KR20110073001A - Reducer of electronic power steering apparatus and electronic power steering apparatus using the same - Google Patents

Abstract

PURPOSE: A reducer of electric-powered power auxiliary steering system is provided to reduce rattle noise which is generated from the impact delivered from a road surface through a wheel and steering wheel. CONSTITUTION: A reducer of electric-powered power auxiliary steering system comprises worm shaft bearings(257a,257b), a thrust bearing(340), a damper(330), and a control plug(310). The worm shaft bearing is combined with both end part of the worm shaft in the opposite side of the motor shaft connection part. The worm shaft bearing supports the rotation of the worm shaft. The thrust bearing is combined in the outside of the worm shaft bearing in an axial direction. The thrust bearing supports the axial direction load and the rotation of the worm shaft. The control plug is combined with the damper through one side of the gear housing in order to control the supporting force of the damper.

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 device. More specifically, it reduces rattle noise caused by an increase in backlash due to wear of worms and worm wheels, or an impact transmitted from the road surface through the wheels and steering shafts, and reduces the grip and rotational resistance of the worm shafts and worm shaft bearings. The present invention relates to a speed reducer of an electric power assist steering device for increasing a steering feeling of an electric power assist steering device and an electric power assist steering device using the same.

1 is a configuration diagram of a conventional electric power assisted steering device, as shown in FIG. 1, the electric power assisted steering device 100 includes a steering wheel 102 disposed in a driver's seat and a steering shaft 106 connected thereto, and A steering column 130 for fixing the steering shaft to the vehicle body, a rack pinion mechanism unit 110 including a rack gear and a pinion gear for converting rotational force input from the steering shaft 106 into linear motion, and tie rods at both ends thereof. And a rack bar 112 having a knuckle arm 124.

The steering column 130 has a steering shaft 106 connected to the steering wheel 102 to rotate together with the steering wheel 102 and the other side is connected to the pinion shaft 108 via a pair of universal joints 104. . In addition, the pinion shaft 108 is connected to the rack bar 112 through the rack pinion mechanism unit 110, both ends of the rack bar 112 through the tie rods 122 and the knuckle arm 124 of the vehicle wheel 126 Is connected to.

The auxiliary power mechanism 140 senses torque applied to the steering wheel 102 by the driver and outputs an electrical signal proportional to the detected torque based on the electrical signal transmitted from the torque sensor 142 and the torque sensor 142. The steering shaft 106 controls the electronic control device 144 that generates the control signal, the motor 146 that generates auxiliary power based on the control signal transmitted from the electronic control device 144, and the auxiliary power generated by the motor 146. It comprises a reducer 150 having a worm 152 and a worm wheel 156 for delivery to.

Accordingly, in the electric power assist steering device, 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 assist power generated in the motor 146 is generated according to the generated torque. It is configured to be delivered 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 has a structure in which the worm shaft 254 is rotated by the driving of the motor 146 by connecting the motor 146 and the damping coupler 240 as a medium.

And the worm wheel 156 is provided on one side of the outer diameter of the worm 152 so that the worm 152 formed on the worm shaft 254, the worm wheel 156 is a steering wheel (102 in FIG. And a rotational force of the worm shaft 254 driven by the driving of the motor 146 is transmitted to the steering shaft 106.

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

The speed reducer of the electric power assisted steering device having such a structure controls the driving of the motor by an electronic control device provided in the vehicle according to the vehicle driving conditions, and the rotational force of the worm shaft by the driving of the motor controls the steering wheel of the driver. In addition to the rotational force is transmitted to the steering shaft, so that the steering operation state of the driver can be kept smooth and stable.

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-described problems, reducing the rattle noise caused by the increase in backlash due to friction and wear of the worm and the worm wheel, or the impact transmitted through the wheel and the steering shaft from the road surface, The purpose is to increase the steering feeling of the driver by reducing the grip and rotational resistance of the worm shaft and worm shaft bearings.

