JPS63258272A - Rear wheel steering gear for vehicle - Google Patents

Abstract

PURPOSE:To prevent an operating rod from damages by disposing the axis of a drive pinion above the axis of a ring gear, forming a space below the front portion of an operative device and providing a rear wheel operating rod in the space. CONSTITUTION:A differential gear 38 has the axis of a drive pinion 41 offset above a ring gear 42 and a drive pinion shaft 40 disposed above a differential housing 43 to form one of a reverse offset type. By disposing the drive shaft 40 above the differential housing 43 is formed a space 44 below said shaft 40, and in the space 44 is disposed a rear wheel operating rod 11 for a rear wheel steering mechanism 7. Thus, since the operating rod 11 is disposed in the space 44, the operating rod 11 is prevented from the influence of road surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rear wheel steering device for a vehicle equipped with a rear wheel operating rod for steering the rear wheels, and in particular for transmitting the driving force of a propeller shaft to the rear wheels. The present invention relates to a rear wheel steering device for a vehicle having a differential device.

(Prior art) Conventionally, as a rear wheel steering device, for example,
As shown in Publication No. 80, the relative lateral displacement that occurs between the upper and lower sides of the rear suspension leaf spring when the vehicle turns is transmitted to the tie rod (rear wheel operating rod), and the tie rod is moved from side to side. It is known that the left and right rear wheels are steered by moving them. Furthermore, as shown in Japanese Patent Application Laid-Open No. 59-77968, a rear wheel steering device is known which is equipped with a rear wheel operating rod that changes the steering angle of the rear wheels at a predetermined steering ratio in response to the steering of the front wheels. It is being In these rear wheel steering devices, when the rear wheel operating rod is disposed behind the rear wheel axle, the rear wheel operating rod is close to the exhaust system silencer and the fuel tank, and the operating rod and its drive mechanism are In addition to being exposed to the heat r411 of the silencer, the installation space for the fuel tank is restricted due to the presence of the rear wheel operating rod, resulting in a reduction in tank capacity.

In addition, in order to prevent the above-mentioned thermal effects and to ensure sufficient fuel tank capacity, when the above-mentioned rear wheel operating rod is disposed on the front side of the rear wheel axle, the above-mentioned rear wheel operating rod may be Must be installed below the propeller shaft. For this reason, in a vehicle in which a differential device is provided on the rear wheels, as shown in FIG. 5, the rear wheel operating rod 11' must be arranged so as to avoid the differential device 38'.
Accordingly, the distance from the road surface to the operating rod 11', that is, the installation height 1'' of the operating rod 11', is reduced, and there is a problem that the rear wheel operating rod 11' and its drive mechanism are easily affected by the road surface. Ta.

(Object of the Invention) The present defense has been made to solve the above problem, and the rear wheel operating rod is disposed on the side of the rear wheel axle in order to avoid the influence of the silencer of the exhaust system. At the same time, there is a difference for the rear wheel! It is an object of the present invention to prevent the installation height of a rear wheel operating rod from becoming low in a rear wheel steering device for a vehicle provided with an II device.

(Structure of the Invention) The present invention provides a rear wheel steering device for a vehicle that includes a differential device that transmits the driving force of a propeller shaft to the rear wheels, and a rear wheel operating rod that steers the rear wheels. The axis of the drive pinion installed in the differential gear is offset above the axis of the ring gear, and the rear wheel operating rod is placed in the space formed below the front of the differential gear. be.

According to the above configuration, the axis of the drive pinion is disposed above the axis of the ring gear, and the propeller shaft is offset to the upper side of the differential, so that it is formed below the front of the differential #a position. The rear wheel operating rod will be installed using the space provided.

(Embodiment) FIG. 1 shows the overall configuration of a vehicle equipped with a rear wheel steering device according to an embodiment of the present invention, in which reference numeral 1 denotes a front wheel steering jaM4 for steering left and right front wheels 2L and 2R; The front wheel steering mechanism 1 includes a steering handle 3, a rack and binion mechanism 4 that converts the rotational motion of the steering handle 3 into linear motion, and a front wheel steering mechanism 1 that directs the power of the rack and binion mechanism 4 to the front wheels 2.
It consists of left and right tie rods 5.5 and knuckle arms 6.6 that transmit power to 1.2R and steer them left and right.

