CVT Drive Belt Segmentation for Lower Weight and Radial Alignment
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Solution Overview
Problem
The existing drive belts for continuously variable transmissions face challenges in minimizing weight while maintaining optimal operating performance, particularly in achieving line contact between transverse segments and pulley sheaves, which restricts further weight reduction.
Innovation Solution
The design incorporates two types of transverse segments with differing contact surface heights, where only some segments need to meet the minimum height requirements, allowing others with lower contact surfaces to be lighter and still maintain radial alignment through interaction with taller segments and the endless carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the height of contact surfaces of all transverse segments is increased to meet minimum height requirements, then radial alignment and line contact with pulley sheaves is improved, but the weight of the drive belt increases
Solution Approach 1:
The drive belt is divided into two types of transverse segments: first type segments with contact surfaces of greater height that provide radial alignment, and second type segments with contact surfaces of lesser height that reduce weight. This segmentation allows different parts of the system to have different functions - some segments provide structural support while others minimize mass.
Solution Approach 2:
Different transverse segments are assigned different contact surface heights based on their local functional requirements. First type segments have taller contact surfaces where radial alignment is critical, while second type segments have shorter contact surfaces where weight reduction is prioritized. This local differentiation optimizes the overall system by applying the minimum necessary height in each location.
2Weight of moving object
If the height of contact surfaces is reduced to minimize weight, then drive belt weight decreases, but line contact and radial alignment with pulley sheaves deteriorates
Solution Approach 1:
The drive belt is divided into two types of transverse segments: first type segments with contact surfaces of greater height that provide radial alignment, and second type segments with contact surfaces of lesser height that reduce weight. This segmentation allows different parts of the system to have different functions - some segments provide structural support while others minimize mass.
Solution Approach 2:
Different transverse segments are assigned different contact surface heights based on their local functional requirements. First type segments have taller contact surfaces where radial alignment is critical, while second type segments have shorter contact surfaces where weight reduction is prioritized. This local differentiation optimizes the overall system by applying the minimum necessary height in each location.
3Ease of manufacture
If all transverse segments are made with minimum height contact surfaces, then manufacturing simplicity is maintained, but the ability to prevent pitching and rolling rotations is insufficient
Solution Approach 1:
The drive belt is divided into two types of transverse segments: first type segments with contact surfaces of greater height that provide radial alignment, and second type segments with contact surfaces of lesser height that reduce weight. This segmentation allows different parts of the system to have different functions - some segments provide structural support while others minimize mass.
Solution Approach 2:
The first type transverse segments act as intermediary elements that provide the necessary radial alignment and stability. These taller segments serve as reference elements that prevent pitching and rolling rotations of the entire row of segments, while the second type segments benefit from this stabilization without requiring the same height.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the overall weight of the drive belt by minimizing the size of lighter segments while ensuring preferred radial alignment and preventing pitching and rolling rotations, thus maintaining effective torque transmission.
Implementation Method 1
The friction contact between the contact surfaces and the pulley sheaves allows a force to be transmitted there between, such that the drive belt can transfer a drive torque and rotational movement from one transmission pulley to the other
Data Source
Figure 1~2
Figure 3~7
AI summary
The invention relates to a drive belt (3) including an endless carrier (30) and a plurality of transverse segments (40; 40a, 40b) that are mounted on and arranged along the circumference of the carrier (30) in an essentially contiguous row. This type of drive belt (3) is well-known, in particular from its application in the friction-type belt-and- pulleys transmission. According to the invention, the efficiency of such a transmission can be improved by reducing the weight of the drive belt (3) by reducing the radial dimension of every other transverse segment (40; 40a, 40b) in the said row of transverse segments (40; 40a, 40b).