Decoupling Isolator for Engine Belt Vibration and Slip
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Solution Overview
Problem
Current engine accessory drive systems face belt chirp noise and reduced belt life due to increased crankshaft vibrations, which existing crankshaft isolators and alternator decouplers cannot fully address, especially during engine start-up or shut-down, leading to increased costs when both are required together.
Innovation Solution
A decoupling isolator featuring a flat wire spiral spring engagable with a stop to limit pulley rotation, which absorbs angular vibrations during engine operation and allows free rotation during deceleration, effectively reducing belt slip and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crankshaft isolator is used to filter vibrations during engine operation, then vibration filtering is improved, but the isolator presents problems during engine start-up or shut-down due to its natural frequency
Solution Approach 1:
The patent employs a one-way clutch mechanism that allows the pulley to rotate freely in the direction of engine rotation while preventing rotation in the opposite direction. This dynamic behavior enables the isolator to adapt to different engine operation phases: during normal operation, the spring provides vibration filtering; during start-up and shut-down, the free rotation capability prevents the isolator from interfering with belt tensioning, thus resolving the contradiction between vibration filtering performance and adaptability across all engine phases.
Solution Approach 2:
The isolator is divided into functionally independent components: a vibration isolation system (spring and damper) and a free rotation system (one-way clutch). This segmentation allows each subsystem to perform its specific function independently - the spring-damper handles vibration filtering during operation, while the one-way clutch enables free rotation during start-up and shut-down, thereby resolving the contradiction between these two operational requirements.
2Reliability
If an alternator decoupler is used to eliminate belt slipping at the alternator pulley, then belt slip at alternator is reduced, but belt slip at the crankshaft pulley cannot be resolved
Solution Approach 1:
The patent combines the functions of a crankshaft isolator and an alternator decoupler into a single integrated device. The one-way clutch mechanism provides decoupling functionality similar to an alternator decoupler, preventing belt slip at the crankshaft pulley, while the spring-damper system provides vibration isolation. This merging of functions resolves the contradiction by enabling the device to address belt slip at the crankshaft pulley while maintaining its vibration isolation capabilities.
3Reliability
If both a crankshaft isolator and alternator decoupler are used together to address all belt slip and vibration issues, then comprehensive protection is achieved, but system cost increases significantly
Solution Approach 1:
The patent designs a universal isolator that performs multiple functions: vibration isolation through the spring-damper system, belt slip prevention through the one-way clutch mechanism, and adaptation to different engine operation phases. This multi-functional design eliminates the need for separate crankshaft isolators and alternator decouplers, thereby reducing system complexity and cost while maintaining comprehensive protection against belt slip and vibration issues.
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 decoupling isolator effectively reduces belt slip and noise across engine operation cycles, extending belt life and reducing system costs by integrating the functions of both crankshaft isolators and alternator decouplers into a single component.
Implementation Method 1
a flat wire spiral spring having an end fixedly connected to the pulley, the flat wire spiral spring having another end engageable with the stop to limit a rotation of the pulley
Data Source
AI summary
A decoupling isolator comprising a pulley, a hub member comprising a stop, a flat wire spiral spring having an end fixedly connected to the pulley, the flat wire spiral spring having another end engageable with the stop to limit a rotation of the pulley.