JPH11182643A - Roller transmitting device, and motor driven power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suitably maintain preload state between a driving side roller and a driven side roller, and an intermediate roller for a long time without requiring troublesome adjusting operation. SOLUTION: An outer peripheral surface of a driving side roller 1 interlockingly rotating following a driving shaft 10 is provided with taper parts 11, 12 whose diameters expand taper-shapedly from its center to both ends. An annular intermediate roller 3 equipped with a pair of annular rollers 30, 31 which are equipped with wedge surfaces 32, 33 having a gradient substantially equal to these, respectively, in its inner periphery, and a pressing spring 34 for energizing these in the mutually separating direction is used. This intermediate roller is loosely fitted on the outer side of the driving side roller 1, the wedge surfaces 32, 33 on the inner periphery is rotation-touched to the taper parts 11, 12, and the outer peripheral surface to the outer peripheral surface of a driven side roller 2, and inside and outside of the intermediate roller 3 are nipped and floatably supported between the both rollers 1, 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller transmission for transmitting torque from a driving side to a driven side via rollers that rotate by rotating each other.

[0002]

2. Description of the Related Art As one type of a transmission device for transmitting torque between a drive shaft and a driven shaft, a drive roller that rotates in conjunction with the drive shaft and a driven roller that rotates in conjunction with the driven shaft are known. Roller transmissions are used which make rolling contact on their respective outer peripheral surfaces and transmit torque using friction at the rolling contact portions.

[0003] This roller transmission has the advantage that quiet operation is possible as compared with widely used gear transmissions. However, in order to stably perform reliable torque transmission, the roller transmission is required. There is a problem that means for applying a sufficient preload to the rolling contact portion between the side roller and the driven roller to prevent the occurrence of slip at the rolling contact portion is indispensable.

[0004] The application of the preload is performed by directly adjusting the position of one or both of the drive shaft and the driven shaft with respect to the other, and adjusting the center distance between the drive roller and the driven roller. Although it can be performed, it is difficult to configure the drive shaft and the driven shaft so that their positions can be adjusted. So conventionally,
Between the driving roller and the driven roller, an intermediate roller for adjusting the preload that comes into contact with each other is arranged, and the position of the intermediate roller can be adjusted with respect to the driving roller and the driven roller.
A configuration for providing a desired preload is widely used.

FIG. 8 is a front view of a conventional roller transmission having an intermediate roller for adjusting a preload. As shown in the drawing, a drive roller 10 and a driven roller 2 are supported by a drive shaft 10 and a driven shaft 20 arranged in parallel with each other so as to be integrally rotatable. The outer peripheral surfaces 2 are opposed to each other with an appropriate interval. An intermediate shaft 40 is disposed between the drive shaft 10 and the driven shaft 20 at a position shifted a suitable length to one side from a straight line connecting the axes of the two shafts, in parallel with these. An intermediate roller 4 is rotatably supported on the outer peripheral surfaces of the driving roller 1 and the driven roller 2.

[0006] The intermediate shaft 40 is provided so as to be movable toward the axis of the drive shaft 10 and the driven shaft 20, and the preload is applied to the intermediate shaft 40 as shown by a white arrow in the figure. The intermediate roller 4 is moved and pressed against the driving roller 1 and the driven roller 2 supported on the driving shaft 10 and the driven shaft 20, respectively, and the position of the intermediate shaft 40 is adjusted in a state where the intermediate roller 4 is appropriately pressed. It is performed by the procedure of fixing.

[0007]

However, in the preloading procedure performed as described above, when the intermediate shaft 40 supporting the intermediate roller 4 is fixed, the intermediate roller 4 is attached to the driving roller 1 and the driven roller 2. It is difficult to maintain a proper pressing state of the intermediate shaft 40, and there is a problem that the preload is likely to be excessive or insufficient after the fixing, and the transmission efficiency is reduced. However, there is a problem that a complicated operation such as using a jig for maintaining the pressing state is required.

