Shiftable Hand Tool Gearbox With Locking Sleeve Alignment
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Solution Overview
Problem
Existing hand-held power tools with switchable gearboxes lack a compact and reliable design that ensures safe and straightforward gear shifting, leading to potential misalignment and inefficiencies.
Innovation Solution
A hand-held power tool with a drive unit featuring a switchable gearbox housed in a gearbox housing with a sleeve-shaped clutch housing and a locking sleeve, where the switching element is arranged in a cross-sectional plane perpendicular to the axis of rotation, and a locking sleeve is used to secure the switching element in specific positions, along with a gearbox cover that engages form-fittingly and has centering and support ribs for stable assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switchable gearbox is arranged in a gearbox housing without a locking sleeve, then the structure is simpler, but the switching element cannot be securely locked in gear positions leading to misalignment and unreliable gear shifting
Solution Approach 1:
The locking sleeve is nested within the clutch housing and surrounds the switching element, creating a compact nested structure where the locking sleeve can radially extend to lock the switching element in gear positions without adding significant external dimensions to the gearbox assembly
Solution Approach 2:
The locking sleeve acts as an intermediary component between the switching element and the clutch housing, providing a mechanical locking interface that secures the switching element in selected gear positions while allowing smooth transitions between gears
2Manufacturing precision
If the switching element is arranged without a predetermined cross-sectional plane arrangement, then the design is more flexible, but misalignment between components occurs reducing efficiency
Solution Approach 1:
The locking sleeve is pre-positioned in the clutch housing with its axial end facing the switching element, establishing a predetermined cross-sectional plane arrangement before final assembly, which guides the switching element into correct alignment and ensures precise gear positioning
Solution Approach 2:
The locking sleeve's radial extension and engagement with the switching element automatically self-align the components during assembly, with the locking sleeve's geometry guiding the switching element into the correct position without requiring additional alignment fixtures or complex assembly procedures
3Stability of the object's composition
If the gearbox cover is attached without form-fitting engagement and positioning ribs, then assembly is faster, but the connection is less secure and components may become misaligned
Solution Approach 1:
The positioning ribs are provided at specific local positions on the locking sleeve's axial end, creating localized form-fitting engagement points with corresponding recesses in the clutch housing that ensure precise positioning and stable assembly without requiring complex fastening mechanisms throughout the entire gearbox cover
Data Source
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AI summary
In a hand-held power tool with a drive unit for rotating a tool holder (140) about an associated axis of rotation (199), wherein the drive unit comprises at least one drive motor and a switchable gearbox (120), wherein the switchable gearbox (120) is arranged in a gearbox housing (122) with a clutch housing (220) that is at least partially sleeve-shaped and a gearbox cover (210) attached thereto, wherein a switching element (240) is provided for switching the switchable gearbox (120) between at least two different gear stages, and wherein a locking sleeve (230) for locking the switching element (240) in at least a first and a second switching position (205, 206) is arranged in the clutch housing (220), the switchable gearbox (120) forms a cross-sectional plane perpendicular to the axis of rotation (199) at least in the first switching position (205) of the switching element (240).in which the locking sleeve (230) is arranged at least partially between the transmission cover (210) and the shifting element (240), and the shifting element (240) is arranged at least partially between the locking sleeve (230) and the clutch housing (220).