Trigger Lever Block Portion for Sensor Accuracy and Dust Sealing
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Solution Overview
Problem
The existing working machines face challenges in maintaining high sensor detection accuracy for trigger levers due to housing interference, which can lead to low accuracy and the entry of foreign matters like dust into the housing.
Innovation Solution
The design incorporates a trigger lever with a block portion of a solid revolution shape that extends through a through hole in the housing, maintaining a constant narrow clearance with the housing edges, preventing foreign matter entry and improving detection accuracy by using a sensor within the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the trigger lever is arranged to extend through the through hole to be located inside and outside the housing, then the sensor detection accuracy is improved, but foreign matters such as dust may enter the housing through a gap between the peripheral edge of the through hole and the trigger lever
Solution Approach 1:
The trigger lever is designed with a specific geometric shape (block portion with circular cross-section) that creates uniform clearance distribution around the through hole perimeter. This local geometric optimization ensures that the clearance is consistently narrow at all angular positions, preventing foreign matter entry while maintaining detection accuracy.
Solution Approach 2:
The trigger lever incorporates a block portion with a circular cross-sectional shape that rotates about the rotation axis. This curved geometry ensures that the peripheral edge of the through hole maintains a constant narrow clearance with the trigger lever surface throughout rotation, effectively preventing foreign matter accumulation while allowing smooth sensor detection.
2Ease of operation
If the trigger lever is made to rotate through various positions, then the ease of operation is improved, but the clearance between the peripheral edge of the through hole and the trigger lever may be enlarged, facilitating entry of foreign matters
Solution Approach 1:
The trigger lever features an asymmetric geometry where the block portion has a circular cross-section that is asymmetric relative to the through hole shape. This asymmetric design creates a self-compensating clearance mechanism that maintains narrow gaps at all rotational positions, allowing full range of motion while preventing foreign matter entry.
Solution Approach 2:
The circular cross-sectional shape of the block portion creates a curved surface that maintains constant distance from the through hole peripheral edge throughout rotation. This curved geometry ensures that the clearance remains narrow and uniform regardless of the trigger lever's angular position, enabling easy operation without foreign matter contamination.
Data Source
AI summary
A working machine may include a working unit, a prime mover configured to drive the working unit, a housing that supports the working unit and houses the prime mover, a trigger lever extending through a through hole defined in the housing so as to be located inside and outside the housing and configured to be manipulated by a user, a sensor configured to detect a movement of the trigger lever, and a control unit configured to control the prime mover based on a detection result by the sensor. The trigger lever may be rotatably supported by the housing via a rotation shaft. The trigger lever may include a block portion that has a shape of a substantially solid of revolution about a rotation axis of the trigger lever. A peripheral edge of the through hole may include a facing edge that faces an outer circumferential surface of the block portion.