Directional Valve Pressure Limiting With Integrated Limiter Piston
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Solution Overview
Problem
Existing directional control valves in hydraulic systems lack a simple and space-efficient method to integrate pressure-limiting functions, particularly for ensuring that hydraulic consumers are subjected to fluid pressure only up to a predetermined level, especially during rapid switching changes.
Innovation Solution
The valve design incorporates a movable limiter piston within the piston chamber, which releases an additional fluid path to a tank connection when input pressure exceeds a predetermined threshold, using a preloaded piston and adjustable spring element to manage pressure levels, ensuring that the output pressure follows a degressive characteristic curve and limits excess pressure components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate pressure limiting valve is integrated into the hydraulic system, then pressure limitation function is achieved, but device complexity and space requirements increase
Solution Approach 1:
The pressure limiting function is merged with the directional control valve by integrating a limiter piston into the existing piston chamber. The limiter piston works together with the control piston to provide both directional control and pressure limitation functions within a single valve body, eliminating the need for a separate pressure limiting valve and reducing overall system complexity.
Solution Approach 2:
The directional control valve is designed to perform multiple functions: directional control through the control piston and pressure limitation through the limiter piston. This multi-functional design allows a single valve component to replace what would traditionally require multiple separate components, reducing device complexity while maintaining reliable pressure limitation.
2Reliability
If a separate pressure limiting valve is used, then pressure limitation is achieved, but the valve occupies more space in the hydraulic system
Solution Approach 1:
By combining the pressure limiting function with the directional control valve through the limiter piston mechanism, the overall volume required for pressure protection is reduced. The limiter piston shares the piston chamber with the control piston, eliminating the need for additional valve housing and reducing the total space occupied in the hydraulic system.
3Stress or pressure
If the limiter piston is positioned away from the stop, then excess pressure is discharged, but fluid flow path length increases
Solution Approach 1:
The piston chamber is segmented into different zones: a first region for the control piston and a second region for the limiter piston. This segmentation allows the limiter piston to be positioned in the second region away from the stop, providing sufficient space for pressure discharge functionality while maintaining efficient fluid flow paths through the segmented chamber design.
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 design effectively limits pressure in hydraulic systems, ensuring that hydraulic consumers are protected from excessive pressure, while maintaining efficient fluid flow and control states, thus enhancing the reliability and efficiency of directional control in hydraulic systems.
Implementation Method 1
a spring element (45) acting on the limiter piston (33) with a preloading force
Implementation Method 2
an actuating device, typically designed as an electromagnet
Implementation Method 3
a reset device, such as a return spring
Data Source
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AI summary
A valve (1) comprising: a valve housing (3) with a plurality of fluid connections (A, P, T), which include at least one supply connection (P) and at least one service connection (A), a control piston (11) which can be moved in the valve housing (3) for controlling the fluid connections (A, P, T) and an actuating device (13) that assumes different control states for the control piston (11), is characterized in that at least in one control state of the actuating device (13) the output pressure ( p_actuator) in the useful connection (A) follows the changing input pressure (p_input) in the supply connection (P) to a predeterminable pressure level (p, p').