KR102161283B1 - Structure of worm gear for electric power steering system - Google Patents

Abstract

The present invention relates to a worm wheel structure of an electric power steering apparatus having an improved structure to provide a simple structure of a rattle buffer structure to a worm wheel, as well as to provide a buffering force for a load transmitted from a steering shaft and a worm shaft, as well as easy assembly. will be.
The worm wheel structure of the electric power steering apparatus according to the present invention includes a worm wheel body having a through hole formed in the center and a plurality of coupling holes formed at an outer edge of the through hole spaced apart from each other, and the worm wheel body is combined to be in surface contact with the left side of the worm wheel body, and at the center. A combination of a worm wheel hub formed with a fitting hole for the steering shaft to be axially coupled, a hub cover coupled to the right side of the worm wheel body to make surface contact, and the worm wheel hub and the hub cover to be in close contact with both left and right sides of the worm wheel body Means, first and second protrusions formed to protrude from surfaces facing each other of the worm wheel hub and the hub cover to be fitted into the coupling holes of the worm wheel body, and the first and second protrusions fitted into the coupling holes It consists of a damper that is coupled to each surround the outer periphery and is elastically deformed by an external load.

Description

Structure of worm gear for electric power steering system

The present invention relates to a worm wheel structure of an electric power steering device, and in particular, a simple structure of a rattle buffer structure is provided to the worm wheel, and the structure is easy to assemble and to impart a buffer force to the load transmitted from the steering shaft and the worm shaft. Relates to a worm wheel structure of an improved electric power steering device.

In general, the steering system of a vehicle is a device that allows the driving direction of the vehicle to be changed at the will of the driver, and is a device that assists the driver to advance the vehicle in the desired direction by arbitrarily changing the rotation center of the vehicle's front wheel. .

In such a steering device of a vehicle, there is an electric power steering device (MDPS: motor-driven power steering) in which the steering force is controlled by a motor, which is based on the driving conditions of the vehicle detected by various sensors such as a vehicle speed sensor and a steering torque sensor. The electronic control device precisely drives the motor, and the torque generated from the motor is transmitted to the steering column or pinion through the reducer, thereby helping the driver's steering force to operate the steering column and the steering wheel connected to the pinion.

Accordingly, the electric power steering system provides a light and comfortable steering state when driving at low speeds, provides a heavy and stable steering state when driving at high speeds, and provides rapid steering operation in response to sudden emergency situations. It provides steering performance to maintain steering conditions.

These electric power steering steering devices can be divided into various types depending on the location where they are installed, mainly in conjunction with a steering column or rack bar to fix the steering shaft connecting the steering wheel of the driver's seat and the gearbox under the vehicle to the vehicle body. It is a device that installs a reducer equipped with a motor in a gearbox with a built-in pinion, and allows the rotational force of the steering wheel operated by the driver to be transmitted to the rack bar by the motor and the reducer.

When the vehicle to which the column-type electric steering device is applied is operated, a reverse input load is applied due to factors such as impact transmitted from the road surface, or gears are engaged with each other to transmit rotational force. As wear occurs gradually, in particular, as the axial play of the worm shaft increases, rattle noise is inevitably generated in the part where the worm shaft and the worm wheel engage and rotate.

In order to prevent such a phenomenon, a play preventing means is used which pressurizes the worm shaft side to eliminate a gap between the worm shaft and the worm wheel by using a rattle spring.

Therefore, a conventional column-type electric steering device generally includes a means for preventing the rattle phenomenon as described above, and this means is achieved by compensating the clearance between the worm shaft and the worm wheel gear, for example, the worm wheel A structure in which rubber structures are put at both ends or the worm wheel is tilted is applied.

As a conventional prior art for preventing rattle noise, as disclosed in Korean Patent Publication No. 10-0645766 "Rattle Noise Prevention Type Electric Steering Device for Vehicle" (Registration Date: 2006.11.06), the driver's steering force is converted into rotational force. A gap preventing means that blocks the occurrence of gap between the worm shaft rotated by the motor and the worm wheel that transmits steering power that operates the gearbox connected to the steering shaft is the end shaft portion of the worm shaft rotated by the motor assisting the steering power. A taper that applies continuous pressing force to the worm shaft by being inserted into the space between the support bearing and the inner surface of the housing containing the worm wheel that is rotated by meshing with the worm shaft to transmit rotational force to the steering shaft connected to the gearbox. It consists of a slider.