Further, even when the preload is properly adjusted, it is inevitable that the preload is reduced due to wear of the rolling contact portion, and it is difficult to maintain a desired transmission efficiency for a long period of time. was there.

For example, in an electric power steering apparatus configured to assist the steering of an automobile with an electric motor, a transmission system for directly or indirectly transmitting the rotation of the electric motor to a steering shaft for steering is provided. As described above, it is desired to use a roller transmission having a quiet operation sound. However, there is a problem that the steering assist force applied to the steering shaft gradually decreases due to the above-described problem of deterioration of the transmission efficiency, which causes deterioration of the steering feeling.

The present invention has been made in view of the above circumstances, and it has been possible to satisfactorily adjust the preload state of the driving roller, the driven roller and the intermediate roller for a long period of time without the need for complicated adjustment work. An object of the present invention is to provide a roller transmission that can be maintained, and to provide an electric power steering device that can be operated quietly using the roller transmission.

[0011]

According to the present invention, there is provided a roller transmission having a structure in which torque is transmitted between a driving roller and a driven roller via intermediate rollers which are respectively in contact with the driving roller and the driven roller. In the transmission device, a taper portion is provided on one or both outer peripheral surfaces of the drive-side roller and the driven-side roller, the diameter of which increases in a tapered shape from a central portion in the axial direction toward both sides. It is interposed between a pair of annular rollers having a wedge-shaped cross section which radially widens from one side to the other side at an inclination substantially equal to that of the tapered portion, and both opposed annular rollers, and separates them. Biasing means for biasing in the direction, the inner peripheral surface is rolled on one of the drive roller and the driven roller, and the outer peripheral surface is rolled on the other, so that the roller is floatingly supported between the two rollers. Features.

In the present invention, an annular intermediate roller is loosely fitted to one of the drive-side roller and the driven-side roller, and the inner peripheral surface of the intermediate roller is brought into rolling contact with the one of the rollers. The outer peripheral surface of the intermediate roller is brought into rolling contact with the other roller, and the intermediate roller is held in a floating state by being sandwiched between the two rollers. The outer peripheral surface of one or both of the driving side roller and the driven side roller is provided with a tapered portion that expands in diameter from the center in the axial direction toward both sides, and the intermediate roller having an annular shape has a slope substantially equal to the tapered portion. And a pair of annular rollers having a wedge-shaped cross-section that radially widens and biasing means for biasing the opposed annular rollers in a direction away from each other. When the roller is supported between the roller and the driven roller as described above, the pair of annular rollers are separated from each other by the urging of the urging means. Alternatively, the roller is pressed against the tapered portion of the driven roller, and a sufficient preload is generated therebetween. Further, when wear occurs on the rolling contact surfaces of the two, the annular roller is further separated by the urging force of the urging means, the pressure contact state is secured, the shortage of the preload is automatically adjusted, and the appropriate pressure is maintained for a long time. The preload state is maintained.

Further, the electric power steering apparatus according to the present invention is an electric power steering apparatus configured to transmit a rotational torque of a motor driven in accordance with a steering operation to a steering shaft and to assist steering performed in accordance with the operation of the steering shaft. In the power steering apparatus, the above-described roller transmission device is configured by a driving-side roller driven by the motor, a driven-side roller that rotates in conjunction with the steering shaft or a transmission shaft to the steering shaft, and an intermediate roller that rolls and contacts with each of these. It is characterized by having been done.

In the present invention, it is not necessary to adjust the preload as described above, and a roller transmission device that automatically adjusts the deficiency of the preload with time is provided by a transmission system from an electric motor for steering assistance to a steering shaft. To realize torque transmission which is excellent in quietness and does not cause a reduction in transmission efficiency over a long period of time.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a front view showing a configuration of a roller transmission according to the present invention, and FIG. 2 is a side view of the same.