7 is a rear wheel steering mechanism that steers the left and right rear wheels 81, 8R, and this rear wheel steering mechanism 7 has both ends of the left and right rear wheels 81.
,． Tie rod 9.9 and knuckle arm 10 on 8R
．． Rear wheel operation 1 extending in the vehicle width direction connected via 10
It is equipped with Kotsuto 11.

A rack 12 is formed on this rear wheel operating rod 11, and a binion 13 that meshes with this rack 12 is connected to a pulse motor 1.
4 makes a pair of double in5. i6 and pinion shaft 17
The pulse motor 14 is rotated through the
The rear wheels 81, 8R are configured to be steered left and right in accordance with the rotation direction and amount of rotation.

Further, a power cylinder 18 is connected to the rear wheel operating rod 11, which uses the rod 11 as an operating rod. This power cylinder 18 has a left-turning hydraulic chamber 18b and a right-turning hydraulic chamber 18c, which are partitioned in the width direction by a piston 18a fixed to the rear wheel operating rod 11. Control valves 2 18b and 18c control oil supply direction and oil pressure to the power cylinder 18 via hydraulic passages 1a and 19b, respectively.
A hydraulic pump 23 is connected to this control valve 20 via an oil supply passage 21 and an oil return passage 22, and this hydraulic pump 23 is rotationally driven by a motor 24. The control valve 20 detects the rotational direction of the pinion shaft 17 and communicates the oil supply passage 21 with the left-turn hydraulic pressure v18b when the rear wheels 8L and 8R are steered to the left (counterclockwise in the figure). And right diversion hydraulic chamber 1
8c is communicated with the oil return path 22, while the rear wheels 8 are connected in the opposite state to the above when the rear wheel 8R is turned to the right (clockwise in the figure), and at the same time, the hydraulic pressure from the hydraulic pump 23 is connected. The pressure is reduced according to the rotational force of the pinion shaft 17, and the pulse motor 14 moves the rear wheel operating rod 11 in the axial direction (vehicle width When the rear wheel operating rod 11 is moved in this direction, pressure oil is supplied to the power cylinder 18 to assist the movement of the rear wheel operating rod 11.

The operation of the pulse motor 14 and the drive motor 24 of the hydraulic pump 23 is controlled by a control signal output from a controller 25 that is a control section of the rear wheel steering mechanism 7. The front wheel steering mechanism 1 to the rollers 25 are
A steering angle signal from a steering angle sensor 26 that detects the front wheel turning angle from the amount of steering of the steering wheel 3, etc., and a vehicle speed signal from a vehicle speed sensor 27 that detects vehicle speed are respectively input, and the selection switch 28 and two battery power sources are connected.

As shown in FIG. 2, the controller 25 receives the steering angle signal from the steering angle sensor 26 and the vehicle speed signal from the vehicle speed sensor 27, and determines the front wheel steering angle from the steering ratio characteristic stored in the characteristic storage section 30. and a target steering angle calculation unit 31 that calculates a target steering angle of the rear wheels corresponding to the vehicle speed, and a pulse generator that outputs a pulse signal corresponding to the target steering angle calculated by the target steering angle calculation unit 31. 32, and the pulse motor 1 receives the pulse signal from the pulse generator 32.
4 and a driver 33 that converts the drive pulse signal into a drive pulse signal that drives the drive motor 24 of the hydraulic pump 23, whereby the ratio of the rear wheel steering angle to the front wheel steering angle (steering ratio) is set to a predetermined steering ratio characteristic. Accordingly, a steering ratio variable means 34 is configured to control the pulse motor 14 and the drive motor 24 of the hydraulic pump 23 so that the rear wheel steering angle becomes the target steering angle.