The prior art described above is applied to the worm shaft, and on the contrary, as disclosed in Korean Patent Laid-Open Publication No. 10-2012-0137027, "Electric Steering Device" (published date: 2012.12.20). , A worm shaft part equipped with a worm gear, a worm wheel part that rotates by engaging the outer circumferential surface of the worm gear, a hub part that rotates by meshing with the inner circumferential surface of the worm wheel part, and a motor part and hub part that rotates the worm shaft part to suppress noise. It includes wealth.

However, the conventional rattle prevention structure related to the worm shaft has a gap preventing means, but since it is a method of providing a continuous pressing force to the worm shaft, external shocks are directly transmitted to the worm shaft, and there is a concern that the parts may be easily damaged by repeated impacts.

In addition, the rattle prevention structure provided in the existing worm wheel is a structure that suppresses noise by having a vibration isolator having a viscous fluid and a cover plate. There is a risk of loss and there is a hassle to inject viscous fluid from time to time.

Korean Patent Publication No. 10-0645766 "Rattle noise prevention type electric steering system for vehicles" (Registration date: 2006.11.06) Korean Patent Laid-Open Publication No. 10-2012-0137027 "Electric steering system" (published date: 2012.12.20)

The present invention was created to solve the above problems in consideration of the above problems, and its purpose is to provide a simple structure of a rattle buffer structure to a worm wheel rather than a worm shaft, while simplifying assembly and providing a buffering force against the load transmitted from the steering shaft and the worm shaft. It is to provide a worm wheel structure of an electric power steering device whose structure is improved so that it can be applied.

The present invention for achieving the above object is a worm wheel body provided with a gear unit that is engaged with a worm shaft on an outer circumferential surface, a through hole is formed in the center, and a plurality of coupling holes are formed on the outside of the through hole, and face contact with one side of the worm wheel body. The worm wheel hub is combined so that the steering shaft is fitted in the center and the fitting hole is formed, the hub cover is coupled to the other side of the worm wheel body so as to be in surface contact, and the worm wheel hub and the hub cover are coupled to both left and right sides of the worm wheel body. A coupling means, first and second protrusions formed to protrude from surfaces facing each other of the worm wheel hub and the hub cover, and fitted into the coupling holes of the worm wheel body, and the first and second protrusions fitted into the coupling holes It is characterized in that it comprises a damper that is coupled to surround the outer circumference of each of the outer circumferences and elastically deformed by an external load.

The worm wheel hub is provided with a fitting portion protruding toward the worm wheel main body at an edge of the fitting hole to be fitted into the through hole.

It is preferable that the damper adopts a material that is elastically deformed as an external load is transmitted and can be restored by its own elastic force.

The coupling means includes an assembly hole formed to coincide with each other in the first and second protrusions, an assembly bolt coupled to pass through the assembly hole, and an end portion of the assembly bolt to connect the worm wheel hub and the hub cover to the worm wheel body. It is equipped with a fastening nut for restraining it.

In addition, the coupling means further includes an assembly groove and an assembly protrusion formed in an uneven shape on surfaces of the first and second protrusions facing each other.

The coupling hole is formed to protrude inside and further includes a seating portion for supporting the damper coupled to the first and second projections.

In the present invention, the worm wheel hub and the first and second protrusions protruding from the hub cover are coupled so as to be accommodated in a plurality of coupling holes formed in the worm wheel body, and then an elastically deformable damper is interposed between the first and second protrusions and the coupling hole. , Compared to the complicated rattle prevention structure provided at both ends of the existing worm shaft, it can be applied to the worm wheel structure with a simple configuration, thereby having a useful effect of reducing manufacturing cost.

In addition, the present invention has a useful effect of improving productivity by easily assembling the worm wheel structure, and performing a shock absorbing function for the load transmitted from the steering shaft as well as the load transmitted from the worm shaft.

