Rotary Switch Centering Means Prevent Shaft Seizure
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Solution Overview
Problem
State-of-the-art rotary switches face issues with the cover not being correctly centered on the body, leading to the rotating shaft seizing and breaking, and difficulty in setting visual indicators to the zero position due to the screwing mechanism preventing a fixed and repeatable position of the cover.
Innovation Solution
A rotary switch design with centering means, such as a flange and seat, and threaded coupling with a nut screw, ensures coaxial alignment and secure assembly, while the indicator's stem connects with the shaft through a slot-in portion, allowing for easy adjustment and zeroing of visual signalling means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cover is screwed directly onto the body through threading, then the assembly is secure and safety regulations are met, but the cover cannot be correctly centered on the body, causing the rotating shaft to seize and break
Solution Approach 1:
The assembly is divided into three distinct components: the body, the cover, and a separate centering means (flange). This segmentation allows the centering function to be independently provided by the flange, while the covering and securing functions are provided by the cover and its threaded engagement with the body, respectively. The flange acts as an intermediate element that resolves the conflict between secure assembly and precise centering.
Solution Approach 2:
The centering means (flange) acts as an intermediary element between the body and the cover. It mediates the relationship between these two components by providing precise centering during assembly, allowing the cover to be correctly positioned before being secured by threading. This intermediary element eliminates the direct conflict between secure attachment and precise alignment.
2Reliability
If the cover is screwed onto the body, then the assembly is fixed, but it becomes difficult to set the visual indicators on the zero position due to inability to obtain a fixed and repeatable position
Solution Approach 1:
The centering means (flange) performs the preliminary action of establishing a fixed and repeatable position of the cover relative to the body before the final securing operation. By providing precise centering during the assembly process, it enables the visual indicators to be accurately positioned at the zero mark before the cover is permanently fixed by threading, thus resolving the conflict between fixed assembly and ease of adjustment.
3Device complexity
If the rotating shaft passes through the body and is supported by the cover, then the structure is simple, but the shaft inevitably tends to seize and break when the cover is not correctly centered
Solution Approach 1:
The centering means (flange) provides beforehand cushioning by preventing misalignment between the cover and the body before the rotating shaft operates. By ensuring correct centering during assembly, it prevents the conditions that would lead to shaft seizure and breakage, thus protecting the shaft without requiring complex protective mechanisms during operation.
Data Source
AI summary
A rotary switch comprising a body housing inside itself a rotating shaft operatively connected to a valve or actuator. The switch further comprises a cover, associated to the body by threaded coupling means, provided with an indicator swivelling integrally with the shaft, so that it enables visual signalling of the angular position and/or operating status of the shaft. The switch comprises centering means, mechanically distinct from the threaded coupling means, which ensure the centering of the cover in relation to the body and the coaxial relation between the cover and the rotating shaft.