Chainsaw Guide Bar Clamping for Quick High-Force Chain Tensioning

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Solution Overview

Problem

Motorized chain saws with quick-release devices for saw chain tensioning face challenges in transmitting high forces to the guide rail, making tensioning and re-tensioning of the saw chain complicated and time-consuming.

Innovation Solution

A motor chainsaw design featuring a fixed part and a movable guide rail with multiple friction contact surfaces, where the guide rail is clamped between the fixed part and a clamping element, allowing for easy and quick tensioning by increasing the number of friction contact surfaces and frictional forces, enabling high force transmission without shifting relative to the fixed part.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a quick-release chain tensioning device is used, then chain tensioning becomes simple and quick, but the ability to transmit high forces from the guide bar to the housing deteriorates

Engineering Contradiction:
Improvechain tensioning operationVSAvoidforce transmission capability
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The clamping mechanism is divided into multiple independent contact surfaces (first clamping surface, second clamping surface, third clamping surface) that work together to transmit forces. Each surface contributes to the overall force transmission capability while maintaining the quick-release function through the movable clamping element

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solution transitions from a single-point or single-surface clamping approach to a multi-surface distributed clamping system. By arranging multiple contact surfaces in different spatial orientations around the guide bar, the system achieves both easy operation (through the movable clamping element) and high force transmission (through the cumulative effect of multiple friction surfaces)

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

2Force

If high forces are transmitted from the guide bar to the housing, then power transmission is improved, but chain tensioning becomes complicated and time-consuming

Engineering Contradiction:
Improveforce transmission capabilityVSAvoidchain tensioning time
Core Design Contradiction:
ForceVSLoss of time

Solution Approach 1:

The clamping element is designed to be movable along the longitudinal axis, allowing dynamic adjustment between a released state (for quick chain tensioning) and a clamped state (for high force transmission). This dynamic capability enables the system to switch between operational modes without manual intervention, reducing time loss

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The force transmission path is segmented into multiple contact surfaces that collectively bear the load. This segmentation allows the system to achieve high total force transmission capacity while each individual surface can be easily engaged or disengaged by moving the clamping element, thus maintaining quick adjustment capability

Inventive Principle:
Principle #1Segmentation

3Force

If multiple friction contact surfaces are added to increase force transmission, then the number of contact surfaces increases, but the device complexity increases

Engineering Contradiction:
Improvefrictional force transmissionVSAvoidclamping mechanism complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The movable clamping element serves multiple functions simultaneously: it applies clamping force through multiple contact surfaces for high frictional force transmission, maintains a simple operational interface for chain tensioning, and provides structural support for the entire clamping mechanism. This multi-functionality reduces the need for additional separate components

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

Solution Approach 2:

Multiple clamping surfaces are merged into a single integrated clamping element structure that can be moved as one unit. This merging allows the system to achieve the mechanical equivalent of multiple independent clamping mechanisms while maintaining the simplicity of a single actuator, thus reducing overall device complexity

Inventive Principle:
Principle #5Merging (Combining)

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 design allows for simple and quick tensioning of the saw chain, even under high loads, with increased frictional forces transmitted between the movable and fixed parts, ensuring precise tensioning and reduced wear on contact surfaces.

Implementation Method 1

At least one of the surfaces facing each other between the end of the guide bar and the housing or the clamping element is treated to increase friction. This allows higher forces to act on the clamping mechanism with the same clamping force, without the guide bar shifting.

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3385045B1Power chain saw
Publication Date: 2022.01.26 ANDREAS STIHL AG & CO KG
  • EP3385045B1 patent drawingFigure 1
  • EP3385045B1 patent drawingFigure 2~5
  • EP3385045B1 patent drawingFigure 6

AI summary

The invention relates to a motorized chainsaw with a drive motor (5). The motorized chainsaw (1) has a stationary part (2) and a movable part (8). The guide bar (28) is clamped between the stationary part (2) and a clamping element (3) and held against the stationary part (2). The movable part (8) is displaceable in a longitudinal direction (11) relative to the stationary part (2) for tensioning the saw chain (7) when the clamping element (3) is released. The motorized chainsaw (1) has a stop surface (12) and a clamping surface (4). Between the stop surface (12) and the clamping surface (4), at least one additional contact surface (13.1-13.10) is rigidly connected to the stationary part (2) in the longitudinal direction (11), and at least one additional contact surface (14.2-14.12) is rigidly connected to the movable part (8) in the longitudinal direction. All contact surfaces (13.1-13.10, 14.1-14.12) are located one after the other in the force flow from the clamping element (3) to the fixed part (2).