Spring-Elastic Force Transmission Element for Overload Switchgear
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Solution Overview
Problem
Existing overload switching devices can inadvertently re-establish current flow after a cooling period, posing safety hazards and potential damage, especially when the bimetallic piece is pressed into its warm position due to external loads, leading to unintended reactivation of the load.
Innovation Solution
Incorporating a spring-elastic force transmission element between the actuating part and the bimetallic piece, ensuring the actuating force transmitted when pressing the button is smaller than the opening force of the bimetallic piece in its warm position, preventing direct current passage and allowing the bimetallic piece to snap back automatically, thus providing a trip-free release mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the push button is pressed directly onto the bimetallic piece to reset the overload switch, then the mechanical switching force can be applied to snap back the bimetallic piece, but the push button can be inadvertently pressed in the warm position causing unintended reactivation of the load
Solution Approach 1:
A force transmission element is introduced as an intermediary component between the push button and the bimetallic piece. This mediator transmits the resetting force only when the bimetallic piece is in the cold position, preventing direct contact and unintended reactivation when the bimetallic piece is in the warm position.
Solution Approach 2:
The force transmission element is designed to prevent the harmful action (unintended reactivation) before it can occur. When the bimetallic piece is in the warm position, the element blocks the force transmission path, making it impossible for the push button to reactivate the load regardless of how hard it is pressed.
2Reliability
If the force transmission element is designed to transmit sufficient force to reset the bimetallic piece, then reliable switching back to cold position is achieved, but the actuating force may exceed the opening force in warm position causing potential damage
Solution Approach 1:
The force transmission element is designed with specific mechanical parameters (spring constant, lever arm ratios, or gear ratios) that transform the push button force into an appropriate resetting force. The element is calibrated to provide sufficient force to snap back the bimetallic piece to the cold position while limiting the maximum force to prevent damage to the bimetallic piece or other components.
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 solution ensures reliable switching back to the cold position of the bimetallic piece, preventing accidental reactivation of the load and enhancing safety by ensuring the bimetallic piece cannot be pressed into its warm position, thus avoiding safety hazards and potential damage.
Implementation Method 1
a bimetallic piece which, when heated from a cold position, in which the gap between the gaps is electrically conductively bridged by means of a contact bridge
Implementation Method 2
a spring-elastic force transmission element is provided, which is arranged between the actuating part and the bimetallic piece in the direction of force action
Data Source
Figure 1
Figure 2
AI summary
The overload switch gear (11) has an elastically active force transmission element (39) in force effective direction. The force transmission element is arranged between an actuating part (32) and a bimetal piece (25). The actuating force of the force transmission element is smaller than the opening force. The actuating force is transferred to the bimetal piece by pressing the push button. The opening force active in the warm state of the bimetal piece.