Vehicle Control Device Torque Adjustment During Downshifts
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Solution Overview
Problem
During downshifts in a stepped automatic transmission mechanism, the decrease in vehicle front-rear acceleration is not properly suppressed due to inadequate torque increase, as the existing methods do not account for the varying downshift amounts of the through speed ratio.
Innovation Solution
A control device and method that adjust the torque input to the transmission by increasing the rotation speed of the torque increasing portion, such as the engine, in accordance with the downshift amount of the through speed ratio, ensuring a larger increase in torque during larger downshifts to mitigate the decrease in acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If torque is increased without considering the downshift amount of the through speed ratio, then the control is simplified, but the decrease in vehicle front-rear acceleration cannot be properly suppressed
Solution Approach 1:
The patent applies parameter changes by adjusting the torque increase amount based on the downshift amount of the through speed ratio. Specifically, when the downshift amount is large, a larger torque increase is applied, and when the downshift amount is small, a smaller torque increase is applied. This dynamic parameter adjustment resolves the contradiction by making the control effective across different downshift scenarios without requiring a completely complex control system.
Solution Approach 2:
The patent implements dynamics by making the torque increase amount variable rather than fixed. The control system dynamically determines the appropriate torque increase based on the actual downshift amount occurring during transmission shifts. This dynamic approach allows the system to adapt to different operating conditions while maintaining manageable control complexity.
2Ease of operation
If a fixed torque increase is applied during downshift, then the control is simple, but the torque is not properly increased for large downshift amounts resulting in inadequate acceleration suppression
Solution Approach 1:
The patent changes the torque increase parameter based on the downshift amount. Instead of applying a fixed torque increase, the system adjusts the torque increase magnitude to match the downshift severity. This resolves the contradiction by ensuring adequate power delivery during large downshifts while keeping the control implementation relatively simple through rule-based adjustment.
3Device complexity
If torque increase is not adjusted according to rotation speed increase amount, then the control is simpler, but the acceleration suppression is ineffective during large rotation speed increases
Solution Approach 1:
The patent implements parameter changes by linking the torque increase amount to the rotation speed increase amount of the torque increasing portion. When rotation speed increases significantly, the system applies a correspondingly larger torque increase. This relationship-based parameter adjustment maintains control logic simplicity while improving acceleration suppression reliability.
Data Source
AI summary
A vehicle includes a transmission having a variator and a sub-transmission mechanism, a controller serving as a shift control unit adapted to, as shift of the transmission, shift the sub-transmission mechanism and the variator so that a through speed ratio becomes a target speed ratio, and an engine serving as a torque increasing portion adapted to increase a torque inputted to the transmission in association with the shift of the transmission. The controller has a torque setting unit adapted to make a magnitude of an inclination larger as an increase amount of the engine rotation speed in association with the shift of the transmission is larger.