Torsion Spring Isolator Decoupler for Belt Chirp Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Diesel and gasoline engine accessory drive systems experience increased vibrations and belt chirp noise due to higher crankshaft vibrations and alternator inertia, leading to reduced belt life and noise issues, which existing crankshaft isolators and decouplers fail to adequately address.
Innovation Solution
An isolator decoupler with a torsion spring and pulley having a predetermined clearance, where the torsion spring outside diameter surface progressively engages the pulley inside diameter surface through radial expansion, providing a torque-dependent frictional engagement to manage vibrations and prevent overloading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a torsion spring is used to isolate vibrations, then vibration isolation is improved, but the spring may be overloaded during high torque conditions
Solution Approach 1:
The pulley acts as an intermediary element between the torsion spring and the belt drive system. During high torque conditions, the pulley makes contact with the torsion spring, providing a mechanical stop that prevents the spring from being overloaded while still allowing the spring to function as a vibration isolator during normal operating conditions.
Solution Approach 2:
The design incorporates a predetermined clearance between the pulley and torsion spring that is carefully engineered to allow the spring to deflect under normal vibrations while preventing excessive deflection under high torque loads. This beforehand cushioning approach protects the spring from overload before damage can occur.
2Strength
If the torsion spring is constrained to prevent overloading, then spring protection is improved, but vibration isolation capability deteriorates
Solution Approach 1:
The system transitions from a static constraint to a dynamic solution where the pulley only contacts the torsion spring when necessary (during high torque conditions). During normal vibration isolation operations, the predetermined clearance allows the spring to flex freely, maintaining vibration isolation capability while providing protection when needed.
3Stability of the object's composition
If a clearance is provided between torsion spring and pulley, then vibration isolation is improved, but belt chirp noise increases
Solution Approach 1:
The invention optimizes the predetermined clearance parameter to a specific value that balances two competing requirements: it is large enough to allow the torsion spring to isolate vibrations effectively, but small enough to prevent excessive belt slip and chirp noise. This parameter optimization resolves the contradiction between vibration isolation and noise control.
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
Effectively reduces belt chirp noise and extends belt life by managing torque loads and decoupling the alternator and engine during deceleration, preventing shock and ensuring the torsion spring is protected from excessive loads.
Implementation Method 1
torque load dependent radial expansion of the torsion spring
Implementation Method 2
torsion spring outside diameter surface and a pulley inside diameter surface come into a progressive frictional engagement
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
An isolator decoupler comprising a shaft (10), a pulley (30) journalled to the shaft (10), a clutch carrier (50) journalled to the shaft (10) through a one-way clutch (60), a torsion spring (40) engaged between the pulley and the clutch carrier, the torsion spring loadable in an unwinding direction, the torsion spring and the pulley having a predetermined clearance between a torsion spring outside diameter surface and a pulley inside diameter surface, and whereby the torsion spring outside diameter surface and a pulley inside diameter surface come into a progressive frictional engagement by torque load dependent radial expansion of the torsion spring.