JP2011079495A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device improving its reliability, by preventing generation of noise by vibration of a control device. <P>SOLUTION: An ECU 22 is supported by a motor housing 36 by inserting a bolt 51 into through-holes 47 and 48 respectively formed in a casing 45 and the motor housing 36 of the ECU 22. An elastic support member 61 including a collar 62 for inserting the bolt 51 and an elastic body 63 arranged on an outer peripheral surface of the collar 62, is arranged between the casing 45, the bolt 51 and the motor housing 36, so that the ECU 22 is elastically supported by the motor housing 36 via the elastic support member 61. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric power steering device in which a control device for controlling the operation of a motor is disposed in the vicinity of a motor that applies assist force to a steering system.

  2. Description of the Related Art Conventionally, power steering apparatuses for vehicles include an electric power steering apparatus (EPS) using a motor as a drive source. As such an EPS, there is one in which a control device for controlling the operation of a motor is fixed to a motor housing and the motor and the control device are integrated in order to improve the mountability on a vehicle. (For example, patent document 1).

  Incidentally, since the motor vibrates due to its operation, when the control device is supported with respect to the motor housing as in Patent Document 1, the control device may vibrate greatly due to resonance with the motor. If the control device vibrates greatly in this way, noise may be generated or a circuit element or the like inside the control device may be adversely affected. Therefore, EPS is known in which an elastic member such as rubber is interposed between the control device and the motor, thereby suppressing the control device from greatly vibrating and preventing generation of noise (Patent Document). 2).

Japanese Patent Laid-Open No. 10-86831 JP 2007-145154 A

  However, in the configuration described in Patent Document 2, the casing of the control device is directly fixed to the motor housing by a shaft-like fastening member such as a bolt, that is, the control device is rigidly supported by the motor housing. Therefore, the vibration of the motor is directly transmitted to the control device via the fastening member. Therefore, even if the elastic member restrains the control device from resonating with the motor and greatly vibrates, the vibration of the motor continues to be directly transmitted to the control device, which adversely affects circuit elements and the like inside the control device. This cannot be surely prevented, and there is still room for improvement in terms of the reliability of the control device.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an electric power steering apparatus capable of preventing the generation of noise due to vibration of the control apparatus and improving the reliability thereof. It is to provide.

  In order to achieve the above object, an invention according to claim 1 is directed to a motor for applying an assist force for assisting a steering operation to a steering system, and a control device for controlling the operation of the motor by supplying driving power to the motor. In the electric power steering apparatus comprising: the control device, the shaft-shaped fastening member is inserted into through holes respectively formed in the motor housing of the motor and the casing of the control device, so that the motor housing An elastic support member is provided between the casing and the fastening member and the motor housing, and the elastic support member includes a collar through which the fastening member is inserted and an outer peripheral surface of the collar. The control device is connected to the motor housing via the elastic support member. And summarized in that it is elastically supported Te.

  According to the above configuration, since the elastic support member is interposed between the casing and the fastening member and the motor housing, and the control device is elastically supported with respect to the motor housing, vibrations transmitted from the motor to the control device are prevented. Absorbed by elastic body. In this way, the vibration itself transmitted to the control device by the elastic body is suppressed, so that unlike the conventional case where the control device is rigidly supported by the motor housing, the vibration of the motor is a fastening member. It is prevented from being transmitted directly to the control device via the. Therefore, it is possible to prevent the generation of noise by suppressing the vibration of the control device, and to reliably prevent adverse effects on circuit elements and the like inside the control device, thereby improving the reliability.

  The invention according to claim 2 is characterized in that, in the electric power steering apparatus according to claim 1, one end of the fastening member is fixed to a rigid portion provided in a vehicle other than the motor housing.

  As vibration transmitted to the control device, in addition to motor vibration, there is also vibration generated by running the vehicle, for example. Therefore, such vibration is generated only by elastically supporting the control device with respect to the motor housing. As a result, the attitude of the control device may become unstable. In this regard, according to the above configuration, since one end of the fastening member is fixed to a rigid portion provided in the vehicle other than the motor housing, for example, even if vibration generated by traveling of the vehicle is transmitted to the control device, the control device Can stabilize the posture. Further, since heat generated by supplying current to the circuit elements inside the control device is transmitted to the rigid portion of the vehicle via the fastening member, the heat dissipation of the control device can be improved.

