KR101424849B1

KR101424849B1 - Reducer of Electrical Power Steering Apparatus and Electrical Power Steering Apparatus having The Same

Info

Publication number: KR101424849B1
Application number: KR1020100036171A
Authority: KR
Inventors: 김길중
Original assignee: 주식회사 만도
Priority date: 2010-04-20
Filing date: 2010-04-20
Publication date: 2014-08-04
Also published as: KR20110116638A

Abstract

The present invention relates to a speed reducer of an electric power assisted steering apparatus and an electric power assisted steering apparatus having the same and, more particularly, to an electric power assisted steering apparatus having a reduction gear and a rotational resistance of a drive shaft and a worm shaft of a motor, It is possible to reduce the rattle noise generated due to the increase of the backlash caused by the wear of the worm and the worm wheel or the impact transmitted through the wheel and the steering shaft from the road surface while increasing the steering feeling of the driver.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a reduction gear of an electric power assist steering apparatus and an electric power assist steering apparatus having the same,

The present invention relates to a speed reducer of an electric power assisted steering apparatus. More particularly, the present invention relates to a reduction gear unit of an electric power assist steering apparatus, which is capable of increasing the steering feeling of a driver by reducing the sense of engagement and rotation resistance between the drive shaft and the worm shaft of the motor, And a ratchet noise generated by an impact transmitted through a wheel and a steering shaft can be reduced. [0002] The present invention relates to a reduction gear of an electric power assist steering apparatus and an electric power assist steering apparatus having the same.

1, the electric power assist steering apparatus 100 includes a steering system 130 extending from a steering wheel 102 to both wheels 126, And an auxiliary power mechanism (140) for providing steering assist power to the system (130).

The steering system 130 includes a steering shaft 106 having one side connected to the steering wheel 102 and rotating with the steering wheel 102 and the other side connected to the pinion shaft 108 via a pair of universal joints 104 ). The pinion shaft 108 is connected to the rack bar 112 via the rack pinion mechanism unit 110 and both ends of the rack bar 112 are connected to the wheels 126 of the vehicle through the tie rod 122 and the knuckle arm 124. [ Lt; / RTI >

The auxiliary power mechanism 140 includes a torque sensor 142 that senses a torque applied by the driver to the steering wheel 102 and outputs an electric signal proportional to the sensed torque and a torque sensor 142 that outputs an electric signal proportional to the sensed torque based on an electric signal transmitted from the torque sensor 142 An electronic control unit 144 for generating a control signal and a motor 146 for generating an auxiliary power based on the control signal transmitted from the electronic control unit 144 and an auxiliary power generated by the motor 146 to the steering shaft 106, And a speed reducer 150 having a worm 152 and a worm wheel 156 to transmit the worm 152 and the worm wheel 156 to each other.

Therefore, the electric power assist steering apparatus is configured such that the torque generated by the rotation of the steering wheel 102 is transmitted to the rack bar 112 via the rack pinion mechanism unit 110, and the auxiliary power generated by the motor 146 in accordance with the generated torque To the rack bar (112).

That is, the torque generated by the rotation of the steering wheel 102 and the auxiliary power generated by the motor 146 are combined to move the rack bar 112 in the axial direction.

2, the speed reducer 150 is provided with a worm shaft 254 formed with a worm 152, and a worm shaft 254 is provided at both ends of the worm shaft 254, A plug bolt 210 is fastened to prevent the worm shaft 257 from being spaced apart in the axial direction of the worm shaft 254 and the plug bolt 210 is fastened Is fixed by a plug nut (220).

The worm shaft 254 is connected to the motor 146 via a motor boss, and the worm shaft 254 is rotated by driving of the motor 146.

A worm wheel 156 is provided on one side of the outer diameter of the worm 152 so as to be engaged with the worm 152 formed on the worm axis 254. The worm wheel 156 is connected to a steering wheel And the rotational force of the worm shaft 254 due to the driving of the motor 146 is transmitted to the steering shaft 106. [

The gear housing 260 is provided with a motor 146 for providing a driving force to the worm shaft 254 at one side of the gear housing 260 and a worm 152 and a worm wheel 156. The gear housing 260 includes a gear housing 260, The motor 146 is coupled to the bolt 250 by a motor cover 230.

The speed reducer of the electric power assist steering apparatus having the above structure controls the driving of the motor by the electronic control unit provided in the vehicle according to the driving condition of the vehicle, and the rotation of the worm shaft by the driving of the motor is controlled by the steering wheel And is transmitted to the steering shaft in addition to the rotational force, so that the steering operation state of the driver can be maintained smoothly and stably.

However, in the conventional reducer of the electric power assisted steering system, errors in manufacturing and errors in assembling are accumulated in the joint portion between the worm shaft and the motor shaft, so that the drive shaft and the worm shaft of the motor are not coaxially positioned, There is a problem that the rotation resistance of the shaft increases.

