Dual-Eccentric Oscillating Drive for Low-Noise Power Tools

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Solution Overview

Problem

Existing oscillating drive devices for hand-held power tools face challenges in achieving reliable and efficient power transmission with low load on components, minimizing noise, and avoiding twisting, while maintaining a compact design.

Innovation Solution

The oscillating drive device employs two eccentric elements arranged on opposite sides of an imaginary plane with an angular offset, spaced apart along the input shaft, and a movement converter to transmit power symmetrically to the output shaft, with a balancing mass for vibration compensation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single eccentric element is used for oscillating drive, then the device structure is simple, but the load on components is high and noise increases

Engineering Contradiction:
Improvestructure simplicityVSAvoidcomponent load
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The single eccentric element is divided into two separate eccentric elements (first eccentric element and second eccentric element) that are arranged on opposite sides of the input shaft. This segmentation distributes the power transmission load across multiple elements, reducing the stress on each individual component while maintaining the oscillating drive function.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If a single eccentric element is used for oscillating drive, then the device structure is simple, but noise development increases

Engineering Contradiction:
Improvestructure simplicityVSAvoidnoise
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

By segmenting the power transmission into two eccentric elements, the mechanical stress and resulting noise from a single overloaded element is distributed. The opposing arrangement of the two eccentric elements creates balanced force transmission that reduces vibration and noise generation.

Inventive Principle:
Principle #1Segmentation

3Ease of operation

If power is transmitted through a single eccentric element, then the transmission path is short, but twisting occurs

Engineering Contradiction:
Improvepower transmission efficiencyVSAvoidtwisting
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The two eccentric elements are positioned asymmetrically on opposite sides of the input shaft, with each element having its own specific eccentricity vector. This asymmetric arrangement creates opposing force components that cancel out twisting moments while maintaining efficient power transmission to the output shaft.

Inventive Principle:
Principle #4Asymmetry

4Reliability

If two eccentric elements are arranged on opposite sides with angular offset, then load distribution is improved, but device complexity increases

Engineering Contradiction:
Improveload distributionVSAvoidarrangement complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The two eccentric elements are merged into a single integrated transmission unit that operates as a cohesive system. The movement converter combines the motion from both eccentric elements into a unified oscillating output, managing the complexity through functional integration rather than separate independent mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

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 ensures reliable power transmission with low component load, reduced noise, and efficient power distribution, while maintaining a compact design and minimizing vibrations, enhancing user experience and machining precision.

Implementation Method 1

which comprises at least one eccentric element for oscillating drive of the output shaft, the transmission unit comprising at least two eccentric elements for an oscillating drive of the output shaft

Methodology Applied
Scientific EffectEccentric mechanism: Eccentric

Implementation Method 2

with a balancing mass for vibration compensation

Methodology Applied
Scientific EffectVibration compensation: Tuned Mass Damper

Data Source

PatentEP3164252B1Oscillatory driving device
Publication Date: 2021.09.01 ROBERT BOSCH GMBH
  • EP3164252B1 patent drawingFigure 1
  • EP3164252B1 patent drawingFigure 2~3
  • EP3164252B1 patent drawingFigure 4~5

AI summary

The invention relates to an oscillatory driving device for a hand-held power tool (12a; 12b; 12c; 12d; 12e; 12f; 12g), comprising at least one input shaft (14a; 14b; 14c; 14d; 14e; 14f; 14g), at least one output shaft (16a; 16b; 16c; 16d; 16e; 16f; 16g), and at least one gearing unit (18a; 18b; 18c; 18d; 18e; 18f; 18g), which operatively connects the input shaft (14a; 14b; 14c; 14d; 14e; 14f; 14g) to the output shaft (16a; 16b; 16c; 16d; 16e; 16f; 16g) and which comprises at least one eccentric element (20a; 20b; 20c; 20d; 20e; 20f; 20g) for driving the output shaft (16a; 16b; 16c; 16d; 16e; 16f; 16g) in an oscillatory manner. According to the invention, the gearing unit (18a; 18b; 18c; 18d; 18e; 18f; 18g) comprises at least one further eccentric element (22a; 22b; 22c; 22d; 22e; 22f; 22g) for driving the output shaft (16a; 16b; 16c; 16d; 16e; 16f; 16g) in an oscillatory manner.