Boom Cylinder Hydraulic Circuit for Independent Recycle and Discharge Control
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Solution Overview
Problem
Conventional hydraulic control circuits for construction machines, such as hydraulic excavators, face challenges in accurately controlling flow rates and efficiency due to the configuration of spool valves, which complicates operation and increases costs, especially when handling multiple hydraulic actuators like the boom cylinder.
Innovation Solution
The proposed hydraulic control circuit uses first and second boom spool valves to independently control recycle and discharge flow rates for the boom cylinder, eliminating the need for pressure oil supply from hydraulic pumps during contraction, allowing for precise control of supply and discharge flow rates based on the operation mode of the boom cylinder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional spool valve is used to control supply flow rate, discharge flow rate, and recycled flow rate simultaneously, then the circuit structure is simple, but the relationship among supply flow rate, discharge flow rate, and recycled flow rate cannot be changed according to work content, impeding efficiency improvement
Solution Approach 1:
The invention divides the control of supply flow rate, discharge flow rate, and recycled flow rate into separate valves. Specifically, a supply flow control valve controls the supply flow rate from the hydraulic pump, a direction change-over valve controls the discharge flow rate from the hydraulic actuator, and a recycled flow control valve controls the recycled flow rate. This segmentation allows each flow rate to be independently adjusted according to work content, improving adaptability while maintaining reasonable system complexity.
2Adaptability or versatility
If a control valve is installed to control pressure oil supply amount to spool valves, then flow rate adaptability to work content is improved, but the control becomes complicated and it is hard to control the flow rate accurately
Solution Approach 1:
The invention extracts the flow control function from the spool valve and places it in dedicated control valves positioned upstream. The supply flow control valve is installed in the oil passage between the hydraulic pump and the direction change-over valve, and the recycled flow control valve is installed in the oil passage between the hydraulic actuator and the direction change-over valve. This extraction simplifies the control logic by separating flow rate control from direction control, making the system easier to operate while maintaining high adaptability.
3Productivity
If the spool valve controls all flow rates simultaneously, then the valve structure is simple, but the opening areas for oil supply, oil discharge, and oil recycle are uniquely determined by spool valve position, reducing operational efficiency
Solution Approach 1:
The invention segments the flow control functions into three separate valves: supply flow control valve, direction change-over valve, and recycled flow control valve. Each valve controls a specific flow rate independently, allowing the opening areas to be uniquely determined by individual valve positions rather than a single spool valve position. This enables optimized flow rate relationships for different work contents, significantly improving operational efficiency.
Data Source
AI summary
To make it possible to control supply, discharge, and recycled flow rates independently of each other for the boom cylinder in a construction machine comprising first and second boom spool valves respectively connected to first and second hydraulic pumps. When the boom cylinder is contracted, the first boom spool valve is configured to control the recycled flow rate from head side oil chamber to rod side oil chamber, the second boom spool valve is configured to control the discharge flow rate from head side oil chamber to oil tank, and both first and second boom spool valves are configured not to supply pressure oil from first and second hydraulic pumps to the boom cylinder.