KR20120140303A - Reducer of electric power steering apparatus and electric power steering apparatus using the same - Google Patents

Abstract

The present invention relates to a speed reducer of an electric power assisted steering device and an electric power assisted steering device having the same. According to the present invention, an increase in backlash caused by abrasion of a worm and a worm wheel is generated or transmitted from a road surface through a wheel and a steering shaft. The rattle noise generated by the impact is reduced, and the grip and rotational resistance of the worm shaft and the worm shaft bearing are reduced to increase the driver's steering feeling.

Description

Reducer of electric power assisted steering device and electric power assisted steering device having same {Reducer of Electric Power Steering Apparatus and Electric 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 rattle noise caused by an increase in backlash due to wear of worms and worm wheels, or an impact transmitted from a road surface through wheels and steering shafts, and reduces the grip and rotational resistance of 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 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, 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, The worm shaft 257 is installed to support the worm shaft 254 and the plug bolt 210 is fixed to the damping coupler 240 and the worm shaft bearing 254 in order to prevent the worm shaft 257 from being spaced in the axial direction of the worm shaft 254. [ 257, and 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.

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 reducer of the conventional electric power assisted steering device is transmitted to the steering shaft in addition to the rotational force of the steering wheel operated by the driver in response to the driving conditions of the worm shaft driven by the motor provided in the vehicle, thereby driving the driver's steering operation. This is to keep the state 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 the backlash due to the wear of the worm and 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 bearing.

In order to achieve the above object, an embodiment of the present invention includes a worm shaft in which a worm is formed, a worm wheel in which a worm gear part engaged with the worm is formed, and a gear housing coupled to an end of the worm shaft or a worm shaft bearing coupled thereto. It provides a reducer of the electric power assist steering device characterized in that it comprises a worm shaft support for supporting in the worm wheel direction.

In addition, another 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, the worm shaft is formed with a worm, and the worm gear meshed with the worm And an worm shaft support coupled to the worm wheel having an additional portion and a worm shaft bearing coupled to the gear housing to support the end of the worm shaft or the worm shaft bearing coupled thereto in the worm wheel direction.

Here, the worm shaft support, a pin housing coupled to the gear housing, a push pin inserted into the pin housing to support the end of the worm shaft or a worm shaft bearing, and the push pin is inserted into the pin housing in the worm wheel direction And a first elastic body coupled between the push pin and the guide pin to provide an elastic force, and a second elastic body coupled between the pin housing and the guide pin to provide an elastic force. Is coupled to the upper side may further include an adjustment plug for adjusting the elastic force of the second elastic body.

According to the present invention, reducing 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, reducing the grip and rotational resistance of the worm shaft and worm shaft bearing This reduces the driver's steering feel.

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 an embodiment of the present invention;
4 is a cross-sectional view showing a reducer of the electric power assisted steering apparatus according to another embodiment of the present invention;
5 is an exploded perspective view showing the worm shaft support of Figure 4;
6 is a sectional view showing a modified embodiment of FIG. 4;
7 is a graph showing the relationship between the load and the displacement of the worm shaft support.

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 an embodiment of the present invention, Figure 4 is a cross-sectional view showing a reducer of the electric power assisted steering apparatus according to another embodiment of the present invention, Figure 5 4 is an exploded perspective view showing a worm shaft support of Figure 4, Figure 6 is a cross-sectional view showing a modified embodiment of Figure 4, Figure 7 is a graph showing the load and displacement relationship of the worm shaft support.

As shown in these drawings, the speed reducer 300 of the electric power assisted steering apparatus according to the embodiment of the present invention includes a worm shaft 254 in which a worm 152 is formed, and a worm gear engaged with the worm 152. The worm shaft support body which is coupled to the worm wheel 156 and the gear housing 260, which is formed with a portion 156a, and supports the end of the worm shaft 254 or the worm shaft bearing 257 coupled thereto in the direction of the worm wheel 156. 310 is configured to include.

Here, the worm shaft support 310 is inserted into the pin housing 311 and the pin housing 311 is coupled to the gear housing 260 to support the end or worm shaft bearing 257 of the worm shaft 254 A push pin 313 and a guide pin 317 inserted into the pin housing 311 to support the push pin 313 in the direction of the worm wheel 156 with an elastic force, and the push pin 313 and the guide pin ( The first elastic body 315 is coupled between the 317 to provide an elastic force, and the second elastic body 319 is coupled between the pin housing 311 and the guide pin 317 to provide an elastic force.

In addition, the worm shaft support 310 may further include an adjustment plug 320 coupled to the upper side of the pin housing 311 to adjust the elastic force of the second elastic body 319.

3 to 7 together with reference to FIG. 1, the reducer 300 rotates the steering shaft 106 while the worm 152 and the worm wheel 156 are driven by the driving force of the motor 146 to rotate the steering force of the driver. The worm shaft bearing 257 is fastened to both ends of the worm shaft 254 which is interlocked with the motor shaft when the motor 146 is driven to support rotation of the worm shaft 254, and is interlocked with the steering shaft 106. The worm wheel 156 and the worm 152 are embedded in the gear housing 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. When the external force transmitted through the 106 is transmitted to the worm wheel 156, not only the axial direction but also the worm shaft 254 engaged with the worm wheel 156 causes elastic deformation that is twisted at a predetermined angle with the axial direction.