  According to a third aspect of the present invention, in the electric power steering apparatus according to the second aspect of the present invention, the electric power steering device includes a reduction mechanism that meshes a worm wheel coupled to a steering shaft and a worm gear coupled to the motor, The rotation of the motor is decelerated by the speed reduction mechanism and transmitted to the steering system. The motor housing has an extension portion, and the extension portion extends in a direction perpendicular to the axial direction of the motor. The control device is disposed on one side in the axial direction of the motor in the extension portion, and the gear housing that houses the worm gear is on the other side in the axial direction of the motor in the motor housing. And a wheel housing that accommodates the worm wheel sandwiches the extension portion with the control device. It is intended to be fixed to the gear housing so as to counter the rigid portion to which one end of the fastening member is fixed, and summarized in that a said wheel housing.

  According to the above configuration, one end of the fastening member is fixed to the wheel housing. Here, the worm wheel is connected to the motor via a worm gear, and the wheel housing that houses the worm wheel is provided at a position relatively away from the motor. Therefore, heat and vibration generated by the motor are less likely to be transmitted to the wheel housing as compared to, for example, a gear housing that houses a worm gear. For this reason, for example, compared with the case where one end of the fastening member is fixed to the gear housing, the heat generated by the control device can be efficiently radiated and vibration transmitted to the control device via the fastening member can be reduced. be able to.

  In the above configuration, the control device is arranged on one side of the extending portion in the axial direction of the motor, that is, the control device is on one side of the axial direction of the motor and orthogonal to the axial direction of the motor. Placed in. The wheel housing is fixed to the gear housing so as to face the control device with the extending portion interposed therebetween.

  Here, the worm wheel is disposed in a direction perpendicular to the axial direction of the worm gear, and the wheel housing is disposed in a direction orthogonal to the axial direction of the gear housing. That is, the wheel housing is disposed on the other side in the axial direction with respect to the motor and in a direction orthogonal to the axial direction of the motor. Therefore, when the control device is disposed on one side in the axial direction of the motor in the extending portion, the member disposed on the other side in the axial direction of the motor in the control device is a member disposed at the closest position to the wheel housing. It becomes. Therefore, by fixing the wheel housing to the gear housing so as to face the extending portion and fixing the fastening member to the wheel housing, it is possible to suppress an increase in the axial length of the fastening member.

  According to the present invention, it is possible to provide an electric power steering apparatus capable of preventing the generation of noise due to vibration of the control apparatus and improving the reliability thereof.

The schematic block diagram of an electric power steering device (EPS). The partial sectional view which looked at the support structure with respect to the motor of a control apparatus from the axial direction of the steering shaft. The partial cross section figure which looked at the support structure to the motor of a control device from the control device side. Sectional drawing of an elastic support member. The partial cross section figure which looked at the support structure with respect to the motor of another control apparatus from the axial direction of the steering shaft.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1, in an electric power steering apparatus (hereinafter referred to as “EPS”) 1, a steering shaft 3 to which a steering 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4. The rotation of the steering shaft 3 accompanying the steering operation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4. The steering shaft 3 is formed by connecting a column shaft 8, an intermediate shaft 9, and a pinion shaft 10. Then, the reciprocating linear motion of the rack shaft 5 accompanying the rotation of the steering shaft 3 is transmitted to a knuckle (not shown) via tie rods 11 connected to both ends of the rack shaft 5, so that the steering angle of the steered wheels 12 is increased. That is, the traveling direction of the vehicle is changed.

  The EPS 1 also includes an EPS actuator 21 that applies an assist force for assisting the steering operation to the steering system, and an ECU 22 as a control device that controls the operation of the EPS actuator 21.

