Hydraulic Circuit Sequence Valves Thermal Expansion
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Solution Overview
Problem
The existing counterweight attaching/detaching devices in work machines, such as hydraulic excavators and cranes, are prone to damage due to thermal expansion of hydraulic fluid, which causes the hydraulic cylinder to revert to a constrained state, applying excessive force on crucial parts like the hydraulic cylinder and link member, leading to potential damage and requiring operators to halt operations to adjust the system.
Innovation Solution
The hydraulic circuit incorporates a first and second cutoff valve with sequence valves and check valves, which allow the hydraulic fluid to be released from the bottom and rod chambers during thermal expansion, maintaining an unconstrained state and preventing excessive force on the hydraulic cylinder, ensuring continuous operation without the need for operator intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hydraulic circuit uses a sealed system to maintain hydraulic pressure, then the hydraulic pressure is stable, but thermal expansion of hydraulic fluid causes the hydraulic cylinder to extend and apply excessive force on crucial parts
Solution Approach 1:
A sequence valve is introduced as an intermediary component between the sealed hydraulic system and the external environment. The sequence valve monitors hydraulic pressure and automatically opens to release excess pressure caused by thermal expansion, acting as a mediator that protects the system from damage while maintaining normal sealed operation
Solution Approach 2:
The system dynamically changes the pressure parameter by using a sequence valve set to a specific opening pressure. When thermal expansion causes pressure to exceed the predetermined threshold, the valve opens to reduce pressure, thereby adapting the system's pressure parameter to prevent damage while maintaining operational stability
2Duration of action of stationary object
If the hydraulic cylinder is kept in unconstrained state to prevent damage, then component life is extended, but operators must manually adjust the system after thermal expansion occurs
Solution Approach 1:
The sequence valve enables the hydraulic system to automatically adjust itself when thermal expansion occurs. The valve opens and closes based on pressure conditions without operator intervention, maintaining the unconstrained state and extending component life while eliminating the need for manual adjustment and reducing operational downtime
3Reliability
If thermal expansion is completely prevented, then no damage occurs to crucial parts, but the hydraulic system requires complex temperature control mechanisms
Solution Approach 1:
Instead of preventing thermal expansion through complex temperature control, the invention extracts the harmful effect by providing a pressure release path through the sequence valve. This allows thermal expansion to occur naturally but prevents it from causing damage by releasing excess pressure, thereby preventing damage without requiring complex temperature control mechanisms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively prevents damage to the hydraulic cylinder and link member by allowing thermal expansion to occur without converting the hydraulic cylinder to a constrained state, ensuring continuous operation and improved work efficiency by automatically managing fluid flow and pressure.
Implementation Method 1
thermal expansion of the hydraulic fluid causes the hydraulic cylinder to extend
Implementation Method 2
hydraulic pressure in the rod chamber applied thereto as an internal pilot pressure
Data Source
AI summary
A first cutoff valve is disposed in a main duct ranging between a control valve and a bottom chamber of a hydraulic cylinder. A sequence valve in the first cutoff valve is disposed along such a direction as to control outflow of a hydraulic fluid from the bottom chamber and the hydraulic pressure in a rod chamber is applied to the sequence valve as an external pilot pressure. A second cutoff valve is disposed in a main duct ranging between the control valve and the rod chamber of the hydraulic cylinder. A sequence valve in the second cutoff valve, disposed along such a direction as to control outflow of the hydraulic fluid from the rod chamber, and the hydraulic pressure in the rod chamber is applied to the sequence valve as an internal pilot pressure.