Engine: Laser replaces spark plug

New development reduces fuel consumption

Laser replaces spark plug CTR
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Researchers at Carinthian Tech Research have developed a miniature laser that can soon replace the spark plug. Advantage: Both fuel consumption and pollutant emissions are reduced significantly.

Laser adapts in geometry to the motor

Save fuel, reduce pollutants and improve performance at the same time - many drivers and car manufacturers have these requirements. The Carinthian Tech Research (CTR) from Villach and the AVL List in Graz have now set a new milestone in engine development together. The laser replaces the spark plug and gets the car up and running. The special feature is that for the first time it was possible to accommodate a complete laser with sufficient power to ignite a gasoline mixture in the installation space of a spark plug. Up to now, the motor has always had to be adapted to the laser in a complex manner or the laser beam has to be led into the combustion chamber via glass fibers. Thus, all experiments were limited to pure research. Now, the geometry of the laser adapts to the motor, clearing the way for "real" applications.

In addition to the laser shape, efficiency is also important to AVL List. Here, the CTR has achieved an efficient implementation of the electric power: The laser ignition electronics can be operated with a normal 12V car battery. So far, attempts have always been made to reduce the size of conventional spark plugs. However, the spark plug diameter is limited by the insulator properties. With the laser spark plug, this limitation is also lifted.

A miniature laser with many advantages

The CTR experts have succeeded in miniaturizing the laser to this spark plug dimension and integrating it directly in the engine. By comparison, a conventional laser with the same power is about 10 times larger than the ignition laser developed by CTR. The development was only made possible by state-of-the-art high-performance laser diodes.

The laser ignition offers several advantages. On the one hand, the relatively freely selectable location of the ignition plasma allows the optimization of the combustion process and possibly also enables multiple ignition (multipoint ignition). In contrast to conventional spark plugs, the laser spark plug also has no parts in the combustion chamber, which allows relatively complete, low-emission combustion and less material wear. In addition, laser ignitions can ignite even leaner mixtures, resulting in lower CO2 emission levels. display

The laser ignition process under harsh conditions

The power of the focused laser pulse is sufficiently intense to produce a plasma ball, which leads to a local temperature increase and thus enables the ignition of the fuel-air mixture in the gasoline engine. Dereigen's CTR-developed laser was successfully tested on the test engine at AVL List. The Carinthian developers designed the laser, the housing for installation in the spark plug shaft, as well as the control electronics. "The laser ignition system has been developed for use in gasoline or gas engines. The biggest challenge was to integrate a laser in a small space that would withstand the vibrations that occur at the engine and function stably even at high temperatures (up to 300 Celsius).? Says Gerhard Kroupa, project manager of the CTR. Ru and deposits on the optical window in the combustion chamber are burned away by the laser itself.

Theoretical studies and research have been around for some time. For the first time ever, the CTR has succeeded in producing a laser prototype of this dimension and performance, which, after initial tests, works successfully directly on the engine and can serve as a basis for future production engines. Steps for patenting and further developing the system have been taken together with AVL.

(ots, CTR, 19.07.2004 - DLO)