JP2000053007A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device having a feed part at the depth of a yoke in which a control drive part of it is integrally provided with a device main body without impairing assembling workability. SOLUTION: In an electric power steering device comprising a housing A to contain a rack shaft, and hold a coupling part of the rack shaft with a pinion of a steering shaft, a motor disposed in the housing A, and a ball screw mechanism contained in the housing A to transmit torque of the motor as steering assisting force to the rack shaft, a feed opening part 95 and a second opening part 98 are formed at a part of the housing A facing a feed part 13 of the motor. A driver unit 92 is installed on the housing A by directly putting a heat radiation plate 92a at a bottom part of it to get in contact with the housing A in the condition where it is connected to the feed part 13 through the feed opening part 95. A slide contact part of a commutator with a brush can be visually recognized through the second opening part 98 in the housing A, and a terminal board 92e is spot-welded to a contact plate using this.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering device for a vehicle, and more particularly to a technique effective when applied to an electric power steering device used for a rack and pinion type steering device. is there.

[0002]

2. Description of the Related Art In recent years, many vehicles are equipped with a so-called power steering device for assisting the steering force of the vehicle, and various power steering devices such as a hydraulic type and an electric type have been proposed. Among such power steering devices, an electric power steering device (so-called electric power steering) applied to a rack and pinion type steering device includes:
There is known a rack assist type in which a steering assist force is obtained by an electric motor provided coaxially with a rack shaft.

FIG. 7 is an explanatory diagram showing an example of such a rack assist type power steering device. As shown in FIG. 7, the electric power steering device includes an electric motor 52 provided coaxially with a rack shaft 51, and transmits a steering assist force generated by the electric motor 52 to the rack shaft 51 via a ball screw mechanism 53. . Then, the steered wheels are steered by the steering assist force and the manual steering force, so that the driver's steering burden is reduced.

In this case, the rack shaft 51 is connected at both ends to steered wheels via tie rods or knuckle arms and the like, and is connected to a steering shaft 54 connected to a steering handle or the like by rack and pinion. The driver reciprocates in the left-right direction in FIG. 7 by the steering operation of the driver. The electric motor 52 has a configuration in which a cylindrical armature shaft 56 and a field device 57 are coaxially inserted into a cylindrical yoke 55, and power is supplied from a power supply unit 58. Further, the field device 57 includes a magnet 59 attached to the inner periphery of the yoke 55 and an armature core 60 attached to the outer periphery of the armature shaft 56. The rotational force generated by the electric motor 52 is transmitted as a reciprocating motion in the axial direction to the rack shaft 51 via a ball screw mechanism 53 provided at the left end of the armature shaft 56 in the drawing, thereby assisting the steering force.

[0005] The power supply section 58 is provided with a brush 61 and a commutator 62 slidably contacting the brush 61, through which electric power is supplied to the armature portion of the electric motor 52. In this case, the brush 61 is housed and held in a brush holder 63, and is provided with a commutator 6 by a not-shown elastic machine.
2 is pressed with a predetermined pressing force. Also, brush 6
A terminal plate 65 is spot-welded to one end of one pigtail 64. The terminal plate 65 is connected to the housing 6.
6 and project outside to the outside, where a coupler 67 is attached to form a power supply terminal.

[0006] On the other hand, there has been proposed a power steering device and a control drive unit thereof which are integrated with a control element such as an FET in such a power supply unit. For example, JP-A-6-2
No. 55504 discloses an electric power system in which a hollow chamber is formed at a joint between a housing accommodating a brushless motor and a housing accommodating a handle shaft, and a power circuit unit accommodating an FET and a circuit board is disposed therein. A steering device is shown. Also, JP-A-8-26125
Japanese Patent Application Laid-Open Publication No. H11-163873 discloses an electric steering device in which a FET and a substrate are accommodated in a gear box housing that holds a steering shaft and is connected to a motor yoke.

[0007]

Here, the apparatus shown in FIG. 7 or the above-mentioned publication has a configuration in which a power supply section is provided at a joint between a housing (or yoke) on the electric motor side and a housing on the steering shaft side. Therefore, a control circuit or the like can be relatively easily incorporated between them. That is, since the control circuit and the like can be incorporated in such a manner as to be sandwiched in the vicinity of the division surface, the device main body and the control drive unit can be easily integrated, and there is no problem in the assembly work.

