Chain Saw Chain Lifting Mechanism for Precise Tensioning
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Solution Overview
Problem
Re-tensioning a motor chainsaw saw chain is difficult for private users due to the challenge of selecting the correct tensioning force, leading to increased wear or loose chain issues, especially in low-engine power tools like wood trimmers, where the adjustment range is small.
Innovation Solution
A motor chainsaw with a chain lifting device that deflects the saw chain during tensioning to set a predetermined chain play, avoiding excessive tension and friction, and includes a spring element for automatic pre-tensioning, allowing easy adjustment through a two-stage tensioning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the operator tensions the saw chain manually without assistance, then the tensioning process can be performed, but the operator cannot select the correct tension due to lack of experience, leading to excessive wear or loose chain issues
Solution Approach 1:
The chain lifting device automatically deflects the saw chain by a predetermined amount when the guide bar is moved during tensioning, eliminating the need for the operator to manually adjust the chain tension. The system performs the deflection action automatically, allowing the operator to simply move the guide bar while the device handles the precise chain tensioning
Solution Approach 2:
The chain lifting device acts as an intermediary mechanism between the guide bar movement and the saw chain. When the guide bar is moved forward or backward during tensioning, the chain lifting device mediates by deflecting the chain by a predetermined amount, ensuring correct tension is achieved without requiring operator expertise
2Reliability
If the saw chain is tensioned too tightly, then the chain remains secure, but friction between the chain and guide bar increases leading to accelerated wear
Solution Approach 1:
The chain lifting device changes the physical state of the chain by deflecting it by a predetermined amount during tensioning. This parameter change in chain position ensures the chain is not overtightened, maintaining optimal friction levels while keeping the chain secure on the guide bar
3Adaptability or versatility
If the saw chain is tensioned with a small adjustment range, then the chain tension can be controlled, but it becomes difficult to achieve the correct tension for low engine power tools
Solution Approach 1:
The chain lifting device performs the complex chain deflection action automatically based on the movement of the guide bar, eliminating the difficulty of manual tension adjustment. The operator simply needs to move the guide bar, and the device automatically achieves the correct chain tension within the limited adjustment range
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
Enables easy and reproducible saw chain tensioning, reducing wear and preventing chain loosening, while maintaining optimal friction levels, thus enhancing operator safety and tool longevity.
Implementation Method 1
The tensioning device (10) is designed with a spring element (14) which exerts a spring force on the guide bar (5) in the direction of its longitudinal axis (6) away from the drive sprocket (4)
Implementation Method 2
The chain lifting device (11) is designed to deflect the saw chain (7) in a deflected position (40) when the tensioning device (10) is tensioning the saw chain (7)
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The invention relates to a motor chainsaw with a housing (2) and a drive motor (3). The guide bar (5) is held on the housing (2) by a releasable fastening device (8) and, when the fastening device (8) is released, is displaceable relative to the housing (2) in the direction of its longitudinal axis (6) by means of a tensioning device (10). The motor chainsaw (1) includes a chain lifting device (11) designed separately from the tensioning device (10). The chain lifting device (11) is designed to deflect the saw chain (7) in a deflection position (40) of the chain lifting device (11) when the tensioning device (10) tensions the saw chain (7), and to release the saw chain (7) in an operating position (41) of the chain lifting device (11) when the guide bar (5) is fixed.