1 is a perspective view showing an electric power steering apparatus to which the present invention worm wheel structure is applied.
Figure 2 is an exploded perspective view showing the configuration of the worm wheel structure of the electric power steering apparatus according to the present invention.
Figure 3 is an exploded perspective view showing Figure 2 from a different angle.
Figure 4 is a combined state diagram of Figure 2.
5 is a front view of a worm wheel structure of the electric power steering apparatus according to the present invention and a cross-sectional view taken along line AA.
Figure 6 is a cut-away perspective view of Figure 4;
Figure 7 is a state of use of the present invention.

The worm wheel structure of the electric power steering apparatus according to the present invention will be described with reference to FIGS. 1 to 6, wherein a through hole 110 is formed in the center and a plurality of coupling holes are spaced apart from each other at the outer edge of the through hole 110 ( A worm wheel hub 200 having a worm wheel body 100 in which 120) is formed, and a fitting hole 210 that is coupled to the left side of the worm wheel body 100 so as to be in contact with the left side of the worm wheel body 100 and is fitted in the center so that the steering shaft 30 is axially coupled. Wow, the hub cover 300 coupled to the right side of the worm wheel body 100 so as to be in surface contact, and the worm wheel hub 200 and the hub cover 300 are coupled to be in close contact with both left and right sides of the worm wheel body 100 And the first and second protrusions formed to protrude on the surfaces facing each other of the worm wheel hub 200 and the hub cover 300 to be fitted into the coupling hole 120 of the worm wheel body 100 ( 220 and 320, and rectangular closed dampers 400A and 400B that are coupled to independently surround the outer circumferences of the first and second protrusions 220 and 320 fitted into the coupling hole 120 and elastically deformed by an external load. Is composed. The plurality of coupling holes 120 are formed to be spaced apart from each other in the circumferential direction of the worm wheel body 100.

In more detail, the worm wheel body 100 is configured in a ring shape, manufactured by injection molding, and has a structure in which a plurality of coupling holes 120 are perforated so that left and right sides communicate.

In the coupling hole 120, the left and right dampers 400A and 400B are in contact with each of the left and right sides in the middle of the inner surface, so that a belt-shaped seating portion 121 for holding the position of the dampers 400A and 400B is provided. It protrudes. The dampers 400A disposed on one side of the seating portion 121 are separated from each other and are provided with a plurality of dampers 400A respectively inserted into the plurality of coupling holes 120. Likewise, the dampers 400B disposed on the other side of the seating portion 121 are provided with a plurality of dampers 400B separated from each other and inserted into the plurality of coupling holes 120, respectively.

The worm wheel main body 100 is provided with a gear unit 102 that is engaged with the worm shaft 20 in gear mesh around the outer circumferential surface.

In addition, the worm wheel body 100 has a structure in which the central portion has a stepped concave to both sides so that the worm wheel hub 200 and the hub cover 300 are accommodated on both left and right sides, and are coupled to be bound through a coupling means. .

The hub cover 300 has a structure in which a connection hole 310 is perforated so that the steering shaft 30 is press-fitted in the center.

In the worm wheel hub 200, the edge portion of the fitting hole 210 located at the center protrudes toward the worm wheel body 100, and the through hole 110 of the worm wheel body 100 and the connection hole 310 of the hub cover 300 The fitting portion 215 to be fitted is extended.

The worm wheel hub 200 has a plurality of first protrusions 220 protruding toward the hub cover 300 on one side, and the hub cover 300 has a plurality of second protrusions 220 corresponding to the first protrusions 220 on the other side. The protrusion 320 is formed to protrude toward the worm wheel hub 200.

In addition, the first and second protrusions 220 and 320 are assembled so that their ends face each other, and each assembly hole 225 and 325 is formed in the center.

An assembly bolt 510 is passed through the assembly holes 225 and 325 of each of the first and second protrusions 220 and 320, and a fastening nut 520 is fastened to the end of the assembly bolt 510, so that the hub cover 300 and the worm wheel hub 200 ) Is bound to the left and right sides of the worm wheel body 100.

In addition, each of the first and second protrusions 220 and 320 has an assembly groove 222 and an assembly protrusion 322 in an uneven shape in the middle of the faces facing each other, and the assembly groove 222 and the assembly protrusion 322 Is coupled with each other to guide the assembly of the first and second protrusions (220,320) and the assembly of the worm wheel hub 200 and the hub cover 300, as well as positioning the assembly holes (225,325) on the same line to assemble bolt 510 It performs the function of guiding the assembly of the department.