In addition, if the durability is to some extent, the play is increased due to the wear of the worm 152 and the worm wheel 156, the noise is generated and the transmission of the correct steering assistance is not made.

Therefore, when the clearance between the worm shaft 254 and the worm wheel 156 occurs, the clearance is absorbed by the bearing force of the worm shaft support 310 which is supported and coupled to the gear housing 260.

The worm shaft support 310 may include a pin housing 311 that is press-fitted or screwed into the gear housing 260, a push pin 313, a guide pin 317, and a first elastic body embedded inside the pin housing 311. 315, a second elastic body 319, and the like, and may include an adjusting plug 320 in some cases.

The push pin 313 is inserted into the pin housing 311 to support the end of the worm shaft 254 or the worm shaft bearing 257 and is formed of a large diameter portion 313a and a small diameter portion 313b, which are large diameter portions 313a. ) Is supported on the inner circumferential surface of the pin housing 311 and slides to support the first elastic body 315 and the guide pin 317 on the upper side.

The small diameter portion 313b protruding downward of the large diameter portion 313a supports the end of the worm shaft 254 or the worm shaft bearing 257, and is provided at the end of the worm shaft 254 or the end supporting the worm shaft bearing 257. The damping member 312 is provided to prevent noise caused by contact with the worm shaft 254 or the worm shaft bearing 257 when a shock inputted from the road surface is transmitted.

The damping member 312 may be formed of a plastic or rubber material and may be fused, bonded, or integrally molded at the end of the push pin 313.

The guide pin 317 is inserted into the pin housing 311 to support the push pin 313 in the direction of the worm wheel 156 with elastic force. Similarly to the push pin 313, the large diameter portion 317a and the small diameter portion 317b. Is formed.

The large diameter portion 317a of the guide pin 317 is supported on the inner circumferential surface of the pin housing 311 and slid and supports the second elastic body 319 on the upper side thereof. The protrusion 317c is provided on the upper side thereof to have a disc shape. The second elastic body 319 is not pushed to either side so that an accurate elastic force is generated.

The small diameter portion 317b of the guide pin 317 supports the push pin 313, and the first elastic body 315 is coupled to the outer circumferential side thereof, and the first elastic body 315 includes the push pin 313 and the guide pin ( It is coupled between the 317 to provide an elastic force, the elastic force of the first elastic body 315 is formed smaller than the second elastic body 319.

That is, as shown in FIG. 7, the elastic modulus A of the first elastic body 315 is smaller than the elastic modulus B of the second elastic body 319 in the graph of the load P and the displacement X. When the worm gear part 156a wears due to friction with the 152 and a play occurs, the push pin 313 moves the end of the worm shaft 254 or the worm shaft bearing 257 by the elastic force of the first elastic body 315. 156).

In addition, the second elastic body 319 is coupled between the pin housing 311 and the guide pin 317 to provide an elastic force, which is mainly absorbed when a load larger than the elastic force of the first elastic body 315 is reversed from the road surface. To prevent noise.

As described above, the second elastic body 319 has a disk shape, and a coupling hole 319c into which the protrusion 317c of the guide pin 317 is inserted is formed at the center thereof, and the material is made of NR (Natural Rubber) and NBR (Nitrile). Butadiene Rubber (CR), Chloroprene Rubber (CR), Ethylene Propylene Terpolymer (EPDM), Fluoro Rubber (FPM), Styrene Butadine Rubber (SBR), Chlorosulphonated Polyethylene (CSM), Urethane, Silicone, etc. Can be used.

As described above, when the second elastic body 319 is supported by the pin housing 311 to apply elastic force to the guide pin 317, the upper end of the pin housing 311 is formed in a closed shape, and the push pin 313 or the guide is blocked. For assembling the pin 317 and the like is formed in two separate shapes in the axial direction and then assembled.

On the other hand, in addition to this to adjust the preload of the second elastic body 319, that is, the elastic force during the initial assembly, as shown in Figure 4 the adjustment plug 320 is a pin housing 311 in another embodiment of the present invention It can be coupled to the upper side of.

That is, the adjustment plug 320 is screwed to the pin housing 311 so that the elastic force of the second elastic body 319 can be adjusted so that the elastic force of the second elastic body 319 can be adjusted according to the fastening amount thereof. When the adjustment plug 320 is coupled to the pin housing 311, the upper end of the pin housing 311 may be opened.

In addition, a tool engagement surface 311a is formed on an outer circumferential surface of the pin housing 311 so as to facilitate the pin housing 311 being press-fitted or screwed into the gear housing 260, and an upper side surface of the adjustment plug 320. Edo tool groove 320a is formed to facilitate the screwing of the adjustment plug 320.

