Several types of hybrid-electric vehicles have been developed at Ford Research Laboratory. Among the parallel hybrid systems with a single electric motor, two types were studied. In the first type, the electric motor was attached directly to the crankshaft (mild hybrid) to enable the engine start-stop and regeneration functions. In the second type (full hybrid) the electric motor was connected to the engine through the use of a clutch to allow electric launch of the vehicle and pure electric driving at low speeds. The full hybrid powertrain described in this paper uses a more powerful electric motor for enhanced regenerative braking and engine power assist. An engine-disconnecting clutch saves energy during both the electric propulsion and during vehicle braking. When the clutch is disengaged the engine is shut-off, which eliminates the energy otherwise spent on motoring the engine during electric propulsion. Similarly, during the vehicle braking the energy, that otherwise is wasted on motoring the engine, is collected in the battery. Finite element models have been used to analyze the dynamic variation of the rotor gap, as it is affected by the crankshaft bending and the clutch engagement heat. Conclusions: 1. Crankshaft bending: When the rotor is supported by ball bearings on each side, the maximum deflection of the centerline of the rotor is only 4 microns. This variation is small enough to ensure absence of the rotor 'whirl' and the durability of the crankshaft. However, a lower cost non-bearing design may also be possible, if the number of splined connections and their tolerances are reduced. 2. Thermal effects of clutch engagement: The engine-disconnecting clutch has much easier job of cranking the engine compared to a driveline clutch that pulls the vehicle. Thus, even when the clutch is located inside the rotor, the heat transfer for the chosen clutch design insignificant. The design analysis includes a dynamic analysis of bearing loads for the crankshaft, starter-alternator, and transmission input shaft. In addition, other aspects discussed here include stator and rotor alignment, clutch design, slave cylinder and clutch actuator, and other details.
Hybrid powertrain with an engine-disconnecting clutch
Hybride Kraftübertragung mit Trennkupplung
2002
10 Seiten, 18 Bilder, 4 Tabellen, 3 Quellen
Aufsatz (Konferenz)
Englisch
Hybrid Powertrain with an Engine-Disconnecting Clutch
British Library Conference Proceedings | 2002
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SAE Technical Papers | 2002
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