WO2012017886A1

WO2012017886A1 - Reaction torque actuator of steer-by-wire steering device

Info

Publication number: WO2012017886A1
Application number: PCT/JP2011/067054
Authority: WO
Inventors: 桜井良
Original assignee: Ntn株式会社
Priority date: 2010-08-06
Filing date: 2011-07-27
Publication date: 2012-02-09
Also published as: JP2012035738A; JP5675207B2

Abstract

Provided is a reaction torque actuator of a steer-by-wire steering device, which enables size and weight reductions and achieves steering feeling without uncomfortable feeling. This reaction torque actuator generates steering reaction force at a steering wheel in a steer-by-wire steering device in which steering is performed by the steering wheel that is not mechanically coupled to a steering shaft for turning. A reaction torque actuator is provided with a motor (2) which is a source of generation of the steering reaction force, a deceleration mechanism (3) which transmits, as reaction torque, the output of the motor (2) to an operation shaft (1b) of a steering wheel (1), and a torque damper (5) which reduces fluctuations in the reaction torque transmitted to the operation shaft (1b). The motor (2), the deceleration mechanism (3), and the torque damper (5) are arranged coaxially with the operation shaft (1b) and coupled in an arrangement sequence.

Description

Reaction force torque actuator for steer-by-wire steering system

Related applications

This application claims the priority of Japanese Patent Application No. 2010-177307 filed on Aug. 6, 2010, which is incorporated herein by reference in its entirety.

The present invention relates to a reaction force torque actuator of a steer-by-wire type steering apparatus that is steered by a steering wheel that is not mechanically connected to a steering shaft for turning.

In a steer-by-wire type steering device, reaction force torque (acting in a direction opposite to the rotation direction of the steering wheel) acts on the rotation operation of the operation shaft of the steering wheel so that the operator who operates the steering wheel feels an appropriate response. A reaction force torque actuator that generates torque) is provided.

As such reaction force torque actuators, those directly connected to a motor (for example, Patent Document 1), those using a speed reduction mechanism in which gears are arranged on a plurality of axes (for example, Patent Document 2), and those using a cycloid speed reduction mechanism (For example, patent document 3) etc. are proposed.

JP 2008-126665A JP 2006-15891 A Japanese Patent Laid-Open No. 2005-199937

The direct-coupled type reaction force torque actuator disclosed in Patent Document 1 is obtained by directly connecting a motor that is a reaction force generation source to an operation shaft of a steering wheel. In order to generate the same steering reaction force, there is a problem that a large motor must be used at high cost.

Since the reaction force torque actuator does not require high rotation and high torque is sufficient, it is sufficient to operate the steering wheel from a motor that is a reaction force generation source, like the reaction force torque actuator disclosed in Patent Document 2. It is effective to use a speed reduction mechanism for transmitting torque to the shaft. However, since the reaction force torque actuator disclosed in Patent Document 2 uses a speed reduction mechanism in which gears are arranged on a plurality of axes, the size of the actuator increases, and the space occupied by the steering mechanism in the steer-by-wire steering device increases. There is a problem of doing.

On the other hand, the reaction force torque actuator disclosed in Patent Document 3 uses a cycloid reduction mechanism as a reduction mechanism, so that space can be saved. However, in this case, vibration due to gear noise or backlash of the speed reduction mechanism, and motor cogging are amplified through the speed reduction mechanism, resulting in a problem that the steering feeling is lowered. In addition, in order to reduce the deterioration of the steering feeling due to the fluctuation of the cogging torque of the motor, there are some which are provided with a torque damper like the reaction force torque actuator disclosed in Patent Document 1.

An object of the present invention is to provide a reaction force torque actuator for a steer-by-wire type steering apparatus that can be reduced in size and weight and can realize a steering feeling without a sense of incongruity.

A reaction force torque actuator in a steer-by-wire type steering device according to the present invention is a reaction force torque actuator that performs steering with a steering wheel that is not mechanically connected to a steering shaft for turning and generates a steering reaction force on the steering wheel. A motor that is a source of the steering reaction force, a speed reduction mechanism that transmits the output of the motor as a reaction torque to the operation shaft of the steering wheel, and a variation in the reaction force torque transmitted to the operation shaft. A torque damper to be reduced, and the motor, the speed reduction mechanism, and the torque damper are arranged on the same axis as the operation shaft and connected in the arrangement order.

