Telescopic Handle Locking for Lawn Mower Stability

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Solution Overview

Problem

Hand-held soil cultivation devices, such as lawn mowers, face challenges in providing a secure and adjustable handle system that prevents unintentional pivoting and allows for easy operation and storage, while ensuring user safety and comfort.

Innovation Solution

A telescopic guide rod system with a pivoting unit and a safety device that locks the handle in place, featuring a spring-loaded securing element and an unlocking mechanism, allows for adjustable height and secure operation, and a fixing unit with opposing elements for smooth operation and cost-effective construction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the guide device is made pivotable for space-saving storage, then storage convenience is improved, but unintentional pivoting may occur during operation

Engineering Contradiction:
Improvestorage convenienceVSAvoidoperational stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The guide device employs a dynamic locking system where the securing element can transition between locked and unlocked states. During operation, the securing element engages with the housing bearing element to prevent pivoting. During storage, the securing element can be disengaged to allow the guide device to pivot parallel to the housing, enabling space-saving storage while preventing unintentional movement during use.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the degree of freedom parameter of the pivoting unit. In the unactuated state, one rotational degree of freedom is blocked by the securing element. In the actuated state, the securing element releases, allowing at least one rotational degree of freedom. This parameter change enables the guide device to be locked during operation and unlocked for storage positioning.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a securing device is added to prevent unintentional pivoting, then operational stability is improved, but device complexity increases

Engineering Contradiction:
Improveoperational stabilityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The securing device is merged with the existing pivoting unit structure. The securing element is integrated into the guide device assembly, and the unlocking element is formed by the fixing housing. This merging approach allows the securing function to be added without significantly increasing overall device complexity, as components serve multiple functions within the same structural framework.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The securing element is designed to be automatically actuated by the relative movement of the guide members during normal operation. When the first guide member moves telescopically, it automatically engages or disengages the securing element, eliminating the need for separate manual locking mechanisms and reducing operational complexity.

Inventive Principle:
Principle #25Self-service

3Reliability

If the guide device is locked during operation, then operational stability is improved, but ease of adjustment for storage is reduced

Engineering Contradiction:
Improveoperational stabilityVSAvoidadjustment ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The securing device is designed to be automatically actuated by the relative movement of the guide members during normal operation. When the first guide member moves telescopically, it automatically engages or disengages the securing element, eliminating the need for separate manual locking mechanisms and reducing operational complexity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The securing element is positioned and pre-loaded by spring elements before operation begins. This preliminary positioning ensures that the securing element is ready to engage immediately when the guide device is assembled, providing instant operational stability without requiring additional adjustment steps during use.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If spring elements are used to hold the securing device, then operational stability is improved, but manufacturing cost increases

Engineering Contradiction:
Improvesecuring reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The spring elements used in the securing device are standard, off-the-shelf components that are inexpensive to manufacture and replace. These simple mechanical spring elements provide reliable securing force without requiring complex manufacturing processes, keeping production costs low while maintaining operational stability.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 system ensures secure handling, prevents unintentional pivoting, and allows for easy adjustment and storage, enhancing user safety and comfort while maintaining a cost-effective design.

Implementation Method 1

The securing element is subjected to a force in particular by a spring element

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP3381261B1Soil cultivation device
Publication Date: 2024.10.23 ROBERT BOSCH GMBH
  • EP3381261B1 patent drawingFigure 1a
  • EP3381261B1 patent drawingFigure 1b
  • EP3381261B1 patent drawingFigure 2a~2b

AI summary

The invention relates to a hand-held soil cultivation implement (10), in particular a lawn mower, comprising a housing (12) and a guide device (20), wherein the guide device (20) has two telescopically guided guide members (22, 24), the first guide member (22) having a handle (26) comprising a switching unit (28) and the second guide member (24) being connected to the housing (12). It is proposed that movement of the first guide member (22) against a telescopic direction (60) is limited by a limiting element (118), which is attached to the first guide member (22) via at least a first attachment area (120) and to the second guide member (24) and/or to the housing (12) via at least a second attachment area (122).