Control Valve Differential Pressure Relief for Variable Displacement Compressors
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Solution Overview
Problem
Existing control valves for variable displacement compressors experience a sudden rise in control pressure when the solenoid is turned off, leading to potential refrigerant leakage due to excessive pressure.
Innovation Solution
A control valve design that includes a differential pressure valve opening mechanism, activated when the pressure difference between the control chamber and the suction chamber reaches a preset level, to open the sub-valve and prevent or reduce sudden increases in control pressure, utilizing a solenoid, main and sub-valve elements, biasing members, and a pressure-sensing mechanism to regulate refrigerant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the solenoid is switched off to open the main valve, then the refrigerant flow rate increases, but the control pressure suddenly rises excessively
Solution Approach 1:
The sub-valve is opened in advance before the main valve opens completely, creating a pressure relief path beforehand. When the solenoid switches off and the main valve begins to open, the sub-valve is already positioned to allow excess control pressure to escape to the suction chamber, preventing sudden pressure spikes.
Solution Approach 2:
The sub-valve acts as an intermediary pressure relief mechanism between the control chamber and suction chamber. It provides a controlled escape path for refrigerant from the control chamber, mediating the pressure transition when the main valve opens and preventing direct pressure transmission to the control chamber.
2Ease of operation
If the main valve opens fully when the solenoid is turned off, then refrigerant can flow freely, but refrigerant leakage occurs due to excessive control pressure
Solution Approach 1:
The sub-valve serves as an intermediary safety mechanism that prevents excessive control pressure from reaching levels that would compromise sealing. By providing a pressure relief path to the suction chamber, it protects the main valve sealing surfaces and other critical sealing portions from pressure-induced leakage.
Solution Approach 2:
The sub-valve provides beforehand cushioning against pressure excess by establishing a pressure relief path before damage can occur. When control pressure begins to rise during main valve operation, the sub-valve opens to release excess pressure, cushioning the system against pressure spikes that would cause sealing failure.
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
Effectively prevents or reduces sudden increases in control pressure, minimizing refrigerant leakage and ensuring stable compressor operation by automatically opening the sub-valve when the pressure difference exceeds a preset threshold.
Implementation Method 1
a solenoid configured to generate a drive force in a valve closing direction of the main valve
Implementation Method 2
a first biasing member for applying a biasing force to the main valve in a valve opening direction
Implementation Method 3
a second biasing member for applying a biasing force to the sub-valve in a valve closing direction
Implementation Method 4
a differential pressure valve opening mechanism configured to open the sub-valve when a pressure difference between a control pressure in the control chamber and a suction pressure in the suction chamber becomes a preset pressure difference or larger
Data Source
AI summary
A control valve includes: a body having a main passage through which a discharge chamber and a control chamber communicate, and a sub-passage through which the control chamber and a suction chamber communicate; a main valve seat provided in the main passage; a main valve element configured to touch and leave the main valve seat to close and open a main valve; a sub-valve seat provided in the sub-passage; a sub-valve element configured to touch and leave the sub-valve seat to close and open a sub-valve; a solenoid configured to generate a drive force in a valve closing direction of the main valve; an actuating rod for transmitting the drive force of the solenoid to the main valve element and the sub-valve element; a spring for applying a biasing force to the main valve in a valve opening direction; a spring for applying a biasing force to the sub-valve in a valve closing direction; and a differential pressure valve opening mechanism configured to open the sub-valve when a pressure difference between a control pressure in the control chamber and a suction pressure in the suction chamber becomes a preset pressure difference or larger.