KR102421439B1 - Reducer of Electric Power Steering Apparatus - Google Patents

Abstract

The present embodiments relate to a speed reducer of an electric power-assisted steering system. The present embodiments relate to a first shaft having at least one protrusion on an outer circumferential surface, and at least one extended end extending in the axial direction at the end. A second shaft, an insertion groove into which the protrusion is inserted, is provided in the center, a first coupling part through which the first shaft is coupled is provided, and a second coupling part is formed on the outer periphery of which the extended end is seated, so that the second shaft is coupled to power transmission Provided is a speed reducer for an electric power assisted steering system including a member.

Description

Reducer of Electric Power Steering Apparatus

The present embodiments relate to a speed reducer of an electric power assisted steering system. More specifically, compared to the conventional power transmission member, the volume is significantly reduced, the number of parts is reduced and the manufacturing process is reduced, and noise caused by vibration and noise during power transmission is eliminated while eliminating the noise caused by the gap between the shaft and the power transmission member. It relates to a speed reducer for an electric power assisted steering system that can be prevented.

A vehicle's steering system is a device that allows the driver to freely change the direction of the vehicle's travel by turning the steering wheel. it's a device In such a steering system, a power-assisted steering system is used as an auxiliary power mechanism to relieve the driver's power. This power-assisted steering system mainly uses the power of the engine to operate a hydraulic pump to assist the steering force. There is a hydraulic power assisted steering system using hydraulic pressure and an electric power assisted steering system using an electric motor.

The hydraulic power assist steering system detects the rotation of the steering wheel, receives rotational force from the engine, operates a hydraulic pump, and sends this hydraulic pressure to a driving unit such as a rack bar or a cylinder configured on the steering shaft to assist the driver's steering force.

The electric power-assisted steering system has a structure that detects the rotation of the steering wheel and operates a motor that is installed on the rack or the steering shaft to help the rotational movement so that the steering system operates smoothly. There is a type (R-EPS) and a steering shaft driven type (C-EPS).

1 is a schematic view of a conventional electric power assist steering system.

As shown in FIG. 1 , the electric power assist steering device is an auxiliary power mechanism 120 that provides steering assistance power to the steering system 100 and the steering system 100 that extend from the steering wheel 101 to both wheels 108 . is comprised of

The steering system 100 has one side connected to the steering wheel 101 to rotate together with the steering wheel 101 and the other side is a steering shaft 102 connected to the pinion shaft 104 via a pair of universal joints 103 as a medium. ) is included. In addition, the pinion shaft 104 is connected to the rack bar through the rack-and-pinion mechanism 105 , and both ends of the rack bar are connected to the wheel 108 of the vehicle through the tie rod 106 and the knuckle arm 107 . The rack-and-pinion mechanism part 105 is formed by meshing the pinion gear 111 formed on the pinion shaft 104 and the rack gear 112 formed on one outer circumferential side of the rack bar, so that the driver operates the steering wheel 101 . When the torque is generated in the steering system 100, the wheel 108 is steered through the rack-and-pinion mechanism 105 and the tie rod 106 by the torque.

The auxiliary power mechanism 120 detects the torque applied by the driver to the steering wheel 101 and outputs an electric signal proportional to the sensed torque. A control signal based on an electric signal transmitted from the torque sensor 125 and the torque sensor. An electronic control unit 123 that generates 140) is included.

2 is a cross-sectional view showing a reducer of a conventional electric power assist steering device.

As shown in FIG. 2 , the reducer of the electric power assist steering device includes a motor 130 , a drive shaft 205 , an inner rotor 220 , an outer rotor 215 , an elastic body 210 , a first bearing 250 , and a worm shaft. 235 , a worm gear 245 , a second bearing 270 , a compression screw 255 , a compression spring 265 , and a gear housing 260 .

The motor 130 has a drive shaft 205 extending outside the motor housing, and the outer rotor 215 has a hollow inside and one side is connected to the drive shaft 215 and interlocks. The second bearing 270 and the first bearing 250 fix the worm gear 245 toward the worm wheel gear 240 installed on the steering shaft. The compression spring 265 supports the worm gear 245 in the direction of the worm wheel gear 240 by the compression screw 255 and supports the second bearing 270 . Therefore, when the compression screw 255 is tightened, the compression screw 255 moves and the compression spring 265 contracts. to be able to bite

The inner rotor 220 is connected to the worm shaft 235 , and the inner rotor 220 has a structure in which one side is inserted into the outer rotor 215 connected to the driving shaft 205 .

