Auxiliary coupler pressure relief hydraulic system with pump drive ignition switch relief

• US 4,881,371 A
• Filed: 07/26/1988
• Issued: 11/21/1989
• Est. Priority Date: 07/26/1988
• Status: Expired due to Term

• Current Assignee: Clark Equipment Company (Doosan Heavy Industries and Construction Company Limited)
• Original Assignee: Clark Equipment Company (Doosan Heavy Industries and Construction Company Limited)
• Inventors: Shelbourn, William C., Haeder, Thomas Q.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/224,165
• Time in Patent Office: 483 Days
• Field of Search: 60/427, 60/431, 60/433, 60/493, 60/911, 91/459, 91/464, 123/179 A, 123/179 B, 180/14.3, 180/53.4
• US Class Current: 60/431
• CPC Class Codes: B60R 16/00 Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for devices for protecting vehicle occupants in case of accidents B60R21/00; safety belts B60R22/00; central door locking E05B49/00, E05B77/50
• CPC Class Codes: Y10S 60/911 Fluid motor system incorporating electrical system

Abstract

An auxiliary coupler pressure relief hydraulic system for off-road vehicles including a battery, an engine, an engine ignition system, a reservoir of hydraulic fluid, and a pump for providing hydraulic fluid under pressure. Quick couplers couple hydraulic fluid to an attachment mounted to the vehicle. An electro-hydraulic spool valve is connected to a source of pilot pressure and controls the flow of hydraulic fluid to the quick couplers in response to valve actuating signals. Forward and reverse auxiliary control switches are coupled to the spool valve and provide valve actuating signals resulting in fluid flow to the quick couplers in forward and reverse directions. Also included is an ignition switch having RUN, OFF and RELIEF positions. When switched from its RUN position to its RELIEF position, the ignition switch provides pressure relief valve actuating signals which stroke the spool valve and bleed pressure trapped between the valve and the quick couplers while the engine RPM is decreasing and pilot pressure is still available.

Claims

1. An auxiliary coupler pressure relief hydraulic system for a mobile vehicle, including:

a battery;

an engine;

an engine ignition system;

an operator actuated ignition switch having RUN and OFF positions, for controlling the flow of electricity to the engine ignition system;

a reservoir of hydraulic fluid;

a pump coupled to the engine and reservoir for providing hydraulic fluid under pressure;

coupler means for coupling hydraulic fluid to an attachment;

an electro-hydraulically actuated control valve connected in a hydraulic circuit between the pump and the coupler means, for controlling the flow of hydraulic fluid to the coupler means in response to valve actuating signals;

operator actuated auxiliary control switch means coupled to the control valve for providing attachment control valve actuating signals; and

operator actuated pressure relief switch means coupled to the control valve and capable of providing electrical pressure relief valve actuating signals to the control valve after the ignition switch has been switched to its OFF position and while the engine RPM is decreasing to zero, thereby actuating the control valve and relieving pressure between the control valve and coupler means.

2. The hydraulic system of claim 1 wherein the ignition switch has a RELIEF position and further includes means functioning as the pressure relief switch means, wherein the ignition switch provides the pressure relief valve actuating signals when switched to its RELIEF position.

3. The hydraulic system of claim 1 wherein

the system further includes a pilot pressure source;

and

the electro-hydraulically actuated control valve is connected to the pressure relief switch means and the pilot pressure source.

4. An auxiliary coupler pressure relief hydraulic system for a mobile vehicle, including:

a battery;

an engine;

an engine ignition system;

a reservoir of hydraulic fluid;

a pump coupled to the engine and reservoir for providing hydraulic fluid under pressure;

coupler means coupling hydraulic fluid to an attachment;

a pilot pressure source;

an electro-hydraulic spool valve coupled to the pilot pressure source and connected in a hydraulic circuit between the pump and the coupler means, for controlling the flow of hydraulic fluid to the coupler means in response to valve actuating signals;

auxiliary control switch means coupled to the spool valve for providing attachment control valve actuating signals; and

an operator actuated ignition switch having RUN, OFF and RELIEF positions for controlling the flow of electricity from the battery to the engine ignition system and the spool valve, wherein the ignition switch provides pressure relief valve actuating signals to the spool valve when the ignition switch has been switched to its RELIEF position and while the engine RPM is decreasing to zero.

5. The pressure relief hydraulic system of claim 4 wherein the RELIEF position of the ignition switch is a position opposite the OFF position from the RUN position.