According to the reaction force torque actuator of this configuration, the output of the motor is transmitted to the steering wheel operation shaft as a reaction force torque at a predetermined reduction ratio through the speed reduction mechanism, so that the steering reaction according to the steering angle is transmitted to the steering wheel. Generate power. Since the output of the motor is transmitted to the operation shaft of the steering wheel at the reduction ratio of the reduction mechanism, a sufficiently large steering reaction force can be generated in the steering wheel even if a small motor is used.

In particular, in this reaction force torque actuator, the motor, the speed reduction mechanism, and the torque damper are arranged and connected in the arrangement order on the same axis as the operation shaft of the steering wheel. And weight reduction is possible. In addition, a torque damper is provided to reduce fluctuations in the reaction torque transmitted to the steering wheel operating shaft. This reduces vibration due to motor cogging and gear noise in the speed reduction mechanism, and reduces steering force on the steering wheel. The ring can be prevented from lowering, and a steering feeling without discomfort can be realized.

In the present invention, the speed reduction mechanism may be any one of a planetary gear speed reducer, a wave gear speed reducer, and a planetary roller speed reducer. These planetary gear reducers, wave gear reducers, and planetary roller reducers all provide a large reduction ratio and can be further reduced in size.

In this invention, a rotation limiting mechanism for limiting the range of rotation angle of the operation shaft of the steering wheel that can rotate may be provided on the same axis as the operation shaft. The steering wheel rotation limiting mechanism can be further reduced in size by being provided on the same axis as the operation shaft.

The rotation limiting mechanism may be a planetary gear reducer, and the rotation limitation of the operation shaft may be performed at a rotating portion that is decelerated with respect to the rotation of the input shaft to which rotation is input from the operation shaft.

In this case, the rotation limiting mechanism may be configured so that the rotation decelerated with respect to the rotation of the input shaft is used only for limiting the rotation of the operation shaft, and the rotation speed of the output shaft is the same as the rotation speed of the input shaft. good. If the decelerated rotation is used only for rotation limitation and the rotation speed of the output shaft is the same as the rotation speed of the input shaft, a single shaft can be used for the output shaft and the input shaft. Thereby, it becomes easy to provide the rotation limiting mechanism on the same axis as the operation shaft.

In this invention, the torque damper may be one in which a viscous fluid is sealed in a space of a housing that is sealed with an oil seal and through which an operation shaft of the steering wheel passes. In this case, the viscous fluid may be any one of silicon grease, silicon oil, and silicon gel. The torque damper using the viscous fluid is excellent in the effect of reducing the vibration caused by the cogging of the motor and the gear noise of the speed reduction mechanism, and can more effectively prevent the steering feeling from being lowered in the steering wheel.

Further, in the structure of the torque damper, the outer diameter portion of the housing penetration portion of the operation shaft or the inner wall portion of the housing may be formed in a toothed shape. In this specification, the “tooth cutting shape” refers to a shape divided into a plurality of tooth portions on which a plurality of surfaces are arranged. In this case, the frictional resistance between the operating shaft and the viscous fluid or the frictional resistance between the viscous fluid and the inner wall of the housing increases, so that the damper effect of the torque damper can be improved accordingly.

In this invention, a steering angle sensor for detecting the rotation angle of the operation shaft of the steering wheel may be provided. In this case, two or more systems of the steering angle sensors may be provided, and the failure mode may be detected by comparing the detection values of the steering angle sensors with each other.

In this invention, the motor, the speed reduction mechanism, and the torque damper may be covered with a sealed housing.

Any combination of at least two configurations disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the present invention.

The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.
It is a longitudinal cross-sectional view which shows schematic structure of the reaction force torque actuator of the steer-by-wire type steering apparatus concerning one Embodiment of this invention. It is an external appearance perspective view of the reaction force torque actuator. (A) is a front view of a speed reducer in the reaction force torque actuator, and (B) is a longitudinal sectional view thereof. FIG. 4 is a sectional view taken along line IV-IV in FIG. 1. It is a graph which shows the fluctuation | variation of the reaction force torque at the time of abbreviate | omitting the torque damper in the reaction force torque actuator. It is a graph which shows the fluctuation | variation of the reaction force torque when not omitting the torque damper in the reaction force torque actuator.

