Centrifugal Clutch Drum with Localized Thickness
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Solution Overview
Problem
Conventional centrifugal clutches in hand-held power tools are heavy and wide, limiting their maneuverability and increasing vibration and noise due to resonance with the crankshaft system.
Innovation Solution
A clutch drum design with a thinner end portion compared to the peripheral portion, reducing overall width and weight, allowing for a lighter and more versatile tool by using thinner sheet metal and optimizing the brake band contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the clutch drum is made with sufficient thickness to withstand load from weighted arms, then the strength is improved, but the weight and width increase
Solution Approach 1:
The clutch drum is designed with non-uniform thickness: the peripheral portion has greater thickness to withstand the load from weighted arms, while the end portion has reduced thickness since it does not bear the same load. This local differentiation of thickness optimizes strength where needed while reducing weight and width where full thickness is not required.
2Weight of moving object
If the clutch drum width is reduced, then the weight and maneuverability are improved, but the brake band contact area is reduced
Solution Approach 1:
The brake band contact area is concentrated on the peripheral portion of the clutch drum, which maintains sufficient width and thickness. The end portion thickness is reduced without affecting the brake band contact area, as the braking function is localized to the peripheral portion where the brake band applies friction.
3Object-affected harmful factors
If the clutch drum width is reduced, then the resonant frequency is shifted away from working frequency, but the structural integrity may be compromised
Solution Approach 1:
The clutch drum employs differentiated thickness distribution: the peripheral portion maintains sufficient thickness to ensure structural integrity and withstand operational loads, while the end portion has reduced thickness to shift the resonant frequency away from the working frequency, reducing vibration and noise during operation.
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 reduced width and weight of the clutch drum lead to less vibration, reduced noise, and extended service life by shifting the resonant frequency away from operational frequencies, resulting in a more efficient and user-friendly hand-held power tool.
Implementation Method 1
When the engine rpm is increased and this increases the centrifugal force acting on a movable member of the centrifugal clutch and clutch engagement results
Data Source
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AI summary
The present invention provides a clutch drum (7) being a part of a centrifugal clutch (4) for an internal combustion engine (1). The centrifugal clutch (4) is arranged to transmit a rotational motion of a crank shaft (2) at higher engine speed and to declutch at lower engine speed. The clutch drum (7) includes a peripheral portion (8), with thickness B, which is arranged to be engaged on the inside by weighted arms of a driving disc (5) at higher engine speed and the clutch drum further includes an end portion (9), with thickness A, joining a drum hub (13) and the peripheral portion (8), and the thickness A is less than the thickness B.