CVT Control Apparatus Dynamic Mode Switching
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Solution Overview
Problem
Conventional control apparatuses for continuously variable transmissions lack the ability to dynamically adjust the transmission mode and ratio to effectively respond to driver preferences for acceleration performance and fuel efficiency, leading to suboptimal engine rotation speed control and transmission feel.
Innovation Solution
A control apparatus that includes a driving condition parameter detector, engine rotation speed detector, drive feeling setting device, predetermined rotation speed setter, transmission mode selector, and transmission ratio controller, allowing for seamless switching between continuous and stepped transmission modes based on detected conditions and driver-set preferences, adjusting the transmission ratio to maintain optimal engine speed and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transmission mode is switched between continuous and stepped transmission modes, then the acceleration performance and fuel efficiency are improved, but the device complexity increases due to multiple control modes and switching logic
Solution Approach 1:
The control system dynamically switches between continuous transmission mode and stepped transmission mode based on driving conditions. The transmission ratio control is adapted in real-time: in continuous mode, the ratio changes smoothly; in stepped mode, the ratio changes in discrete steps. This dynamic adaptation allows the system to optimize acceleration performance while managing complexity through condition-based mode selection rather than a permanently complex control structure.
2Use of energy by moving object
If the transmission ratio is controlled to maintain optimal engine rotation speed, then the fuel efficiency is improved, but the responsiveness to driver input may be reduced
Solution Approach 1:
The system dynamically adjusts the transmission ratio control strategy based on the selected transmission mode. In continuous transmission mode, the ratio is controlled to maintain optimal engine speed for fuel efficiency. In stepped transmission mode, the ratio is controlled in discrete steps that can provide more immediate response to driver input. The control system switches between these dynamic behaviors based on driving conditions, thereby balancing fuel efficiency and responsiveness.
Solution Approach 2:
The control system changes the transmission ratio parameter differently depending on the operating mode. In continuous mode, the ratio parameter changes continuously to optimize engine speed and fuel consumption. In stepped mode, the ratio parameter changes in discrete steps that can provide more noticeable acceleration response. This parameter change strategy allows the system to optimize fuel efficiency when needed while providing responsive acceleration when required.
3Measurement precision
If the transmission mode switching is based on engine rotation speed and throttle valve opening change amount, then the control precision is improved, but the loss of time occurs during mode transition
Solution Approach 1:
The control system uses preliminary thresholds and conditions to determine when mode switching should occur. By monitoring engine rotation speed and throttle valve opening change amount continuously and comparing them against predetermined thresholds, the system can anticipate optimal switching points before they are critically needed. This preliminary detection and decision-making reduces the actual transition time by having the switching logic ready to execute immediately when conditions are met.
Data Source
AI summary
A control apparatus for a continuously variable transmission is capable of continuously changing an output of an internal combustion engine mounted on a vehicle and allowing a transmission mode to be switchable between a continuous transmission mode in which a transmission ratio is set continuously and a stepped transmission mode in which the transmission ratio is set stepwise. A transmission mode selector is configured to change the transmission mode in such a manner that in a case where the stepped transmission mode is selected, when a engine rotation speed reaches a first predetermined rotation speed, then falls below a second predetermined rotation speed which is lower than the first predetermined rotation speed, and further falls below a third predetermined rotation speed, the transmission mode is switched from the stepped transmission mode to the continuous transmission mode.