An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic diagram of a reaction torque actuator of this embodiment, and FIG. 2 shows an external perspective view thereof. This reaction torque actuator is a steering reaction force applied to the steering wheel 1 in a steer-by-wire type steering apparatus that is steered by a steering wheel 1 that is not mechanically connected to a steering shaft (not shown) for turning. Is a device that generates The steering wheel 1 includes a handle 1a that is rotated by the driver and an operation shaft 1b that is positioned at the center of rotation and rotates integrally with the handle 1a. The operation shaft 1b is inserted into a sealed housing 9 formed by connecting four housing pieces 9a to 9d arranged in the axial direction, and is rotatably supported by the first housing piece 9a via

bearings

21 and 22. The reaction force torque actuator includes a motor 2 that is a generation source of a steering reaction force, a speed reduction mechanism 3 that transmits an output of the motor 2 to the operation shaft 1b of the steering wheel 1 as a reaction force torque, and an operation shaft of the steering wheel 1. A rotation limiting mechanism 4 that limits the rotation of 1b and a torque damper 5 that reduces fluctuations in the reaction torque transmitted to the operation shaft 1b are provided.

The motor 2, the speed reduction mechanism 3, the rotation limiting mechanism 4, and the torque damper 5 are connected in the arrangement order on the same axis as the operation shaft 1 b of the steering wheel 1 and covered with the sealed housing 9. Yes. That is, the motor 2 is disposed on the extension of the operation shaft 1b in the axial direction so that the rotation shaft 6 is aligned with the operation shaft 1b of the steering wheel 1, and is covered with the fourth housing piece 9d. The shaft 6 is supported by the fourth housing piece 9d through

bearings

7 and 8. The speed reduction mechanism 3 is covered with a cylindrical third housing piece 9c, and the rotation limiting mechanism 4 is covered with a cylindrical second housing piece 9b. The torque damper 5 is covered with a cylindrical first housing piece 9a, like the operation shaft 1b.

The speed reduction mechanism 3 is composed of a two-stage planetary gear speed reducer including two planetary

gear speed reducers

10 and 11, and this is also arranged on the output side of the motor 2 so that the center of rotation is the same axis as the operation shaft 1 b. Be placed. Each of the two-stage

planetary gear reducers

10 and 11 is configured such that the sun gear is the input stage, the internal gear is fixed, and the planet carrier is the output stage. The rotating shaft 6 of the motor 2 is connected to the axis of the sun gear which is the input stage. In this way, by configuring the speed reduction mechanism 3 with the two-stage planetary

gear speed reducers

10 and 11, the optimum speed reduction ratio can be set. If the optimum reduction ratio can be set, the number of stages of the planetary gear reducer may be one or more. The speed reduction mechanism 3 may be constituted by a wave gear speed reducer or a planetary roller speed reducer instead of the planetary

gear speed reducers

10 and 11.

The rotation limiting mechanism 4 includes a planetary gear speed reducer 12, and is adjacent to the output side of the speed reducing mechanism 3, that is, adjacent to the second stage planetary gear speed reducer 12 of the speed reducing mechanism 3, so as to have the same axis as the operation shaft 1 b. Be placed. 3A and 3B show a front view and a longitudinal sectional view of the planetary gear speed reducer 12 constituting the rotation limiting mechanism 4. The planetary gear speed reducer 12 is configured such that the sun gear 12a is an input stage, the planet carrier 12c that supports a plurality of planetary gears 12b is fixed, and the internal gear 12d is an output stage. The rotating shaft 13 of the planet carrier that is the output stage of the planetary gear reducer 11 of the eye passes through the axis of the sun gear 12a and is directly connected to the operation shaft 1b of the steering wheel 1 that is the final output end of the reaction force torque actuator. Yes.

A stopper pin 14 as an engaging portion protrudes from one side of the internal gear 12d of the planetary gear speed reducer 12 constituting the rotation limiting mechanism 4 as shown in FIG. When the stopper pin 14 comes into contact with the stopper 15 fixed to the inner wall portion of the housing 9, the rotatable angle range of the operation shaft 1 b of the steering wheel 1 is limited to a predetermined angle.

In the rotation limiting mechanism 4, it is possible to arbitrarily limit the rotation angle of the operation shaft 1b by changing the reduction ratio of the planetary gear speed reducer 12. Here, the rotation of the internal gear 12d decelerated with respect to the rotation of the rotation shaft of the sun gear 12a as the input stage (equal to the rotation shaft 13 of the output stage in the speed reduction mechanism 3) is used to limit the rotation of the operation shaft 1b. Yes.

