Bidirectional Pulley Isolator With Viscous Damping for BSG Systems
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Solution Overview
Problem
Current alternator isolator decouplers are unidirectional, failing to provide effective isolation and decoupling in bidirectional systems like Belt Driven Starter-Generator (BSG) systems, which require expensive crank torsional vibration dampers and high-damping tensioners to manage increased crankshaft vibrations and belt slip noise.
Innovation Solution
A bidirectional isolator with a damping member compressing a damping fluid against a pulley stop, utilizing a torsion spring connected through welds to enable decoupling and torque transmission in both directions, and incorporating a viscous damping mechanism to reduce noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a unidirectional isolator decoupler is used in a bidirectional system, then the isolator can provide isolation in one direction, but it fails to provide effective isolation and decoupling in the reverse direction
Solution Approach 1:
The isolator employs asymmetric friction elements with different friction coefficients for forward and reverse directions. The friction member has a first friction coefficient when engaged with the first friction surface and a second friction coefficient when engaged with the second friction surface, enabling different isolation characteristics in each direction while maintaining bidirectional functionality
Solution Approach 2:
The isolator is designed to perform multiple functions in both directions: torque transmission, vibration isolation, and belt slip control. The friction-based mechanism provides bidirectional torque transmission while the asymmetric friction coefficients enable adaptive isolation for both forward and reverse rotation, making it universally applicable to bidirectional alternator systems
2Object-affected harmful factors
If expensive crank torsional vibration dampers and high-damping tensioners are added to manage crankshaft vibrations and belt slip noise, then vibration and noise control improves, but system cost and complexity increase
Solution Approach 1:
The isolator combines multiple functions into a single integrated component: torque transmission, vibration isolation, and belt slip noise control. The friction member and friction surfaces are integrated into the alternator pulley assembly, eliminating the need for separate dampers and high-damping tensioners, thereby reducing system complexity while maintaining effectiveness
Solution Approach 2:
The isolator converts the harmful effects of crankshaft vibrations and belt slip into useful friction-based damping. The asymmetric friction mechanism dissipates vibration energy and controls belt slip noise through controlled friction, transforming harmful vibrations into beneficial damping effects without requiring additional expensive components
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 solution provides effective isolation and decoupling in both directions, reducing the need for expensive crank dampers and high-damping tensioners, while eliminating impact noise through viscous drag, thus enhancing the performance of Belt Driven Starter-Generator systems.
Implementation Method 1
a damping member compressing a damping fluid against a pulley stop... incorporating a viscous damping mechanism to reduce noise and vibration
Implementation Method 2
a torsion spring connected through welds to enable decoupling and torque transmission in both directions
Data Source
AI summary
An isolator comprising a pulley having a pulley stop, a plate attached to the pulley, a shaft, the pulley journalled to the shaft, a torsion spring attached to the shaft, a damping member attached to the torsion spring, the damping member disposed between the plate and the pulley, and the damping member compressing a damping fluid against the pulley stop.