JP2003118597A - Vehicular steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow one steering motor, when it is made impossible to output for any reason with its output shaft being difficult to be operated, to be covered by the other steering motor for driving a steering shaft of a steering mechanism. SOLUTION: This vehicular steering device comprises two steering motors 31, 32 adapted for driving the steering shaft (a relay rod 14) of the steering mechanism 10 to right and left sides, the steering motors 31, 32 having driving force enough to steer the steering wheel 40, both steering motors 31, 32 having the output shafts 31a, 32a connected to the steering shaft 14 via a differential mechanism 20. The differential mechanism 20 has two input elements 21, 22 connected to the two output shafts of the steering motor and an output element 23 connected to the steering shaft of the steering mechanism. It also has two- system power transmission passages, and either of the two having trouble in power transmission can be covered by the other for serving power transmission.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system for steering steered wheels in a vehicle.

[0002]

2. Description of the Related Art As one of vehicle steering systems, there is a vehicle steering system in which a steering shaft of a steering mechanism can be driven by two steering motors, which is disclosed in, for example, JP-A-2001-80530. There is. In the vehicle steering system disclosed in the publication, the rotors of the steering motors are arranged on a common drive shaft (rotation output shaft), and the drive shaft is a component of a ball screw steering mechanism. Is integrally rotatably connected to the ball nut, and by rotating the ball nut with the output torque of both steering motors, the screw shaft that is the steering shaft of the steering mechanism is driven in the axial direction. It is possible to steer the steered wheels.

[0003]

In the above-described conventional vehicle steering system, the common drive shaft is directly rotated by the rotors of the two steering motors. When one of the steering motors cannot output and the rotor rotation resistance increases, it becomes difficult for the remaining steering motors to rotate the common drive shaft, and the steering shaft of the steering mechanism is rotated. Is difficult to drive, that is, it is difficult to steer the steered wheels.

[0004]

In order to solve the above-mentioned problems, the present invention provides a vehicle steering system in which two steering motors can drive a steering shaft of a steering mechanism. It is characterized in that the output shaft of the rudder motor is connected to the steered shaft through a differential mechanism (the invention according to claim 1). In this case, it is also possible to provide a prohibition means for prohibiting the movement of the output shaft of the steering motor when one of the steering motors becomes incapable of outputting (the invention according to claim 2). is there.

The above-mentioned differential mechanism has two input elements connected to the output shafts of two steering motors and one output element connected to the steering shafts of the steering mechanism, and has two systems. The power transmission path is provided, and even when one of the power transmission paths cannot transmit the power, the remaining power transmission paths can transmit the power. The above-mentioned prohibiting means prohibits the rotation of the output shaft when the output shaft of the steering motor is rotationally driven, and the output shaft when the output shaft of the steering motor is axially driven. Axial movement is prohibited.

[0006]

In the vehicle steering system according to the present invention (the invention according to claim 1), the differential mechanism is interposed between the output shafts of the two steering motors and the steering shafts. When one of the power transmission paths in the dynamic mechanism cannot transmit power, the remaining power transmission paths can transmit power,
If for some reason one of the steering motors fails to output and its output shaft becomes inoperable, the remaining steering motors can drive the steering shaft of the steering mechanism. It is possible to steer the steered wheels.

Further, in the vehicle steering system according to the present invention (the invention according to claim 2), the differential mechanism is interposed between the output shafts of the two steering motors and the steering shaft. When one of the two power transmission paths is unable to transmit power, the remaining power transmission path is capable of transmitting power, and when either one of the two steering motors cannot output, the same steering motor Since a prohibition unit that prohibits the movement of the output shaft of the above is provided, if one of the steering motors cannot be output for some reason, the output shaft of the steering motor remains in the state of being prohibited. It is possible to drive the steered shaft of the steered mechanism by means of the steered motor, and thereby the steered wheels can be steered.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 schematically show a vehicle steering system according to the present invention. In this vehicle steering system, a steering mechanism 10 that is not mechanically connected to an operating means such as a steering wheel (not shown). A ball screw type steering mechanism is adopted as the steering mechanism 10, and the steering mechanism 10 includes two steering motors 3 via a planetary gear type differential mechanism 20.
1, 32 (motors assembled to the vehicle body by a motor housing).

