Portable Chain Saw Layout for Ergonomic Weight Balance

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Solution Overview

Problem

Existing hand-held cutting devices lack ergonomic design, leading to user fatigue during long-term use, as they do not effectively distribute the weight and balance of the device, causing discomfort and strain.

Innovation Solution

The cutting device is designed with a central housing section that radially extends the handle, motor housing, and cutting attachment, forming ergonomic angles and a protected receptacle for the user's hand, allowing for balanced grip and reduced fatigue, with the handle and motor housing forming a hand angle of 40° to 80° and a grip angle greater than 90°, enhancing user comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the cutting device uses a conventional layout with the motor, handle, and cutting attachment arranged in a traditional configuration, then the device structure is simple, but the user experiences fatigue and discomfort during long-term use due to poor weight distribution and balance

Engineering Contradiction:
Improveuser comfortVSAvoidhousing design complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by arranging the motor housing, handle, and cutting attachment in a non-symmetric radial configuration around the central housing section. The motor housing extends in a first radial direction, the handle in a second radial direction, and the cutting attachment in a third radial direction, creating an asymmetric layout that optimizes weight distribution and balance for ergonomic operation.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent transitions from a conventional linear or planar arrangement to a three-dimensional radial configuration. All three main components (motor housing, handle, cutting attachment) are arranged radially around the central housing section, utilizing spatial distribution in multiple dimensions to achieve optimal weight balance and ergonomics.

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

2Ease of operation

If the handle, motor housing, and cutting attachment are arranged radially around the central housing section, then ergonomic operation is achieved, but the manufacturing and assembly process becomes more complex

Engineering Contradiction:
Improveergonomic guidanceVSAvoidassembly complexity
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The patent merges the motor housing, handle, and cutting attachment into a unified radial configuration around the central housing section. This integration creates a cohesive structure where all components are positioned relative to a common center, simplifying the overall assembly process despite the three-dimensional arrangement.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The central housing section serves as a universal mounting platform for all three main components (motor housing, handle, cutting attachment). This multi-functional central structure provides standardized mounting interfaces and alignment references, facilitating manufacturing and assembly despite the complex radial arrangement.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If the device components are distributed radially to achieve balance, then weight distribution is improved, but the device occupies more space in multiple directions

Engineering Contradiction:
Improveweight distributionVSAvoiddevice footprint
Core Design Contradiction:
Ease of operationVSVolume of moving object

Solution Approach 1:

The patent utilizes three-dimensional radial distribution around the central housing section to achieve weight balance. By arranging components radially in space rather than linearly, the device achieves optimal weight distribution while maintaining a compact overall footprint, as the components are distributed around a central axis rather than extending in a single direction.

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

Data Source

PatentEP3321049B1Hand-held, portable cutting device with a cutting fitting
Publication Date: 2021.02.24 ANDREAS STIHL AG & CO KG
  • EP3321049B1 patent drawingFigure 1
  • EP3321049B1 patent drawingFigure 2
  • EP3321049B1 patent drawingFigure 3

AI summary

The invention relates to a hand-held, portable cutting device (1) with a cutting assembly (3) having a longitudinal axis (13). A drive connection (15) between an electric drive motor (5) and the cutting assembly (3) is arranged in a central housing section (2) of the cutting device (1), with a motor housing (4) extending from the central housing section (2) along a longitudinal axis (23). A handle (6) extends from the central housing section (2) along a longitudinal axis (33). The cutting assembly (3) consists of a guide rail (19) with a saw chain (20) rotating on it, wherein, in side view of the cutting device (3), the intersection point (S1) between the longitudinal axis of the handle (33) and the longitudinal axis of the motor housing (23) and the intersection point (S2) between the longitudinal axis of the handle (33) and the longitudinal axis of the cutting assembly (13) are located in the central housing section (2).