JP2002114164A - Motor-driven power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that abnormal sound due to backlash of a speed reducing gear is transmitted to the interior of a vehicle compartment in a column type motor-driven power steering device in which a speed reducing mechanism from a motor is disposed in the lower part of a steering column. SOLUTION: An annular elastic member 17 is previously mounted in a support hole 16 of a lower bracket 15 fixed to the car body. A projecting part 14 is provided on the bottom of a housing 7 for storing the speed reducing mechanism 6. The projecting part 14 is inserted in the elastic member 17, and the housing 7 is elastically supported through the elastic member 17. Transmission of vibration is restrained by the elastic member 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called column type electric power steering apparatus in which a steering column is equipped with a motor for generating a steering assist force.

[0002]

2. Description of the Related Art In a so-called column type electric power steering apparatus, a reduction mechanism is accommodated in a housing fixed to a lower portion of a steering column, and the housing is used to generate a steering assist force. The motor is supported. The upper part of the steering column is rigidly fixed to the vehicle body via an upper bracket, and the housing is rigidly fixed to the vehicle body via a lower bracket.

[0003] Incidentally, the gear of the speed reduction mechanism has play due to backlash, and there is a possibility that abnormal noise is generated due to the hitting sound due to this play. Especially in the column type,
Since the housing incorporating the above-described speed reduction mechanism is arranged in the vehicle, the above-mentioned abnormal noise is likely to cause a problem. Conventionally, as a countermeasure against this abnormal noise, the dimensional accuracy of each part of the power transmission path is improved. Further, in order to improve the assembly accuracy, parts having actually measured dimensions which are preferable combinations are selected, and these parts are combined.
Further, a mechanism for adjusting the backlash is incorporated in the speed reduction mechanism. However, in either case, there is a problem that the manufacturing cost increases.

On the other hand, it is conceivable that the motor is elastically supported by the housing. In this case, although the effect of not transmitting the operation sound of the motor itself can be expected, it is not possible to prevent the propagation of vibration and sound due to the above-mentioned gear play and the like. The present invention has been made in view of the above problems, and has as its object to provide an electric power steering device that is inexpensive and can effectively prevent abnormal noise in a vehicle compartment.

[0005]

In order to achieve the above object, the present invention provides a housing fixed to a lower portion of a steering column and accommodating at least a speed reduction mechanism, and a steering assist force generated by the housing. An electric power steering apparatus comprising a motor for use in a vehicle and a support member fixed to the vehicle body and supporting the housing to the vehicle body, wherein an elastic member is interposed between the support member and the housing. is there.

In this configuration, the elastic member suppresses the transmission of vibration between the housing accommodating the speed reduction mechanism and the support member.
Therefore, vibration from the housing, which causes abnormal noise, is not transmitted to the vehicle body. As a result, it is possible to prevent the generation of unpleasant noise in the vehicle interior. Moreover, this can be achieved at a low cost by a simple method of simply interposing an elastic member. It is preferable that the housing has a protrusion inserted into a support hole provided in the support member, and the elastic member be formed in an annular shape and be interposed between the outer periphery of the protrusion and the inner periphery of the support hole. In this case, it is only necessary to insert the convex portion of the housing into the annular elastic member attached to the support hole in advance, so that the work of assembling the electric power steering device to the vehicle body becomes very easy.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a partially cut-away schematic sectional view of an electric power steering apparatus according to an embodiment of the present invention. Referring to FIG. 1, an electric power steering apparatus 1 includes a steering shaft 2 having a steering wheel attached to an upper end portion so as to be integrally rotatable, and a steering column 3 rotatably supporting the steering shaft 2. .

The upper portion of the steering column 3 is fixed to the vehicle body side member 5 via the upper bracket 4, whereby the upper portion of the steering column 3 is supported by the vehicle. Although not shown, a shock absorbing mechanism having a known capsule structure is disposed at a mounting portion between the upper bracket 4 and the vehicle body side member 5. A housing 7 accommodating at least the speed reduction mechanism 6 is fixed to a lower portion of the steering column 3, and the housing 7 supports a motor 8 for generating a steering assist force. Specifically, a housing containing a rotor and a stator of the motor 8 is integrally fixed to or integrally formed with the housing 7 that houses the speed reduction mechanism 6. The rotation of the motor 8 is given to the output shaft 9 in a state where the rotation is reduced via the reduction mechanism 6.

