CVT Control Device Thrust Force Ratio Feedback
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Solution Overview
Problem
Existing control devices for continuously variable transmissions in vehicles face challenges in maintaining fuel efficiency when hydraulic control accuracy is higher on one pulley side, leading to increased costs and potential belt slip issues due to oil pressure variations.
Innovation Solution
A control device that independently controls pulley pressures on both sides, prioritizing the side with higher hydraulic control accuracy to ensure belt slip prevention without adding oil pressure variations on the side with lower accuracy, using a hydraulic control circuit to calculate and adjust thrust forces based on actual gear ratios and torque inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hydraulic control accuracy is improved on one pulley side, then belt slip prevention is enhanced, but oil pressure variations cause thrust force deviations and potential belt slip on the other pulley side
Solution Approach 1:
The control device calculates the actual thrust force on the pulley side with lower hydraulic control accuracy by multiplying the thrust force on the other pulley side by a calculated thrust force ratio. This feedback mechanism compensates for oil pressure variations and ensures accurate thrust force control on both pulley sides, preventing belt slip while maintaining fuel efficiency.
Solution Approach 2:
The control device uses the thrust force ratio as an intermediary parameter to transfer control information between the two pulley sides. By calculating the thrust force ratio based on pulley effective diameters and controlling one pulley side's thrust force, the system indirectly controls the other pulley side's thrust force, ensuring synchronized and accurate thrust force management.
2Reliability
If oil pressure margins are increased on the pulley side with lower hydraulic control accuracy, then belt slip prevention is ensured, but fuel efficiency deteriorates
Solution Approach 1:
The control device continuously monitors and calculates the actual thrust force on the pulley side with lower hydraulic control accuracy using feedback from the other pulley side's thrust force and the calculated thrust force ratio. This real-time feedback enables precise thrust force control without requiring excessive oil pressure margins, thereby preventing belt slip while maintaining fuel efficiency.
3Device complexity
If thrust force control is centralized on one pulley side, then control complexity is reduced, but thrust force accuracy on the other pulley side deteriorates
Solution Approach 1:
The control device employs the thrust force ratio as an intermediary to distribute control accuracy from one pulley side to the other. By calculating this ratio based on pulley effective diameters and using it to determine the actual thrust force on the controlled pulley side, the system achieves accurate thrust force control on both sides while maintaining centralized control architecture.
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 ensures effective belt slip prevention and maintains fuel efficiency by minimizing oil pressure margins on the side with lower hydraulic control accuracy, allowing for precise thrust force management without increasing costs.
Implementation Method 1
a hydraulic control circuit capable of accurately controlling one of the input-side variable pulley and the output-side variable pulley in terms of thrust force
Implementation Method 2
a transmission belt wound around between the pair of the variable pulleys
Data Source
AI summary
A control device of a continuously variable transmission for a vehicle having a pair of variable pulleys with variable effective diameters of an input-side variable pulley and an output-side variable pulley and a transmission belt wound around between the pair of the variable pulleys, the continuously variable transmission respectively controlling an input-side thrust force in the input-side variable pulley and an output-side thrust force in the output-side variable pulley to set an actual gear ratio to a target gear ratio while preventing a slip of the transmission belt, the continuously variable transmission includes: a hydraulic control circuit capable of accurately controlling one of the input-side variable pulley and the output-side variable pulley in terms of thrust force as compared to the other, in the case that a target thrust force on the one side for assuring belt slip prevention of the both pulleys on the one side is set, based on a target thrust force on the one side, a target thrust force on the other side for achieving a target gear ratio on the other side being set, and a larger one being selected as the target thrust force on the one side out of a limit thrust force to a slip on the one side required for belt slip prevention on the one side, and a thrust force on the one side required for achieving a target gear ratio on the one side calculated based on a limit thrust force to a slip on the other side required for belt slip prevention on the other side.