JPH0537749Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a rear wheel steering device for a front and rear wheel steered vehicle, which is equipped with an electric steering angle ratio setting device for setting the steering angle ratio between the front wheels and the rear wheels. .

[Prior art]

One of the devices of this type is Japanese Patent Application Laid-Open No. 61-163064.
It has been proposed in the Publication No. In the rear wheel steering system proposed in this publication, a single electric motor is provided as a drive means for the electric steering angle ratio setting device, and the steering angle ratio is set by energizing the electric motor. A driving means for rotationally driving the rotating body is employed.

[Problem that the invention attempts to solve]

In the conventional drive means described above, there is only one electric motor, so if this electric motor breaks down and stops operating, it becomes impossible to optimally set the steering angle ratio.

The present invention aims to improve the reliability of the system by providing the drive means with two electric motors.

[Means for solving problems]

Further, the present invention provides a planetary gear mechanism having three elements, a sun gear, a carrier, and a ring gear, as a driving means of the electric steering angle ratio setting device, and a power source from the wheel to the worm in one element of the planetary gear mechanism. A first electric motor coupled via a first worm gear with zero transmission efficiency and a second worm gear with zero power transmission efficiency from the wheel to the worm to other elements of the planetary gear mechanism. a second electric motor connected thereto, and an output shaft connected to the remaining elements of the planetary gear mechanism, the steering angle ratio being set by the output shaft by energizing the first or second electric motor; A feature of the present invention is that it employs a drive means that rotates the rotated body.

[Effect of invention]

In the rear wheel steering device according to the present invention, when one element of the planetary gear mechanism is rotated via the first worm gear by energizing the first electric motor, the rotational force is transmitted to other elements of the planetary gear mechanism. Although an attempt is made to rotate the rotating shaft of the second electric motor, the power transmission efficiency from the wheel to the worm is zero in the second worm gear interposed between other elements of the planetary gear mechanism and the second electric motor. , each member from other elements of the planetary gear mechanism to the second electric motor is not rotated and functions as a reaction force member. Therefore, by energizing the first electric motor, the output shaft connected to the remaining elements of the planetary gear mechanism can be rotated, and the rotated body for setting the steering angle ratio can be rotationally driven by the output shaft.

On the other hand, when the second electric motor is energized to rotate other elements of the planetary gear mechanism via the second worm gear, the rotational force is also transmitted to one element of the planetary gear mechanism, causing the rotating shaft of the first electric motor to rotate. I try to rotate it, but one element of the planetary gear mechanism and the first
Since the power transmission efficiency from the wheel to the worm in the first worm gear interposed between the electric motors is zero, each member from one element of the planetary gear mechanism to the first electric motor does not rotate and functions as a reaction force member. do. Therefore, by energizing the second electric motor, the output shaft connected to the remaining elements of the planetary gear mechanism can be rotated, and the rotated body for setting the steering angle ratio can also be rotationally driven by the output shaft.

[Effect of idea]

In the present invention, under normal conditions (when the electric motor is operating normally), by energizing the first electric motor, the rotated body can be rotated and the steering angle ratio can be set to the set value. The steering angle ratio can be set to a set value by rotating the rotated body by energizing the two electric motors. Therefore, the reliability of the system can be improved.

In addition, in the present invention, a planetary gear mechanism and the first and second worm gears are adopted as a mechanism for rotating the output shaft by energizing the first or second electric motor, so that the drive means rotates the two electric motors. Even though it is equipped, it is compact and can ensure good vehicle mountability.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

Figure 3 shows a rear wheel steering device for a front and rear wheel steered vehicle that is equipped with an electric steering angle ratio setting device A that sets the steering angle ratio between the front wheels WF and the rear wheels WR. The device is exactly the same as the device proposed in Japanese Patent Application Laid-Open No. 163064/1983, except for the drive means B for rotationally driving the pinion shaft 10. Therefore, the configuration of the driving means B will be explained in detail below, and the explanation of the other configurations will be omitted.

As shown in FIGS. 1 and 2, the driving means B is a planetary gear mechanism 20 comprising three elements: a sun gear 21, a carrier 22, and a ring gear 23.
, a first electric motor 41 connected to the ring gear 23 of the planetary gear mechanism 20 via the first worm gear 30, and a sun gear 2 of the planetary gear mechanism 20.
1 through a second worm gear 50, and an output shaft 60 integrally connected to the carrier 22 of the planetary gear mechanism 20, as shown in FIG. The output shaft 60 is connected to the pinion shaft 10 via the coupling ring 19 so as to transmit power (it is also possible to directly connect the pinion shaft 10 and the output shaft 60).

In the planetary gear mechanism 20, the sun gear 21 is integrally formed with a shaft 90 that is rotatably supported by the carrier 22 via a bush 71 and rotatably supported by the housing 80 via the bush 72. The carrier 22 is rotatably supported by a housing 80 via a bush 73, and is connected to a planetary gear 25 (which meshes with the sun gear 21 and ring gear 23) via a support shaft 24 (which is press-fitted to the carrier 22). ) is rotatably supported. In addition, the carrier 22 is a snap spring 2.
The position is determined by 6. Further, the ring gear 23 is rotatably supported on the carrier 22 via bushes 74 and 75, and a wheel 32 is integrally formed on the outer periphery of the ring gear 23. The wheel 32 constitutes the worm gear 30 with the worm 31 which is assembled to be integrally rotatable on the rotating shaft 41a of the first electric motor 41, and the power transmission efficiency from the wheel 32 to the worm 31 is zero ( The worm 31 cannot be rotated by the wheel 32).

