Hybrid Planetary Gear Engine Start via Electric Machine Torque
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Solution Overview
Problem
Conventional clutch mechanisms in hybrid vehicle propulsion systems lead to heating, increased fuel consumption, wear, and space inefficiency, as well as friction losses in hydraulic converters, necessitating a more efficient method for starting the combustion engine.
Innovation Solution
A method where the combustion engine is started by using the electric machine to drive the vehicle in reverse gear, with a component brake controlling the sun gear connected to the output shaft of the combustion engine, allowing the engine to begin rotating with positive speed through the planetary gear, enabling simultaneous acceleration and engine start during ongoing vehicle movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional clutch mechanism is used to connect the input shaft of the gearbox with the combustion engine, then the vehicle can be driven with gear changing, but the clutch discs heat up resulting in increased fuel consumption and wear
Solution Approach 1:
The patent removes the conventional clutch mechanism from the propulsion system entirely. Instead of using a clutch to connect/disconnect the combustion engine from the gearbox, the system uses the electric machine to provide torque during gear changes and engine start-up, eliminating the need for friction-based clutch discs and their associated energy losses.
Solution Approach 2:
The patent replaces the mechanical friction-based clutch system with an electrically-controlled system. The electric machine provides the necessary torque to accelerate the combustion engine and manage gear changes without mechanical friction, substituting electromagnetic force for mechanical friction.
2Ease of operation
If a conventional clutch mechanism is used, then gear changing is possible, but the clutch mechanism is relatively heavy and occupies large space
Solution Approach 1:
The patent extracts and removes the heavy clutch mechanism from the propulsion system. By using the electric machine to provide torque during gear changes and engine start-up, the system eliminates the need for heavy clutch discs, pressure plates, and associated hardware, significantly reducing weight.
3Ease of operation
If a hydraulic converter/torque transformer is used, then automatic gearbox operation is achieved, but friction losses occur
Solution Approach 1:
The patent replaces the hydraulic converter/torque transformer with a direct mechanical connection through the planetary gear system. The electric machine provides the necessary torque multiplication and control without requiring fluid coupling, eliminating the friction losses associated with hydraulic converters while maintaining automatic operation capability.
4Reliability
If the combustion engine is started while the vehicle is stationary, then the engine can be warmed up, but the clutch mechanism experiences increased wear and heating
Solution Approach 1:
The patent removes the clutch mechanism that causes wear and heating during engine start-up. Instead, the electric machine directly accelerates the combustion engine through the planetary gear system, eliminating friction-based wear while maintaining the ability to warm up the engine before driving.
Solution Approach 2:
The electric machine serves dual purposes: it propels the vehicle during electric-only mode and simultaneously accelerates the combustion engine during start-up. This self-service capability allows the system to warm up the engine without requiring a separate clutch mechanism, reducing wear and heating.
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 simplifies the propulsion system control, reduces weight and size, and enhances energy efficiency by allowing the combustion engine to start during acceleration, particularly suitable for urban traffic, while maintaining compatibility with standard gearbox interfaces.
Implementation Method 1
the vehicle is driven forward by the electric machine while a reverse gear is engaged in the gearbox, by that the electric machine drives the ring gear of the planetary gear to rotate with a negative rotational speed
Implementation Method 2
the component brake brakes the sun gear, which is connected to the output shaft of the combustion engine
Implementation Method 3
the output shaft of the combustion engine is via the planetary gear brought to rotate with a positive rotational speed
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
A method for driving a hybrid vehicle in connection with start of a combustion engine (2) in a propulsion system (1) of the vehicle, which propulsion system comprises a planetary gear with three components in the form of a sun gear (10), a ring gear (11) and a planet wheel carrier (12). The output shaft (2a) of a combustion engine (2) is connected to a first of said components, an input shaft (3a) of a gearbox (3) being connected to a second of said components and the rotor (9b) of an electric machine (9) is connected to a third of said components. The method starts when the vehicle is being driven forward by the electric machine, which with a reverse gear engaged in the gearbox drives the third component of the planetary gear to rotate with a negative rotational speed while a component brake (28) brakes said first component. The method comprises the step to transfer the component brake to an open position, so that the output shaft of the combustion engine planetary gear is brought to rotate with a positive rotational speed, whereby the combustion engine may be started.