Pneumatic Tool Drive Arrangement Reducing Gear Jamming
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Solution Overview
Problem
Conventional pneumatic power tools face issues with spindle and gear jamming due to high rotational speeds, and their design limits the effective length of the spindle, making them bulky and inflexible for use in limited spaces.
Innovation Solution
The drive arrangement features a reduced joint length of the drive and feed gears through an intermediate feed gear that is interchangeably connected to the motor output shaft, allowing for high rotational speeds without jamming, and includes a clutch sleeve with a torque limiting spring and a retraction mechanism to manage gear ratios and prevent jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the spindle and gears rotate at high speeds to improve productivity, then drilling efficiency increases, but the risk of jamming increases and reliability decreases
Solution Approach 1:
The patent employs dynamic elements including a spring-loaded clutch mechanism that automatically engages and disengages based on rotational speed, and a movable feed gear that can be positioned at different locations along the spindle. These dynamic features allow the system to adapt to varying operational conditions, preventing jamming while maintaining high-speed productivity.
Solution Approach 2:
The patent introduces an intermediary clutch mechanism between the motor and the drive gear, and a movable feed gear that acts as an intermediary between the drive gear and the spindle. These intermediary elements buffer the direct transmission of high-speed rotation, reducing the likelihood of jamming while preserving productivity.
2Length of moving object
If the joint length of drive and feed gears is reduced to increase spindle active length, then tool compactness improves, but gear ratio flexibility deteriorates
Solution Approach 1:
The feed gear is designed to be movable along the spindle rather than fixed, allowing it to be positioned at different locations to achieve different gear ratios. This dynamic positioning capability maintains gear ratio flexibility while keeping the overall gear joint length short, thus preserving both spindle active length and adaptability.
Solution Approach 2:
The drive system is segmented into distinct functional components: a drive gear, a movable feed gear, and a clutch mechanism. This segmentation allows each component to be optimized independently - the gears can be compact while the feed gear's position provides the necessary ratio flexibility.
3Device complexity
If conventional fixed gear arrangements are used, then device complexity is low, but spindle active length is limited and tool head becomes bulky
Solution Approach 1:
The patent introduces a movable feed gear that can be repositioned along the spindle, adding only minimal complexity while dramatically increasing the active length of the spindle. The spring-loaded clutch mechanism similarly adds simple dynamic functionality without significant complexity.
Solution Approach 2:
The drive gear and feed gear are arranged coaxially around the spindle in a nested configuration, with the clutch mechanism integrated into this arrangement. This nested layout minimizes the radial and axial space required, keeping the tool head compact while maximizing the spindle's active length.
Data Source
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AI summary
A drive arrangement in a pneumatic power tool comprising a pneumatic motor (13) with an output shaft (16), a spindle (11) for mounting a cutting element, which spindle externally includes both a thread (21) and an axial groove (22), wherein the drive rotation of the spindle (11) is driven by a drive gear (23) that is engaged with the axial groove (22) on the spindle (11) and drivingly connected to the output shaft (16) so as to rotate at a constant speed with respect to the output shaft (16), and wherein a feed gear (25) is threaded upon said spindle (11), which feed gear (25) may be rotated with respect to the spindle (11) in order to advance and retract said spindle (11). The feed gear (25) is driven by one intermediate feed gear (29), which intermediate feed gear (29) is interchangeably drivingly connectable to the output shaft (16) via a first and a second gear connection, respectively, so as to advance or retract the spindle (11).