JPH0215013Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rear wheel steering device for a front wheel drive vehicle or the like.

Conventionally, the rear wheels can be steered as well as the front wheels,
Vehicles with reduced turning radius and improved maneuverability have been developed. Such a rear wheel steering device is configured to be able to steer the rear wheels from neutral to any position to the right or left in a plurality of steps or steplessly.

However, such rear wheel steering devices are generally hydraulically driven, requiring a complicated structure to maintain the rear wheels at a desired steering position, and are not always reliable. I couldn't say it was enough.

For example, as an example of such a rear wheel steering device,
There is a hydraulically driven actuator that steers the rear wheels, and an elastic member that applies an elastic biasing force is provided in the hydraulically driven actuator, and the actuator is returned to a neutral position by the biasing force of the elastic member. .
Then, the hydraulic pressure supplied to this actuator is controlled in accordance with the driving condition, etc., and this actuator is displaced to a position where the driving force generated by this pressure is balanced with the elastic force of the above-mentioned elastic member, and the rear wheel There is one that controls the steering angle arbitrarily.

However, with this type of rear wheel steering device, the rear wheels are held at a desired steering position by balancing elastic force and hydraulic pressure, so it is not possible to maintain that position reliably, resulting in poor maneuverability and reliability. It's not enough.

In order to solve this problem, some systems apply a large initial load to the elastic member in a neutral state, thereby increasing the position holding force at any steering position. However, even with such a device, the position is essentially maintained by a balance between the elastic force and the hydraulic pressure, so its ability to maintain the position cannot be said to be sufficient.

In addition, a hydraulic chamber that generates a driving force in the direction of returning the actuating part of the actuator to the neutral position and a hydraulic chamber that generates a driving force in the direction of moving the actuating part away from the neutral position are provided in the actuator. A differential pressure is applied between the hydraulic pressures supplied to these hydraulic chambers, and the actuator is actuated by this differential pressure. In this type of steering wheel, the actuating parts of the actuator are always pressed against each other by hydraulic pressure in opposite directions, so the ability to maintain the position at any steering position is large. However, in such a device, the structure of the actuator and the hydraulic pressure supply system is complicated, and the position is essentially maintained by a hydraulic lock, so that its position holding ability cannot be said to be sufficient.

The present invention was developed based on the above circumstances, and its purpose is to be able to hold the rear wheels in any steering position, to have a simple structure, to have a large position holding ability, and to be reliable. This provides a rear wheel steering device with high performance.

That is, in the present invention, the stopper that comes into contact with the rear wheel steering mechanism that steers the rear wheels and mechanically limits the amount of steering displacement thereof is movable. Accordingly, the limit amount of displacement of the rear wheel steering mechanism is configured to change, and a stopper driving means is provided to drive the stopper so as to displace it, and the stopper is driven in accordance with the running condition of the vehicle. A control means is provided for controlling the displacement of the stopper.

In the rear wheel steering device of the present invention, the rear wheels and the rear wheel steering mechanism are steered and driven by an actuator, the rear wheel steering mechanism is steered and displaced until it comes into contact with the stopper, and the rear wheel steering mechanism is steered and displaced until it contacts the stopper. The steering wheel is held at a steering position whose displacement is regulated by the steering wheel. The displacement of the stopper is controlled in accordance with the steering condition of the vehicle, and therefore the steering position of this rear wheel steering mechanism is also adjusted to a predetermined steering position in accordance with the vehicle's running condition. held in position. In this device, the rear wheel steering mechanism is always held in a position where it is mechanically abutted against the stopper by the driving force of the actuator, so the position holding ability is large and the structure is simple.

This stopper may be any type of stopper as long as the stopper itself changes the contact state with the rear wheel steering mechanism and changes the mechanical displacement restriction position of the rear wheel steering mechanism. However, in a preferred embodiment, the stopper is a tapered member that radially fits into the rotor that forms part of the rear wheel steering mechanism, and controls the amount of radial movement of the stopper. Accordingly, the amount of rotation of the rotor, that is, the amount of steering of the rear wheels is mechanically regulated. Additionally, in this preferred embodiment, the stopper is configured to move fully forward and fully engage the rotor, thereby also functioning as a locking body for locking the rotor, ie, the rear wheel steering mechanism, in the neutral position. ing.

