Variable Displacement Compressor Back-Pressure Relief Passage
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Solution Overview
Problem
Conventional variable displacement compressors face issues with foreign matter entering the back-pressure chamber, which can hinder the operation of the spool and affect the compressor's performance.
Innovation Solution
A variable displacement compressor design that includes a back-pressure relief passage with a throttle portion, connecting the intermediate supply passage between the first control valve and the check valve with the suction chamber, and a second control valve with a spool that moves in response to pressures in the back-pressure chamber and the upstream discharge passage to control the opening degree of the discharge passage, ensuring that foreign matter flows into the suction chamber rather than the back-pressure chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pressure release passage is opened to maximum to allow refrigerant flow, then the discharge capacity is improved, but foreign matter can intrude into the back-pressure chamber and hinder spool operation
Solution Approach 1:
The passage is segmented into two separate passages: a discharge passage for refrigerant flow and a communication passage for pressure equalization. This segmentation allows the discharge passage to remain open for maximum productivity while the communication passage remains closed to prevent foreign matter intrusion, thus resolving the contradiction between discharge capacity and spool operation reliability.
Solution Approach 2:
A separate communication passage acts as an intermediary mechanism that provides pressure equalization between the back-pressure chamber and suction chamber without allowing foreign matter to enter. This intermediary passage enables the system to maintain pressure balance necessary for spool operation while keeping the discharge passage open for maximum refrigerant flow.
2Ease of operation
If the through-hole for shaft portion insertion is formed in the dividing member, then the spool can move freely to control the pressure release passage, but foreign matter can flow into the back-pressure chamber via the through-hole
Solution Approach 1:
The original single passage with a through-hole is segmented into two separate passages: the discharge passage for refrigerant flow and the communication passage for pressure equalization. This segmentation eliminates the through-hole that allowed foreign matter intrusion while preserving the spool's ability to move freely for pressure control.
Solution Approach 2:
The harmful function of the through-hole (allowing foreign matter intrusion) is extracted and removed from the system. The necessary function (pressure equalization) is achieved through a separate communication passage that does not compromise spool movement or allow foreign matter entry.
3Reliability
If the first control valve is closed to prevent backflow, then the check valve prevents refrigerant flow back to the first control valve, but refrigerant still flows into the valve chamber via the valve hole
Solution Approach 1:
The communication passage serves as an intermediary that provides a controlled path for pressure equalization between chambers without allowing uncontrolled refrigerant flow into the valve chamber. This intermediary mechanism maintains backflow prevention reliability while controlling refrigerant flow paths.
Solution Approach 2:
The refrigerant flow paths are segmented into distinct passages: the discharge passage controlled by the second control valve and the communication passage for pressure equalization. This segmentation prevents uncontrolled refrigerant flow into the valve chamber while maintaining effective backflow prevention.
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 effectively prevents or suppresses the intrusion of foreign matter into the back-pressure chamber, allowing the spool to operate satisfactorily and maintaining the compressor's performance by ensuring that foreign matter is directed into the suction chamber with the refrigerant.
Implementation Method 1
a spool that moves in response to pressures in the back-pressure chamber and the upstream discharge passage to control the opening degree of the discharge passage
Implementation Method 2
a back-pressure relief passage with a throttle portion, connecting the intermediate supply passage between the first control valve and the check valve with the suction chamber
Data Source
AI summary
Provided is a variable displacement compressor capable of preventing intrusion of foreign matter into a second control valve. A variable displacement compressor 100 is equipped with a first control valve 300 controlling the opening degree of a supply passage 145, a check valve 350, a second control valve 400 controlling the opening degree of a discharge passage 146, and a back-pressure relief passage 147. The second control valve 400 has a back-pressure chamber 410 communicating with an intermediate supply passage 145b1, a valve chamber 420 in which a valve hole 103d and a discharge hole 431a are open and which constitutes a part of the discharge passage 146, a dividing member 430 dividing the back-pressure chamber 410 and the valve chamber 420 from each other, and a spool 440. In a state in which the first control valve 300 closes the supply passage 145 and in which a valve seat side end surface 442a of a valve portion 442 of the spool 440 is spaced away from a valve seat 103f to a maximum degree, an end wall side end surface 442b of the valve portion 442 abuts an end wall 432 of the dividing member 430, whereby communication between the valve chamber 420 and the back-pressure chamber 410 via a through-hole 432a of the end wall 432 is cut off.