Eccentric Washer Handle Adjustment for Rough Terrain

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Solution Overview

Problem

Existing height-adjustable lawnmower handles are prone to losing grip and changing position when the mower falls into a hole, making it difficult and dangerous to mow rough terrain, as they rely on mechanisms like return springs or rotating tips that can inadvertently disengage.

Innovation Solution

A height-adjustable lawnmower handle with a connection bracket system using an eccentric washer and catch mechanism, allowing the handle to securely adjust height without relying on weak parts like return springs, ensuring stability and grip on rough terrain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a return spring mechanism is used to allow height adjustment, then the handle can be easily adjusted to different positions, but the handle may inadvertently disengage when the lawnmower falls into a hole on rough terrain

Engineering Contradiction:
Improvehandle height adjustmentVSAvoidhandle grip stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The bond pin is preliminarily positioned in one of multiple housings before operation. The user selectively places the bond pin in a desired housing to pre-set the handle height, eliminating the need for return springs or complex adjustment mechanisms during operation. This preliminary positioning ensures reliable grip while maintaining ease of adjustment.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The connection bracket is segmented into multiple discrete housings (e.g., four housings) arranged at different positions. The bond pin can be placed in any one of these segmented housings to achieve different handle heights. This segmentation provides both adjustment capability and secure positioning, as the bond pin remains firmly engaged in the selected housing.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If a circular element with saw tooth circumference is used for height adjustment, then the handle can rotate to different positions, but the handle may inadvertently rotate and disengage when the lawnmower falls into a hole

Engineering Contradiction:
Improvehandle position variabilityVSAvoidengaging tip retention
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

Instead of relying on rotational movement that can be inadvertently triggered, the engaging tip (bond pin) is preliminarily placed in one of multiple fixed housings. This eliminates the rotational mechanism entirely and provides reliable retention, as the bond pin simply rests in the selected housing without any moving parts that could inadvertently disengage.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If multiple L-shaped elements with a return spring are used for height adjustment, then the bond pin can be maintained in different housings, but the curvilinear lower portion of the through hole allows the bond pin to slide inadvertently when the spring is in working position

Engineering Contradiction:
Improvebond pin positioningVSAvoidbond pin housing retention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The return spring mechanism is completely extracted from the design. The bond pin is simply placed in one of multiple housings without any spring to push it along a curvilinear path. This eliminates the harmful sliding motion that could inadvertently disengage the bond pin while maintaining easy positioning by selective placement.

Inventive Principle:
Principle #2Taking out (Extraction)

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 handle remains securely attached to the mower, preventing accidental disengagement and ensuring safe, optimal lawn mowing across various terrains without the risk of losing control.

Implementation Method 1

said bond pin (42) being rotatable about a second axis (R) transversal to the longitudinal axis (M) of said handle (1) by means of an eccentric washer (4)

Methodology Applied
Scientific EffectEccentric rotation: Eccentric

Data Source

PatentEP3099155B1Height-adjustable lawnmower handle
Publication Date: 2019.04.03 STIGA S P A IN BREVE ANCHE ST SPA
  • EP3099155B1 patent drawingFigure 1~2
  • EP3099155B1 patent drawingFigure 3~4
  • EP3099155B1 patent drawingFigure 5~6

AI summary

A handle (1) of a lawnmower (10) is described, comprising two lower ends (12) pivoted with a body (101) of the lawnmower (10), being suitable for passing from at least one high position to at least one low position, being rotatably connected to the body (101) by means of a fulcrum pin (31) to rotate the handle (1) and a bond pin (42), suitable for pivoting in an eccentric washer (4) comprising recesses (45, 47) suitable for engaging with at least one catch (23) to block the eccentric washer (4) in at least two positions of engagement corresponding to the high position and the low position of the handle (1), respectively, said eccentric washer (4) passes from a first to a second position of engagement by translating and rotating about an axis (R).