Isolating Decoupler Assembly for Belt Chirp and Compact Packaging
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Solution Overview
Problem
Diesel and gasoline engine accessory drive systems experience increased belt chirp noise and reduced belt life due to higher crankshaft vibrations and alternator inertia, which existing crankshaft isolators and decouplers struggle to effectively mitigate.
Innovation Solution
An isolating decoupler design featuring a shaft with an inner race bearing, a torsion spring welded to a one-way clutch, and another end welded to a pulley, which reduces axial length and facilitates use in smaller engine compartments, while employing welding techniques like MIG, SMAW, TIG, and laser welding for secure connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional interference or press fit connections are used between components, then mechanical strength and reliability are improved, but manufacturing complexity and assembly difficulty increase
Solution Approach 1:
The patent combines multiple connection methods (interference fit, welding, and mechanical keys) into a unified hybrid connection system. The shaft connects to the pulley through both interference fit and welding, while also incorporating a key-way mechanism for mechanical locking, creating a multi-modal connection that leverages the strengths of each method simultaneously
Solution Approach 2:
The connection system employs composite joining techniques combining metallic bonding (welding) with mechanical interference fits and keyed connections. This composite approach creates a connection system that is more reliable than any single method alone while maintaining manufacturing feasibility through standardized processes
2Ease of manufacture
If the decoupler design uses traditional mechanical connections with discrete components, then ease of manufacture is improved, but the axial length increases making it unsuitable for compact engine compartments
Solution Approach 1:
The patent implements nesting by placing the bearing internally within the shaft structure, with the key-way mechanism nested within the bearing assembly, and the pulley nested over the shaft. This nested arrangement eliminates the need for separate mounting features and reduces the overall axial length while maintaining manufacturing simplicity
Solution Approach 2:
The shaft is designed to combine multiple functions in a single component: it provides structural support, serves as the bearing mounting surface, contains the key-way for mechanical connection, and acts as the rotational element for the pulley. This merging of functions eliminates the need for separate discrete components that would increase axial length
3Strength
If welding is used to join the torsion spring to the one-way clutch and pulley, then connection strength is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates preliminary positioning features such as locating pins, pre-drilled holes, and precision-machined surfaces that ensure accurate alignment of components before welding begins. These preliminary actions establish the correct geometry and position, reducing the precision burden on the welding operation itself to only achieving proper fusion and bond strength
Solution Approach 2:
The design employs intermediary elements such as定位 fixtures, jigs, and pre-assembled subcomponents that act as mediators between the manufacturing process and the final welded joint. These intermediaries ensure consistent positioning and alignment, allowing the welding process to focus on creating strong bonds rather than achieving precise geometric alignment
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 belt chirp noise and extends belt life by efficiently managing increased crankshaft vibrations and alternator inertia, ensuring reliable operation in compact engine spaces.
Implementation Method 1
a torsion spring engaged between the one-way clutch and the pulley
Implementation Method 2
the torsion spring having an end welded to the one-way clutch and having another end welded to the pulley
Implementation Method 3
a one-way clutch engaged with the shaft
Implementation Method 4
a pulley journalled to the shaft on at least one bearing
Data Source
AI summary
An isolating decoupler comprising a shaft, a pulley journalled to the shaft on at least one bearing, a one-way clutch engaged with the shaft, a torsion spring engaged between the one-way clutch and the pulley, the shaft comprises an inner race of the at least one bearing, and the torsion spring having an end welded to the one-way clutch and having another end welded to the pulley.