CVT Shift Control Apparatus Acceleration Intention
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Solution Overview
Problem
Existing shift control apparatuses for continuously variable transmissions (CVTs) often result in sudden, unpleasant downshifts when driver intention to accelerate is misinterpreted, leading to larger than necessary gear changes, causing discomfort for the driver.
Innovation Solution
A shift control apparatus that determines the driver's acceleration intention more accurately by using a mode determination map to differentiate between normal and acceleration modes, adjusting the target transmission ratio and shift speed based on the demanded degree of acceleration, thereby controlling downshifts to match the driver's intent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If switching to acceleration mode occurs immediately when accelerator opening and depression speed exceed threshold values, then vehicle acceleration response is improved, but sudden unpleasant feelings occur due to undesirably big downshifts when driver's acceleration intention is not strong
Solution Approach 1:
The patent changes the parameter of shift speed based on the determined degree of acceleration intention. When the demanded degree is small, the shift speed is reduced to prevent sudden unpleasant feelings, while when the demanded degree is large, the shift speed is maintained at the set value to ensure rapid acceleration response. This dynamic parameter adjustment resolves the contradiction between acceleration response and driver comfort.
Solution Approach 2:
The patent introduces dynamic adjustment of shift control parameters based on real-time determination of acceleration intention degree. The system transitions from a static threshold-based mode switching to a dynamic control approach where shift speed is continuously adjusted according to the driver's actual acceleration demand, making the system adaptive to varying driving conditions and intentions.
2Adaptability or versatility
If uniform shift line switching occurs when acceleration parameters exceed thresholds, then acceleration mode is activated, but target transmission ratio is undesirably set based on acceleration mode even when driver's acceleration intention is weak
Solution Approach 1:
The patent implements feedback by continuously monitoring accelerator operation parameters and determining the degree of acceleration intention based on this feedback. The system uses the determined degree to adjust shift control in real-time, creating a closed-loop control system that accurately reflects the driver's actual acceleration intention rather than relying solely on fixed threshold switching.
Solution Approach 2:
The patent segments the acceleration intention determination into different degrees (small vs. large demanded degree), allowing differentiated shift control strategies for different driving scenarios. This segmentation enables the system to distinguish between weak and strong acceleration intentions, applying appropriate shift speeds for each case rather than a uniform approach.
Data Source
AI summary
In a shift control apparatus of a continuously variable transmission (CVT) configured to steplessly vary a torque, the control apparatus employs an acceleration intention determination section for determining the presence or absence of a driver's acceleration intention, a shift mode setting section for setting a shift-control mode from a normal mode to an acceleration mode in the presence of the driver's acceleration intention, a shift speed setting section for setting a shift speed based on a target transmission ratio and a vehicle speed, and a shift control section for controlling a shift of the CVT. Also provided is a shift speed correction section for correcting the shift speed for an initial downshift in the acceleration mode to a shift speed slower than the shift speed set by the shift speed setting section, only when a demanded degree of the driver's acceleration intention is small.