Pivotable Support Bracket for Hand-Held Blower Recoil

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Solution Overview

Problem

Existing hand-held work tools, such as blowers, often require significant effort to operate due to the weight and recoil forces, leading to operator fatigue, especially when used for extended periods or with high blowing capacity.

Innovation Solution

A support device with a connecting mechanism that pivots about a vertical axis, allowing the tool to be positioned with its center of gravity aligned with the operator's body, thereby reducing the tilting moment and recoil force absorption by the operator, and incorporating a detachable design for flexibility and ergonomic use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the blowing capacity is increased to improve productivity, then the blowing performance is improved, but the recoil force and weight increase causing operator fatigue

Engineering Contradiction:
Improveblowing capacityVSAvoidoperator fatigue
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent introduces a support device as an intermediary between the blower and the operator. This support device includes a mounting plate with a first mounting point positioned laterally offset from the blower's center of gravity, and a connecting device that transfers both the weight force and the tilting moment generated by high-capacity blowers to the operator's body, thereby mediating the harmful effects of increased blowing capacity on operator comfort

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the tool is positioned closer to the operator's body to reduce tilting moment, then ease of operation is improved, but the tool may come into lateral contact with the operator restricting movement

Engineering Contradiction:
Improvetilting moment reductionVSAvoidtool movement freedom
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent resolves this contradiction by moving the first mounting point not just closer to the operator's body, but specifically to a lateral offset position in a different spatial dimension. The mounting plate is positioned laterally offset from the center of gravity by a distance that creates an optimal balance: close enough to minimize the tilting moment while maintaining sufficient clearance to prevent contact with the operator's body, thus preserving tool movement freedom

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

3Stability of the object's composition

If a rigid connection is used to fully support the tool weight, then stability is improved, but the operator cannot absorb recoil forces effectively

Engineering Contradiction:
Improvetool support stabilityVSAvoidrecoil force absorption
Core Design Contradiction:
Stability of the object's compositionVSForce

Solution Approach 1:

The patent applies dynamics by making the connecting device pivotable about a pivot axis. This dynamic connection allows the tool to rotate freely in response to recoil forces and operator movements, preventing the buildup of destabilizing moments while still transferring the weight force and controlling tilting motion. The pivotable connection adapts to varying force conditions rather than rigidly resisting them

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3677386B1Assembly with a hand-held tool and with a support device and hand-held tool
Publication Date: 2021.11.24 ANDREAS STIHL AG & CO KG
  • EP3677386B1 patent drawingFigure 1~3
  • EP3677386B1 patent drawingFigure 4~6
  • EP3677386B1 patent drawingFigure 7~9

AI summary

An arrangement is provided with a hand-held work device and a support device (20). The work device has a housing (2) on which at least one handle (3) for guiding the work device during operation is arranged. The support device (20) has a bracket (21) to be carried by an operator (19). The support device (20) comprises a connecting device (9) which is held at a first attachment point (30) of the bracket (21) and at a second attachment point (31) on the work device. The connecting device (9) is pivotably mounted at the second attachment point (31) about at least one pivot axis (27). The connecting device supports the work device in the working position (10) relative to the operator (19) to the rear and prevents the work device from moving backward.The center of gravity (17) of the work tool and the first attachment point (30) are at a distance (a) from each other in the horizontal direction and in the lateral direction relative to the operator (19) when the work tool is in its working position (10). The support (21) has means at the first attachment point (30) for at least partially supporting the tipping moment that the weight force (F) of the work tool exerts at the first attachment point (30) due to the lateral distance (a).