Inverted Tooth Chain Inner Link Plate Ratio
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Solution Overview
Problem
Inverted tooth chains in internal combustion engines face challenges with wear and fatigue strength due to high stress and manufacturing costs, while existing designs either lead to poor acoustics or increased manufacturing effort.
Innovation Solution
The design features a toothed chain with inner link plates having a plate thickness to web width ratio greater than 1.6, optimized power transmission, and a middle link plate configuration that ensures even force application and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the inner link plates are made wider than the outer link plates (as in DE 203 04 437 U1), then the chain can absorb larger forces, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent applies parameter changes by optimizing the ratio between plate thickness and link width to greater than 1.6. This specific parameter relationship allows the inner link plates to achieve the necessary strength for force absorption while maintaining a width that does not exceed the outer link plates, thereby avoiding the manufacturing complexity and cost increases associated with wider inner plates.
2Reliability
If sleeve components are added to reduce friction and wear, then the chain performance improves, but the manufacturing effort and costs increase significantly
Solution Approach 1:
The patent extracts and eliminates the sleeve component from the chain design. By removing this additional component, the manufacturing effort and costs are significantly reduced. The design achieves acceptable wear resistance through the optimized plate thickness to link width ratio and proper lubrication, without requiring the complex sleeve assembly that would otherwise be needed to reduce friction and wear.
Solution Approach 2:
The patent adopts a simpler, more cost-effective approach by using the basic link plate structure with optimized dimensions rather than adding expensive sleeve components. The design accepts that the link plates will wear over time but compensates through the optimized geometry and lubrication, avoiding the high manufacturing costs associated with sleeve components while maintaining adequate service life.
3Strength
If the plate thickness is increased to absorb larger forces, then the fatigue strength improves, but the friction in the chain joint increases
Solution Approach 1:
The patent applies parameter changes by establishing an optimized relationship between plate thickness and link width (ratio greater than 1.6). This specific parameter combination allows the plate thickness to be increased sufficiently to absorb larger forces and improve fatigue strength, while the corresponding link width adjustment ensures that the friction in the chain joint remains within acceptable limits.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The sprocket chain (1) has inner chain links (2) and outer chain links (3), which are successive on top of each other in an alternating manner. The outer chain links comprise two outer plates (4), a middle plate (5) and two bolts (6). The middle plate is positioned between the inner plates (7). The inner plates have a plate thickness (d) and a web width in each case, where the ratio of plate thickness to web width is greater than 1.6.