KR100726588B1 - The removal structure assembly clearance of rack assist typed motor driven power steering apparatus - Google Patents

Abstract

An assembling clearance removing structure of a rack assist type electric power steering device is provided to reduce noise and vibration caused by clearance formed in a long-time use and prevent steering feeling delay by strongly pushing a clearance standard point with a separate lock nut and removing the assembling clearance between components and to improve convenience in maintaining tolerance about a contact between combined components. An assembling clearance removing structure of a rack assist type electric power steering device comprises first and second rack housings(11,13) of a rack assembly(R) and first and second bearings(19,18). The first and second bearings are installed at two lateral sides to actively rotate a ball nut(16) press-fitted into a driving pulley(15). The first bearing is disposed in a motor support combining step(12) of the first rack housing to form a clearance standard point(A). The second bearing is disposed in an extension combining step(5a) of a belt housing(5) to be supported by a supporting bush(17) press-fitted into the ball nut at the opposite side of the first bearing, and tightly contacted on the inner surface of the motor supporting combining step by receiving the pressing force through a lock nut(20) pressing with combining torque. The lock nut inserts and constrains an insertion fixing step projected from a belt housing combining step(14) of the second rack housing combined at the lateral side of the extension combining step of the belt housing.

Description

The clearance structure assembly clearance of rack assist typed motor driven power steering apparatus

1 is a block diagram of the assembly clearance clearance removal structure of the rack assist type electric power steering apparatus according to the present invention

Figure 2 (a), (b) is a block diagram of the lock nut for clearance clearance assembly assembly according to the present invention

3 is a cross-sectional view having an assembly tolerance clearance removing structure according to the present invention.

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

1: driving means 2: motor

3: motor pulley 4: belt

5: belt housing 5a: extension coupling end

10: driven means 11: first rack housing

12: motor support coupling stage 13: the second rack housing

14: belt housing coupling end 14a: insertion fixing end

15: driving pulley 16: ball nut

17: support bush 18, 19: first and second bearing

20: lock nut 21: tightening boss

22: pressure flange 23: fixing protrusion

a, b, c: 1st, 2nd, 3rd settling diameter A: clearance reference point

C: Steering column R: Rack bar

R: Rack Assembly S: Steering Wheel

T: tie rod

The present invention relates to a rack assist type electric power steering apparatus, and more particularly, to a rack assist type electric power steering apparatus which eliminates assembly tolerance play.

In general, a power steering device that generates steering force of a vehicle is designed and operated to use hydraulic pressure in order to enable quick steering while lightly and smoothly operating a steering force.

Such a power steering device can be steered with a small force, can be selected regardless of the steering force of the steering gear ratio, and can be prevented from being transmitted to the handle by absorbing the impact from the unevenness of the road surface. have.

In addition, in recent years, the electronic control unit (ECU) drives the motor according to the vehicle's driving conditions detected by the vehicle speed sensor and the steering torque sensor to provide a light and comfortable steering feeling at low speeds, and a heavy steering feeling at high speeds. Directional stability is provided, and in an emergency situation, a trend is to use an electric steering device that provides an optimum steering condition to the driver by enabling rapid steering.

Such electric steering system is usually EHPS (Electro-hydraulic Power Steering) or Motor Driven Power Steering (MDPS), the dual MDPS system, unlike the hydraulic system that forms the hydraulic pressure in the pump to assist the power (rotational power of the motor) It is a structure that assists steering power by using a motor that generates power and a worm shaft, which is a gear reducer connected to it, rotates a worm wheel connected to a steering shaft. Will assist you.

In addition, among the MDPS (Motor Driven Power Steering), R-MDPS (Rack Assist Type Electric Power Steering Device) is a type that implements shaft movement of a rack bar by receiving a driving torque from a motor. In general, the driving torque of the motor is transmitted by using a belt and a pulley to move the rack bar.

At this time, in order to axially move the rack bar by receiving the driving torque of the motor, a ball nut rotating together with the pulley is used to convert the rotational force into the axial movement force, and the ball nuts and the pulleys have both angular contact ( Angular Contact) or Spindle type bearings are selected to facilitate rotation.

In addition, the bearing supporting the pulley and the ball nut rotated through the motor driving torque to move the rack bar in the axial direction in order to remove the clearance, the clearance between shafts according to the assembly tolerances, It is assembled in a fit-to-fit manner, which pushes firmly against each of the sequentially positioned components.

