JP2000038145A - Electric power steering device - Google Patents

Abstract

(57) [Problem] To provide an electric power steering device which prevents leakage of a grease oil component from a reduction gear box. A lubricating oil absorbing material (71) is provided adjacent to a rear bearing (43) in an intermediate hole (53) of a gear box cover (33).
Is inserted. The lubricating oil absorbing material 71 is composed of an outer ring made of steel or synthetic resin, and a synthetic resin brush implanted on the inner peripheral surface of the outer ring. Is in sliding contact. The lubricating oil attached to the rear bearing 43 moves forward by gravity from the space between the outer ring 45 and the inner ring 61 and the gap between the inner ring 61 and the output shaft 17, and flows into the intermediate hole 53. However, since the lubricating oil absorbing material 71 is fitted into the intermediate hole 53, the grease oil component that has flowed in is captured by the brush of the lubricating oil absorbing material 71 by the action of surface tension, and does not flow out to the front bearing 41 side.

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 apparatus used for an automobile or the like, and more particularly to a technique for preventing a grease oil component from leaking from a reduction gear box.

[0002]

2. Description of the Related Art In a steering system for an automobile, a so-called power steering device for performing steering assist using an external power source is widely used. Conventionally, a vane type hydraulic pump is generally used as a power source for a power steering device, and many hydraulic pumps are driven by an engine. However, this type of power steering apparatus has a large engine drive loss due to the constant drive of the hydraulic pump (about several horsepower to about ten horsepower at the maximum load), and is therefore adopted for a light vehicle with a small displacement. It is difficult, and even in a small car with a relatively large displacement, it is inevitable that the running fuel efficiency is reduced to a level that cannot be ignored. In order to solve these problems, an electric power steering apparatus using an electric motor as a power source (hereinafter, referred to as EPS: Electric Power) has been proposed.
Steering system) is being developed. In the EPS, the in-vehicle battery is used as a power source for the electric motor, so that there is no direct engine drive loss, and the electric motor is started only at the time of steering assist. Loss) is also reduced.

[0003] EPS is classified into a column assist type, a pinion assist type, and the like according to a mounting portion of the electric motor.
Assist is provided to a steering shaft, a steering gear pinion and the like according to the type. In the column assist type EPS, a part of a steering column is formed by a reduction gear box, and an electric motor is attached to the reduction gear box. The rotation of the electric motor is transmitted to an output shaft forming a part of the steering shaft after being reduced by a worm reduction mechanism housed in a reduction gear box. Usually, the reduction gear box is divided into a gear box body and a gear box cover, and a worm pinion, a worm wheel, a torque sensor, etc. are arranged on the gear box body side, while an output shaft is rotated on the gear box cover side. A freely supported bearing (generally, a ball bearing) is held.

[0004]

The above-described electric power steering apparatus has a problem that the grease oil component in the reduction gear box leaks along the output shaft. Normally, in the reduction gear box, a relatively large amount of grease is applied to these components in order to lubricate the worm reduction mechanism and the torque sensor. Therefore, when the operation is performed for a long period of time, the grease oil component scatters from the worm reduction mechanism or the torque sensor into the reduction gear box, and the grease oil component scattered because the steering shaft is disposed vertically or inclined forward. Flows to the gear box cover side in the reduction gear box. Generally, a sealing member such as an O-ring or packing is interposed between the gear box body and the gear box cover, while a dust-proof seal is provided on the bearing on the gear box cover side to prevent intrusion of dust from the outside. It is installed. However, the relatively low-viscosity grease oil component leaks through the gap between the dust-proof seal and the bearing inner ring or the gap between the bearing inner ring and the output shaft, and drops from the output shaft through the lower steering shaft into the vehicle interior. become. In this case, the floor carpet and the like may be contaminated with the lubricating oil, and dust may adhere to the universal joint and the like, and wear of the sliding portion and the like may be accelerated. The present invention has been made in view of the above circumstances, and has as its object to provide an electric power steering device that prevents leakage of a grease oil component from a reduction gear box.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, according to the present invention, a reduction gear box forming a part of a steering column, and an electric motor mounted on the reduction gear box are provided. An output shaft penetrating the reduction gear box and forming a part of a steering shaft; a worm pinion housed in the reduction gear box and coupled to the electric motor; and a worm coupled to the output shaft. In an electric power steering apparatus having a reduction mechanism including a wheel and a bearing held by the reduction gear box and rotatably supporting the output shaft, a lubricating oil absorbing material is provided at a portion of the reduction gear box outside the bearing. Propose the one with. According to the present invention, the grease oil component leaked from the gap between the dust-proof seal and the bearing inner ring or from the gap between the bearing inner ring and the output shaft is impregnated and held in the lubricating oil absorbent, and does not flow out of the reduction gear box.