In order to achieve this object, one embodiment of the present invention, the opposite side of the motor shaft connecting portion of the both ends of the worm shaft to absorb the vibration and noise generated when the worm shaft is twisted in the axial direction or the axial direction and a predetermined angle. A worm shaft bearing coupled to an end to support rotation of the worm shaft; A thrust bearing coupled to an outer side of the worm shaft bearing to support an axial load and rotation of the worm shaft; A damper coupled to the outer side of the thrust bearing to provide an elastic force in an axial direction; And an adjustment plug coupled to one side of the gear housing so as to support the damper in the axial direction and to adjust the support force of the damper.

In addition, an embodiment of the present invention, in the electric power assisted steering apparatus for assisting the steering force of the steering wheel via the reducer and the motor, the reducer, the worm shaft elastically twisted in the axial direction or the axial direction and a predetermined angle A worm shaft bearing coupled to opposite ends of the motor shaft connecting portions of both ends of the worm shaft so as to absorb vibration and noise generated during deformation; A thrust bearing coupled to an outer side of the worm shaft bearing to support an axial load and rotation of the worm shaft; A damper coupled to the outer side of the thrust bearing to provide an axial force; And an adjustment plug coupled to one side of the gear housing so as to support the damper in the axial direction and to adjust the support force of the damper.

According to the present invention, the rattle noise caused by the increase in backlash due to the friction and wear of the worm and the worm wheel, or the impact transmitted through the wheel and the steering shaft from the road surface is also reduced, and the grip and rotational resistance of the worm shaft and the worm shaft bearing are reduced. This reduces the driver's steering feel.

Hereinafter, some embodiments of the present invention will be described in detail through 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 only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected to or connected to that other component, but another component may be It is to be understood that the components 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, Figure 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.

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 may include vibrations generated when the worm shaft 254 is elastically deformed in an axial direction or a predetermined angle with an axial direction. Worm shaft bearings (257a) coupled to opposite ends of the connection portion of the motor shaft (305) of the both ends of the worm shaft (254) to support the noise to support the rotation of the worm shaft (254); A thrust bearing 340 coupled to an outer side of the worm shaft bearing 257a to support an axial load and rotation of the worm shaft 254; A damper 330 coupled to the outer side of the thrust bearing 340 to provide an elastic force in an axial direction; And an adjustment plug 310 that supports the damper 330 in the axial direction but is coupled through one side of the gear housing 260 to adjust the bearing force of the damper 330.

In addition, the reducer according to the second embodiment of the present invention shown in Figure 4 of the outer ring and the plug bolt 210 of the worm shaft bearing 257b coupled to the end of the motor shaft 305 connecting portion of both ends of the worm shaft 254 It further comprises an elastic ring 320 to provide an elastic force in the axial direction of the worm shaft 254 between the and.

The worm shaft bearings 257a and 257b respectively coupled to the end portions of the worm shaft 254 and the opposite ends thereof coupled to the motor shaft 305 are respectively coupled with balls between the inner and outer rings to support rotation of the worm shaft 254. It is.

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. Worm shaft bearings 257a and 257b are fastened to both ends of the worm shaft 254 interlocked with the worm shaft 254 to support rotation of the worm shaft 254, and the worm wheel 156 and the worm 152 interlocked with the steering shaft 105 are gears. It is embedded in the housing 260.

The worm shaft bearings 257a and 257b are mounted inside the gear housing 260 and support the rotation of the worm shaft 254 at both ends of the worm shaft 254 and reduce the rotational resistance of the worm shaft 254. The part where the motor shaft 305 is coupled is a connection portion between the shaft and the shaft via the motor boss and the plug bolt 210, and manufacturing errors and assembly errors accumulate, thereby increasing the amount of engagement of the bearing, and thus, the worm shaft 254. The rotational resistance of) increases.

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 An elastic ring 320 is coupled to the coupling portion of the motor shaft 305 of the both ends of the worm shaft 254 to absorb noise and noise, and a thrust bearing 340, a damper 330, and an adjustment plug 310 are coupled to opposite ends thereof. ) Is combined.

The thrust bearing 340 coupled to the outer side of the worm shaft bearing 257a coupled to the end of the worm shaft 254 opposite to the coupling portion of the motor shaft 305 supports the rotation of the worm shaft 254 while the worm wheel 156 supports the rotation of the worm shaft 254. It supports the axial load of the worm shaft 254 generated during the operation of the external force or the worm 152 and the worm wheel 156 coming through.

