Belt Pulley Decoupler Sleeve Geometry for Spring Centering
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Solution Overview
Problem
Generic belt pulley decouplers experience disruptive imbalances due to rotational speed differences and deviations in coaxiality of the helical torsion spring, leading to inefficiencies in torque transmission and vibration compensation.
Innovation Solution
The inner diameter of the driver sleeve is reduced towards the spring end, allowing the wrap-around band to be optimally centered, eliminating the need for radial indentations and simplifying assembly by adapting the winding diameter to match the sleeve's inner diameter, thereby enhancing balance and reducing operational friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the wrap-around band end is designed with radial indentations to center the spring end, then the centering precision is improved, but the device complexity increases
Solution Approach 1:
The driver sleeve is designed with a conical inner lateral surface where the diameter varies along the axial direction. The inner diameter decreases toward the spring end, creating a tapered geometry that provides centering function locally at the spring end region without requiring radial indentations. This local geometric variation achieves precise centering while maintaining overall structural simplicity.
2Manufacturing precision
If the radial gap between the wrap-around band and helical torsion spring is reduced to improve centering, then the centering quality is improved, but the assembly difficulty increases
Solution Approach 1:
The wrap-around band is designed with a flexible cylindrical geometry that can dynamically adapt its winding diameter to match the varying inner diameter of the conical driver sleeve. This dynamic adaptability allows the band to conform to the tapered surface during assembly, achieving optimal centering and contact without requiring precise pre-adjustment of radial gaps or complex assembly procedures.
3Manufacturing precision
If the inner diameter of the driver sleeve is reduced toward the spring end to center the wrap-around band, then the balancing is improved, but the manufacturing complexity increases
Solution Approach 1:
The driver sleeve employs an asymmetric conical geometry where the inner diameter varies continuously or in stages along the axial direction, being smaller at the spring end and larger at the opposite end. This asymmetric tapering creates a self-centering effect for the wrap-around band and helical torsion spring assembly, improving balancing by ensuring coaxial alignment without requiring additional balancing components or complex multi-part structures.
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
This design improves the balancing of the belt pulley decoupler, reducing imbalance and operational friction, and simplifies assembly, leading to more efficient torque transmission and vibration compensation.
Implementation Method 1
the resilience of the helical torsion spring connected in series with the wrap-around band smooths the torsional irregularities originating from the belt drive
Implementation Method 2
The wrap-around band acts as a one-way clutch which, when closed, transfers torque from the belt pulley to the hub
Data Source
AI summary
The disclosure relates to a belt pulley decoupler for transmitting torque between the belt of a belt drive and a shaft in driving connection therewith. The belt pulley decoupler includes a hub, a belt pulley, and a series circuit of a helical torsion spring, a wrap-around band, which surrounds the helical torsion spring with a radial gap, and a driver sleeve, which surrounds the wrap-around band and transmits the torque between the wrap-around band and the helical torsion spring. An outer periphery of the wrap-around band is in frictional contact with an inner lateral surface, which rotates conjointly with the belt pulley, and the outer periphery of the wrap-around band is also in frictional contact with the inner lateral surface of the driver sleeve. An end of the helical torsion spring is in contact with a radially inwardly extending spring plate of the driver sleeve.