Dual-Snap Temperature Switch for Shock-Resistant Self-Holding
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Solution Overview
Problem
Existing temperature-dependent switches with self-holding functions are prone to mechanical shocks and require complex designs for precise thermal hysteresis, making them susceptible to unintended switching and difficult to manufacture effectively.
Innovation Solution
A temperature-dependent switch design featuring two snap parts with distinct switching and switch-back temperatures, where the second snap part maintains the switch in an open position after cooling, preventing unintended closure due to mechanical shocks, and allowing easy reset by cooling below the second switch-back temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single snap part is used for switching, then the switch structure is simple, but the switch-back temperature cannot be precisely controlled below room temperature
Solution Approach 1:
The snap part is divided into two functionally independent sections: a switching section that operates at the first switching temperature to open the circuit, and a self-holding section that maintains the open state until the second switch-back temperature is reached. This segmentation allows each section to be optimized for its specific function, achieving precise temperature control while maintaining structural simplicity.
2Reliability
If a temperature-independent bistable spring element is used for self-holding, then the switch remains open after cooling, but the switch is susceptible to mechanical shocks and requires complex reset procedures
Solution Approach 1:
The temperature-independent mechanical self-holding mechanism is replaced with a temperature-dependent self-holding mechanism. The second snap part uses thermal hysteresis properties to maintain the open state automatically based on temperature conditions, eliminating the need for mechanical intervention during reset and reducing susceptibility to mechanical shocks.
3Ease of repair
If the switch housing is opened for manual reset, then the switch can be reset, but contaminants can penetrate the interior and impair function
Solution Approach 1:
The switch performs its own reset function automatically when the temperature drops below the second switch-back temperature, eliminating the need for manual intervention. This self-service capability removes the requirement to open the housing for reset operations, thereby preventing contaminant ingress while maintaining full reset functionality.
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
The design ensures a reversible self-holding function that is not susceptible to mechanical shocks, simplifies manufacturing, and allows for easy cancellation of the self-holding function by cooling, improving safety and reliability.
Implementation Method 1
a temperature-dependent bimetallic snap-action disc (44) secured to the movable contact element (40) at its center (54) in such a way that, when the switch (10) is heated to a temperature above the switching temperature of the bimetallic snap-action disc (44), the bimetallic snap-action disc (44) snaps from its first configuration into its second configuration, thereby lifting the movable contact element (40) with its edge (56) from the stationary contact (48)
Implementation Method 2
The disc is designed in such a way that, when the switch (10) cools down to a temperature below the switch-back temperature of the bimetallic snap-action disc (44), the bimetallic snap-action disc (44) snaps back from its second configuration into its first configuration
Data Source
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AI summary
Temperature-dependent switch (10) comprising a first and a second stationary contact (48, 50) and at least one temperature-dependent switching mechanism (14) with a movable contact element (40), wherein the at least one switching mechanism (14) in its first switching position presses the contact element (40) against the first contact (48) and thereby establishes an electrically conductive connection between the two contacts (48, 50) via the contact element (40) and in its second switching position keeps the contact element (40) spaced apart from the first contact (48).The at least one temperature-dependent switching mechanism (14) has a first temperature-dependent snap element (30) which, upon exceeding a first switching temperature, snaps from its geometric low-temperature configuration to its geometric high-temperature configuration and, upon subsequently falling below a first reset temperature, snaps back from its geometric high-temperature configuration to its geometric low-temperature configuration. The switch (10) further has a second temperature-dependent snap element (44) which, upon exceeding a second switching temperature, snaps from its geometric low-temperature configuration to its geometric high-temperature configuration and, upon subsequently falling below a second reset temperature, snaps back from its geometric high-temperature configuration to its geometric low-temperature configuration.A snapping action of the first snap element (30) from its low-temperature geometric configuration to its high-temperature geometric configuration and/or a snapping action of the second snap element (44) from its low-temperature geometric configuration to its high-temperature geometric configuration brings at least one switching mechanism (14) from its first switching position to its second switching position. The second reset temperature is lower than the first reset temperature, and the second snap element (44) is configured to keep the contact element (40) spaced apart from the first contact (48) even if the switch (10) heats up above the first and second switching temperatures and subsequently cools down to a temperature between the first and second reset temperatures.