However, since the reducer of the conventional electric power-assisted steering device has a structure in which an inner rotor and an outer rotor are press-fitted and coupled, there is a problem in that the volume is large, the number of parts is increased, and the manufacturing process is increased.

In addition, there is a problem in that vibration and noise due to contact are generated when a large impact is reversely inputted along the steering shaft when the durability is progressed to a certain extent or when driving on a road such as off-road.

In addition, since an assembly process of the inner rotor and the outer rotor and a process of applying grease therebetween are required, there is a problem in that the assembly process is increased and the cost is increased.

Accordingly, the present embodiments have been devised in the background described above, and compared with the conventional power transmission member, the volume is greatly reduced, the number of parts is reduced and the manufacturing process is reduced, and the power transmission is performed while eliminating the noise caused by the gap between the shaft and the power transmission member. An object of the present invention is to provide a reducer of an electric power assist steering system capable of preventing noise caused by vibration and noise.

In addition, the purpose of the present embodiments is not limited thereto, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve this object, the present embodiments provide a first shaft having at least one protrusion on the outer circumferential surface, a second shaft having at least one extended end extending in the axial direction at the end, and a protrusion inserted into the center An electric power-assisted steering device comprising a power transmission member having an insertion groove which becomes an insertion groove, a first coupling part through which the first shaft is coupled, and a second coupling part having an extended end seated thereon is formed on the outer periphery side to be coupled to the second shaft. of reducer is provided.

According to the present embodiments having such a structure and shape, there is an effect that the volume is greatly reduced, the number of parts is reduced and the manufacturing process is reduced compared to the conventional structure in which the inner rotor and the outer rotor are press-fitted and coupled.

In addition, according to the present embodiments, compared to the conventional power transmission member, it is possible to eliminate noise due to the clearance between the shaft and the power transmission member, and noise caused by vibration and noise when power is transmitted at the portion where the two shafts are coupled. has the effect of being able to prevent

1 is a schematic view of a conventional electric power assisted steering system;
2 is a cross-sectional view showing a reducer of a conventional electric power assist steering device;
3 is an exploded perspective view showing the reducer of the electric power assist steering device according to the present embodiments;
4 is a perspective view showing a part of the reducer of the electric power assist steering system according to the present embodiments;
5 and 6 are cross-sectional views showing the reducer of the electric power assist steering apparatus according to the present embodiments.

Hereinafter, the present embodiments 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 components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in the description of the present embodiments, if it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present embodiments, the detailed description thereof will be omitted.

Also, in describing the components of the present embodiments, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but another component is between each component. It should be understood that elements may be “connected,” “coupled,” or “connected.”

3 is an exploded perspective view showing the reducer of the electric power-assisted steering system according to the present embodiments, FIG. 4 is a perspective view showing a part of the reducer of the electric power-assisted steering system according to the present embodiments, and FIGS. 5 and 6 are views It is a cross-sectional view showing the reducer of the electric power assist steering system according to the embodiments.

As shown in these drawings, the reducer of the electric power-assisted steering device according to the present embodiments is a first shaft 310 having at least one protrusion 311 on an outer circumferential surface, the end portion extending in the axial direction. The second shaft 320 having at least one extended end 321 is provided, the insertion groove 333 into which the protrusion 311 is inserted is provided in the center, and the first coupling part to which the first shaft 310 is coupled through. (335) is provided and the second coupling part 331 on which the extended end part 321 is seated is formed on the outer peripheral side, and includes a power transmission member 330 to which the second shaft 320 is coupled.

The power transmission member 330 is connected to a power source such as a motor 130 and a pump and is coaxially connected to the rotating first shaft 310 to transmit a driving force from the power source to the second shaft 320 , in this embodiment In their detailed description, the first shaft 310 is a motor shaft, and the second shaft 320 is a speed reducer of the electric power-assisted steering system consisting of a worm shaft will be described as an example.

And, in this case, the power transmission member 330 connects the motor shaft that generates the auxiliary power of the electric power assist steering device and the worm shaft, and transmits the auxiliary power generated from the motor to the steering shaft coupled to the worm wheel. It is used as a power linkage to assist the steering force.

