JPH0584272B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a four-wheel steering device that can control front and rear wheels simultaneously.

(Prior Art) In conventionally known devices of this type, a mechanical link mechanism is connected to a front wheel steering device, and the rear wheels are steered via this link mechanism.

(Problems to be Solved by the Present Invention) The conventional device as described above requires a space for arranging the link mechanism, and therefore has a problem that it cannot be easily installed in a current vehicle.

An object of the present invention is to provide a device that eliminates the need for a link mechanism and that can be easily installed on existing vehicles.

(Means for solving the problem) In order to achieve the above object, the first invention:
A spool of a control valve is connected to the ring gear of the planetary gear, and pressurized oil is selectively supplied to the actuator that exerts steering force to the front wheels through the control valve that switches based on the input rotation of the handle. first to control
In a steering system in which a second control valve is arranged in parallel in addition to the control valve, a hydraulic cylinder is provided in the shaft portion of the leaf spring on the rear wheel side to move the shaft in the traveling direction of the vehicle, and the hydraulic cylinder and the second control valve are connected to each other. The valves are connected to each other via a directional switching valve, and when this directional switching valve is switched to a position other than the neutral position, the front and rear wheels are controlled simultaneously.

Further, a second invention is the first invention, in which the steering angle of the rear wheels proportional to the steering angle of the front wheels can be obtained in accordance with the signals of the steering angle meter of the handle part and the displacement detection means of the hydraulic cylinder part. A controller has been added to control the

(Action of the present invention) With the above configuration, in the first invention,
When the handle is rotated with the directional control valve switched, the first control valve switches to drive the actuator that steers the front wheels, and the second control valve also switches to drive the hydraulic cylinder that controls the rear wheels. let

Further, in the second invention, the controller functions to control the steering angle of the rear wheels according to the steering angle of the front wheels.

(Effects of the Present Invention) According to the first invention, since the rear wheels can be controlled via hydraulic pressure, there is no need for a conventional link mechanism, and costs can be reduced accordingly.

In addition, it is sufficient to provide a first control valve and a second control valve on the ring gear of the planetary gear, connect a hydraulic cylinder to the shaft, and connect both of them with a directional control valve. Easy to connect.

According to the second invention, due to the action of the controller,
The steering angle of the rear wheels can be kept in an optimal state each time, such as by making it proportional to the steering angle of the front wheels.

(Embodiment of the present invention) In the first embodiment shown in FIGS. 1 to 6, a valve housing 2 is fitted to one side of a gear case 1, and a piston 3 is installed inside the gear case 1. .

One end of a wormshaft 4 is engaged with the piston 3, while the other end of the wormshaft 4 projects into the valve housing 2.
A flange 5 is formed on the protruding end, and a thrust needle bearing 7 using a needle roller is provided between the flange 5 and the side wall 6 of the valve housing 2.

Further, a lock nut 8 is provided on the outside of the side wall 6.
A thrust needle bearing 9 similar to the above is also installed between the lock nut 8 and the side wall 6.
has been established.

Both thrust needle bearings 7 and 9
This supports the axial force of the wormshaft 4 in the axial direction.

Further, a stub shaft 10 is fitted to a flange 5 formed at the other end of the worm shaft 4 so as to be relatively rotatable, and the stub shaft 10 and the worm shaft 4 are connected via a torsion bar 11 connected to one end of the worm shaft 4. are connected.

A plug 12 is provided in the valve housing 2, and the stub shaft 10 is supported by a ball bearing 13 formed on the plug 12.

A flange 10a is formed on the stub shaft 10, and a plurality of planetary gears 14 are provided around the flange 10a.

Furthermore, the valve housing 2 includes a ring gear 1.
5 is installed internally, and the planetary gear 14 is meshed with this ring gear 15, and this planetary gear 14 is also meshed with the sun gear 16.

The valve ring gear 15 thus constructed has a first control valve 18a and a second control valve 18b installed therein.
8a, 18b from the direction perpendicular to their axes, and this spool 1
Both ends of 9 are exposed to reaction force chambers 20 and 21.

As the input rotation of the handle is input, the stub shaft 10 rotates while twisting the torsion bar 11. With this rotation, the planetary gear 14 rotates and revolves around the sun gear 16, so that the ring gear 15 is rotated. While rotating, both control valves 18a and 18b are switched in opposite directions.

When the first control valve 18a is switched to either the left or right side as described above, the pump port 22 to which pressure oil is supplied communicates with either the chamber 1a or 1b in the gear case 1, and either the other The chamber 1b or 1a communicates with the tank port 23 to move the piston 3 in either direction.
When the piston 3 moves in this manner, the sector gear 24 rotates to switch the front wheels F to a predetermined steering direction.

Further, when the second control valve 18b is switched as described above, the port 2 on the upstream side of the directional control valve 25 connected to the lower sulfur side of the second control valve 18b
Either port 6 or 27 is communicated with pump port 28, and the other port is communicated with tank port 29.

The upstream ports 28 and 29 are connected to the second control valve 1.
The directional control valve 25 connected to the valve 8b has one downstream port 30 connected to a rod side chamber 34 of a hydraulic cylinder 32 for rear wheel steering and a bottom side chamber 36 of a hydraulic cylinder 33. Further, the other port 31 is connected to a bottom side chamber 36 of the hydraulic cylinder 32 and a rod side chamber 35 of the hydraulic cylinder 33.