The steering mechanism 10 includes a screw shaft 11 mounted on a part of the vehicle body via a bracket 19 so as to be rotatable but axially immovable, and a ball nut 1 mounted on the screw shaft 11.
2, a support arm 13 that non-rotatably supports the ball nut 12, and a steering shaft that integrally supports the support arm 13 and is attached to a part of the vehicle body via a bracket 19 so as to be movable left and right. Relay rod 14 and tie rods 1 connected to the left and right ends of the relay rod 14, respectively.
5 and the knuckle arm 16 and the like. In the steered mechanism 10, the steered wheels 40 are steered via the tie rods 15 and the knuckle arms 16 by moving the relay rod 14 left and right.

As shown in FIG. 2, the differential mechanism 20 has a sun gear 21 and a ring gear 22 as input elements and a carrier 23 as an output element, and has a power transmission path from the sun gear 21 to the carrier 23. There is a power transmission path from the ring gear 22 to the carrier 23, and when one of the power transmission paths cannot transmit power (that is, when the sun gear 21 or the ring gear 22 cannot rotate), the remaining power transmission path has Power can be transmitted. The sun gear 21 is integrally rotatably connected to the output shaft 31 a of the steering motor 31. The ring gear 22 is the steering motor 3
It meshes with a pinion 33 that is integrally rotatably mounted on the second output shaft 32a. The carrier 23 is integrally rotatably connected to the screw shaft 11 of the steering mechanism 10.

Each of the steering motors 31 and 32 is a rotary drive motor (for example, a motor with a reducer or an ultrasonic motor) that makes it difficult for the output shafts 31a and 32a to rotate when de-energized, and a steering wheel (not shown). The operation is controlled by a control device (not shown) according to the amount of steering to other operating means.Each output torque is a value required for steering when the vehicle is stopped (it is possible to perform stationary steering). Value). Further, although the steering motors 31 and 32 cannot independently obtain the necessary steering speed at the normal time, the output speeds are set so that the steering motors 31 and 32 can be operated at the same time to obtain the necessary steering speed at the normal time. ing.

Further, in this embodiment, the steering motors 31 and 32 are provided with sensors S1 and S2 capable of detecting the amount of rotation of the output shafts 31a and 32a (which can also be performed at the rotational speed), and the sensor S1. , S2, the rotation amount of the carrier 23 calculated from the detected values, and the screw shaft 11 of the steering mechanism 10.
Of the steering motors 31, 32, the sensors S1, S2, etc. by comparing the rotation amount of each of the sensors (the rotation amount calculated from the detection value of the sensor S3 provided corresponding to the screw shaft 11). When the abnormality is detected, the turning motor on the side where the abnormality is detected is prohibited from rotating, and the abnormality notifying means (lamp, buzzer, etc., not shown) is activated.

In this embodiment constructed as described above, when an operating means such as a steering wheel (not shown) is operated, the control device is operated in response to a steering input to the operating means.
(Not shown) controls the operation of the steering motors 31, 32.
Therefore, when the steering device is normal, the screw shaft 11 of the steering mechanism 10 is rotationally driven by the driving force of the both steering motors 31 and 32 via the differential mechanism 20, and the screw shaft 11 is rotated according to the steering input. The relay rod 14 of the rudder mechanism 10 is moved left and right, and the left and right steered wheels 40 are steered at a desired steer speed according to the steering input.

In this embodiment, the differential mechanism 20 is interposed between the output shafts 31a and 32a of the two steering motors 31 and 32 and the screw shaft 11 of the steering mechanism 10, and the differential mechanism 20 is provided. Even when one of the power transmission paths in 20 cannot transmit power, the remaining power transmission paths can transmit power. For this reason, when one of the steering motors 31 or 32 cannot be output for some reason and the output shaft 31a or 32a cannot be rotationally operated (at the time of abnormality), the remaining steering motors 32 or 32 are The screw shaft 11 of the steering mechanism 10 can be rotationally driven by 31 and the left and right steered wheels 40 can be steered.

