CVT Drivetrain with Cascading Selection Mechanisms
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Solution Overview
Problem
The size requirements for a Continuously Variable Transmission (CVT) to cover the entire ratio range are often impractically large, making it difficult to integrate into vehicles effectively.
Innovation Solution
A drivetrain configuration that includes a CVT with first and second cascading selection mechanisms, controlled by a controller to adjust the position of the second selection mechanism based on desirable configurations, allowing for efficient gear ratio changes without the need for a large physical size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a CVT is designed to cover the entire ratio range, then the gear ratio coverage is improved, but the size of the transmission becomes impractically large
Solution Approach 1:
The transmission system is divided into two separate CVT units, each covering a portion of the total ratio range. The first CVT covers a first ratio range while the second CVT covers a second ratio range, with their combined ranges providing the full required coverage. This segmentation allows each unit to be compact while the system as a whole achieves extensive ratio coverage.
Solution Approach 2:
The patent employs cascading selection mechanisms where the second CVT can be selectively engaged or disengaged based on the required ratio. The selection mechanisms are arranged in a nested configuration where the second CVT operates in conjunction with or independently of the first CVT, allowing the system to achieve multiple ratio ranges without requiring all components to be simultaneously active, thus reducing overall size.
2Ease of operation
If the transmission size is reduced to fit vehicle constraints, then the ease of installation is improved, but the ability to cover the entire ratio range is worsened
Solution Approach 1:
By segmenting the transmission into two smaller CVT units with overlapping or complementary ratio ranges, each unit can be designed to fit within vehicle space constraints while the combination of both units provides the full required ratio coverage. The segmentation allows compact packaging while maintaining versatility.
Solution Approach 2:
The system uses dynamic selection mechanisms that can switch between different CVT configurations based on operating conditions. The controller selectively engages the first and second CVTs and their corresponding selection mechanisms to provide the appropriate ratio range for current vehicle needs, allowing a compact physical design to deliver extensive functional coverage.
Data Source
AI summary
A drivetrain for connection between the output of a prime mover and the input of a final drive is described herein. The drivetrain comprises a CVT including an input connected to the output of the prime mover and an output; a power mixer having a first input connected to the output of the prime mover, a second input coupled to the output disk of the CVT and an output; a three-speed transmission having an input connected to the output of the power mixer and an output connected to the input of the final drive.