Hybrid EV Gearshift Control for Dual Mass Flywheel Shift Shock
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Solution Overview
Problem
Hybrid electric vehicles experience shift shock when a shift clutch is engaged due to differences in angular velocity between the engine and the transmission input terminal, caused by the abnormal stretching and compression of the spring in the dual mass flywheel during gearshift intervention control.
Innovation Solution
A control method for hybrid electric vehicles that synchronizes the angular velocity of the engine with the target angular velocity of the transmission input terminal by controlling the torque of the first motor connected to the engine, based on the gear shifting progress rate, to alleviate shift shock during gearshift intervention control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intervention control is performed through the electric motor during gearshift, then the torque of the driving source is decreased to protect the clutch and reduce kinetic energy, but the spring inside the dual mass flywheel is abnormally stretched and compressed causing shift shock
Solution Approach 1:
The control unit determines a target angular acceleration for the engine based on the gear shifting progress rate before the shift clutch is fully engaged. By preparing the engine's angular acceleration in advance to match the transmission input terminal's target angular acceleration, the system prevents the abnormal spring compression that causes shift shock, while still implementing intervention control to protect the clutch.
Solution Approach 2:
The control unit continuously monitors the gear shifting progress rate and adjusts the engine's target angular acceleration in real-time based on this feedback. This closed-loop control ensures that the engine's angular acceleration follows the transmission input terminal's target angular acceleration throughout the gearshift process, preventing shift shock while maintaining clutch protection.
2Productivity
If the angular velocity of the engine is not synchronized with the target angular velocity of the transmission input terminal, then the gearshift intervention control can be performed, but the difference in angular velocity causes shift shock when the shift clutch is engaged
Solution Approach 1:
The control unit determines the target angular acceleration of the engine in advance based on the gear shifting progress rate, before the shift clutch engagement is complete. This preliminary adjustment ensures that when the clutch engages, the engine and transmission input terminal are already synchronized in angular acceleration, preventing shift shock without delaying the gearshift process.
Solution Approach 2:
The control unit dynamically changes the engine's target angular acceleration parameter during the gearshift process based on the gear shifting progress rate. By adjusting this parameter to match the transmission input terminal's target angular acceleration, the system eliminates the angular velocity difference that causes shift shock, while maintaining efficient gearshift execution.
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
The method effectively reduces shift shock when the shift clutch is engaged, improves the durability of the transmission, and enhances the fuel efficiency of the hybrid electric vehicle by minimizing the need for intervention control.
Implementation Method 1
a dual mass flywheel (DMF) is disposed on the output side of the engine, which may perform a function of dampening vibration generated in the driving of the engine by arranging an arc damping spring between two flywheels
Implementation Method 2
the spring inside the dual mass flywheel is abnormally stretched and compressed
Data Source
AI summary
A method for controlling a hybrid electric vehicle includes: connecting a first motor directly connected to an engine to a second motor directly connected to a transmission input terminal through a dual mass flywheel; determining a target angular acceleration of the first motor according to a gear shifting progress rate so that an angular acceleration of the first motor follows a target angular acceleration of the transmission input terminal when a gearshift is performed in the transmission; and controlling a torque of the first motor based on the target angular acceleration of the first motor.