Damped Microswitch Contact Design for High-Cycle Test Systems
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Solution Overview
Problem
Existing microswitches used in testing systems for wiring harnesses suffer from high wear and tear due to frequent switching operations, requiring precise force and distance measurements for correct installation, and often necessitate insulation between components, leading to reduced service life and increased manufacturing complexity.
Innovation Solution
A microswitch design featuring a cylindrical sleeve with an axially movable piston and contact pin, supported by two springs, where a damping spring ensures soft contact and adjustable switching point, eliminating the need for insulation and enhancing durability with conical contact tips and a plastic holding plate for improved guidance and reduced abrasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If common microswitches with insulated housing are used, then switching function is achieved, but service life is reduced due to insulation wear
Solution Approach 1:
The patent removes the insulation component entirely from the microswitch design. The housing is made conductive and integrated with the contact elements, eliminating the insulation layer that would otherwise wear out and require replacement. This extraction of the problematic insulation element directly resolves the contradiction between reliability and device complexity.
Solution Approach 2:
The patent employs composite material construction where the housing and contact elements are made from conductive materials that can withstand repeated switching operations. The use of metal or conductive polymer components creates a durable assembly that eliminates wear issues associated with insulating materials while maintaining electrical functionality.
2Manufacturing precision
If precise force and distance measurements are implemented for component insertion, then switching accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The patent incorporates a cushioning element or compliant mechanism that absorbs insertion force variations and ensures consistent contact pressure regardless of insertion precision. This pre-compliance mechanism compensates for tolerances in component positioning and force application, achieving reliable switching without requiring precise measurement and control systems.
Solution Approach 2:
The patent designs the switching mechanism to be tolerant of parameter variations in insertion force and distance. By adjusting the spring constant, contact geometry, or travel distance, the system achieves reliable switching across a range of insertion conditions, eliminating the need for precise force and distance measurements during manufacturing.
3Productivity
If the microswitch undergoes thousands of switching operations, then testing function is maintained, but wear increases significantly
Solution Approach 1:
The patent employs self-lubricating materials or self-adjusting contact surfaces that reduce wear during repeated switching operations. The contact elements are designed to automatically maintain optimal contact conditions, distributing wear evenly and preventing the accumulation of damage that would otherwise limit the number of switching cycles.
Solution Approach 2:
The patent uses curved or spherical contact surfaces instead of flat contacts. The curved geometry distributes contact pressure more evenly across the contact area, reducing stress concentration and wear at any single point. This allows the microswitch to withstand thousands of switching operations while maintaining reliable electrical contact.
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 microswitch achieves extended service life with over 500,000 switching cycles, reduced tolerance requirements, and minimal abrasion, while maintaining a stable electrical connection and easy assembly, making it suitable for high-volume manufacturing with reduced maintenance needs.
Implementation Method 1
A return spring is arranged between the base of the sleeve and the piston and moves the piston to an initial position when the microswitch is not actuated.
Implementation Method 2
A damping spring is arranged between the contact pin and an actuating cap of the piston and ensures that the contact pin gently contacts the mating contacts.
Implementation Method 3
The contact pin has a contact tip, with both the contact tip of the contact pin and the mating contacts being conical in shape.
Data Source
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AI summary
A microswitch according to the invention consists of a cylindrical sleeve in which a piston is axially movably mounted. A contact pin is also axially movably mounted within the piston. The contact pin interacts with two mating contacts spaced apart from each other in a base of the sleeve. The movement of the contact pin is assisted by two springs. A return spring is arranged between the sleeve base and the piston and moves the piston to a starting position when the microswitch is not actuated. A damping spring is arranged between the contact pin and an actuating cap of the piston and ensures that the contact pin makes soft contact with the mating contacts. To dampen the movement of the contact pin only shortly before contact with the mating contacts, the damping spring has a higher spring force than the return spring.The microswitch can be constructed with a robust metal sleeve and still requires no insulation between the plunger and the sleeve. Furthermore, the two mating contacts result in a larger contact area and improved guidance of the contact pin.