Hybrid Vehicle Clutch Slip Control for Engine Starting Shock
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Solution Overview
Problem
Hybrid vehicles experience engine starting shock due to direct transmission of torque variations between cranking and initial combustion when the engine is started while the vehicle is moving, causing discomfort to passengers and drivers.
Innovation Solution
A hybrid vehicle drive control system that selectively engages a clutch with maximum torque transfer capacity from the gear position clutches during engine starting, using slip control to mitigate torque fluctuations and prevent engine stalling or juddering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine is started while the vehicle is moving in electric drive mode, then the vehicle can transition to hybrid drive mode to improve power availability, but torque variations during cranking and initial combustion are directly transmitted to the transmission output axle causing shock and discomfort
Solution Approach 1:
The patent introduces a second clutch as an intermediary component between the transmission output axle and the driven wheels. This second clutch acts as a mediator that decouples the direct torque transmission path, allowing torque variations during engine starting to be isolated from the driven wheels. The first clutch connects the engine to the motor/generator, while the second clutch connects the transmission output to the driven wheels, creating a buffer zone that prevents shock transmission.
Solution Approach 2:
The patent segments the torque transmission path by introducing a separate second clutch that is independent from the existing first clutch and gear position clutches. This segmentation allows the torque transfer capacity of the second clutch to be independently controlled during engine starting, enabling selective engagement or disengagement to mitigate shock while maintaining drivetrain connectivity.
2Productivity
If the clutch is completely engaged during engine starting, then torque can be transmitted efficiently, but torque variations are directly transmitted causing shock and potential engine stalling
Solution Approach 1:
The patent applies dynamic control to the second clutch by varying its torque transfer capacity during the engine starting process. Instead of maintaining a fixed completely engaged state, the control unit dynamically adjusts the second clutch's engagement level based on engine operating conditions. This dynamic adjustment allows the system to optimize between torque transmission efficiency and shock mitigation, preventing engine stalling while maintaining drivetrain connectivity.
3Object-affected harmful factors
If the torque transfer capacity of the second clutch is reduced during engine starting, then shock is mitigated, but torque capacity shortages may occur affecting vehicle operation
Solution Approach 1:
The patent implements a feedback control mechanism where the control unit continuously monitors engine operating parameters such as cranking speed and adjusts the second clutch's torque transfer capacity accordingly. The control unit receives feedback from the engine's starting progress and dynamically modulates the second clutch engagement to maintain optimal torque capacity while mitigating shock. This feedback loop ensures that torque capacity is reduced only to the extent necessary for shock mitigation, preserving sufficient power 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
The system effectively reduces engine starting shock and prevents torque capacity shortages, ensuring stable vehicle operation by controlling torque transfer during engine start-ups in electric drive mode.
Implementation Method 1
a first clutch disposed between the engine and the motor/generator for selectively changing a torque transfer capacity between the engine and the motor/generator
Implementation Method 2
selecting a second clutch to be slip controlled by detecting which of the gear position clutches that are engaged to constitute the vehicle running gear occurring from immediately before starting the engine until immediately after starting the engine have the maximum torque transfer capacity
Data Source
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AI summary
A hybrid vehicle drive control system has a first clutch interposed between an engine and a motor/generator, a transmission including several gear position clutches arranged between the motor/generator and a drive wheel, and a controller. The controller selectively starts the engine using torque from the first clutch during a mode drive change from an electric drive mode to a hybrid drive mode. When an engine start command occurs during the drive mode change, the controller selects the engaged gear position clutch that has the maximum torque transfer capacity from the engaged clutches constituting a vehicle running gear occurring during an engine starting process as a second clutch to be controlled. Then the controller executes a slip control of the second clutch when the first clutch is being connected to start the engine during the mode change from the electric drive mode to the hybrid drive mode.