Switch Assembly Securing Pin and Channel Locking Mechanism
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Solution Overview
Problem
Existing switch assemblies for power equipment, such as lawn tractors, often experience unintended position changes from 'ON' to 'OFF', leading to potential failure due to lack of secure retention mechanisms, resulting in reduced pull force over time.
Innovation Solution
A switch assembly with a securing arrangement featuring a cylindrical securing pin and a channel with narrowing regions, which engages with the pin to prevent voluntary position changes and maintain the switch in selected positions, utilizing a shaft body with legs and a channel to enhance locking force and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional push button or plunger type switch is used without a securing arrangement, then the switch structure is simple and easy to manufacture, but the switch experiences unintended position changes from ON to OFF leading to potential failure
Solution Approach 1:
The shaft body is divided into functional segments including a pull knob portion for user actuation, a shaft portion that moves between positions, and an upper end with spaced legs forming a channel. This segmentation allows each part to perform its specific function while maintaining overall structural integrity and reliability.
Solution Approach 2:
The securing arrangement with the cylindrical pin and narrowing regions is nested within the channel formed by the shaft legs. The pin engages with the narrowing regions to lock the shaft in selected positions, creating a compact nested structure that prevents unintended position changes without significantly increasing overall device complexity.
2Duration of action of moving object
If a securing arrangement with cylindrical pin and narrowing regions is added to prevent position changes, then the switch maintains consistent pull force throughout product life, but the manufacturing complexity increases
Solution Approach 1:
The channel in the shaft body includes localized narrowing regions at specific positions along the shaft. These narrowing regions are formed with precise local geometry to engage the cylindrical securing pin, ensuring consistent pull force is maintained throughout the product life while the rest of the shaft maintains its simple tubular structure for ease of manufacture.
3Reliability
If the shaft body includes spaced legs forming a channel with securing arrangement, then the switch prevents voluntary position changes and reduces failure likelihood, but the device complexity increases
Solution Approach 1:
The channel formed by the spaced legs of the shaft body is asymmetric in cross-section, with narrowing regions at specific locations rather than being uniformly circular or symmetric. This asymmetric geometry allows the cylindrical securing pin to engage at specific positions, preventing voluntary position changes while maintaining a relatively simple shaft body structure.
Data Source
AI summary
A switch apparatus includes a housing having an interior chamber for supporting a portion of a shaft body. The shaft body has a portion extending from the housing coupled to a pull knob such that the shaft body and pull knob are selectively located from a first position to a second position. The shaft body further comprises spaced first and second legs having a securing arrangement disposed within a channel formed by the legs, the securing arrangement comprises a restricted region formed about a portion of the legs in the channel and a securing pin fixedly attached to the housing, such that the securing pin engages the restricted region when the shaft body and pull knob transition from the first position to the second position.