The illustrated roller transmission is similar to the conventional roller transmission shown in FIG. 8 in that a driven roller 1 supported on a drive shaft 10 and a driven roller 2 supported on a driven shaft 20 are provided. Thus, the torque transmission is performed. The drive shaft 10 and the driven shaft 20 are supported in parallel with each other so as to be rotatable around their respective axes. The drive roller 1 and the driven roller 2 are connected to each other by the drive shaft 10 and the driven shaft 20. At positions corresponding to the axial direction, they are respectively mounted so as to be integrally rotatable.

On the outside of the driving roller 1, as shown in FIG.
An annular intermediate roller 3 is loosely fitted. The intermediate roller 3 has its inner peripheral surface rolled on the outer peripheral surface of the driving roller 1 and its outer peripheral surface rolled on the outer peripheral surface of the driven roller 2. , Which are floatingly supported between the rollers 1 and 2 so as to be clamped from inside and outside.

FIG. 3 is a sectional view of the driving roller 1 and the intermediate roller 3 loosely fitted to the driving roller 1. As shown in the drawing, the intermediate roller 3 is a pair of annular rollers disposed to face each other in the axial direction.
30 and 31 are provided. These annular rollers 30 and 31 have a wedge-shaped cross section having wedge surfaces 32 and 33 whose inner peripheral surfaces are tapered from one side in the axial direction to the other side. Are positioned coaxially with their small diameter sides facing each other, and are urged in a direction away from each other by a plurality of pressing springs (urging means) 34, 34. It is configured by being connected. Press spring 3
The interposition positions of 4, 34... Are indicated by broken lines in FIG.
It is set so as to be substantially equally distributed in the circumferential direction.

As shown in the figure, the outer peripheral surface of the driving roller 1 on which the intermediate roller 3 is loosely fitted has tapered portions 11 and 12, which are tapered from the center in the width direction to both sides.
The inclination of wedge surfaces 32, 33 on the inner periphery of the annular rollers 30, 31 is substantially equal to the inclination of the tapered portions 11, 12. The intermediate roller 3 is a driving roller 1
Than the maximum outer diameter D ₁ of the Yes and sized to have a sufficiently large minimum inner diameter D _2, loosely intermediate roller 3 to the outside of the driving roller 1, so as to be performed with a sufficient margin is there.

FIG. 4 is an enlarged sectional view of a rolling contact portion between the intermediate roller 3 and the driving roller 1 and the driven roller 2. The intermediate roller 3 loosely fitted to the outside of the driving roller 1 is sandwiched between the driven roller 2 and the driving roller 1 at a portion facing the driven roller 2 as shown in FIG. As shown, it is supported in a floating state between both rollers 1 and 2,
At this time, a pair of annular rollers 3 constituting the intermediate roller 3
The inner wedge surfaces 32 and 33 of 0 and 31 are in rolling contact with the tapered portions 11 and 12 provided on the outer peripheral surface of the drive-side roller 1 respectively. It comes into rolling contact with the outer peripheral surface of the driven roller 2 configured as a cylindrical surface.

In such a rolling contact state, the pair of annular rollers 30 and 31 constituting the intermediate roller 3 are caused by the spring force F of the pressing springs 34, 34. As shown by, they are urged to move away from each other,
It is about to be pushed into a wedge-shaped gap formed between the tapered portions 11 and 12 provided on the outer peripheral surface of the driving roller 1 and the outer peripheral surface of the driven roller 2.

As a result, the wedge surfaces 32 and 33 on the inner circumference of the annular rollers 30 and 31 are opposed to the tapered portions 11 and 12 of the drive-side roller 1 which are in rolling contact with each other, and the outer circumferential surfaces of the annular rollers 30 and 31 are The driven roller 1 and the driven roller 2 are held between the driven roller 1 and the driven roller 2 by being pressed against the outer peripheral surface of the driven roller 2 by a component force of the spring force F in a direction orthogonal to the respective contact surfaces. Rolling contact is performed under sufficient preload via the intermediate roller 3, and stable torque transmission from the driving roller 1 to the driven roller 2 can be performed stably.

