 44. In an ECU housing section 40, a power board 28 and a control board 29 constituting a part of an ECU 12 is housed and held. On the power board 28, at least a part of a power circuit for driving a brushless motor 18 is mounted. The power board 28 comprises a multilayer aluminum board, for example, with a circuit mounted on one face, and is arranged in surface contact with the inner wall surface of a wall section 34 of a radially thick wall part of the second housing 31 so as to be thermally conductive. The wall section 34 of the second housing 31 functions as a heat sink. The outer wall surface of the wall section 34 abuts on the gear housing 22.

Description

  The present invention relates to an electric power steering apparatus.

  Conventionally, there is an electric power steering device (EPS) that combines an electric motor and a control device that controls driving of the electric motor. As such an electric power steering device, there has been proposed a device in which a control device is integrated with an electric motor and is reduced in size and weight (for example, see Patent Document 1). This electric power steering device is disposed between the electric motor and the speed reduction mechanism in the axial direction of the electric motor, a speed reduction mechanism as a transmission mechanism that decelerates and transmits the rotation of the electric motor to the steering device. It is comprised with the control apparatus with which the circuit board was assembled | attached.

Japanese Patent Laid-Open No. 2002-120739

  However, in the above electric power steering device, when the control device is arranged in the gear housing of the speed reduction mechanism, it is necessary to connect the motor portion and the gear portion to support the shaft of the electric motor when shipping and inspecting the product. In the performance evaluation that has been performed integrally with the electric motor and the control device in the conventional inspection process, for example, the high and low temperature tests, the gear housing may have a large heat mass, so that the accurate temperature characteristic inspection of the motor may not be performed. In addition, since the gear housing is attached in the assembly process of the electric motor and the control device, the manufacturing / inspection equipment may be enlarged and the workability of the assembly / inspection may be reduced.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric power steering device that is of high quality and excellent in productivity and reliability.

  In order to solve the above-mentioned problems, an invention according to claim 1 is directed to an electric motor, a control device that is assembled integrally with the electric motor and controls driving of the electric motor, and the power of the electric motor is used as a steering mechanism. A transmission mechanism for transmitting, and a holding member for holding the control device between the transmission mechanism and the electric motor, wherein the holding member includes the electric motor and the control held by the holding member. The gist of the invention is that a plurality of fastening holes for fixing the device are provided.

  According to the above configuration, in the electric power steering apparatus in which the electric motor and the control device are integrally assembled, the electrical components that constitute the control device that is integrally assembled with the electric motor include the housing of the transmission mechanism and the electric motor. It is hold | maintained at the holding member arrange | positioned between. The holding member is provided with a plurality of fastening holes in the axial direction of the electric motor, and the electric motor and the control device are fixed by bolts. As a result, the performance of the product at the time of shipment can be evaluated with the electric motor and the control device integrated with no transmission mechanism attached, so that the equipment does not increase in size, and dedicated jigs and measurement man-hours are reduced. Can be reduced. In addition, by disposing the electrical components of the control device in the housing of the transmission mechanism without requiring a dedicated heat sink, the motor shaft length can be shortened, and the mountability to the vehicle is improved.

  According to a second aspect of the present invention, in the electric power steering apparatus according to the first aspect, the holding member includes a wall portion that abuts the holding member on the housing of the transmission mechanism, and has the same circle as the fastening hole. The gist is that a plurality of through holes for fastening to the housing of the transmission mechanism are provided on the circumference. According to the above-described configuration, the holding member has a plurality of outer wall surfaces on the transmission mechanism side of the holding member that are in contact with the housing of the transmission mechanism and are provided on the same circumference as the fastening holes in the axial direction of the holding member by bolts. It is fastened and fixed to the housing of the transmission mechanism through the through hole. Accordingly, the electric motor and the control device can be inspected integrally without attaching a transmission mechanism, so that the working time can be reduced, the size in the radial direction can be reduced, and the mounting property to the vehicle is improved.

  According to the present invention, it is possible to provide an electric power steering device with high quality and excellent productivity and reliability.

1 is a schematic diagram showing a schematic configuration of an electric power steering apparatus according to an embodiment of the present invention. 1 is an axial longitudinal sectional view showing a schematic configuration of an electric power steering apparatus according to an embodiment of the present invention. The top view which looked at the housing of the electric motor in FIG. 2 from the arrow A direction. The top view which looked at the gear housing in FIG. 2 from the arrow A direction. The axial direction longitudinal cross-sectional view which shows schematic structure of the electric power steering apparatus by other embodiment of this invention.

