Plunger Switch With Cushioning And Ridged Contacts
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Solution Overview
Problem
Conventional plunger switches for indicating door positions in home appliances are prone to breakage from slamming doors and suffer from oxidation issues at low voltage operations, leading to incorrect position indication.
Innovation Solution
A plunger switch design featuring a cylindrical switch body with biasing elements and radially projecting contact elements with ridged surfaces to ensure proper alignment and oxidation cleanup, along with a retention clip for secure mounting, preventing plunger strike and facilitating oxidation removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plunger is allowed to strike the bottom of the switch housing when the door is slammed shut, then the door position can still be indicated, but the plunger switch breaks and becomes unusable
Solution Approach 1:
The patent applies beforehand cushioning by providing a cushioning element positioned between the plunger and the bottom of the switch housing. When the door is slammed shut and the plunger strikes, the cushioning element absorbs the impact energy, preventing the plunger from breaking while still allowing the switch to indicate the door position. This resolves the contradiction by protecting the plunger's structural integrity while maintaining reliability.
2Use of energy by moving object
If the switch operates at low voltage, then energy consumption is reduced, but oxidation cannot be burned off at the electrical contacts and the switch operation is hindered
Solution Approach 1:
The patent converts the harmful effect of oxidation into a beneficial self-cleaning mechanism. The contact elements are designed with ridged surfaces that, when pressed together, mechanically scrape and remove oxidation from the contact surfaces. This allows the switch to operate reliably at low voltage without requiring high voltage to burn off oxidation, thus reducing energy consumption while maintaining operational reliability.
Solution Approach 2:
The contact elements perform self-service by automatically cleaning their own surfaces through the ridged surface design. When the plunger actuates the switch, the contact elements press together and the ridges mechanically remove oxidation buildup, ensuring continuous reliable operation without external intervention or additional energy input.
3Reliability
If the contact elements are designed with ridged surfaces for oxidation cleanup, then contact reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by providing ridged surfaces only on the contact elements where oxidation removal is needed, rather than complicating the entire switch structure. The ridges are localized to the specific areas where electrical contact occurs, allowing simple manufacturing processes for the bulk of the components while adding oxidation-resistant features only where necessary, thus balancing reliability improvement with ease of manufacture.
Data Source
AI summary
A plunger switch comprises a switch body housing a first contact element, a second contact element and an elongate plunger. The first contact element is partially housed in the switch body and extends out for operative communication with a circuit. The second contact element is movable along a longitudinal axis of the switch body and is aligned to contact the first contact element through movement. The elongate plunger is movable along the longitudinal axis of the switch body, and is able to be completely recessed in the switch body. Movement of the plunger in a first direction facilitates contact between the first and second contact elements. The contact elements contact at contact portions. At least a pair of the contact portions may have ridged surfaces that are oriented so as to have intersecting points at contact and configured to perform oxidation cleanup. At least a pair of the contact portions may include silver nitride.