JPH059983Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a front and rear wheel steering device that is capable of locking the steering of the rear wheels and steering only the front wheels during normal driving.

[Conventional technology]

Conventionally, such front and rear wheel steering devices include, for example,
A device having a pin insertion type rear wheel steering lock device as disclosed in Japanese Patent Application Laid-Open No. 57-175469 is known as shown in FIGS. 5 to 7.

As shown in FIGS. 5 and 6, the rear wheel hydraulic circuit 31 is connected to a rear wheel steering unit 33 that is linked to a front wheel steering 32, and connects a double acting cylinder 34 and a rear wheel steering switching valve 35. have. The double-acting cylinder 34 is connected to left and right rear wheel knuckles 36, 36 via links 37, 37 to steer the rear wheels 38, 38. The rear wheel steering switching valve 35 switches the supply of pressure oil to the working chamber of the double-acting cylinder 34.

As shown in FIGS. 6 and 7, the knuckle 36 on one side is provided with a lock lever 39 having a lock pin insertion hole 39a, and the axle 40 is provided with a bracket 41 having a lock pin fixing hole 41a.
is provided. Then, the lock pin 42, the lock pin insertion hole 39a, and the lock pin fixing hole 41
Steering stability is ensured by reducing the clearance between a and a. A hydraulic cylinder 43 having a locking pin 42 is mounted on this bracket 41. These lock levers 39, brackets 41,
A locking device 44 is constituted by a hydraulic cylinder 43 having a locking pin 42.

To operate the lock device 44 and lock the steering of the rear wheels 38, 38, the lock pin 42 is inserted into the lock pin insertion hole 39a and the lock pin fixing hole 41a to lock the pressure oil in the working chamber of the double acting cylinder 34. Do it like this.

The locking device 44 is deactivated and the rear wheels 38, 3 are locked.
8, the lock pin 42 must be removed.

[Problem that the invention attempts to solve]

However, with conventional front and rear wheel steering devices,
Lock pin insertion hole 39a and lock pin fixing hole 4
In some cases, it was difficult to insert and remove the lock pin 42 from the lock pin 1a.

This is because when the lock pin 42 is inserted or removed, the rod of the double-acting cylinder 34 cannot move freely, so the lock lever 39 is also fixed and does not move even when subjected to external force. It is.

[Purpose of invention]

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a front and rear wheel steering device in which the locking device can be easily activated and deactivated.

[Means for solving problems]

In order to achieve the above object, the present invention provides a double-acting cylinder that is connected to a rear wheel steering unit that is linked to front wheel steering, and that is connected to left and right rear wheel knuckles via links to steer the rear wheels;
It has a rear wheel hydraulic circuit equipped with a rear wheel steering switching valve that switches the supply of pressure oil to a double-acting cylinder, and locks the rear wheel steering by placing the rear wheel steering switching valve in a neutral state. In a front and rear wheel steering system having a lock device for releasing the lock, a bypass passage having a lock switching valve is provided in the rear wheel hydraulic circuit.

[Effect of invention]

When attempting to lock or release the rear wheel,
When the lock switching valve is opened, the bypass passage is connected to the rear wheel hydraulic circuit. Therefore, when the locking device is actuated and released, even if a force is applied to prevent it, the pressure oil in one working chamber of the double-acting cylinder will flow through the bypass passage to the other working chamber. The rod of the double-acting cylinder will now move freely.

[Example of idea]

Hereinafter, a front and rear wheel steering device according to an embodiment of the present invention will be explained in detail with reference to FIGS. 1 to 4.

As shown in FIGS. 1 and 2, a rear wheel hydraulic circuit 1 is connected to a rear wheel steering unit 3 that is linked to a front wheel steering 2, and is connected to a double acting cylinder 4.
, a rear wheel steering switching valve 5 , and a bypass passage 6 provided between these. The double-acting cylinder 4 has a link 8,
8 and is adapted to steer rear wheels 9', 9'. The rear wheel steering switching valve 5 switches the supply of pressure oil to the working chamber of the double-acting cylinder 4. The bypass passage 6 has a lock switching valve 6a.

As shown in FIGS. 2 and 3, the rear wheel knuckle 7 on one side is provided with a lock lever 9 having a lock pin insertion hole 9a, and the axle 10 is provided with a bracket 11 having a lock pin fixing hole 11a. It is provided. A hydraulic cylinder 13 having a lock pin 12 is provided on this bracket 11, and this hydraulic cylinder 13 is controlled by a lock switching solenoid valve 14. These lock levers 9, brackets 11, lock pins 12
A locking device 15 is activated by a hydraulic cylinder 13 having a
is configured.

A control unit 16 is provided at a suitable location on the vehicle, and its input side includes a lock switch 17 for commanding the insertion/extraction of the lock pin 12;
It is connected to a neutral switch 18 for confirming the neutral position of the lock lever 9, and lock lever switches 19 and 20 for confirming insertion/extraction of the lock pin 12. The output side of the control unit 16 is SOL1, SOL of the lock switching solenoid valve 14.
2, and SOL3 and SOL4 of the rear wheel steering switching valve 5.
, SOL5 of the lock switching valve 6a, the lock clamp 21, and the lock release lamp 22.

When trying to lock the steering of the rear wheel 9',
It is necessary to operate the lock device 15 and bring the rear wheel steering switching valve 5 into the neutral state.

