Vehicle Downshift Torque Control for Faster Shifts With Less Shock
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Solution Overview
Problem
Existing vehicle control systems experience prolonged shift times and mechanical shocks during downshifting when the accelerator is depressed during an accelerator-off state, leading to poor driving response and potential mechanical issues.
Innovation Solution
A control device that adjusts engine torque by varying throttle torque request amounts before and after the inertia phase of automatic transmission downshifting, using a retard angle to delay ignition timing and gradually increasing throttle torque demand to minimize mechanical shocks and shorten shift times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If torque is increased based on electronic control throttle operation during downshifting when accelerator is depressed, then driving response is improved, but mechanical shocks may occur
Solution Approach 1:
The control device performs preliminary determination of downshifting occurrence before the actual shift begins. By detecting accelerator depression state and predicting downshift timing, the system prepares torque control parameters in advance, enabling smooth torque transition that prevents mechanical shocks while maintaining rapid driving response.
Solution Approach 2:
The control device dynamically adjusts torque control parameters based on real-time detection of accelerator depression state and downshift phase. The torque increase is modulated according to the specific moment in the downshifting process, creating a dynamic control strategy that balances rapid response with shock prevention.
2Productivity
If throttle torque request amount is increased before inertia phase to shorten shift time, then productivity is improved, but mechanical shocks and misfires may occur
Solution Approach 1:
The control device sets the first throttle torque request amount before the inertia phase begins, preparing the engine for upcoming torque demands. This preliminary torque preparation enables faster shift execution while the controlled, gradual increase prevents mechanical shocks and engine misfires by avoiding sudden torque spikes.
Solution Approach 2:
The control device applies a controlled excessive torque request (first throttle torque request amount) before the inertia phase to ensure the shift completes within the available time window. This partial excessive action guarantees shift productivity while the subsequent second throttle torque request amount controls the actual torque delivery to prevent harmful effects.
3Loss of energy
If downshifting is performed during accelerator-off state, then energy efficiency is improved, but driving response deteriorates when accelerator is subsequently depressed
Solution Approach 1:
The control device detects accelerator depression during downshifting and performs preliminary torque preparation by setting appropriate throttle torque request amounts before the inertia phase. This ensures that when the driver demands power during coasting, the engine responds rapidly without the lag that would normally occur during gear changes.
Solution Approach 2:
The control device dynamically switches control strategies based on accelerator state. During accelerator-off downshifting, it maintains energy efficiency, but upon detecting accelerator depression, it transitions to a dynamic torque control mode that prioritizes driving response by increasing throttle torque request amounts at critical moments.
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
The control device reduces shift times and improves driving comfort by smoothly increasing engine torque without causing mechanical shocks or misfires, enhancing the vehicle's response and reducing gear change duration.
Implementation Method 1
controls torque by the operation of an electronic control throttle 13 of the engine 10
Implementation Method 2
a retard angle for retarding an ignition timing of the engine 10 is generated in the first period
Data Source
AI summary
ECU of the motor vehicle controls the driving condition of the engine and the shift stage of the automatic transmission. ECU controls a determination step of determining whether a downshift occurs in the accelerator-on state during the downshift associated with the accelerator-off, and a torque-up step of increasing the torque based on the operation of the electronic control throttle of the engine when the downshift occurs in the accelerator-on state. In the torque-up step, the first throttle torque request amount in the first period before the start of the inertia phase is made smaller than the second throttle torque request amount in the second period after the start of the inertia phase.