Temperature-Dependent Switch One-Sided Spot Welding
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Solution Overview
Problem
Existing temperature-dependent switches face challenges with deformation during riveting, leading to unreliable operation and complex manufacturing processes, and soldered connections are prone to failure under heat stress during welding.
Innovation Solution
The use of one-sided spot welding to connect supply lines to the switch's connection surfaces after assembly, ensuring a mechanically strong, electrically safe, and temperature-resistant connection without the need for protective layers, allowing for flexible connection configurations and integration of series resistors or self-holding resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If riveting is used to connect supply lines to connection surfaces, then mechanical strength is improved, but housing deformation occurs leading to unreliable switch operation
Solution Approach 1:
The patent replaces the mechanical riveting system with an electrical resistance welding system. Instead of using rivets to mechanically connect the supply line inner end to the connection surfaces, the invention uses controlled electrical current to create spot welds that join the tabs to the connection surfaces. This substitution eliminates the deformation problems associated with mechanical riveting while maintaining strong mechanical and electrical connection.
2Ease of manufacture
If soldering is used to connect supply lines to connection surfaces, then ease of manufacture is improved, but connection failure occurs under heat stress during welding
Solution Approach 1:
The patent changes the thermal parameters of the connection process by using resistance welding instead of soldering. The welding process uses controlled electrical current to generate localized heat only at the joint interface, rather than applying widespread thermal stress through soldering. This parameter change allows the connection to withstand subsequent heat stress during device welding without failing.
3Reliability
If protective layers are added to prevent deformation, then reliability is improved, but device complexity and manufacturing time increase
Solution Approach 1:
The patent extracts and eliminates the protective layer requirement by changing the fundamental connection method. Instead of adding protective layers to prevent deformation during riveting, the invention removes the riveting process entirely and uses resistance welding, which does not require protective layers. This extraction simplifies the device structure and manufacturing process while maintaining reliability.
4Productivity
If spot welding is used to connect supply lines to connection surfaces, then manufacturing time is reduced, but connection strength may be insufficient without protective layers
Solution Approach 1:
The patent applies preliminary action by designing the tabs with specific geometric features (protrusions extending from the inner end) before the welding process. These pre-formed tabs are positioned to optimize contact with the connection surfaces, ensuring that when spot welding is applied, maximum strength is achieved. The preliminary shaping of tabs eliminates the need for protective layers while maintaining connection strength.
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 method prevents deformation and ensures reliable operation while simplifying the manufacturing process and eliminating the risk of connection failure during heat stress, enabling the switch to be used as an SMD component with improved heat transfer and current-dependent switching.
Implementation Method 1
the inner end of the supply line is welded to the at least one connection surface by at least one spot weld
Implementation Method 2
electric spot welding being mentioned as the method
Implementation Method 3
a bimetal part is usually provided in the switching mechanism, which suddenly deforms from its low-temperature position to its high-temperature position when its switching temperature is reached
Implementation Method 4
The welding current thus flows from one of the two welding electrodes partly through the upper part and partly through the lower part
Data Source
Figure 1
Figure 2~4
Figure 5
AI summary
A temperature-dependent switch (10) has on the outside of its housing a first and at least a second terminal surface (22, 23) for the galvanic connection of leads (46, 47), and inside the housing a temperature-dependent switching mechanism that establishes or opens an electrically conductive connection between the two terminal surfaces (22, 23) depending on its temperature. The leads (46, 47) are connected to the terminal surfaces (22, 23) at their inner ends (48, 49) by spot welding on one side (Fig. 2).