Fluid Pressure Control Device Using Pilot Valve Segmentation
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Solution Overview
Problem
Existing fluid pressure control devices are large due to the need for increased flow passage areas in pressure relief passages, which complicates the control of high and low pressure actuators while preventing pressure exceeding a certain limit from acting on low pressure actuators.
Innovation Solution
A fluid pressure control device with a branching passage, a switching valve, and a relief valve configuration that allows the working fluid to be efficiently directed to a pilot chamber, enabling pressure control without the need for extensive flow passages, thus allowing the second control valve to be downsized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flow passage area of the pressure relief passage is increased to efficiently discharge working fluid from the relief valve, then the pressure control function is improved, but the size of the second control valve and the fluid pressure control device is increased
Solution Approach 1:
A switching valve is introduced as an intermediary component between the supply passage and the relief valve. The switching valve has a pilot chamber that receives working fluid from the supply passage through the second control valve, and controls the opening/closing of the relief valve based on the pilot pressure. This intermediary mechanism allows the relief valve to be controlled without requiring a large flow passage area in the second control valve, thus resolving the contradiction between pressure control reliability and device size.
2Reliability
If the second control valve is designed to directly control both the low pressure actuator and the relief valve flow, then the pressure limit function is achieved, but the valve size increases due to the need for large flow passage area
Solution Approach 1:
The control function is segmented into two separate valves: the second control valve that controls the low pressure actuator, and the switching valve that controls the relief valve through its pilot chamber. This segmentation allows the second control valve to maintain a compact size while the switching valve handles the pressure relief control, reducing the overall structural complexity and size of the system.
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
The configuration allows for effective pressure control, preventing pressures above a certain limit from acting on low pressure actuators while reducing the overall size of the control device.
Implementation Method 1
a switching valve (50) provided in the branching passage (5) and having a pilot chamber (51) into which the working fluid is supplied from the supply passage (3) through the second control valve (26)
Data Source
AI summary
A fluid pressure control device includes a switching valve that has a pilot chamber to which the working oil is supplied from the supply passage through the second control valve, and a first relief valve that is provided on the downstream side of the switching valve. The second control valve allows supply of the working oil to the pilot chamber in a case where a flow of the working oil to a tilt cylinder is allowed, and blocks the supply of the working oil to the pilot chamber in a case where the flow of the working oil to the tilt cylinder is blocked. The switching valve allows a flow of the working oil to the first relief valve in a case where the working oil is supplied to the pilot chamber, and blocks the flow of the working oil to the first relief valve in a case where the supply of the working oil to the pilot chamber is blocked.