More preferably, the assembly groove 222 is formed to be inclined so that the width becomes narrower toward the inside, and the assembly protrusion 322 is also formed in a shape corresponding to the inner surface of the assembly groove 222, so that the assembly properties can be improved. do.

That is, in the coupling means of the present invention, assembly holes 225 and 325 positioned on the same straight line are formed in each of the first and second protrusions 220 and 320 facing each other, and each assembly bolt 510 in each assembly hole 225 and 325 It has a coupling structure that is fastened with a fastening nut 520 after passing through.

In addition, the coupling means of the present invention may employ a rivet (not shown) instead of the assembly bolt 510 in the assembly holes 225 and 325 of the first and second protrusions 220 and 320.

The dampers 400A and 400B are configured in an "O" ring shape and are coupled to surround the outer circumferential surfaces of the first and second protrusions 220 and 320.

In addition, the dampers (400A, 400B) are elastically deformable by the load transmitted from the worm shaft (20) or the steering shaft (30) and can be restored by their own elastic force.For example, a material such as rubber, urethane, and silicone may be used. I can.

The unexplained reference numeral "50" denotes a case of a worm reducer.

The worm wheel structure 10 of the present invention having such a structure, first briefly describing the assembly process, is assembled so that the worm wheel hub 200 is accommodated in a concave portion in the middle of one side of the worm wheel body 100, and the worm wheel body 100 After allowing the hub cover 300 to be accommodated in a concave portion in the middle of the other side, the assembly bolt 510 and the fastening nut 520 are used to integrally bind.

At this time, in the worm wheel hub 200, the fitting portion 215 passes through the through hole 110 of the worm wheel body 100 and enters into the connection hole 310 of the hub cover 300 and is fitted.

In addition, the first protrusion 220 of the worm wheel hub 200 is supported by being in contact with the left side of the coupling hole 120 of the worm wheel body 100, and the second protrusion 320 of the hub cover 300 is the worm wheel body ( It is located on the right side of the coupling hole 120 of 100) so that the ends of the first and second protrusions 220 and 320 are arranged in a direction facing each other, and are fitted into the coupling hole 120.

At this time, the dampers 400A and 400B are coupled to surround the outer circumferential surfaces of the first and second protrusions 220 and 320, so that the first and second protrusions 220 and 320 are inserted into the coupling hole 120, so that the seating portion 121 ) Is interposed between the outer circumferential surfaces of the first and second protrusions 220 and 320 and the inner circumferential surface of the coupling hole 120 as the dampers 400A and 400B are in contact with both left and right sides of the ).

For this reason, the dampers 400A and 400B are, as shown in FIG. 7, when the upper, lower or lateral load transmitted from the worm shaft 20 or the steering shaft 30 is transmitted, the dampers 400A and 400B are ,It has a role of mitigating the rattle phenomenon by performing a shock absorbing function while being deformed by the load transmitted in the downward and lateral directions to generate a clearance (G).

Subsequently, when the first and second protrusions 220 and 320 are inserted into the coupling hole 120, the assembly holes 225 and 325 are arranged on the same line, and the assembly bolt 510 is passed through the assembly holes 225 and 325, and then assembled. By fastening the fastening nut 520 to the end of the bolt 510, the assembly by the assembly bolt 510 is made easy, and the worm wheel hub 200 and the worm wheel hub 200 by the tightening force of the assembly bolt 510 and the fastening nut 520 It is possible to integrally bind the hub curve to both left and right sides of the worm wheel body 100.

Accordingly, in the present invention, the worm wheel hub 200 and the first and second protrusions 220 and 320 protruding from the hub cover 300 are coupled to be accommodated in the coupling hole 120 formed in a plurality of the worm wheel body 100. The dampers 400A and 400B that can be elastically deformed are interposed between the 1,2 protrusions 220 and 320 and the coupling hole 120, so that the worm wheel structure has a simple configuration compared to the complex rattle prevention structure provided at both ends of the existing worm shaft 20. As it can be applied, manufacturing cost can be reduced, and assembly is easy to improve productivity, and a shock absorbing function can be performed not only for the load transmitted from the worm shaft 20 but also the load transmitted from the steering shaft 30. Has a useful effect.

