Impact Tool Anvil Support and Ball Retention for Compact Output Design
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Solution Overview
Problem
Existing impact drivers face issues with a long manipulatable sleeve length that prevents the shortening of the output shaft protrusion and anvil rattling, leading to a less compact design and vibration of the bit during rotation.
Innovation Solution
A tool holding apparatus with a flat spring externally mounted on the output shaft, allowing the manipulatable sleeve to be shorter while preventing ball fall-out, and axial support using two ball bearings to directly hold the anvil, reducing rattling and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a manipulatable sleeve is used to press balls to prevent them from falling out, then the balls are retained in the through holes, but the sleeve becomes relatively long in the axial direction and the output shaft protrusion length cannot be shortened
Solution Approach 1:
The patent changes the retention mechanism from axial (using a long sleeve) to radial/directional (using a fall-out prevention part with a specific shape that engages with the balls). The fall-out prevention part has a shape that allows it to engage with the balls when they protrude, preventing them from falling out through the through holes without requiring a long axial sleeve.
Solution Approach 2:
The fall-out prevention part is divided into a retention part and a pressing part. The retention part prevents ball fall-out through a specific geometric engagement, while the pressing part applies force to the balls. This segmentation allows each part to perform its function efficiently without requiring excessive length.
2Ease of operation
If a manipulatable sleeve is used to press balls, then the balls can be pressed to protruding positions, but the overall length of the tool holding apparatus becomes larger
Solution Approach 1:
The fall-out prevention part combines multiple functions: it prevents ball fall-out through its geometric shape, presses the balls to protruding positions through its pressing part, and guides the balls during operation. By merging these functions into a single integrated component rather than separate elements, the overall length of the tool holding apparatus is reduced.
3Speed
If a bearing is used to axially support the anvil, then the anvil can rotate smoothly, but a clearance is created between the bearing and anvil causing the anvil to rattle
Solution Approach 1:
The patent introduces an intermediary element (such as a retaining ring or positioning structure) between the bearing and the anvil. This intermediary fills the clearance gap, preventing the anvil from rattling while still allowing smooth rotation through the bearing. The intermediary acts as a mediator that maintains both rotational smoothness and positional stability.
4Adaptability or versatility
If clearance exists between the bearing and anvil, then the anvil can rotate with some freedom, but the bit at the tip of the anvil vibrates during rotation
Solution Approach 1:
The patent applies preliminary anti-action by pre-positioning the anvil using retaining structures that prevent excessive movement and rattling before rotation begins. The anvil is preliminarily constrained in the axial direction by the retaining ring or positioning structure, which eliminates clearance-induced instability and prevents bit vibration during subsequent rotation operations.
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
The solution allows for a more compact tool design by shortening the output shaft protrusion and effectively inhibits anvil rattling and bit vibration, enhancing operational stability.
Implementation Method 1
An elastic body biases the ball toward the protruding position
Implementation Method 2
The elastic body may be a flat spring that is externally mounted on (around) the output shaft on an outer (radially outer) side of the ball
Data Source
AI summary
An impact tool (1; 1A) includes a spindle (12) rotated by a motor (10) and a hammer (70) rotated by the spindle. The hammer is designed to impact an anvil (14) in a rotational direction. A case (8) houses the hammer. A bearing (78A, 78B) is disposed between the hammer case and the anvil. An O-ring (84) is disposed between the anvil and the bearing.