As described above, such preloading is performed by positioning the driving roller 1 in which the intermediate roller 3 is loosely fitted to the outside at a regular position facing the driven roller 2 and causing the outer peripheral surface of the intermediate roller 3 to move. It can be easily obtained by performing an assembling procedure of rolling and contacting the outer peripheral surface of the driven-side roller 2, and the preload adjustment work conventionally required is completely unnecessary.

A driving shaft 10 for supporting the driving roller 1
When there is a dimensional error in the distance between the shaft and the driven shaft 20 supporting the driven-side roller 2, which causes a shape error in the wedge-shaped gap formed between the rollers 1 and 2. Also, the annular roller 30, which constitutes the intermediate roller 3,
31 follows and increases or decreases the mutual separation distance by the action of the spring force F of the pressing springs 34, 34..., And keeps the pressing state against the driving roller 1 and the driven roller 2; It is done.

In the following operation as described above, the rolling contact surface between the driving roller 1 and the driven roller 2 and the intermediate roller 3 is worn,
The same operation is performed even when a gap is generated between the rollers, whereby the preload applied at the time of assembly is maintained, the initial transmission efficiency can be maintained for a long time, and reliable torque transmission can be achieved. Can be done.

FIGS. 5 and 6 are enlarged sectional views of the vicinity of the rolling contact portion showing another embodiment of the roller transmission according to the present invention. In FIG. 5, tapered portions 21 and 22 are provided on the outer peripheral surface of the driven roller 2, and the intermediate roller 3 loosely fitted to the driving roller 1 is configured such that the outer peripheral surface that comes into rolling contact with the driven roller 2 has the tapered portion 21. A pair of annular rollers 30, 31 having wedge surfaces 32, 33 having inclinations substantially equal to those of 21, 22 and press springs 34, 34 for urging them in the separating direction are provided.

In FIG. 6, tapered portions 11, 12 and tapered portions 21, 22 are provided on the outer peripheral surfaces of the driving roller 1 and the driven roller 2, respectively. A pair of annular rollers 30, 31 having wedge surfaces 32, 33
, And press springs 34 that urge these in the separating direction.

In this embodiment as well, similarly to the embodiment shown in FIG. 4, the driving roller 1 and the driven roller 2 are brought into rolling contact with the intermediate roller 3 under a sufficient preload via the intermediate roller 3 to drive the roller. Reliable torque transmission from the side roller 1 to the driven roller 2 can be stably performed. Further, the intermediate roller 3 may be configured to be loosely fitted to the outside of the driven roller 2 and to be floatingly supported by being held between the driven roller 1 and the intermediate roller 3.

FIG. 7 is a partially cutaway front view showing an application example of the roller transmission configured as described above to an electric power steering apparatus. The rack shaft 5 as a steering axis in the figure is slidably supported in the axial direction inside the rack housing H ₁ forming the lateral direction extending in-cylinder-shaped body, not shown. Rack respective ends of the rack shaft 5 which projects on both sides of the housing H _1, are connected through respective tie rods 50, 50 to the left and right steered wheels (not shown) (only one side is shown), the rack housing H ₁ The sliding of the rack shaft 5 is transmitted to the left and right steering wheels via the tie rods 50, 50, and these are steered.

[0030] The intermediate portion of the rack housing H _1, pinion housing H ₂ is continuously provided to the embodiments is crossing this the axis. Inside the pinion housing H _2, the pinion shaft 6 rotatably at about its axis are supported. The pinion shaft 6 in FIG. 1, only the protruding end of the upper part of the pinion housing H ₂ is is shown, connected to a steering wheel (not shown) via a protruding Extension end, according to the operation of the steering wheel for steering the shaft It is designed to rotate around.

