CVT Shift Control Using Pseudo Accelerator Signal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional shift control apparatuses for continuously variable transmissions cause unnatural driving feelings when driving uphill due to linear upshift and downshift operations, leading to slippage and engine noise issues.
Innovation Solution
A shift control apparatus that includes a target transmission gear ratio setting section, a shift control section, an uphill judging section, and a pseudo accelerator opening degree generating section, which adjusts the target gear ratio based on actual and pseudo accelerator opening degrees to manage shifts more smoothly during uphill driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the continuously variable transmission performs upshift and downshift linearly in accordance with accelerator operation, then the transmission can rapidly attain the appropriate transmission gear ratio, but the driver experiences unnatural driving feelings and slippage feeling during uphill driving
Solution Approach 1:
The patent applies dynamics by making the shift control characteristics changeable based on driving conditions. The control apparatus dynamically adjusts shift control parameters including upper and lower limit rotational speeds of the primary pulley, and upshift/downshift control characteristics, depending on whether the vehicle is driving uphill or on level ground, thereby optimizing both response speed and comfort for different conditions
Solution Approach 2:
The patent changes control parameters based on detected driving conditions. When uphill driving is detected, the control apparatus modifies parameters such as the upper limit rotational speed of the primary pulley during downshift, and the control characteristics of upshift/downshift operations, to prevent unnatural driving feelings while maintaining rapid shift response
2Ease of operation
If the upshift is restricted to prevent unnatural driving feelings, then the driver experiences more natural shift behavior, but the transmission cannot rapidly attain the target gear ratio
Solution Approach 1:
The control apparatus dynamically adjusts shift control characteristics based on detected driving conditions. When uphill driving is detected, it applies relaxed control characteristics that allow faster shifts; when level ground driving is detected, it applies restricted control characteristics that prioritize comfort, thereby optimizing both speed and comfort for different conditions
Solution Approach 2:
The patent changes control parameters including upper and lower limit rotational speeds of the primary pulley, and upshift/downshift control characteristics, based on detected driving conditions. This allows the system to execute shifts rapidly when needed while preventing unnatural driving feelings during normal driving
3Adaptability or versatility
If the accelerator opening degree is frequently changed during uphill driving, then the transmission can respond to driver input, but the shift behavior becomes unnatural and causes engine noise
Solution Approach 1:
The control apparatus performs preliminary action by detecting uphill driving conditions in advance and proactively setting appropriate control characteristics before problematic accelerator operations occur. When uphill driving is detected, it pre-configures the control parameters to handle accelerator opening changes smoothly, preventing unnatural shift behavior and engine noise before they occur
Solution Approach 2:
The patent changes control parameters including upper and lower limit rotational speeds of the primary pulley, and upshift/downshift control characteristics, based on detected driving conditions. This allows the system to respond to accelerator operations adaptively while preventing harmful effects like engine noise and slippage
Data Source
AI summary
A shift control apparatus for continuously variable transmission includes: a pseudo accelerator opening degree generating section configured to generate a pseudo accelerator opening degree larger than the actual accelerator opening degree when the actual accelerator opening degree is decreased when the judging section judges that the vehicle runs the uphill; the target transmission gear ratio setting section being configured to set the target transmission gear ratio by the pseudo accelerator opening degree when the pseudo accelerator opening degree is inputted, and the shift control section being configured to control the shift toward the target transmission gear ratio set based on the pseudo accelerator opening degree and the vehicle speed when the pseudo accelerator opening degree is generated, and to control the shift toward the target transmission gear ratio set based on the actual accelerator opening degree and the vehicle speed when the pseudo accelerator opening degree is not generated.