The power transmission member 330 coaxially connects the first shaft 310 and the second shaft 320 and transmits power to the first shaft 310 and the second shaft 320 on the central and outer peripheral surfaces, respectively. ) overlapped inside and outside and are combined.

The first shaft 310 is provided with at least one protrusion 311 on the outer circumferential surface, and the second shaft 320 is provided with at least one extended end 321 extending in the axial direction at the end of the power transmission member. (330) is combined.

The power transmission member 330 is provided with a first coupling portion 335 to which the first shaft 310 is coupled through the central portion, and the protrusion 311 of the first shaft 310 is provided on the inner circumferential surface of the first coupling portion 335 . ) is provided with an insertion groove 333 into which it is inserted.

And, a second coupling part 331 on which the extended end 321 of the second shaft 320 is seated is formed on the outer periphery of the power transmission member 330 so that the second shaft 320 is connected to the power transmission member 330 . coupled to the outer periphery.

Accordingly, compared to the conventional structure in which the inner rotor and the outer rotor are press-fitted and coupled, the volume is greatly reduced, the number of parts is reduced, and the manufacturing process is reduced.

In addition, when two or more protrusions 311 are provided, the protrusions 311 and the insertion grooves 333 are spaced apart from each other at equal intervals in the circumferential direction of the first shaft 310, so that when rotating when power is transmitted, the protrusion 311 and the insertion groove 333 are biased toward either side. It can rotate evenly without hitting.

In addition, the extended end 321 of the second shaft 320 may be provided in the same number as the protrusion 311 of the first shaft 310 , where the position of the extended end 321 is in the circumferential direction of the protrusion 311 . formed to be disposed between.

In addition, the extended end 321 of the second shaft 320 is disposed at the same interval as the protrusion 311 on both sides in the circumferential direction, so that a rotational load is uniformly applied during power transmission and vibration can be minimized.

The power transmission member 330 may include a damping member 337 formed in the center and support members 339a and 339b provided at both ends of the damping member 337 , respectively.

The damping member 337 is provided with a first coupling part 335 and a second coupling part 331 on the center and the outer circumferential surface, respectively, and is formed of an elastic material to transmit power to the first shaft 310 and the second shaft 320 . It absorbs the noise and vibration of the furnace.

Here, the damping member 337 includes NR (Natural Rubber), NBR (Nitrile Butadiene Rubber), CR (Chloroprene Rubber), EPDM (Ethylene Propylene Terpolymer), FPM (Fluoro Rubber), It is made of materials such as SBR (Styrene Butadine Rubber), CSM (Chlorosulphonated Polyethylene), urethane, and silicone, and acts as a damper to absorb noise and vibration.

The support members 339a and 339b provided at both ends in the axial direction of the damping member 337 are made of a plastic resin or metal material having a greater strength than the damping member 337, and the first shaft 310 and the second shaft 320 are formed. ) when the power is transmitted, the rotational torque is transmitted.

These support members 339a and 339b are integrally formed with the damping member 337, or coupling grooves 332 are formed on both sides of the damping member 337, and are press-fitted into the coupling grooves 332 of the damping member 337. and may be bonded or vulcanized to the damping member 337 in some cases.

In addition, the support protrusions 338 protruding radially inwardly are provided on the inner peripheral surfaces of the support members 339a and 339b, and the positions of the support protrusions 338 are disposed between the circumferential directions of the insertion grooves 333 and the first When the shaft 310 rotates, it is prevented from spinning or being separated.

That is, on the outer peripheral side of the power transmission member 330, the extended end 321 of the second shaft 320 is coupled to the second coupling portion 331 recessed from the outer peripheral surface of the damping member 337, so that it rotates in vain or is not separable.

And, at the center of the power transmission member 330, the projection 311 is coupled to the insertion groove 333, and at the same time, the support projection 338 disposed between the insertion grooves 333 is coupled to the support groove 334, , it prevents the first shaft 310 from spinning or separating even with a strong rotational force transmitted from the motor 130 .

Therefore, even in the electric power-assisted steering device in which forward and reverse rotation of the motor 130 are repeated, torque is reliably transmitted and at the same time only the first shaft 310 and the second shaft 320 are damped by the damping member 337 . By maintaining contact, noise and vibration can be absorbed more efficiently.