The first electric motor 41 is energized by a control device (not shown), and is attached to the housing 80 through its case 41b. Moreover, as shown in FIG. Adjustment bolt 8
2 (fixed by a lock nut 83), and the worm 31 is fixed to the outer periphery of the worm 31 by a pin 43 so as to be rotatable therewith.

On the other hand, like the first electric motor 41, the second electric motor 42 is energized under control by a control device (not shown), and is attached to the housing 80 through its case 42b. The rotating shaft 42b of the second electric motor 42 is rotatably supported by a housing 80 via a bush 77 at its tip, and is fixed by an adjusting bolt 85 (lock nut 86) via a ball 84. ), and a worm 5 is attached to its outer periphery.
1 is fixed by a pin 44 so as to be integrally rotatable. The worm 51 and the wheel 52 formed integrally with the shaft 90 formed by the sun gear 21 constitute the worm gear 50, and the power transmission efficiency from the wheel 52 to the worm 51 becomes zero (the wheel 52 Therefore, the worm 51 cannot be rotated.

In this embodiment configured as described above, the worm gear 3 is activated by energizing the first electric motor 41.
When the ring gear 23 of the planetary gear mechanism 20 is rotated via the second electric motor 42 , the rotational force is transmitted to each other element of the planetary gear mechanism 20 .
However, the sun gear 21 of the planetary gear mechanism 20 and the second electric motor 42
Since the power transmission efficiency from the wheel 52 to the worm 51 in the worm gear 50 interposed between the rotating shaft 42a of the planetary gear mechanism 20 is assumed to be zero,
Each member from the sun gear 21 to the rotating shaft 42a of the second electric motor 42 is not rotated and functions as a reaction force member. Therefore, by energizing the first electric motor 41, the output shaft 60 connected to the carrier 22 of the planetary gear mechanism 20 is rotated, and the output shaft 60 rotationally drives the pinion shaft 10 that sets the steering angle ratio. Can be done.

On the other hand, when the second electric motor 42 is energized to rotate the sun gear 21 of the planetary gear mechanism 20 via the worm gear 50, the rotational force is transmitted to each other element of the planetary gear mechanism 20, and the rotational force is transmitted to each other element of the planetary gear mechanism 20. Although an attempt is made to rotate the rotating shaft 41a, the worm 3 is rotated from the wheel 32 at the worm gear 30 interposed between the ring gear 23 of the planetary gear mechanism 20 and the rotating shaft 41a of the first electric motor 41.
Since the power transmission efficiency to the first electric motor 1 is zero, each member from the ring gear 23 of the planetary gear mechanism 20 to the rotating shaft 41a of the first electric motor 41 is not rotated and functions as a reaction force member. Therefore, by energizing the second electric motor 42, the output shaft 60 connected to the carrier 22 of the planetary gear mechanism 20 is rotated, and the output shaft 60 rotationally drives the pinion shaft 10 that sets the steering angle ratio. You can also do it.

As described above, in this embodiment, in normal times (when the electric motors 41 and 42 are normal), the pinion shaft 10 can be rotationally driven by energizing the first electric motor 41 to set the steering angle ratio to the set value. Furthermore, when the first electric motor 41 fails, the second electric motor 42 is energized to rotate the pinion shaft 10 and set the steering angle ratio to the set value. Therefore, the reliability of the system can be improved.
Further, since the planetary gear mechanism 20 and the worm gears 30, 50 are adopted as a mechanism for rotating the output shaft 60 by energizing the first or second electric motors 41, 42, the driving means B is a mechanism for rotating the output shaft 60 by energizing the first or second electric motors 41, 42.
1 and 42, it is compact and can ensure good vehicle mountability.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the driving means in the electric steering angle ratio setting device of the rear wheel steering device according to the present invention, FIG. 2 is a cross-sectional view taken along the line - in FIG. 1, and FIG. FIG. 2 is a partially cutaway plan view showing the entire wheel steering device. Explanation of symbols, 10...Pinion shaft (rotated body), 20...Planetary gear mechanism, 21...Sun gear, 22...Carrier, 23...Ring gear, 3
0...First worm gear, 31... Worm, 32... Wheel, 41... First electric motor, 41a... Rotating shaft, 42... Second electric motor, 42a... Rotating shaft, 50... Second worm gear, 51...Worm, 52...Wheel, 6
0...Output shaft, A...Electric steering angle ratio setting device, B
...Drive means, WF...front wheel, WR...rear wheel.

Claims (1)

[Scope of utility model registration request] In a rear wheel steering device for a front and rear wheel steered vehicle comprising an electric steering angle ratio setting device for setting a steering angle ratio between front wheels and rear wheels, the drive means for the electric steering angle ratio setting device includes a sun gear, a carrier, and a sun gear. a planetary gear mechanism including three elements of a ring gear; a first electric motor connected to one element of the planetary gear mechanism via a first worm gear whose power transmission efficiency from the wheel to the worm is zero; a second electric motor connected to other elements of the planetary gear mechanism via a second worm gear with zero power transmission efficiency from the wheel to the worm; and an output shaft connected to the remaining elements of the planetary gear mechanism. The front and rear wheels are equipped with a drive means configured to rotationally drive a rotated body that sets the steering angle ratio at the output shaft by energizing the first or second electric motor. Rear wheel steering device for steered vehicles.