However, the fitting method for removing clearance between the shafts according to the assembly tolerances is to assemble the housing forming the rack assembly while surrounding the rack bar, the pulley, the ball nut and the bearing, and at the same time, the housing portion of the bearing It is difficult to eliminate clearance between shafts by pushing the outer ring side, i.e. the cumulative assembly tolerance of each component, which makes it difficult to completely eliminate the clearance between shafts. do.

For example, if the housing tolerance is based on the assembly tolerance of the housing to which the housing is fastened, it is easy to assemble the housing but cannot be pushed hard to eliminate the assembly accumulation tolerance between the components assembled into the housing. There is a possibility that there is a possibility of noise and vibration during operation due to the clearance, and if the housing pushes the outer ring side of the bearing strongly, the assembly between the two housings which are fastened to each other often occurs. do.

Accordingly, the present invention has been made in view of the above, and in the rack assist type electric power steering apparatus of R-MDPS, a bearing portion for supporting a rotating part for axially moving the rack bar by receiving drive torque is axially oriented. The purpose of the assembly tolerance management through the housing that is assembled and fastened while strongly pushing the whole, to facilitate the tolerance management for the cumulative assembly tolerance of each component, while also providing the ease of processing.

The present invention for achieving the above object, is controlled by the ECU to determine the steering degree of the steering wheel through the sensor receives power through the belt wound on the motor pulley from the motor of the drive means for generating power, The driven means receiving the power of the drive means moves the rack bar to which the tie rods are connected by a ball nut pressed into the drive pulley on which the belt is wound, and drives the driven means to both sides of the extension coupling end of the belt housing surrounding the drive means. In the rack assist type electric power steering apparatus to which the 1st and 2nd rack housings of the rack assembly to wrap are connected,

A first and second bearings provided at both sides of the first and second bearings to smoothly rotate the ball nut pressed into the driving pulley constituting the driven means. The bearing is supported by a lock nut which presses the second bearing located in the extension engagement end of the belt housing with the tightening torque so that the bearing is supported by the support bush press-fitted to the ball nut at the opposite side of the first bearing. The lock nut is in close contact with the inner surface, and the lock nut is restrained while the insertion fixing end protruding from the belt housing coupling end of the second rack housing coupled to the extension coupling end side of the belt housing is inserted.

In addition, in the present invention, the second bearing supported by the support bush in the belt housing has its outer circumferential surface fixed to a third seating diameter formed on the inner surface of the extended engagement end, and the support bush is pushed strongly toward the first bearing to clear the clearance. The lock nut for removing the clearance with respect to the reference point, the pressure flange of the lock nut is fastened to the second seating diameter formed stepped to form a diameter larger than the third seating diameter, and formed stepped to form a diameter larger than the second seating diameter The insertion fixing end projecting from the belt housing coupling end of the second rack housing is inserted into the seating diameter to restrain the lock nut.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows a block diagram of the assembly clearance clearance removal structure of the rack assist type electric power steering apparatus according to the present invention, the present invention is a rack assist type electric power steering apparatus of R-MDPS of the steering column (C) According to the steering means 1 and the steering wheel S, which are controlled by an ECU (Engine Control Unit) which determines the steering degree of the steering wheel S mounted at the top through a sensor and generates power, The rack assembly (R) for moving the tie rod (T) connected to the wheel and the driven means 10 for linearly moving the rack assembly (R) by receiving the power of the drive means (1).

Here, the drive means 1 is a motor (2) controlled by the ECU, the motor pulley (3) fixed to the shaft of the motor (2) and the belt 4 wound around the motor pulley (3) It is composed of a belt housing 5 surrounding a portion of the rack assembly (R) while wrapping.

In addition, the driven means 10 is coupled to both side portions of the extension coupling end (5a) extending from the belt housing (5) of the drive means 1 to surround the rack bar (r) forming a rack assembly (R) The first and second rack housings 11 and 13 and the tie rod T while being pushed into the drive pulley 15 rotated through the belt 4 wound around the motor pulley 3 of the drive means 1. Ball nut (16) formed on the inner surface of the rack bar (r) connected to the linear movement, and supported by the ball nut (16) inside the motor support coupling end (12) of the first rack housing (11) Supported by the support bush 17 press-fitted into the ball nut 16 inside the extended engagement end 5a of the belt housing 5 to which the first bearing 19 and the second rack housing 13 are connected. Clear the side surface of the first bearing 19 in close contact with the first rack housing 11 by pressing the side portion of the second bearing 18 in the second bearing 18 and the extension coupling end 5a. To the lance control point (A) It consists of a lock nut 20 for removing the play.

