Shiftable Power Tool Transmission With Nested Locking Sleeve
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Solution Overview
Problem
Existing portable power tools with shiftable transmissions face challenges in achieving a compact design while ensuring secure and reliable gear shifting and locking mechanisms, which affects their operational efficiency and durability.
Innovation Solution
The design incorporates a shiftable transmission with a locking sleeve and shifting ring gear arranged in a cross-sectional plane, featuring a locking sleeve with axially oriented positioning tabs and supporting pegs, and a fixing ring to prevent rotation, along with a form-fitting connection between the clutch housing and locking sleeve, allowing for secure gear shifting and reduced overall length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the transmission is designed to be compact, then the overall length is reduced, but the reliability of gear shifting and locking mechanisms may be compromised
Solution Approach 1:
The locking sleeve is arranged within the clutch housing, and the shifting element is arranged within the locking sleeve, creating a nested configuration. The shifting ring gear is arranged in an inner receptacle formed by the locking sleeve. This nesting allows multiple functional components to occupy the same spatial envelope, reducing the overall length of the transmission while maintaining all necessary gear shifting and locking functions.
Solution Approach 2:
The patent arranges components in a cross-sectional plane perpendicular to the axis of rotation, with the locking sleeve positioned between the transmission cover and shifting element in this plane. This dimensional reorganization allows components to be stacked radially rather than only axially, compacting the transmission length while preserving functional integrity through careful spatial planning in multiple dimensions.
2Ease of operation
If the shifting element is arranged on the outer circumference of the transmission housing, then the gear shifting function is achieved, but the transmission housing becomes larger
Solution Approach 1:
The shifting element is moved from the outer circumference of the transmission housing to an inner position within the locking sleeve. The shifting ring gear is arranged in an inner receptacle formed by the locking sleeve, with the shifting element arranged within this receptacle. This nested arrangement allows the shifting function to be performed by components located inside the transmission housing rather than on its outer surface, reducing the required volume of the transmission housing.
3Reliability
If the transmission cover is fastened to the clutch housing, then the transmission structure is secured, but the assembly complexity increases
Solution Approach 1:
The locking sleeve is pre-assembled with the shifting ring gear arranged in its inner receptacle, and the transmission cover is pre-positioned relative to the locking sleeve. The form-fitting connection between the transmission cover and locking sleeve is designed to automatically align components during assembly. This preliminary arrangement of components simplifies the final assembly process, as parts are pre-configured to fit together without complex alignment procedures.
Solution Approach 2:
The transmission cover has a specific engagement geometry with the locking sleeve, featuring localized form-fitting connection surfaces and positioning features at specific locations. This localized precision engagement ensures structural security at critical connection points while allowing other areas to be simpler, balancing structural integrity with assembly ease through differentiated local design qualities.
Data Source
AI summary
A portable power tool has a drive unit for rotationally driving a tool receptacle about an axis of rotation, the drive unit having at least one drive motor and a shiftable transmission, which is arranged in a transmission housing with an at least partially sleeve-like clutch housing and a transmission cover fastened thereto. The tool includes a shifting element for shifting the shiftable transmission between at least two different gears, and a locking sleeve for locking the shifting element in at least a first and a second shifting position is arranged in the clutch housing. The shiftable transmission forms, at least in the first shifting position, a cross-sectional plane perpendicular to the axis of rotation in which the locking sleeve is arranged at least regionally between the transmission cover and the shifting element and the shifting element is arranged at least regionally between the locking sleeve and the clutch housing.