AMT Shift Control via Dual Motor Torque Coordination
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Solution Overview
Problem
Automated manual transmissions (AMTs) experience torque interruption during gear shifting, leading to an unpleasant shifting feel and degradation in vehicle power performance, which affects driver convenience and vehicle merchantability.
Innovation Solution
A shift control method for AMTs using a combination of first and second motors and a planetary gear unit, where the torque of the second motor is increased to minimize output torque changes during shifting, and maintained constant during transmission release, speed synchronization, and coupling, while the first motor's torque is adjusted to follow predetermined target torque values, ensuring smooth and efficient power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the shift operation is automatically performed by actuators depending on driving situations, then driver convenience is improved, but torque interruption occurs causing unpleasant shifting feel and degradation in power performance
Solution Approach 1:
The second motor increases torque in advance before the shift operation to compensate for the upcoming torque interruption. By pre-loading the second motor, the system ensures that when the first motor disconnects during shifting, the output torque remains stable and the unpleasant shifting feel is prevented.
Solution Approach 2:
The control system dynamically changes the torque parameters of both motors during the shift process. The first motor's torque is reduced while the second motor's torque is increased, with the combined output maintaining a substantially constant value. This parameter coordination resolves the torque interruption issue while preserving automatic shifting convenience.
2Productivity
If the torque of the first motor is decreased during shift operation, then gear shifting is enabled, but output torque changes causing degradation in power performance
Solution Approach 1:
The patent merges the functions of two motors to achieve smooth power delivery during shifting. The first motor's power is gradually reduced while the second motor's power is increased, with both motors working together to maintain constant output torque. This combining of power sources eliminates the torque drop that would normally occur during gear shifting.
Solution Approach 2:
The control method ensures continuous power delivery to the output shaft throughout the entire shift process. By coordinating the torque reduction of the first motor with the torque increase of the second motor, the system maintains uninterrupted useful action, preventing any degradation in power performance during the gear transition.
3Power
If the torque of the second motor is increased to minimize output torque changes, then power performance is maintained, but device complexity increases
Solution Approach 1:
The control system acts as an intermediary that coordinates between the two motors and the shift actuator. It manages the complex interactions by implementing a control algorithm that increases the second motor's torque in response to the first motor's torque reduction, thereby maintaining stable output torque without requiring complex mechanical modifications to the transmission system itself.
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 method prevents torque interruption, enhances the shifting feel, and maximizes power performance by maintaining constant or increasing output torque, thereby improving the overall merchantability and acceleration response of the vehicle.
Implementation Method 1
a planetary gear unit, in which the first motor supplies power to a first rotating element of the planetary gear unit, the second motor supplies power to the first rotating element or a second rotating element of the planetary gear unit
Data Source
AI summary
A shift control method for an automated manual transmission (AMT) of a vehicle includes: when a shift operation is started, a torque of the second motor is increased so that a change in an output torque of the output shaft due to a change in a torque of the first motor is minimized while the torque of the first motor is being decreased. According to the shift control method, the increased torque of the second motor is maintained to be constant while controlling transmission release, speed synchronization, and transmission coupling. After the control over the transmission coupling is completed, the torque of the second motor is controlled so that the output torque of the output shaft follows a predetermined target torque while the torque of the first motor is controlled to be increased.