Hereinafter, an embodiment in which the present invention is embodied in an electric power steering apparatus will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of an electric power steering apparatus 1 as a vehicle steering apparatus according to an embodiment of the present invention. As shown in FIG. 1, the electric power steering apparatus 1 includes a steering wheel 2 as a steering member, a steering mechanism 4 that steers the steered wheels 3 in conjunction with the rotation of the steering wheel 2, and steering of the driver. And a steering assist mechanism 5 for assisting. The steering wheel 2 and the steering mechanism 4 are mechanically coupled via a steering shaft 6 and an intermediate shaft 7. The intermediate shaft 7 connects the steering shaft 6 and the steering mechanism 4.

  In the present embodiment, a column assist type electric power steering device 1 in which the steering assist mechanism 5 applies assist force (steering assist force) to the steering shaft 6 will be described as an example. The steering shaft 6 extends linearly. Steering shaft 6 includes an input shaft 8 connected to steering wheel 2 and an output shaft 9 connected to intermediate shaft 7. The input shaft 8 and the output shaft 9 are connected via a torsion bar 10 so as to be relatively rotatable on the same axis. That is, when a steering torque greater than a certain value is input to the steering wheel 2, the input shaft 8 and the output shaft 9 rotate in the same direction while rotating relative to each other.

  A torque sensor 11 disposed around the steering shaft 6 detects the steering torque input to the steering wheel 2 based on the relative rotational displacement amounts of the input shaft 8 and the output shaft 9. The torque detection result of the torque sensor 11 is input to an ECU (control device) 12 as a control device. Further, the vehicle speed detection result from the vehicle speed sensor 23 is input to the ECU 12.

  The steered mechanism 4 includes a rack and pinion mechanism including a pinion shaft 13 and a rack shaft 14 as a steered shaft. A steered wheel 3 is connected to each end of the rack shaft 14 via a tie rod 15 and a knuckle arm (not shown). The pinion shaft 13 is connected to the intermediate shaft 7. The pinion shaft 13 rotates in conjunction with the steering of the steering wheel 2. A pinion 16 is connected to the tip of the pinion shaft 13 (the lower end in FIG. 1).

  The rack shaft 14 extends linearly along the left-right direction of the vehicle. A rack 17 that meshes with the pinion 16 is formed in the middle of the rack shaft 14 in the axial direction. By the pinion 16 and the rack 17, the rotation of the pinion shaft 13 is converted into the axial movement of the rack shaft 14. The steered wheel 3 can be steered by moving the rack shaft 14 in the axial direction.

  When the steering wheel 2 is steered (rotated), this rotation is transmitted to the pinion shaft 13 via the steering shaft 6 and the intermediate shaft 7. The rotation of the pinion shaft 13 is converted into an axial movement of the rack shaft 14 by the pinion 16 and the rack 17. Thereby, the steered wheel 3 is steered. The steering assist mechanism 5 includes an electric motor 18 for assisting steering, and a speed reduction mechanism 19 as a transmission mechanism for transmitting the output torque of the electric motor 18 to the steering mechanism 4. In the present embodiment, the speed reduction mechanism 19 is included. A worm gear mechanism is used. That is, the speed reduction mechanism 19 includes a worm shaft 20 as a drive gear (drive-side member of the transmission mechanism) and a worm wheel 21 as a driven gear (driven-side member of the transmission mechanism) that meshes with the worm shaft 20. It is accommodated in a gear housing 22 as a housing. Note that a brushless motor having a three-phase winding is used for the electric motor (hereinafter referred to as a brushless motor) 18 shown in FIG.

  The worm shaft 20 is rotationally driven by the brushless motor 18. The worm wheel 21 is connected to the steering shaft 6 so as to be able to rotate together. The worm wheel 21 is rotationally driven by the worm shaft 20. When the brushless motor 18 rotationally drives the worm shaft 20, the worm wheel 21 is rotationally driven by the worm shaft 20, and the worm wheel 21 and the steering shaft 6 rotate together. The rotation of the steering shaft 6 is transmitted to the pinion shaft 13 via the intermediate shaft 7. The rotation of the pinion shaft 13 is converted into the axial movement of the rack shaft 14. Thereby, the steered wheel 3 is steered. That is, the wheel 3 is steered by rotationally driving the worm shaft 20 by the brushless motor 18.

  The brushless motor 18 is controlled by the ECU 12. The ECU 12 controls the motor 18 based on the torque detection result from the torque sensor 11, the vehicle speed detection result from the vehicle speed sensor 23, and the like. Specifically, the ECU 12 determines a target assist amount using a map in which the relationship between the torque and the target assist amount is stored for each vehicle speed, and controls the assist force generated by the brushless motor 18 to approach the target assist amount. To do.

  Next, FIG. 2 is an axial longitudinal sectional view showing a schematic configuration of the electric power steering apparatus according to one embodiment of the present invention.