  The EPS actuator 21 is a so-called column type EPS actuator, and a motor 23 as a driving source thereof is drivingly connected to the column shaft 8 via a speed reduction mechanism 25. Specifically, the speed reduction mechanism 25 is configured by meshing a worm wheel 26 connected to the column shaft 8 and a worm gear 27 connected to the motor 23, and the rotation of the motor 23 is caused by the speed reduction mechanism 25. It is decelerated and transmitted to the column shaft 8. The rotation of the motor 23 is decelerated by the speed reduction mechanism 25 and transmitted to the column shaft 8 so that the motor torque is applied to the steering system as an assist force.

  On the other hand, a vehicle speed sensor 28 and a torque sensor 29 are connected to the ECU 22. Based on the vehicle speed V and steering torque τ detected by these sensors, the ECU 22 controls the assist torque generated by the motor 23 through the operation of the EPS actuator 21, specifically, the supply of drive power to the motor 23. Thus, the control of the assist force applied to the steering system (power assist control) is executed.

Next, the support structure for the motor 23 and the ECU 22 will be described in detail.
As shown in FIG. 2, the motor 23 is supported by a speed reducer housing 31 that houses the speed reduction mechanism 25. Specifically, the reduction gear housing 31 includes a wheel housing 32 that houses the worm wheel 26 and a gear housing 33 that houses the worm gear 27, and is fixed to a vehicle frame (not shown). In the present embodiment, the reduction gear housing 31 is made of an aluminum alloy, and the wheel housing 32 and the gear housing 33 are integrally formed. The motor 23 is fixed with respect to the gear housing 33.

  More specifically, the gear housing 33 is formed in a substantially cylindrical shape, and an annular mounting portion 35 extending radially outward is formed at the upper end in the axial direction. On the other hand, the housing (hereinafter referred to as “motor housing”) 36 of the motor 23 is formed in a substantially cylindrical shape, and an annular attachment portion 37 extending outward in the radial direction is formed at the lower end in the axial direction. In addition, a plurality of bolt holes 38 and 39 are formed in each of the attachment portions 35 and 37, and the motor housing 36 is disposed on the gear housing 33 so that the attachment portion 37 abuts on the attachment portion 35. In this state, the bolt 41 is fixed to the gear housing 33 by being screwed into the bolt holes 38 and 39. In FIG. 2, only one bolt hole 38, 39 and one bolt 41 are shown for convenience of explanation.

  The wheel housing 32 is fixed to the gear housing 33 on one side (left side in FIG. 2) orthogonal to the axial direction. The motor housing 36 is formed with an extending portion 43 that extends from the mounting portion 37 to one side (left side in FIG. 2) orthogonal to the axial direction of the motor 23. The ECU 22 is arranged on one side in the axial direction of the motor 23 (upper side in FIG. 2). That is, the ECU 22 is disposed in a direction orthogonal to the axial direction of the motor 23, the gear housing 33 is fixed to the other side (lower side in FIG. 2) of the motor 23 in the motor housing 36, The wheel housing 32 is fixed to the gear housing 33 so as to face the ECU 22 with the extending portion 43 interposed therebetween.

  As shown in FIGS. 2 and 3, the casing 45 of the ECU 22 is formed in a substantially rectangular parallelepiped shape, and a lower end of the casing 45 extends to both sides of the casing 45 in the short direction (left and right direction in FIG. 3). 46 is formed. Through holes 47 are formed in the fixing portions 46, and through holes 48 are formed in the extending portions 43 at positions corresponding to the through holes 47. Then, the ECU 22 inserts a bolt 51 as a fastening member into the through holes 47 and 48 formed in the casing 45 (fixed portion 46) and the motor housing 36 (extending portion 43), respectively. It is supported.

  The ECU 22 and the motor 23 are electrically connected via a power line 52, and the motor 23 is configured to be supplied with driving power corresponding to the target assist force from the ECU 22 via the power line 52. ing. In addition, circuit elements such as a microcomputer and a switching element (not shown) are provided inside the ECU 22.

  By the way, since the motor 23 vibrates due to its operation, when the ECU 22 is supported by the motor housing 36 as described above, the ECU 22 may vibrate greatly due to resonance with the motor 23.

  Therefore, the EPS 1 of the present embodiment includes an elastic support member 61 provided between the casing 45 and the bolt 51 and the motor housing 36, and the ECU 22 elastically acts on the motor housing 36 via the elastic support member 61. It is configured to be supported.

