Ring Gear Fixing Element for Handheld Power Tool Stability

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Solution Overview

Problem

Existing handheld power tool devices with rotary impact mechanisms face challenges in achieving a compact design and secure mechanical connections between the ring gear and hammer mechanism housing, leading to inefficiencies in energy transmission and stability.

Innovation Solution

Incorporating a ring gear fixing element that forms a mechanically stable connection with the hammer mechanism housing, either through a one-piece design or a thread-based screw connection, allowing for secure fixation and reduced tolerance chain length, thereby enhancing the tool's compactness and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a traditional multi-component connection method is used for the ring gear and hammer mechanism housing, then the mechanical connection can be achieved, but the device complexity increases and the overall length increases

Engineering Contradiction:
Improvemechanical connection structureVSAvoidoverall length
Core Design Contradiction:
Device complexityVSLength of stationary object

Solution Approach 1:

The patent combines the ring gear and hammer mechanism housing into a single integrated component. The ring gear is formed as one piece with the hammer mechanism housing, eliminating the need for separate connection elements such as screws, keys, or other fastening components. This merging reduces device complexity by removing multiple parts and simplifies the mechanical connection structure while also reducing the overall length of the tool by eliminating gaps and connection interfaces between separate components.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If a traditional multi-component connection method is used for the ring gear and hammer mechanism housing, then the mechanical connection can be achieved, but the tolerance chain length increases leading to reduced manufacturing precision

Engineering Contradiction:
Improvetolerance chain lengthVSAvoidmechanical connection structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

By forming the ring gear and hammer mechanism housing as a single integrated component through processes such as injection molding or die casting, the patent eliminates the tolerance chain that would exist between multiple assembled parts. The single-piece construction ensures precise geometric relationships between the ring gear teeth and the hammer mechanism components without accumulation of manufacturing tolerances, thereby improving manufacturing precision while reducing device complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If a secure mechanical connection is achieved through multiple connection elements, then the reliability of the connection is improved, but the device complexity and overall length increase

Engineering Contradiction:
Improveconnection stabilityVSAvoidmechanical connection structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The integrated design of the ring gear and hammer mechanism housing as a single component ensures inherent connection stability without requiring additional connection elements. The monolithic construction eliminates potential failure points associated with separate fasteners, keys, or interference fits, while the precise geometric integration during manufacturing ensures reliable force transmission between the ring gear and hammer mechanism, thereby maintaining high reliability with reduced device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3332918B1Handheld machine tool
Publication Date: 2021.01.06 ROBERT BOSCH GMBH
  • EP3332918B1 patent drawingFigure 1
  • EP3332918B1 patent drawingFigure 2
  • EP3332918B1 patent drawingFigure 3

AI summary

The invention relates to a hand-held power tool device comprising at least one drive housing (12), at least one impact mechanism housing (14), and at least one rotary impact mechanism (16), which includes at least one planetary gear (18) with at least one ring gear (20). It is proposed that the ring gear (20) includes at least one ring gear fixing element (22) for fixing the ring gear (20) to the impact mechanism housing (14).