  The brushless motor 18 includes a motor housing 24, a rotor 25 and a stator 26 accommodated in the motor housing 24. The rotor 25 includes an annular rotor core 36 attached to the outer periphery of the rotary shaft 27 so as to be able to rotate along with the rotor shaft 36, and a rotor magnet 38 made of, for example, an annular permanent magnet attached to the outer periphery of the rotor core 36 so as to be able to rotate together. Yes. A plurality of magnetic poles are arranged in the circumferential direction on the rotor magnet 38. These magnetic poles are configured so that the N pole and the S pole are alternately switched in the circumferential direction of the rotor 25.

  The stator 26 is fixed to the inner periphery of the motor housing 24. The stator 26 includes a stator core 37 fixed to the inner periphery of the motor housing 24 and a plurality of coils 35. The stator core 37 includes an annular yoke (not shown) of the stator core 37 and a plurality of teeth (not shown) protruding radially inward from the inner periphery of the yoke. Each coil 35 is wound around a corresponding tooth.

  The coil 35 wound around each tooth is connected to a bus bar (not shown). The bus bar is a conductive connecting material used for a connection portion between each coil 35 and the current application line, and functions as a power distribution member for distributing power from a power supply source (not shown) to each coil 35.

  In addition, an ECU housing portion 40 for housing the ECU 12 is formed in the gear housing 22 by the first housing 30 and the second housing 31 that extend upward in the axial direction. The rotating shaft 27 is rotatably supported by a bearing 42 held by the motor housing 24 and a bearing 43 held by the first housing 30. The bearings 42 and 43 are both constituted by known seal bearings.

  The rotation angle sensor 39 for detecting the rotation position of the rotor 25 is arranged in an ECU housing portion 40 provided in the center of the first housing 30 as in the present embodiment. The rotation angle sensor 39 has a stator fixed to the second housing 31 and a rotor attached so as to be able to rotate along with the rotation shaft 27. For example, a resolver can be used as the rotation angle sensor 39. A Hall element can also be used.

  With the above configuration, the rotary shaft 27 is accommodated in the gear housing 22 as the housing, the first and second housings 30 and 31, and the motor housing 24, and is supported via the corresponding bearings 42, 43, and 44. Yes.

  A power board 28 and a control board 29 that constitute a part of the ECU 12 are housed and held in the ECU housing part 40. On the power board 28, at least a part of a power circuit (for example, a switching element such as an FET) for driving the brushless motor 18 is mounted. The power board 28 is made of, for example, a multi-layer board made of an aluminum plate with a circuit mounted on one side, and is disposed in surface contact with the inner wall surface of the wall part 34 of the radially thick part of the second housing 31 so as to be capable of conducting heat. Has been. Here, the wall portion 34 of the second housing 31 functions as a heat sink. Further, the outer wall surface of the wall portion 34 is in contact with the gear housing 22. The bus bar connected to each coil 35 is connected to the power board 28 via a bus bar terminal, for example, by screwing.

  A control circuit for controlling the power circuit is mounted on the control board 29. The control circuit includes a driver that controls each FET of the power circuit and a CPU (microcomputer) that controls the driver. The control board 29 is arranged with a sufficient height between the control board 29 and the power board 28 in the axial direction around the rotation shaft 27, and the control board 29 has an insertion hole 41 through which the rotation shaft 27 is inserted. Is formed through. A rotation angle sensor 39 is connected to the control board 29 via a bus bar terminal.

3 is a plan view of the motor housing 24 and the first and second housings 30 and 31 in FIG. 2 as viewed from the direction of the arrow A, and FIG. 4 is a plan view of the same gear housing 22 as viewed from the direction of the arrow A. FIG.
As shown in FIGS. 3 and 4, the motor housing 24 includes a plurality of (for example, three in the present embodiment) flanges protruding outward in the radial direction of the motor housing 24 and provided at equal intervals in the circumferential direction. It is fastened to a screw hole (fastening hole) 32 of the second housing 31 by a bolt 49 via a common through hole 48 provided in one housing 30. In addition to the fastening holes 32, the second housing 31 has a plurality of (for example, three in this embodiment) provided in the second housing 31 on the same circumference alternately with the fastening holes 32 at equal intervals. The bolt 50 is fastened and fixed to the screw hole 47 of the gear housing 22 through the through hole 33. Further, an insertion hole 46 through which the rotation shaft 27 is inserted is provided in the center of the second housing 31 in the axial direction.

FIG. 5 is an axial longitudinal sectional view showing a schematic configuration of an electric power steering apparatus 1 according to another embodiment of the present invention.
As shown in FIG. 5, the second housing 31 is provided with a wall portion 34 projecting from a slope, and its outer wall surface is in close contact with the gear housing 22, and the inner wall surface is placed in contact with the back surface of the power board 28. Is done. Thereby, the electrical component of ECU12 can be brought closer to the gear housing 22 side.

