Double Acting Spring Isolator for Engine Crankshaft Noise Reduction
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Solution Overview
Problem
Existing isolators fail to effectively isolate torque vibrations between the engine crankshaft and endless drive members in vehicles, particularly in engines with specific cylinder counts and during startup and acceleration, leading to inefficiencies and noise due to inadequate torque transfer mechanisms.
Innovation Solution
A double-acting spring system with a pulley and shaft adapter, featuring arcuate compression springs and pivotable drivers, is used to isolate torque vibrations by transferring torque between the crankshaft and endless drive member, with strategically designed drive surface spacings to manage kinetic energies and reduce noise during transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional isolator is used to isolate torque vibrations between crankshaft and endless drive member, then vibration isolation is provided, but noise and kinetic energy during torque transfer transitions are not sufficiently reduced
Solution Approach 1:
The patent introduces an intermediary mechanism consisting of drive surfaces with strategic spacing between the adapter and pulley. This intermediary spacing acts as a buffer that controls the timing and manner of spring engagement, reducing impact kinetic energy and noise during torque transfer transitions while maintaining effective torque transmission through the spring system.
Solution Approach 2:
The patent employs beforehand cushioning by designing drive surfaces with angular spacing that creates a controlled transition zone. This spacing allows the spring system to engage gradually rather than through sudden impact, cushioning the torque transfer process and reducing harmful kinetic energy spikes and noise before full torque transmission occurs.
2Loss of energy
If torque is transferred directly from shaft adapter to pulley, then power transfer efficiency is maintained, but kinetic energy spikes and noise occur during transition between torque transfer directions
Solution Approach 1:
The patent applies dynamics by making the torque transfer path adaptable through the strategic spacing of drive surfaces. The system dynamically transitions between different engagement states of the spring system based on the direction and magnitude of torque, allowing smooth reversal of torque transfer direction without kinetic energy spikes, thus reducing energy loss while maintaining productivity.
Solution Approach 2:
The patent utilizes parameter changes by varying the angular spacing of drive surfaces on the adapter and pulley. This parameter optimization ensures that springs engage and disengage at controlled rates during torque direction transitions, reducing kinetic energy loss while maintaining efficient power transfer through the isolator system.
3Object-affected harmful factors
If springs are engaged with preload, then torque transfer is maintained, but noise and impact occur during neutral position transitions
Solution Approach 1:
The patent employs asymmetry in the drive surface spacing configuration, where the angular spacing on the adapter differs from that on the pulley. This asymmetric design creates a neutral zone that allows the spring system to pass through the neutral position without impact, reducing noise while maintaining torque transfer capability through the non-uniform engagement geometry.
Solution Approach 2:
The patent segments the torque transfer process into distinct phases through the strategic spacing of drive surfaces. By dividing the engagement into controlled stages with a neutral transition zone, the system eliminates impact noise during direction reversals while maintaining continuous torque transfer capability through the segmented engagement sequence.
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 solution significantly reduces kinetic energies and noise during torque transfer, enhancing the isolation of vibrations and improving the efficiency of power transfer between the crankshaft and endless drive member, particularly in engines with BAS systems.
Implementation Method 1
two arc compression springs that are located between two stops of the spring tray without preload
Implementation Method 2
double acting spring system includes two arc compression springs
Implementation Method 3
The ends of the springs are fixed on the pins mounted on the plastic guides
Implementation Method 4
Torque is transferrable from the shaft adapter to the spring through the first spring end, and from the spring to the pulley through the second spring end
Data Source
AI summary
An isolator is provided for use with an engine and in particular an engine that is assisted or started by MGU (Motor-Generator Unit) or a motor through an endless drive member. It comprises a double acting spring system for isolating crankshaft pulley from torsion vibration at the crankshaft, and in extreme conditions, such as during engine startup and accelerations or decelerations of the engine crankshaft relative to the pulley and when isolator operates in an “engine-driven” mode with the engine crankshaft is driven by the belt.