Temperature-Dependent Switch With Mechanical Closing Lock
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Solution Overview
Problem
Existing temperature-dependent switches fail to securely interrupt power circuits under strong vibrations and temperature fluctuations, leading to potential re-closure and consequential damage, especially in applications like electric motors.
Innovation Solution
A temperature-dependent switch with a structurally simple design featuring a closing lock using a spring washer that mechanically locks the current transfer member permanently upon initial opening, preventing re-closure due to vibrations or temperature changes, and utilizing a bistable spring disc for stable contact pressure and long-term stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switch uses a temperature-dependent bi-metal snap disc to open the circuit, then the switch can interrupt power when temperature rises above response temperature, but the switch may re-close under strong mechanical vibrations after cooling down
Solution Approach 1:
The closing lock is pre-configured with resilient tongues that can deflect and lock onto the current transfer member. When the switch opens, the resilient tongues automatically deflect and engage with the current transfer member to prevent re-closure, preparing the locking mechanism in advance before vibration occurs.
Solution Approach 2:
The resilient tongues act as an intermediary mechanical locking element between the housing and the current transfer member. This intermediary mechanism provides a positive mechanical lock that prevents direct vibration-induced re-closure of the contacts.
2Reliability
If the switch remains open after one opening operation, then safety is improved by preventing re-closure, but the device complexity increases due to additional locking mechanisms
Solution Approach 1:
The closing lock utilizes the existing movement of the current transfer member during normal switching operation to automatically engage the resilient tongues with the current transfer member. The switch's own operational movement serves to activate the locking function, eliminating the need for separate actuating mechanisms.
Solution Approach 2:
The resilient tongues are designed as simple, inexpensive elastic elements that provide the locking function through their elastic deformation. This simple structure achieves the one-time switch function without complex mechanical assemblies.
3Reliability
If a self-holding resistor is used to maintain switch open position, then the switch can stay open during operation, but the self-holding function is cancelled when the device is shut off from supply circuit
Solution Approach 1:
The patent replaces the electrical self-holding mechanism (self-holding resistor) with a mechanical locking system using resilient tongues. This mechanical substitution provides continuous holding action independent of the electrical supply circuit state.
Solution Approach 2:
The mechanical locking system automatically engages and disengages based on the switch's own operational movement, providing self-service functionality that maintains the open position without requiring external power or control.
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
Ensures secure and permanent interruption of the power circuit, enhancing safety and reliability by preventing unwanted re-closure even under strong mechanical vibrations or temperature fluctuations, thus protecting devices from overheating.
Implementation Method 1
a temperature-dependent switching mechanism having a temperature-dependent bi-metal snap disc
Implementation Method 2
a bistable spring disc, which carries a movable counter contact or a current transfer member in the shape of a contact plate
Data Source
AI summary
A temperature-dependent switch which comprises a first and a second stationary counter contact and a temperature-dependent switching mechanism having a current transfer member. The switching mechanism, depending on its temperature, either closes the switch by pressing the current transfer member against the first and the second counter contact and thereby establishing an electrically conductive connection between the two counter contacts via the current transfer member, or opens the switch by keeping the current transfer member at a distance from the first and the second counter contact and thereby interrupting the electrically conductive connection. A closing lock is provided, which keeps the switch open when it has been opened for the first time. The closing lock comprises a spring washer which directly interacts with the current transfer member and mechanically locks the latter permanently when the switch has been opened for the first time so that the switch remains permanently open.