Spring-Biased Chuck Assembly for Multi-Size Bit Locking
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Solution Overview
Problem
Existing chuck assemblies for rotary power tools either suffer from the limitations of continuously variable designs or are restricted to a single standard size, lacking flexibility in accommodating multiple standard bit shanks without the disadvantages of continuously variable chucks.
Innovation Solution
A chuck assembly design featuring a body with sizing groove sets, a collar with a stepped portion, and a spring-biased engagement mechanism that allows for quick and secure attachment of multiple standard sized bit shanks, including features like helical grooves and locking assemblies to prevent inadvertent loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a continuously variable chuck is used to accept a continuous range of bit sizes, then adaptability is improved, but device complexity and weight increase
Solution Approach 1:
The chuck assembly is segmented into discrete size categories using multiple bit holder receptacles, each configured for a specific bit size. This segmentation allows the system to provide adaptability for different bit sizes while maintaining the simplicity of fixed-size receptacles, avoiding the complexity of continuously variable chucks.
Solution Approach 2:
The chuck assembly achieves multi-functionality by incorporating multiple bit holder receptacles that can accommodate different standard bit sizes (e.g., 1/4-inch, 3/8-inch, 7/16-inch hex bits). This universal design allows a single tool to perform multiple functions without requiring a continuously variable mechanism.
2Device complexity
If a single standard size bit holder is used, then device complexity is reduced, but adaptability deteriorates
Solution Approach 1:
Multiple bit holder receptacles for different standard bit sizes are merged into a single chuck assembly. Each receptacle maintains its simple, fixed-size structure, but their combination within one tool body provides adaptability for multiple bit sizes without increasing individual component complexity.
3Reliability
If a locking assembly is added to prevent inadvertent loosening, then reliability is improved, but device complexity increases
Solution Approach 1:
The locking assembly operates on a self-service principle where the user's own rotational action of inserting or removing the bit automatically engages or disengages the locking mechanism. The spring-biased pawl and ratchet teeth provide automatic locking without requiring additional controls or complex mechanisms.
Solution Approach 2:
The spring-biased pawl acts as an intermediary element between the bit holder receptacle and the bit. It provides the locking function through simple mechanical interaction with the bit's peripheral surface, adding reliability without requiring a complex locking system.
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
Enables rapid and secure attachment of tool bits with various standard sizes, providing audible and tactile feedback, and preventing unintentional loosening, thus enhancing usability and reliability.
Implementation Method 1
a spring biasing the collar such that the stepped portion is biased into engagement with the plurality of jaws
Implementation Method 2
a first set of threads coupled for co-rotation with the collar and engageable with a second set of threads on the body such that rotation of the collar relative to the body causes the collar to move axially along the body
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A chuck assembly (410) for a rotary power tool includes a body (434) rotatable about a central axis, the body including a plurality of openings and a first set of threads (467), a plurality of jaws (38) received within the plurality of openings in the body; a collar (442) surrounding the body, the collar including a stepped portion configured to engage the plurality of jaws to limit radial movement of the plurality of jaws, a second set of threads (562) coupled for co-rotation with the collar and engageable with the first set of threads on the body such that rotation of the collar relative to the body causes the collar to move axially along the body, and a spring (496) biasing the collar such that the stepped portion is biased into engagement with the plurality of jaws.