Vehicle Transmission Control Device Torque Down Timing
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Solution Overview
Problem
Existing control devices for vehicle transmission systems experience residual pressure issues in engagement devices during upshift control, leading to unnatural torque feelings for drivers due to delayed pressure reductions and resulting negative torque transfer to wheels.
Innovation Solution
An electronic control unit is implemented to adjust the start timing and reduction speed of torque down control based on pre-transmission shift torque, along with temporary engagement pressure increases, to manage residual pressure and torque transfer effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If torque down control is performed during upshift control, then the torque of the driving force source is reduced, but negative torque may be transferred to wheels via the release side engagement device due to residual pressure
Solution Approach 1:
The control device delays the start timing of torque down control relative to the execution timing of torque phase control. This preliminary adjustment ensures that torque reduction occurs only after the engagement pressure of the release side engagement device has sufficiently decreased, preventing negative torque transfer to the wheels while still achieving the desired torque reduction for smooth upshift execution.
Solution Approach 2:
The control device dynamically adjusts the start timing of torque down control based on the actual pressure reduction characteristics of the release side engagement device. By making the torque down control timing variable rather than fixed, the system adapts to residual pressure conditions and prevents harmful negative torque transfer while maintaining efficient upshift performance.
2Productivity
If the engagement pressure of the release side engagement device is reduced quickly, then the upshift control is completed faster, but residual pressure remains due to response delay causing torque transfer issues
Solution Approach 1:
The control device performs preliminary pressure reduction of the release side engagement device before initiating torque down control. This staged approach allows the engagement pressure to decrease in advance, eliminating residual pressure effects that would otherwise cause unreliable torque transfer, while maintaining overall fast upshift execution through coordinated timing of subsequent torque reduction.
Solution Approach 2:
The control device rushes through the pressure reduction phase of the release side engagement device before the torque reduction phase. By skipping ahead with pressure reduction while maintaining torque temporarily, the system ensures residual pressure is eliminated before torque down control begins, guaranteeing reliable torque transfer characteristics throughout the upshift process.
3Speed
If torque down control starts early, then the rotation change is achieved faster, but the driver may feel unnatural torque drop when residual pressure is present
Solution Approach 1:
The control device performs preliminary pressure reduction of the release side engagement device before initiating torque down control. This ensures that when torque reduction begins, no residual pressure remains to cause unnatural torque drops, thereby maintaining driver comfort while still achieving fast rotation change through efficient coordinated control of pressure and torque reduction.
Data Source
AI summary
A control device for controlling a vehicle driving device provided with a transmission apparatus including a plurality of engagement devices in a power transmission path between a driving force source and a wheel and selectively forming a plurality of transmission shift stages having different transmission shift ratios depending on engagement states of the plurality of engagement devices.