Power Tool Axial Length Reduction via Planet Carrier Integration
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Solution Overview
Problem
Existing power tools, such as drill/drivers, are not compact enough in the axial direction, limiting their usability in space-constrained applications.
Innovation Solution
The power tool design incorporates an output planet carrier that rotatably supports a portion of the anvil, allowing it to overlap with the bearing in the axial direction, and features a two-stage, two-speed transmission with a spindle lock mechanism that reduces the overall length by using an aperture with circumferentially spaced lands to contact the anvil, thereby minimizing the tool's axial length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the anvil is separately positioned from the output planet carrier, then the support structure is simpler, but the axial length of the power tool increases
Solution Approach 1:
The anvil is integrated with the output planet carrier, merging two previously separate components into one unified structure. This integration allows the anvil to be supported directly by the planet carrier's bearing, eliminating the need for separate support structures and reducing the overall axial length of the power tool while maintaining structural integrity and functionality.
Solution Approach 2:
The anvil is positioned within the output planet carrier structure, with the planet carrier enveloping and supporting the anvil. This nested arrangement allows compact positioning of components in the axial direction, reducing the tool's overall length while maintaining proper support and functionality of both the anvil and planet carrier.
2Ease of manufacture
If circumferentially spaced lands are used to contact the anvil, then the contact area is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The contact interface between the output planet carrier and the anvil is segmented into multiple circumferentially spaced lands rather than a continuous contact surface. This segmentation distributes the contact loads across discrete points, simplifying the manufacturing process by allowing for easier machining and assembly, while the multiple lands collectively provide sufficient support and stability.
Data Source
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AI summary
A power tool (10) that includes a housing assembly (12), a motor (14) received in the housing assembly, a trigger (122), an output spindle (22), a transmission (16) and a bearing (80). The transmission is received in the housing assembly and transmits rotary power between the motor and the output spindle. The transmission has an output planetary stage (52) with an output planet carrier (74). The transmission also has a member that is axially movable between a first position, which causes the transmission to operate in a first speed ratio, and a second position in which the transmission operates in a second speed ratio that is different than the first speed ratio. The bearing (80) is disposed radially between and engages both the housing assembly and the output planet carrier. The output spindle is at least partially received into the output planet carrier such that the bearing indirectly supports the output spindle.