On the other hand, an input shaft (not shown) integrally rotatably connected to the lower end of the steering shaft 2 and an output shaft 9 connected to the input shaft via a torsion bar are built in the housing 7. . The lower end of the output shaft 9 protrudes below the housing 7 and is connected to, for example, a rack and pinion mechanism as a steering mechanism via a universal joint (not shown). A rolling bearing 10 rotatably supports the output shaft 9 in the housing 7. 1
Reference numeral 1 denotes a torque sensor for detecting a relative displacement generated between the input shaft and the output shaft 9 during steering. The input current to the motor 8 is controlled based on the signal from the torque sensor 11, thereby generating a steering assist force according to the steering torque applied to the steering shaft 2.

[0010] As the speed reduction mechanism 6, for example, the worm gear 1 that is integrally rotatably connected to the rotation shaft of the motor 8.
A worm mechanism including the worm gear 2 and a worm wheel 13 that meshes with the worm gear 12 and is integrally rotatably connected to the output shaft 9 can be exemplified. Housing 7
Is provided with an annular convex portion 14 on the lower surface thereof.
4 is inserted as a support member into a support hole 16 of a lower bracket 15 rigidly fixed to the vehicle body. An annular elastic member 17 is interposed between the outer periphery of the projection 14 and the inner periphery of the support hole 16, and the housing 7 is elastically supported by the vehicle body via the elastic member 17. As the elastic member 17, a synthetic rubber or a synthetic resin can be used, and a foam may be used.

Referring to FIG. 2, which is an enlarged view, an elastic member 1 is shown.
The inner peripheral surface 18 of 7 is in close contact with the outer peripheral surface 19 of the convex portion 14, and the outer peripheral surface 20 of the elastic member 17 is formed with a peripheral groove 21 into which the peripheral edge 16 a of the support hole 16 is fitted. The elastic member 17 has a pair of side walls 22 and 23 that define the peripheral groove 21, and these side walls 22 and 23 sandwich the peripheral edge 16 a of the support hole 16 from both sides. According to the present embodiment, the transmission of the gear vibration of the reduction mechanism 6 from the housing 7 to the lower bracket 15 can be prevented by the elastic member 17.
Therefore, vibration from the housing 7 that causes abnormal noise is not transmitted to the vehicle body. As a result, it is possible to prevent the generation of unpleasant noise in the vehicle interior. Moreover, this can be achieved by merely interposing the elastic member 17 without the need to extremely increase the dimensional accuracy in order to eliminate the backlash unlike the related art, and the manufacturing cost can be reduced.

In particular, the support hole 16 of the lower bracket 15
It is only necessary to insert the convex portion 14 at the bottom of the housing 7 into the annular elastic member 17 set in advance, so that the work of assembling the electric power steering device 1 to the vehicle body becomes very easy. From this point as well, the manufacturing cost can be reduced by reducing the assembly cost. Note that the present invention is not limited to the above embodiment. For example, in a type in which a steering column is divided into two vertically, a bracket for stopping rotation of a lower column is provided with a member on a vehicle body side. You may be made to attach to. In this case, it is preferable to interpose an elastic member also between the bracket and the member on the vehicle body side, but it is not particularly limited to this. In addition, various changes can be made within the scope of the claims of the present invention.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of an electric power steering device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an elastic member and its periphery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric power steering device 2 Steering shaft 3 Steering column 4 Upper bracket 5 Body side member 6 Reduction mechanism 7 Housing 8 Motor 9 Output shaft 12 Worm gear 13 Worm wheel 14 Convex part 15 Lower bracket (support member) 16 Support hole 17 Elastic member

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Seiji Fujioka 3-5-8 Minamisenba, Chuo-ku, Osaka-shi Inside Koyo Seiko Co., Ltd. (72) Inventor Takashi Tsutsui 3-58 Minamisenba, Chuo-ku, Osaka-shi Koyo Seiko Co., Ltd. F term (reference) 3D033 CA02 CA04 CA16

Claims (2)

[Claims] A housing fixed to a lower portion of a steering column and accommodating at least a speed reduction mechanism; a motor for generating a steering assist force supported by the housing; and a support member fixed to the vehicle body and supporting the housing to the vehicle body. An electric power steering apparatus comprising: an elastic member interposed between the support member and the housing. 2. The housing according to claim 1, wherein the housing has a convex portion inserted into a support hole provided in the support member, and the elastic member forms an annular shape and has an outer periphery of the convex portion and an inner periphery of the support hole. An electric power steering device characterized by being interposed therebetween.