An embodiment of the present invention will be described below with reference to the drawings. In the figure, 1 is an axle beam, and this axle beam 1 is supported by trailing rods 2, 2. The front end portions of the trailing rods 2, 2 are rotatably attached to the vehicle body 3. In order to steer the rear wheels of this vehicle in accordance with the amount of steering of the front wheels, a rear wheel steering mechanism as described below is provided. That is,
Rotary type steering actuators 4, 4 are attached to both ends of the axle beam 1.
King pins 5, 5 are rotatably supported on these steering actuators 4, 4. And these king pins 5, 5, Natsukuru 6,
6 are attached, and rear wheels 7, 7 are attached to these knuckles 6, 6. The above kingpin 5,
5 is rotationally driven by the above-mentioned steering actuators 4, 4, thereby steering the rear wheels 7, 7. Further, 10 and 10 are front wheels, 11 is a power steering mechanism thereof, and 12 is a steering wheel. The steering amount of the front wheels 10, 10 is configured to be detected by a steering detector 13. Further, 14 is a speed detector configured to detect the speed of the vehicle. Signals from these steering detector 13 and speed detector 14 are sent to a steering controller 15.
The steering controller 15 generates a signal based on the signals from the steering detector 13 and the speed detector 14 to lock the rear wheels 7, 7 in neutral when the speed is higher than a predetermined speed, for example. It is configured to output a signal for controlling the steering of the rear wheels 7, 7 in accordance with the amount of steering of the front wheels 10, 10 when the speed is below a predetermined speed. The signal from the steering controller 15 is then sent to the control valve mechanism 16. The control valve mechanism 16 controls the hydraulic pressure from the hydraulic pressure supply mechanism 17 based on the signal from the steering controller 15 and supplies it to the steering actuators 4, 4, thereby driving the steering of the rear wheels 7, 7. and front wheel 1
It is configured to control the steering angles of the rear wheels 7, 7 in response to steering angles of 0 and 10, as will be described later.

Next, the configuration of the steering actuators 4, 4, etc. will be explained with reference to FIG. That is, 20 is a housing of the steering actuator 4, and a rotor 21 is accommodated within this housing 20. This rotor 21 has the above-mentioned king pins 5, 5
The front wheels 7, 7 are steered by rotating the king pins 5, 5. Further, stators 22, 22 are fixed inside the housing 20, and these stators 2
The rotor 21 is rotationally driven by supplying hydraulic pressure between the rotor 21 and the rotor 21. A pair of lock recesses 23, 23 are formed on the outer peripheral surface of the rotor 21, and these lock recesses 23, 23 are formed in a tapered shape.

Further, this steering actuator is provided with a steering amount limiting means that mechanically limits the amount by which the rear wheels can be steered, as described below. That is, the housing 20 is formed with a pair of cylinder parts 24, 24. And these cylinder parts 2
4 and 24 are each provided with a stopper 2 which also serves as a locking body for locking the rotor 21 in the neutral position.
5 and 25 are slidably housed in a liquid-tight manner. These stoppers 25, 25 are provided with tapered lock protrusions 26, 26, respectively, and these stoppers 25, 25 are provided with springs 27, 26, respectively.
27 in the direction approaching the rotor 21, and when these stoppers 25, 25 are fully advanced by the urging force of these springs 27, 27, the lock convex portions 26, 26 move toward the rotor 21.
The rotor 21 is fitted into the lock recesses 23, 23 of the rotor 21, and the rear wheels 7, 7 are locked in the neutral position. Further, the housings 20 of these steering actuators 4, 4 are provided with stopper position detectors 28, 28, and the positions of the stoppers 25, 25 are configured to be detected by these stopper position detectors 28, 28. ing. These stopper position detectors 2
The signals from 8 and 28 are configured to be sent to the steering controller 15 described above.

Further, the power steering mechanism 11 is equipped with a power cylinder 30 and a pilot valve 31. Moreover, the above-mentioned hydraulic pressure supply mechanism 1
6 is composed of a hydraulic pump 41, a reserve 42, and the like. The hydraulic pressure supplied from the hydraulic pump 41 is applied to the power cylinder 30 via the pilot valve 31 of the power steering mechanism.
The front wheels 10, 10 are configured to be supplied to the steering wheel and to steer the front wheels 10, 10 left and right.

Further, the control valve mechanism 16 is provided with a steering switching valve 51.
is configured to be switched and operated by a signal from the steering controller 15. The hydraulic pressure supplied from the pilot valve 31 of the power steering mechanism 11 is transferred to the steering switching valve 5.
1 to the rotor 2 of the steering actuator 4, 4
1 and the stators 22, 22, so that when the front wheels 10, 10 are steered to the right or left, the rear wheels 7, 7 are also steered to the left or right in response. It is configured. Further, this control valve mechanism is provided with a pressure control valve 52 and on-off valves 53 and 54. The hydraulic pressure discharged from the hydraulic pump 41 of the hydraulic pressure supply mechanism 17 is applied to the lock convex portions 2 of the stoppers 25, 25 of the steering actuators 4, 4 via the pressure control valve 52 and the on-off valve 53.
It is configured to be supplied to the 6 and 26 sides.
Also, the lock protrusion 2 of the stoppers 25, 25
The 6 and 26 sides communicate with the return side of the hydraulic pressure supply mechanism 17 via the on-off valve 54 described above. and,
The steering controller 15 controls the on-off valves 53 and 54 in accordance with the steering angle of the front wheels 10 and 10, and supplies the valves to the lock protrusions 26 and 26 of the stoppers 25 and 25 of the steering actuators 4 and 4. control hydraulic pressure,
The position of the stoppers 25, 25 is controlled in accordance with the steering angle of the front wheels 10, 10. The positions of these stoppers 25, 25 are detected by stopper position detectors 28, 28, and fed back to the steering controller 15.

