Vehicle Downshift Control Using Oil Pressure and MG2 Torque
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Solution Overview
Problem
In automatic driving mode, vehicles experience prolonged shift times and uncomfortable acceleration shocks due to reduced drive torque during transmission downshifts, leading to a strange or uncomfortable feeling for the driver.
Innovation Solution
A control system that increases oil pressure to engagement devices during downshifts in automatic driving mode, while also enhancing drive-side torque from rotating machines, to reduce acceleration retraction and maintain shift time consistency with manual driving mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the shift time of the transmission is increased during traveling in the automatic driving mode, then shift shock is reduced, but acceleration is reduced and retraction of acceleration appears due to a drop of drive torque during a downshift
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the oil pressure supplied to engagement devices during downshift operations. Specifically, the control system increases oil pressure to the release-side engagement device during the inertia phase of downshift in automatic driving mode, which modifies the shift characteristics to reduce acceleration retraction while maintaining shift shock reduction benefits
Solution Approach 2:
The patent implements dynamics by making the oil pressure control adaptive based on driving mode and shift phase. The system dynamically changes oil pressure levels during different stages of the downshift process (particularly during the inertia phase), allowing the transmission to optimize both comfort (shift shock) and performance (acceleration) characteristics in real-time
2Stability of the object's composition
If the shift time of the transmission is increased during traveling in the automatic driving mode, then shift shock is reduced, but the driver feels strange or uncomfortable due to prolonged retraction of acceleration
Solution Approach 1:
The patent modifies the oil pressure parameter during the inertia phase of downshift to optimize driver comfort. By increasing oil pressure to the release-side engagement device during this specific phase, the system reduces the magnitude and duration of acceleration retraction, thereby eliminating the strange or uncomfortable feeling while preserving the shift shock reduction effect
Solution Approach 2:
The patent applies the skipping principle by reducing the duration of the inertia phase through optimized oil pressure control. By accelerating the engagement process through controlled pressure increases, the system rushes through the problematic phase of acceleration retraction more quickly, minimizing the time the driver experiences uncomfortable sensations
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 approach reduces the duration and impact of acceleration retraction, minimizing shift time prolongation and driver discomfort by maintaining torque levels and shift speed equivalence with manual driving mode.
Implementation Method 1
an oil pressure of hydraulic oil supplied to one of engagement devices to be released during a downshift of the transmission while the vehicle is traveling in the automatic driving mode is made higher than that set during traveling in the manual driving mode
Data Source
AI summary
While a vehicle is traveling in an automatic driving mode, an auto-driving oil pressure changing unit makes the engagement pressure of hydraulic oil supplied to a release-side engagement device to be released during a downshift of a stepwise shifting unit, higher than the engagement pressure set during traveling in a manual driving mode, so that retraction of the acceleration due to a drop of drive torque during the downshift is reduced. At this time, an auto-driving rotating machine controller makes drive-side MG2 torque generated from a second rotating machine, larger than that generated during traveling in the manual driving mode, so as to speed up the progress of the downshift, and prevent retraction of the acceleration from being prolonged.