  More specifically, as shown in FIG. 4, the elastic support member 61 includes a cylindrical collar 62 through which the bolt 51 is inserted, and a cylindrical elastic body 63 provided on the outer peripheral surface of the collar 62. Yes. The collar 62 is made of a rigid material such as metal, and reinforces the rigidity of the elastic support member 61 in the axial direction (tightening direction of the bolt 51). The elastic body 63 of the present embodiment is made of a rubber-based elastic material, and a pair of flange portions 64 extending radially outward are formed at both ends in the axial direction of the elastic body 63. As shown in FIGS. 2 and 3, the elastic support member 61 is inserted into the through hole 48 of the extending portion 43, and the flange portions 64 of the elastic body 63 are disposed on both axial sides of the through hole 48. It is designed to be locked.

  One end (the lower end in FIGS. 2 and 3) of the bolt 51 is fixed to a wheel housing 32 as a rigid portion provided in the vehicle other than the motor housing 36. Specifically, as shown in FIG. 3, the wheel housing 32 is formed with projecting portions 65 projecting on both sides in the short direction of the casing 45, and each projecting portion 65 has the through holes 47, 48. Bolt holes 66 are formed at positions corresponding to

  Then, the ECU 22 is screwed into the bolt hole 66 of the projecting portion 65 via the through hole 47 of the casing 45 (fixed portion 46) and the collar 62 of the elastic support member 61, so that the ECU 22 is attached to the motor housing 36. And is rigidly fixed to the wheel housing 32.

As described above, according to the present embodiment, the following operational effects can be achieved.
(1) The ECU 22 is supported with respect to the motor housing 36 by inserting bolts 51 into through holes 47 and 48 formed in the casing 45 and the motor housing 36 of the ECU 22, respectively. The ECU 22 is provided between the casing 45 and the bolt 51 and the motor housing 36 by providing the collar 62 through which the bolt 51 is inserted and the elastic support member 61 provided on the outer peripheral surface of the collar 62. The motor housing 36 is elastically supported via the elastic support member 61.

  According to the above configuration, the elastic support member 61 is interposed between the casing 45 and the bolt 51 and the motor housing 36, and the ECU 22 is elastically supported with respect to the motor housing 36. The generated vibration is absorbed by the elastic body 63. In this way, since the vibration itself transmitted from the motor 23 to the ECU 22 is suppressed by the elastic body 63, the ECU 22 is rigidly supported by the motor housing 36 as in the past (see Patent Document 2). Unlike this, the vibration of the motor 23 is prevented from being directly transmitted to the ECU 22 via the bolt 51. Therefore, it is possible to prevent the occurrence of noise by suppressing the vibration of the ECU 22, and to reliably prevent adverse effects on circuit elements and the like inside the ECU 22 and improve reliability.

(2) One end of the bolt 51 is fixed to the wheel housing 32 as a rigid portion provided in a vehicle other than the motor housing 36.
Here, as vibration transmitted to the ECU 22, there is vibration generated by, for example, traveling of the vehicle in addition to the vibration of the motor 23, so that the ECU 22 is only supported elastically with respect to the motor housing 36. Such a vibration may cause the posture of the ECU 22 to become unstable. In this regard, according to the above configuration, since one end of the bolt 51 is fixed to the wheel housing 32, the posture of the ECU 22 can be stabilized even when, for example, vibrations generated by traveling of the vehicle are transmitted to the ECU 22. Further, since heat generated by supplying current to the circuit elements inside the ECU 22 is transmitted to the wheel housing 32 via the bolts 51, the heat dissipation of the ECU 22 can be improved.

  (3) The motor housing 36 is formed with an extending portion 43 extending in one direction orthogonal to the axial direction of the motor 23 and having a through hole 48, and the ECU 22 is connected to the extending portion 43 in the axial direction of the motor 23. Placed on the side. Further, the gear housing 33 is fixed to the other side of the motor housing 36 in the axial direction of the motor 23, and the wheel housing 32 is fixed to the gear housing 33 so as to face the ECU 22 with the extending portion 43 interposed therebetween. . Then, one end of the bolt 51 was fixed to the wheel housing 32.

