Two-Part Drive Pinion for Compact Hand-Held Power Tools
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Solution Overview
Problem
Existing hand-held power tools, such as chainsaws and hedge trimmers, face challenges in minimizing their axial size due to the requirement for a one-piece drive pinion, which increases the overall length and exposes the tool to bending forces.
Innovation Solution
A two-part drive pinion design is implemented, where the first part has a section with the largest diameter for the gearing and the second part features a bearing seat, allowing for a stable structure without increasing size, and the parts are soldered together using a soldering ring for a secure connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a one-piece drive pinion is used, then the structural integrity is maintained, but the axial size increases and bending forces increase
Solution Approach 1:
The drive pinion is divided into two separate parts: a first part with the toothing and a second part with the bearing seat. This segmentation allows each part to be optimized independently, reducing the overall axial size while maintaining structural integrity through precise fitting and connection of the segments.
2Stability of the object's composition
If the bearing seat is enlarged for stability, then the structural stability improves, but the axial size increases due to cutter runout requirements
Solution Approach 1:
By separating the bearing seat into a distinct second part, the design allows the bearing seat to be enlarged for stability without requiring additional axial space for cutter runout. The bearing seat can be optimally sized for structural stability while the toothing section maintains its functional requirements.
Solution Approach 2:
The bearing seat is designed to extend in a direction perpendicular to the axial direction, allowing the outer diameter to be increased for stability without proportionally increasing the axial length. This dimensional redistribution enables the bearing seat to provide enhanced stability while maintaining compact axial dimensions.
3Length of moving object
If the drive pinion is shortened to reduce size, then the axial size decreases, but the bending forces on the connection point increase
Solution Approach 1:
The segmented design allows the toothing section to be positioned closer to the clutch drum, reducing the axial length. The connection point between the two parts is designed to handle bending forces, with the second part providing a stable mounting for the bearing that supports the reduced lever arm and associated bending moments.
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
This design reduces the overall size of the tool, minimizes bending forces, and provides a stable connection, enabling a compact and efficient hand-held working device.
Implementation Method 1
The soldering ring can be inserted into the receptacle during production and then melted by appropriate heating so that the two individual parts are soldered.
Data Source
Figure 1~2
Figure 3~6
AI summary
The hand-operated working device has a drive motor which drives a drive pinion for driving a tool by a clutch, where the drive pinion is rotationally connected with a drive part of the clutch. The drive pinion is constructed from two individual parts (27,28) that are connected with each other. The former individual part carries a tooth pitch and the latter individual part is connected with the clutch.