Bit Retention Sleeve Structure for Compact, Low-Vibration Power Tools
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Solution Overview
Problem
Existing impact drivers face issues with a long manipulatable sleeve length that protrudes from the tool holding apparatus, leading to a less compact design, and anvil rattling during rotation due to clearance in the axial support structure, causing bit vibration.
Innovation Solution
A tool holding apparatus with a manipulatable sleeve that uses a flat spring to bias balls into a protruding position, preventing them from falling out, and a dual-bearing axial support structure to directly hold the anvil, reducing rattling and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fall out prevention part is added to cover the balls when the manipulatable sleeve is slid to the advanced position, then the balls are prevented from falling out, but the manipulatable sleeve becomes relatively long in the axial direction and the length by which the output shaft protrudes cannot be shortened
Solution Approach 1:
The fall out prevention function is extracted from the manipulatable sleeve and implemented as a separate flat spring component. The flat spring is disposed independently around the output shaft and provides the ball retention function without requiring the manipulatable sleeve to extend further, thus resolving the contradiction between reliability and length.
Solution Approach 2:
The flat spring acts as an intermediary component between the balls and the manipulatable sleeve. It provides the necessary retention force to prevent ball fallout while allowing the manipulatable sleeve to maintain a compact length, mediating between the conflicting requirements of security and compactness.
2Ease of operation
If a bearing is used to axially support the anvil in the hammer case, then the anvil is supported, but a clearance is created between the bearing and the anvil causing the anvil to rattle during rotation and the bit to vibrate
Solution Approach 1:
The clearance that initially causes rattling is converted into a beneficial feature by allowing the anvil to float axially. This floating capability enables the anvil to self-adjust and absorb impact forces, transforming the harmful clearance into a mechanism that reduces vibration and rattling during operation.
Solution Approach 2:
The anvil support system transitions from a static fixed support to a dynamic floating support. The anvil is allowed to move axially within the bearing clearance, creating a dynamic system that can absorb vibrations and adapt to operational forces, thereby reducing rattling and bit vibration.
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 protrusion length of the output shaft 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 flat spring may have a ring shape with a division portion (break) such that the flat spring has two ends (opposing ends) in the circumferential direction
Data Source
AI summary
A power tool includes an anvil (14) operably driven by a motor (10); an insertion hole (91) defined the anvil, into which a bit is insertable; a through hole (92) extending radially from the insertion hole; a ball (93) disposed in the through hole; and a manually-movable sleeve (99) mounted around on the anvil and being axially slidable relative to the anvil. At a retracted position, the manually-movable sleeve presses the ball radially inwardly. At an advanced position, the manually-movable sleeve releases the pressing of the ball. A flat spring (97) is configured to bias the ball radially inwardly. The manually-movable sleeve has a length such that the flat spring is exposed at the advanced position.