Bimetallic Strip Ramp Guide for Thermal Trip Consistency
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Solution Overview
Problem
Significant deformation of the bimetallic strip in thermal tripping devices leads to non-repetitive tripping travel and tripping time for a given current, due to excessive slope opposing the drawer's movement, resulting in performance issues.
Innovation Solution
Incorporating a ramp at the end of the bimetallic strip, forming an angle of approximately 10° with its longitudinal direction, to guide the drawer effectively during deformation, either by bending, shearing, or adding a fixed part, ensuring consistent positioning against a stop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bimetallic strip with significant deflection is used to improve device performance, then the deflection capability is enhanced, but the tripping travel becomes non-repetitive and tripping time varies
Solution Approach 1:
A ramp element is introduced as an intermediary component between the bimetallic strip and the drawer. This ramp guides the drawer along a controlled path during the tripping motion, ensuring that the drawer follows a consistent trajectory regardless of the bimetallic strip's deflection magnitude. The ramp acts as a mediator that transforms the bimetallic strip's deformation into a standardized drawer movement, resolving the contradiction between enhanced deflection capability and consistent tripping travel.
2Reliability
If the bimetallic strip deforms significantly, then the thermal response is improved, but the slope at the end opposes the drawer movement excessively
Solution Approach 1:
The ramp introduces a new geometric dimension to the interaction between the bimetallic strip and drawer. By creating an inclined surface at a specific angle (approximately 10-15 degrees), the ramp transforms the force vector from the bimetallic strip, allowing the drawer to move along the ramp's slope rather than directly opposing the strip's end slope. This dimensional change reduces the opposing force while maintaining thermal response effectiveness.
3Reliability
If the force direction changes significantly during bimetallic strip deformation, then the thermal effect is enhanced, but the drawer cannot return properly against its stop
Solution Approach 1:
The ramp is designed to preliminarily guide the drawer along a controlled path before the drawer reaches its final position against the stop. This preliminary action ensures that the drawer is properly positioned and oriented before the tripping mechanism engages, allowing the drawer to return stably against the stop even when the bimetallic strip's force direction changes significantly during deformation.
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 design ensures repetitive tripping travel and consistent tripping times, improving device performance without altering the kinematic chain or adding components, at a low industrial cost.
Implementation Method 1
following an electrical overload, said drawer cooperating with a fixed stop relative to the housing of the device and intended to partly guide the trajectory of the drawer when moving it. The tensile force exerted by the end of the thermal bimetallic strip on the drawer
Implementation Method 2
said thermal trigger device comprising a bimetallic strip capable of cooperating with a drawer connected in an articulated manner by one of its ends to said lever so as to drive said drawer in the direction of release during deformation of the bimetallic strip following an electrical overload
Data Source
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AI summary
The device (9) has a triggering lever articulated on a plate. A bimetallic strip (10) cooperates with a slide (11). The slide is connected with the lever to drive the slide in a triggering direction during deformation of the bimetallic strip due to electrical overload. The bimetallic strip has a ramp (13) at its end cooperating with the slide. The ramp is arranged in a manner to position the slide against a stop (12) during a deformation phase of the bimetallic strip such that the stop assures guiding of the slide during its displacement.