According to the second aspect of the present invention, the lubricating oil-absorbing material has a brush-shaped or sponge-shaped absorbing material body which is in sliding contact with the output shaft, fixed to an inner peripheral surface of an annular body made of metal or synthetic resin. Propose what can be done. In this invention, the leaked grease oil component is held by the brush-shaped absorbent main body or absorbed by the sponge-shaped absorbent main body due to surface tension.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing a cabin-side portion of the steering device according to the first embodiment, and reference numeral 1 in the figure denotes a tilted steering column. The steering column 1 is a steel pipe upper steering column (hereinafter abbreviated as upper column) 7 fixed to the vehicle body side member 5 via a steel plate upper bracket 3.
And the vehicle body side member 5 via the steel plate lower bracket 9.
Gear box 11 made of cast aluminum alloy fixed to
It is composed of A shock absorbing mechanism (collapsible mechanism) is incorporated in the steering device according to the present embodiment, and a resin pin (not shown) is broken at the time of a secondary collision or the like, and the upper column 7 falls off. Details are omitted. In the figure, the member denoted by reference numeral 13 is:
The bellows is made of a steel plate for absorbing impact energy and interposed between the upper column 7 and the reduction gear box 11.

An upper steering shaft 15 is rotatably supported by the upper column 7, and an output shaft 17 is rotatably supported by the reduction gear box 11. Also, the upper steering shaft 15
A steering wheel 19 is attached to a rear end of the output shaft 17, and a lower steering shaft 23 is connected to a front end of the output shaft 17 via a universal joint 21.
Are connected. The reduction gearbox 11 is composed of a gearbox body 31 having a steel plate bellows 13 fixed to an upper end.
And a gear box cover 33 bolted to the gear box body 31 together with the lower bracket 9. The gear box cover 33 has a built-in worm reduction mechanism including a worm pi 37 and a worm wheel 39 and a torque sensor (not shown) in addition to the electric motor 35 attached to the side surface thereof. The gear box cover 33 holds a pair of front and rear deep groove ball bearings (hereinafter simply referred to as bearings) 41 and 43 for rotatably supporting the output shaft 17.

As shown in FIG. 2 (a partially enlarged view in FIG. 1), the gear box cover 33 is formed with a pair of front and rear bearing holding holes 49 and 51 having relatively large diameters at its axial center. The intermediate hole 5 having a relatively small diameter between the bearing holding holes 49 and 51.
It is 3. The front and rear bearings 41 and 43 have outer rings 45 and 47 respectively fitted into front and rear bearing holding holes 49 and 51 from front and rear. Then, the inner rings 61 and 63 are tightened by a pair of front and rear lock nuts 57 and 59 screwed to the screw portion 55 formed at the tip of the output shaft 17, whereby preload is applied to both bearings 41 and 43. At the same time, the output shaft 17 and the worm wheel 39 are positioned. In FIG.
The member indicated by the reference numeral 65 is a torsion bar constituting the torque sensor.

In the case of the first embodiment, a lubricating oil absorbing material 71 is fitted in the intermediate hole 53 of the gear box cover 33 so as to be adjacent to the rear bearing 43. Lubricating oil absorber 7
1 is an outer ring (annular body) 73 made of steel or synthetic resin and an inner periphery of the outer ring 73, as shown in FIG. 3 (front view) and FIG. And a brush 75 made of synthetic resin implanted on the surface.
Are in sliding contact with the outer peripheral surface of the output shaft 17. In FIG. 2, a member indicated by reference numeral 77 is an O-ring interposed on a joint surface between the gear box body 31 and the gear box cover 33, and a member indicated by reference numeral 79 is an inner periphery of the rear bearing holding hole 51. An O-ring held on the surface. still,
The front bearing 41 is of a dustproof type, and a dustproof seal 81 is attached to the front surface thereof.

