Electronic Expansion Valve Using Differential Pressure for Precise Flow
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Solution Overview
Problem
Existing electronic expansion valves in refrigeration systems lack precise control over fluid flow, particularly at large pressure differences, and cannot be fully closed or fully opened, limiting their applications and requiring large magnetic forces or additional sensors.
Innovation Solution
An electronic expansion valve design that utilizes the pressure difference between the inlet and outlet to create a differential pressure force, combined with a magnetic force from a solenoid coil, to control fluid flow, allowing for a wider range of applications and eliminating the need for pressure sensors, with a biasing member providing a spring force and a throttling element for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a large magnetic force is provided by the solenoid coil to allow the expansion valve to open at large pressure differences, then the valve can open fully, but the valve can only be controlled between completely closed and completely open positions, losing precise control capability
Solution Approach 1:
The patent introduces a differential pressure force as an intermediary that assists the magnetic force in overcoming the biasing force. The pressure difference between inlet and outlet creates a force that acts on the armature, enabling the valve to open at large pressure differences without requiring an excessively large magnetic force, thereby maintaining control precision across the full range of operation.
2Reliability
If the expansion valve is designed to fully close the fluid path, then complete closure is achieved, but a central orifice remains open even at full displacement, preventing full closure
Solution Approach 1:
The patent segments the fluid path control by introducing a throttling element with a throttling cone that can be positioned to close different portions of the fluid path. The throttling cone, with its conical surface, allows progressive closure of the fluid path segments, enabling complete closure of the central orifice that a simple armature displacement cannot achieve.
3Ease of operation
If temperature or pressure sensors are used to adjust the expansion valve opening, then precise fluid flow control is achieved, but the system complexity and cost increase
Solution Approach 1:
The patent enables the expansion valve to control its own opening position by utilizing the differential pressure force generated by the system's own operation. The pressure difference between inlet and outlet automatically creates a force that assists the magnetic force in controlling the armature position, eliminating the need for external temperature or pressure sensors to adjust the valve.
4Adaptability or versatility
If the valve is designed for precise fluid flow control, then application versatility is improved, but the valve cannot function as a pressure relief valve
Solution Approach 1:
The patent designs the expansion valve to perform multiple functions: precise fluid flow control through magnetic and differential pressure force regulation, and pressure relief through the differential pressure force mechanism. When the pressure difference becomes excessively large, the differential pressure force automatically increases to open the valve, providing inherent pressure relief functionality without requiring a separate pressure relief valve.
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 enables precise control of fluid flow, allows the valve to function as a pressure relief valve, and reduces production costs by integrating components within a tube, ensuring safe operation and optimal flow rates without additional sensors.
Implementation Method 1
the solenoid coil provides a magnetic force on the armature towards an opening direction to allow a fluid flow from the inlet to the outlet if the solenoid coil is provided with an electric current
Implementation Method 2
the pressure difference between the inlet pressure and the outlet pressure provides a differential pressure force on the armature towards an opening direction to allow a fluid flow from the inlet to the outlet
Implementation Method 3
the biasing member provides a biasing force on the armature towards a closing direction to stop a fluid flow from the inlet to the outlet
Data Source
AI summary
An electronic expansion valve (1) is provided, comprising an inlet (9), an outlet (8), an armature (2), a stop member (3), a biasing member (4) and a solenoid coil (12). The biasing member (4) provides a biasing force on the armature (2) towards a closing direction while the solenoid coil (12) may be provided with a current to provide a magnetic force on the armature (2) towards an opening direction. It is intended to provide an electronic expansion valve that may be controlled more precisely and has a higher safety. To this end the pressure difference between the inlet pressure and the outlet pressure provides a differential pressure force on the armature (2) towards an opening direction to allow a fluid flow from the inlet (9) to the outlet (8), and furthermore the armature (2) is displaced away from the stop member (3) to allow a fluid flow from the inlet (9) to the outlet (8) if the sum of the magnetic force and the differential pressure force on the armature (2) exceeds the biasing force. The invention furthermore relates to a refrigeration system comprising such an electronic expansion valve as well as a method for calibrating such an electronic expansion valve.