String Trimmer Head Wear Ring Structure for Housing Protection

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Solution Overview

Problem

Conventional string trimmers suffer from wear and damage to the housing when bumped against surfaces due to the angle at which the trimmer head is oriented, leading to potential damage to the sidewall and base wall.

Innovation Solution

Incorporation of wear rings and chamfered edges on the trimmer head design that protrude from the base wall and sidewall, respectively, to prevent direct contact with the work surface, thereby protecting the housing from wear and damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the trimmer head housing directly contacts the work surface during operation, then the housing structure is simple, but the housing suffers from wear and damage reducing reliability

Engineering Contradiction:

Improvehousing durabilityVSAvoidhousing structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces wear rings as intermediary elements between the housing and the work surface. These wear rings contact the ground first, protecting the main housing from direct contact and wear. The wear rings act as sacrificial components that can be replaced without replacing the entire housing assembly.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The housing is segmented into protective wear rings and the main housing body. The wear rings are separate replaceable components that can be independently maintained, allowing the main housing to remain durable while the wear rings absorb the wear from surface contact.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the trimmer head is oriented at various angles during operation, then the trimmer can adapt to different working positions, but the housing is more susceptible to damage from angled impacts

Engineering Contradiction:

Improveworking position flexibilityVSAvoidimpact damage risk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The chamfered edges are pre-configured on the housing to provide protective geometry before impact occurs. The angled surfaces are designed to deflect impact forces away from critical housing areas, reducing damage from angled contacts that occur during versatile positioning.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The chamfered edges create asymmetric geometry on the otherwise cylindrical housing. This asymmetric feature provides directional protection for angled impacts while maintaining the overall symmetric cylindrical shape for versatile positioning capabilities.

Inventive Principle:

Principle #4Asymmetry

3Reliability

If wear rings and chamfered edges are added to protect the housing, then the housing is protected from wear, but the device complexity increases

Engineering Contradiction:

Improvehousing protectionVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The wear rings are designed as inexpensive, replaceable components that absorb wear instead of the expensive main housing. These sacrificial wear rings can be easily replaced when worn, protecting the investment in the main housing while keeping maintenance costs low.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS20260013426A1String trimmer head

Publication Date: 2026.01.15 MILWAUKEE ELECTRIC TOOL CORP

AI summary

A trimmer head includes a housing rotatable about a rotational axis. The housing includes a main body defining a cavity, and a cap removably coupled to the main body. The trimmer head additionally includes a spool supported in the cavity and operable to support line to be dispensed, a retainer positioned between the housing and the spool. and a first ring protruding from a distal end of the housing.