In addition, at the end of the worm shaft 254, a stepped portion 254a is formed between the end of the outer circumferential surface of the worm shaft 254 to which the worm shaft bearing 257a is coupled and the end of the worm shaft 254 is reduced in diameter, thereby providing a thrust bearing ( 340 is axially supported and adapted to engage.

On the other hand, the damper 330 is inserted into the outside of the thrust bearing 340, the adjustment plug 310 for supporting the damper 330 in the axial direction of the worm shaft 254 is pressed or screwed into the gear housing 260. In combination, the adjustment amount of the adjustment plug 310 and the gear housing 260 is adjusted to adjust the compression amount of the damper 330 in the axial direction of the worm shaft 254, that is, the elastic support force.

The adjustment plug 310 supporting the damper 330 in the axial direction is coupled to penetrate through one side of the gear housing 260 and adjusts the elastic support force of the damper 330, that is, the compression amount of the damper 330. It may be forcibly pressed into the gear housing 260, or may be screwed with the gear housing 260 is provided with a screw thread on the outer circumferential surface is formed to be engaged with it.

However, the present invention is not necessarily limited thereto, and in some cases, the gear housing 260 may be coupled to the gear housing 260 by using the lock nut 350 provided with the screw bone on the inner circumferential surface thereof without machining the screw bone on the gear housing 260.

Therefore, by adjusting the elastic support force of the damper 330 through the adjustment plug 310, while supporting the external force transmitted through the worm wheel 156 and the axial load generated during the operation of the worm 152 and the worm wheel 156. The vibration and noise transmitted through the worm shaft 254 is absorbed.

As a result, with the thrust bearing 340 coupled in the axial direction of the worm shaft 254, the damper 330, the adjustment plug 310 is compressed and coupled to generate an axial elastic force to support the axial load.

The damper 330 is formed of a support member 331 positioned at both ends in a hollow shape, and a hollow elastic support 333 coupled between the support members 331, and the damper 330 is a support member. The support member 331 and the elastic support 333 may be integrally formed by injection molding the elastic support 333 in a molten state between the 331.

In addition, between the two ends of the worm shaft 254 to provide an elastic force in the axial direction of the worm shaft 254 between the plug bolt 210 coupled to the end of the connecting portion of the motor shaft 305 and the outer ring of the worm shaft bearing 257b. Elastic ring 320 is coupled.

Here, the elastic ring 320 is formed at one or more protrusion ribs 320a protruding from the outer circumferential surface and extending in the axial direction, and the plug bolt 210 is formed to protrude in the direction of the worm shaft bearing 257 to the elasticity. An elastic ring coupling portion 210a to which the ring 320 is inserted and fixed is formed.

Such an elastic ring 320 is inserted and coupled between the outer ring of the plug bolt 210 and the worm shaft bearing 257 so that the compression amount is preloaded in a state of about 3 to 4 mm so that the elastic force is about 8 to 11 kgf. Therefore, it absorbs the axial load and reduces the rattle noise.

Thus, the elastic ring 320 is coupled to the motor shaft 305 engaging portion of the both ends of the worm shaft 254, and the thrust bearing 340, the damper 330, the adjustment plug 310 and the like are coupled to the opposite end, The external force transmitted through the steering shaft 106 and the worm wheel 156 on the road surface absorbs the load generated during the operation of the worm 152 and the worm wheel 156 to reduce the rattle noise that may be generated in the reducer.

Here, the elastic support 333 and the elastic ring 320 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 ( It is formed of engineering plastics such as PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), etc., or has NR (Natural Rubber), NBR to provide weatherability and elasticity. (Nitrile Butadiene Rubber), CR (Chloroprene Rubber), EPDM (Ethylene Propylene Terpolymer), FPM (Fluoro Elastomer), SBR (Styrene Butadine Rubber), CSM (Chlorosulphonated Polyethylene), etc.

