Capacity Control Valve Using Pc-Ps Balance for Compact Precision
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Solution Overview
Problem
The existing capacity control valve for variable displacement compressors requires a pressure sensitive body to enhance precision, leading to an increased number of parts and a larger size.
Innovation Solution
A capacity control valve with a CS valve that controls the communication between the control port and suction port using a solenoid-driven valve element and a spring bias, allowing for Pc-Ps control without a pressure sensitive body, thereby reducing the number of parts and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensitive body is provided to enhance precision for controlling the discharge amount, then the precision is improved, but the number of parts is increased and the valve size is enlarged
Solution Approach 1:
The invention extracts and eliminates the pressure sensitive body from the system by implementing Pc-Ps control. The control pressure is directly regulated by controlling the opening degree of the valve element, which balances electromagnetic force and pressure differential force, removing the need for separate pressure sensing components while maintaining control precision.
Solution Approach 2:
The invention replaces the mechanical pressure sensitive body with a force balance mechanism. The valve element directly balances electromagnetic force (Fsol) and pressure differential force (FP) to control the valve opening degree, substituting the mechanical pressure sensing system with an electromagnetic-force balance system that achieves the same control function without additional parts.
2Measurement precision
If a pressure sensitive body is provided to enhance precision for controlling the discharge amount, then the precision is improved, but the valve size is enlarged
Solution Approach 1:
The invention extracts and eliminates the pressure sensitive body from the system by implementing Pc-Ps control. The control pressure is directly regulated by controlling the opening degree of the valve element, which balances electromagnetic force and pressure differential force, removing the need for separate pressure sensing components while maintaining control precision.
Solution Approach 2:
The invention merges the pressure sensing function into the valve element itself. The valve element simultaneously performs flow control and pressure sensing functions by directly responding to the pressure differential between control pressure Pc and suction pressure Ps, eliminating the need for separate pressure sensitive bodies and reducing overall valve size.
3Speed
If Pd-Pc control is used to promptly perform pressure adjustment, then the response speed is improved, but precision for controlling the discharge amount is reduced
Solution Approach 1:
The invention changes the control parameter from discharge pressure Pd to suction pressure Ps in the force balance equation. By controlling the valve opening degree through balancing electromagnetic force and the pressure differential between control pressure Pc and suction pressure Ps, the system achieves both rapid response (inherent in electromagnetic control) and high precision (through direct pressure differential sensing on the valve element).
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 configuration allows for precise control of the control pressure by balancing electromagnetic and spring forces, reducing the need for a pressure sensitive body and enhancing the valve's downsizing while maintaining precision.
Implementation Method 1
a valve element is moved in the axial direction by electromagnetic force generated in a solenoid
Implementation Method 2
a spring that biases the valve element in a direction opposite to a driving direction of the solenoid
Data Source
AI summary
A capacity control valve capable of being downsized with the small number of parts is provided. A capacity control valve includes a valve housing provided with a suction port through which a suction fluid of suction pressure Ps passes, and a control port through which a control fluid of control pressure Pc passes, a valve element configured to be driven by a solenoid, a spring that biases the valve element in a direction opposite to a driving direction of the solenoid, and a CS valve formed by a CS valve seat and the valve element and configured to open and close a communication between the control port and the suction port in accordance with a movement of the valve element. The control pressure Pc is controlled by opening and closing the CS valve.