However, even with the same power steering device, a housing and a yoke on the steering shaft side are integrally formed, and a power supply unit, an armature, a field device, and the like are incorporated therein, and this is replaced with another ball screw mechanism. In the case of the type that is connected to the housing, the power supply unit does not come near the divided portion, so that the control drive unit cannot be easily integrated as in the previous example. That is, in this type of power steering device, one end of the yoke portion of the steering shaft side housing is formed in a closed cylindrical shape except for the rack shaft insertion portion, and the power supply portion is disposed at the deepest portion of the closed end. Is done. Therefore, if the control drive unit is to be integrated into the housing, various components must be assembled into the interior of the housing from the opening side, and there is a problem in terms of assembly workability. For this reason, a configuration in which a space for a control section is provided in a part of the housing and a control element and a substrate are incorporated therein cannot be easily adopted as in the above example, and improvement thereof has been desired.

An object of the present invention is to provide a control drive unit integrally with the main body of the electric power steering apparatus of this type without impairing the assembling workability.

[0010]

SUMMARY OF THE INVENTION An electric power steering apparatus according to the present invention includes a rack shaft connected to a steering wheel, a rack tooth movably accommodated in the rack shaft, and a steering handle. A first housing that holds a coupling portion that meshes with a pinion of a steering shaft connected to the motor, and an electric motor that is disposed coaxially around the rack shaft in the first housing and supplies a steering assist force to the rack shaft. And a ball screw mechanism for connecting a nut portion connected to an armature shaft of the motor and a screw portion formed on the rack shaft with a ball member interposed therebetween and transmitting the rotational force of the motor to the rack shaft as steering assisting force. And a second housing accommodating a ball screw mechanism, wherein the inside and outside of the first housing are connected to a portion of the first housing facing a power supply unit of an electric motor. And a control drive unit for controlling and driving the electric motor is provided integrally with the first housing outside the first housing, and the control drive unit is connected to the electric motor through the power supply opening. Is electrically connected to the power supply unit.

Thus, even in the case of an electric power steering device of a type in which the power supply portion is incorporated in the interior of the first housing, the control drive means of the first power drive device can be used without impairing the assembling workability.
It can be provided integrally with the housing. Further, since the control driving means is provided outside the housing at a distance from the power supply section, the control driving means is not adversely affected by the brush abrasion powder.

[0012] In this case, a second opening may be further formed at a portion of the first housing facing the power supply portion of the electric motor so that a sliding contact portion between the commutator and the brush of the electric motor can be visually recognized. It is possible to easily check the sliding state between the brush and the commutator in the power supply unit.

Further, the control driving means is provided with a terminal plate which is inserted into the first housing through the power supply opening and is visible from the second opening, and this terminal plate is electrically connected to the brush of the electric motor. The contact plate and the second opening may be used for welding.

Further, the control driving means is formed by disposing an element for controlling and driving the electric motor on a metal radiating plate, and forming the element in a state in which the radiating plate is in direct contact with the first housing. It may be mounted on the housing,
This makes it possible to enhance the heat radiation of the control driving means.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing a partial cross section of the entire configuration of an electric power steering apparatus according to Embodiment 1 of the present invention.

As shown in FIG. 1, the electric power steering device (hereinafter, abbreviated as a power steering device) includes a hollow electric motor 1 and a rack shaft 2 similar to the conventional power steering device shown in FIG.
, For example, and is attached as a steering device for steering wheels such as front wheels of an automobile. And
The steering assist force generated by the electric motor 1 is transmitted to the rack shaft 2 via the ball screw mechanism 3 to reduce the driver's steering burden.

As shown in FIG. 1, the power steering apparatus has a structure in which a housing A (first housing) and a housing B (second housing) integrated with a yoke 7 of the electric motor 1 are connected. The rack shaft 2 is slidably mounted in the rack shaft 2 in the left-right direction. The wheels are connected to both ends of the rack shaft 2 via tie rods, knuckle arms, and the like in a state where the rack shaft 2 is attached to the vehicle main body by a bracket (not shown) and the mounting hole 10 of the housing B.

On the other hand, the housing A is a hollow member made of aluminum die cast, and a cylindrical motor yoke (hereinafter abbreviated as yoke) 7 is integrally cast into the housing A. Further, a coupling portion 6 between the steering shaft 5 and the rack shaft 2 connected to the steering handle is formed on the right end side of the housing A in FIG. In the connecting portion 6, a pinion (not shown) provided on the steering shaft 5 and a rack tooth (not shown) formed on a side portion of the rack shaft 2 mesh with each other. Is converted to left and right movement. A torque sensor (not shown) for detecting the rotational torque of the steering shaft 5 is provided on the shaft of the connecting portion 6, and the auxiliary steering force of the electric motor 1 is controlled based on the detected value.

