Multi-Drive Hammer Drill Layout With High-Ratio Compact Gearing

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Solution Overview

Problem

Existing hammer drill machines face challenges in achieving a compact design while maintaining a high reduction ratio for their gear mechanisms, often requiring additional components and increased space due to the angular arrangement of drive units and limited reduction capabilities in prior designs.

Innovation Solution

The use of a worm gear or plane spiral gear as the first gear unit, with a worm shaft or plane spiral wheel arranged coaxially with the tool receiving unit, allows for a high reduction ratio and compact design by minimizing the number of gear components and space requirements, and the second gear unit is designed as an eccentric drive to convert rotary movement into alternating linear movement for the impact mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If conventional gear units with limited reduction capability are used, then the number of components can be reduced, but the reduction ratio is insufficient and additional components are required

Engineering Contradiction:
Improvenumber of gear componentsVSAvoidreduction ratio
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent applies parameter changes by selecting worm gears and bevel gears with specific geometric parameters (helix angle, tooth profile, module) to achieve a high reduction ratio of 5:1 to 10:1 in a single stage. This changes the fundamental parameters of the gear system from conventional low-ratio gears to high-ratio worm and bevel gears, eliminating the need for multiple gear stages while maintaining compact dimensions.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If additional gear components are added to achieve higher reduction ratio, then the reduction capability is improved, but the device complexity and housing space increase

Engineering Contradiction:
Improvereduction ratioVSAvoidnumber of gear components
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges the functions of multiple gear stages into a single integrated gear unit comprising worm gears and bevel gears. The worm gear provides the primary reduction while the bevel gear adjusts the output axis orientation, combining what would traditionally require separate gear stages into one compact assembly. This merging reduces the number of components while achieving the required high reduction ratio.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If conventional gear arrangements are used, then the design is simple, but the housing space and device dimensions increase

Engineering Contradiction:
Improvedesign simplicityVSAvoidhousing space
Core Design Contradiction:
Ease of manufactureVSVolume of moving object

Solution Approach 1:

The patent utilizes three-dimensional spatial arrangement by positioning the worm gear axis perpendicular to the drive shaft axis and employing bevel gears to redirect power transmission at angled orientations. This dimensional reconfiguration allows the gear unit to fit within compact housing space while maintaining efficient power transmission, transforming a planar gear arrangement into a spatial configuration that optimizes space utilization.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 enables a compact and efficient design with a high reduction ratio, reducing housing vibrations and installation space, while allowing for precise torque transmission and variable speed control, enhancing the performance and usability of the hammer drill machine.

Implementation Method 1

The use of a worm gear or plane spiral gear as the first gear unit, with a worm shaft or plane spiral wheel arranged coaxially with the tool receiving unit, allows for a high reduction ratio and compact design

Methodology Applied
Scientific EffectWorm gear mechanism: Worm Drive

Implementation Method 2

The use of a worm gear or plane spiral gear as the first gear unit, with a worm shaft or plane spiral wheel arranged coaxially with the tool receiving unit

Methodology Applied
Scientific EffectSpiral gear mechanism: Gear

Implementation Method 3

the second gear unit is designed as an eccentric drive to convert rotary movement into alternating linear movement for the impact mechanism

Methodology Applied
Scientific EffectEccentric mechanism: Eccentric

Data Source

PatentEP4438232A1Multi-drive hammer drill machine
Publication Date: 2024.10.02 HILTI AG
  • EP4438232A1 patent drawingFigure 1~2
  • EP4438232A1 patent drawingFigure 3~5
  • EP4438232A1 patent drawingFigure 6~8b

AI summary

The invention relates to a rotary hammer machine with a handheld machine housing (1) for housing electric drive means, comprising a first electromechanical drive unit (4) configured to drive a tool holder unit (3) for a drill bit (2) with a rotary movement, a second electromechanical drive unit (5) configured to drive a percussion unit (6) to generate an alternating linear movement for an additional rearward impact on the drill bit (2), wherein the axes of rotation (AM1, AM2) of the two electromechanical drive units (4, 5) are adjacent to each other and transverse to the percussion axis (As), for which a first gear unit (7;7') is provided for the angled reduction of a rotary motion of the first electromechanical drive unit (4) for the drive of the tool holding unit (3), and a second gear unit (8) is provided for converting the rotary motion of the second electromechanical drive unit (5) into the alternating linear motion for the drive of the impact unit (6).