  Here, the worm wheel 26 is connected to the motor 23 via the worm gear 27, and the wheel housing 32 is provided at a position relatively away from the motor 23. Therefore, the heat and vibration generated by the motor 23 are less likely to be transmitted to the wheel housing 32 compared to the gear housing 33, for example. Therefore, for example, compared with the case where one end of the bolt 51 is fixed to the gear housing 33, the heat generated in the ECU 22 can be radiated efficiently, and vibration transmitted to the ECU 22 through the bolt 51 can be reduced. it can.

  In the above configuration, the ECU 22 is disposed on one side in the axial direction of the motor 23 in the extending portion 43, that is, the ECU 22 is on one side in the axial direction with respect to the motor 23 and orthogonal to the axial direction of the motor 23. It is arranged in the direction to do. The wheel housing 32 is fixed to the gear housing 33 so as to face the ECU 22 with the extending portion 43 interposed therebetween.

  Here, the worm wheel 26 is disposed in a direction orthogonal to the axial direction of the worm gear 27, and the wheel housing 32 is disposed in a direction orthogonal to the axial direction of the gear housing 33. is there. That is, the wheel housing 32 is arranged on the other side in the axial direction with respect to the motor 23 and in a direction orthogonal to the axial direction of the motor 23. Therefore, when the ECU 22 is arranged on one side in the axial direction of the motor 23 in the extending portion 43, the wheel housing 32 is arranged at the closest position as a member arranged on the other side in the axial direction of the motor 23 in the ECU 22. It becomes a member. Therefore, by fixing the wheel housing 32 to the gear housing 33 so as to face the extending portion 43 and fixing the bolts 51 to the wheel housing 32, it is possible to suppress an increase in the axial length of the bolts 51.

(4) Since the wheel housing 32 is made of an aluminum alloy having a high thermal conductivity, the heat generated in the ECU 22 can be radiated more efficiently via the bolts 51.
(5) The elastic body 63 is made of a rubber-based elastic material. Here, when the ECU 22 is directly fixed to the motor housing 36 with a bolt such as iron as in the prior art, the heat generated by the motor 23 is easily transmitted to the ECU 22 via the bolt, and the ECU 22 may be overheated. In this regard, according to the above configuration, since the elastic body 63 made of a rubber-based elastic material having a lower thermal conductivity than that of a metal such as iron is interposed between the bolt 51 and the motor housing 36, the motor 23 The generated heat is hardly transmitted to the ECU 22 via the bolt 51, and the ECU 22 can be prevented from overheating.

  (6) A pair of flange portions 64 extending outward in the radial direction are formed at both axial ends of the elastic body 63. According to the above configuration, since the flange portion 64 is engaged with both ends of the through hole 48 of the motor housing 36, the elastic support member 61 is prevented from falling out of the through hole 48, and thus the ease of assembly of the ECU 22 is improved. Can be achieved.

In addition, the said embodiment can also be implemented in the following aspects which changed this suitably.
-In above-mentioned embodiment, although ECU22 was provided in the axial direction one side of the motor 23 in the extension part 43, not only this but the axial direction of the motor 23 in the extension part 43 as shown in FIG. It may be provided on the other side. In this case, the ECU 22 is elastically supported only by the motor housing 36 by, for example, screwing the nut 71 onto the tip of the bolt 51.

  In the above embodiment, one end of the bolt 51 is fixed to the wheel housing 32 as a rigid portion provided in a vehicle other than the motor housing 36. However, the present invention is not limited to this, and the rigidity provided in the vehicle other than the motor housing 36 is used. If it is a part, it may be fixed to another rigid part such as a gear housing 33 or a vehicle frame.

  In the above embodiment, one end of the bolt 51 is fixed to the wheel housing 32. However, the present invention is not limited to this, and by screwing a nut to one end of the bolt 51, the ECU 22 is elastically supported only by the motor housing 36. You may do it.

In the above embodiment, the bolt 51 is used as the shaft-shaped fastening member. However, the present invention is not limited to this, and other fastening members such as rivets may be used.
In the above embodiment, the pair of flange portions 64 extending radially outward are formed at both ends in the axial direction of the elastic body 63. However, the present invention is not limited to this, and the flange portions 64 may not be formed.

