Neutral Position Limit Switch Head with Cam Follower
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Solution Overview
Problem
Existing neutral position limit switches require a large degree of pre-travel rotation (15-20°) of the actuator shaft before translating into linear movement, leading to increased switching/tripping time, complexity, and cost due to numerous moving parts, which can result in reliability issues.
Innovation Solution
A simplified head assembly design with a reduced number of moving parts, utilizing a cam member and follower mechanism that achieves actuation with approximately 5° of pre-travel rotation, where a rolling pin interacts with the cam member to pivot a lever and translate an actuator member linearly, reducing the number of components and assembly time while enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a traditional head assembly design with multiple moving parts is used, then the limit switch can achieve the required switching function, but the pre-travel rotation angle increases to 15-20° resulting in slower switching time
Solution Approach 1:
The patent combines the cam member and follower into a single integrated component rather than separate parts. The follower is formed as an integral part of the cam member, eliminating the need for separate mounting and reducing the number of moving parts. This merging reduces pre-travel rotation while maintaining the switching function.
Solution Approach 2:
The patent changes the geometric parameters of the cam profile to optimize the conversion from rotational to linear motion. By carefully designing the cam surface geometry, the patent achieves reduced pre-travel rotation angle (from 15-20° to approximately 5°) while maintaining adequate linear output movement for reliable switching actuation.
2Loss of time
If the pre-travel rotation angle is reduced to improve switching time, then the switching speed increases, but the head assembly requires more moving parts and becomes more complex
Solution Approach 1:
The follower is integrated as a single piece with the cam member, eliminating separate components and their associated mounting hardware. This integration reduces the number of moving parts while achieving the reduced pre-travel rotation angle needed for faster switching response.
Solution Approach 2:
The cam member is designed with distinct functional zones: a cam surface for motion conversion, a follower portion for actuation, and mounting features for secure attachment. This segmentation of functions within a single integrated component allows optimized performance without increasing part count.
3Speed
If multiple cam members with different orientations are used to reduce pre-travel rotation, then the switching performance improves, but the manufacturing cost and assembly complexity increase
Solution Approach 1:
Instead of using multiple separate cam members that require individual mounting and orientation, the patent integrates all cam functions into a single cam member with a specifically designed profile. This eliminates the need for multiple mounting operations and reduces assembly time while maintaining the required actuation speed.
Solution Approach 2:
The single cam member performs multiple functions: it converts rotational motion to linear motion, provides the necessary mechanical advantage, and enables reduced pre-travel rotation. This multi-functional design eliminates the need for multiple specialized components, simplifying both manufacturing and assembly.
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 achieves quicker switching/tripping times with reduced pre-travel rotation, lowers the complexity and cost of the head assembly, and enhances reliability by minimizing moving components, allowing for efficient operation in a compact form.
Implementation Method 1
a cam member supported on the shaft and that is rotatable in the clockwise and counter-clockwise directions responsive to rotation of the shaft, and a follower actuated by the cam member responsive to rotation of the cam member
Implementation Method 2
a rolling pin mounted to the lever portion and in contact with the cam member. The rolling pin moves along a profile of the cam member upon rotation of the cam member
Implementation Method 3
a lever portion positioned on the pivot pin and pivotable thereabout in opposing directions, and a rolling pin mounted to the lever portion and in contact with the cam member
Data Source
AI summary
A limit switch operating head includes a shaft rotatable in clockwise and counter-clockwise directions, a cam member supported on the shaft and that is rotatable in the clockwise and counter-clockwise directions responsive to rotation of the shaft, and a follower actuated by the cam member responsive to rotation thereof, with the follower including a pivot pin, a lever portion pivotable about the pivot pin, and a rolling pin mounted to the lever portion and in contact with the cam member. An actuator member contacts the lever portion and translates linearly in a first direction or second direction responsive to pivoting thereof. The rolling pin moves along a profile of the cam member upon rotation of the cam member so as to cause the lever portion to pivot, with the actuator member linearly translating in the first direction or the second direction responsive to the pivoting of the lever portion.