JPH0698940B2 - Driving safety device for four-wheel steering type traveling vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a travel safety device for a four-wheel steering traveling vehicle such as a rough terrain crane.

2. Description of the Related Art Front and rear wheels are mounted on the front and rear of a vehicle body by a front and rear steering cylinder so that the front and rear wheels can swing, and the four front and rear wheels can be steered.
A four-wheel steering type traveling vehicle is known in which only two front wheels can be steered.

Problems to be Solved by the Invention Even if the steering wheel is operated by the same angle, the turning radii R and R are largely different between two-wheel steering and four-wheel steering as shown in FIGS. 3 and 4. When steering with four wheels, if the steering wheel turning angle, traveling speed, etc. are the same as when steering with two wheels and the steering operation is the same, a sharper turning radius than with two wheels is used. As shown in FIG. 5, a large lateral centrifugal force F acts on the vehicle body a, and the suspension cylinder b on the outer side in the turning direction is deflected to lean the vehicle body a outwardly. .

Means and Actions for Solving the Problems When the steering switching valve is set to the four-wheel steering position, the suspension lock valve is set to the locking position so that the suspension can be locked during the four-wheel steering.

Example FIG. 2 is a schematic perspective view of a traveling vehicle, in which front and rear axles 2 and 3 are disposed in front of and behind the vehicle body 1 via front left and right suspension cylinders 4,5 and rear left and right suspension cylinders 6 and 7. The left and right drive shafts (not shown) installed in the front and rear axles 2 and 3 are supported by the front and rear wheels 8F and the rear wheels.
The 8R and 8R are swingable, and the front and rear wheels are 8F and
The 8R is swung left and right by the front steering cylinder 9 and the rear steering cylinder 10 to form a four-wheel steering type vehicle.

The left and right drive wheels are connected to the front and rear propulsion shafts 11 and 12 via a differential gear (not shown), and the front and rear propulsion shafts 11 and 12 are connected to the output side of the transmission 13 and the input side of the transmission 13. Is connected to the output side of the engine 15 via the torque converter 14, and the engine 15 controls the injection amount of the fuel injection pump 16 by a control lever.
The rotation speed is controlled by increasing and decreasing with 17, and the control lever 17 is connected to an accelerator pedal 19 via a ring mechanism 18.

A rear steering lock mechanism 20 for rocking and fixing the rear wheel 8R on the rear axle 3 in a center position, that is, a straight traveling posture, for example, a lock pin 21 provided on the rear wheel 8R side is fitted into a pin hole 23 of the rear axle 3 by a cylinder 22. A matching mechanism is provided.

FIG. 1 is a steering and suspension hydraulic circuit diagram in which the hydraulic fluid discharged from the steering pump 24 is supplied to the front and rear steering cylinders 9 and 10 by a steering valve 26 which can be switched by a steering handle 25, and a steering switching valve. The steering switching valve 27 is provided to the front and rear steering cylinders 9 and 10 so that the front and rear wheels 8F and 8R swing in the same direction as the two-wheel steering position I that is supplied only to the front steering cylinder 9. It has a crab steering position II and a four-wheel steering position III for supplying the front and rear wheels 8F and 8R to the front and rear steering cylinders 9 and 10 so as to swing in the opposite directions, and the vehicle moves forward and backward. A front / rear switching valve 28 that reverses the flow of pressure oil is sometimes provided.

The discharge side of the first pump P ₁ for suspension is connected to the inlet port 31a of the suspension height switching valve 31 via the line 30, and the drain port 31b communicates with the tank 32 and The port 31c is connected to the head side chambers 4a, 5a, 6a, 7a of the front left and right side and rear left and right side suspension cylinders 4,5, 6, 7 through the first to fourth head side pipelines 33, 34, 35, 36. The second port 31d of the suspension height switching valve 31 that is connected
Is the front left and right side and rear left and right side suspension cylinders 4,5,6,
In the rod side chambers 4b, 5b, 6b, 7b of 7, the first to fourth rod conduits 37, 3
It is connected through 8,39,40.

