Proportional Pressure Valve Pilot Relief for Piston Jam Release
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Solution Overview
Problem
Proportional pressure control valves in large construction machines face issues with piston jamming due to high friction and insufficient spring force, leading to safety-critical situations where the valve cannot be switched back or stopped, especially under conditions of undersupply and contamination.
Innovation Solution
A control device, designed as a measuring pin, is introduced between the valve piston and the actuating device, allowing the valve piston to be depressurized towards the tank connection, creating a pilot oil flow that generates a strong pressure drop and frees the piston from its jammed position by establishing a connection from the user port to the tank or return port.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large piston is used in proportional pressure control valves for large construction machinery, then the flow rate increases and switching times are shortened, but the friction forces increase causing piston jamming under contamination and undersupply conditions
Solution Approach 1:
A control device is introduced as an intermediary element between the valve piston and the actuating device. This control device includes a control element that can be shifted between positions to either connect or disconnect the actuating device from the tank connection, thereby mediating the force transmission and preventing direct friction-induced jamming of the main valve piston while maintaining high flow rate capability
Solution Approach 2:
The patent replaces part of the direct mechanical force transmission system with a control mechanism that uses pressure differential and controlled disconnection. Instead of relying solely on spring force to overcome friction in a direct mechanical system, the invention introduces a controlled mechanical substitution where the control element can disconnect the spring force transmission path from the jammed valve piston, allowing the piston to be freed without requiring continuous high spring force
2Reliability
If the spring force is increased to overcome friction and prevent piston jamming, then switch-back reliability improves, but the actuating force required increases and the valve cannot operate under undersupply conditions
Solution Approach 1:
The patent applies dynamics by making the spring force transmission path controllable rather than static. The control element can dynamically switch between connecting and disconnecting the spring force from the valve piston. This allows the spring force to be applied only when needed for normal operation, while during jamming conditions the control element disconnects the spring force path, preventing the need for continuously high actuating force
Solution Approach 2:
The invention changes the parameter of spring force transmission from a constant state to a variable state. By using the control element to shift between positions, the spring force applied to the valve piston can be changed from full force to zero force depending on operational conditions. This parameter change allows the system to overcome jamming without requiring continuously high actuating force
3Reliability
If a control device is introduced to prevent piston jamming, then switch-back reliability improves, but the device complexity increases
Solution Approach 1:
The control element serves multiple functions: it acts as a sealing element, a force transmission element, and a switching element. By making this single component multi-functional, the patent reduces the need for additional separate parts that would increase complexity. The control element universally handles sealing, force application, and circuit switching tasks within the valve structure
Solution Approach 2:
The patent merges the control function with the existing valve piston and actuating device structure. The control element is integrated into the existing mechanical assembly, combining the prevention of piston jamming with the existing force transmission and sealing mechanisms. This merging approach avoids adding entirely separate control systems that would increase device complexity
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 enhances switch-back reliability and prevents 'valve jamming' by generating a strong force to release the piston from its jammed state, ensuring fail-safe operation and preventing uncontrolled movements of hydraulic consumers.
Implementation Method 1
a compression spring (14), which is arranged between the main piston (12) and the pilot piston (22)
Implementation Method 2
an actuating device, in particular in the form of an energizable actuating magnet (28)
Implementation Method 3
EP 1 226 478 B1 discloses a valve, in particular a pressure regulating valve, with a valve housing, with at least one pump, service and tank connection, wherein a valve piston that can be actuated by a magnetic armature is guided in the valve housing, wherein the valve is provided with a hydraulic damping device which has a damping chamber which is fluid-carrying to the service connection via a throttle with a throttling point
Implementation Method 4
a force can be determined on the pressure-effective area that defines the throttling point. This force is directed against the deflecting force of the valve piston and thus exerts a damping effect on the entire valve piston
Data Source
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AI summary
The invention relates to a valve device, in particular in the form of a proportional pressure regulating valve, comprising a valve piston (12) which is guided in a longitudinally movable manner in a valve housing (10) and which connects a utility connection (A) to a pressure supply connection (P) and to a tank or return flow connection (T) dependent on the displacement position of the valve piston, and can be actuated by means of an actuating device (48), in particular in the form of an actuation magnet (28) that can be supplied with current. The valve device is characterized in that a control device (50) is provided between the valve piston (12) and the actuating device (48), said control device allowing the valve piston (12) to become pressureless on the valve piston side (52) facing the actuating device (48) in the direction of the tank or return flow connection (T) such that the valve piston (12) is displaced in the direction of the actuating device (48) under the supply and/or utility connection pressure, which can be actuated during operation, when the actuating device is not actuated.