Hybrid Vehicle Control System Torque Transition
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Solution Overview
Problem
Hybrid vehicles face challenges in smoothly switching from motor mode to engine mode due to temporary shortages of engine torque, leading to deviations between target and actual driving forces when increasing requested driving force, making appropriate mode switching difficult.
Innovation Solution
A vehicle control apparatus that includes an electric motor, engine, clutch mechanism, and torque converter, with a control system that starts the engine and engages the clutch mechanism while controlling the electric motor based on a transition driving force larger than the initial force, and then adjusts both the electric motor and engine based on a second driving force after a delay time, ensuring accurate torque control and mode switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the traveling mode is switched from motor mode to engine mode in response to an increase in requested driving force, then the vehicle can utilize engine power, but temporary shortages of engine torque occur during the switching process
Solution Approach 1:
The control system starts the engine and engages the clutch mechanism in advance before the actual mode switching is completed. By performing these preparatory actions while still in motor mode or during the transition phase, the engine is ready to immediately provide torque once the clutch engages, eliminating the temporary torque shortage that would otherwise occur during mode switching.
Solution Approach 2:
The control system compensates for the expected temporary torque shortage by maintaining electric motor output at a higher level during the switching transition. This cushioning effect ensures that the total driving force remains sufficient even when engine torque is temporarily unavailable, preventing deviations between target and actual driving forces.
2Productivity
If the engine is started up and clutch mechanism is engaged immediately upon mode switching request, then the engine mode can be activated, but deviations between target and actual driving forces occur
Solution Approach 1:
The control system continuously monitors the actual driving force and compares it with the target driving force during the mode switching process. Based on this feedback, the control system adjusts the electric motor output and engine torque to minimize deviations, ensuring that the actual driving force closely follows the target driving force throughout the transition.
Solution Approach 2:
The control system dynamically adjusts the requested driving force distribution between the electric motor and engine during the switching process. Rather than maintaining a fixed driving force request, the system modifies the driving force allocation in real-time based on the switching phase, allowing for smooth transitions while maintaining control accuracy.
3Speed
If the electric motor is controlled based on the second driving force immediately, then the response to accelerator operation is faster, but the torque converter cannot effectively transmit engine torque
Solution Approach 1:
The control system waits for a predetermined period after engine start-up and clutch engagement before fully transitioning to engine-based driving force control. This preliminary waiting period allows the torque converter to establish proper hydraulic coupling and the clutch to fully engage, ensuring that engine torque can be effectively transmitted before the electric motor is reduced to auxiliary status.
Solution Approach 2:
During the predetermined waiting period, the electric motor maintains higher output levels to cushion against any potential torque transmission delays. This ensures that the vehicle continues to receive sufficient driving force while the torque converter and clutch mechanism establish their optimal operating state for torque transmission.
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 solution enables smooth and accurate switching to the engine mode by managing the transition of driving forces, reducing deviations and providing a comfortable driving experience by ensuring the engine torque is effectively transmitted, thus addressing the temporary torque shortages and mode switching challenges.
Implementation Method 1
a torque converter, and a control system. The torque converter is provided on the power transmission path
Data Source
AI summary
A vehicle control apparatus to be applied to a hybrid vehicle includes an electric motor, an engine, a clutch mechanism, a torque converter, and a control system. In a case of switching a traveling mode of the hybrid vehicle from a motor mode to an engine mode in response to an increase in requested driving force from a first driving force to a second driving force resulting from an operation of an accelerator of the vehicle, the control system starts up the engine and engages the clutch mechanism while controlling the electric motor based on a transition driving force larger than the first driving force. After a lapse of a delay time from completion of starting up of the engine and engaging the clutch mechanism, the control system controls the electric motor and the engine based on the second driving force larger than the transition driving force.