Next, the operation of this first embodiment will be explained. When the rear wheels 7, 7 are to be locked in neutral during high-speed driving, etc., the on-off valve 53 is closed and the on-off valve 54 is opened, and the lock convex portions 26, 26 of the stoppers 25, 25 are closed.
The side is connected to the return side to remove hydraulic pressure, and the stopper body 25,
25 is fully advanced to completely fit the lock protrusions 26, 26 into the lock recesses 23, 23 of the rotor 21, thereby locking the rotor 21 and locking the rear wheels 7, 7 in neutral.

When steering the rear wheels 7, 7, the on-off valve 54 is closed, the on-off valve 53 is opened and closed, and hydraulic pressure is supplied to the lock protrusions 26, 26 side of the stoppers 25, 25. 25 to release the neutral lock, and hydraulic pressure is supplied between the rotor 21 and the stators 22, 22 from the pilot valve 31 via the steering switching valve 51 to steer the rear wheels 7, 7 to the right or left. Drive in the direction. At the same time, the steering controller 15 controls the on-off valves 53 and 54 in accordance with the steering angle of the front wheels 10 and 10, thereby controlling the hydraulic pressure supplied to the lock protrusions 26 and 26 of the stoppers 25 and 25. do. Therefore, these stoppers 25, 25 move to a position where this oil pressure and the urging force of the springs 27, 27 are balanced. Therefore, the stopper bodies 25, 25 are connected to the front wheels 10, 10.
The depth of engagement between the lock protrusions 26, 26 and the lock recesses 23, 23 is determined in accordance with the steering angle of the front wheels 10, 10. Since these lock concave portions 23, 23, etc. have a tapered shape, the rotation angle of the rotor 21 is determined by the rotation angle between these lock convex portions 26, 26 and the lock concave portion 2.
3 and 23. Therefore, the rotor 21 driven by hydraulic pressure rotates until it comes into contact with the stoppers 25, 25 and the amount of rotation thereof is mechanically regulated, and is held in this state.
Therefore, the amount of steering displacement of the rear wheels 7, 7 is regulated to the amount of steering displacement corresponding to the amount of displacement of these stoppers 25. Therefore, these rear wheels 7, 7 are the same as the front wheels 1.
The steering angle is maintained at a predetermined steering amount corresponding to a steering angle of 0, 10, etc.

An embodiment of the present invention configured as described above can maintain the steering amount of the rear wheels at an arbitrary steering position by controlling the displacement amount of the stopper.
The structure is simple. In addition, the rear wheel steering position is maintained by the rotor of the rear wheel steering mechanism mechanically coming into contact with the stopper and being pressed by hydraulic pressure, so the ability to maintain the steering position is limited. Extremely large and reliable. In addition, in this embodiment, when this stopper moves fully forward and is completely fitted into the rotor, it also functions as a neutral lock body that holds the rotor neutrally, so it is not necessary to provide a separate neutral lock body. The structure is extremely simple.

Note that the present invention is not limited to the above embodiments. For example, the shape of this stopper is not necessarily limited to the above. Furthermore, this stopper does not necessarily have to serve as a locking body for maintaining the neutral state.

As described above, the present invention has a simple structure because the amount of steering displacement of the rear wheels can be maintained at an arbitrary steering position by controlling the amount of displacement of the stopper.
Further, this steering position is maintained by the rear wheel steering mechanism coming into contact with this stopper and being pressed by the driving force of the actuator.
Its effects are great, such as its ability to hold the steering position and its reliability.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, with FIG. 1 being a schematic diagram of the overall configuration, and FIG. 2 being a sectional view of a steering actuator. 4...Steering actuator, 6...Natsukuru,
7...Rear wheel, 11...Power steering mechanism,
15... Steering controller, 16... Control valve mechanism, 20
... Housing, 21 ... Rotor, 22 ... Stator, 25 ... Stopper, 26 ... Lock protrusion,
28...Lock body position detector.

Claims (1)

[Scope of utility model registration request] A rear wheel steering mechanism is configured to enable the rear wheels to be steered, and when the steering displacement of this rear wheel steering mechanism reaches a predetermined amount, the rear wheel steering mechanism comes into contact with the rear wheel steering mechanism and the rear wheels are steered. a stopper that mechanically limits the amount of steering displacement of the steering mechanism; a stopper driving means that drives the stopper to change the predetermined amount of contact between the rear wheel steering mechanism and the stopper; a steering actuator disposed to apply a displacement force to the wheel steering mechanism to displace the rear wheel steering mechanism and steer the rear wheels until mechanically restricted by the stopper; A rear wheel steering device comprising: control means for controlling the operation of the stopper driving means so as to change the predetermined amount accordingly.