Hand Tool Attachment Clutch for Safe Cutting Transition

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Solution Overview

Problem

Handheld power tools lack a reliable and safe mechanism to transition from drilling or screwing functions to cutting functions for gardening tasks, such as cutting grass or hedges, without risking accidental operation of cutting elements.

Innovation Solution

A locking unit with a clutch system that allows for torque transmission from the power tool's drive unit to a cutting unit, featuring a manually switchable clutch for safe operation, an eccentric mechanism for linear movement of cutting elements, and a compact design that eliminates the need for additional angular gears, enabling ergonomic operation with reduced risk of accidental contact with cutting elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a locking unit with clutch system is added to enable cutting function, then the versatility of the power tool is improved, but the device complexity increases

Engineering Contradiction:
Improvefunctionality transition from drilling/screwing to cuttingVSAvoidlocking unit with clutch system
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The attachment enables the power tool to perform multiple functions by integrating a cutting unit that can be coupled to the drive shaft. The locking unit with clutch system allows the same tool to switch between drilling/screwing operations and cutting operations, making the tool versatile for both construction and gardening applications.

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

Solution Approach 2:

The cutting attachment is designed as a separate module that can be attached to or removed from the power tool. The locking unit with clutch mechanism is integrated into this modular attachment, allowing independent operation and easy separation from the main tool body.

Inventive Principle:
Principle #1Segmentation

2Reliability

If a manually switchable clutch is implemented for safe operation, then the safety is improved, but the ease of operation deteriorates

Engineering Contradiction:
Improvesafety mechanism preventing accidental operationVSAvoidmanual switching requirement
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The clutch mechanism is pre-configured in a disengaged state, requiring intentional manual activation before the cutting unit can operate. This preliminary action ensures that the cutting function is only activated when the user deliberately intends to use it, preventing accidental operation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The clutch acts as an intermediary between the drive shaft and the cutting unit. It mediates the power transmission by requiring manual engagement, serving as a safety barrier that prevents direct activation of the cutting elements unless intentionally triggered.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If an eccentric mechanism is used for linear movement of cutting elements, then the manufacturing precision is improved, but the device complexity increases

Engineering Contradiction:
Improvelinear movement conversion from rotational motionVSAvoidgearbox with eccentric mechanism
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The eccentric mechanism utilizes an off-center rotational path to convert the rotational motion from the drive shaft into linear reciprocating motion of the cutting elements. This curved motion path provides precise control over the cutting elements' movement without requiring complex mechanical linkages.

Inventive Principle:
Principle #14Spheroidality (Curvature)

4Ease of operation

If the cutting elements are arranged at least partially outside the housing, then the ease of operation is improved, but the object-generated harmful factors increase

Engineering Contradiction:
Improveaccessibility of cutting elementsVSAvoidrisk of accidental contact with cutting elements
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The cutting elements are positioned outside the housing in a dynamic configuration where they can move between an operational position and a retracted or protected position. This dynamic arrangement allows easy access during operation while reducing exposure risk when the cutting function is not actively engaged.

Inventive Principle:
Principle #15Dynamics

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

Enables safe and efficient transition from drilling or screwing to cutting functions, enhancing the versatility of handheld power tools while minimizing the risk of accidental contact with cutting elements, and providing ergonomic benefits through a compact and intuitive design.

Implementation Method 1

a first clutch half (152) which is connected to the drive shaft (122) and a second clutch half (154) which is connected to the drive element (186)

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

The cutting unit preferably includes an eccentric unit which is configured to translate the rotational movement of an output shaft of the attachment into a substantially linear movement of at least one cutting element

Methodology Applied
Scientific EffectEccentric mechanism: Eccentric

Data Source

PatentEP3178613B1Attachment for a hand tool
Publication Date: 2019.01.23 ROBERT BOSCH GMBH
  • EP3178613B1 patent drawingFigure 1
  • EP3178613B1 patent drawingFigure 2
  • EP3178613B1 patent drawingFigure 3

AI summary

The invention relates to an attachment for a hand-held power tool with a cutting unit, intended for gardening tasks. The attachment is connected to the power tool via a locking unit and includes a gearbox with a clutch. The clutch can be engaged via an actuating unit.