Vehicle Shift Control for Kickdown Responsiveness
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Solution Overview
Problem
Neutral coasting control in vehicles improves fuel economy but results in low acceleration responsiveness, especially when kickdown is used, due to the need for transmission downshift from a neutral state to a drive state, which increases shift time and reduces responsiveness.
Innovation Solution
A shift control apparatus and method that corrects oil pressure and control duty for clutch release during kickdown shifts, reducing shift time and preventing faulty learning by determining driver input patterns and adjusting oil pressure and control duties accordingly, including lowering oil pressure and control duty levels during kickdown shifts and prohibiting learning during coasting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If neutral coasting control is implemented to improve fuel economy, then fuel economy is improved, but acceleration responsiveness deteriorates due to transmission shift time
Solution Approach 1:
The clutch is pre-released before the kickdown shift occurs during neutral coasting control. By releasing the clutch in advance (when the transmission is still in neutral state), the transmission input shaft can rotate freely and synchronize speeds more quickly, eliminating the delay that would normally occur during the transition from neutral to drive state. This preliminary action resolves the contradiction by preparing the system ahead of time for the upcoming shift, thus improving acceleration responsiveness without sacrificing fuel economy benefits.
2Speed
If transmission shifts from neutral state to drive state during kickdown, then acceleration is achieved, but shift time increases and responsiveness is reduced
Solution Approach 1:
The clutch release operation is performed in advance before the kickdown shift command is executed. When the transmission is in neutral state, the clutch is released so that the input shaft is already rotating and synchronized with the turbine speed. This eliminates the time required for clutch engagement and shaft synchronization during the actual kickdown shift, thereby reducing shift time and improving acceleration responsiveness.
Solution Approach 2:
The control system dynamically adjusts clutch control based on the operational state. During neutral coasting control, the clutch control is modified to be released earlier than normal, creating a dynamic adaptation to the specific operating conditions. This dynamic control strategy allows the system to optimize shift timing and reduce shift duration while maintaining fuel economy benefits.
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
This solution improves acceleration responsiveness by reducing shift time during kickdown events and preventing faulty learning, enhancing the vehicle's ability to quickly respond to driver inputs and maintain efficient fuel economy.
Implementation Method 1
corrects an oil pressure for release of a clutch in the transmission at the time of a kickdown shift
Data Source
AI summary
An apparatus for shift control in a vehicle includes: a transmission; an acceleration apparatus; and a control circuit electrically connected with the transmission and the acceleration apparatus. The control circuit shifts the transmission from a drive state to a neutral state when an activation condition for coasting is satisfied during travel of the vehicle, and corrects an oil pressure for release of a clutch in the transmission at the time of a kickdown shift, when a driver's input for kickdown is detected through the acceleration apparatus during the coasting.