KR101315666B1

KR101315666B1 - Reducer of Electronic Power Steering Apparatus and Electronic Power Steering Apparatus using The Same

Info

Publication number: KR101315666B1
Application number: KR1020090132730A
Authority: KR
Inventors: 유성재; 표승용
Original assignee: 주식회사 만도
Priority date: 2009-12-29
Filing date: 2009-12-29
Publication date: 2013-10-08
Also published as: KR20110076112A

Abstract

The present invention relates to a speed reducer of an electric power assist steering device and an electric power assist steering device using the same.

In one embodiment of the present invention, the worm is formed in the center and the worm shaft bearings are coupled to both ends to support the rotation of the worm shaft bearing so as to absorb vibration and noise generated by friction and wear during operation of the worm and the worm wheel, the worm shaft bearing A worm shaft having an anti-vibration member on an outer circumferential surface of one side end portion or both end portions to be coupled; A gear housing accommodating the gear mechanism including the worm shaft, the worm shaft bearing, and the worm wheel; And a damper coupled between the opposite end of the motor shaft connection portion of the worm shaft and the gear housing to support the worm shaft in an axial direction. Provide steering device.

According to the present invention, it is possible to reduce rattle noise caused by an increase in backlash due to wear of a worm and a worm wheel, or a rattling noise caused by an impact transmitted through a wheel and a steering shaft from a road surface, Thereby increasing the steering feeling of the vehicle.

Steering, Reducer, Plug Bolt, Plug Nut, Motor

Description

Reducer of electric power assisted steering device and electric power assisted steering device using same {Reducer of Electronic Power Steering Apparatus and Electronic Power Steering Apparatus using The Same}

The present invention relates to a speed reducer of an electric power assisted steering apparatus. More specifically, it reduces rattling noise caused by an increase in backlash caused by wear of a worm and a worm wheel, or a rattle noise caused by an impact transmitted through a wheel and a steering shaft from a road surface, And more particularly, to a reduction gear of an electric power assist steering apparatus and an electric power assist steering apparatus using the same.

1, the electric power assist steering apparatus 100 includes a steering wheel 102 disposed on a driver's seat and a steering shaft 106 connected to the steering wheel 102, A rack pinion mechanism portion 110 including a rack gear and a pinion gear for converting a rotational force inputted from the steering shaft 106 into a linear motion, a tie rod (not shown) at both ends, And a rack bar (112) having a knuckle arm (124).

The steering column 130 is connected to the steering wheel 102 to rotate with the steering wheel 102 and the other side 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 is a cross-sectional view showing a reducer of a conventional electric power assisted steering device. As shown in FIG. 2, the reducer 150 has a worm shaft 254 having a worm 152 formed thereon, and worm shaft bearings at both ends of the worm shaft 254. 257 are respectively installed to support the worm shaft 254, the plug bolt 210 is damped coupler 240 and worm shaft bearing in order to prevent the worm shaft bearing 257 is spaced in the axial direction of the worm shaft 254 257, the plug bolt 210 is fixed by the plug nut 220.

The worm shaft 254 is connected to the motor 146 via a damping coupler 240 so that 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, the reduction gear of the conventional electric power assist steering device has a problem in that manufacturing errors and assembly errors accumulate on the coupling portion of the worm shaft and the motor shaft, causing a bearing jam and increasing rotational resistance of the worm shaft, and also a worm and a worm wheel. When this durability progresses, play occurs due to abrasion, rattle noise occurs due to backlash, and shock caused by the rattle noise caused by the impact transmitted through the wheels and the steering shaft from the road surface to cause discomfort to the driver when operating the steering wheel. There was this.

Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to reduce the rattle noise caused by an increase in backlash caused by wear of a worm and a worm wheel, The purpose of the present invention is to increase the sense of driver's steering by reducing the sense of hanging and turning resistance of the worm shaft bearing.

In order to achieve the above object, an embodiment of the present invention includes a worm shaft bearing having a worm formed at its center and supporting rotation at both ends thereof so as to absorb vibration and noise generated by friction and wear during operation of the worm and the worm wheel. A worm shaft coupled to the outer circumferential surface of one end or both ends to which the worm shaft bearing is coupled; A gear housing accommodating the gear mechanism including the worm shaft, the worm shaft bearing, and the worm wheel; And a damper coupled between the opposite end of the motor shaft connection portion of the worm shaft and the gear housing to support the worm shaft in an axial direction.