On the other hand, the reducer according to the embodiment of the present invention, in conjunction with Figure 1, in the electric power assist steering device for assisting the steering force of the steering wheel via the reducer and the motor (see 146 of Figure 1), the steering wheel A rack pinion including a steering shaft 106 connected to the steering shaft, a steering column for fixing the steering shaft to the vehicle body (see 130 in FIG. 1), and a rack gear and pinion gear for converting the rotational force input from the steering shaft into linear motion. It is combined with a mechanism part (see 110 in FIG. 1) and a rack bar (see 112 in FIG. 1) provided with tie rods and knuckle arms at both ends to form an electric power assist steering device.

According to the embodiments of the present invention having such a shape and structure, the rattle noise caused by the increase in backlash due to the wear of the worm and the worm wheel, or the impact transmitted through the wheel and the steering shaft from the road surface is also reduced. By reducing the grip and rotational resistance of the worm shaft bearings, the driver's steering feeling is increased.

In the above description, all elements constituting the embodiments of the present invention are described as being combined or operating in combination, but the present invention is not necessarily limited to the 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.

In addition, the terms "comprise", "comprise" or "having" described above mean that the corresponding component may be included, unless otherwise stated, and thus excludes other components. It should be construed that it may further include other components instead.

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 not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. 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.

<Description of the symbols for the main parts of the drawings>

305: motor shaft 310: adjustment plug

320: elastic ring 320a: protrusion rib

330: damper 331: support member

333: elastic support 340: thrust bearing

350: locknut

Claims (10)

To absorb the vibration and noise generated when the worm shaft is elastically twisted in the axial direction or the predetermined angle with the axial direction, A worm shaft bearing coupled to opposite ends of the motor shaft connecting portions of both ends of the worm shaft to support rotation of the worm shaft; A thrust bearing coupled to an outer side of the worm shaft bearing to support an axial load and rotation of the worm shaft; A damper coupled to the outer side of the thrust bearing to provide an elastic force in an axial direction; And An adjustment plug that supports the damper in an axial direction and is coupled through one side of a gear housing so as to adjust a bearing force of the damper; Reducer of the electric power assisted steering device, characterized in that it comprises a. The method of claim 1, Reducer of the electric power assisted steering apparatus, characterized in that the elastic ring for providing an elastic force in the axial direction of the worm shaft is coupled between the outer ring of the worm shaft bearing and the plug bolt coupled to the end of the motor shaft connecting portion of the worm shaft. . The method of claim 2, The plug bolt protrudes in the worm shaft bearing direction, the reducer of the electric power assist steering device, characterized in that the elastic ring coupling portion is formed is inserted into the elastic ring fixed. The method of claim 2, The reducer of the electric power assist steering device characterized in that the elastic ring is formed protruding from the outer circumferential surface is formed at least one projection rib formed long in the axial direction. The method of claim 1, The damper is a reducer of the electric power assist steering device, characterized in that the hollow member is formed of a support member positioned at both ends, and a hollow elastic support body coupled between the support member. The method of claim 5, The damper is injection reduction molding the molten elastic support between the support member, the reducer of the electric power assisted steering apparatus, characterized in that the support member and the elastic support are integrally formed. In the electric power assist steering device for assisting the steering force of the steering wheel through the reducer and the motor, The reducer, To absorb the vibration and noise generated when the worm shaft is elastically twisted in the axial direction or the predetermined angle with the axial direction, A worm shaft bearing coupled to opposite ends of the motor shaft connecting portions of both ends of the worm shaft to support rotation of the worm shaft; A thrust bearing coupled to an outer side of the worm shaft bearing to support an axial load and rotation of the worm shaft; A damper coupled to the outer side of the thrust bearing to provide an elastic force in an axial direction; And An adjustment plug that supports the damper in an axial direction and is coupled through one side of a gear housing so as to adjust a bearing force of the damper; Electric power assisted steering, characterized in that it comprises a. The method of claim 7, wherein And an elastic ring for providing an elastic force in the axial direction of the worm shaft between the outer ring of the worm shaft bearing and the plug bolt coupled to the end of the motor shaft connecting portion of both ends of the worm shaft. The method of claim 8, The elastic ring is an electric power assist steering device, characterized in that one or more protrusion ribs are formed protruding from the outer peripheral surface is formed long in the axial direction. The method of claim 7, wherein The damper is an electric power assisted steering device, characterized in that the hollow member is formed of a support member positioned at both ends and a hollow elastic support coupled between the support member.

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