CVT Control Apparatus for Idling Pressure and Inertia Management
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Solution Overview
Problem
Existing vehicle transmission systems with continuously variable transmission (CVT) and gear mechanisms struggle to optimize fuel economy and power performance, particularly when the speed gear ratio of the CVT is shifted to higher gear ratios, leading to increased inertial losses and reduced line pressure, which can deteriorate vehicle drivability.
Innovation Solution
A control apparatus that includes an electronic control unit to manage hydraulic pressures applied to the pulleys, adjusting the winding radius of the belt to optimize the speed gear ratio of the CVT, ensuring that the line pressure is dominated by either the secondary or primary pressure, thereby reducing inertial losses and improving fuel economy and power performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the speed gear ratio of the idling continuously variable transmission mechanism is shifted to a higher speed gear ratio side, then the thrust of the output-side pulley is reduced and fuel economy is improved, but the equivalent inertia of the input rotating member increases and power performance deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the speed gear ratio of the idling continuously variable transmission mechanism based on operating conditions. The electronic control unit monitors line pressure dominance (secondary pressure vs. primary pressure vs. clutch pressure) and modifies the speed gear ratio parameter accordingly - shifting to higher gear ratios when secondary pressure dominates to reduce thrust and improve fuel economy, while maintaining lower gear ratios when clutch pressure dominates to minimize inertial effects and preserve power performance.
2Loss of energy
If the speed gear ratio of the idling continuously variable transmission mechanism is shifted to a higher speed gear ratio side, then the line pressure is reduced and driving force loss is suppressed, but the equivalent inertia of the input rotating member increases
Solution Approach 1:
The patent utilizes parameter changes by controlling the speed gear ratio as a dynamic variable that responds to pressure condition monitoring. The electronic control unit adjusts the speed gear ratio parameter to optimize the balance between line pressure reduction (for minimizing driving force loss) and equivalent inertia control (for maintaining power performance), thereby resolving the contradiction between energy loss reduction and device complexity management.
3Loss of energy
If the hydraulic pressure applied to the pulleys is reduced to improve fuel economy, then the thrust of the output-side pulley is reduced, but the belt may slip and power transmission reliability decreases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting hydraulic pressure parameters based on the dominance condition of different pressure sources. The electronic control unit monitors whether secondary pressure, primary pressure, or clutch pressure dominates the line pressure, and accordingly modifies the hydraulic pressure applied to the pulleys. This ensures that pressure is reduced only when it does not compromise belt grip, maintaining power transmission reliability while achieving fuel economy improvements.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the pressure conditions (secondary pressure, primary pressure, and clutch pressure dominance) and adjusting the hydraulic pressure and speed gear ratio accordingly. The electronic control unit uses this feedback information to determine the optimal operating point that balances fuel economy and power transmission reliability, preventing belt slip while minimizing energy loss.
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
The control apparatus effectively improves fuel economy by reducing hydraulic pressures when dominated by secondary or primary pressures, and minimizes inertial losses by controlling the CVT speed gear ratio towards the lowest gear ratio, enhancing vehicle power performance.
Implementation Method 1
a control apparatus that includes an electronic control unit to manage hydraulic pressures applied to the pulleys
Implementation Method 2
The belt is wound to span between the input-side pulley and the output-side pulley
Data Source
AI summary
When a line pressure is dominated (determined) by at least one of a primary pressure and a secondary pressure during idling of a continuously variable transmission, the hydraulic pressure that is applied to at least one of pulleys, to which the hydraulic pressure larger than a clutch pressure is applied, is reduced. On the other hand, when the line pressure is dominated by the clutch pressure during idling of the continuously variable transmission, the speed gear ratio of the continuously variable transmission is controlled to a lowest speed gear ratio.