Portable Machine Tool Angular Transmission Design

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Solution Overview

Problem

Conventional machine tools lack a compact and versatile design for portable applications, with existing systems being bulky and inefficient in transmitting drive torque, which limits their portability and operational convenience.

Innovation Solution

A machine tool system featuring a multi-stage angular transmission unit with a motor unit and a guide unit forming a closed system, where the output shaft is arranged at 90° relative to the motor unit's longitudinal axis, and a gear unit providing a large transmission ratio, allowing for a compact and versatile design with a laterally offset coupling device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a conventional machine tool design is used, then the structure is simple, but the size is bulky and portability is poor

Engineering Contradiction:
Improvemachine tool sizeVSAvoidportability
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The guide unit is integrated into the housing structure, with the cutting strand nested within the guide unit's circumferential path. The transmission unit is positioned within the housing to surround the motor unit's longitudinal axis, creating a compact nested arrangement that reduces overall machine tool volume while maintaining functional integrity

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The transmission unit is arranged in a multi-stage angular configuration where the output shaft's output axis is positioned at 90° to the motor unit's longitudinal axis. This spatial reorientation allows the drive torque to be transmitted efficiently while reducing the machine tool's footprint in the longitudinal direction, improving portability

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

2Power

If a multi-stage angular transmission is used, then torque transmission is enhanced, but the device complexity increases

Engineering Contradiction:
Improvedrive torque transmissionVSAvoidtransmission unit complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The transmission unit serves multiple functions: it transmits drive torque from the motor unit to the guide unit, positions the output shaft at 90° to the motor axis for compact arrangement, and provides structural support within the housing. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity despite the multi-stage angular configuration

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

Solution Approach 2:

The transmission unit is merged with the housing structure, where the housing provides both structural support and mounting for the transmission components. The transmission unit surrounds the motor unit's longitudinal axis, combining the motor mounting and torque transmission functions into a single integrated arrangement

Inventive Principle:
Principle #5Merging (Combining)

3Volume of moving object

If the output shaft is arranged at 90° to the motor unit axis, then the machine tool becomes more compact, but the transmission unit complexity increases

Engineering Contradiction:
Improvemachine tool volumeVSAvoidtransmission unit structure
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The output shaft is positioned at 90° to the motor unit's longitudinal axis, transferring the drive torque from the motor's longitudinal direction to a transverse direction. This dimensional change allows the guide unit and cutting strand to be arranged compactly around the motor unit, significantly reducing the machine tool's overall volume while the transmission unit's angular stages handle the complexity

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

4Power

If a large transmission ratio is used, then the drive torque is increased, but the gear unit size increases

Engineering Contradiction:
Improvedrive torqueVSAvoidgear unit volume
Core Design Contradiction:
PowerVSVolume of moving object

Solution Approach 1:

The gear unit is positioned within the housing to surround the motor unit's longitudinal axis, with the transmission unit nested in the space between the motor unit and the housing's outer surface. This nested arrangement allows the gear unit to achieve a large transmission ratio for increased drive torque while maintaining a compact overall volume by utilizing the available radial space efficiently

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

The solution enables a compact, portable machine tool with enhanced operational convenience and torque transmission, allowing for efficient machining with reduced tool size and improved handling.

Implementation Method 1

at least one motor unit (22a, 22b) for driving the machine tool parting device (18a, 18b)

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

The transmission unit is designed as a multi-stage angular transmission that includes at least one output shaft (24a, 24b), which has an output axis (28a, 28b) that is arranged at 90° relative to a longitudinal axis (26a, 26b) of the motor unit (22a, 22b)

Methodology Applied
Scientific EffectGear transmission: Gear

Implementation Method 3

a machine tool parting device comprising a cutting strand (14a, 14b) and at least one guide unit (16a, 16b)... intended to locally break the atomic cohesion of a workpiece to be machined to be machined, in particular by means of a mechanical separation

Methodology Applied
Scientific EffectMechanical separation: Fracture Mechanics

Data Source

PatentEP2890524B1Machine tool system
Publication Date: 2017.04.26 ROBERT BOSCH GMBH
  • EP2890524B1 patent drawingFigure 1~2
  • EP2890524B1 patent drawingFigure 3~4

AI summary

The invention relates to a machine tool, in particular a portable machine tool, having at least one coupling device (12a; 12b) for the coupling of a machine-tool parting device (18a; 18b) which comprises at least one cutting strand (14a; 14b) and at least one guide unit (16a; 16b), having at least one gearing unit (20a; 20b) and having at least one motor unit (22a; 22b) for driving the machine-tool parting device (18a; 18b) when the latter is arranged on the coupling device (12a; 12b). It is proposed that the gearing unit (20a; 20b) be in the form of a multi-stage angular gear which comprises at least one drive output shaft (24a; 24b) which has a drive output axis (28a; 28b) arranged at 90° relative to a motor unit longitudinal axis (26a; 26b) of the motor unit (22a; 22b).