Continuously Variable Transmission Segmented Pulley Design
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Solution Overview
Problem
Conventional continuously variable transmissions face challenges in achieving a wide range of transmission ratios while maintaining high belt transmitting efficiency and low ring damage without increasing the weight of the transmission, as larger pulley diameters and shaft distances lead to increased weight and reduced efficiency.
Innovation Solution
The design incorporates a configuration with a first rotational mechanism having a smaller outer diameter than a second rotational mechanism, allowing for a narrowed transmission ratio range and efficient power transmission, with the ability to switch the drive/driven relation between the mechanisms to achieve a wider overall transmission ratio range without weight increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If outer diameters and shaft distance of the pulley unit are extended to achieve a wide transmission ratio range, then the transmission ratio range is improved, but the weight of the transmission increases due to weight increment of the pulley and belt
Solution Approach 1:
The transmission system is divided into two separate pulley units: a first pulley unit with a first belt and a second pulley unit with a second belt. Each pulley unit operates independently with its own belt, allowing the transmission ratio range to be extended without proportionally increasing the weight of a single belt-pulley system. This segmentation enables the system to achieve a wide overall transmission ratio range while keeping individual component weights manageable.
Solution Approach 2:
The patent combines two pulley units with different transmission ratio ranges into a single transmission system. The first pulley unit and second pulley unit work together, with their transmission ratio ranges being merged to create an extended overall transmission ratio range. This merging allows the system to achieve a wider total ratio range than either unit could provide alone, while the weight increase is distributed across two separate, optimized units rather than one oversized unit.
2Adaptability or versatility
If outer diameters and shaft distance of the pulley unit are extended to achieve a wide transmission ratio range, then the transmission ratio range is improved, but the belt transmitting efficiency deteriorates and ring damage increases
Solution Approach 1:
The transmission system is divided into two separate pulley units, each operating within its own optimized transmission ratio range. The first pulley unit handles specific ratio ranges while the second pulley unit handles other ranges, allowing each unit to maintain high belt transmitting efficiency within its operational domain. This segmentation prevents any single belt from operating continuously at extreme ratio ends where efficiency deteriorates.
Solution Approach 2:
The system dynamically switches between the first and second pulley units depending on the required transmission ratio. By selecting which pulley unit to operate based on the current ratio requirement, the system ensures that the active pulley unit always operates within its efficient transmission ratio range, thereby maintaining high belt transmitting efficiency across the entire extended transmission ratio range.
3Adaptability or versatility
If outer diameters and shaft distance of the pulley unit are extended, then the transmission ratio range is improved, but the fuel consumption rate deteriorates due to increased operation frequency in high load range
Solution Approach 1:
The transmission system is divided into two separate pulley units, each optimized for specific transmission ratio ranges. This segmentation allows the system to operate each unit within its efficient range, reducing the frequency of high-load operations on any single belt-pulley system. Consequently, the overall fuel consumption is reduced compared to a single extended pulley unit that would operate continuously at inefficient ratio ends.
4Adaptability or versatility
If outer diameters and shaft distance of the pulley unit are extended, then the transmission ratio range is improved, but the endurance of the belt is lowered due to increased operation frequency in high load range
Solution Approach 1:
The transmission system is divided into two separate pulley units with separate belts, each operating within optimized transmission ratio ranges. This segmentation distributes the operational load across two belts rather than one, reducing the cumulative high-load operation frequency on each individual belt. As a result, the endurance and service life of each belt is extended compared to a single belt system operating across the entire extended ratio range.
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 configuration ensures high belt transmitting efficiency and reduced ring damage, improving fuel consumption and extending the life of the power transmitting means while maintaining a lightweight transmission.
Implementation Method 1
a V-belt that transmits a drive torque between the first and second pulleys
Data Source
AI summary
A continuously variable transmission is configured wherein an outer diameter of a first pulley 11 is smaller than an outer diameter of a second pulley 12, a first input shaft 1′ and a second input shaft 2′ have a parallel coaxial structure, the first input shaft 1′ and a first output shaft 14 are linked via a LO clutch 3″ and a first transmission gear assembly 8; and the second input shaft 2′ and a second output shaft 15 are linked via a HI clutch 3′ and a second transmission gear assembly 9. In-low-speed mode, a drive torque outputted from the second pulley 12 is transmitted to a differential via the second transmission gear assembly, a second low-speed gear 23, and a low final gear 16, whereas in high-speed mode, a drive torque outputted from the first pulley is transmitted to the differential via a high final gear 18.