[0031] The lower part of the pinion housing H pinion shaft 6 which extends into the interior of _2, the pinion (not shown) are formed integrally. Further, the rack shaft 5 is supported to the rack housing H _1, over a suitable length, including the intersecting position between the pinion housing H _2, is formed a rack teeth (not shown), the pinion of the lower portion of the pinion shaft 6 The rotation of the pinion shaft 6 due to the operation of the steering wheel is converted into sliding in the axial direction of the rack shaft 5 by the meshing of the pinion and the rack teeth, and is connected to both ends of the rack shaft 5. It constitutes a rack and pinion type steering mechanism in which left and right steering wheels are steered.

The motor housing is mounted on the rack housing H ₁ so as to project outward at one location in the circumferential direction at a position which is separated from the continuous portion of the pinion housing H ₂ by an appropriate length in the axial direction.
51 is protruded, a motor M for steering assist, the rack shaft 5 inside of its axial center rack housing H ₁ and which
And a flange fixed to the motor seat 51.

The internal as illustrated motor seat 51, has a hollow portion communicating with the interior of the rack housing H _1, the output shaft of the motor 5 which projects the hollow portion, driving roller 1 is fitted A ring-shaped intermediate roller 3 is loosely fitted to the outside of the driving-side roller 1.

[0034] Inside the other hand rack housing H _1, rotating cylinder 8 is housed in correspondence with the connecting portion position of the motor seat 51. The rotary cylinder 8 has a four-piece integrally formed on one side thereof.
By point contact ball bearing 80, the inside of the rack housing H _1, a cylindrical body which is supported by allowing only this and rotation coaxially to the inside of the rotating cylinder 8, the middle of the rack shaft 5 Part is inserted.

The driven roller 2 is integrally formed outside the rotating cylinder 8 supported in this manner at a position corresponding to the axially extending direction with the continuous portion of the motor seat 51. Is in rolling contact with the outer peripheral surface of the intermediate roller 3 that is loosely fitted to the outside of the driving roller 1 inside the motor seat 51.

As shown in FIG. 3, the driving roller 1 has tapered portions 11 and 12 on its outer periphery, and the intermediate roller 3 has a wedge-shaped cross section having an inner peripheral surface as a wedge surface. , And a pair of annular rollers 30 and 31 having pressing forces, and pressing springs 34, 34... For urging them in directions away from each other. Thus, the roller transmission according to the present invention is configured.

The rotation of the motor M driven in accordance with the steering is transmitted to the rotary cylinder 8 via the driving roller 1, the intermediate roller 3 and the driven roller 2, and the rotation is performed. cylinder 8 keeps the arresting position by 4-point contact ball bearing 80, the rack shaft 5 in the interior of the rack housing H ₁
It is driven and rotated on the same axis.

At this time, an appropriate preload is applied between the driving side roller 1 and the driven side roller 2 by the above-described operation of the intermediate roller 3, so that the rotating cylinder 8 as a driven shaft is used as a driving shaft. The rotation torque of the output shaft of the motor M is:
It is transmitted reliably and stably over a long period of time. This is because, by performing a simple assembling operation for fixing the motor M at a predetermined position of the motor seat 51 together with the driving roller 1 and the intermediate roller 3 loosely fitted thereto, a complicated operation for adjusting the preload is performed. This is realized without the need for a device, and the number of assembling steps can be reduced.

On the other end face of the rotating cylinder 8 rotating as described above, a plurality of feed rollers 7, 7.
Are mounted on the outer peripheral surface of the rack shaft 5 projecting to the same side. These feed rollers 7,
Are rotatably supported by separate support shafts 70 inclined at the same angle in the circumferential direction with respect to the axis of the rotary cylinder 8.

When the rotary cylinder 8 is rotated by the transmission from the motor M, the feed rollers 7, 7,...
Rolls along a spiral trajectory orthogonal to each of the other support shafts 70, 70..., And the rack shaft 5 frictionally acts on a rolling contact portion with each feed roller 7 along each rolling trajectory. The force is pushed by the axial component of the force to slide in the axial direction, and the steering performed as described above is assisted by the rotational torque of the motor M.