In addition, the lock nut 20 has a relatively large diameter as compared to the fastening boss 21 having a hole formed in the center, as shown in Figure 2, a plurality of fixing projections 23 on the rim surface at equal intervals It is made of a pressing flange 22 formed, the fixing projection 23 is usually formed by a screw.

At this time, the clearance removal structure formed in the driven means 10 is, as shown in Figure 3, the first, second, third seating diameter formed with a step in the inner surface of the extension coupling end (5a) of the belt housing ( The second bearing 18 supported by the support bushing 17 is formed through a, b, c, i.e., a third seating diameter c having a diameter at which the second bearing 18 to be inserted is fixed. The pressing bush 22 of the lock nut 20 is fastened to the second seating diameter b, which is fixed and has a relatively large diameter so as to have a step in the third seating diameter c, thereby supporting the support bushing 17 with the first. The second rack housing is pushed toward the bearing 19 to remove the clearance to the clearance reference point A, and the first seating diameter a makes a relatively large diameter so as to step on the second seating diameter b. An insertion fixing end 14a protruding from the belt housing coupling end 14 of 13 is inserted to push the lock nut 20.

At this time, the belt housing coupling end 14 of the second rack housing 13 is in close contact with the side of the extension coupling end 5a of the belt housing 5, of course.

In addition, the fixing protrusions 23 formed on the pressure flange 22 of the lock nut 20 are fastened by digging into the second seating diameter b of the extension coupling end 5a, or the second seating diameter b. Formation of fixing projection grooves having the same shape in the form of a screw.

Hereinafter, the operation of the present invention will be described in detail with reference to the accompanying drawings.

Rack assist type electric power steering device of the present invention R-MDPS is controlled by an ECU (Engine Control Unit) to determine the steering degree of the steering wheel (S) mounted on the top of the steering column (C) through a sensor When driven means 10 for linearly moving the rack assembly R by receiving the power of the driving means 1 for generating the assembly, the clearance due to the assembly tolerances, etc. of the components constituting the driven means 10 The assembly is made with the) removed, thereby significantly reducing the generation of noise during operation of the drive means 1 and the driven means 10.

That is, the rack bar (1) is extended to one side of the extension coupling end 5a of the belt housing 5 surrounding the motor 2, the motor pulley 3 and the belt 4 of the driving means 1 driven by the control of the ECU. r) is coupled to the motor support coupling end 12 of the first rack housing (11, 13) surrounding, the inner surface of the motor support coupling end 12, as shown in Figure 3 the clearance reference point (A) The first bearing 19 is kept in close contact with the side.

Subsequently, the support bush 17 is press-fitted into the side surface of the ball nut 16 press-fitted to the drive pulley 15 to which the belt 4 is connected at the motor support coupling end 12 of the first rack housings 11 and 13. In this case, the second bearing 18 fixed to the support bush 17 is also inserted into the third seating diameter c formed on the inner surface of the extension coupling end 5a of the belt housing 5.

As such, the second bearing 18 is formed on the inner surface of the extension coupling end 5a in a state where the second bearing 18 is positioned at the third seating diameter c formed on the inner surface of the extension coupling end 5a of the belt housing 5. 2, the lock nut 20 is fastened to the seating diameter b. At this time, as the pressure flange 22 of the lock nut 20 is fastened to the second seating diameter b, an assembly torque of about 20 to 25 N is achieved. The second side of the bearing 18 is strongly pressed, which pushes the support bushing 17, the ball nut 16, and the driving pulley 15 toward the first bearing 19, thereby providing the first rack housing 11. The clearance to the clearance reference point (A) based on the side of the first bearing (19) in close contact with the motor support coupling end 12 of the to eliminate the accumulated tolerance of the tolerances of each component.