Here, the planetary carrier 12c of the planetary gear speed reducer 12 is fixed and the output of the internal gear 12d is used for rotation limitation. However, the internal gear 12d is fixed and the output of the planetary carrier 12c is rotation limited. You may use for. In addition, in the planetary gear speed reducer constituting the rotation limiting mechanism 4, the rotation reduced with respect to the rotation of the input shaft is used only for limiting the rotation of the operation shaft 1b, and the rotation speed of the output shaft is defined as the rotation speed of the input shaft. It may be the same. In this case, the rotation of the rotary shaft 13 at the output stage of the speed reduction mechanism 3 can be transmitted as it is to the operation shaft 1b via the rotation restriction mechanism 4, and the rotation restriction mechanism 4 is interposed between the speed reduction mechanism 3 and the operation shaft 1b. However, the reaction torque that is the output of the motor 2 can be transmitted to the operation shaft 1b by the reduction ratio of the speed reduction mechanism 3. Here, the rotation limiting mechanism 4 is disposed on the output side of the speed reduction mechanism 3, but the present invention is not limited to this, and may be disposed on the input side of the speed reduction mechanism 3.

The torque damper 5 is configured by sealing a viscous fluid 17 in a space inside the housing 9 that is sealed with an oil seal 16 and through which the operation shaft 1b of the steering wheel 1 passes. For example, silicon grease is enclosed as the viscous fluid 17 in this case, but silicon oil or silicon gel may be used as the viscous fluid 17. The outer diameter portion of the housing penetration portion of the operation shaft 1b is formed in a gear-cut shape as shown in FIG. 4 as a sectional view taken along line IV-IV in FIG. By setting it as this gear cutting shape, the frictional resistance between the operating shaft 1b and the viscous fluid 17 increases, and a damper effect can be raised. The gear cutting shape may be any shape as long as it increases the frictional resistance, such as a gear shape or a spline, serration or spiral. In this embodiment, gear cutting is performed on the operation shaft 1b side, but the same effect can be obtained even if gear cutting is performed on the inner wall surface of the housing 9.

The motor 2 is provided with two systems of

steering angle sensors

18 and 19 for detecting the rotation angle of the operation shaft 1b of the steering wheel 1. These

steering angle sensors

18, 19 are configured to detect the rotation angle of the rotation shaft 6 of the motor 2, but the rotation of the rotation shaft 6 of the motor 2 is steered at a predetermined reduction ratio set by the reduction mechanism 3. Since it is transmitted to the operation shaft 1 b of the wheel 1, the steering angle can be determined from the rotation angle of the rotation shaft 6 of the motor 2 detected by the

steering angle sensors

18 and 19. The steering angle detected by the

steering angle sensors

18 and 19 is input to an ECU (electric control unit) 20 that controls the entire steer-by-wire steering device, and the ECU 20 generates a steering reaction force according to the detected steering angle. Thus, the output of the motor 2 is controlled. The ECU 20 includes a microcomputer and an electronic circuit including a control program for the microcomputer.

In this embodiment, since two

steering angle sensors

18 and 19 for detecting the rotation angle of the operation shaft 1b of the steering wheel 1 are provided, the failure mode can be detected by comparing these detected values with each other. Is possible.

According to the reaction force torque actuator having this configuration, the ECU 20 controls the output of the motor 2 in accordance with the steering angle detected by the

steering angle sensors

18 and 19. The output of the motor 2 is transmitted to the operation shaft 1b of the steering wheel 1 as a reaction torque with a predetermined reduction ratio through the speed reduction mechanism 3. As a result, a steering reaction force corresponding to the steering angle is generated in the steering wheel 1. Since the output of the motor 2 is transmitted to the operation shaft 1b of the steering wheel 1 by the reduction ratio of the speed reduction mechanism 3, even if a small motor 2 is used, a sufficiently large steering reaction force can be generated in the steering wheel.

In particular, in this reaction force torque actuator, the motor 2, the speed reduction mechanism 3, the rotation limiting mechanism 4 and the torque damper 5 are arranged on the same axis as the operation shaft 1b of the steering wheel 1 and are connected in the arrangement order. Combined with the miniaturization of the motor 2, the entire apparatus can be miniaturized and lightened. In addition, since the torque damper 5 is provided at the final output stage of the reaction force torque actuator so as to reduce the variation of the reaction force torque transmitted to the operation shaft 1 b of the steering wheel 1, the cogging of the motor 2 and the reduction mechanism 3 By reducing the vibration due to the gear noise, it is possible to prevent the steering feeling at the steering wheel 1 from being lowered and to realize a steering feeling without a sense of incongruity.

