Hybrid Vehicle Gear Shift Control via Input Speed Tracking
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Solution Overview
Problem
Hybrid electric vehicles face challenges in reducing gear-shifting time, minimizing drive system losses, and enhancing drivability, particularly in transferring acceleration changes to the driver during power-on upshift active control operations.
Innovation Solution
A method that involves starting gear shift control for power-on upshift to a target shift range, determining the slip of a release element in the transmission, calculating a transmission input shaft request torque based on vehicle driving information, and controlling the clutch torque of the engagement element to track a target change rate of the transmission input speed, ensuring synchronization before increasing clutch torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional gear shift control is used in hybrid electric vehicles, then the transmission structure is simple, but the gear-shifting time is long and drive system losses increase
Solution Approach 1:
The control method performs preliminary actions by pre-calculating the release element slip state and determining the engagement element clutch torque command value before the gear shift is completed. The system determines whether slip has occurred and calculates the appropriate torque command in advance, allowing for smoother and faster gear transitions with reduced energy loss.
Solution Approach 2:
The control method implements feedback by continuously monitoring the transmission input shaft speed and comparing it against the target change rate. The system adjusts the engagement element clutch torque command value based on the actual speed deviation, ensuring optimal gear shifting performance while minimizing drive system losses.
2Use of energy by moving object
If active control operation is performed during power-on upshift, then fuel efficiency is improved, but the driver cannot feel the change in acceleration when manipulating the accelerator pedal
Solution Approach 1:
The control method dynamically changes the transmission input shaft speed parameter by controlling it to track the target change rate during gear shift. This parameter adjustment allows the system to maintain fuel efficiency through active control while preserving the driver's ability to feel acceleration changes, as the speed tracking adapts to driver input rather than rigidly enforcing a predetermined shift schedule.
3Loss of time
If the transmission input speed is controlled to track the target change rate, then gear-shifting time is reduced, but the clutch torque control complexity increases
Solution Approach 1:
The control method replaces complex mechanical gear shift mechanisms with electronic control of the engagement element clutch torque. By using a motor controller to adjust the clutch torque command value based on speed deviation, the system achieves faster gear shifting without the mechanical complexity of additional shift mechanisms.
Data Source
AI summary
A method for controlling gear shifting of a hybrid electric vehicle, which is configured for reducing gear-shifting time, minimizing loss by a drive system, improving fuel efficiency and enhancing drivability and which enables a driver to feel a change in acceleration when the driver manipulates the accelerator pedal during power-on upshift active control operation may include speed control of the driving source of the vehicle based on a change rate of a transmission input speed and feedforward control of the clutch of the engagement element in the transmission, to which a driver requested torque is reflected, which are performed at the same time during power-on upshift active control operation, facilitating the driver to feel a change in acceleration which is produced by his or her driving manipulation.