JPH037267Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a steering regulating device in a rear wheel steering device that uses hydraulic pressure to steer the left and right rear wheels of a vehicle.

(Prior Art) Conventionally, as one type of rear wheel steering device, for example, Japanese Patent Laid-Open No. 11173/1983, Japanese Patent Laid-Open No. 150066/1983,
Japanese Utility Model Publication No. 57-19172 and other publications propose a system in which a hydraulic cylinder drives a rear wheel steering link mechanism to steer the left and right rear wheels.

(Problem to be solved by the invention) By the way, in the conventional device described above, the amount of oil supplied to the hydraulic cylinder is controlled only by the hydraulic control device, so the rear wheel steering by the hydraulic control device is difficult. When the vehicle does not operate normally, it is desirable that the left and right rear wheels return to and maintain a neutral state (a straight-ahead state where the steering angle is zero).

The present invention was developed in response to these demands, and its main purpose is to forcibly return and maintain the left and right rear wheels in a neutral state when the rear wheel steering by the hydraulic control device does not operate normally. It's about doing.

(Means for Solving the Problem) In order to achieve the above object, the present invention includes a hydraulic supply device, a hydraulic cylinder that drives a rear wheel steering link mechanism, and a hydraulic cylinder that drives a rear wheel steering link mechanism. A rear wheel steering device that is equipped with a hydraulic control device that controls the amount of oil supplied to steer the left and right rear wheels includes: a connecting member that connects the left and right rear wheels and is displaced in the axial direction as the wheels are steered; a displacement member provided on the member and displaced together with the connecting member; a cylinder member provided along the displacement direction of the displacement member; and a cylinder member slidably provided on the cylinder member with the displacement member sandwiched therebetween. and determining whether a pair of piston members defining a pair of hydraulic chambers on both sides opposite to a surface facing the displacement member and rear wheel steering by the hydraulic control device are operating normally. A control device outputs a control signal, and the operation is controlled by the control signal from the control device, and when the rear wheel steering by the hydraulic control device operates normally, the hydraulic pressure supply to the pair of hydraulic chambers is cut off. A switching means is provided which connects both of the pair of hydraulic chambers to the hydraulic pressure supply device and bleeds the hydraulic pressure in the hydraulic cylinder when the rear wheel steering by the hydraulic control device does not operate normally.

(Operation and Effect of the Invention) In the present invention, when the rear wheel steering by the hydraulic control device operates normally, the hydraulic pressure supply to the pair of hydraulic chambers is cut off by the switching valve means. Pressure oil is not supplied and the displacement member is not clamped by the piston member.
Therefore, the displacement member can move freely, and the hydraulic cylinder operates according to the amount of oil supplied by the operation of the hydraulic control device, and the rear wheel steering link mechanism is driven in accordance with this operation. The left and right rear wheels are steered.

Therefore, when the rear wheel steering by the hydraulic control device does not operate normally, the hydraulic pressure in the hydraulic cylinder is bled by the switching valve means, and the pair of hydraulic chambers are connected to the hydraulic pressure supply device, and the hydraulic pressure is connected to the hydraulic pressure supply device. Since hydraulic pressure is supplied, the pair of piston members move toward the displacement member, forcibly moving the displacement member to its neutral position and clamping the displacement member. Therefore, the connecting member that is displaced together with the displacement member is also held at its neutral position, and the left and right rear wheels connected thereto are held in a neutral state.

(Example) An example of the present invention will be described below based on the drawings.

Figure 1 shows the schematic configuration of a front and rear wheel steered vehicle to which the present invention is applied.
The rear wheels RW, RW are configured to be steered by a rear wheel steering link mechanism 10. The rear wheel steering link mechanism 10 is composed of knuckle arms 11, 11, tie rods 12, 12, and a connecting rod 13, and includes a hydraulic cylinder 2.
0.

The hydraulic cylinder 20 includes a cylinder body 21 coaxially provided on the connecting rod 13, and a piston 22 fixed to the center of the connecting rod 13 to partition the inside of the cylinder body 21 into left and right main oil chambers R1 and R2. , a hydraulic pump P and a reservoir tank T, both main oil chambers R1 and R2 of the cylinder body 21 are driven by an engine (or electric motor) via a servo valve 30 whose operation is controlled by an electric control device 40.
It is connected to the.

The electric control device 40 is a known device, and operates under conditions set in advance based on a signal from a front wheel steering angle sensor 41 that detects the steering angles of the front wheels FW, FW by the rotation of a steering shaft 51 rotated by a steering wheel 50. The servo valve 30 is controlled to set the displacement of the connecting rod 13 to a set value. Incidentally, the displacement of the connecting rod 13 is detected by the potentiometer 42 and feedback control is performed.