In addition, when the worm and the worm wheel advance, the rattle noise is generated due to the backlash, and the rattling noise transmitted from the road surface through the wheel and the steering shaft causes the driver to operate the steering wheel There was a problem that caused discomfort.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a reduction gear of a motor-driven power assist steering apparatus which can reduce the sense of engagement and rotation resistance between a drive shaft and a worm shaft, The object of the present invention is to reduce the rattle noise caused by an increase in backlash due to abrasion or an impact transmitted from the road surface through a wheel and a steering shaft.

According to an aspect of the present invention, there is provided a steering apparatus comprising: a drive shaft of a motor generating a steering assist force; A worm shaft connected to the drive shaft to drive the worm wheel; A coupler in which the worm shaft and the end portion of the drive shaft are inserted and coupled to one side and the other side, respectively, of a hollow shape; And an elastic body inserted into an end portion of the worm shaft in a hollow shape and coupled to the coupler. [5] The power assist steering apparatus of claim 1,

According to another aspect of the present invention, there is provided an electric power assist steering apparatus including a steering shaft connected to a steering wheel, and a reduction gear connected to the steering shaft to transmit a steering assist force by a driving force of the motor, A driving shaft of the motor; A worm shaft connected to the drive shaft to drive the worm wheel; A coupler in which the worm shaft and the end of the drive shaft are inserted and coupled to one side and the other side, respectively, of the hollow shape; And an elastic body inserted into an end portion of the worm shaft in a hollow shape and coupled to the coupler.

According to the present invention, in the speed reducer of the electric power assisted steering apparatus, the sense of engagement between the drive shaft and the worm shaft of the motor and the rotational resistance are reduced to increase the steering feeling of the driver, and at the same time, the backlash is increased due to wear of the worm and the worm wheel Or the rattle noise generated by the shock transmitted from the road surface through the wheel and the steering shaft can be reduced.

1 is a block diagram of a conventional electric power assist steering apparatus;
2 is a sectional view showing a speed reducer of a conventional electric power assist steering apparatus;
3 and 4 are an exploded perspective view and a cross-sectional view illustrating a speed reducer of an electric power assisted steering apparatus according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected to or connected to the other component, It should be understood that an element may be "connected," "coupled," or "connected."

3 and 4 are an exploded perspective view and a cross-sectional view illustrating a speed reducer of an electric power assisted steering apparatus according to an embodiment of the present invention.

As shown in these drawings, the speed reducer 400 of the electric power assisted steering apparatus according to an embodiment of the present invention includes a drive shaft 270 of a motor 146 generating a steering assist force; A worm shaft 254 connected to the driving shaft 270 to drive the worm wheel 156; A coupler 330 in which the ends of the worm shaft 254 and the drive shaft 270 are inserted and coupled to one side and the other side, respectively, in a hollow shape; And an elastic body 325 inserted into an end of the worm shaft 254 in a hollow shape and coupled to the coupler 330.

The steering shaft 106 is connected to the steering wheel 106 (refer to 102 in FIG. 1). The steering shaft 106 is connected to the steering shaft 106 to generate a steering assist force The power-assisted steering apparatus including the speed reducer (400) for transmitting the power.

The speed reducer 400 is provided with a worm shaft 254 on which the worm 152 is formed and a worm shaft 257 is mounted on both ends of the worm shaft 254 to support the worm shaft 254. The worm shaft 257 supports the worm shaft 254, The plug bolts 210 are fastened and the plug bolts 210 are fastened by the plug nuts 220. [

The worm shaft 254 is connected to the drive shaft 270 of the motor 146 through a coupler 330 so that the worm shaft 254 rotates by driving the motor 146.

The coupler 330 connects the drive shaft 270 of the motor 146 generating the auxiliary power of the electric power assisted steering apparatus and the worm shaft 254 to transmit the steering assist power generated by the motor 146 to the worm wheel 156 And is transmitted to a steering shaft coupled to the worm wheel 156, thereby assisting the steering force of the driver.

The worm shaft 254 and the drive shaft 270 are inserted into one side and the other side of the coupler 330 to transmit the driving force of the motor 146 to the worm shaft 254. The motor 146 The driving shaft 270 of the worm shaft 254 is press-fitted into the coupler 330 and the elastic body 325 is coupled to the end of the worm shaft 254 and inserted into the coupler 330.

The worm shaft 254 has a first concavo-convex portion 310a extending in the axial direction and a second concavo-convex portion 310a corresponding to the first concavo-convex portion 310a at the end of the worm axis 254 is provided on the inner circumferential surface of the elastic body 325, The worm shaft 254 and the elastic body 325 are prevented from slipping.

The outer circumferential surface of the elastic body 325 is provided with a third concave-convex portion 320a which is elongated at a predetermined angle with respect to the axial direction. The inner circumferential surface of the coupler 330 is formed long in the axial direction, And a fourth concavo-convex portion 320b having irregularities at intervals corresponding to the irregular intervals of the irregular portions 320a.

