Switch Actuator Interlock for Welded Contact Detection
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Solution Overview
Problem
Switching devices in industrial equipment can falsely indicate an open electrical connection when the contacts are welded together, posing a safety hazard due to potential slippage of the actuator, and existing solutions are either ineffective or costly.
Innovation Solution
A switching device with an actuator and plunger mechanism that prevents actuator movement when contacts are welded, using a softer material for the actuator and a harder material for the plunger to interlock and prevent slippage, providing tactile and auditory feedback when the contacts are welded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the actuator is designed to rotate freely to indicate switch state, then the ease of operation is improved, but the reliability deteriorates because the actuator can slip and falsely indicate OFF when contacts are welded
Solution Approach 1:
The patent introduces an intermediary mechanism consisting of a cam and follower that couples the actuator rotation to plunger movement. The cam profile is designed such that during normal operation, the follower rides on the cam surface allowing smooth actuator rotation. When contacts are welded, the plunger cannot move, causing the follower to engage with a different portion of the cam profile that prevents further actuator rotation, thus providing tactile feedback and preventing false indication.
2Ease of manufacture
If the actuator engagement section is made softer than the plunger engagement section, then the ease of manufacture is improved through material selection, but the reliability must be ensured that the softer material prevents slippage when welded
Solution Approach 1:
The patent applies parameter changes by selecting materials with different hardness properties for the actuator engagement section and plunger engagement section. The actuator engagement section is made of a softer material that can deform slightly under load, while the plunger engagement section is made of a harder material. This material parameter difference ensures that when the contacts are welded and force is applied, the softer actuator material deforms to engage firmly with the harder plunger material, preventing slippage and providing reliable tactile feedback.
Data Source
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AI summary
The present invention is an industrial switching device which prevents a false indication of an open electrical circuit when contacts within the switching device are welded shut. Under normal operation, an actuator is selectively moved between a first position and a second position to reciprocally move a plunger to open and close the contacts. The actuator includes an indicator of whether the switching device is in the "ON" or "OFF" state. When the contacts are welded shut, a plunger engagement section interlocks with an actuator engagement section to prevent the actuator from moving from the "ON" position to the "OFF" position. A crossbar on the plunger engagement section embeds in the actuator engagement section to prevent the actuator from sliding over the plunger. A side member on the plunger engagement section prevents the actuator from sliding around the plunger.