Expansion Valve Power Element Laser Welding for Compact Downsizing
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Solution Overview
Problem
Conventional expansion valves with built-in thermo-sensitive mechanisms require further downsizing to reduce external dimensions and production costs, as they have a large number of closely-packed parts, and existing welding methods like TIG welding generate excessive heat, affecting the diaphragm's performance.
Innovation Solution
The expansion valve employs a power element with a pressure operation chamber enclosed by an upper cover member, a receiving member, and a diaphragm, where the outer peripheral parts are joined using laser welding, reducing the outer diameter by setting the distance from the diaphragm's fulcrum to the welding area to 0.2-1.0 mm, and the power element is fixed within a cylindrical part using caulking, allowing for a smaller diameter and reduced production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If TIG welding is used to join the upper cover member, diaphragm, and receiving member, then the parts can be securely connected, but the heat generated affects the diaphragm's performance and prevents further downsizing
Solution Approach 1:
The patent changes the welding method from TIG welding to laser welding, which fundamentally alters the thermal parameters of the joining process. Laser welding concentrates heat in a smaller area and reduces total heat input, enabling the power element to be downsized while maintaining connection strength and preventing thermal damage to the diaphragm.
2Volume of moving object
If the power element diameter is reduced for downsizing, then the expansion valve becomes more compact and cost-effective, but the welding area becomes too small for conventional TIG welding
Solution Approach 1:
The patent replaces the mechanical TIG welding system with a laser welding system. This substitution enables welding of the reduced-size power element components, as laser welding can effectively join small parts with precise heat control, making downsizing manufacturable.
3Volume of moving object
If the distance from the diaphragm fulcrum to the welding area is reduced, then the power element diameter can be smaller, but the welding heat may still affect the diaphragm
Solution Approach 1:
The patent optimizes the distance parameter from the diaphragm fulcrum to the welding area to be 0.2-1.0 mm, combined with using laser welding. This parameter optimization, together with the welding method change, allows the power element to be downsized while the concentrated heat of laser welding prevents thermal diffusion to the diaphragm, maintaining its performance.
4Volume of moving object
If more parts are disposed in a closely-contact state, then the external dimension can be reduced, but the manufacturing complexity and difficulty increase
Solution Approach 1:
The patent merges the upper cover member, diaphragm, and receiving member into a compact integrated power element structure. By combining these components with optimized spacing and laser welding, the invention achieves close-part arrangement for downsizing while maintaining manufacturability through the advanced welding process.
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 approach enables a more compact expansion valve design with reduced production costs, as the smaller power element diameter allows for a caulking structure, eliminating the need for screwing and stabilizing the valve, thus enhancing performance and reducing thermal effects on the diaphragm.
Implementation Method 1
a thin plate-like diaphragm elastically deformed by received pressure
Implementation Method 2
Outer peripheral parts of the upper cover member, the diaphragm, and the receiving member are joined with a welding part formed by laser welding
Implementation Method 3
The pressure operation chamber formed with the upper cover member and the diaphragm encloses an heat-sensitive gas
Data Source
Figure 1A~2
Figure 3A~3B
Figure 4~5B
AI summary
An expansion valve has a valve main body 10, a valve member 40, and a power element 100. The power element 100 includes a diaphragm 130 sandwiched between an upper cover member 110, and a receiving member 120. Outer peripheries of the upper cover member 110, the diaphragm 130, and the receiving member 120 are joined by laser welding. The distance from a fulcrum position of the diaphragm 130 to an outer periphery of the power element 100 is set to be a distance obtained by adding 0.2 mm to 1.0 mm to the length dimension of the welding part formed by laser welding. The assembled power element 100 is inserted into a cylindrical part 12 provided at an upper part of a valve main body 10, and is fixed by a caulking part 12a formed by caulking-processing, thereby to reduce the size of the power element 100.