The hydraulic cylinders 32, 33 have their bottom sides fixed to the frames 38, 39 of the vehicle body, and the tips of the piston rods 40, 41 are connected to the shackle portions 44 of the leaf springs 42, 43.
It is connected to 45.

Therefore, when the directional control valve 25 is held at the neutral position shown, the hydraulic cylinders 32, 33
is in a free state, so the steering mode is the same as a normal front-wheel steering vehicle.

Then, turn the handle with the directional control valve 25 switched to the lower position in the drawing, and turn the handle to the second control valve 18.
b to one port 26 of the switching valve 25.
to the pump port 28 and the other port 27
If the pressure oil is communicated with the tank port 29, the rod side chamber 34 of one hydraulic cylinder 32 is supplied with pressure oil via the ports 26 and 30.
The hydraulic cylinder 32 contracts. At the same time, also in the bottom side chamber 37 of the other hydraulic cylinder 33.
Pressure oil is supplied via the ports 26 and 30, and the cylinder 33 is expanded.

As described above, when one hydraulic cylinder 32 contracts, the leaf spring 42 expands, and when the other hydraulic cylinder 33 expands, the leaf spring 43 contracts, so that the rear wheel R is moved normally as shown in FIG. Move to the right of the position.

Furthermore, if the handle is turned in the opposite direction in the above state, one hydraulic cylinder 32 will expand and the other hydraulic cylinder 33 will contract, so that the rear wheel R is moved from the normal position as shown in FIG. Move to the left.

Even when the port 26 side is connected to the pump port 28 and the port 27 side is connected to the tank port 29 as described above, the directional control valve 25
When the rear wheel R is switched to the upper position in FIG. 2, the rear wheel R moves in the opposite direction to that shown in FIGS. 3 and 4.

Therefore, depending on the switching position of the directional control valve 25, the steering relationship between the front wheels F and the rear wheels R can be changed from the case of FIGS. The mode can be converted to the case of FIGS.

For example, when the directional switching valve 25 is switched to the lower position in FIG. 2, the rear wheel R moves in the same direction as the front wheel F, and when the directional switching valve 25 is switched to the upper position,
If the rear wheels R are set to move in the opposite direction to the front wheels F, the lower switching position of the directional control valve 25 can be set to the high speed mode, and the upper switching position can be set to the low speed mode.

In the high-speed mode, as shown in Figures 3 and 4, the rear wheel R moves in the same direction as the front wheel F.
Even if the steering direction of the front wheels F is changed when driving at high speed, the rear wheels R will not skid or the vehicle body will not roll when cornering.

Furthermore, during low-speed driving, the rear wheels R move in the opposite direction to the front wheels F, as shown in FIGS. 5 and 6, so the radius of rotation can be made extremely small, making it possible to make tight turns.

The second embodiment shown in FIG. 7 is provided with a controller 47 that is controlled on and off by a switch 46, and this controller 47 includes a steering angle meter 48 that detects the steering angle of the steering wheel, and a hydraulic cylinder. Displacement detection means 49 for detecting displacements of 32 and 33 are connected.

However, if the switch 46 is turned off,
Since the directional control valve 25 maintains the illustrated neutral position, the normal state of only front wheel steering is maintained.

When the switch 46 is turned on, the controller 47 functions to detect the difference between the steering angle of the handle and the displacement of the hydraulic cylinders 32, 33, and operates the directional control valve in a direction to eliminate the difference. Therefore, in this embodiment, the steering angle of the rear wheels R can always be kept constant according to the steering angle of the front wheels F.

[Brief explanation of the drawing]

Figures 1 to 6 show a first embodiment of the present invention. Figure 1 is a sectional view of the power steering section, and Figure 2 is an explanatory diagram of the steering section taken along the - line in Figure 1. , FIGS. 3 to 6 are explanatory diagrams showing the steering relationship between the front wheels and rear wheels, and FIG. 7 is an explanatory diagram of the second embodiment. 14... Planet gear, 15... Ring gear, 18
a...First control valve, 18b...Second control valve, 25...Directional switching valve, 32, 33...Hydraulic cylinder, 42, 43...Leaf spring, 4
4, 45...Shackle, R...Rear wheel, F...Front wheel, 47...Controller, 48...Steering angle meter,
49...Displacement detection means.

Claims (1)

[Claims] 1. A spool of a control valve is connected to a ring gear of a planetary gear, and pressure oil is selectively supplied to an actuator that exerts a steering force to the front wheels via a control valve that switches based on input rotation of a steering wheel. In a steering system in which a second control valve is provided in parallel with the first control valve that controls the actuator, a hydraulic cylinder is provided in the shackle portion of the leaf spring on the rear wheel side to move the shackle in the traveling direction of the vehicle. , the hydraulic cylinder and the second control valve are connected via a directional switching valve, and when the directional switching valve is switched to a position other than the neutral position, the front and rear wheels are controlled simultaneously. Steering device. 2 A spool of a control valve is connected to the ring gear of the planetary gear, and pressurized oil is selectively supplied to the actuator that exerts the steering force for the front wheels through the control valve that switches based on the input rotation of the handle, and the actuator In a steering system in which a second control valve is arranged in parallel in addition to a first control valve that controls and the second control valve are connected via a directional control valve, and the rear wheels are steered in proportion to the front wheel steering angle in response to signals from a steering angle meter in the handle and a displacement detection means in the hydraulic cylinder. A four-wheel steering device equipped with a controller that controls the angle.