Spool Valve Biasing via Supply Pressure Adaptation
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Solution Overview
Problem
Existing spool valves require multiple variations to accommodate a wide range of supply pressures, leading to increased manufacturing costs and complexity for end users, as the biasing force is typically fixed and not adaptable to varying pressures.
Innovation Solution
The spool valve generates a biasing force based on a biasing pressure that corresponds to the supply pressure, allowing a single spool valve to be used across multiple applications by adjusting the biasing pressure proportionally with the supply pressure, using methods such as varying the area upon which the biasing pressure is applied or reducing the biasing pressure through flow restrictors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed biasing force is used in spool valves, then the valve can maintain stable operation at a specific supply pressure, but multiple valve variations are required to accommodate a wide range of supply pressures, increasing manufacturing costs and complexity
Solution Approach 1:
The biasing force is made dynamic by replacing the fixed spring with a pneumatic biasing mechanism that uses supply pressure to generate the biasing force. This allows the biasing force to automatically adapt to different supply pressure levels, enabling a single valve design to operate reliably across a wide range of pressures without requiring multiple pressure-rated variations.
Solution Approach 2:
The invention changes the parameter of biasing force from fixed to variable by using supply pressure as the source. The biasing pressure is derived from supply pressure through flow restrictors that create a pressure drop, resulting in a biasing force that scales with supply pressure. This parameter change allows the valve to maintain proper force balance across different operating conditions.
2Manufacturing precision
If multiple spool valve variations are manufactured to cover different supply pressure ranges, then each valve can be optimized for its specific pressure range, but the device complexity and selection process for end users increases
Solution Approach 1:
The invention makes the spool valve universal by designing it to handle multiple supply pressure ranges using the same basic structure. The pneumatic biasing mechanism with supply-pressure-derived biasing force allows the single valve design to function optimally across low, medium, and high pressure applications, eliminating the need for multiple pressure-specific valve variations and simplifying the selection process for end users.
Solution Approach 2:
The invention segments the pressure adaptation function into separate components: flow restrictors that create pressure drops to generate biasing pressure from supply pressure. This segmentation allows the main valve body to remain universal while the biasing mechanism handles the pressure-range adaptation, reducing overall device complexity.
3Force
If the biasing pressure is directly equal to supply pressure, then the biasing force is maximized, but the spool may not achieve precise positioning control across the full range of supply pressures
Solution Approach 1:
The invention introduces flow restrictors as intermediary elements between supply pressure and biasing pressure. These restrictors create a controlled pressure drop that generates biasing pressure lower than supply pressure, allowing for finer control of the biasing force. This intermediary mechanism enables precise spool positioning by providing a biasing force that is proportional to but less than supply pressure, improving positioning accuracy across the full pressure range.
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 enables a single spool valve to function effectively across a broad range of supply pressures, reducing the need for multiple valve variations and simplifying the selection process for end users, while maintaining precise control over the spool's position and movement.
Implementation Method 1
A biasing force acting on a second end of the spool is to urge the spool in a second direction within the housing opposite the first direction. The biasing force is based on the supply pressure of the fluid.
Implementation Method 2
A variable input force acting on a first end of the spool is to urge the spool in a first direction within the housing. Both the input pressure and the biasing pressure are based on a supply pressure of the fluid.
Data Source
AI summary
Apparatus to bias spool valves using supply pressure are disclosed. An example apparatus includes a sleeve of a spool valve, and a spool within the sleeve to control a flow of fluid at a supply pressure through the spool valve as the spool is moved relative to the sleeve in response to a variable input force. A biasing force is to bias the spool opposite the variable input force. The biasing force is to be generated from a biasing pressure of the fluid within a chamber adjacent a biasing end of the spool. The biasing pressure is to be based on the fluid at the supply pressure provided directly to the chamber from a supply of the fluid independent of the flow of the fluid through the spool valve.