Integrating Crankshaft Isolator and Alternator Decoupler
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Solution Overview
Problem
Diesel and gasoline engine accessory drive systems face increased vibrations and belt slip issues due to higher crankshaft vibrations and alternator inertia, leading to belt chirp noise and reduced belt life, which existing crankshaft isolators and alternator decouplers cannot adequately address without increasing system cost.
Innovation Solution
An isolating decoupler with a radially extending arm having a frictional surface slidingly engaged with a pulley inner surface, a spring with intermittent engagement, and an elastomeric member for damping, allowing for efficient decoupling and re-coupling to manage engine vibrations and torque transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crankshaft isolator and alternator decoupler are used together to eliminate belt slip and vibrations, then belt life and system reliability are improved, but system cost increases significantly
Solution Approach 1:
The patent combines the functions of a crankshaft isolator and alternator decoupler into a single integrated decoupler assembly. The assembly includes a crankshaft pulley with damping elements (elastomeric material) to isolate vibrations, and a decoupler mechanism with friction surfaces and springs to prevent belt slip. By merging these previously separate components into one unit, the invention eliminates the need for multiple separate parts, thereby reducing system cost while maintaining the dual functionality of vibration isolation and belt slip prevention.
Solution Approach 2:
The integrated decoupler assembly performs multiple functions simultaneously: it acts as both a crankshaft isolator (through elastomeric damping elements that reduce vibrations) and an alternator decoupler (through friction surfaces and springs that prevent belt slip). This multi-functional design allows a single component to replace what previously required two separate components, addressing the technical contradiction by improving reliability through comprehensive protection while reducing device complexity by eliminating redundant parts.
2Reliability
If traditional crankshaft isolators are used to filter vibrations, then vibration filtering in engine running speed range is improved, but belt slip during engine start-up or shut-down cannot be resolved
Solution Approach 1:
The integrated decoupler assembly combines vibration isolation capabilities (through elastomeric damping elements) with belt slip prevention capabilities (through friction surfaces and spring mechanisms). This multi-functional design allows the single component to effectively address both vibration filtering during normal engine operation and belt slip prevention during engine start-up or shut-down, thereby expanding the operational range coverage without sacrificing vibration filtering performance.
Solution Approach 2:
The decoupler mechanism incorporates dynamic elements including friction surfaces that engage during high-stress conditions (engine start-up or shut-down) and elastomeric damping elements that operate during normal running conditions. The spring-loaded design allows the friction surfaces to engage when needed to prevent belt slip, while the elastomeric material provides continuous vibration damping. This dynamic adaptation to different operating conditions enables the system to maintain effectiveness across the full operational range.
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 decoupler effectively reduces engine vibrations, prevents belt slip, and extends belt life by providing a cost-effective solution that integrates with existing systems without the need for multiple components, enhancing the overall efficiency and reliability of the accessory drive system.
Implementation Method 1
an elastomeric member disposed between the spring and the radially extending arm
Implementation Method 2
an elastomeric member disposed between the spring and the radially extending arm
Implementation Method 3
a spring fixed to the pulley, the spring intermittently engageable with the radially extending arm
Implementation Method 4
a radially extending arm having a frictional surface slidingly engaged with a pulley inner surface
Data Source
AI summary
An isolating decoupler comprising a pulley having a pulley inner surface, a hub having a radially extending arm, the radially extending arm having a frictional surface slidingly engaged with the pulley inner surface, a spring fixed to the pulley, the spring intermittently engageable with the radially extending arm, an elastomeric member disposed between the spring and the radially extending arm; and the radially extending arm intermittently engageable with a pulley stop.