Test drive Magic Fires: The history of compressor technology II

The second part of the series: The era of compressors - past and present

“Karl braked imperceptibly and the Buick slowly overtook us. Wide shiny wings crawled past us. The muffler spewed blue smoke loudly in our faces. Gradually, the Buick gained about twenty meters of lead, and then, as we expected, the owner's face appeared in the window, grinning triumphantly.

He thought he had won ... He gave us signals especially calmly, confident in his victory. At that moment Karl jumped up. The compressor exploded. And suddenly the hand waving from the window disappeared when Karl accepted the invitation and approached. He approached uncontrollably.

1938 Erich Maria Remarque. "Three Comrades". A doomed love, a devastated soul, and the value of a few dozen little things that remind us that we appreciate simple things only when they fade away smoothly and irreversibly. A novel about the privilege of living here and now, rowing handfuls of the joys of life, a masterpiece about immense human values and ... Carl is a car with a modest ego, but with a boundless soul.

Three Comrades was published at a turning point in human history in 1938. Just months after publication, on September 1, 1939, the day the Grand Prix cars competed in a fierce race for the Yugoslav Grand Prix, German tanks crossed the border into Poland and led humanity to its greatest downfall. This day marks the end of an era in the automotive industry. The era of compressors is coming to an end.

Until recently, the meticulously written German word "Kompressor" was visible on quite a few Mercedes models. Of course, it would be much more convenient to use a simple abbreviation such as CDI or CGI, but the scrupulous spelling of the whole word in this case is not accidental. Without it, much of the marketing impact would have been lost if the challenge arose to recall those glorious times in the life of a luxury car manufacturer, when everything was based on the Kompressor oder Nichts motto (compressor or nothing).

The acronym TSI on the plastic hood of the VW Golf GT in 2005 was much more restrained and not meant to build bridges to some glamorous heritage. Excessive modesty is definitely not one of the qualities of VW, and the Wolfsburg manufacturer would not miss the opportunity to recall some of its successes, but in this case, the TSI label had to showcase the technical avant-garde, not tradition. The technological formula used by VW engineers was as trivial as an idea, as complex as implementation - a small engine (in this case, only 1,4 liters) provides excellent dynamic performance and an impressive power of 170 hp. thanks to the tandem of a powerful turbocharger and a small but efficient mechanical unit that fills the "hole" ravaged by the large power of the turbocharger and acts as a kind of dope against the initial engine failure. And just when we thought the idea was a success, a new line of two-litre engines entered the scene. Volvo, the most powerful of which has the same refueling system with mechanical and turbochargers. All this prompts us to return to history and recall the distant prototypes of modern engineering masterpieces. Yes, masterpieces, because the development of Volvo has once again put on the agenda an extremely interesting technical solution that was successfully used in a super-expensive racing car two decades ago. Spear Delta S4.

As already mentioned, there is nothing complicated or strange about the conceptual idea of VW and Volvo engines. We have long lived through the neuralgic theme of high fuel prices and the complex set of challenges that modern automotive designers face in their quest to create both dynamic and fuel efficient powertrains.

The whirlwind of technological excitement could not bypass compressors in their two varieties. Moreover, today turbochargers are among the main players in the race for maximum efficiency, adding new fuel to the fire of an old story that dates back to 1885 ...

Rudolph Diesel and compressor machines

There is something of the sentimental flavor of a late 1896th-century novel about the first internal combustion-engine automobiles. However, their creators were not just ambitious and ignorant "alchemists" and crazy experimenters, but usually highly educated people whose inventions are based on a serious scientific basis. It is this solid knowledge base that awakens in the mind of Gottlieb Daimler the idea of equipping his petrol and kerosene engines with an external compressor machine. Unfortunately, his first attempts in this direction were unsuccessful, and in the end he abandoned further development. Apparently, at that time, the chances of pre-compressing the fresh air entering the cylinders were extremely small - suffice it to say that Daimler again engaged in active research in this area only after the end of the First World War. The path of Rudolf Diesel is similar. At the same time that he was trying to run his patents in a major oil company and ended up selling them expensive and too expensive to the Swedish Nobel brothers working in the Russian oil fields of the Caucasus, he drew diagrams and figured out how to further improve efficiency. its a fairly efficient heat engine in principle. A fact little known today is that Diesel installed a precompression unit on its second laboratory sample, working at the MAN development base in Augsburg, and in December XNUMX a whole series of diesel engines equipped with compressors appeared.