In addition, according to the modified embodiment of FIG. 4, between the end of the worm shaft 254 and the worm shaft bearing 257, vibration and noise caused by processing scatter during operation and vibration and noise introduced from the road surface may be detected. Absorbing worm shaft damper 330 may be combined.

The worm shaft damper 330 has a groove in the outer circumferential surface of the worm shaft 254 end or the inner circumferential surface of the worm shaft bearing 257 in a ring shape inserted between the worm shaft 254 and the worm shaft bearing 257.

As such, when the gap between the worm 152 and the worm wheel 156 is compensated for, the load generated during the operation of the worm 152 and the worm wheel 156 is absorbed to reduce rattle noise that may be generated in the reducer 300. In addition, since the engagement force of the worm 152 and the worm wheel 156 is constant, the driving force of the motor is accurately transmitted, so that the steering assistance force of the driver can be accurately controlled.

On the other hand, the reducer 300 according to an embodiment of the present invention as described above, referring to Figure 1 is another of the present invention is an electric power assist steering device for assisting the steering force of the steering wheel via the reducer 300 and the motor. One embodiment will be constructed.

That is, a steering shaft 106 connected to a steering wheel, a steering column 130 for fixing the steering shaft to the vehicle body, and a reducer according to an embodiment of the present invention mounted to the steering column to assist the steering force with the driving force of the motor ( 300, a rack pinion mechanism unit 110 including a rack gear and a pinion gear for converting the rotational force input through the speed reducer 300 into a linear motion, and a rack bar 112 having tie rods and knuckle arms at both ends thereof. And the like, to form an electric power assisted steering device according to another embodiment of the present invention.

Here, since the reducer 300 has been described in detail as described above in an embodiment of the present invention, the following detailed description will be omitted.

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. 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 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.

106: Steering axis 152: Worm
156: Worm wheel 254: Worm shaft
257: Worm shaft bearing 260: Gear housing
300: reducer 310: worm shaft support
311: pin housing 313: push pin
315: first elastic body 317: guide pin
319: second elastic body 320: adjustment plug

Claims (10)

A worm shaft in which a worm is formed;
A worm wheel having a worm gear part engaged with the worm; And
A worm shaft support coupled to a gear housing to support an end of the worm shaft or a worm shaft bearing coupled thereto in a direction of the worm wheel;
Reducer of the electric power assisted steering device, characterized in that it comprises a. The method of claim 1,
The worm shaft support,
A pin housing coupled to the gear housing;
A push pin inserted into the pin housing to support an end of the worm shaft or a worm shaft bearing;
A guide pin inserted into the pin housing to support the push pin in a worm wheel direction with an elastic force;
A first elastic body coupled between the push pin and the guide pin to provide an elastic force;
A second elastic body coupled between the pin housing and the guide pin to provide an elastic force;
Reducer of the electric power assisted steering device, characterized in that it comprises a. The method of claim 2,
The worm shaft support is coupled to the upper side of the pin housing reducer of the electric power assist steering device characterized in that it comprises an adjustment plug for adjusting the elastic force of the second elastic body. The method of claim 3, wherein
The control plug is screwed to the pin housing to reduce the speed of the electric power assist steering device, characterized in that for adjusting the elastic force of the second elastic body in accordance with the amount of fastening. The method of claim 2,
The push pin is a reduction gear of the electric power assist steering device, characterized in that the damping member is provided at the end of the worm shaft or the end for supporting the worm shaft bearing. The method of claim 1,
Reducer of the electric power assist steering device characterized in that the worm shaft damper is coupled between the end of the worm shaft and the worm shaft bearing to absorb vibration and noise during operation. The method according to claim 6,
The worm shaft damper is a reducer of the electric power assist steering device characterized in that a groove is provided on the outer circumferential surface of the worm shaft or the inner circumferential surface of the worm shaft bearing in a ring shape inserted between the worm shaft and the worm shaft bearing. An electric power assist steering apparatus for assisting a steering force of a steering wheel via a speed reducer and a motor,
The reducer,
A worm shaft in which a worm is formed;
A worm wheel having a worm gear part engaged with the worm; And
A worm shaft support coupled to a gear housing to support an end of the worm shaft or a worm shaft bearing coupled thereto in a direction of the worm wheel;
Electric power assisted steering, characterized in that it comprises a. The method of claim 8,
The worm shaft support,
A pin housing coupled to the gear housing;
A push pin inserted into the pin housing to support an end of the worm shaft or a worm shaft bearing;
A guide pin inserted into the pin housing to support the push pin in a worm wheel direction with an elastic force;
A first elastic body coupled between the push pin and the guide pin to provide an elastic force;
A second elastic body coupled between the pin housing and the guide pin to provide an elastic force;
Electric power assisted steering, characterized in that it comprises a. The method of claim 9,
The worm shaft support is an electric power assisted steering device, characterized in that it comprises an adjustment plug coupled to the pin housing for adjusting the elastic force of the second elastic body.

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