The mechanism for converting the rotation of the rotary cylinder 8 into the sliding of the rack shaft 5 is not limited to the above-described configuration, and another motion conversion mechanism such as a ball screw mechanism may be used. Further, it is needless to say that the roller transmission according to the present invention is not limited to a rack and pinion type steering mechanism as shown in FIG. 7, but can be similarly applied to other types of steering mechanisms.

[0042]

As described above in detail, in the roller transmission according to the present invention, an intermediate roller formed by urging a pair of annular rollers having a wedge-shaped cross section in the separating direction by urging means. The roller is loosely fitted to a driving roller or a driven roller, and is held between the inside and outside of the roller so as to be floatingly supported, and the annular roller is provided on a tapered portion provided on the outer peripheral surface of the driving roller and / or the driven roller. The inner and outer peripheral surfaces of the annular roller are pressed against the outer peripheral surfaces of the driving roller and the driven roller by the urging of the urging means, so that an appropriate preload is applied. Also, even when the rolling contact surface is worn, the pair of annular rollers constituting the intermediate roller is further separated by the urging of the urging means, and the pressure contact state is secured, and the proper pre-pressure state is maintained. To be Ri, reliable transmission of torque to the driven side roller from the drive side roller, it is possible to stably performed over a long period.

Further, in the electric power steering apparatus according to the present invention, since the above-mentioned roller transmission is used in the transmission system for transmitting the rotational torque of the steering assist motor to the steering shaft, the power transmission is excellent in quietness and for a long time. The present invention achieves excellent effects such as torque transmission that maintains high transmission efficiency without the need for complicated preload adjustment work, and achieves both reduction in assembly man-hours and improvement in reliability. To play.

[Brief description of the drawings]

FIG. 1 is a front view showing the configuration of a roller transmission according to the present invention.

FIG. 2 is a side view showing the configuration of the roller transmission according to the present invention.

FIG. 3 is a sectional view of a driving roller and an intermediate roller.

FIG. 4 is an enlarged cross-sectional view of a rolling contact portion between an intermediate roller, a driving roller, and a driven roller.

FIG. 5 is an enlarged cross-sectional view of the vicinity of a rolling contact portion showing another embodiment of the roller transmission according to the present invention.

FIG. 6 is an enlarged cross-sectional view of the vicinity of a rolling contact portion showing another embodiment of the roller transmission according to the present invention.

FIG. 7 is a partially cutaway front view showing an example in which the roller transmission according to the present invention is applied to an electric power steering device.

FIG. 8 is a front view showing a configuration of a conventional roller transmission having an intermediate roller for adjusting a preload.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 drive side roller 2 driven side roller 3 intermediate roller 5 rack shaft 7 feed roller 8 rotating cylinder 10 drive shaft 11,12 tapered portion 20 driven shaft 21,22 tapered portion 30,31 annular roller 32,33 wedge surface 34 compression spring M motor

Claims (2)

[Claims] 1. A roller transmission configured to transmit torque between a driving roller and a driven roller via an intermediate roller that is in rolling contact with each of the driving roller and the driven roller. One or both outer peripheral surfaces are provided with a tapered portion that expands in a tapered shape from the central portion in the axial direction toward both sides, and the intermediate roller is substantially the same as the tapered portion from one side in the axial direction toward the other side. A pair of annular rollers having a wedge-shaped cross section that radially widens at the same inclination,
Biasing means interposed between the opposed annular rollers and biasing them in a direction away from each other, an inner peripheral surface of one of the driving roller and the driven roller, and an outer peripheral surface of the other. A roller transmission, wherein each roller is rolled and supported between two rollers in a floating manner. 2. An electric power steering apparatus configured to transmit a rotational torque of a motor driven in accordance with a steering operation to a steering shaft and to assist steering performed in accordance with the operation of the steering shaft. The roller transmission device according to claim 1, wherein the driven roller, a driven roller that rotates in conjunction with the steering shaft or a transmission shaft to the steering shaft, and an intermediate roller that rolls on each of these rollers are configured. Electric power steering device.