Herringbone Spur Gear Axial Overlap for Quiet Transmission
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Solution Overview
Problem
Existing motor vehicle transmissions face challenges in achieving a compact and quiet design with high efficiency, as they often result in significant internal forces and noise due to the structural limitations of spur gears.
Innovation Solution
A spur gear with a herringbone toothing design is implemented, where the first and second gear bodies have helically toothed surfaces that overlap axially, ensuring continuous torque transmission by having the second tooth engage before the first tooth disengages, reducing axial extent and internal forces, and enhancing efficiency and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the axial extent of gear bodies is reduced to make the transmission compact, then the structural space requirement is minimized, but torque transmission continuity may be interrupted causing noise
Solution Approach 1:
The herringbone toothing design ensures continuous torque transmission by having the second tooth engage before the first tooth disengages. The overlapping axial arrangement of teeth from first and second gear bodies creates uninterrupted engagement, eliminating gaps in torque transmission that would otherwise cause noise and vibration.
Solution Approach 2:
The gear is divided into two separate gear bodies (first gear body with first teeth, second gear body with second teeth) that are axially offset. This segmentation allows each gear body to contribute teeth to the engagement process at different axial positions, ensuring continuous transmission while reducing the overall axial extent of each individual gear body.
2Device complexity
If conventional spur gear designs are used, then the structure is simple, but internal forces and noise are significant
Solution Approach 1:
The invention merges two helically toothed gear bodies into a single spur gear assembly with herringbone toothing. The first and second gear bodies are rotationally offset and axially arranged such that their teeth overlap, combining the benefits of helical gearing (continuous engagement, reduced shock loads) while maintaining the compact form factor of a spur gear.
3Volume of moving object
If the width of gear bodies is reduced to minimize axial space, then compactness is achieved, but tooth engagement continuity may be compromised
Solution Approach 1:
The solution transitions from considering only the width of individual gear bodies to utilizing the axial dimension for tooth overlap. By arranging teeth from first and second gear bodies at different axial positions with overlapping engagement zones, the design achieves continuous torque transmission without requiring excessive width in any single gear body.
Data Source
AI summary
A spur gear for transmitting a drive torque in a toothing of a motor vehicle transmission is provided, having a helically toothed first gear body for forming first teeth, a second gear body, which is helically toothed oppositely to the first gear body so as to form a herringbone toothing, for forming second teeth, wherein, on axial sides which face toward one another of the first gear body and of the second gear body, the first teeth and the second teeth point toward one another, so as to at least partially overlap one another, in each case pairwise, wherein, on that axial side of the first gear body which points toward the second gear body, a first tooth flank of the first tooth points in an axial direction toward a second tooth flank of a second tooth which follows the opposite second tooth in a circumferential direction.