At this time, when the lock nut 20 is fastened using the fastening boss 21 of the lock nut 20, the fixing protrusion 23 formed on the edge surface of the pressure flange 22 is extended to the belt housing 5. The second mounting diameter b, which is an inner surface of the end 5a, is excavated or moved while pressing the side surface of the second bearing 18 by screwing.

Subsequently, the lock nut 20 is released for smooth operation of the first and second bearings 19 and 18 (that is, the state of low preload), and then the lock nut 20 is returned to the assembly torque of about 5N. After tightening, tighten or coke the lactite to prevent loosening.

As such, after the lock nut 20 is fastened, the belt housing coupling end 14 of the second rack housing 13 is coupled to complete the assembly, that is, the protruding insertion fixing end of the belt housing coupling end 14. When the 14a is inserted into the first seating diameter a formed in the extension coupling end 5a of the belt housing 5, the insertion fixing end 14a opens the side surface of the pressure flange 22 of the lock nut 20. While pushing, the side of the belt housing coupling end 14 is in close contact with the side of the extension coupling end 5a, and the assembly is completed.

On the other hand, since the operation of the rack assist electric power steering apparatus which is R-MDPS which concerns on this invention is the same as that of being used, detailed description is abbreviate | omitted.

As described above, according to the present invention, when assembling each component constituting the driven means for manipulating the rack bar for moving the tie rod, the assembly tolerance formed by each component while strongly pushing to the clearance reference point using a separate lock nut Since the clearances are eliminated, the noise and vibration caused by the formation of the clearances during long-term operation and the steering feeling delay effect can be prevented.

In addition, since the present invention removes the play while pushing strongly using a separate lock nut, there is an effect that it is not necessary to precisely maintain the tolerance management for the contact between the parts to be coupled to each other.

Claims (3)

Power is controlled by the belt 4 wound on the motor pulley 3 from the motor 2 of the drive means 1 which is controlled by an ECU that determines the steering degree of the steering wheel S through a sensor to generate power. Received, the rack bar is connected to the tie rod (T) by the ball nut (16) pressed into the drive pulley (15), the driven means (10) receiving the power of the drive means (1) wound belt 4 (1) the second and second rack housings of the rack assembly (R) which move the (r) and surround the driven means (10) on both sides of the extension coupling end (5a) of the belt housing (5) surrounding the drive means (1). In the rack assist type electric power steering apparatus which 11,13) is connected to, The first rack housing (11) of the first and second bearings (19, 18) provided at both sides to smoothly rotate the ball nut (16) pressed into the drive pulley (15) forming the driven means (10). The first bearing 19, which is located inside the motor support coupling end 12 of the C1) and constitutes the clearance reference point A, is supported by the support bush in which the ball nut 16 is press-fitted from the opposite side of the first bearing 19. The motor support coupling end receives the pressing force by the lock nut 20 which presses the second bearing 18 located in the extension coupling end 5a of the belt housing 5 with the tightening torque so as to be supported by the 17. 12) the fixed fixing end protruding from the belt housing coupling end 14 of the second rack housing 13 is in close contact with the inner surface, the lock nut 20 is coupled to the side of the extension coupling end (5a) of the belt housing (5). Assembly tolerance clearance removal structure of the rack assist type electric power steering apparatus, characterized in that the restraint (14a) is inserted. 2. The second bearing 18 supported by the support bushing 17 in the belt housing 5 has an outer circumferential surface thereof in a third seating diameter c formed in the inner surface of the extension coupling end 5a. Is fixed, The lock nut 20 which strongly pushes the support bush 17 toward the first bearing 19 to remove the clearance to the clearance reference point A has a diameter larger than the third seating diameter c, and is formed stepwise. The pressing flange 22 of the lock nut 20 is fastened to the second seating diameter b, An insertion fixing end 14a protruding from the belt housing coupling end 14 of the second rack housing 13 is inserted into the first seating diameter a formed with a diameter larger than the second seating diameter b. Assembly clearance gap clearance structure of the rack assist type electric power steering apparatus, characterized in that the lock nut 20 is restrained. According to claim 1, The lock nut 20 has a relatively larger diameter than the fastening boss 21 having a hole formed in the center, the second seating diameter (b) of the extension coupling end (5a) to the rim surface Assembly gap clearance removal structure of the rack assist type electric power steering device, characterized in that consisting of a pressing flange 22 formed with a plurality of fixing projections 23 fastened at equal intervals.

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