Hand-Held Rotary Impact Mechanism With Integrated Ring-Gear Cover

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Solution Overview

Problem

Existing hand-held power tools, particularly rotary impact wrenches, face challenges in achieving a compact design with a short overall length and a low number of components while maintaining efficient operation and reliable sealing of the rotary impact mechanism.

Innovation Solution

The integration of the impact mechanism cover with the ring gear, combined with an intermediate shaft mounted within the impact mechanism cover and supported by a bearing, allows for a compact design with a low tolerance chain and efficient sealing, using a planetary gear system and rolling bearings for reduced friction and enhanced support.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the impact mechanism cover and ring gear are formed as separate components, then assembly flexibility and manufacturing ease are improved, but the overall length and component count increase

Engineering Contradiction:
Improveassembly flexibilityVSAvoidoverall length
Core Design Contradiction:
Ease of manufactureVSLength of moving object

Solution Approach 1:

The impact mechanism cover and ring gear are merged into a single integrated component. The ring gear is formed with an integrally formed cover portion that extends to close off the rotary impact mechanism, eliminating the need for a separate cover component. This integration directly reduces the overall length of the power tool device while maintaining structural integrity and functional performance.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If more components are used to support the intermediate shaft, then reliability and support stability are improved, but device complexity and component count increase

Engineering Contradiction:
Improvesupport stabilityVSAvoidcomponent count
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The bearing support structure is integrated into the impact mechanism cover. The cover includes a bearing receptacle formed as part of the integrated component, which receives and supports the intermediate shaft bearing. This integration reduces the number of separate support components while maintaining reliable shaft support through the unified structural design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The impact mechanism cover serves multiple functions: it closes off the rotary impact mechanism, provides structural support, contains the bearing receptacle for intermediate shaft support, and integrates with the ring gear. This multi-functionality reduces the need for separate dedicated components for each function, thereby reducing overall device complexity.

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

3Length of moving object

If the impact mechanism cover is integrated with the ring gear, then overall length and component count are reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improveoverall lengthVSAvoidintegration precision
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

The ring gear and impact mechanism cover are formed as a single integrated component, either through integral forming processes or precision joining methods. The integration requires precise manufacturing to ensure proper alignment of the gear teeth, bearing receptacle positioning, and overall structural integrity, but modern manufacturing capabilities can achieve these precision requirements.

Inventive Principle:
Principle #5Merging (Combining)

4Length of moving object

If intermediate shaft is mounted within the impact mechanism cover, then compact design is achieved, but sealing requirements become more stringent

Engineering Contradiction:
Improvecompact designVSAvoidsealing reliability
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The intermediate shaft is nested within the impact mechanism cover, with the shaft positioned inside the cover's internal space. The cover includes a bearing receptacle that houses the intermediate shaft bearing, creating a nested arrangement that maximizes compactness. This nesting requires effective sealing between the shaft and cover to prevent contamination and maintain reliability in the compact configuration.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 configuration achieves a significantly shorter overall length, reduced component count, and improved reliability through enhanced sealing and support, resulting in a more compact and efficient rotary impact wrench.

Implementation Method 1

an intermediate shaft bearing (48) for supporting the intermediate shaft (18), which is arranged at least partially within an impact mechanism cover (44) of the rotary impact mechanism

Methodology Applied
Scientific EffectRolling bearing: Ball Bearing

Implementation Method 2

using a planetary gear system and rolling bearings for reduced friction and enhanced support

Methodology Applied
Scientific EffectFriction reduction: Friction

Data Source

PatentEP3481590B1Hand-held power tool device
Publication Date: 2025.10.15 ROBERT BOSCH GMBH
  • EP3481590B1 patent drawingFigure 1
  • EP3481590B1 patent drawingFigure 2
  • EP3481590B1 patent drawingFigure 3

AI summary

The invention relates to a hand-held power tool device, comprising at least one rotary percussion mechanism (16a; 16b; 16c). The at least one rotary percussion mechanism has at least one planetary gearing (50a; 50b; 50c) having at least one ring gear (46a; 46b; 46c), at least one percussion-mechanism cover (44a; 44b; 44c), and at least one intermediate shaft (18a; 18b; 18c). The intermediate shaft (18a; 18b; 18c) is mounted at least partially within the percussion-mechanism cover (44a; 44b; 44c). According to the invention, the percussion-mechanism cover (44a; 44b; 44c) is integral with the ring gear (46a; 46b; 46c).