The operation and effect will be explained based on FIGS. 3 and 4. First, it is confirmed by the neutral switch 18 that the lock lever 9 is in the neutral position (step S1). Next, a lock command from the lock switch 17 is manually input to the control unit 16 according to the driver's intention (step S2).
SOL2 of the lock switching solenoid valve 14 is excited by the command from the control unit 16 (step S3), and the lock pin 12 is activated by the hydraulic cylinder 13.
begins to move downward. At the same time, SOL5 of the lock switching valve 6a is excited (step S3), the lock switching valve 6a is opened, and the bypass passage 6 is connected to the rear wheel hydraulic circuit 1. Therefore, the rod of the double-acting cylinder 4 can move freely against external force, and the double-acting cylinder 4 and the nut 7
The lock lever 9 connected through the lock lever 9 follows the movement of the lock pin 12, and the lock pin 12 can be easily inserted into the lock pin insertion hole 9a and the lock pin fixing hole 11a.

The insertion of the lock pin 12 is confirmed by the lock lever switch 19, and when the lock lever switch 19 turns OFF (step S4), the lock switching solenoid valve 14 is turned off.
SOL2 and SOL5 of the lock switching valve 6a are demagnetized (step S5), and the lock lamp 21 is turned on (step S6). Therefore, the supply of pressure oil to the hydraulic cylinder 13 is stopped, and the inserted state of the lock pin 12 is maintained. At the same time, the rear wheel steering switching valve 5 is maintained in a neutral state. In this way, the vehicle can be operated with the rear wheels 9' locked.

Next, when trying to unlock the rear wheels 9', it is necessary to unlock the locking device 15 and put the rear wheel steering switching valve 5 in the neutral state. Then, a lock release command from the lock switch 17 is manually input to the control unit 16 (step S2).
SOL1 of the lock switching solenoid valve 14 is excited by the command from the control unit 16 (step S7), and the lock pin 12 is activated by the hydraulic cylinder 13.
begins to move upward. At the same time, SOL5 of the lock switching valve 6a is excited, and the lock switching valve 6a is energized.
a is opened, and the bypass passage 6 is connected to the rear wheel hydraulic circuit 1. Therefore, similarly to when the lock pin 12 is inserted, the lock lever 9 follows the movement of the lock pin 12 and is easily pulled out from the lock pin insertion hole 9a and the lock pin fixing hole 11a.

Confirmation that the lock pin 12 has been removed is performed by the lock lever switch 20, and when the lock lever switch 20 is turned OFF (step S8), the lock switching solenoid valve 14 is turned off.
SOL1 and SOL5 of the lock switching valve 6a are demagnetized (step S9), and the lock release lamp 22 is turned on (step S10). Therefore, the supply of pressure oil to the hydraulic cylinder 13 is stopped, and the lock pin 1
2 is maintained. At the same time, the rear wheel steering switching valve 5 is maintained in a neutral state. In this way, the steering lock of the rear wheels 9 is released. If you operate the front wheel steering in this state, you can steer the front and rear wheels.

According to this embodiment having the above configuration, when the rear wheel 9' is to be locked or released, when SOL5 of the lock switching valve 6a is energized, the bypass passage 6 is opened and the rear wheel hydraulic circuit is 1 and bypass. On the other hand, a force that prevents locking when the lock pin 12 is inserted into or removed from the lock device 15 (for example, when the lock pin 12 is inserted into the lock pin insertion hole 9
Even if the pressure oil in one working chamber of the double-acting cylinder 4 flows through the bypass passage 6 to the other working chamber due to this force. That is,
This force is absorbed by the double-acting cylinder 4. As a result, when the lock pin 12 is inserted or removed, the lock lever 9, which is connected to the double-acting cylinder 4 via the knuckle 7, follows the movement of the lock pin 12, making it easy to activate and deactivate the lock device 15. .

In this embodiment, the lock device 15 is of a lock pin insertion type, but it can also be applied to other mechanisms.

Further, in this embodiment, the lock pin 12 is inserted and removed by commands from the control unit 16, but it can also be done manually.

Further, the lock switching valve 6a is also controlled by a command from the control unit 16, but it can also be controlled manually.

[Effect of idea]

As described above, according to the present invention, in a front and rear wheel steering system, the locking device can be easily activated and deactivated.

[Brief explanation of the drawing]

FIG. 1 is a plan configuration diagram of a front and rear wheel steering device according to an embodiment of the present invention, FIG. 2 is a front view of a locking device of the front and rear wheel steering device, and FIG. 3 is a control command diagram of the front and rear wheel steering device. Figure 4 is a flowchart of the front and rear wheel steering system, Figure 5 is a plan configuration diagram of the conventional front and rear wheel steering system, Figure 6 is a front view of the locking device of the front and rear wheel steering system, and Figure 7 is a front view of the locking device of the front and rear wheel steering system. It is a control command diagram of the front and rear wheel steering device. DESCRIPTION OF SYMBOLS 1... Rear wheel hydraulic circuit, 2... Front wheel steering, 3... Rear wheel steering unit, 4... Double acting cylinder, 5... Rear wheel steering switching valve, 6...
...Bypass passage, 6a...Lock switching valve, 7
...Knuckle for rear wheel, 8...Link, 9'...Rear wheel, 15...Lock device.

Claims (1)

[Scope of utility model registration request] After switching the supply of pressure oil to the double-acting cylinder, which is connected to the rear-wheel steering unit that is linked to the front-wheel steering and connected to the left and right rear wheel knuckles via a link to steer the rear wheels, and the double-acting cylinder. The front and rear wheel steering device has a rear wheel hydraulic circuit equipped with a wheel steering switching valve, and has a locking device for locking and unlocking the rear wheel steering by placing the rear wheel steering switching valve in a neutral state. A front and rear wheel steering device characterized in that the rear wheel hydraulic circuit is provided with a bypass passage having a lock switching valve.