Hybrid Drivetrain Clutch Control for Overheating and Smooth Engine Start
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Solution Overview
Problem
Existing methods for operating hybrid vehicles fail to provide reliable protection against clutch overheating with high dynamics, affecting ride comfort and not effectively preventing rapid temperature increases in clutches during continuous slip operations.
Innovation Solution
A method involving a motor vehicle drive train with an internal combustion engine, electric machine, and transmission, utilizing a starting component like a hydraulic torque converter or friction clutch, and a separating clutch to manage differential speed, allowing the electric machine to crank the engine, keeping energy input low and avoiding clutch overheating by controlling rotational speeds and engaging the internal combustion engine only when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the second clutch is operated in a slip state to avoid overheating, then the temperature of the clutch is reduced, but the ride comfort deteriorates and the response dynamics are slowed
Solution Approach 1:
The system dynamically switches between two operating modes based on clutch temperature: a first mode with high dynamics for normal operation and a second mode with temperature protection for thermal management. This dynamic adaptation allows the system to optimize between ride comfort and temperature control in real-time.
Solution Approach 2:
The control system periodically monitors clutch temperature and alternates between different operating modes. When temperature thresholds are exceeded, the system transitions to a protective mode with reduced differential speed, then returns to normal operation when temperatures decrease, creating a periodic control pattern.
2Temperature
If the clutch is operated continuously in slip state to manage temperature, then thermal stress is reduced, but the temperature increases very rapidly and overheating protection becomes unreliable
Solution Approach 1:
The system performs preliminary actions by pre-charging the clutch in a first operating mode before transitioning to the second mode. This ensures the clutch is ready for immediate engagement when temperature protection is needed, preventing rapid temperature increases during mode transitions.
Solution Approach 2:
The control system continuously monitors clutch temperature and uses this feedback to determine when to switch between operating modes. This closed-loop control ensures reliable overheating protection by responding to actual temperature conditions rather than relying on predetermined timing.
3Temperature
If the electric machine rotational speed is reduced to protect the clutch, then the differential speed and thermal load are reduced, but the drive performance and acceleration capability deteriorate
Solution Approach 1:
The system dynamically adjusts the electric machine rotational speed based on clutch temperature conditions. In the first mode, high rotational speeds provide optimal drive performance. In the second mode, rotational speed is reduced to protect the clutch, with smooth transitions between modes to minimize performance impact.
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 approach effectively prevents clutch overheating by managing energy input and differential speeds, ensuring smooth transitions and reducing thermal stress on clutch components, while providing acoustic feedback to the driver.
Implementation Method 1
the internal combustion engine is cranked using the electric machine
Implementation Method 2
The starting component permits a torque transmission between at least one of the drive sources of the drive train and the output shaft while forming a differential speed
Implementation Method 3
A separating clutch, particularly a friction clutch, is arranged in the power flow between the internal combustion engine and the electric machine
Data Source
AI summary
A method for operating a drive train having a starting component between an electric machine and an output shaft of a transmission, and a separating clutch between an internal combustion engine and the electric machine, with a rotor of the electric machine being coupled to the input shaft of the transmission, where the method initially drives a motor vehicle solely by the electric machine while the starting component is engaged or slipping and the separating clutch is disengaged. The method then engages the separating clutch to crank the internal combustion engine. The method disengages the separating clutch after cranking, with an output-side rotational speed of the separating clutch being lower than an idling speed of the internal combustion engine. Subsequently, the method engages the separating clutch to drive the motor vehicle with the internal combustion engine when a target drive torque reaches or exceeds a limit.