Transverse Segment Recess for CVT Lubricant Flow
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Solution Overview
Problem
The existing design of transverse segments in drive belts for continuously variable transmissions hampers the flow of lubricant to the ring stack, leading to high friction and wear due to the obstructive nature of the rocking edges and pillar parts, which restricts the lubricant's access to the slipping contact between the rings.
Innovation Solution
A recessed area is introduced on the base part of the transverse segment, extending radially inward from the boundary surface and along the full axial width, with a reduced thickness that smoothly merges with other parts to facilitate lubricant flow from the radial inside to the ring stack, while maintaining structural integrity and minimizing fatigue strength impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transverse segment has a standard design with pillar parts and rocking edges, then the structural integrity and containment of ring stack is improved, but the flow of lubricant to the ring stack is hindered
Solution Approach 1:
The base part is segmented into different functional zones: a first region with standard thickness for structural support, and a second recessed region with reduced thickness for lubricant flow. This segmentation allows the structure to simultaneously maintain integrity and facilitate lubrication.
Solution Approach 2:
The thickness of the base part is varied locally: the first region maintains standard thickness for strength, while the second region has reduced thickness to create a recessed area that channels lubricant flow to the ring stack contact surfaces.
2Reliability
If the transverse segment has a standard design with pillar parts, then the containment of ring stack is improved, but the access of lubricant to the slipping contact is restricted
Solution Approach 1:
The recessed area acts as an intermediary channel that guides lubricant from the radial inside of the drive belt to the slipping contact between rings. This intermediate structure facilitates lubricant access without compromising the containment function of the pillar parts.
3Productivity
If the recessed area is introduced with reduced thickness, then the lubricant flow is improved, but the fatigue strength may be impacted
Solution Approach 1:
The thickness parameter of the base part is changed locally in the second region to create a recessed area. This parameter change optimizes lubricant flow while the gradual merging with the first region minimizes stress concentration, protecting against fatigue.
Solution Approach 2:
Instead of adding material to improve lubricant flow (which would harm fatigue strength), the design removes material to create a recessed area. This inverted approach—subtracting rather than adding—achieves better lubrication while preserving structural integrity.
4Volume of moving object
If the transition section has sharp curvature, then the compactness of drive belt design is improved, but the gap between ring stack and transition section increases
Solution Approach 1:
The solution moves from modifying the transition section curvature (one dimension) to modifying the base part thickness in the radial direction (another dimension). By creating a recessed area through thickness variation, the design achieves better lubricant flow and reduced wear while maintaining the sharp curvature for compactness.
Data Source
Figure 1~3
Figure 4~6
AI summary
The invention concerns a transverse segment (1) for a drive belt for a continuously variable transmission with a ring stack and with a number of transverse segments (1) attached along the circumference of the ring stack. The transverse segment (1) defines a central recess (5) that is bound by a boundary surface (13) of a base part (10) of the transverse segment (1). According to the invention, the base part (10) of the transverse segment (1) is provided with a recessed area (18) of locally reduced thickness extending from the boundary surface (13) downwards in height direction, which recessed area (18) provides a channel for lubricant to flow outwards in radial direction between abutting transverse segments (1) in a curved section of the drive belt (50) during operation in the transmission.