As shown in FIG. 3, the steering ratio characteristics stored in the characteristic storage section 30 are such that as the medium speed improves from low speed to high speed, the steering ratio k becomes large in the negative phase region in the negative direction. The above steering ratio k changes to the same phase in the positive direction in the medium speed range, and remains the same in the high speed range (at a3 in the ff phase region, the steering ratio k increases as the vehicle speed increases). It is set to be.

Further, between the rear wheels 81.8R, the driving force of a propeller shaft 36 driven by an engine (not shown) is transmitted to a rear wheel shaft 3.
7 is provided. As shown in FIG. 4, the differential device 38 includes a drive pinion shaft 40 connected to the propeller shaft 36 via three connecting flanges, and a drive pinion 41 attached to the tip of the drive pinion shaft 40. and,
It has a pair of ring gears 42 driven by this drive pinion 41.

The differential device 38 is formed in a so-called reverse offset type in which the axial center of the drive pinion 41 is offset above the ring gear 42 and the drive pinion shaft 40 is disposed above the differential housing 43. By disposing the drive pinion shaft 40 above the differential housing 43, the rear wheel is placed in a space 44 below the differential gear 38, which is formed in the space below the differential housing 43, that is, in front of the rear wheel shaft 37. A rear wheel operating a-rad 11 of the wheel steering mechanism 7 is provided.

In this way, the axis of the drive pinion 41 is connected to the ring gear 4.
The rear wheel operating rod 11 is installed by using the space 44 formed by offsetting the rear end of the propeller shaft 36 upward compared to the normal offset state. Therefore, the rear wheel operating rod 11 can be disposed in front of the rear wheel shaft 37 without reducing the installation height 1 of the rear wheel operating rod 11.

Therefore, the rear wheel operating rod 11 and the like can be prevented from being affected by the road surface, etc., and the rear wheel operating rod 11
If the rear wheel steering mechanism 7 is placed behind the rear wheel shaft 37, the rear wheel steering mechanism 7 may be thermally affected by the silencer of the exhaust system,
The presence of the rear wheel operating rod 11 can prevent the capacity of the fuel tank from decreasing.

In the above embodiment, a rear wheel steering device that constitutes a part of a four-wheel steering device of a vehicle has been described, but the present invention also applies to a rear wheel steering device that steers the rear wheels independently of front wheel steering. can be applied.

(Effects of the Invention) As explained above, the present invention provides an arrangement in which the axis of the drive pinion provided in the differential gear for ring erosion is located 60 degrees from the axis of the ring gear.
By placing the rear wheel operating rod above, the space created below the surface of the differential gear is used to install the rear wheel operating rod. A wheel operating rod can be arranged in front of the rear wheel axle.

Therefore, the rear wheel operating rod and its drive mechanism can be prevented from being affected by the road surface, and the rear wheel steering mechanism can be prevented from being close to the exhaust system muffler and being affected by its heat, and the rear wheel operating rod can be prevented from being affected by its heat. Therefore, it is possible to effectively prevent the capacity of the fuel tank from decreasing.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing an embodiment of the present invention, Fig. 2 is a block diagram of the controller, Fig. 3 is a characteristic diagram of vehicle speed and steering ratio, and Fig. 4 is a sectional view showing the main parts of the present invention. , FIG. 5 is a sectional view showing a conventional example. 8L, 8R...Rear wheel, 11...Rear wheel operation rod, 3
6... propeller shaft, 38... differential gear, 41
... Drive pinion, 42 ... Ring gear, 44
...Space department. Patent applicant Mazda Co., Ltd. Agent Patent attorney Etsushi Kotani Patent attorney Chief 1) 1 Patent attorney Yasuo Itaya Figure 2

Claims (1)

[Claims] 1. A rear wheel steering device for a vehicle comprising a differential device that transmits the driving force of a propeller shaft to the rear wheels, and a rear wheel operating rod that steers the rear wheels. A rear wheel of a vehicle characterized in that the axis of the drive pinion is offset above the axis of the ring gear, and a rear wheel operating rod is disposed in a space formed below the front of the differential. Steering device.