Power Tool Gearbox Clutch Angle Design

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Solution Overview

Problem

Current rotary power tools with variable speed motors and multi-stage multi-speed transmissions face challenges in reducing complexity and cost while maintaining performance.

Innovation Solution

A power tool design featuring a motor, transmission with a ring gear having opposite axial end faces, and a clutch with an annular clutch face disposed about the ring gear, where the included angle between the clutch face and the ring gear is between 95 degrees to 150 degrees, along with a three-stage, three-speed transmission mechanism for varying speed and torque output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a multi-stage multi-speed transmission is implemented, then speed control and torque output are improved, but device complexity increases

Engineering Contradiction:
Improvespeed control and torque outputVSAvoidtransmission system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a three-stage planetary gear transmission system where multiple gear sets are nested within a compact housing structure. Each stage of the transmission is integrated within the previous stage, allowing multiple speed ratios to be achieved in a space-efficient manner. The clutch mechanism is also nested within the transmission assembly, enabling variable speed control without requiring separate external components.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The transmission system is designed to provide multiple functions through a single integrated mechanism. The planetary gear sets enable both speed reduction and torque multiplication, while the clutch mechanism allows for variable speed control. The same transmission housing accommodates all three stages of gear reduction, making the system multi-functional and adaptable to various operating conditions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If a robust transmission system is used, then reliability is improved, but manufacturing cost increases

Engineering Contradiction:
Improvetransmission system reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines multiple transmission stages and the clutch mechanism into a single integrated assembly that is manufactured as one unit. This merging of components reduces the number of separate manufacturing processes and assembly steps, thereby lowering overall manufacturing costs while maintaining the robustness and reliability of the transmission system.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The transmission system is segmented into modular components including planetary gear sets, clutch mechanisms, and housing sections that can be manufactured separately and then assembled. This segmentation allows for standardized manufacturing processes and facilitates quality control, reducing manufacturing costs while maintaining system reliability.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP1815948B1Power tool with housing and gearbox
Publication Date: 2018.11.28 BLACK & DECKER CORP
  • EP1815948B1 patent drawingFigure 1
  • EP1815948B1 patent drawingFigure 2
  • EP1815948B1 patent drawingFigure 3

AI summary

A power tool (10) including a motor (14), an output member (20) and a transmission (16) disposed between the motor and the output member. The transmission includes a ring gear (310,360) with opposite axial end faces. The power tool also includes a clutch (18) for limiting an output of the transmission. The clutch includes an annular clutch face disposed about the ring gear. At least a portion of a side of the ring gear is configured such that an included angle between the annular clutch face and the at least a portion of the side of the ring gear is about ninety five degrees to about one hundred fifty degrees.