Capacity Control Valve With Dual Pressure Paths for Stable Startup
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Solution Overview
Problem
Existing capacity control valves for variable displacement compressors face challenges in rapid startup responsiveness and operational efficiency due to the slow exhaustion of liquefied fluid from the control chamber and differential pressure imbalances leading to wobbling strokes and reduced maximum displacement state.
Innovation Solution
A capacity control valve design incorporating a pressure-sensitive valve and a differential pressure valve that opens communication passages between the control pressure, suction pressure, and discharge pressure ports, allowing for rapid fluid exhaustion and maintaining equal pressures post-startup, ensuring efficient operation by stabilizing piston strokes and maintaining maximum displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single pressure-sensitive valve is used to exhaust liquefied fluid from the control chamber, then the valve structure is simple, but the startup responsiveness is slow and the fluid exhaustion is insufficient
Solution Approach 1:
The single pressure-sensitive valve is divided into two separate valves: a first pressure-sensitive valve and a second pressure-sensitive valve. Each valve has its own valve body, valve seat, and pressure-sensitive chamber configuration. This segmentation allows both valves to operate simultaneously during startup to rapidly exhaust liquefied fluid from the control chamber, improving startup responsiveness while maintaining relatively simple individual valve structures
Solution Approach 2:
The two pressure-sensitive valves are combined within the same valve housing and share common components such as the spring mechanism and housing structure. The first and second pressure-sensitive chambers are both connected to the control chamber, and their outlets merge into the suction chamber. This merging allows the system to achieve enhanced fluid exhaustion capability while avoiding complete duplication of all components
2Productivity
If the suction pressure is lowered after startup to maintain maximum displacement, then the operational efficiency is improved, but the pressure-sensitive valve cannot open due to insufficient surrounding pressure, causing differential pressure imbalance and piston wobble
Solution Approach 1:
The pressure control function is segmented between two independent pressure-sensitive valves. The first pressure-sensitive valve responds to higher pressure conditions and opens when the surrounding pressure is sufficient, while the second pressure-sensitive valve responds to lower pressure conditions. This segmentation allows the system to maintain pressure balance stability across different operating conditions while preserving operational efficiency
Solution Approach 2:
Both pressure-sensitive valves operate based on feedback from the surrounding pressure in the pressure-sensitive chamber. When suction pressure drops after startup, the pressure-sensitive chambers detect this change and automatically adjust the valve states. The feedback mechanism ensures that at least one valve remains open to maintain pressure balance, preventing piston wobble while allowing the system to operate at maximum displacement
3Stability of the object's composition
If the control pressure and suction pressure are maintained at the same pressure after startup, then the maximum displacement state is maintained, but the pressure-sensitive valve remains closed due to low suction pressure, preventing pressure equalization
Solution Approach 1:
The pressure equalization function is divided between two pressure-sensitive valves with different opening characteristics. The first valve handles pressure equalization when suction pressure is higher, while the second valve handles pressure equalization when suction pressure is lower. This segmentation ensures that pressure equalization capability is maintained across the full range of operating conditions while preserving maximum displacement state stability
Solution Approach 2:
The system utilizes changes in pressure parameters to control valve operation. When suction pressure decreases after startup, the pressure-sensitive chambers detect this parameter change and trigger the appropriate valve to open. This parameter-based control allows the system to automatically adapt to different pressure conditions, maintaining both maximum displacement stability and pressure equalization capability
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 enhances startup responsiveness by quickly exhausting liquefied fluid and maintains operational efficiency by stabilizing control pressures, preventing differential pressure-induced wobbling and ensuring maximum displacement state stability.
Implementation Method 1
a pressure-sensitive body 160 that is disposed in the third valve chamber 140 to apply a biasing force to the main valve body 151 in a valve opening direction of a main valve according to a surrounding fluid pressure
Implementation Method 2
a solenoid 180 that exerts a driving force on the main valve body 151
Data Source
AI summary
A capacity control valve V includes a valve housing provided with a Pc port, a Pd port and a Ps port; a main valve body that includes a main valve portion which comes into contact with and separates from a main valve seat 10a to close and open a communication between a Pd port and the Pc port using a driving force of a solenoid; a pressure-sensitive valve capable of opening and closing, depending on a surrounding pressure, a first communication passage through which the Pc port and the Ps port are communicable with each other; and a differential pressure valve capable of opening and closing, depending on a pressure difference, a second communication passage through which the Pc port and the Ps port are communicable with each other.