  Next, operations and effects of the electric power steering apparatus 1 according to the embodiment of the present invention configured as described above will be described.

  According to the above configuration, in the electric power steering apparatus 1 in which the brushless motor 18 and the ECU 12 are integrally assembled, the ECU 12 integrally assembled with the brushless motor 18 is disposed between the gear housing 22 and the brushless motor 18. It arrange | positions in the 1st, 2nd housing 30 and 31 provided. The electrical components that make up the ECU 12 are held in the second housing 31. The second housing 31 is provided with a plurality of (three in this embodiment) screw holes (fastening holes) 32 in the axial direction of the brushless motor 18, and the brushless motor 18 and the ECU 12 are fixed by bolts 49. . Further, the second housing 31 has the wall 34 of the second housing 31 in contact with the gear housing 22 via the motor housing 24 and the first housing 30, and the shaft of the second housing 31 is connected by the bolt 50. It is fastened and fixed to the screw hole 47 of the gear housing 22 through a plurality of (for example, three in this embodiment) through holes 33 provided alternately with the screw holes 32 on the same circumference as the screw holes 32 in the direction. ing.

  As a result, the brushless motor 18 and the ECU 12 are integrally configured, and in this state, for example, a performance evaluation test of temperature characteristics can be performed, so that a dedicated jig and measurement man-hours can be reduced without increasing the size of the equipment. Can do. In addition, a dedicated heat sink for dissipating the power board 28 of the ECU 12 is not necessary, and the motor shaft length can be shortened by arranging the electrical components in the gear housing 22. Furthermore, it is possible to reduce the size in the radial direction, and the mounting property to the vehicle is improved.

  As described above, according to the present embodiment, it is possible to provide an electric power steering device that is high in quality and excellent in productivity and reliability.

  Although one embodiment according to the present invention has been described above, the present invention can also be implemented in other forms.

  In the above-described embodiment, an example in which three insertion holes and screw holes are alternately provided on the same circumference for fixing the housings 24, 31, 31, and 22 has been described. The number of screws that can secure the performance is sufficient.

  In the above-described embodiment, an example in which the present invention is applied to a column assist type electric power steering device has been described. However, a pinion assist type in which the steering assist mechanism 5 applies an assist force to the pinion shaft 13, or the steering assist mechanism 5. Can be applied to a rack assist type having a structure in which an assist force is applied to the rack shaft 14.

  Moreover, in the said embodiment, although the case where the brushless motor 18 and ECU12 were applied to the electric power steering apparatus 1 was shown, it is not limited to this, Other apparatuses (for example, the same brushless motor 18 (for example, The present invention may be applied to an electric oil pump device or the like. Furthermore, although the example which uses the brushless motor 18 as an electric motor was demonstrated, not only this but another motor may be used.

1: electric power steering device, 2: steering wheel, 3: steered wheel, 4: steered mechanism, 5: steering assist mechanism, 6: steering shaft, 7: intermediate shaft, 8: input shaft, 9: output shaft, 10 : Torsion bar, 11: Torque sensor, 12: ECU (control device), 13: Pinion shaft, 14: Rack shaft :, 15: Tie rod, 16: Pinion, 17: Rack,
18: Brushless motor (electric motor), 19: Deceleration mechanism (transmission mechanism), 20: Worm shaft, 21: Worm wheel, 22: Gear housing, 23: Vehicle speed sensor, 24: Motor housing, 25: Rotor, 26: Stator 27: rotating shaft, 28: power board, 29: control board, 30, 31: first and second housings, 32: screw holes (fastening holes), 33: through holes, 34: second housing walls, 35: Coil, 36: Rotor core, 37: Stator core, 38: Rotor magnet, 39: Rotation angle sensor, 40: ECU housing part, 41: Control board insertion hole, 42, 43, 44, 45: Bearing, 46: Second Housing insertion hole, 47: Gear housing screw hole, 48: Insertion hole, 49.50: Bolt

Claims (2)

An electric motor;
A control device integrated with the electric motor for driving and controlling the electric motor; a transmission mechanism for transmitting power of the electric motor to a steering mechanism; and the control device between the transmission mechanism and the electric motor. A holding member for holding, and the holding member is provided with a plurality of fastening holes for fixing the electric motor and the control device held by the holding member. Power steering device. The electric power steering apparatus according to claim 1, wherein
The holding member includes a wall portion that abuts the holding member on the housing of the transmission mechanism, and is provided with a plurality of through holes for fastening the holding member to the housing of the transmission mechanism on the same circumference as the fastening hole. An electric power steering device characterized by that.

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