Limit Switch One-Direction Assembly via Inverted Shaft Insertion
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Solution Overview
Problem
Conventional limit switch assembly is labor-intensive, resulting in low productivity due to the need for lateral insertion of the shaft or bearing and fixation of the cam unit with a jig.
Innovation Solution
A limit switch design where the cam unit is attached to a rotating shaft and inserted through a cylindrical bearing section, allowing for assembly from one direction without a jig, with the cam unit's outer diameter being smaller than the attachment hole, facilitating easy assembly and retention within the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the shaft or bearing is laterally inserted and the cam unit is fixed with a jig, then the assembly structure is stable, but the assembly process becomes labor-intensive and productivity decreases
Solution Approach 1:
Instead of laterally inserting the shaft or bearing into the head case, the invention inverts the assembly direction by inserting the shaft vertically from the top of the head case. The cam unit is then attached to the leading end of the shaft and inserted through the attachment hole, eliminating the need for lateral insertion and jig fixation.
Solution Approach 2:
The invention applies nesting by placing the cam unit inside the head case through the attachment hole. The cam unit with outer diameter smaller than the attachment hole inner diameter can be inserted through the hole and retained within the head case, creating a nested structure that simplifies assembly.
2Ease of manufacture
If the cam unit outer diameter is smaller than the attachment hole inner diameter, then the cam unit can be inserted through the attachment hole without jig fixation, but the cam unit may become loose in the attachment hole
Solution Approach 1:
The invention introduces a bearing as an intermediary component between the cam unit and the attachment hole. The bearing has an inner diameter larger than the cam unit outer diameter, providing a secure fit. The bearing is press-fit into the attachment hole, acting as a mediator that ensures reliable retention while allowing the cam unit to rotate smoothly.
Solution Approach 2:
The invention applies local quality by making the bearing inner diameter locally larger than the cam unit outer diameter at the insertion interface. This localized dimensional difference ensures easy insertion while the bearing's outer diameter matches the attachment hole inner diameter for secure retention, creating different dimensional relationships at different locations.
Data Source
AI summary
A limit switch having a housing having a box, an attachment hold made in a side surface of the box, having a cylindrical bearing section, a rotating shaft rotatably inserted through the cylindrical bearing section, a cam unit provided in a leading end portion of the rotating shaft, and an operation lever provided in the other end portion of the rotating shaft. Rotational action of the operation lever is converted into vertical action by the cam unit in the box. A contact of a switch main body accommodated in and fixed to the housing is opened and closed. An outer diameter of the cam unit is smaller than an inner diameter of the attachment hole.