Switch With Coil Spring Shear Force Prevents Contact Welding
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Solution Overview
Problem
Conventional switches for opening and closing contacts with a pushing operation require a large number of parts and assembly steps, leading to high costs and limited miniaturization due to the need for a large contacting area to prevent wear, and they cannot instantaneously open and close contacts.
Innovation Solution
A switch design featuring a base, a supporting terminal, a housing, a movable contact piece made of band-shaped conductive material, a plunger, and a coil spring with a forced dissociation bent portion that allows for instantaneous contact opening and closing with reduced parts and assembly steps, using the spring force to invert the movable contact piece and exert a shear force to prevent contact welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional switch structure with movable terminal and multiple springs is used, then contact reliability is maintained, but number of parts and assembly steps increase and cost increases
Solution Approach 1:
The patent combines the holding spring and returning spring functions into a single coil spring with a forced dissociation bent portion. This single spring performs multiple functions: it holds the movable contact piece in the initial position, returns it after actuation, and provides the shear force through the bent portion. This merging reduces the number of parts from multiple springs to one, simplifying assembly and reducing cost while maintaining contact reliability.
Solution Approach 2:
The coil spring is designed to perform multiple functions simultaneously. The main body of the spring provides elastic support and returning force, while the forced dissociation bent portion provides shear force to prevent contact welding. This multi-functional design eliminates the need for separate components, reducing device complexity while ensuring reliable contact operation.
2Device complexity
If movable terminal follows button operation speed, then simple structure is maintained, but contact opening/closing speed is slow and large contacting area is required
Solution Approach 1:
The patent introduces a cam mechanism that converts the slow, linear button pressing motion into rapid rotational movement of the movable contact piece. The cam's profile is designed to accelerate the contact piece during the latter portion of the button stroke, enabling instantaneous contact opening/closing. This dynamic mechanism allows the contact speed to exceed the button operation speed, resolving the contradiction between structural simplicity and contact speed.
Solution Approach 2:
The cam mechanism transforms the one-dimensional linear motion of the button press into two-dimensional motion involving both linear displacement and rotational movement of the movable contact piece. This dimensional transformation enables the contact to open and close rapidly by leveraging the rotational component, which provides instantaneous separation without requiring large contacting areas.
3Stability of the object's composition
If conventional spring support structure is used, then contact holding is achieved, but number of parts increases and miniaturization is limited
Solution Approach 1:
The patent merges the holding and returning spring functions into a single coil spring, and integrates the shear force provision through the forced dissociation bent portion. This consolidation reduces the space required for spring components and their mounting structures, enabling miniaturization while maintaining stable contact holding through the multi-functional spring design.
4Reliability
If large contacting area is used to prevent contact wear, then contact durability is improved, but switch miniaturization is prevented
Solution Approach 1:
The cam mechanism enables instantaneous contact opening and closing, significantly reducing the duration of contact wear. By minimizing the time contacts are engaged and disengaged, the effective wear per operation is reduced, allowing smaller contacting areas to achieve the same durability as larger contacts in conventional slow-operating switches.
Solution Approach 2:
The forced dissociation bent portion of the coil spring actively exerts shear force on the movable contact piece during operation. This shear force prevents contact welding by mechanically separating the contacts, converting the potential harmful effect of contact adhesion into a beneficial preventive action. This allows for smaller contacting areas without sacrificing durability, as the shear force protects against wear-related failures.
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 design reduces the number of parts and assembly steps, enables miniaturization, and effectively prevents contact welding by using the coil spring's shear force and bending moment, resulting in a more reliable and cost-effective switch.
Implementation Method 1
at least one coil spring preferably including a forced dissociation bent portion at one end and being rotatably supported by the plunger; wherein the plunger is movable up and down to slidably move the one end of the coil spring while pressure contacting a second end of the movable contact piece to invert the movable contact piece
Implementation Method 2
exerts a shear force on the movable contact of the movable contact piece
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
There is provided a switch including a supporting terminal 21 assembled to a base 10; a movable contact piece 30, made of a band-shaped conductive material bent to a substantially J-shaped cross section, having a movable contact 31 at one end and having an intermediate portion rotatably supported by a rotation receiving portion 24 of the supporting terminal 21; a plunger 40 accommodated so as to be movable up and down in an internal space formed by fitting a housing 60 to the base 10; and a coil spring 50 including a forced dissociation bent portion 53 at one end and being rotatably supported by the plunger 40. In particular, the plunger 40 is moved up and down to slidably move one end of the coil spring 50 while pressure contacting the other end edge of the movable contact piece 30 to invert the movable contact piece 30 and contact or separate the movable contact 31 to and from a fixed contact 26, and to lock a distal end of a forced dissociation bent portion 53 to the other end edge of the movable contact piece 30 and exert a shear force on the movable contact 31 of the movable contact piece 30.