Here, the amount of pressing of the damping member 337 is approximately formed to be a maximum of 10 to 15% when no external force is applied, and may be changed according to the magnitude of the transmitted driving force.

In addition, when assembling, the damping member 337 is compressed and coupled while elastically deformed by the protrusion 311 and the extended end 321 .

However, in the description of the present embodiments, it has been described that the first shaft 310 is coupled to the center of the power transmission member 330 and the second shaft 320 is coupled to the outer circumferential side, but this is for explanation only as an example. , is not necessarily limited thereto, and an extended end 321 is provided on the outer peripheral side of the power transmission member 330 so that the first shaft 310 is coupled, and the protrusion 311 is coupled to the outer peripheral surface of the second shaft 320 . Note that they may be combined.

According to the present embodiments having such a structure and shape, there is an effect that the volume is greatly reduced, the number of parts is reduced and the manufacturing process is reduced compared to the conventional structure in which the inner rotor and the outer rotor are press-fitted and coupled.

In addition, according to the present embodiments, compared to the conventional power transmission member, it is possible to eliminate noise due to the clearance between the shaft and the power transmission member, and noise caused by vibration and noise when power is transmitted at the portion where the two shafts are coupled. has the effect of being able to prevent

In the above, even though it has been described that all components constituting the present embodiments are combined or operated as one, the present embodiments are not necessarily limited to these embodiments. That is, within the scope of the present embodiments, all of the components may operate by selectively combining one or more.

In addition, terms such as "comprises", "comprises" or "have" described above mean that the corresponding component may be embedded, unless otherwise stated, excluding other components. Rather, it should be construed as being able to include other components further. All terms, including technical or scientific terms, have the same meaning as commonly understood by those of ordinary skill in the art to which these embodiments belong, unless otherwise defined. Terms that are generally used, such as those defined in the dictionary, should be interpreted as being consistent with the meaning of the context of the related art, and are not interpreted in an ideal or excessively formal meaning unless explicitly defined in the present embodiments.

The above description is merely illustrative of the technical idea of the present embodiments, and various modifications and variations are possible without departing from the essential characteristics of the embodiments by those of ordinary skill in the art to which the present embodiments belong. will be. Accordingly, the embodiments disclosed in the present embodiments are for explanation rather than limiting the technical spirit of the present embodiments, and the scope of the technical spirit of the present embodiments is not limited by these embodiments. The protection scope of the present embodiments should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present embodiments.

130: motor 310: first shaft
311: protrusion 320: second shaft
321: extended end 330: power transmission member
331: second coupling portion 333: insertion groove
337: damping member 339a, 339b: support member

Claims (8)

a first shaft having at least one protrusion on its outer circumferential surface;
a second shaft having at least one extended end portion extending in the axial direction at the end portion;
An insertion groove into which the protrusion is inserted is provided in the center, a first coupling part through which the first shaft is coupled is provided, and a second coupling part on which the extended end is seated is formed on the outer periphery to transmit power to which the second shaft is coupled absence;
includes,
The power transmission member,
a damping member provided with the first coupling part and the second coupling part on the central part and the outer circumferential surface, respectively, and formed of an elastic material;
a support member provided at both ends of the damping member in the axial direction and formed of a material greater than the strength of the damping member;
including,
The support member is integrally formed with the damping member, or coupling grooves are formed on both sides of the damping member to be press-fitted into the coupling grooves. The method of claim 1,
When two or more of the protrusions are provided, the protrusion and the insertion groove are spaced apart from each other in the circumferential direction of the first shaft. 3. The method of claim 2,
When two or more extended ends are provided, the reducer of the electric power-assisted steering device, characterized in that the extended ends are disposed between the protrusions in the circumferential direction. 4. The method according to claim 2 or 3,
The protrusion and the insertion groove are arranged at equal intervals in the circumferential direction of the first shaft, and the extended ends are arranged at the same intervals as the protrusions on both sides of the circumferential direction. delete delete The method of claim 1,
The support member is provided with a support protrusion protruding radially inward from an inner circumferential surface. 8. The method of claim 7,
The support protrusion is disposed between the circumferential direction of the insertion groove.

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