Phased Chain Sprocket Harmonic Cancellation
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Solution Overview
Problem
Vehicles experience undesirable noise, vibration, and harshness (NVH) due to the constant contact between components like chains and sprockets or gears in transmissions and transfer cases, which reduces efficiency and durability and causes discomfort for occupants.
Innovation Solution
The method involves replicating and delaying equivalent components relative to the original components by a predetermined amount to phase their repeating events, thereby reducing specific harmonics in the NVH spectrum, using the Fourier theorem to describe and minimize harmonics, and applying symmetrical or asymmetrical delaying techniques to achieve optimal NVH reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If components like chains and sprockets or gears are used to transfer torque in transmissions and transfer cases, then torque transfer function is achieved, but undesirable noise, vibration, and harshness (NVH) are produced due to constant contact between components
Solution Approach 1:
The patent applies periodic action by introducing a phasing mechanism that creates periodic variations in the contact patterns between chains and sprockets or gears. The phasing mechanism periodically adjusts the engagement timing of multiple chain-sprocket or gear pairs, transforming the continuous harmful contact into a periodic pattern that allows for NVH cancellation through destructive interference of vibration harmonics.
Solution Approach 2:
The patent converts the harmful NVH generated by component contact into a beneficial effect by using the same contact mechanisms to create counter-phase vibrations. The vibrations that were originally harmful are now utilized in a controlled manner to cancel each other out through phasing, transforming the noise and vibration problem into a solution that actively reduces NVH while maintaining torque transfer.
2Object-generated harmful factors
If equivalent components are replicated and delayed to phase repeating events for NVH reduction, then dominant harmonics in NVH spectra are reduced, but device complexity increases due to multiple replications
Solution Approach 1:
The patent applies segmentation by dividing the torque transfer function into multiple separate chain-sprocket or gear pairs instead of using a single component. Each replicated component is phased relative to the others, allowing the NVH harmonics from each segment to be staggered in time. This segmentation enables independent control of each component's engagement timing to achieve harmonic cancellation while distributing the complexity across multiple simpler, identical units.
3Object-generated harmful factors
If components are phased to cancel dominant harmonics, then NVH reduction is achieved, but force distribution among components may be compromised
Solution Approach 1:
The patent applies dynamics by making the phasing relationship between replicated components adjustable rather than fixed. The phasing mechanism allows the relative timing and engagement phases of multiple chain-sprocket or gear pairs to be dynamically optimized. This enables the system to adapt the force distribution and phasing angles in real-time or during design optimization to simultaneously achieve both NVH reduction through harmonic cancellation and acceptable force distribution across all components.
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
This approach effectively reduces or eliminates undesirable NVH by phasing equivalent components to cancel out dominant harmonics, improving the durability and efficiency of vehicle components while maintaining the distribution of forces, though it may require multiple replications or compromise on delay values.
Implementation Method 1
NVH generated by any repeating event can be described in terms of 'harmonics'. By Fourier theorem, any repeating event F(t) can be described as a linear combination of harmonics.
Data Source
AI summary
A method for reducing NVH in a vehicle having the steps of providing at least one repeating event, replicating at least one component, and delaying at least one equivalent part. The repeating event is a complete cycle, such that the repeating event ends when the cycle begins to repeat itself. The component is replicated at least one time so that at least one equivalent part is formed. The equivalent part is delayed with respect to the component by angularly positioning the equivalent part with respect to the component in a predetermined way, such that at least one harmonic in the NVH-spectra is reduced during the component's repeating event and the equivalent part's repeating event in operation.