JPH07186978A - Rear-wheel steering gear - Google Patents

Abstract

PURPOSE:To secure a rear-wheel steering gear that dispenses with an expensive hypoid gear by installing a second planetary gear, integrally rotating with a first planetary gear, in another surface of a carrier installed in a connecting means free of rotation and also a second ring gear integrally rotating with this connecting means and engaging the second planetary gear, respectively. CONSTITUTION:A first planetary gear 15 is installed in one side surface of a carrier 13, namely, at the side of an output shaft, and a second planetary gear 17 is installed in the opposite surface. In this case, however, since a shaft 19 is installed in the second planetary gear 17, this shaft 19 is pierced through the carrier 13, and the first planetary gear 15 is clamped to this pierce-through end, both these first and second planetary gear 15 and 17 are always rotated as one body. In addition, a holding member 25 is clamped to a pinion shaft 9, while a second ring rear 27 is secured to this holding member 25. In succession, the second planetary gear 17 installed int the carrier 13 free of rotation is engaged with the second ring gear 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel steering device that steers rear wheels using the driving force of an electric motor.

[0002]

2. Description of the Related Art As an apparatus of this type, Japanese Patent Laid-Open No. 4-866
The device described in Japanese Patent Publication No. 7 is conventionally known. In this conventional device, the driving force of the electric motor is transmitted to the rack shaft by using a hypoid gear. The reason why the hypoid gear is used is to maintain so-called irreversibility so that the rear wheel does not easily change its direction when an impact force acts on the rear wheel.

[0003]

The greatest drawback of the above-mentioned conventional device is that the hypoid gear is very expensive. Therefore, there is a problem that the entire apparatus becomes expensive. An object of the present invention is to provide an inexpensive rear wheel steering system.

[0004]

A first invention is a gear box, an electric motor connected to the gear box and having an output shaft projecting into the gear box, a rod linked to a rear wheel, and this rod. Linking means for moving the horizontal direction, and a carrier rotatably provided on the linking means,
A first planetary gear rotatably provided on one surface of the carrier; a second planetary gear provided on the other surface of the carrier and rotating integrally with the first planetary gear; and fixed to the output shaft of the electric motor. A sun gear that meshes with the first planetary gear, and a first gear that meshes with the first planetary gear and is fixed in the gear box.
It is characterized in that it comprises a ring gear and a second ring gear that rotates integrally with the above-mentioned linking means and that meshes with the second planetary gear. A second invention is a gear box, a rod provided in the gear box and linked to a rear wheel, a linking unit for moving the rod in a horizontal direction, and a carrier rotatably provided on the linking unit. A first planetary gear rotatably provided on one surface of this carrier, a second planetary gear provided on the other surface of this carrier and rotating integrally with the first planetary gear, and a first planetary gear and a gear box. It is characterized in that it comprises a first ring gear fixed therein, a second ring gear that rotates integrally with the linking means and meshes with a second planetary gear, and an electric motor that applies a rotational force to the carrier.

[0005]

According to the first aspect of the invention, when the electric motor rotates, the sun gear rotates and at the same time meshes with the sun gear.
The planet gear meshes with the first ring gear and revolves while rotating on its axis. By the revolution of the first planetary gear, the carrier also rotates, and further, the rotation of the first planetary gear causes the second planetary gear to rotate. When the second planetary gear revolves around its own axis in this manner, the second ring gear also rotates. When the second ring gear rotates, the linkage means that rotates together with it also rotates, so that the rod linked to the rear wheels moves accordingly, and the rear wheels are steered in the desired direction. When an impact force acts on one rear wheel and the rod moves, the following occurs. That is, when the rod moves, a rotational force acts on the linking means. This rotational force also acts on the second ring gear and the second planetary gear. However, since the carrier supporting the second planetary gear is rotatable with respect to the linking means, the second planetary gear does not rotate but the second planetary gear rotates in order to rotate integrally with the carrier. do not do. Further, since the second planetary gear does not rotate, the first planetary gear also does not rotate. However, since the revolving force of the carrier acts on this first planetary gear, since the first ring gear is fixed to the gear box, the revolution of the first planetary gear is also prevented. After all, even if a force is applied from the rear wheel side, the linkage means does not rotate, and so-called irreversibility is maintained.