In addition, an embodiment of the present invention, in the electric power assist steering device for assisting the steering force of the steering wheel via the reducer and the motor, the reducer, vibration and noise generated by friction and wear during operation of the worm and worm wheel The worm shaft has a worm formed therein, and a worm shaft bearing for supporting rotation at both ends thereof is coupled to the center thereof, and a dustproof member is provided at an outer circumferential surface of one end or both ends to which the worm shaft bearing is coupled; A gear housing accommodating the gear mechanism including the worm shaft, the worm shaft bearing, and the worm wheel; And a damper coupled between the opposite end of the motor shaft connection portion of the worm shaft and the gear housing to support the worm shaft in an axial direction.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though 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 addition, in describing the component of this invention, terms, such as 1st, 2nd, A, B, (a), (b), can 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 is a cross-sectional view showing a reducer of the electric power assisted steering apparatus according to the first embodiment of the present invention, and FIG. 4 is a cross-sectional view showing a reducer of the electric power assisted steering apparatus according to the second embodiment of the present invention. FIG. 6 is an exploded perspective view illustrating the damper and the damper housing of FIG. 4, and FIG. 7 is a graph illustrating damping characteristics of the reducer according to embodiments of the present disclosure.

First, as shown in FIG. 3, the speed reducer of the electric power assisted steering apparatus according to the first embodiment of the present invention is configured to absorb vibrations and noises generated by friction and wear during operation of the worm 152 and the worm wheel 156. In the center, the worm 152 is formed and a worm shaft bearing 257 for supporting rotation is coupled to both ends thereof, and a dustproof member 320 is provided at an outer circumferential surface of one end or both ends to which the worm shaft bearing 257 is coupled. A worm shaft 254 formed therein; A gear housing 260 accommodating a gear mechanism including the worm shaft 254, the worm shaft bearing 257, and the worm wheel 156; And a damper 330 coupled between the opposite end of the motor shaft 305 connecting portion of the worm shaft 254 and the gear housing 260 to support the worm shaft 254 in the axial direction.

In addition, the reducer according to the second embodiment of the present invention shown in Figure 4 is wrapped around the outer surface of the damper 330 is inserted into the damper housing (343) coupled to the inside of the gear housing (260); A housing fixing member 350 which forms a recess in the inner surface of the gear housing 260 to prevent the damper housing 343 from being separated and is coupled thereto to support the damper housing 343; And a damper fixing member 351 which forms a recess in the inner surface of the gear housing 260 and is coupled thereto to support the damper 330 to prevent the damper 330 from being separated. .

The worm shaft bearing 257 coupled to the end portion of the worm shaft 254 and the opposite end thereof at the portion connected to the motor shaft 305 has a ball coupled between the inner ring and the outer ring to support rotation of the worm shaft 254.

The reducer assists the driver's steering force by rotating the steering shaft 106 while the worm 152 and the worm wheel 156 are interlocked by the driving force of the motor 146. The motor shaft 305 is driven when the motor 146 is driven. The worm shaft bearing 257 is fastened to both ends of the worm shaft 254 interlocked with each other to support rotation of the worm shaft 254. The worm wheel 156 and the worm 152 interlocked with the steering shaft 105 are gear housings ( 260).

The worm shaft bearing 257 is mounted inside the gear housing 260 and supports the rotation of the worm shaft 254 at both ends of the worm shaft 254 and reduces the rotational resistance of the worm shaft 254. The worm shaft 254 and the motor shaft 305 is a coupling portion between the shaft and the shaft via the motor boss and the plug bolt 210, the manufacturing error and the assembly error accumulates, so that the amount of engagement of the bearing is increased, which causes the worm shaft 254 Rotational resistance is increased.

In addition, when the external force transmitted from the road surface through the wheel and the steering shaft 106 is transmitted to the worm wheel 156, the worm shaft 254 engaged with the worm wheel 156 as well as the axial direction is twisted at a predetermined angle with the axial direction. It causes elastic deformation.

Therefore, the external force transmitted through the worm wheel 156, and the vibration caused by the elastic deformation of the worm shaft 254 in the axial direction or the axial direction and a predetermined angle by the operation of the worm 152 and the worm wheel 156 One end or both ends of the worm shaft 254 to which the damper 330 is coupled to the opposite end of the coupling portion of the motor shaft 305 of the both ends of the worm shaft 254 to absorb noise and noise. The outer circumferential surface of the dustproof member 320 is provided.

