JPH044941Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a safety device for four-wheel steering vehicles such as rough terrain cranes.

Conventional technology The front and rear wheels are mounted on the front and rear of the vehicle body so that they can swing freely using front and rear steering cylinders, so that the front and rear wheels can be steered, or only the front two wheels can be steered. A four-wheel steering vehicle is known.

Problems that the invention aims to solve: The turning radius is significantly different when steering with 4 wheels and when steering with 2 wheels, so it is difficult to control the steering angle, running speed, etc. during 4-wheel steering with the same feeling as when steering with 2 wheels. If the vehicle is steered in the opposite direction, the vehicle will make a sudden turn with a smaller turning radius than when the two wheels are steered, so a large lateral inertia force will be applied to the vehicle body during the turn, making the vehicle unstable, and in extreme cases, it may fall over, which is extremely dangerous. be.

Means and operation for solving the problem A means for detecting the unlocked state of the rear steering lock mechanism and a means for detecting the high speed shift position, and when the detection signals from both means are input, the vehicle speed is changed to 4 to the traveling speed control mechanism. The vehicle is equipped with a controller that outputs a signal to prevent the speed from exceeding a safe allowable speed during wheel steering, thereby preventing the running speed of the vehicle from exceeding a speed at which stability is maintained during four-wheel steering.

Embodiment FIG. 2 is a schematic perspective view of a running vehicle, and the vehicle body 1
Front and rear axles 2 and 3 are supported so as to be swingable left and right via front left and right suspension cylinders 4 and 5 and rear left and right suspension cylinders 6 and 7, respectively. Left and right front wheels 8F and rear wheels 8R are swingably provided on the left and right drive shafts (not shown) provided inside, and the front wheels 8F and rear wheels 8R are connected to a front steering cylinder 9 and a rear steering cylinder 10. It swings from side to side, making it a four-wheel steering vehicle.

The left and right drive wheels are connected to the front and rear propulsion shafts 11 and 12 via differentials (not shown), and
1 and 12 are connected to the output side of the transmission 13, and the input side of the transmission 13 is connected to the torque converter 1.
The rotation speed of the engine 15 is controlled by increasing or decreasing the injection amount of the fuel injection pump 16 with a control lever 17, and the control lever 17 is connected to the output side of the engine 15 via the link mechanism 1.
8 to an accelerator pedal 19.

The rear axle 3 has the rear wheel 8R in the center position,
That is, there is provided a rear steering lock mechanism 20 that swings and locks the vehicle in a straight-ahead position, such as a mechanism that fits a lock pin 21 provided on the rear wheel 8R side into a pin hole 23 of the rear axle 3 using a cylinder 22.

FIG. 3 is a steering hydraulic circuit diagram, in which the steering valve 2 can switch the pressure oil discharged from the steering pump 24 with the steering handle 25.
6 to supply to the front and rear steering cylinders 9, 10, and a steering switching valve 2.
7 is provided, and this steering switching valve 27 is
A two-wheel steering position that is supplied only to the front steering cylinder 9, a crab steering position that is supplied 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, and a crab steering position that is supplied 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. It is provided with four wheel steering positions that supply the front and rear steering cylinders 9 and 10 so as to swing in opposite directions, and is also provided with a front and rear switching valve 28 that reverses the flow of pressure oil when the vehicle moves forward or backward. There is.

FIG. 4 is a suspension hydraulic circuit diagram, in which the discharge side of the first pump _P1 is connected to the inlet port 31a of the suspension height switching valve 31 via a pipe 30, and the drain port 31b is connected to the tank 32.
The first port 31c also communicates with the front left and right suspension cylinders 4, 5, and rear left and right suspension cylinders.
It is connected to the head side chambers 4a, 5a, 6a, 7a of 6 and 7 via the first to fourth head side pipes 33, 34, 35, 36, and the second port of the suspension height switching valve 31. 31d is connected to the rod side chambers 4b, 5b, 6b, 7b of the front left and right suspension cylinders 4, 5, 6, 7 through the first to fourth rod side conduits 37, 38, 39, 40. It has been done.

