Gear Case Expansion Prevention for Vibration Power Tools
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Solution Overview
Problem
Existing electric power tools with vibration mechanisms, such as vibration driver drills, are prone to damage from external impacts due to direct transmission of forces to the gear case, leading to potential cracking and increased costs and size due to the need for additional reinforcing members.
Innovation Solution
Incorporating a ring-shaped expansion prevention portion on the tubular portion of the gear case that fits externally and prevents expansion, eliminating the need for additional members by integrating the expansion prevention function into the existing stop member, which also restricts bearing movement and facilitates assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reinforcing members are added to the front end of the gear case to prevent damage from impact, then the damage resistance is improved, but the number of components increases and the cost increases
Solution Approach 1:
The patent merges the damage prevention function with the existing stop member by integrating a ring-shaped protrusion into the stop member's structure. This protrusion fits into a groove on the gear case's front end, creating a unified component that both stops the gear case and prevents impact damage, thereby eliminating the need for separate reinforcing members and reducing overall component count
Solution Approach 2:
The stop member is designed to perform multiple functions: it acts as a stop to limit gear case movement, serves as a mounting structure for the vibration switching lever, and incorporates the ring-shaped protrusion that provides impact resistance. This multi-functional design eliminates the need for dedicated reinforcing members, reducing component count while maintaining damage resistance
2Reliability
If reinforcing members are added to the front end of the gear case to prevent damage from impact, then the damage resistance is improved, but the axial length increases which inhibits downsizing
Solution Approach 1:
The damage prevention structure is merged into the stop member itself through the ring-shaped protrusion that fits into a groove on the gear case. This integration eliminates the need for separate reinforcing members that would extend the axial length, achieving impact protection while maintaining a compact overall size
Solution Approach 2:
The ring-shaped protrusion is nested within the stop member's structure, fitting into a groove on the gear case's front end. This nested configuration allows the damage prevention feature to be contained within the existing component boundaries rather than adding external extensions, thereby preventing axial length increase
3Ease of manufacture
If the gear case is screwed only from the front, then the assembly is simple, but the front end is vulnerable to impact damage causing cracking
Solution Approach 1:
The ring-shaped protrusion on the stop member fits into a groove on the gear case's front end, creating a protective structure that absorbs and distributes impact forces before they can cause cracking. This preventive structure is built into the assembly, providing damage protection while maintaining the simple single-side screwing configuration
Solution Approach 2:
The protective feature is merged into the stop member structure rather than being a separate element. The ring-shaped protrusion integrates the impact resistance function into the existing stop member, maintaining assembly simplicity while enhancing damage resistance
Data Source
AI summary
An electric power tool includes a housing, a motor, a deceleration mechanism, a final output shaft, a vibration mechanism, a vibration switching member, a stop member, and an expansion prevention portion. The vibration mechanism provides a vibration in an axial direction to the final output shaft. The vibration switching member is accommodated in a slit axially disposed on a front end of a tubular portion and moved back and forth in the slit by an operation from outside to switch on and off actuation of the vibration mechanism. The stop member is installed on the front end of the tubular portion to cover the slit. The expansion prevention portion is disposed on the stop member and is brought in contact with an outer periphery of the front end of the tubular portion to prevent the front end of the tubular portion from expanding,