Vehicle Control Apparatus Torque Management for Shift Synchronization
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Solution Overview
Problem
The existing control apparatus for vehicles with electric motors and step-variable transmissions experiences delays in generating reverse drive force when switching from forward to reverse gear during coasting, leading to inefficient shift-down actions and potential failure in progressing the transmission.
Innovation Solution
The control apparatus temporarily increases the forward drive torque of the electric motor to raise the input speed of the step-variable transmission, and then engages the coupling device to ensure it reaches the synchronizing speed, while limiting the reverse drive torque until the coupling device is fully engaged, thereby facilitating smooth gear shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reverse drive torque of the electric motor is generated during a shift-down action of the step-variable transmission to the forward-drive low-speed position in a coasting run, then the shift-down action is interrupted and the reverse vehicle drive force is delayed, but if the forward drive torque is maintained to complete the shift-down action, then the reverse drive force generation is further delayed
Solution Approach 1:
The control apparatus increases the forward drive torque above the required value before the shift-down action is completed, preliminarily preparing the input speed to reach the synchronizing speed. This preliminary torque increase ensures the shift-down action can be completed successfully even when reverse drive torque is subsequently generated, preventing shift interruption while minimizing reverse drive force delay.
Solution Approach 2:
The control apparatus dynamically adjusts the electric motor torque based on the shift-down progress and reverse drive torque generation. It temporarily increases forward drive torque during the shift-down action, then transitions to reverse drive torque generation, creating a dynamic torque profile that balances shift completion reliability with reverse drive force generation speed.
2Reliability
If the input speed of the step-variable transmission is raised to the synchronizing speed before engagement, then the shift-down action progresses smoothly, but the time required for reverse drive force generation increases
Solution Approach 1:
The control apparatus changes the torque parameter dynamically during the shift-down action. It increases the forward drive torque above the required value to raise the input speed to the synchronizing speed, ensuring smooth shift-down action. After the shift-down is completed, it transitions to generating reverse drive torque, optimizing both shift smoothness and reverse drive force generation time through parameter adjustment.
3Productivity
If the engaging force of the coupling device is increased to complete the shift-down action during coasting, then the shift-down progresses despite reverse drive torque, but transmission reliability may be compromised
Solution Approach 1:
The control apparatus applies preliminary anti-action by increasing the forward drive torque above the required value before the reverse drive torque interrupts the shift-down action. This preliminary torque increase creates a buffer that allows the shift-down action to progress even when reverse drive torque is generated, maintaining both shift progress and transmission reliability.
Data Source
AI summary
A control apparatus for a vehicle having an electric motor, and a step-variable transmission selectively placed in a speed position with engagement of a coupling device, wherein the vehicle runs rearward with a reverse drive torque of the electric motor generated in a forward-drive low-speed position of the transmission, is provided. The control apparatus includes: a first shift control portion temporarily increasing an input torque of the transmission to raise its input speed toward a synchronizing speed in the low-speed position, and commands an engaging-side coupling device to be brought into its engaged state after the input speed has been raised to a predetermined value; and a second shift control portion increasing an engaging force of the engaging-side coupling device to bring the engaging-side coupling device into the engaged state.