Symmetrical Cam Switch Device for Consistent Rotary Operation
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Solution Overview
Problem
Conventional switch devices with a rotary shaft configuration for a knob result in varying operation amounts depending on the direction of operation, leading to an unfamiliar operation feel for users accustomed to traditional lever-based systems.
Innovation Solution
The design ensures equal rotational angles for the cam and knob when switching on both switch elements, regardless of operation direction, by positioning the rotary shaft centrally and using symmetrical cam configurations to maintain consistent operation amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rotary shaft is positioned closer to the base portion to involve only the operation portion in switching, then the switching operation becomes more direct, but the operation amount becomes larger and differs between operation directions
Solution Approach 1:
The cam's rotary shaft is positioned asymmetrically relative to the knob's rotary shaft, creating an offset configuration. This asymmetric arrangement allows the cam to rotate by a smaller angle while still achieving the same switching effect, and crucially, the operation amounts become equal in both pulling-up and pushing-in directions due to the symmetric positioning of pressing portions around the cam's rotary shaft
Solution Approach 2:
The cam acts as an intermediary mechanism between the knob and the switch elements. When the knob rotates, it drives the cam to rotate, which then presses the switch elements through its pressing portions. This intermediary cam mechanism decouples the direct rotation relationship, allowing for optimized operation amounts and consistent performance in both operation directions
2Ease of operation
If the rotary shaft is positioned centrally for symmetrical operation, then the operation feel becomes familiar, but the operation amounts differ when the shaft is moved to one side
Solution Approach 1:
The invention introduces asymmetry by offsetting the cam's rotary shaft from the knob's rotary shaft. This offset creates a mechanical advantage where the cam rotates through a smaller angle for the same switching effect. The symmetric positioning of the cam's pressing portions around its own rotary shaft ensures that operation amounts are equal in both directions, resolving the contradiction between familiar operation feel and operation amount equality
3Reliability
If the cam rotates by a larger angle to switch both elements, then the switching is more reliable, but the operation amount becomes unnecessarily large
Solution Approach 1:
The cam serves as an intermediary that translates the knob's rotation into controlled pressing actions on the switch elements. By positioning the cam's rotary shaft offset from the knob's rotary shaft, the mechanism achieves reliable switching with a smaller rotation angle. The cam's geometry and positioning ensure that both switch elements are activated reliably while minimizing the required rotation angle
Data Source
Figure 1
Figure 2(A)~2(C)
Figure 3
AI summary
First and second cams (9A,B) are rotated in a direction determined by a rotation direction of a knob (5) by first and second operation portions (73A,B) extending from the knob (5). A first switch element (23) is switched on when the first cam is rotated in one direction around the second shaft (X2), by a pressing portion (92) of the first cam at one side thereof. A second switch element is switched on when the second cam is rotated in the other direction around the second shaft (X2), by a pressing portion (92) of the second cam at the other side thereof. As viewed in a shaft direction of the rotary shaft (X2), (a) the first and second switch elements (23,24) and (b) the pressing portions (92,b) are respectively arranged to be symmetrical around the second shaft (X2).