A front left pilot check valve 41 is provided on the first head side and the rod side conduits 33, 37 of the front left suspension cylinder 4, and the second head side, the rod side conduits 34, 38 of the front right suspension cylinder 5 are provided. To front right side pilot check valve 4
2 is provided, and a rear left pilot check valve 43 is provided at the third head side of the rear left suspension cylinder 6, the road side pipe lines 35, 39, and a fourth head side of the rear right suspension cylinder 7 is connected. The rear conduits 36, 40 are provided with a rear right pilot check valve 44.

The discharge passage 45 of the second pump P ₂ is provided with a front side suspension lock valve 46 and a rear side suspension lock valve 47, and the front side suspension lock valve 46 is
Lock position B for discharging the pilot pressure from the second pump P ₂ to the drain, and front left and right pilot check valves
41,42 supply these front left, right pilot check valve 4
Free position b to open 1,42 and rear suspension lock valve
47 has a lock position a for discharging the pilot pressure from the second pump P ₂ to the drain, and a free position b for supplying the pilot pressure to the rear left and right pilot check valves 43 and 44 to open them. Is held in the lock position by the solenoid 46
When a and 47a are excited, the free position is switched to b.

50 is a steering system switching switch, 51 is a suspension switching switch, the steering system switching switch 50 is provided with first and second switches 52 and 53, and the input terminal 52a of the first switch 52 is a contact piece 52b. The first, second, and third output terminals 52c, 52d, and 52e are connected, the first output terminal 52c is connected to the solenoid 27b of the steering switching valve 27, and the second output terminal 52d is connected to the solenoid 27a. The input terminal 53a of the second switch 53 is connected to the first, second and third output terminals 53c, 53d and 53e by the contact piece 53b, and the contact pieces 52b and 53b are interlocked with each other and the third output terminal 53e. Is the solenoid of the front and rear suspension lock valves 46, 47
It is connected to 46a and 47a.

The suspension switching switch 51 connects the input terminal 51a to the contact piece 51b.
Is connected to the first and second output terminals 51c and 51d with
The output terminal 51d is connected to the input terminal 53a.

Then, the contact piece 52b of the first switch 52 is connected to the first output terminal 52c.
When it is connected to the solenoid 27b, the steering switching valve 27 is switched to the four-wheel steering position III, and at the same time, the contact piece 53b of the second switch 53 is connected to the first output terminal 53c. Regardless of the switching position of 51, the solenoids 46a and 47a are demagnetized, the front and rear suspension lock valves 46 and 47 are switched to the lock position B, and each suspension cylinder is locked.

When the contact piece 52b of the first switch 52 is connected to the third output terminal 52e, the steering switching valve 27 is in the two-wheel steering position I, and the contact piece 53b of the second switch 53 is connected to the third output terminal 53e. Therefore, the contact piece 51 of the suspension lock switching valve 51
By connecting b to the second output terminal 51d, the solenoids 46a and 47a of the front and rear suspension lock valves 46 and 47 can be energized to switch to the free position b.

It should be noted that the steering switching valve 27 is not limited to the above switch, and a relay or a logic element may be used to adjust the steering switching valve 27 to the 4-wheel steering position II
When switching to I, the solenoids 46a and 47a may be de-energized to switch the front and rear suspension lock valves 46 and 47 to the locking position B, and the front and rear suspension lock valves 46 and 47 are switched to the solenoids 46a and 47a. You may make it switch to a lock position when energized.

Advantageous Effects of the Invention When the steering switching valve 27 is in the four-wheel steering position, the suspension lock valve is in the locking position and the suspension is locked, so that the vehicle body does not fall outward even if the vehicle turns while operating the four-wheel steering. Is.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 show an embodiment of the present invention, FIG. 1 is a hydraulic circuit diagram, FIG. 2 is an overall schematic perspective view, FIG. 3 and FIG.
FIG. 5 is an explanatory view of a turning operation by wheels and four-wheel steering, and FIG. 27 is a steering switching valve, and 46 and 47 are front and rear suspension lock valves.

Claims (1)

[Claims] 1. A steering switching valve 27 for switching a steering system.
And a suspension lock valve that locks the suspension, and when the steering switching valve 27 is in the four-wheel steering position, the suspension lock valve is in the locking position. Traveling safety device.