CVT Pulley Thrust Control for Gear Ratio Stability
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Solution Overview
Problem
In vehicle drive-force transmitting apparatuses with continuously-variable transmission mechanisms, maintaining the highest gear ratio is challenging when detection accuracy of rotational speeds is insufficient, especially when input torque is low, leading to potential slippage and inefficient energy consumption.
Innovation Solution
A control apparatus that includes a detection-accuracy determining portion, a highest-gear-ratio determining portion, and a transmission-shifting control portion to adjust the thrust ratio between primary and secondary pulleys, ensuring the highest gear ratio is maintained without unnecessarily increasing secondary thrust, by calculating and setting thrust ratios based on the accuracy of rotational speed detection and input torque levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the primary thrust is reduced to prevent slippage and maintain highest gear ratio, then energy consumption is reduced, but the highest gear ratio cannot be maintained when input torque is low
Solution Approach 1:
The control apparatus dynamically adjusts the primary thrust parameter based on detected rotational speeds and input torque conditions. When detection accuracy is sufficient, the primary thrust is reduced to prevent slippage and lower energy consumption. When detection accuracy is insufficient, the primary thrust is increased to ensure the highest gear ratio is maintained, demonstrating parameter adaptation to changing operational conditions
Solution Approach 2:
The system continuously monitors rotational speeds of the primary and secondary pulleys, detects the actual gear ratio, and compares it with the target highest gear ratio. This feedback loop enables the control apparatus to determine when detection accuracy is sufficient or insufficient and adjust the primary thrust accordingly, ensuring reliable maintenance of the highest gear ratio while optimizing energy consumption
2Reliability
If the secondary thrust is increased to maintain highest gear ratio, then gear ratio stability is improved, but energy consumption increases unnecessarily
Solution Approach 1:
The control apparatus selectively adjusts only the primary thrust parameter while keeping the secondary thrust unchanged, when detection accuracy is insufficient and the actual gear ratio is already at the highest gear ratio. This targeted parameter adjustment maintains gear ratio stability without the unnecessary energy consumption that would result from increasing the secondary thrust
3Loss of energy
If the primary thrust is reduced below the minimum required value, then energy consumption is minimized, but the highest gear ratio cannot be maintained
Solution Approach 1:
The control apparatus dynamically adjusts the primary thrust parameter based on the sufficiency of detection accuracy. When detection accuracy is sufficient, the primary thrust is reduced to minimize energy consumption while maintaining gear ratio precision. When detection accuracy is insufficient, the primary thrust is increased to ensure the highest gear ratio is maintained, demonstrating adaptive parameter optimization
Solution Approach 2:
The system uses feedback from rotational speed detection to determine whether detection accuracy is sufficient. This feedback enables the control apparatus to adjust the primary thrust to an optimal value that maintains gear ratio precision while minimizing energy consumption, preventing reduction below the minimum required value
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
Effectively maintains the highest gear ratio without increasing secondary thrust unnecessarily, ensuring efficient energy use and preventing slippage even with insufficient detection accuracy of rotational speeds and low input torque.
Implementation Method 1
the primary pulley includes a primary hydraulic actuator configured to generate a primary thrust, based on which the transfer element is to be clamped by the primary pulley
Implementation Method 2
the secondary pulley includes a secondary hydraulic actuator configured to generate a secondary thrust, based on which the transfer element is to be clamped by the secondary pulley
Implementation Method 3
a continuously-variable transmission mechanism which is configured to transmit a drive force of the drive force source toward the drive wheels, and which includes a primary pulley, a secondary pulley, and a transfer element that is looped over the primary and secondary pulleys
Data Source
AI summary
A control apparatus for a drive-force transmitting apparatus that includes a transmission having primary and secondary pulleys. When a detection accuracy of rotational speed of the primary and secondary pulley is not assured, the control apparatus sets each of (i) a secondary-thrust calculation thrust ratio value used for calculation of a secondary thrust that is to be applied to the secondary pulley and (ii) a primary-thrust calculation thrust ratio value used for calculation of a primary thrust that is to be applied to the primary pulley, such that each of the secondary-thrust calculation thrust ratio value and the primary-thrust calculation thrust ratio value is dependent on a result of a determination as to whether an actual gear ratio of the transmission is the highest gear ratio and a result of a determination as to whether an input torque inputted to the transmission is lower than a given torque value.