ACC Shift Gear Limiting for Smoother Curve Driving
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Solution Overview
Problem
During Adaptive Cruise Control (ACC) driving in vehicles with step-type automatic transmissions, sudden gear shifts can impair the shift sensation, especially in curved sections or downhill roads with low resistance, leading to large changes in driving force.
Innovation Solution
A control apparatus that restricts the upper limit of the shift gear to 1 gear when entering a curve with a predetermined curvature, preventing rapid two-speed shifting and maintaining a stable shift sensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the vehicle upshifts to lower engine speed during curve driving, then fuel consumption is suppressed, but shift sensation is impaired due to large changes in driving force
Solution Approach 1:
The patent applies dynamics by making the transmission control adaptive to driving conditions. The control apparatus dynamically adjusts shift behavior based on detected curve information, steering angle, and vehicle speed. During curve driving, the system permits shifts that would normally be restricted, allowing the transmission to respond flexibly to changing conditions while maintaining smooth operation and good shift sensation.
Solution Approach 2:
The patent changes control parameters based on driving conditions. Specifically, it modifies the shift control logic by incorporating curve detection data, steering angle thresholds, and speed ranges. When curves are detected within specific angle ranges and speed thresholds are met, the system adjusts permissible shift gears and timing, thereby optimizing both fuel efficiency and shift sensation under varying operational parameters.
2Speed
If the vehicle downshifts to accelerate after passing through the curve, then vehicle speed increases, but shift sensation is impaired due to rapid two-speed shifting
Solution Approach 1:
The patent applies preliminary action by preparing for potential downshifts before they are strictly necessary. The control apparatus continuously monitors steering angle and vehicle speed, and when curve exit conditions are detected (steering angle within threshold and speed within range), it proactively manages transmission gear selection. This preliminary management of shift timing and gear selection prevents abrupt two-speed shifting while ensuring smooth acceleration after curve passage.
3Speed
If the automatic transmission shifts gears rapidly during ACC driving, then acceleration response is improved, but shift sensation deteriorates due to large torque changes
Solution Approach 1:
The patent applies feedback by using the detected curve information as input to the shift control decision-making process. The control apparatus receives feedback from curve detection means, steering angle sensors, and speed sensors, then uses this feedback to determine appropriate shift behavior. This closed-loop control ensures that shifts occur at optimal moments, balancing acceleration response with smooth shift sensation by preventing shifts during critical curve sections.
Data Source
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AI summary
[Problem to be Solved] To improve a shift feeling in a curved section during ACC driving in a vehicle including a step-type automatic transmission. [Solution] In a control apparatus for a vehicle which includes a step-type automatic transmission and has an ACC function for causing a vehicle to run at a set vehicle speed when no vehicle ahead is present in a driving lane of the vehicle, and making an acceleration request/deceleration request for causing the vehicle to run while following a vehicle ahead with maintaining a set inter-vehicular time with respect to the vehicle ahead when the vehicle ahead is present in the driving lane of the vehicle, and a curve driving assist function for making a deceleration request when entry into a curve having a predetermined curvature or greater is detected and a curve driving condition is satisfied, the control apparatus is configured so as to restrict an upper limit of a shift gear of the automatic transmission to 1 gear if the curve driving condition is satisfied during running based on the ACC function.