On the other hand, as described above, when the assembly holes 225 and 325 of the first and second protrusions 220 and 320 are riveted by using a rivet rather than the assembly bolt 510, there is an advantage of preventing the nut loosening phenomenon of the bolt.

The present invention described above has a technical idea that can alleviate the rattle phenomenon caused by an external force transmitted from the worm shaft 20 or the steering shaft 30 to the worm wheel structure, and within the scope not departing from the concept and scope of the present invention. Any number of variations can be implemented in.

10: worm wheel structure 20: worm shaft
30: steering shaft 50: case
100: worm wheel body 102: gear unit
110: through hole 120: coupling hole
121: seat 200: worm wheel hub
210: fitting hole 215: fitting portion
220: first protrusion 222: assembly groove
225,325: assembly work 300: hub cover
310: connection hole 320: second protrusion
322: assembly protrusion 400A,400B: damper
510: assembly bolt 520: fastening nut
G: Gap

Claims (6)

The worm wheel body 100 is provided on the outer circumferential surface of the worm shaft 20 and a gear unit that is engaged in gear engagement with the worm shaft 20, a through hole 110 is formed in the center, and a plurality of coupling holes 120 are formed outside the through hole 110,
A worm wheel hub 200 coupled to one side of the worm wheel body 100 to make surface contact and having a fitting hole 210 formed therein so that the steering shaft 30 is fitted in the center thereof,
A hub cover 300 coupled to the other side of the worm wheel body 100 so as to be in surface contact,
A coupling means for coupling the worm wheel hub 200 and the hub cover 300 to both left and right sides of the worm wheel body 100,
First and second protrusions 220 and 320 formed to protrude on the surfaces facing each other of the worm wheel hub 200 and the hub cover 300 to be fitted into the coupling hole 120 of the worm wheel body 100,
It includes a rectangular closed damper (400A, 400B) coupled to independently surround the outer peripheries of the first and second protrusions 220 and 320 fitted into the coupling hole 120 and elastically deformed by an external load,
The coupling means,
Assembly holes 225 and 325 formed to coincide with each other on the first and second protrusions 220 and 320, respectively,
Including an assembly groove 222 and an assembly protrusion 322 formed in an uneven shape on surfaces facing each other of the first and second protrusions 220 and 320,
The assembly groove 222 and the assembly protrusion 322 are concave-convexly coupled to each other to guide the assembly of the first and second protrusions 220 and 320 and the assembly of the worm wheel hub 200 and the hub cover 300 , And the assembly holes (225,325) are located on the same line,
The coupling hole 120 is formed to protrude from the inside and includes a seating portion 121 for supporting the dampers 400A and 400B coupled to the first and second protrusions 220 and 320,
The dampers 400A and 400B are respectively disposed on both sides of the seating portion 121,
The plurality of coupling holes 120 are formed to be spaced apart from each other in the circumferential direction of the worm wheel body 100,
The damper 400A disposed on one side of the seating portion 121 is provided with a plurality of dampers 400A separated from each other and inserted into the plurality of coupling holes 120, respectively,
The worm wheel structure of an electric power steering apparatus, wherein the dampers 400B disposed on the other side of the seating portion 121 are separated from each other and provided with a plurality of dampers 400B respectively inserted into the plurality of coupling holes 120. The method according to claim 1,
The worm wheel hub 200 includes a fitting portion 215 protruding toward the worm wheel body 100 at the edge of the fitting hole 210 and fitted into the through hole 110. Worm wheel structure. The method according to claim 1,
The damper (400A, 400B) is a worm wheel structure of an electric power steering apparatus, characterized in that the material is elastically deformed as an external load is transmitted and can be restored by its own elastic force. The method according to claim 1,
The coupling means,
An assembly bolt 510 coupled to pass through the assembly holes 225 and 325, and
The worm wheel structure of an electric power steering apparatus further comprising a fastening nut 520 fastened to the end of the assembly bolt 510 to constrain the worm wheel hub 200 and the hub cover 300 to the worm wheel body 100. delete delete

Images