Electronic Expansion Valve Geometry for Precise Small-Flow Control
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Solution Overview
Problem
Conventional electronic expansion valves struggle to finely adjust refrigerant flow in small flow ranges due to a basal part of the valve body being parallel to the refrigerant flow path, limiting the variation of the opening area and making precise control of refrigerant flow difficult.
Innovation Solution
The electronic expansion valve features a valve body with a variable throttle portion and a stepping motor, where the side surface of the valve portion is shaped to maintain a constant opening degree ratio, allowing the opening area to increase at a fixed ratio when moved, thereby ensuring a constant variation ratio of refrigerant flow, enabling precise adjustment of refrigerant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the basal part of the valve body is parallel to the refrigerant flow path, then the valve structure is simple, but the opening area cannot vary sufficiently to enable fine adjustment of refrigerant flow
Solution Approach 1:
The valve body's side surface is designed with a curved shape instead of being parallel, creating a conical or tapered configuration. This curvature enables the opening area to vary continuously as the valve body moves axially, allowing fine adjustment of refrigerant flow while maintaining manufacturing feasibility through standard machining processes.
2Adaptability or versatility
If the opening area increases greatly with respect to the minimum movement range, then the valve has sufficient control range, but it becomes difficult to increase or decrease the refrigerant flow only slightly
Solution Approach 1:
The valve body is designed to move dynamically along the axial direction, with its position determining the opening area. The curved side surface ensures that small axial movements result in proportional changes in opening area, enabling both large-range control and fine-adjustment capabilities through the same mechanical movement.
Solution Approach 2:
The opening area parameter is changed continuously through axial movement of the valve body. The curved geometry transforms linear displacement into proportional area changes, allowing the system to achieve both wide control range and fine adjustment precision by varying the valve position parameter.
3Manufacturing precision
If the valve body is repeatedly moved forwardly or backwardly to finely adjust the opening degree, then the refrigerant flow can be adjusted, but the operation becomes complex and time-consuming
Solution Approach 1:
The curved side surface of the valve body creates a direct, monotonic relationship between axial position and opening area. This eliminates the need for repeated back-and-forth movements, as a single continuous movement in one direction provides smooth, predictable control over the refrigerant flow, simplifying the operation while maintaining precision.
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 refrigerant flow, improving the air-conditioning performance by stabilizing the operation and enabling accurate adjustment of refrigerant flow in both small and large opening degree ranges.
Implementation Method 1
a stepping motor that moves the valve body in accordance with a pulse number
Data Source
AI summary
An electronic expansion valve includes a valve body, a valve seat, and a stepping motor. A valve portion is formed at a forward end of the valve body. The valve seat forms a variable throttle portion between the valve portion and the valve seat by allowing the valve body to move in an axial direction. The stepping motor moves the valve portion in accordance with a pulse number. At least one part of a side surface of the valve portion is shaped so that an opening degree ratio becomes constant.