In the above embodiment, the steering motor 3
A rotary drive motor (for example, a motor with a speed reducer or an ultrasonic motor) in which the output shafts 31a and 32a cannot rotate when de-energized is used as the motors 1 and 32, but as shown schematically in FIG. In addition, as the steering motors 31 and 32, after adopting a rotary drive motor (for example, a brushless motor) that allows the output shafts 31a and 32a to rotate when not energized,
It is also possible to implement by providing the electromagnetic brakes 51 and 52 which can fix each output shaft 31a and 32a non-rotatably.
Each of the electromagnetic brakes 51 and 52 corresponds to the corresponding steering motor 3
1 and 32 are prohibition means for prohibiting rotation of the output shafts 31a and 32a of the steered motors 31 and 32 when the output of the steering motors 31 and 32 is disabled due to an abnormality in power supply, and the operation is controlled by a control device (not shown). It is supposed to be done.

In the embodiment shown in FIG. 3, when one of the two steered motors 31 and 32 is in the output disabled state,
The electromagnetic brake 51 or 52 prohibits rotation of the output shaft 31a or 32a of the corresponding steering motor 31 or 32. Therefore, if the output of one of the steering motors 31 or 32 is disabled for some reason, the electromagnetic brake 51 or 52 prohibits the rotation of the output shaft 31a or 32a of the steering motor 31 or 32. In this state, the remaining steering motor 32 or 31 can drive the screw shaft 11 of the steering mechanism 10 to rotate, whereby the left and right steered wheels 40 can be steered.

In each of the above embodiments, two input elements connected to the output shafts (31a, 32a) of the two steering motors and the steering shaft of the steering mechanism (relay rod 1
In addition to having one output element connected to 4), it has two power transmission paths, and when one of the power transmission paths cannot transmit power, the remaining power transmission path can transmit power. Differential mechanism, planetary gear type differential mechanism 2
0 was adopted, but the same differential mechanism was used in FIGS.
Alternatively, each differential mechanism 120, 22 schematically shown in FIG.
It is also possible to implement it by adopting 0,320. Each differential mechanism 120 shown in FIG. 4, FIG. 5 or FIG.
Even in the embodiment in which 220 and 320 are adopted, it is possible to obtain the same effects as those in the above embodiment.

The differential mechanism 120 shown in FIG. 4 is a harmonic drive type differential mechanism, in which a wave generator 121 and a worm gear 122 are used as input elements, a flexspline 123 is used as an output element, and the worm gear 12 is used.
A worm wheel 124 having a circular spline is interposed between the No. 2 and the flexspline 123, and has a power transmission path from the wave generator 121 to the flexspline 123 and a power transmission path from the worm gear 122 to the flexspline 123. However, even when one of the power transmission paths cannot transmit power (that is, when the wave generator 121 and the worm gear 122 cannot rotate), the remaining power transmission paths can transmit power.

The wave generator 121 is integrally rotatably connected to the output shaft 31a of the steering motor 31. The worm gear 122 is used for the output shaft 3 of the steering motor 32.
It is connected to 2a so as to be integrally rotatable. The flexspline 123 is a screw shaft of the steering mechanism (screw shaft 11 in FIG. 1).
It is connected to the so that it can rotate. Worm wheel 1
24 is supported so as to be rotatable with respect to the vehicle body and immovable in the axial direction.

The differential mechanism 220 shown in FIG. 5 is a differential mechanism combining a screw feed mechanism and a slide mechanism,
Each of the worm gears 221 and 222 has an input element, and the screw spline shaft 223 has an output element.
Worm wheels 224 and 225 are respectively interposed between the Nos. 1 and 222 and the screw spline shaft 223,
When there is a power transmission path from the worm gear 221 to the screw spline shaft 223 and a power transmission path from the worm gear 222 to the screw spline shaft 223, and one of the power transmission paths cannot transmit power (that is, the worm gear 221 or The remaining power transmission path can transmit power even when 222 cannot rotate.

The worm gear 221 is integrally rotatably connected to the output shaft 31a of the steered motor 31. The worm gear 222 is connected to the output shaft 32a of the steering motor 32 so as to be integrally rotatable. Screw spline shaft 22
3 is rotatably and immovably supported by a support arm 13 of the steering mechanism 10 via a support 18, and is connected to a relay rod 14 via the support arm 13 of the steering mechanism 10. It is possible to move left and right integrally with the relay rod 14 of the steering mechanism 10.

The worm wheel 224 is rotatably supported on the vehicle body and is immovable in the axial direction. The worm wheel 224 meshes with the worm gear 221 on the outer periphery and is screwed on the screw portion 223a of the screw spline shaft 223 on the inner periphery. is doing. The worm wheel 225 is supported so as to be rotatable with respect to the vehicle body and immovable in the axial direction, and has a worm gear 2 on its outer periphery.
22 and is spline-fitted to the spline portion 223b of the screw spline shaft 223 at the inner circumference.