In the above embodiment, the speed reducer housing 31 is made of an aluminum alloy, but is not limited thereto, and may be made of other materials such as iron.
In the above embodiment, the elastic body 63 is configured by a rubber-based elastic material. However, the elastic body 63 is not limited thereto, and may be configured by other elastic materials such as a resin material.

In the above embodiment, the present invention is embodied in a column assist type EPS, but may be applied to other types of EPS such as a so-called rack assist type.
Next, technical ideas that can be understood from the above embodiments and other examples will be described below together with their effects.

  (A) The electric power steering apparatus according to claim 3, wherein the wheel housing is made of an aluminum alloy. According to the said structure, since a wheel housing consists of an aluminum alloy with high heat conductivity, the heat | fever generated with the control apparatus via the fastening member can be thermally radiated more efficiently.

  (A) The electric power steering apparatus according to any one of claims 1 to 3 and (A), wherein the elastic body is made of a rubber-based elastic material. When the control device is directly fixed to the motor housing with a fastening bolt such as iron as in the past (see Patent Document 2), the heat generated by the motor is easily transmitted to the ECU via the fastening bolt, and the ECU overheats. There is a fear. In this respect, according to the above configuration, an elastic body made of a rubber-based elastic material having a lower thermal conductivity than a metal such as iron is interposed between the casing and the fastening member and the motor housing, and thus is generated in the motor. It is difficult to transmit the heat to the ECU via the fastening bolt, and the ECU can be prevented from overheating.

  (C) In the electric power steering device according to any one of claims 1 to 3, and (a) and (b) above, a pair of radially extending outer ends is provided at both ends in the axial direction of the elastic body. An electric power steering device characterized in that a flange portion is formed. According to the above configuration, since the flange portion is locked to both ends of the through hole of the motor housing, the elastic body (elastic support member) is prevented from falling out of the through hole. Can be achieved.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device, 3 ... Steering shaft, 8 ... Column shaft, 22 ... ECU, 23 ... Motor, 25 ... Deceleration mechanism, 26 ... Worm wheel, 27 ... Worm gear, 32 ... Wheel housing, 33 ... Gear housing, 36 DESCRIPTION OF SYMBOLS ... Motor housing, 43 ... Extension part, 45 ... Casing, 47, 48 ... Through-hole, 51 ... Bolt, 61 ... Elastic support member, 62 ... Collar, 63 ... Elastic body, 64 ... Flange part, 65 ... Projection part.

Claims (3)

In an electric power steering apparatus comprising: a motor that applies an assist force for assisting a steering operation to a steering system; and a control device that controls the operation of the motor by supplying drive power to the motor.
The control device is supported with respect to the motor housing by inserting a shaft-like fastening member into through holes formed in the motor housing of the motor and the casing of the control device, respectively.
An elastic support member is provided between the casing and the fastening member and the motor housing, and the elastic support member includes a collar through which the fastening member is inserted and an elastic body provided on an outer peripheral surface of the collar,
The electric power steering apparatus, wherein the control device is elastically supported with respect to the motor housing via the elastic support member. The electric power steering apparatus according to claim 1, wherein
One end of the fastening member is fixed to a rigid portion provided in a vehicle other than the motor housing. The electric power steering apparatus according to claim 2,
A speed reduction mechanism comprising a worm wheel connected to a steering shaft and a worm gear connected to the motor, the rotation of the motor being decelerated by the speed reduction mechanism and transmitted to the steering system; ,
An extension portion is formed in the motor housing, and the extension portion extends in a direction orthogonal to the axial direction of the motor and has the through hole.
The control device is disposed on one side in the axial direction of the motor in the extension portion,
The gear housing that houses the worm gear is fixed to the other side of the motor housing in the axial direction of the motor, and the wheel housing that houses the worm wheel faces the control device with the extending portion interposed therebetween. Is fixed to the gear housing,
The electric power steering apparatus according to claim 1, wherein the rigid portion to which one end of the fastening member is fixed is the wheel housing.

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