Flexible Membrane Decoupler for Shaft Misalignment and Vibration Isolation
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Solution Overview
Problem
Current decouplers for alternators and belt-driven integrated starter-generators (BISG) in engine front-end accessory drive systems fail to effectively compensate for axial, lateral, and angular displacements, leading to unwanted noise and vibrations due to their rigidity, which limits their ability to isolate inertia over a broader frequency range.
Innovation Solution
A flexible laminated membrane decoupler with non-linear torsional stiffness is introduced, capable of compensating for these displacements by flexing in multiple dimensions, eliminating the need for hydraulic fluids and providing enhanced inertia isolation across a wider frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rigid decoupler is used, then the structure is simple and manufacturing is easy, but it cannot compensate for axial, lateral, and angular displacements, resulting in unwanted noise and vibrations
Solution Approach 1:
The patent employs a flexible membrane structure with laminated construction that can flex and deform to accommodate axial, lateral, and angular displacements between the pulley and alternator shaft, while still providing effective vibration isolation and noise reduction without requiring complex rigid mechanisms
Solution Approach 2:
The decoupler transitions from a static rigid structure to a dynamic flexible membrane system that can adapt its shape and stiffness characteristics in response to varying operating conditions and displacement types, enabling continuous vibration mitigation across different engine speeds and loads
2Reliability
If the flexible membrane thickness is increased to improve vibration isolation, then the inertia isolation performance improves, but the flexibility to compensate for displacements decreases
Solution Approach 1:
The flexible membrane is constructed as a laminated structure composed of multiple thin layers bonded together, where each layer contributes to the overall stiffness and flexibility characteristics. This segmented approach allows the membrane to bend and flex more easily than a solid membrane of equivalent thickness, maintaining displacement compensation capability while providing sufficient vibration isolation
Solution Approach 2:
The flexible membrane utilizes composite material construction with multiple layers that may have different material properties, creating a structure with tailored mechanical characteristics that balance flexibility for displacement accommodation with sufficient stiffness for vibration isolation across the operating range
3Ease of manufacture
If traditional decoupler designs with identical spring parameters are used, then the manufacturing process is simple, but the decoupler can only effectively isolate within a small frequency range
Solution Approach 1:
The flexible membrane incorporates spatially varying thickness and stiffness characteristics, with different regions of the membrane having different local properties optimized for specific frequency ranges and displacement types, enabling broad frequency range vibration isolation while maintaining a relatively simple overall structure and manufacturing process
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 flexible laminated membrane decoupler effectively reduces vibrations and noise across a greater frequency range, improving user experience by mitigating resonances and maintaining performance under varying engine conditions without the need for hydraulic fluids or complex manufacturing processes.
Implementation Method 1
The flexible membrane decoupler may comprise a non-linear torsional stiffness which may allow it to mitigate vibrations and noises at a greater range than the previous example described above. The decoupler may compensate for axial, lateral, and angular displacements between the drive shaft and the one-way clutch by flexing in a desired direction
Implementation Method 2
To reduce the vibration of alternator or BISG, the slips of belt and the alternator or BISG pulley, and the impact of the alternator or BISG to FEAD system, the vibration between the alternator or BISG and the FEAD system is to be decoupled. This demands a suitable torsional spring stiffness and damping.
Implementation Method 3
However, when the pulley decelerates relative to the alternator or BISG shaft, the one-way clutch is disengaged, and the alternator rotor and its shaft will overrun and rotate freely.
Data Source
AI summary
Methods and systems are provided for an isolator. In one example, system may include an isolator comprising a flexible laminated membrane comprising a non-linear torsional stiffness for compensation of axial, lateral, and angular displacements between a drive shaft and a clutch.