Eccentric Cam Limit Switch Return Mechanism
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Solution Overview
Problem
Conventional limit switches fail to return the turning lever to its original position when the turning angle reaches 90 degrees due to a lack of moment generation, as the contact surface of the cam with the cam follower is partially above the shaft center, preventing the actuator from reversing.
Innovation Solution
A limit switch design where the cam is formed such that its whole contact surface with the cam receiver is located on the cam receiver side with respect to the shaft center when no external force is applied, allowing the cam to be eccentric and generate moment when the lever is turned 90 degrees, enabling the lever to return to its original position through a biasing mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cam contact surface is positioned above the shaft center, then the structure is simple and manufacturing is easy, but the turning lever cannot return to original position when turned 90 degrees due to lack of moment generation
Solution Approach 1:
The cam contact surface is positioned asymmetrically on the cam receiver side with respect to the shaft center, rather than symmetrically above it. This asymmetric positioning ensures that when the turning lever is turned 90 degrees, the cam's contact surface remains offset from the shaft center, generating the necessary moment for the biasing member to return the lever to its original position.
2Reliability
If the cam contact surface is centered on the shaft center, then moment generation is maximized for returning, but the turning lever cannot be held stably in the actuated position
Solution Approach 1:
The cam contact surface is positioned in a specific local region on the cam receiver side of the shaft center. This localized positioning provides dual functionality: when the turning lever is actuated, the offset position generates moment for return; when the turning lever is in the actuated position, the cam geometry maintains stable contact with the cam receiver, ensuring positional stability.
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
Ensures the limit switch can return to its original position even when the turning lever is turned 90 degrees, maintaining stability and functionality by generating the necessary moment for the cam to turn back, preventing the actuator from being stuck.
Implementation Method 1
a biasing member configured to bias the displacement member and the turning lever so as to return the displacement member and the turning lever to original positions when the external force is released
Implementation Method 2
the cam receiver being pressed by the turning cam to linearly displace a position of the displacement member
Data Source
AI summary
A limit switch is provided that is returned to an original position even if a turning angle of a turning lever becomes 90 degrees. In a section perpendicular to a turning shaft, a cam is formed such that a whole contact surface of the cam with a cam receiver is located on a side of the cam receiver with respect to a shaft center of the turning shaft when the external force does not act on the turning lever.