Valve Arrangement Fail-Safe Pressure Control
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Solution Overview
Problem
Conventional fluid systems with directional valves suffer from energy losses and safety issues due to pressure drops and potential incorrect sensor readings, leading to unpredictable load movements in applications like crane arms, which can result in sudden drops of loads.
Innovation Solution
A valve arrangement with separate pilot valves and a pressure-controlled valve cone mechanism that ensures a fail-safe operation by only connecting the input and output ports when the input pressure exceeds the output pressure, preventing accidental opening and energy recovery through reversible pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional directional valve is used to control fluid flow, then the system is simple in structure, but energy losses occur due to pressure drops and fluid drainage to tank
Solution Approach 1:
The single directional valve is segmented into four separate 2-port valves (21a-21d), each controlling a specific fluid path. This segmentation allows independent control of supply and drain functions, enabling energy recovery by routing fluid back to the pump instead of always draining to tank, thus reducing energy losses while maintaining manageable structural complexity through modular valve design
2Loss of energy
If separate controllable valves are used to minimize energy losses, then energy efficiency improves, but the system becomes more complex and requires multiple sensors and CPU control
Solution Approach 1:
The valve arrangement incorporates a fail-safe mechanism that automatically prevents sudden load drops without requiring external monitoring or control intervention. The inherent mechanical design ensures that if pressure sensors fail or provide incorrect readings, the valve physically prevents opening under unsafe conditions, making the system self-protecting and reducing reliance on complex electronic control and redundant sensors
3Loss of energy
If pressure sensors are used to optimize control strategy, then energy efficiency improves, but safety risks increase due to potential incorrect sensor readings causing sudden load drops
Solution Approach 1:
The valve arrangement incorporates a fail-safe mechanism that proactively prevents the harmful effect of sudden load drops before they can occur. By designing the valve to physically require a minimum pressure differential to open, the system preemptively blocks the failure mode that would result from incorrect sensor readings, making safety independent of sensor accuracy
4Loss of energy
If the valve allows flow control in both directions for energy recovery, then energy efficiency improves, but the risk of inadvertent opening and sudden load drops increases
Solution Approach 1:
The valve design changes the critical parameter for opening from electrical control signals alone to a physical pressure differential threshold. The valve cone geometry and spring preload are designed to require a minimum pressure difference between inlet and outlet ports before the valve can open, regardless of electrical actuation signals. This parameter change ensures bidirectional flow control capability while preventing inadvertent opening, as the mechanical pressure threshold provides inherent safety against sudden load drops
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 provides a reliable and energy-efficient fail-safe mechanism that prevents sudden load drops by ensuring the valve only opens when input pressure exceeds output pressure, allowing for controlled and safe fluid flow in both directions, thereby minimizing energy losses and ensuring system safety.
Implementation Method 1
a valve cone (46) actuable by a fluid pressure differential between the inlet valve port (42) and the outlet valve port (43)
Implementation Method 2
a resilient spring (48) arranged to act on the valve cone (46)
Data Source
AI summary
A valve arrangement is provided for selectively connecting a source of fluid pressure to a consumer in order to actuate the consumer in a predetermined direction. The valve arrangement utilizes a valve cone arranged in the valve body which connects the valve ports with each other when the valve cone is in its open position, and is actuated by a holding force which is greater than the force acting on the pressurized fluid side of the valve cone and dependent on the medium pressure in the input port.