5 and 6 show the torque ripple of the reaction torque transmitted from the motor 2 to the operation shaft 1b of the steering wheel 1 in the reaction force torque actuator of this embodiment, with and without the torque damper 5 being omitted. It is the graph which compared and showed. In the graph of FIG. 6 showing the case where the torque damper 5 is not omitted, the torque ripple is reduced by about 50% compared to the graph of FIG. 5 showing the case where the torque damper 5 is omitted. That is, it can be seen that the torque damper 5 is highly effective in reducing the reaction force torque fluctuation.

As described above, the preferred embodiments have been described with reference to the drawings. However, those skilled in the art will readily assume various changes and modifications within the obvious scope by looking at the present specification. Accordingly, such changes and modifications are to be construed as within the scope of the invention as defined by the appended claims.

DESCRIPTION OF SYMBOLS 1 ... Steering wheel 1b ... Steering wheel operating shaft 2 ... Motor 3 ... Deceleration mechanism 4 ... Rotation limiting mechanism 5 ... Torque damper 9 ...

Housing

10, 11 ... Planetary gear reduction gear 12 of reduction mechanism ... Planetary gear reduction gear of rotation limitation mechanism 14 ... Stopper pin 15 ... Stopper 17 ...

Viscous fluid

18, 19 ... Steering angle sensor

Claims

A reaction force torque actuator in a steer-by-wire type steering device that performs steering with a steering wheel that is not mechanically connected to a steering shaft for turning, and generates a steering reaction force on the steering wheel,
A motor that is a source of steering reaction force,
A reduction mechanism that transmits the output of the motor as a reaction torque to the operation shaft of the steering wheel;
A torque damper that reduces fluctuations in reaction torque transmitted to the operating shaft,
A reaction force torque actuator of a steer-by-wire type steering apparatus in which the motor, a speed reduction mechanism, and a torque damper are arranged on the same axis as the operation shaft and are connected in the arrangement order.
The reaction force torque actuator of the steer-by-wire type steering apparatus according to claim 1, wherein the speed reduction mechanism is one of a planetary gear speed reducer, a wave gear speed reducer, and a planetary roller speed reducer.
The reaction force torque actuator for a steer-by-wire steering device according to claim 1, wherein a rotation limiting mechanism for limiting a rotation angle range of the operation axis of the steering wheel is provided on the same axis as the operation axis.
4. The rotation limiting mechanism according to claim 3, wherein the rotation limiting mechanism is a planetary gear reducer, and the rotation of the operation shaft is limited by a rotating portion that is decelerated relative to the rotation of the input shaft to which rotation is input from the operation shaft. Reaction force torque actuator for steer-by-wire steering system.
5. The structure according to claim 4, wherein the rotation limiting mechanism uses a rotation decelerated with respect to the rotation of the input shaft only for limiting the rotation of the operation shaft, and the rotation speed of the output shaft is the same as the rotation speed of the input shaft. A reaction force torque actuator for a steer-by-wire steering system.
The reaction force torque actuator for a steer-by-wire type steering apparatus according to claim 1, wherein the torque damper is sealed with an oil seal and a viscous fluid is sealed in a space of a housing through which an operation shaft of the steering wheel passes.
7. The reaction force torque actuator for a steer-by-wire type steering apparatus according to claim 6, wherein the viscous fluid is any one of silicon grease, silicon oil, and silicon gel.
7. The reaction force torque actuator for a steer-by-wire steering apparatus according to claim 6, wherein an outer diameter portion of the housing through portion of the operation shaft or an inner wall portion of the housing has a gear-cut shape.
The reaction force torque actuator for a steer-by-wire type steering apparatus according to claim 1, further comprising a steering angle sensor that detects a rotation angle of an operation shaft of the steering wheel.
10. The reaction force torque actuator for a steer-by-wire steering device according to claim 9, wherein two or more systems of the steering angle sensor are provided, and the failure mode can be detected by comparing the detected values of the respective steering angle sensors.
The reaction force torque actuator of the steer-by-wire type steering apparatus according to claim 1, wherein the motor, the speed reduction mechanism, and the torque damper are covered with a sealed housing.