Inspirator and Pulverizer
On November 15th, 1887, in London, Edward Butler submitted a patent application covering his invention that he later referred as "atomizer" or "inspirator". On February 11th, 1893, in Budapest, Donát Bánki and János Csonka jointly submitted a patent application covering their invention that they called “carburator“ or “porlasztó”, translated into English as “pulverizer”.
All three of these inventors worked at what was then the cutting edge of modern technology, each with several patents to his credit. Both the inspirator and the pulverizer were conceived to allow gas motors to be operated by liquid fuels. In the following we compare the inspirator and the pulverizier, to see how their design, their purpose, and operation were similar, and how they differed from each other.
In the late 19th it was well known that engines or motors could operate only when the piston was pushed by the expansion of a gas (not a liquid). Many contemporary engineers worked to solve the problem of how to use liquid fuel with gas engines. It seemed perfectly obvious to them that the liquid had to be evaporated before it entered the engine; indeed, that was how steam engines worked: they were powered not by water, but steam.
As a result, a bewildering variety of devices were constructed to accomplish the required evaporation. These devices usually relied on heating the liquid in order to speed evaporation, and were collectively known as “carburators”, or evaporators. They were mostly clumsy (some were larger than the engine itself), unreliable, and because they involved heating a flammable fuel, they amounted to a major fire hazard. All three inventors mentioned above set themselves the task to replace the various carburators then known, with a more practical and safer device.
It was clearly understood at the time that a given volume of liquid will evaporate faster, if it has a larger surface area through which the evaporation can take place. All three inventors also knew that when a given volume of liquid is decomposed into small droplets, its total surface area can increase dramatically. Both the inspirator and the pulverizer were designed to take advantage of these facts, by trying a novel approach, namely, dispersing the liquid fuel into small droplets. To this extent the two inventions were similar.
However, they also differed in certain ways, some of the more important differences will be discussed below.
E. Butler’s goal was the traditional one, namely to have the liquid fuel evaporated, i.e. volatilized as completely as possible before it reaches the piston. He viewed the production of droplets as only the first step, that makes it possible to speed up the subsequent evaporation without excessive heating. To complete the volatilization, he envisioned several imaginative design components. Those included a piston valve creating radially distributed fuel sprays; a chamber in which spray and air are mixed while circulating, thereby also enhancing evaporation; fuel sprays distributed on the surface of a cone; spray passing through sheets of gauze saturated with liquid fuel; generating an annular spray, spray led through externally heated pipes, not only to avoid condensation, but also to enhance evaporation, and so on. Eventually he reached his goal, as stated in the description of his tricycle: “The mixture of air and oil spray formed in the atomizer is volatilized before distribution to the cylinders.” E. Butler knew that fuel efficiency will be higher if the evaporation is more complete, and evidently one of his principal design goals was to optimize fuel efficiency. But there was a price to pay for high fuel efficiency. Added design components make devices more complex, more expensive, and usually heavier. More complexity implies that more things can go wrong in more ways, which in turn makes devices more vulnerable, less reliable, and repairs more difficult.
J. Csonka and D. Bánki chose a different approach. Their design was based on the important insight that it is not necessary to strive for the complete evaporation of the liquid fuel, and thereby achieve optimal fuel efficiency, instead, their principal design goal was simplicity. In fact, they broke with tradition, and preferred to work with a medium that was a mixture of air and liquid droplets, i.e. the spray itself. In today’s language we can say that they chose to work with a “macromolecular gas”, in which the “macromolecules” were liquid droplets. Such a medium in many ways resembles an ordinary (molecular) gas. In particular, it can be injected directly into the motor cylinder, just as ordinary gases can.
Since the evaporation was incomplete, this novel approach implied lower fuel efficiency. But these inventors were willing to accept that trade-off, because at that price they were able to create a simpler, lighter, cheaper device, one that had fewer ways of breaking down, therefore was more reliable, and was easier to repair.
Speaking of reliability, it is worth pointing out that the experimental engine to which the first ever pulverizer belonged, was tracked down after more than 50 years of service, and at that time it was placed in a museum. In the meanwhile it had been sold and resold to different owners 12 times, nevertheless the engine, and with it the original pulverizer, were still in good working order (!), and, amazingly, the pulverizer still contained its original cork-float. (Later models used floaters made of copperplate or synthetic material.)
E. Butler intended his device to be used primarily on moving engines. As he himself stated: on “tricycles and other light vehicles.” He seems to have given little thought to operating the inspirator in conjunction with static engines. This was not an unreasonable position to take. The technology of static gas motors of his day was mature, and well understood. There was less urgent need for a change in this area. On the other hand, the construction and operation of mobile gas motors remained a virtually unsurmountable obstacle, E. Butler intended to overcome that obstacle with his invention, the inspirator. However, when his tricycle business failed (ostensibly, because in England the authorities imposed a 4 mi//hr speed limit on self energized vehicles), he broke up his tricycle, and sold it as scrap metal. He also sold his inspirator patent to one who hoped to build engines for motor boats. Thereafter E. Butler lost interest in the inspirator, and went on to occupy himself with other matters. The inspirator remained unknown on the European continent.
On the other hand, right from the start, D. Bánki and J.Csonka planned to use their pulveriser with both static and mobile hydrocarbon engines. They fully appreciated the opportunities opened up by liquid fuel for both types of engines. Indeed, after the first working pulverizer was constructed, J. Csonka not only incorporated such a device into every engine that he designed or built himself, whether static or mobile, but did so until the end of his life almost half a century later. And after his passing, that practice was continued by the machine factory he founded.
Largely because of its simplicity and reliability, and also as a result of the activities of the German engineers Wilhelm Maybach, the French Longuemare factory, the creators of the Solex and Zenith systems, and many others, including its two co-inventors, the pulverizer eventually spread all over the European continent, and later to every corner of the world. Despite their great variety, the working principle of carburators even today is the same as was patented by D. Bánki and J. Csonka in 1893. It helped to usher in the age of motorized long distance travel, the world of cars, trucks, buses, and airplanes, of super highways and airports, in short, the modern world as we know it.