Diesel-electric transmission

Of the diesel-electric drive is a transmission system with the mechanical energy generated by large diesel engine is converted by a generator into electrical power and transmitted to the drive system of a machine. The most common applications are diesel-electric locomotives, submarines and ships, and large lorries (trucks ) as mining truck.

Principle

Diesel-electric drives are, strictly speaking, electric actuators, lead their own power plant in the form of a generator driven by a diesel engine with it. With the generated electric energy electric motors are supplied as direct drives for wheels or propellers.

The basis of this method is that diesel engines as all internal combustion engines can not be approached under load operated only in a narrow speed range with high efficiency and a. These weaknesses are avoided at smaller drive units (such as motor vehicles ) with a gearbox and a mechanical clutch, it is referred to as diesel- mechanical drive. For larger demands on the performance as locomotives or ships, either the diesel-hydraulic or diesel-electric drive used.

The diesel-electric propulsion has compared to the diesel-hydraulic the advantage of a relatively simple and not prone to disruption construction. In addition, due to the very small numbers are hardly hydraulic drive elements available in such sizes. In addition, the transmission can be easily controlled electronically so that during starting or braking an optimal comfort for the passengers can be achieved.

Lately, the use of three-phase generators with three-phase asynchronous motors prevails, together with an electronic power control IGBTs or GTOs, in which the frequency of the current is adjusted by frequency converter to the current driving situation.

The diesel-electric drive can be combined to form a hybrid drive, which allows operation even without the diesel engine by the electric traction motors their energy on certain routes from either batteries or - for rail vehicles - refer from an overhead line ( The definition of the UN does not expect the contact line variant, however, to the hybrid drives ). According to the logic, hybrid two energy sources that are pure diesel-electric version combining with accumulator, however, is not expected to give the hybrid drives, already.

Accumulators are sometimes also used to keep the diesel generators can always work at optimum speed range. If more power is produced than needed is cached. If less energy than needed, energy is taken from the battery.

Rail transport

The diesel-electric drive predominates worldwide haul locomotives. Only in Germany, a decision in favor of the diesel- hydraulic drive was hit in the 1950s, which lasted until the last acquired by the then German Federal Railroad in the 1970s diesel locomotives. Thus, the German Bahn AG had only diesel-electric locomotives (series 232-234 and 241 ) from the collections of the Deutsche Reichsbahn. Diesel-electric freight train locomotives have the level of 2004 power ratings up to 4400 kW.

When diesel-electric multiple units to electric traction motors can be used in other cars are than the diesel generator. The intercity trains British Rail Class 220, the diesel engines are machines in trolley at the ends of the train, electric traction motors in trucks of all intermediate cars.

The Rotterdam tramway built for their overland routes 1961-1963 their trainset M 17 from two used electric tramcar with a former diesel multiple units as a generator wagon in the middle.

In the gear train Diakopto - Kalavryta in Greece was located on the same design principle of a generator car between the two railcars. The route had greater axle loads are not allowed, so that the " power plant " was outsourced to a separate vehicle.

Buses and Coaches

• The London bus operation Thomas Tilling took from 1911 to 1925 in several series hundreds of Tilling Stevens Petrol- Electric buses ( biplane and monoplane ) in operation, which combined an internal combustion engine with an electric drive. Since the diesel engine was not yet mature, a gasoline engine was used. The last buses were taken out of service in 1933.
• In the 1930s there were numerous U.S. cities hundreds of city buses with diesel-electric drive. For example, it was in Newark, both over 500 diesel-electric buses and 500 trolleybuses, which were also equipped with a diesel engine to drive regardless of the catenary in the inner city can (so-called "all- service" buses). This duo buses went up in 1948, the simple diesel-electric buses were by the end of 1955.
• 1946-1950 a diesel-electric bus in an edition of 1165 copies was produced in the Soviet Union under the name ZIS -154.
• 1964 in Charleroi (Belgium ), the prototype of a bus line designed and constructed its diesel engine was in the rear directly connected to a three-phase generator, and equipped at the rear with two DC motors as hub motors. This could be a low for that time floor height of 600 mm can be achieved.
• Daimler -Benz had for some years the Midibus Cito (O 520) in the offer, which featured a diesel-electric drive. This model is now discontinued.
• New Bus for London

Specialized Vehicles

• The dump truck ' Liebherr T 282 B' for use in ore mines the company says is the largest country vehicle with a diesel-electric drive. Special features: The vehicle used for reasons of reliability and reduced maintenance costs no conventional service brake but slows down primarily through the two electric drive motors, each of which is mounted directly behind each wheel hub on the rear axle. In this arrangement can also be dispensed with a differential gear, as the speed of each wheel is independently controlled. The power of the electric motors is designed for the necessary braking power at full load and is about twice as high as that of the driving 2700 kW diesel engine. The recovered during braking electrical energy is converted into heat via the braking resistors.

Ships

• Raccoon dog
• Queen Mary 2

References

• Combustion engine
• Hybrid drive
• Electric vehicle drive