Hybrid Launch Control Engine Pre-Boosting Torque Transfer
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Solution Overview
Problem
Hybrid vehicles face challenges in enhancing launch acceleration performance, as existing methods do not effectively reflect the driver's acceleration intent, leading to suboptimal torque transfer and efficiency during launch.
Innovation Solution
A launch control method for hybrid vehicles that includes determining the driver's intent to execute a launch control mode, synchronizing engine and motor speeds, performing slip control, engine pre-boosting, take-up control, and locking up the slip element to improve acceleration performance by optimizing torque transfer between the engine and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the hybrid vehicle launches in EV mode with motor torque only, then the system complexity is reduced and ease of operation is improved, but the launch acceleration performance is insufficient when transmission input torque capacity exceeds maximum motor torque
Solution Approach 1:
The system dynamically switches between EV mode and HEV launch control mode based on driving conditions and driver intent. The launch control mode engages the engine clutch and coordinates engine-motor torque when high acceleration is required, while EV mode operates with motor-only torque for normal conditions, providing adaptive performance optimization.
Solution Approach 2:
The system changes operational parameters by transitioning from pure electric mode to hybrid mode, adjusting engine clutch engagement state, torque distribution ratios, and coordination control parameters between engine and motor to maximize launch acceleration performance when conditions warrant.
2Speed
If the engine is started and engaged during launch, then the maximum allowable input torque of the transmission can be fully utilized to improve acceleration performance, but the torque generation delay of the engine reduces responsiveness
Solution Approach 1:
The system performs preliminary engine starting and speed synchronization before full torque engagement is needed. The engine is cranked and its speed is pre-synchronized with the motor speed while the vehicle is still stationary or moving slowly, so that when the engine clutch engages, the engine is already ready to deliver torque without delay.
Solution Approach 2:
The motor acts as an intermediary during the transition phase, providing torque to the transmission input terminal while the engine is being started and synchronized. This allows the system to utilize maximum transmission torque capacity immediately through the motor, bridging the gap until the engine is ready to contribute.
3Speed
If slip control is performed on the slip element between motor and transmission, then torque transfer is optimized and acceleration performance is improved, but the control complexity increases
Solution Approach 1:
The system implements feedback control by continuously monitoring the rotational speeds of the motor and transmission input terminal, calculating the speed difference, and adjusting the motor torque and slip element engagement accordingly. This closed-loop control optimizes torque transfer through the slip element while maintaining stability.
4Stability of the object's composition
If the engine and motor speeds are synchronized before engine clutch engagement, then smooth power transfer is achieved, but the control process complexity increases
Solution Approach 1:
The control system acts as an intermediary by coordinating the engine and motor speeds through a synchronization process. The motor speed is adjusted to match the engine speed (or vice versa) before clutch engagement, ensuring smooth power transfer without mechanical shocks or vibrations.
Data Source
AI summary
A launch control method for a hybrid vehicle includes: determining an intent of a driver to execute a launch control mode in a state in which an engine is turned-off; when the intent of the driver is to execute the launch control mode, starting the engine and controlling an engine speed; performing a slip control on a slip element of a transmission input terminal; when the engine speed is synchronized with a motor speed or a difference between the engine speed and the motor speed is less than a predetermined range, locking up an engine clutch; when the engine clutch is locked up, performing an engine pre-boosting control to raise an engine torque to a torque at which battery charging is available due to a motor; performing a take-up control on the slip element; and when the take-up control is terminated, locking up the slip element.