Chainsaw Safety Switch Assembly for Intentional Drive Activation

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Solution Overview

Problem

Existing chain saws lack effective mechanisms to prevent unintentional activation of the drive unit, leading to potential safety hazards and injuries, especially in electric models where operational readiness is not indicated by engine noise.

Innovation Solution

A safety switching arrangement with first and second enabling elements, assigned to the main and auxiliary handles respectively, which require specific activation sequences and time periods to ensure safe and intentional activation of the drive unit, including a display device for visual, tactile, and acoustic feedback to confirm activation status.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a simple activation mechanism is used for the drive unit, then ease of operation is improved, but safety is worsened due to risk of unintentional activation

Engineering Contradiction:
Improveease of activationVSAvoidsafety against unintentional activation
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The activation process is divided into two distinct release elements: a first release element (e.g., trigger or button) and a second release element (e.g., safety switch or lever). Both elements must be activated in sequence to enable the drive unit, preventing accidental activation while maintaining operational simplicity. This segmentation of the activation mechanism directly addresses the contradiction by requiring deliberate sequential actions.

Inventive Principle:
Principle #1Segmentation

2Reliability

If multiple release elements are required for activation, then safety is improved, but device complexity increases

Engineering Contradiction:
Improvesafety against unintentional activationVSAvoidcomplexity of activation mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The first and second release elements are integrated into the existing handle structure of the chainsaw. The first release element is typically combined with the trigger mechanism, and the second release element is integrated into the auxiliary handle or guard structure. This merging approach minimizes additional components while achieving the safety function through clever integration of release elements into familiar structural elements.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If no activation confirmation is provided, then device complexity is reduced, but safety is worsened due to lack of feedback on activation status

Engineering Contradiction:
Improveconfirmation of activation statusVSAvoidcomplexity of feedback system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A visual indicator (such as an LED or display element) is incorporated into the chainsaw to provide real-time feedback on the activation status. The indicator shows whether the drive unit is ready to operate or if the safety switching arrangement is active, giving the user clear confirmation of the current state. This feedback mechanism enhances safety by eliminating ambiguity about activation status without adding significant complexity.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3595854B1Chainsaw
Publication Date: 2022.08.03 ROBERT BOSCH GMBH
  • EP3595854B1 patent drawingFigure 1~2
  • EP3595854B1 patent drawingFigure 3
  • EP3595854B1 patent drawingFigure 4

AI summary

The invention relates to a chainsaw (100) with a housing (110) in which a drive unit (140) for driving a saw chain (144) is arranged. A main handle (112) and an auxiliary handle (115) are arranged on the housing (110). The main handle (112) is paired with an operating element (160) for activating the drive unit (140), and the auxiliary handle (115) is paired with a hand guard (117) for activating a brake device (180). A safety switch assembly (120) is provided for activating and/or deactivating the drive unit (140), said safety switch assembly being paired with a first and a second release element (122, 124). The first release element (122) can be activated in order to carry out a first release function in order to initiate the activation of the safety switch assembly (120), and the second release element (124) can be activated in order to carry out a second release function in order to allow the drive unit (140) to be activated via the operating element (160).