A second aspect of the invention is to drive an electric motor,
Since the carrier rotates, the first and second planetary gears revolve around their own axes. As a result, the second ring gear rotates to rotate the linking means, so that the rod moves to steer the rear wheels, as in the first invention. Further, when an impact force acts on the rear wheel and the rod moves, the following occurs. That is, when the rod moves, the rotational force acts on the pinion shaft. This rotational force also acts on the second ring gear and the second planetary gear. But the second
Since the carrier supporting the planetary gear is rotatable with respect to the linking means, the second planetary gear does not rotate, but the second planetary gear does not rotate, so that the second planetary gear does not rotate. Also, since this second planetary gear does not rotate,
The first planetary gear also does not rotate. However, although the revolving force of the carrier acts on the first planetary gear, the revolving of the first planetary gear is also prevented because the first ring gear is fixed to the gear box. After all, even if a force is applied from the rear wheel side, the linkage means does not rotate, and so-called irreversibility is maintained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment shown in FIGS. 1 and 2, an electric motor 3 is connected to a gear box 1 and an output shaft 5 of the electric motor 3 is projected into the gear box 1. . Further, the gear box 1 is provided with a rack shaft 7 on which a rack 6 is formed, and both ends of the rack shaft 7 are linked to a rear wheel (not shown). Therefore, the rack shaft 7 constitutes the rod in the present invention. The pinion 11 of the pinion shaft 9 is engaged with the rack 6 formed on the rack shaft 7. The inner end of the pinion shaft 9 faces the output shaft 5 of the electric motor 3, and the carrier 13 is rotatably provided at the facing end. The first planetary gear 15 is provided on one surface of the carrier 13, that is, on the output shaft 5 side,
A second planetary gear 17 is provided on the opposite surface. However,
Since the shaft 19 is provided in the second planetary gear 17, the shaft 19 is penetrated through the carrier 13, and the first planetary gear 15 is fixed to the penetrating end, the first and second planetary gears 15 and 17 are always integrated. Rotate to.

The first planetary gear 15 meshes with the sun gear 21 fixed to the output shaft 5 of the electric motor 3 and also meshes with the first ring gear 23 fixed to the gear box 1. A holding member 25 is fixed to the pinion shaft 9 and the holding member 2
The second ring gear 27 is fixed to 5. Then, the second planetary gear 17 rotatably provided on the carrier is meshed with the second ring gear 27. Reference numeral 29 in the drawing is a sensor that detects the amount of movement of the rack shaft 7, that is, the turning angle of the rear wheels. The rack shaft 7 constitutes the rod of the present invention, while the holding member 25 and the pinion shaft 9 constitute the linking means of the present invention. Next, the operation of the first embodiment will be described. Now, when the electric motor 3 is rotated in a desired direction and the sun gear 21 is rotated, the first planetary gear 15 is rotated accordingly. On the other hand, since the first ring gear 23 is fixed to the gear box 1, the first planetary gear 15 revolves around the sun gear while rotating on its axis.

By the rotation and revolution of the first planetary gear 15, the second planetary gear 17 also rotates and revolves, and
The ring gear 27 is rotated. When the second ring gear 27 rotates, the holding member 25 and the pinion 11 formed on the pinion shaft 9 also rotate accordingly, so that the rack 6
The rack shaft 7, which is engaged with the pinion 11, moves in the horizontal direction. By the movement of the rack shaft 7, the rear wheels linked to both sides thereof are steered. When the rack shaft 7 is about to move due to the impact on the rear wheel side, the moving force acts on the pinion shaft 9 as a rotational force. This rotational force is also transmitted to the second planetary gear 17 via the holding member 25 and the second ring gear 27. However, in order for the second planetary gear 17 to rotate by receiving the rotational force of the second ring gear 27, the carrier 13 must be stopped, but the carrier 13 is rotatable with respect to the pinion shaft 9. .

Therefore, the second planetary gear 17 does not rotate, and naturally, the first planetary gear 15 also does not rotate. Moreover, since the first ring gear 23 that meshes with the first planetary gear 15 is fixed to the gear box 1, the first planetary gear 15 does not revolve. Therefore, the moving force of the rack shaft 7 is not transmitted, so that the so-called irreversibility is maintained, and the rear wheel is prevented from inadvertently changing its direction by the action of the external force. The steering angle of the rear wheels is measured by the sensor 2
9 and is fed back to the electric motor 3. Further, in this first embodiment, the pinion shaft 9 and the pinion 11
The rack 6 and the rack 6 constitute the linking means, but it goes without saying that the linking means using offset pins may be used as in the conventional case. In short, the linking means is not particularly limited as long as it is a mechanism capable of transmitting the rotational force of the second ring gear 27 to the rack shaft 7 (rod).