Much later, the role of the main assistant of the diesel engine will be played by the exhaust turbocharger, thanks to which the invention of Rudolf Diesel will rise to its current rank. The first experimental Rudolf Diesel engines with a mechanical compressor noted the expected significant increase in power, but from an efficiency point of view, things were not so rosy. Diesel, for which the economy of the engine is of paramount importance, assesses the results of its own experiments as negative. For a brilliant engineer, they become an absolute and insoluble enigma, contrary to his well-known laws of thermodynamics. After completing his experiments in this area, he wrote the following in his notebook: “An experiment conducted on January 28, 1897, and comparison with previous experiments on January 12, raised the question of the effect of pre-compression. Obviously, this is extremely harmful, so from now on we must abandon this idea and focus on a conventional four-cylinder engine with direct intake of fresh air from the atmosphere in its current form. " Thank God, the genius Diesel is deeply mistaken here! Later it became clear that it was not the idea of forced filling that was wrong, but the way of its implementation….

Compressor diesel engines on ships

After a series of unsuccessful experiments by Rudolf Diesel and the erroneous conclusions that followed them, the designers for a long time abandoned the use of such a device for the forced supply of additional fresh air, relying solely on natural atmospheric pressure. The only orthodox and proven way to achieve more power at that time was to increase the displacement and speed level, since the latter is technologically feasible. The mist of delusions lingered for two decades, until the technology reached the required level, and the MAN engine company from the German city of Augsburg again put this idea on the agenda. As a result of the intensive work of the company in the early 20s of the last century, the first mass-produced diesel units with forced refueling using a mechanical compressor appeared. In 1924 there were already ships with compressor diesel engines, among which one can find an interesting technological solution in which the compressors are not driven directly from the crankshaft, but from specially adapted electric motors (you noticed the analogy with today's V8 diesel on Audi), as a result which increases their power from the standard 900 to 1200 hp. Of course, in all these cases we are talking about mechanically driven units - although at the beginning of the century the idea of \uXNUMXb\uXNUMXbthe gas compressor was patented, by the time it is implemented in serial models, it will be a long time. . The extremely slow development of compressor technology is due to two main reasons - poor awareness of the behavior of gasolines with their inherent tendency to knock and uncertainty about the efficiency of various types of compressor units.

The filling of gasoline engines began in 1901, when Sir Dugald Clerk (who was one of the pioneers of two-stroke engines, by the way) decided to use a pump to force additional fresh air into the combustion chambers. engine with a huge displacement. The clerk takes heat engine problems seriously and scientifically, and with this device seeks to deliberately increase the thermodynamic efficiency of the engine. However, in the end, he, like Diesel before him, only managed to increase his power.

The most commonly used Roots compressors today are based on a pumping device patented by Frank and Philander Roots of Indiana in the 1907s. The principle of operation of the Roots unit is borrowed from the gear pump invented in the 100th century by Johannes Kepler, and the first experiments of Gottlieb Daimler and his chief engineer Wilhelm Maybach were based on Roots compressors. The most impressive result of mechanical positive filling, however, comes from the American Lee Chadwick, who in 80 installed a compressor on the huge six-cylinder engine of his car, the working speed of which is nine times the speed of the crankshaft. Thus, Chadwick achieved a monstrous increase in power, and his car became the first in the world to reach the officially registered speed of XNUMX miles per hour. Of course, in the early days of this technology, many designers experimented with various other types of compressor devices such as centrifugal and vane. Patent applications include the predecessor to the rotary piston compressor, widely used in the XNUMX-ies of the last century by several companies, as well as the vane compressor by Arnold Theodor Zoller.

As a result, forced filling justifies the expected increase in liter capacity and turns out to be an ideal tool for improving the dynamic parameters of already designed units.

But cars were not the only supporters of it - as early as 1913, locomotive engines with a compressor already existed, and during the First World War, forced charging became an ideal means of compensating for rarefied air in high-altitude aircraft.

(to follow)

Text: Georgy Kolev