Next, the electric motor 1 has a configuration in which a cylindrical armature shaft 11 and a field device 12 are coaxially inserted into a cylindrical yoke 7. Then, the rack shaft 2 is assembled so as to pass through the inside of the armature shaft 11. The field device 12 is composed of a magnet 14 attached to the inner periphery of the yoke 7 and an armature core 15 attached to the outer periphery of the armature shaft 11.
Is supplied with power from the power supply unit 13. Further, the yoke 7 is a cylindrical member made of iron, and is formed to have a substantially constant thickness by a cylindrical pipe.
It is in a state of being cast inside.

A plurality of magnets 14 as field poles constituting the field device 12 are arranged inside the yoke 7 at intervals in the circumferential direction. One end (the right end in FIG. 1) of the armature shaft 11 is held by a bearing 17 attached to the housing A. Also,
A tapered spline is formed on the other end side (the left end in FIG. 1), and the nut portion 1 of the ball screw mechanism 3 is formed.
9 is fitted with a spline similarly formed at the end. Thus, the rotation of the armature shaft 11 is transmitted to the nut 19.

The power supply section 13 is a section for supplying electric power to the armature, and has a configuration including a commutator 22 fixed to the armature shaft 11 and a brush 23 which is an electrical contact with the commutator 22. In the power steering device, a so-called disc-type commutator is used as the commutator 22, and the brush 23 is in sliding contact with the right end face in the axial direction. This is because the present power steering device has a configuration in which the brush 23 is incorporated in the interior of the housing A, and therefore, it is difficult to assemble a brush that slides in a radial direction. On the other hand, the brush 23
Are held in a brush holder 41 made of synthetic resin,
It is pressed against the commutator 22 with a predetermined pressing force by a not-shown bullet. Further, the brush holder 41 is provided with a terminal 91 electrically connected to the brush 23.

Here, in the power steering apparatus according to the present invention, a driver unit (control driving means) 92 for controlling and driving the electric motor 1 is mounted near the power supply section 13 in a form integrated with the housing A. . FIGS. 2 and 3 are explanatory views showing the mounting state of the driver unit 92. FIG.

The driver unit 92 has a structure in which an element such as an FET is disposed on a metal heat radiating plate 92a, which is potted and then covered with a synthetic resin case 92b. In this case, the reason why the FET, the ECU, and the like are potted and housed in the case 92b is that the durability of the driver unit 92 is also taken into consideration. Therefore, even when the power steering device is installed near the running surface, it can be prevented from being damaged by a stepping stone or the like.

The driver unit 92 is provided with a power supply coupler 92c and a signal line coupler 92d.
Connected to another electrical system (not shown). These couplers 92c and 92d may be male or female. Further, from the driver unit 92, a terminal plate 92e for supplying power to the electric motor 1 is drawn out.

Next, in the small diameter portion 93a of the housing A,
A pedestal 94 for mounting the driver unit 92 is formed integrally with the small diameter portion 93a. Also, housing A
A power supply opening 95 communicating with the inside of the housing A is provided on an end surface 93c of the large diameter portion 93b. As a result, as shown in FIG. 2, the driver unit 92 holds the screw 9 with the terminal plate 92 e inserted into the power supply opening 95.
6 secures on the pedestal 94. At this time, the pedestal 94
The radiator plate 92a of the driver unit 92 is directly mounted on the upper part. For this reason, in the power steering device, heat generated by the FET or the like is quickly radiated from the housing A, and heat radiation of the driver unit 92 is ensured. Therefore, the driver unit 92 can be formed without providing any other heat radiating portion, and the size thereof can be minimized. Therefore, the driver unit 92 can be mounted within the size of the large diameter portion 93b of the housing A without interfering with other components. Since the driver unit 92 is mounted outside the housing A, the driver unit 92 can be protected from brush abrasion powder.

The terminal plate 92e inserted into the housing A via the power supply opening 95 is in a state of facing the terminal 91 of the brush 23 as shown in FIG. Then, by connecting these, the driver unit 9 is connected.
2 and the electric motor 1 are electrically connected. That is, here, the wiring between the control device and the motor can be reduced,
It is possible to reduce noise and increase system efficiency. An O-ring 97 is interposed between the power supply opening 95 and the driver unit 92, so that the power supply opening 95 is sealed in a watertight manner.

On the other hand, the large diameter portion 93b of the housing A
A second opening 98 is provided facing the power supply unit 13 of the electric motor 1. The sliding contact between the commutator 22 and the brush 23 can be seen from the second opening 98. Therefore, the state of the power supply unit 13 can be visually recognized through the second opening 98, and maintenance can be easily performed. In addition, from the second opening 98, FIG.
The terminal plate 92e and the terminal 91 in such a state are also visible. For this reason, spot welding can be performed between the terminal plate 92e and the terminal 91 using the second opening 98, and this operation can be performed after the electric motor 1 is assembled.