A front left pilot check valve 41 is provided in the first head side and rod side conduits 33 and 37 of the front left suspension cylinder 4, and a front left pilot check valve 41 is provided in the second head side and rod side conduit 3 of the front right suspension cylinder 5.
A front right pilot check valve 42 is provided at the rear left suspension cylinder 6, a rear left pilot check valve 43 is provided at the third head side of the rear left suspension cylinder 6, and a rear left pilot check valve 43 is provided at the rod side pipes 35, 39. A rear right pilot check valve 44 is provided on the fourth head side of the cylinder 7 and on the rod side conduits 36, 40.

The discharge passage 45 of the second pump _P2 is provided with a front suspension lock valve 46 and a rear suspension lock valve 47.
The front suspension lock valve 46 has a lock position A that discharges the pilot pressure from the second pump _P2 to the drain, and a front left and right pilot check valve 41,
The rear suspension lock valve 47 has a lock position that discharges the pilot pressure from the second pump _P2 to the drain. and rear left and right pilot check valves 43,
44 to open them, and is held in the locked position A by a spring force, and is switched to the free position B when the solenoids 46a and 47a are energized.

FIG. 1 is an explanatory view of the main part, and the rear steering lock mechanism 20 is provided with a detector 50 that detects the locked state and unlocked state by fitting the pin 21 into the pin hole 23, and this detection signal is sent to the controller 5.
The signal is input to the comparison calculation circuit 52 of No. 1.

The steering switching lever 53 can be operated to a 2-wheel steering position, a crab steering position, and a 4-wheel steering position, and the solenoids 27a and 27b of the steering switching valve 27 are controlled to be energized to each position. When the four-wheel steering position is set to the four-wheel steering position, the detector 54 is activated and its detection signal is input to the comparison calculation circuit 52.

The transmission 13 is operated to change speed by a speed change lever 55, and when the speed change lever 55 reaches a high speed change position _F3 , a detector 56 is activated and a detection signal is inputted to the comparison calculation circuit 52.

When the unlock state detection signal is input from the detector 50 while the four-wheel steering signal is input from the detector 54, and the high-speed shift position signal is input from the detector 56, the comparison calculation circuit 52 operates as follows. An operation signal is input to the warning device 57 and the traveling speed control mechanism 58 to issue a warning, for example, an alarm, and to prevent the traveling speed of the vehicle from exceeding a certain speed.

Here, the high speed shift position is the lowest shift position that can exceed the safe allowable speed during four-wheel steering.

Furthermore, the running speed control mechanism 58 refers to the engine 15.
This is a means for prohibiting operation of the control lever 17 to the high speed side, or an exhaust brake, etc., which decelerates the vehicle speed so that it does not exceed the safe allowable speed when steering four wheels.

Effects of the invention: When the vehicle reaches a high-speed shift position during four-wheel steering, the traveling speed control mechanism 58 is activated to prevent the vehicle from exceeding the speed at which stability can be maintained during four-wheel steering, thereby preventing the vehicle from falling over. You can prevent this from happening.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being an explanatory view of the main parts, FIG. 2 being an overall perspective view, and FIGS. 3 and 4 being hydraulic circuit diagrams. 1 is a vehicle body, 8F is a front wheel, 8R is a rear wheel, 9 is a front steering cylinder, 10 is a rear steering cylinder, 20 is a rear steering lock mechanism, 51 is a controller, and 58 is a traveling speed control mechanism.

Claims (1)

[Scope of utility model registration request] A front wheel 8F and a rear wheel 8R are provided in the vehicle body 1 and can be freely steered by front and rear steering cylinders 9 and 10,
In a four-wheel steering vehicle equipped with a rear steering lock mechanism 20 for locking the steering of the rear wheels 8R, means for detecting an unlocked state of the rear steering lock mechanism 20, and means for detecting a high speed shift position; The four-wheeled vehicle is characterized in that it is provided with a controller 51 that outputs a signal to the travel speed control mechanism 58 to prevent the vehicle speed from exceeding a safe allowable speed during four-wheel steering when the detection signals of the respective means are input. Safety device for steered vehicles.