Damper 330 is coupled between the inner surface of the gear housing 260 and the end of the worm shaft 254 in a hollow shape to absorb the vibration and noise transmitted through the worm shaft 254, such a damper 330 is supported The inner surface of the gear housing 260 is provided with a locking portion 310 protruding in the axial direction so that it can be fixed, one side of the damper 330 is inserted and fixed to the locking portion 310 and the damper 330 The other side of the worm shaft 254 is inserted into and fixed to the opposite end of the motor shaft 305 connecting portion.

Accordingly, both sides of the damper 330 are supported by the gear housing 260 and the worm shaft 254 to absorb vibrations and noises transmitted through the worm shaft 254 while elastically deforming and expanding.

In addition, the anti-vibration member 320 provided at one end or both ends of the worm shaft 254 to which the worm shaft bearing 257 is coupled is the end portion of the worm shaft 254 made of any one or more of a dustproof material such as Teflon, silicone, urethane, and rubber. The coating is formed on the outer circumferential surface thereof to absorb vibrations and noises transmitted through the worm shaft 254.

Such a reducer may further include a damper housing 343, a housing fixing member 350, a damper fixing member 351, and the like as the second embodiment of the present invention illustrated in FIG. 4.

The damper housing 343 is inserted to surround the outer surface of the damper 330 and is coupled to the inside of the gear housing 260, and the housing fixing member 350 and the damper 330 to prevent the damper housing 343 from being separated. Damper fixing member 351 to prevent the separation is coupled to the inner surface of the gear housing 260 in the damper housing 343 and the damper 330, respectively.

That is, the housing fixing member 350 and the damper fixing member 351 are coupled to grooves formed in the gear housing 260 on both sides of the damper housing 343, respectively, in which the damper 330 is inserted into the damper housing 343. 343 and the damper 330 are no longer elastic deformation away from the axial direction on the worm shaft 254, but only close to the elastic deformation.

Here, the fixing members 350 and 351 are formed in an annular shape with one side cut, and a snap ring or washer coupled to the groove of the gear housing 260 may be used with a radial elastic force.

In addition, the damper 330 may include a damper support having a large diameter portion 333 supported by the damper fixing member 351 and a small diameter portion 335 having a reduced diameter formed from the large diameter portion 333, and the small diameter portion 335. And an elastic body 340 inserted into the damper support member and providing the elastic force between the damper housing 343 and one or more damping protrusions protruding toward the damper housing 343. 345.

Here, the damping protrusion 345 may protrude toward the damper housing 343 to have a circumferential shape. By providing the damping protrusion 345, the damping protrusion 345 may absorb vibrations and noises transmitted at various sizes.

That is, when the load transmitted is small, the load is supported by the elastic force of the damping protrusion 345, and when a large load is momentarily transferred, the damping protrusion 345 and the elastic body 340 simultaneously support the load, thereby causing rattle noise. It is to prevent.

This shows a load-displacement curve in which the displacement of the damping protrusion 345 increases to approximately S ₁ until the load transmitted as shown in FIG. 7 is approximately F _1, but the entire elastic body 340 is transmitted when a large load out of this is transmitted. The damping characteristic is shown to absorb the load and increase the load-displacement curve rapidly.

Therefore, even if the external force transmitted through the steering shaft and the worm wheel on the road surface and the load generated during the operation of the worm and the worm wheel are transmitted in various forms having a range of small value to large value, various types of rattles can be generated in the reducer by absorbing it It will reduce the noise.

Here, the damper 330 or the elastic body 340 is required to be formed of a material having a predetermined bending and rigidity as well as low elasticity by heat, as well as wear resistance and low friction, polyacetal (POM), polyamide (PA) , Polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), etc., or formed of engineering plastics such as natural rubber (NR (Natural Rubber), NBR (Nitrile) to have weatherability and elasticity Butadiene Rubber (CR), Chloroprene Rubber (CR), Ethylene Propylene Terpolymer (EPDM), Fluoro Elastomer (FPM), Styrene Butadine Rubber (SBR), Chrorosulphonated Polyethylene (CSM), Silicon, etc.

