Tertiary Chain Lacing for NVH Reduction
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Solution Overview
Problem
Traditional silent or inverted tooth chain lacing with a constant pitch frequency results in high noise vibration and harshness (NVH), which is unsatisfactory for engine users, and previous methods using two different link profiles only partially address this issue by creating a random noise pattern that is difficult to discern.
Innovation Solution
A random pattern chain assembly using at least three different link types arranged in a specific pattern where the first link type is never adjacent to the third link type, with a second link type acting as an intermediate to provide a more gradual transition between engagement styles, reducing NVH by altering the pitch frequency and engagement differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant pitch frequency chain lacing is used, then the chain structure is simple and easy to manufacture, but the noise vibration and harshness (NVH) performance deteriorates
Solution Approach 1:
The chain lacing is segmented into multiple distinct patterns (first, second, and third patterns) that alternate along the chain. Each pattern uses different link profiles with varying pitch frequencies, thereby breaking the constant pitch frequency that causes high NVH while maintaining manufacturability through systematic segmentation.
Solution Approach 2:
Different sections of the chain are assigned different link profiles and pitch frequencies according to specific patterns. The first link profile is used in certain positions, the second link profile in other positions, and the third link profile in alternating positions, creating local variations in engagement characteristics that reduce overall NVH while preserving structural simplicity.
2Object-affected harmful factors
If two different link profiles are used to disrupt pitch engagement pattern, then the noise characteristic becomes random and difficult to discern, but the ability to tune NVH is limited
Solution Approach 1:
The invention introduces three distinct link profiles with different pitch frequencies and engagement characteristics instead of merely two. This expansion of parameters (adding a third profile with alternating positions) provides greater versatility in tuning NVH performance while maintaining the random noise characteristic that is difficult to discern, allowing for more precise control over the noise spectrum.
3Adaptability or versatility
If three or more link profiles are used with specific patterning, then the NVH tuning capability is improved, but the chain structure complexity increases
Solution Approach 1:
The three link profiles are arranged in periodic alternating patterns where the first and third patterns alternate along the chain, with the second pattern providing intermediate transitions. This periodic structure creates predictable variations in pitch frequency and engagement characteristics, enabling effective NVH tuning while avoiding the chaos of completely random arrangements, thus balancing complexity with performance.
Data Source
AI summary
A random pattern chain assembly of the present invention improves noise, vibration and harshness (NVH) performance of a silent or inverted tooth chain. The chain assembly preferably uses at least three different link types arranged in a known pattern. The pattern is arranged such that the first link type is never adjacent the third link type, in that there is always a second link type between the first link type and the third link type.