The second opening 98 has a cover 9
9 is attached. The cover 99 is attached by screws 100, and O is provided between the housing A and the cover 99.
A ring 101 is interposed.

When the driver unit 92 is mounted on the pedestal 94, the driver unit 92 is restricted in the axial direction and its end face is pressed against the end face 93c of the housing A in order to improve the sealing performance of the O-ring 97. Is also good. FIG. 4 is an explanatory diagram showing the mode. In this case, in FIG.
And regulates the driver unit 92 between the step portion 94a and the end surface 93c. In FIG. 4B, the driver unit 92 is regulated by forming a step portion 94a and forming an end surface 93c in a tapered shape. Further, in FIG. 4C, the step portion 94a is formed in a tapered shape.

Next, similarly to the housing A, the housing B is a hollow member made of aluminum die-cast, and has a ball screw mechanism 3 incorporated therein. The ball screw mechanism 3 includes a nut 19, a screw 30 formed on the outer periphery of the rack shaft 2, the nut 19 and the screw 3.
0 and a number of balls 31 interposed therebetween. The rack shaft 2 is supported by the nut portion 19 so as to be reciprocally movable in the left-right direction while the rotation around the shaft is restricted, and moves in the left-right direction with the rotation of the nut portion 19.

The nut portion 19 is held rotatably around the axis with respect to the housing B via an angular bearing 4 fixed to the housing B. That is, the power steering device has a configuration in which the nut portion 19 of the ball screw mechanism 3 and the angular bearing 4 are integrated and provided in a housing B formed separately from the housing A. .

On the other hand, the power steering device operates as follows. That is, first, the steering handle is operated to rotate the steering shaft 5, and the rack shaft 2 moves in a direction corresponding to the rotation to perform the steering operation. When a steering torque sensor (not shown) is operated by this operation, a signal is transmitted to the driver unit 92, and the driver unit 92 supplies power to the commutator 22 via the brush 23 according to the detected torque. As a result, the electric motor 1 operates to rotate the armature shaft 11, and the nut 19 connected thereto also rotates. When the nut portion 19 rotates, the steering assist force is transmitted to the rack shaft 2 by the action of the ball screw mechanism 3, and the movement of the rack shaft 2 is promoted, and the steering force is assisted.

(Embodiment 2) Next, as Embodiment 2, an arrangement will be described in which the brush holder 41 and the driver unit 92 can be inserted and fitted.
FIG. 5 is an explanatory diagram showing an attached state of the driver unit 92 in the electric power steering device according to Embodiment 2 of the present invention. The same members and portions as in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 5, in this embodiment, the back side of the brush holder 41 (opposite the brush 23).
A male terminal 102 electrically connected to the brush 23 is formed. The male terminal 102 is used for the brush holder 4
When the housing 1 is mounted in the housing A, the housing 1 is inserted into the power supply opening 95 from inside the housing A and protrudes out of the housing A therefrom. On the other hand, on the driver unit 92 side,
A female terminal (not shown) that fits with the male terminal 102 is formed. Then, the driver unit 92 is fixed on the pedestal 94 in a state where the female terminal is fitted to the male terminal 102.

FIG. 6 shows a modification of the embodiment. FIG. 6A shows the female coupler 10 on the back of the brush holder 41.
3 and the male terminal 10 of the driver unit 92 is provided there.
4 are fitted. In this case, the female coupler 103 may be configured to stay in the housing A or to protrude from the housing A. However, when the female coupler 103 protrudes, a recess for receiving the female coupler 103 is required on the driver unit 92 side.

In FIG. 6B, a coupler holder 105 is formed on a surface of the brush holder 41 on the brush 23 side, and a female coupler 106 connected to the brush 23 is accommodated therein. A socket hole 107 is formed on the back side of the brush holder 41 so as to correspond to the female coupler 106.
Then, the male terminal 104 of the driver unit 92 is inserted into the socket hole 107 and fitted with the female coupler 106.

5 and 6, unlike the first embodiment, the driver unit 92 can be attached without particularly providing the second opening 98. Of course, it is also possible to provide it separately.

The present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[0040]

A power supply opening is formed in a portion of the housing facing the power supply portion of the motor, and the driver unit is integrated with the housing in a state where the power supply portion is electrically connected to the power supply portion of the motor through the power supply opening. With this arrangement, the driver unit can be provided integrally with the housing without impairing the assembling workability, even in the case of an electric power steering device in which the power supply unit is incorporated in the back of the housing.
In addition, this allows the driver unit to be provided outside the housing at a distance from the power supply unit, so that the driver unit can be protected from brush abrasion powder.

