Impact Tool Axial Length Reduction via Bearing Stabilization
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Solution Overview
Problem
Existing impact tools face challenges in reducing their size while maintaining operability, particularly in the axial direction, which affects their compactness and usability.
Innovation Solution
The impact tool design incorporates a motor, a striker drivable by the motor, an anvil with a radial projection, a hammer case, bearings surrounding the anvil shaft, a ring member in contact with the bearing, and a stopper engaging with the hammer case and ring member to prevent rearward movement, thereby reducing the tool's size by stabilizing the bearing and ring member positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the bearing and ring member are allowed to move freely, then the assembly is simpler and easier to manufacture, but the axial length increases and compactness is reduced
Solution Approach 1:
The bearing support structure is segmented into multiple functional components: the bearing itself, the ring member with axial groove, and the stopper element. This segmentation allows each component to perform a specific function (support, locate, constrain) thereby reducing the overall axial length while maintaining manufacturability through modular assembly
Solution Approach 2:
The ring member is nested within the bearing assembly, with the axial groove in the ring member receiving the stopper. This nesting arrangement allows the stopper to be housed within the existing bearing structure rather than adding external constraint components, thereby reducing axial length while providing the necessary positioning function
2Reliability
If the ring member is constrained from moving rearward, then the bearing position is stabilized and torque transmission is improved, but the assembly complexity increases
Solution Approach 1:
The ring member's axial groove is designed to automatically receive and retain the stopper through its own structural feature, eliminating the need for separate retention mechanisms. The groove geometry itself provides the constraint function, allowing the system to achieve reliable bearing positioning through self-contained design rather than additional complex constraint components
Solution Approach 2:
Instead of using a complex active constraint mechanism to prevent rearward movement, the design inverts the approach by using a passive geometric feature (the axial groove) that naturally receives and retains the stopper. This inversion from active constraint to passive retention simplifies the overall assembly while maintaining reliable bearing position stability
Data Source
AI summary
A technique reduces an increase in the size of an impact tool. An impact tool includes a motor, a striker drivable by the motor, an anvil including an anvil shaft to receive a tip tool, and an anvil projection protruding radially outward from a rear end of the anvil shaft to be struck by the striker in a rotation direction, a hammer case accommodating the striker, a bearing held in the hammer case and surrounding the anvil shaft, a ring member at least partially facing a front surface of the anvil projection and in contact with a rear end face of the bearing, and a stopper engaging with the hammer case and the ring member to reduce moving of the ring member rearward.