The operation of the first embodiment will be described below. When the driver rotates the steering wheel 19, the driver turns the steering wheel 19 through the upper steering shaft 15, the sensor output shaft 17, and the lower steering shaft 23.
The rotational force is transmitted to a steering gear (not shown). In the steering gear, a rack and pinion mechanism etc. that converts rotation input into linear motion is built in,
Steering is performed by changing the steering angle of the wheel via the tie rod. At this time, the electric motor 35 rotates with a predetermined rotational torque in either the forward or reverse direction based on the detection signal of the torque sensor in the reduction gear box 11, the vehicle speed, and the like, and the rotation is transmitted to the sensor output shaft 17 via the reduction gear. And thereby steering assist is realized.

Now, when steering is performed in this way,
A large amount of lubricating oil applied to the worm pinion 37, the worm wheel 39, the torque sensor and the like scatters around, and the lubricating oil adheres to the inner surfaces of the gear box body 31 and the gear box cover 33. Then, the lubricating oil attached to the rear bearing 43 moves forward by gravity from the space between the outer ring 45 and the inner ring 61 and the gap between the inner ring 61 and the output shaft 17, and flows into the intermediate hole 53. . However, in the case of the present embodiment, the intermediate hole 53
The lubricating oil absorbing material 71 is inserted into the lubricating oil absorbing material 71, and the inflowing lubricating oil is captured by the brush 75 of the lubricating oil absorbing material 71 by the action of surface tension, and does not flow out to the front bearing 41 side. Although the lubricating oil also flows into the gap between the outer ring 47 of the rear bearing 43 and the rear bearing holding hole 51, it flows forward by the O-ring 79 held on the inner peripheral surface of the rear bearing holding hole 51. Is blocked.

As described above, in the first embodiment, the leakage of the lubricating oil to the outside of the gear box 11 is effectively prevented while adopting a relatively simple structure, and the floor carpet and the like are contaminated, and the dust to the universal joint is prevented. Has been prevented.

FIG. 5 is a longitudinal sectional view showing a main part of the steering device according to the second embodiment. In the present embodiment, bearings 41 and 43 are disposed before and after the worm wheel 39 (that is, on the gear box cover 33 and the gear box main body 31), and the preload of the bearings 41 and 43 and the positioning of the worm wheel 39 are determined by a cylinder. The adjustment is performed by an adjusting screw 83 having a shape of a circle. In the case of the second embodiment, the lubricating oil absorbent 71 is fitted on the inner peripheral surface of the adjusting screw 83, and the lubricating oil flowing out of the front bearing 41
Similar to the embodiment, it is supplemented by the brush 75 of the lubricating oil absorbent 71. In this embodiment, an O-ring 79 is provided on the inner peripheral surface of the front bearing holding hole 49 in order to prevent the lubricating oil from flowing out from the gap between the outer ring 45 of the front bearing 41 and the front bearing holding hole 49. The O-ring 79 may be held on the outer peripheral surface of the rear part of the adjusting screw 83 as shown in FIG.

FIG. 7 is a longitudinal sectional view showing a main part of a steering device according to a third embodiment. In this embodiment, substantially the same configuration as that of the first embodiment is adopted, but the mounting position of the lubricating oil absorbent 71 is different. That is, in the present embodiment, the gear box cover 33 extends slightly forward, and the lubricating oil absorbent 71 is provided on the inner peripheral surface of the front bearing holding hole 49 so as to be adjacent to the front surface of the front bearing 41. It is inserted. The brush 75 of the lubricating oil absorbent 71 is in sliding contact with the outer peripheral surface of the rear lock nut 59, and the lubricating oil flowing out of the front bearing 41 is captured by the brush 75 as in the first embodiment.