In this embodiment, as shown in FIGS. 1 and 2, floating pistons 61 and 62 are arranged on both sides of the piston 22 in the cylinder body 21 in a liquid-tight manner and slidable in the axial direction. It is set up. Each of the floating pistons 61 and 62 forms an auxiliary oil chamber R3 and R4 with the cylinder body 21, and both of these auxiliary oil chambers R3 and R4 are connected to the hydraulic pump P via a first on-off valve 63. In addition, the cylinder body 2
A pair of ports 65, 66 are formed in the center of the cylinder body 1, and both ports 65, 66 are connected to the main oil chambers R1, R2 near both sides of the piston 22 when the piston 22 is located approximately at the center of the cylinder body 21. Each opens (see Figure 3). In addition, both ports 65,
66 is the reservoir tank T via the second on-off valve 64
It is connected to the. Both on-off valves 63 and 64 are solenoid valves that close when not energized, and the control device 7
0, the operation is controlled by the control device 70
It is configured to open in response to a signal from. The control device 70 is configured independently of the electric control device 40, and adjusts the rear wheel steering angle to the front wheel FW based on signals from the front wheel steering angle sensor 41 and the potentiometer 42.
When the rear wheel steering angle is not properly linked to the steering operation of the front wheels FW, a signal is sent to both on-off valves 63 and 64, which are normally closed.

In the rear wheel steering regulating device configured as described above, when the hydraulic cylinder 20 is operating properly and the rear wheel steering angle is appropriately linked to the front wheel FW steering operation, the control device 70 determines this. Therefore, no signal is sent to both on-off valves 63 and 64. Therefore, both the on-off valves 63 and 64 are closed without opening, and the hydraulic cylinder 20 operates normally, and the auxiliary oil chamber R
3. Pressure oil is not supplied into R4, and both floating pistons 61 and 62 are held at the positions shown in the figure, and the piston 2
There is no need to pinch 2. Therefore, the piston 22 can move freely, and the hydraulic cylinder 20 is operated in response to the operation of the servo valve 30, and the rear wheel steering link mechanism 10 is driven in accordance with the operation of the hydraulic cylinder 20 to rotate the left and right wheels. Rear wheels RW and RW are steered.

However, when the hydraulic cylinder 20 does not operate properly and the rear wheel steering angle is no longer properly linked to the front wheel FW steering operation, the control device 70 determines this and sends a signal to both on-off valves 63 and 64. . Therefore, both the on-off valves 63 and 64 are opened, and pressure oil from the hydraulic pump P is supplied into both the auxiliary oil chambers R3 and R4, and
The hydraulic oil in both main oil chambers R1 and R2 is connected to both ports 65,
66 to the reservoir tank T (hydraulic pressure is bled), both floating pistons 61 and 62 move toward the approximate center of the cylinder body 21, and the piston 2
2 is held at approximately the center of the cylinder body 21 (see FIG. 3). Therefore, the rear wheel steering link mechanism 10 is held in its neutral state, and the rear wheel steering link mechanism 10 is maintained in its neutral state.
RW and RW are maintained in a neutral state.

(Modification) In the above embodiment, an example was explained in which the steering restriction device according to the present invention was integrally assembled to the rear wheel steering link mechanism 10 and the hydraulic cylinder 20 that constitute the rear wheel steering device. The steering restriction device according to the invention can also be implemented by being configured separately from the rear wheel steering link mechanism 10 and the hydraulic cylinder 20 that constitute the rear wheel steering device. In addition, in the above embodiment, both auxiliary oil chambers R3 and R4
Although it is connected to the hydraulic pump P via the first on-off valve 63, it is also possible to implement the present invention by connecting it to an accumulator in which pressure is stored in advance by the hydraulic pump P.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention;
FIG. 2 is an enlarged sectional view of the hydraulic cylinder shown in FIG. 1, and FIG. 3 is an enlarged sectional view of the hydraulic cylinder with both floating pistons in operation. Explanation of symbols, 10... Rear wheel steering link mechanism, 13... Connection rod (connection member), 20
... Hydraulic cylinder, 21 ... Cylinder body (cylinder member), 22 ... Piston (displacement member), 3
0, 40... Servo valve, electric control device (hydraulic control device), 61, 62... Floating piston (pair of piston members), 63, 64... Opening/closing valve (switching valve means), 70... Control device, RW……Rear wheel, R1,
R2...Main oil chamber, R3, R4...Sub oil chamber (pair of hydraulic chambers), P...Hydraulic pump (hydraulic supply device), T
...Reservoir tank.

Claims (1)

[Scope of utility model registration request] The vehicle is equipped with a hydraulic pressure supply device, a hydraulic cylinder that drives a rear wheel steering link mechanism, and a hydraulic control device that controls the amount of oil supplied from the hydraulic pressure supply device to the hydraulic cylinder to steer the left and right rear wheels. A rear wheel steering device includes a connecting member that connects the left and right rear wheels and is displaced in the axial direction as the wheels are steered, a displacement member that is provided on the connecting member and that is displaced together with the connecting member, and a displacement member that is disposed along the displacement direction of the displacement member. A pair of hydraulic chambers are defined on both sides opposite to the surface facing the displacement member by a cylinder member provided along the cylinder member and a cylinder member slidably provided on the cylinder member with the displacement member in between. A pair of piston members, a control device that determines whether rear wheel steering by the hydraulic control device is operating normally and outputs a control signal, and the operation is controlled by the control signal from the control device. When the rear wheel steering by the hydraulic control device operates normally, the hydraulic pressure supply to the pair of hydraulic chambers is cut off, and when the rear wheel steering by the hydraulic control device does not operate normally, the hydraulic pressure supply to the pair of hydraulic chambers is shut off. A steering regulation device for a rear wheel steering system, characterized in that a switching valve means is connected to a hydraulic pressure supply device and bleeds hydraulic pressure in the hydraulic cylinder.