Toothed Chain with Enlarged External Flank Angle
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Solution Overview
Problem
Existing toothed chains in timing chain drives of automobile engines face limitations in durability and load capacity, leading to the need for improved service life without increasing costs, as slight performance enhancements can necessitate complete chain drive redesigns.
Innovation Solution
A toothed chain design with an external flank angle of 65° to 75° and a pitch-to-joint pin diameter ratio of ≤2.65, allowing for a more stable chain wheel engagement and enlarged joint surfaces, enabling reduced chain wheel teeth and improved service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the external flank angle is increased from 60° to 65°-75° and the pitch-to-joint pin diameter ratio is reduced to ≤2.65, then the service life and stability of the toothed chain are improved, but the dimensions of the joint pins and chain structure are constrained
Solution Approach 1:
The patent applies parameter changes by optimizing the external flank angle from the conventional 60° to a range of 65°-75°, and by setting the pitch-to-joint pin diameter ratio (VBa) to ≤2.65. These parameter modifications directly improve the service life and stability of the toothed chain while maintaining compatibility with standard chain wheel designs.
2Reliability
If the joint pin outer diameter is increased to enlarge the joint surface, then the service life is improved, but the ratio VBa increases beyond the optimal range
Solution Approach 1:
The patent establishes an optimal balance by defining the pitch-to-joint pin diameter ratio (VBa) should be ≤2.65. This parameter constraint ensures that the joint pin diameter is sufficiently large to provide an enlarged joint surface for improved service life, while maintaining the ratio within manufacturing tolerances and design specifications.
Data Source
AI summary
The invention is related to a toothed chain with alternating inner and outer chain links each joined by means of a chain joint, wherein the inner chain links comprise at least one inner plate and at least two joint bushes running perpendicularly through the same, the outer chain links comprise at least two outer plates and at least two joint pins running perpendicularly through the same, and to form a chain joint, one joint pin of the outer chain link each extends through a joint bush of the inner chain link, and at least one inner plate of the inner chain link and/or at least one outer plate of the outer chain link is embodied as a toothed plate with each two teeth defined by an outer flank and an inner flank each. To provide a toothed chain having an improved service life and which can lead to a more advantageous embodiment of the complete chain drive, it is provided that an external flank angle given for the two external flanks of a toothed plate, is α≧65° and ≦75°, and a ratio VBa between a pitch p of the toothed chain and the outer diameter dBa of the joint pins is ≦2.65.