FIG. 8 is a front view showing a modification of the lubricating oil absorber, and FIG. 9 is a cross-sectional view taken along the line CC in FIG. As shown in these figures, the lubricating oil absorbing material 71 of this modification example
Is an outer ring 73 made of steel or synthetic resin and the outer ring 7
3 and a sponge 85 made of synthetic resin fixed to the inner peripheral surface of the sponge. In the lubricating oil absorbing material 71, the outflowing lubricating oil is absorbed and held by the sponge 85, so that substantially the same effects as those using the brush 75 described above can be obtained.

The description of the specific embodiment has been completed.
The aspects of the present invention are not limited to the above embodiment.
For example, in each of the above embodiments, the present invention is applied to a gear box cover holding a bearing disposed at the front of the reduction gear box, but the gear box cover is disposed at the rear of the reduction gear box. Alternatively, the bearing may be applied to a bearing held on the side of the gear box body, in which case the gear box body is provided with a lubricating oil absorbing material. Further, a fibrous material represented by glass wool or the like may be used as a material of the lubricating oil absorber, and an angular ball bearing, a tapered roller bearing, or the like may be used as a bearing. Further, the specific shape and the like of the reduction gear box and the mounting portion of the lubricating oil absorbing material can be appropriately changed without departing from the gist of the present invention.

[0018]

As described above, according to the electric power steering apparatus of the present invention, the reduction gear box forming a part of the steering column, the electric motor mounted on the reduction gear box, and the reduction gear An output shaft that penetrates the gearbox and forms a part of the steering shaft, a worm pinion housed in the reduction gearbox and coupled to the electric motor, and a worm wheel coupled to the output shaft In the electric power steering apparatus having a speed reduction mechanism and a bearing held by the speed reduction gear box and rotatably supporting the output shaft, a lubricating oil absorbing material is provided in a portion of the speed reduction gear box outside the bearing. The dust-proof seal and the inside of the bearing Lubricating oil leaked from the gap between the gap and the bearing inner ring and the output shaft with the impregnated and held in the lubricating oil absorbent material will not flow out of the reduction gear box.

[Brief description of the drawings]

FIG. 1 is a side view showing a passenger compartment side portion of a steering device according to a first embodiment.

FIG. 2 is an enlarged sectional view of a portion A in FIG.

FIG. 3 is a front view of a lubricating oil absorber.

FIG. 4 is a sectional view taken along line BB in FIG. 3;

FIG. 5 is a longitudinal sectional view showing a main part of a steering device according to a second embodiment.

FIG. 6 is an enlarged view of a main part showing a partially modified example of the second embodiment.

FIG. 7 is a longitudinal sectional view showing a main part of a steering device according to a third embodiment.

FIG. 8 is a front view showing a modification of the lubricating oil absorber.

9 is a sectional view taken along the line CC in FIG. 8;

[Explanation of symbols]

 11 ‥‥ reduction gear box 17 ‥‥ output shaft 31 ‥‥ gear box body 33 ‥‥ gear box cover 35 ‥‥ electric motor 37 ‥‥ worm 39 ‥‥ worm wheel 41, 43 ‥‥ deep groove ball bearing 49, 51 ‥‥ Bearing holding hole 53 Intermediate hole 71 Lubricating oil absorber 73 Outer ring 75 Brush 79 O-ring 83 Adjust screw 85 Sponge

Claims (2)

[Claims] 1. A reduction gear box forming a part of a steering column, an electric motor attached to the reduction gear box, and an output shaft penetrating the reduction gear box and forming a part of a steering shaft. A reduction mechanism that is housed in the reduction gear box and includes a worm pinion coupled to the electric motor and a worm wheel coupled to the output shaft; and a rotation mechanism that is held by the reduction gear box and rotates the output shaft. An electric power steering apparatus comprising: a bearing that is freely supported; and a lubricating oil absorbing member provided in a portion of the reduction gear box outside the bearing. 2. A brush-like or sponge-like absorbent body which is in sliding contact with said output shaft is fixed to an inner peripheral surface of an annular body made of a metal or a synthetic resin. The electric power steering device according to claim 1.