The third concavoconvex portion 320a is formed on the outer circumferential surface of the elastic body 325 in the axial direction or at a predetermined angle with respect to the axial direction and is formed on the inner circumferential surface of the coupler 330 at a predetermined angle And a fourth concavo-convex portion 320b having concavities and convexities formed at intervals corresponding to concavo-convex intervals of the third concavo-convex portion 320a.

When the end of the worm shaft 254 is coupled to the coupler 330, the third concave / convex portion 320a of the elastic body 325 coupled to the outside of the end of the worm shaft 254 is elastically deformed in the axial direction, And is coupled to the fourth concave and convex portion 320b.

That is, when the third concave-convex portion 320a formed at a predetermined angle with the axial direction and formed in the helical gear tooth shape is inserted into the fourth concave-convex portion 320b in the axial direction and is coupled to the third concave- The torsional elastic force is continuously generated to support the worm shaft 254 and the coupler 330, thereby eliminating the clearance.

Therefore, even if an impact is introduced into the worm shaft 254 through the steering shaft and the worm wheel 156 from the road surface during driving of the automobile, the rattle noise is not generated and damping is performed.

The worm shaft 254 coupled to the coupler 330 and the drive shaft 270 of the motor 146 may not be positioned on the same axis due to the torsional elastic force of the elastic body 325, The elastic body 325 moves the rotation center on the drive shaft 270 of the motor 146 so that the driving force of the motor 146 can be stably transmitted to the worm shaft 254 while the worm shaft 254 is driven. As shown in FIG.

In this case, the elastic body is formed in a hollow shape so that the worm shaft end is inserted, and is made of NR (Natural Rubber), NBR (Nitrile Butadiene Rubber), CR (Chloroprene Rubber), EPDM (Ethylene Propylene Terpolymer) Elastomer, SBR (Styrene Butadine Rubber), CSM (Chlorosulphonated Polyethylene), silicone, urethane or the like, and acts as a damping between the worm shaft and the driving shaft 270.

One embodiment of the present invention includes a steering shaft 106 connected to a steering wheel and the speed reducer 400 connected to the steering shaft 106 to transmit a steering assist force by a driving force of a motor Thereby constituting an electric power assist steering device.

According to the present invention having such a structure and configuration, in the speed reducer of the electric power assisted steering apparatus, the sense of engagement and the rotational resistance between the drive shaft and the worm shaft of the motor are reduced to increase the steering feeling of the driver, It is possible to reduce the rattle noise generated by the increase of the backlash or the impact transmitted from the road surface through the wheel and the steering shaft.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them.

It is also to be understood that the terms such as " comprises, "" comprising," or "having ", as used herein, mean that a component can be implanted unless specifically stated to the contrary. But should be construed as including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

146: motor 254: worm shaft
270: drive shaft 310a: first concave-
310b: second uneven portion 320a: third uneven portion
320b: fourth concave-convex portion 325: elastic body
330: Coupler

Claims

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A steering shaft connected to a steering wheel; and a speed reducer connected to the steering shaft for transmitting a steering assist force by a driving force of the motor,
The speed reducer includes:
A driving shaft of the motor;
A worm shaft connected to the drive shaft to drive the worm wheel;
A coupler in which the worm shaft and the end of the drive shaft are inserted and coupled to one side and the other side, respectively, of the hollow shape; And
And an elastic body inserted into an end of the worm shaft in a hollow shape and coupled to the coupler,
Wherein the end of the worm shaft has a first concavo-convex portion that is elongated in the axial direction, the elastic body has a second concavo-convex portion corresponding to the first concavo-
Wherein the elastic body has a third concavo-convex portion formed on the outer circumferential surface at a predetermined angle with respect to the axial direction, the coupler having a concavo-convex portion formed at an interval corresponding to the convexo-concave portion of the third concavo-convex portion, Wherein the fourth concavo-convex part is elastically deformed in the axial direction when the worm shaft and the coupler are coupled, and is engaged with the fourth concave-convex part.

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A steering shaft connected to a steering wheel; and a speed reducer connected to the steering shaft for transmitting a steering assist force by a driving force of the motor,
The speed reducer includes:
A driving shaft of the motor;
A worm shaft connected to the drive shaft to drive the worm wheel;
A coupler in which the worm shaft and the end of the drive shaft are inserted and coupled to one side and the other side, respectively, of the hollow shape; And
And an elastic body inserted into an end of the worm shaft in a hollow shape and coupled to the coupler,
Wherein the end of the worm shaft has a first concavo-convex portion that is elongated in the axial direction, the elastic body has a second concavo-convex portion corresponding to the first concavo-
The elastic body has a third concavo-convex portion formed on the outer circumferential surface in the axial direction. The coupler is formed on the inner circumferential surface at a predetermined angle with the third concavo-convex portion, and concave and convex portions are formed at intervals corresponding to the concave- Wherein the third concave-convex portion of the elastic body is elastically deformed in the axial direction when the worm shaft and the coupler are coupled, and is engaged with the fourth concave-convex portion.