Hybrid Vehicle Engine Starting via Twin-Clutch Torque Control
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Solution Overview
Problem
Vehicles with hybrid propulsion face challenges in starting a cold thermal engine due to the inability of electric machines to generate sufficient torque, leading to increased mechanical stress and discomfort from vibrations and oscillations when starting a warm engine, and existing solutions are either complex or inefficient.
Innovation Solution
A method using a twin-clutch gearbox and an electronic power converter to control the torque distribution between the electric machine and the thermal engine, allowing for maximum torque generation and slip in clutches to absorb vibrations, ensuring rapid and comfortable starting without excessive stress on components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the electric machine is mechanically connected to the drive shaft with a low gear-down ratio, then the structure is simple, but the electric machine cannot generate sufficient starting torque for a cold thermal engine
Solution Approach 1:
The patent applies a dynamic approach by making the gear-down ratio variable rather than fixed. The transmission system automatically selects between a first gear-down ratio (higher reduction) for starting operations and a second gear-down ratio (lower reduction) for normal operation. This dynamic adaptation allows the electric machine to generate sufficient starting torque when needed while maintaining simple mechanical connection during normal operation.
2Force
If a servo controlled gearbox is interposed to provide high gear-down ratio for starting, then the starting torque is sufficient, but the device complexity increases
Solution Approach 1:
The patent segments the transmission system into distinct operational modes with different gear-down ratios. Instead of using a complex servo-controlled gearbox, the system divides the starting function into a specific operational phase where a higher gear-down ratio is temporarily applied, then transitions to normal operation with lower ratio. This segmentation allows high starting torque without permanently complexifying the entire transmission system.
3Force
If the clutch is opened and electric machine rotated with no load before closing, then the inertia is exploited to start the engine, but unnecessary mechanical stress and delay occur when the engine is warm
Solution Approach 1:
The patent changes the operational parameters dynamically based on engine temperature. When the engine is cold, the system applies a higher gear-down ratio to generate sufficient starting torque. When the engine is warm, the system automatically switches to a lower gear-down ratio, avoiding unnecessary mechanical stress and time delay. This parameter adaptation eliminates the harmful effects of the launched starting method during warm engine conditions.
4Productivity
If the vehicle moves initially with electric machine only, then the inertia is used to start the thermal engine, but sudden braking and oscillations occur during starting
Solution Approach 1:
The patent applies beforehand cushioning by preparing the transmission system with appropriate gear-down ratio selection before the starting operation. The system anticipates the starting requirement and pre-configures the transmission to provide smooth torque transfer. This prevents sudden braking effects and vibrations by ensuring the thermal engine is gradually brought into operation rather than suddenly connected, cushioning the transition for the vehicle.
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
Enables rapid and comfortable starting of the thermal engine in all conditions without excessive mechanical stress, eliminating sudden braking and oscillations, and is cost-effective with minimal additional components required.
Implementation Method 1
slip in clutches to absorb vibrations
Data Source
AI summary
A starting method of an internal combustion thermal engine of a vehicle with hybrid propulsion provided with a transmission equipped with a twin-clutch gearbox and a reversible electric machine connected to a first primary shaft; the starting method including the steps of: making the electric machine work as an engine for producing a torque; partially closing a first clutch connected to the first primary shaft in order to make the first clutch itself slip to transmit part of the torque generated by the electric machine to a drive shaft of the thermal engine; engaging a gear coupled to a second primary shaft to mechanically connect the second primary shaft itself to the driving wheels; and closing partially a second clutch connected to the second primary shaft in order to make the second clutch itself slip and transmit part of the torque generated by the electric machine to the driving wheels.