Hydraulic Valve Spool Control to Reduce Switching Shock
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Solution Overview
Problem
Existing hydraulic systems for working machines, such as skid steer loaders and backhoes, face challenges in efficiently controlling the flow rate of operation fluid to hydraulic actuators, leading to potential shock and inefficiencies during valve switching.
Innovation Solution
A hydraulic system comprising a first and second constant displacement pump, fluid tubes, and control valves with a spool mechanism, where the spool movement speed is controlled by a control device to manage flow rates and reduce shock during valve switching, with a high flow valve and switching valve configuration to optimize fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the spool moves quickly from the first supply position to the first stop position, then the response time is improved, but shock occurs during valve switching
Solution Approach 1:
The control device determines in advance whether the second control valve is in the second supply position before allowing rapid spool movement. When the second control valve is in the second stop position, the spool is permitted to move quickly from the first supply position to the first stop position. When the second control valve is in the second supply position, the spool movement is restricted to prevent shock, thus preparing the system state beforehand to avoid harmful effects.
Solution Approach 2:
The spool movement speed is dynamically adjusted based on the state of the second control valve. The control device changes the movement characteristics of the spool according to real-time system conditions, allowing fast movement when safe and restricting movement when shock would occur, making the system adaptable to different operational states.
2Productivity
If the flow rate of operation fluid is increased, then the productivity is improved, but shock occurs during valve switching
Solution Approach 1:
The control device checks the state of the second control valve in advance before permitting high-speed spool movement that would cause sudden flow rate changes. By determining the system state beforehand, the control device prevents conditions that would lead to shock while maintaining the capability for high productivity when appropriate.
Solution Approach 2:
The control device continuously monitors the state of the second control valve and uses this feedback information to regulate spool movement. Based on the feedback from the second control valve's position, the control device adjusts the spool movement speed to prevent shock while maximizing flow rate when conditions permit.
Data Source
AI summary
A hydraulic system includes a control device to reduce a first movement speed to be lower than a second movement speed, the first movement speed being a speed at which a spool of a first control valve moves from a first supply position to a first stop position under a state where a second control valve is in the second supply position, the second movement speed being a speed at which the spool moves from the first supply position to the first stop position under a state where the second control valve is in the second stop position. The first supply position allows operation fluid to be supplied to a hydraulic actuator. The first stop position prevents the operation fluid from being supplied to the hydraulic actuator. The second stop position prevents the operation fluid from being supplied to a first fluid tube coupling a hydraulic pump to the hydraulic actuator.