What is a plastic aggregate

Motors made of plastic and ceramics: Light and hot

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Bad news for Europe's automakers: The Japanese got the first ceramic engine running. And the Americans are already putting a plastic unit to the acid test of car races.

The small ceramic engine from the Far East could just about be downplayed as a sensational gimmick. But with the "Polimotor" from the Midwest no excuses help: With a displacement of 2.3 liters and an output of 74 kilowatts (100 hp), this miracle machine weighs only 80 kilos, of which only 30 kilos are metallic - namely, the cylinder surface , Valves, camshaft and crankshaft. Everything else consists of glass, carbon and wire fiber reinforced epoxy resins and the plastic polyamide.

The racing engine was developed by Ford from a production machine and, as the auto giant recently announced, should be half lighter, considerably less thirsty and 30 percent quieter than the metallic original. If the engine were for sale, it would currently cost around 70,000 marks.

In the motherland of the automobile, in Germany, development engineers bake small rolls, for example at the German Research and Research Institute for Aerospace (DFVLR) in the Pfaffenwald in Stuttgart. There they show visitors to the Institute for Building Methods and Construction Research a noise-dampening box in the backyard. Germany's first plastic engine chugs in it: a single-cylinder diesel with a displacement of 750 cubic centimeters and an output of 12.5 kilowatts at 3000 revolutions per minute. The only plastic part tested on this test rig so far is a piston pin made of carbon fiber reinforced plastic (technical abbreviation: CFRP). It weighs 60 percent less than its conventional metal counterpart.

But the first impression of hopeless backwardness towards the United States is deceptive. In the neighboring hall, connecting rods and crankshafts made of CFRP are already running in the endurance test, i.e. a complete plastic drive train. The designers achieved the greatest weight savings with the connecting rod (270 grams compared to 1.3 kilograms in the steel version). The CFRP crankshaft is - with the hoped-for equal load capacity - more than half lighter than in today's cars.

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A look at other laboratories and workshops at the Stuttgart Aerospace Research Center makes it clear why the DFVLR is also working on plastic car engines: Here, heavy-duty plastic variants for airplanes, helicopter rotors and rotor blades for wind power plants are designed, manufactured and tested. And this is also where the ceramics trail is walked.

Graduate engineer Richard Kochendörfer, department head of the Institute for Construction Research, sees no competition between plastics and ceramics in engine construction, but rather an effective addition: "Extremely resilient plastics such as CFRP enable a considerable reduction in the weight of the moving masses in the engine so that bearings with smaller dimensions and, overall, smoother running. "