In the second embodiment shown in FIG. 3, the first ring gear 23 fixed to the gear box 1, the rack shaft 7 on which the rack 6 is formed, and the pinion shaft 9 on which the pinion 11 is formed.
And a holding member 25 that rotates integrally with the pinion shaft 9,
The second ring gear 27 fixed to the holding member 25 is the same as that of the first embodiment. In the second embodiment, the carrier 31 is rotatably attached to the inner end of the pinion shaft 9. Carrier 3 made in this way
A bevel gear 33 is formed on the outer circumference of the No. 1 and a bevel pinion 39 fixed to an output shaft 37 of an electric motor 35 is engaged with the bevel gear 33. The first planetary gear 15 and the second planetary gear 17 are provided on the carrier 31 as in the first embodiment.

Next, the operation of the second embodiment will be described.
When the electric motor 35 is driven and the bevel pinion 39 rotates, the carrier 31 rotates. With the rotation of the carrier 31, the second planetary gear 17 revolves around its own axis, so that the second ring gear 27 also rotates. And
The rotation of the second ring gear 27 is transmitted to the rack shaft 7 via the holding member 25, the pinion shaft 9, the pinion 11 and the rack 6, so that the rack shaft 7 moves in the horizontal direction and the rear wheel is expected. Is steered in the direction of. Also, when the rack shaft 7 is about to move due to the impact on the rear wheel side,
The moving force acts on the pinion shaft 9 as a rotating force. This rotational force is also transmitted to the second planetary gear 17 via the holding member 25 and the second ring gear 27. However, in order for the second planetary gear 17 to rotate by receiving the rotational force of the second ring gear 27, the carrier 31 must be stopped, but the carrier 31 is rotatable with respect to the pinion shaft 9. .

Therefore, the second planetary gear 17 does not rotate, and naturally, the first planetary gear 15 also does not rotate. Moreover, since the first ring gear 23 that meshes with the first planetary gear 15 is fixed to the gear box 1, the first planetary gear 15 does not revolve. Therefore, the moving force of the rack shaft 7 is not transmitted, so that the so-called irreversibility is maintained, and the rear wheel is prevented from inadvertently changing its direction by the action of the external force. Incidentally, also in the case of the second embodiment,
Although the linking means is composed of the pinion shaft 9, the pinion 11 and the rack 6, for example, the linking means using an offset pin may be used as in the prior art, which is similar to the first embodiment.

[0014]

According to the rear wheel steering system of the present invention, it is not necessary to use an expensive hypoid gear as in the prior art, so that the cost of the entire system can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is a front view of the first embodiment.

FIG. 3 is a sectional view of a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gear box 3 Electric motor 5 Output shaft 6 Rack 7 constituting linking means 7 Rack shaft constituting rod 9 Pinion shaft 11 constituting linking means Pinion 13 constituting linking means 13 Carrier 15 First planetary gear 17 Second planetary gear 21 sun gear 23 first ring gear 25 holding member constituting the linking means 27 second ring gear 31 carrier

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Naruse 2548 Tsuchida, Kani City, Gifu Prefecture Kayaba Industry Co., Ltd.Gifu North Factory (72) Inventor Shiro Suo 2548, Tsuchida, Kani City, Gifu Prefecture Kayaba Industry Co., Ltd.Gifu Kita In the factory (72) Inventor Masafumi Ohira 2548 Tsuchida, Kani City, Gifu Prefecture Kaiba Industrial Co., Ltd. Gifu North Factory

Claims (2)

[Claims] 1. A gear box, an electric motor connected to the gear box and having an output shaft projecting into the gear box, a rod linked to a rear wheel, and linking means for moving the rod in a horizontal direction. A carrier rotatably provided on the linking means, a first planetary gear rotatably provided on one surface of the carrier, and a second planetary gear provided on the other surface of the carrier and integrally rotating with the first planetary gear. A planetary gear, a sun gear fixed to the output shaft of the electric motor and meshing with the first planetary gear, a first ring gear meshing with the first planetary gear and fixed in the gearbox, and integrally rotating with the linkage means and A rear wheel steering system including a second planetary gear and a second ring gear that meshes with the second planetary gear. 2. A gearbox, a rod provided in the gearbox and linked to a rear wheel, a linking means for moving the rod in a horizontal direction, a carrier rotatably mounted on the linking means, A first planetary gear rotatably provided on one surface of the carrier, and a second planetary gear provided on the other surface of the carrier and integrally rotating with the first planetary gear,
From a first ring gear that meshes with the first planetary gear and is fixed in the gear box, a second ring gear that rotates integrally with the linkage means and meshes with the second planetary gear, and an electric motor that imparts rotational force to the carrier. Rear wheel steering system.