JP2579187Y2 - Steering device for traveling work vehicle - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering device for a traveling work vehicle.

[0002]

2. Description of the Related Art FIG. 1 shows a known steering apparatus for a traveling work vehicle having a working machine cylinder for operating a vessel serving as a working machine such as a large dump truck. That is, the delivery pressure oil of the hydraulic pump 2 driven by the engine 1 is supplied and controlled by the demand valve 3 to the steering valve 4 and the work equipment valve 5, and the steering valve 4 supplies the pressure oil to the steering cylinder 6 for steering. The work machine valve 5 supplies pressure oil to the work machine cylinder 7, and the discharge pressure oil of the emergency steering hydraulic pump 9 driven by the motor 8 is supplied to the inlet side of the demand valve 5, and the hydraulic pump 2 malfunctions. At times, the steering can be performed using the discharge pressure oil of the hydraulic pump 9 for emergency steering.

[0003]

In such a steering device, the relief valve 11 is provided in the steering outlet side circuit 10 of the demand valve 3, and if the relief valve 11 is kept in the open state due to foreign matter in the circuit. Also, the discharge pressure oil of the emergency steering hydraulic pump 9 flows out from the relief valve 11 to the drain, which is dangerous because the steering operation cannot be performed.

Accordingly, an object of the present invention is to provide a steering apparatus for a traveling work vehicle which can solve the above-mentioned problem.

Means for Solving the Problems A discharge pressure oil of a hydraulic pump 2 driven by an engine 1 is supplied to a steering outlet side circuit 1.
0, a demand valve 3 for controlling supply to the working machine outlet side circuit 14 , a steering valve 4 for supplying pressure oil supplied to the steering outlet side circuit 10 to the steering cylinder 6, and supplying to the working machine outlet side circuit 14 Work machine valve 5 for supplying the pressurized oil to work machine cylinder 7 and emergency steering hydraulic pump 9 driven by motor 8
A check valve 15 provided in the steering outlet side circuit 10, a relief valve 11 provided closer to the demand valve 3 than the check valve 15 in the steering outlet side circuit 10, and the emergency steering hydraulic pump 9 A switching valve 13 for communicating and shutting off the discharge passage 12 of the hydraulic pump 9 for emergency steering.
Discharge passage 12 steering apparatus of the traveling working vehicle, characterized in that connected to the steering Li Ngubarubu 4 nearer check valve 15 in the steering outlet side circuit 10 of.

[Operation] Since the discharge pressure oil of the emergency steering hydraulic pump 9 is prevented from flowing to the relief valve 11 by the check valve 15, even if the relief valve 11 is kept in the open state, the emergency steering hydraulic pump 9 is maintained. The discharge pressure oil can be supplied from the steering valve 4 to the steering cylinder 6 to perform steering, which is safe. Switching valve 1
By connecting the discharge passage 12 to the working machine outlet side circuit 14 at 3, the discharge pressure oil of the hydraulic pump 9 for emergency steering is passed through the working machine outlet side circuit 14 and the working machine valve 5 to the working machine cylinder.
Can be supplied to the die 7.

[0005]

[Embodiment] As shown in FIG. 2, the discharge path 12 of the hydraulic pump 9 for emergency steering is connected to the steering outlet circuit 10 of the demand valve 3 and the switching valve 13 is connected to the working machine outlet circuit of the demand valve 3. 14 and shut off. Reference numeral 15 denotes a check valve, and reference numeral 16 denotes an auxiliary relief valve. The switching valve 13 is held at a shut-off position A by a spring 17 and becomes an electromagnetic switching valve that switches to a communication position B when energized to a solenoid 18. Raised position D, lowered position E, floating position F
Current is supplied at the time.

Next, the operation will be described. Since the discharge pressure oil of the emergency steering hydraulic pump 9 is supplied to the steering valve 4 side from the check valve 15 in the steering outlet side circuit 10 of the demand valve 3, the discharge pressure oil does not drain from the relief valve 11. , Relief valve 11
Can be supplied from the steering valve 4 to the steering cylinder 6 to perform steering operation. Further, when the work machine valve 5 is operated to supply pressure oil to the work machine cylinder 7, the switching valve 13 is in the communication position B, and the discharge pressure oil of the emergency steering hydraulic pump 9 is supplied to the work machine outlet side circuit of the demand valve 3. Therefore, even when the engine 1 is stopped and the hydraulic pump 2 has no discharge amount, the hydraulic oil can be supplied to the working machine cylinder 7 to operate the working machine.

[0007]

Since the check oil 15 prevents the discharge pressure oil of the hydraulic pump 9 for emergency steering from flowing to the relief valve 11, the hydraulic pump for emergency steering is maintained even if the relief valve 11 is kept open. The discharge pressure oil 9 can be supplied to the steering cylinder 6 from the steering valve 4 to the steering cylinder 6, and the steering is safe. The switching valve 13 communicates the discharge path 12 with the working machine outlet side circuit 14, so that the discharge pressure oil of the emergency steering hydraulic pump 9 is passed through the working machine outlet side circuit 14 and the working machine valve 5 to the working machine
To the solder 7.

[Brief description of the drawings]

FIG. 1 is a conventional steering circuit diagram.

FIG. 2 is a steering circuit diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 engine, 2 hydraulic pumps, 3 demand valves,
4 steering valve, 5 work machine valve, 6 steering cylinder, 7 work machine cylinder, 9 emergency steering hydraulic pump, 10 steering outlet side circuit,
11 relief valve, 12 discharge path, 14 work machine outlet side circuit, 15 check valve.

Claims (1)

(57) [Scope of request for utility model registration] 1. A demand valve 3 for controlling the supply of hydraulic oil discharged from a hydraulic pump 2 driven by an engine 1 to a steering outlet circuit 10 and a work implement outlet circuit 14, and to the steering outlet circuit 10. Steering valve 4 for supplying the pressurized oil to the steering cylinder 6 , a work implement valve 5 for supplying the pressurized oil supplied to the work implement exit side circuit 14 to the work implement cylinder 7, and emergency steering driven by the motor 8. A hydraulic pump 9, a check valve 15 provided in the steering outlet circuit 10, a relief valve 11 provided closer to the demand valve 3 than the check valve 15 in the steering outlet circuit 10, A switching valve 13 for communicating and shutting off a discharge path 12 of the hydraulic pump 9 for use with the work machine outlet side circuit 14. Steering system of the traveling working vehicle, characterized in that connecting the discharge passage 12 of the grayed hydraulic pump 9 to the check valve 15 Yorimosu <br/> tare Li Ngubarubu 4 near the steering outlet side circuit 10.