Integrated Pressure-Maintaining Valve for Hydraulic Purge Circuits
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Solution Overview
Problem
Existing pressure-maintaining valve designs for closed hydraulic circuits are cumbersome and require additional components, such as directional control valves or external pressure sources, to prevent pressure drops in the low-pressure working line, which can damage the variable displacement pump during periodic changes in pressure.
Innovation Solution
A pressure-maintaining valve arrangement with a valve body acted upon by a spring in the closing direction and an inlet pressure that opens the valve, utilizing a pilot valve to control the pressure chamber, allowing for efficient shut-off or normal operation without the need for additional directional control valves or external pressure sources, reducing device complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a directional control valve is provided in series with the purge valve and pressure-maintaining valve to interrupt the purge flow during change-over operations, then pressure drops in the low-pressure working line are prevented, but the device complexity increases due to the additional directional control valve
Solution Approach 1:
The patent combines the directional control function and pressure-maintaining function into a single integrated valve unit. The valve body incorporates both the directional control valve and pressure-maintaining valve functions, eliminating the need for separate directional control valves while maintaining the ability to prevent pressure drops during change-over operations.
Solution Approach 2:
The integrated valve unit performs multiple functions simultaneously: it acts as both a directional control valve for interrupting purge flow during change-over operations and as a pressure-maintaining valve for preventing pressure drops in the low-pressure working line. This multi-functionality reduces the overall number of components required.
2Reliability
If control chambers on the purge valve are relieved via pilot valves to the tank, then the purge valve passes into its central position and shuts off the purge flow, but the device complexity increases due to additional pilot valves
Solution Approach 1:
The patent integrates the pilot valve function directly into the valve body structure, combining the main valve and pilot valve functions in a single unit. This eliminates the need for separate external pilot valves while maintaining the shut-off function during change-over operations.
3Reliability
If an external pressure source is used to act upon the control chamber of the pressure-maintaining valve to shut it off, then the purge flow is shut off, but the device complexity increases due to the external pressure source requirement
Solution Approach 1:
The integrated valve unit uses its own internal pressure dynamics to control the shut-off function. The valve body incorporates pressure chambers that utilize the system's own hydraulic pressure to actuate the shut-off mechanism, eliminating the need for external pressure sources.
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 solution effectively prevents pressure drops in the low-pressure working line, reducing the risk of damage to the variable displacement pump while minimizing device outlay and maintaining efficient operation, allowing for cost-effective and stable pressure management in closed hydraulic circuits.
Implementation Method 1
A pressure-maintaining valve (9) has a valve body (24) which can be acted upon or is permanently acted upon in the closing direction by the force of a - preferably adjustable - spring
Implementation Method 2
in the opening direction by the inlet pressure tapped off upstream of the pressure-maintaining valve
Implementation Method 3
The control surface on the valve body of the pressure-maintaining valve is relieved to a tank connection of the pressure-maintaining valve, which tank connection is connectable to a tank, in a second position of the valve body of a pilot valve
Data Source
AI summary
A pressure-maintaining valve arrangement of a purge circuit of a closed hydraulic circuit includes a pressure-maintaining valve configured to be shut off via a pilot valve. In one embodiment, a control pressure chamber, acting in the closing direction, of the pressure-maintaining valve is configured to be relieved via the pilot valve to a tank, and the pressure-maintaining valve is closed via a spring acting in the closing direction. In another embodiment, the valve arrangement includes an additional control pressure chamber acting in the closing direction. The additional control pressure chamber is configured to be loaded via the pilot valve, and the pressure-maintaining valve closes. The pressure of the inlet of the pressure-maintaining valve is used for this purpose.