The differential mechanism 320 shown in FIG. 6 is a differential mechanism having two screw feeding mechanisms, and the worm gear 3
21 and 322 are input elements, the holder 323 is an output element, the worm wheel 324 and the screw shaft 325 are interposed between the worm gear 321 and the holder 323, and the worm wheel 326 is interposed between the worm gear 322 and the holder 323. , Which has a power transmission path from the worm gear 321 to the holder 323 and a power transmission path from the worm gear 322 to the holder 323, and one of the power transmission paths cannot transmit power (that is, the worm gear 321 or 322 rotates). When it is not possible), the remaining power transmission path can transmit power.

The worm gear 321 is integrally rotatably connected to the output shaft 31a of the steering motor 31. The worm gear 322 is integrally rotatably connected to the output shaft 32 a of the steering motor 32. The holder 323 is integrally supported by the support arm 13 of the steering mechanism 10.
In addition, in this embodiment, the steering motor 32 is installed in the holder 32.
It is attached to a movable support 327 that moves integrally with the unit 3, and can be moved left and right.

The worm wheel 324 is supported so as to be rotatable with respect to the vehicle body and immovable in the axial direction, meshes with the worm gear 321 on the outer circumference, and has the screw shaft 32 on the inner circumference.
It is screwed to 5. The screw shaft 325 is screwed into the inner circumferences (center portions) of the worm wheels 324 and 326, and is supported so as to be movable in the axial direction by the rotation of the worm wheels 324 and 326. The worm wheel 326 is supported so as to be rotatable with respect to the holder 323 and immovable in the axial direction, and has an outer periphery that supports the worm gear 32.
2 and is screwed to the screw shaft 325 at the inner circumference.

In the differential mechanism 320 shown in FIG. 6, the screw shaft for moving the movable support 327 by rotationally driving the output shaft 31a of the steering motor 31 and the output shaft 32a of the steering motor 32 are provided. Although the screw shaft 325 also serves as the screw shaft for moving the holder 323 by rotationally driving, it is also possible to separately configure each screw shaft for implementation.

Further, in each of the above-described embodiments, the embodiments in which the output shafts of both the turning motors are rotationally driven have been described. However, the output shafts of at least one turning motor are driven in the axial direction. The present invention can also be implemented in an embodiment having a configuration, and in this case, it is necessary to employ a differential mechanism adapted to the movement of the output shaft of each steering motor. Further, each of the steering motors described above is not limited to an electric motor, and various other drive motors (for example, a hydraulic motor, a pneumatic motor, etc.) can be adopted.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an embodiment of a vehicle steering system according to the present invention.

FIG. 2 is a diagram schematically showing a configuration of the differential mechanism shown in FIG.

3 is a view partially corresponding to FIG. 2 showing another embodiment of the vehicle steering system according to the present invention.

FIG. 4 is a diagram schematically showing a first modified embodiment of a differential mechanism that can be adopted in implementing the present invention.

FIG. 5 is a diagram schematically showing a second modified embodiment of the differential mechanism that can be adopted in implementing the present invention.

FIG. 6 is a diagram schematically showing a third modified embodiment of a differential mechanism that can be adopted in implementing the present invention.

[Explanation of symbols]

10 ... Steering mechanism, 11 ... Screw shaft, 12 ... Ball nut,
13 ... Support arm, 14 ... Relay rod, 15 ... Tie rod, 16 ... Knuckle arm, 20 ... Differential mechanism, 21 ...
Sun gear, 22 ... Ring gear, 23 ... Carrier, 31,
32 ... Steering motors, 31a, 32a ... Output shaft, 40 ... Steering wheels.

Claims (2)

[Claims] 1. A vehicle steering system in which a steering shaft of a steering mechanism can be driven by two steering motors, wherein output shafts of both steering motors are connected to the steering shafts via a differential mechanism. A steering device for a vehicle, which is characterized by being connected. 2. The vehicle steering system according to claim 1, further comprising a prohibiting means for prohibiting a movement of an output shaft of the steering motor when one of the steering motors is in an output disabled state. A vehicle steering device characterized by being provided.