On the other hand, the reducer according to the embodiments of the present invention, referring to Figure 1 together in the electric power assist steering device for assisting the steering force of the steering wheel via the reducer and the motor 146, connected to the steering wheel A rack pinion mechanism part including a steering shaft 106, a steering column (see 130 in FIG. 1) for fixing the steering shaft to a vehicle body, and a rack gear and pinion gear for converting rotational force input from the steering shaft into linear motion ( 1), and a rack bar (see 112 of FIG. 1) having tie rods and knuckle arms at both ends thereof constitute an electric power assist steering device.

According to the embodiments of the present invention having such a shape and structure, it is possible to reduce the rattle noise caused by the increase of backlash due to the wear of the worm and the worm wheel, or the rattling noise caused by the impact transmitted from the road surface through the wheel and the steering shaft, It is possible to reduce the hung feeling and rotational resistance of the worm shaft bearing, thereby increasing the steering feeling of the driver.

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. In other words, within the scope of the present invention, all of the components may be selectively operated in combination with one or more.

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.

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. It is to be understood, however, that the present invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a block diagram of a conventional electric power assisted steering device;

2 is a cross-sectional view showing a reducer of a conventional electric power assisted steering device;

3 is a cross-sectional view showing a reducer of the electric power assisted steering apparatus according to the first embodiment of the present invention;

4 is a cross-sectional view showing a reducer of the electric power assisted steering apparatus according to the second embodiment of the present invention;

5 and 6 are exploded perspective views showing the damper and damper housing of FIG.

7 is a graph showing the damping characteristics of the reducer according to embodiments of the present invention.

247: worm shaft bearing 310: engaging portion

320: dustproof member 330: damper

333: large neck 335: small neck

340: elastomer 343: damper housing

345: damping protrusion 350: housing fixing member

Claims

To absorb vibrations and noise caused by friction and wear during operation of the worm and worm wheel,

A worm shaft having a worm formed therein and a worm shaft bearing supporting rotation at both ends thereof, and having a dustproof member at an outer circumferential surface of one end or both ends to which the worm shaft bearing is coupled;

A gear housing accommodating the gear mechanism including the worm shaft, the worm shaft bearing, and the worm wheel;

A damper coupled between the opposite end of the motor shaft connection portion of the worm shaft and the gear housing to support the worm shaft in an axial direction;

A damper housing wrapped around an outer surface of the damper and coupled to an inner side of the gear housing;

A housing fixing member which forms a recess in the inner side of the gear housing and is coupled thereto to support the damper housing to prevent the damper housing from being separated; And

A damper fixing member forming a recess in the inner side of the gear housing and preventing the damper from being separated from the damper, and supporting the damper;

Reducer of the electric power assisted steering device, characterized in that it comprises a.

The method of claim 1,

The inner side of the gear housing is provided with a locking portion protruding in the axial direction, the damper is formed in a hollow shape is an electric power assist characterized in that is inserted into and supported opposite the motor shaft connecting portion of the locking portion and the worm shaft. Reducer of the steering system.

The method of claim 1,

The anti-vibration member is a reducer of the electric power assist steering device, characterized in that the coating is formed on the outer circumferential surface of the worm shaft end of any one or more of Teflon, silicon, urethane, rubber.

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The method of claim 1,

The damper includes a damper support having a large diameter portion supported by the damper fixing member and a small diameter portion reduced in diameter from the large diameter portion, and inserted into the small diameter portion to provide an elastic force between the damper support and the damper housing. Reducer of the electric power assisted steering apparatus, characterized in that formed of an elastic body to provide.

6. The method of claim 5,

The elastic body is a reducer of the electric power assist steering device, characterized in that provided with one or more damping projections protruding toward the damper housing.

6. The method of claim 5,

And the elastic body has one or more damping protrusions protruding toward the damper housing and formed in a circumferential shape.

In the electric power assist steering device for assisting the steering force of the steering wheel through the reducer and the motor,

The speed reducer includes:

Electric power assisted steering, characterized in that it comprises a.

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9. The method of claim 8,

The damper includes a damper support having a large diameter portion supported by the damper fixing member and a small diameter portion reduced in diameter from the large diameter portion, and inserted into the small diameter portion to provide an elastic force between the damper support and the damper housing. The electric power assisted steering device, characterized in that formed of an elastic body to provide.

11. The method of claim 10,

The elastic body is an electric power assisted steering device, characterized in that provided with one or more damping projections protruding toward the damper housing.

11. The method of claim 10,

And the elastic body is provided with at least one damping protrusion protruding toward the damper housing and formed in a circumferential shape.