Integrated CVT Launch Clutch and Sheave for Slip Control
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Solution Overview
Problem
Current continuously variable transmissions (CVTs) with steel belts require constant tension and infinite gear ratios during vehicle launch, leading to frictional losses and the need for additional components like torque converters or clutches to manage slip.
Innovation Solution
An integrated hydraulic system for a CVT that controls both the launch clutch and drive sheave, using a hydraulically actuated clutch pack and piston to selectively couple engine torque and adjust the movable sheave member, eliminating the need for dedicated launch devices and torque converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluid based torque converter is used to address slip during vehicle launch, then slip is managed, but device complexity increases
Solution Approach 1:
The patent combines the launch clutch and drive sheave into a single integrated assembly, where the clutch is positioned within the drive sheave structure. This merging eliminates the need for a separate torque converter while maintaining slip management capability through the clutch mechanism during launch conditions.
Solution Approach 2:
The integrated launch clutch and drive sheave performs multiple functions: it acts as both a clutch mechanism for managing slip during launch and as a drive sheave for continuous variable transmission operation. This multi-functionality replaces the need for separate torque converter and clutch components.
2Ease of operation
If a separate hydraulic control system is used for the launch clutch, then clutch control is achieved, but device complexity increases
Solution Approach 1:
The hydraulic system is designed to serve dual purposes: it provides hydraulic pressure for both the launch clutch actuation and the drive sheave operation. This shared hydraulic control system eliminates the need for separate control systems while maintaining independent control capability for both components.
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 solution simplifies the system design, reduces costs, and ensures efficient torque transmission by eliminating the need for separate hydraulic control valves and torque converters, while maintaining compact packaging and minimizing frictional losses.
Implementation Method 1
The integrated hydraulic system providing hydraulic communication between the launch clutch and drive sheave, the hydraulic system configured to both activate the launch clutch to selectively couple engine torque between the motor and the drive sheave and to axially move the movable sheave member on the drive sheave post
Data Source
AI summary
An integrated launch clutch and drive sheave for a continuously variable transmission (CVT) is provided. The integrated launch clutch and drive sheave includes a drive sheave, a launch clutch and an integrated hydraulic system. The drive sheave includes a fixed sheave member that is statically mounted on and rotationally fixed to a drive sheave post and a movable sheave member that is slidably mounted on the drive sheave post. The launch clutch is in rotational communication with a motor. The launch clutch is configured to selectively couple engine torque from the motor to the drive sheave post of the drive sheave. The integrated hydraulic system is configured to both activate the launch clutch to selectively couple engine torque between the motor and the drive sheave and to axially move the movable sheave member on the drive sheave post of the drive sheave in relation to the fixed sheave member.