Variable Displacement Compressor Bleed Valve Dynamics
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Solution Overview
Problem
Variable displacement compressors face inefficiencies due to the deterioration of the second control valve's responsiveness, leading to prolonged startup times and reduced displacement, as the cross-sectional area of the bleed passage is fixed, causing liquefied refrigerant to vaporize and increase pressure in the crank chamber.
Innovation Solution
The compressor design includes a second control valve with a valve hole, valve chamber, first and second valve portions, and a valve seat member, where the second valve portion divides the valve chamber into a bleed chamber and backpressure chamber, allowing for adjustable cross-sectional areas and fluid communication between them, preventing foreign matter ingress and enhancing responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the cross-sectional area of the bleed passage is made small to improve operating efficiency, then the operating efficiency of the compressor is improved, but the discharge rate of liquefied refrigerant during startup is reduced, causing prolonged startup time
Solution Approach 1:
The patent applies the dynamics principle by making the cross-sectional area of the bleed passage variable rather than fixed. The second control valve adjusts the opening degree of the bleed passage dynamically based on operating conditions: during startup, the opening is enlarged to rapidly discharge liquefied refrigerant and reduce startup time; during normal operation, the opening is reduced to maintain high operating efficiency. This dynamic adjustment resolves the contradiction between startup performance and operating efficiency.
2Loss of energy
If the cross-sectional area of the bleed passage is fixed at a small value, then the operating efficiency is improved, but the responsiveness of the second control valve deteriorates due to foreign matter accumulation
Solution Approach 1:
By making the bleed passage opening variable through the second control valve, the system can periodically or conditionally enlarge the opening to prevent foreign matter accumulation. This dynamic adjustment maintains high operating efficiency during normal operation while periodically improving responsiveness by allowing foreign matter to be flushed out, thus resolving the contradiction between efficiency and reliability.
Solution Approach 2:
The second control valve can be designed to periodically adjust the bleed passage opening, creating periodic flushing actions that prevent foreign matter accumulation. This periodic action maintains the small opening for efficiency during most of the time while occasionally enlarging the opening to clear foreign matter, thereby maintaining responsiveness without sacrificing overall operating efficiency.
3Loss of time
If the cross-sectional area of the bleed passage is enlarged to improve startup performance, then the startup time is reduced, but the operating efficiency deteriorates
Solution Approach 1:
The patent uses the dynamics principle by implementing a control mechanism that adjusts the bleed passage cross-sectional area based on the operational state. During startup, when liquefied refrigerant accumulation is detected or anticipated, the second control valve enlarges the bleed passage opening to rapidly discharge the liquid and reduce startup time. Once the compressor reaches normal operation, the valve reduces the opening to maintain high operating efficiency. This state-dependent dynamic adjustment resolves the contradiction between startup performance and operating efficiency.
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 allows for rapid discharge of liquefied refrigerant during startup, reducing startup time and improving responsiveness of the second control valve, ensuring efficient displacement control and minimizing the impact of foreign matter, thus enhancing the compressor's operational efficiency.
Implementation Method 1
the inclination angle of the swash plate decreases as the pressure in the crank chamber rises. This decrease of the inclination angle decreases the stroke length of a piston thereby to decrease the displacement of the compressor
Implementation Method 2
a valve seat member, wherein the valve seat member is disposed in the valve chamber and provided separately from a compressor housing forming the valve chamber
Data Source
AI summary
The variable displacement compressor has a suction-pressure region, a discharge-pressure region and a crank chamber. The compressor includes a supply passage, a bleed passage and a control valve that adjusts cross-sectional area of the bleed passage. The control valve includes a valve chamber, a valve portion and a valve seat member. The valve portion is disposed in the valve chamber for dividing the valve chamber into a bleed chamber, a backpressure chamber and a communication passage. The bleed chamber forms a part of the bleed passage. The backpressure chamber communicates with the supply passage. The communication passage is formed between an outer circumferential surface of the valve portion and an inner circumferential surface of the valve chamber for providing fluid communication between the bleed chamber and the backpressure chamber. The valve seat member is disposed in the bleed chamber and provided separately from a compressor housing forming the valve chamber.