On the other hand, a second opening is formed at a portion of the housing facing the power supply portion of the motor so that a sliding contact portion between the commutator and the brush of the motor can be visually recognized. The contact state can be visually confirmed, and the maintenance is facilitated. Further, the terminal plate of the driver unit and the contact plate of the brush can be welded using the second opening.

Further, by disposing the control drive element of the driver unit on a metal radiator plate and mounting the driver unit on the housing with the radiator plate in direct contact with the housing, the heat radiation of the driver unit is reduced. Can be secured.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a part of the entire configuration of an electric power steering device according to a first embodiment of the present invention in a cross section.

FIG. 2 is an explanatory diagram showing an attached state of a driver unit.

FIG. 3 is an explanatory diagram showing a relationship between a terminal plate of a driver unit and a contact plate of a brush holder.

FIGS. 4A to 4C are explanatory views showing a mounting mode of a driver unit.

FIG. 5 is an explanatory diagram showing a mounted state of a driver unit in the electric power steering device according to the second embodiment of the present invention;

FIGS. 6A and 6B are explanatory views showing a modification of the electric power steering apparatus according to the second embodiment.

FIG. 7 is an explanatory diagram showing a part of the entire configuration of a conventional electric power steering device in a cross section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric motor 2 Rack shaft 3 Ball screw mechanism 4 Angular bearing 5 Steering shaft 6 Coupling part 7 Motor yoke 10 Mounting hole 11 Armature shaft 12 Field device 13 Feeding part 14 Magnet 15 Armature core 17 Bearing 19 Nut part 22 Commutator 23 Brush 30 Screw part 31 Ball 41 Brush holder 51 Rack shaft 52 Electric motor 53 Ball screw mechanism 54 Steering shaft 55 Yoke 56 Armature shaft 57 Field device 58 Feeding part 59 Magnet 60 Armature core 61 Brush 62 Commutator 63 Brush holder 64 Pigtail 65 Terminal plate 66 Housing 67 Coupler 91 Terminal 92 Driver unit (control drive means) 92a Heat sink 92b Case 92c Power supply coupler 92d Signal line cap La 92e Terminal plate 93a Small diameter portion 93b Large diameter portion 93c End face 94 Pedestal 94a Step 95 Power supply opening 96 Screw 97 O ring 98 Second opening 99 Cover 100 Screw 101 O ring 102 Male terminal 103 Female coupler 104 Male terminal 105 Coupler holder 106 Female coupler 107 Socket hole A Housing (first housing) B Housing (second housing)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Wataru Mochizuki 1-268, Hirosawa-cho, Kiryu-shi, Gunma F-term (reference) Mitsuba Co., Ltd. 3D033 CA02 JB01 JB02

Claims (4)

[Claims] 1. A rack shaft connected to a steering wheel, a rack shaft movably accommodated therein, and a rack tooth formed on the rack shaft meshed with a pinion of a steering shaft connected to a steering handle. A first housing for holding the coupling portion, an electric motor disposed coaxially around the rack shaft in the first housing, for supplying a steering assist force to the rack shaft, and being connected to an armature shaft of the electric motor. A ball screw mechanism that connects the nut portion and the screw portion formed on the rack shaft with a ball member interposed therebetween and transmits the rotational force of the electric motor to the rack shaft as steering assisting force; and the ball screw. An electric power steering apparatus comprising: a second housing accommodating a mechanism; wherein the first housing is provided at a position facing a power supply unit of the electric motor; A power supply opening formed so as to communicate with the first housing, a control drive unit for controlling and driving the electric motor is provided integrally with the first housing outside the first housing, and the control drive unit is provided with the control drive unit. An electric power steering device electrically connected to the power supply unit through the power supply opening. 2. The electric power steering apparatus according to claim 1, wherein the first housing has a sliding contact portion between a commutator and a brush of the electric motor at a portion facing a power supply portion of the electric motor. An electric power steering device further comprising a second opening. 3. The electric power steering apparatus according to claim 2, wherein the control drive unit is inserted into the first housing through the power supply opening and is visible from the second opening. An electric power steering device comprising a terminal plate, wherein the terminal plate is welded to the contact plate electrically connected to the brush of the electric motor using the second opening. 4. The electric power steering apparatus according to claim 1, wherein said control drive means arranges an element for controlling and driving said electric motor on a metal radiator plate. An electric power steering apparatus, wherein the control driving means is mounted on the first housing by bringing the heat radiating plate into direct contact with the first housing.