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Contact:

Josef Ernst

Telephone: +49 (0) 711-17-7 64 77




Date:
June 2008
The history of the gasoline engine at Mercedes-Benz

The history of the gasoline engine at Mercedes-Benz


  • Unparalleled development of the gasoline engine since the invention of the automobile in 1886

  • Technological potential far from exhausted

The four-stroke gasoline engine was the heart of the first modern automobile designed by Gottlieb Daimler and Carl Benz in 1886. Independently of one another, the two pioneers developed small, high-speed engines, based on Nikolaus Otto’s four-stroke principle, for the drive system of new automobiles. Since the use of these engines in the Benz patent motor car and Daimler’s motor carriage, the four-stroke gasoline engine has experienced unparalleled development.

With their constant innovation, Daimler AG and its predecessor companies have played an important role in the success story of this internal combustion engine for more than 120 years. It was thanks to their tireless work that the single-cylinder power unit of the automobile pioneers became an ultra-modern drive system, especially for passenger cars.

The evolution of the gasoline engine in Mercedes-Benz vehicles is therefore the story of the continuous improvement of numerous details. Even within individual engine series, continuous revision was testament to the pursuit of the perfect engine. Time and again, the engineers increased output and torque on the one hand, and reduced consumption and emissions on the other. This process incorporated both direct results from corporate research and the experience Mercedes-Benz gained from the use of gasoline engines in racing cars.

This history is forever being rewritten, because the Mercedes-Benz engine specialists are not content to sit on their laurels and declare themselves satisfied with one of the high standards that they set for themselves time and again. The current generation of gasoline engines can always be improved further, as has been shown by 125 years of experience. That is how long it has been since Gottlieb Daimler and Wilhelm Maybach resigned from the Deutz engine factory in order to develop their high-speed four-stroke gasoline engine, called the Grandfather Clock because of its appearance. By 1883, the engine had already worked for the first time, and, two years later, Carl Benz’s four-stroke engine was also ready for use. Since these engines publicly powered the world’s first automobiles in 1886, the evolution of gasoline engine technology has progressed with uninterrupted dynamism. The latest example is the new DIESOTTO engine presented in the Mercedes-Benz F 700 research vehicle at the Frankfurt International Motor Show (IAA), which combines the advantages of the gasoline engine with those of the diesel engine.


The development of the gasoline engine


  • A drive system using controlled explosions

  • Gasoline as a fuel used at a later stage

  • Patent for the four-stroke gasoline engine in 1877

The most important power source during the Industrial Revolution was the steam engine. However, these machines were so large and heavy that they were hardly suitable for powering automobiles. This was due in particular to the spatially separated generation and mechanical use of steam. In categories below the railway locomotive and the traction engine, which was principally used in agriculture, no vehicle could be efficiently operated by a steam engine. Of course, there were different models of steam-powered automobiles and trucks. However, the pursuit of an alternative engine for road vehicles as well as for small-scale trades and industry was to become a separate chapter in the history of the steam engine.

A good solution for the engine needs of small companies and crafts businesses appeared to be the direct-action, coal-gas-operated internal combustion engine. The infrastructure for providing such engines was created in the first third of the nineteenth century: in 1807, the world’s first ever gas streetlight was installed in London by way of trial. A few years later, the development of a public coal gas network began in the British capital, and other cities and industrial towns around the world followed suit soon afterwards.



Gas pistols and powder engines

The dream of the internal combustion engine was considerably older than the gas network, however. The Dutch scientist Christiaan Huygens (1629–1695) had already developed an atmospheric engine that operated with gunpowder. In 1673, Huygens demonstrated his powder engine in public. It achieved its task in that the explosion of the powder produced a partial vacuum in the cylinder, and the piston that was shot upwards by the explosion was then pushed down again by the atmosphere. However, Huygens was unable to produce continuous running of the engine from this single ignition.

The principle of the ignition of gas using an electric spark had also been known for a long time. Amongst the predecessors of the modern gasoline engine was the gas pistol, demonstrated in 1776 by the Italian scientist Alessandro Volta (1745–1827). In order to demonstrate the working of electricity, he ignited a mixture of methane and air in a glass cylinder with the aid of an electric spark. The subsequent explosion forced the stopper out of the cylinder.

Lenoir’s gas engine

The world’s first truly viable internal combustion engine was the atmospheric two-stroke gas engine by Jean Joseph Etienne Lenoir (1822–1900). The Luxembourg-born inventor developed his double-acting two-stroke engine in 1859. In the Lenoir engine, the non-compressed mixture of coal gas and air was alternately and electrically ignited on both sides of a disk piston. For the ignition, Lenoir used the spark coil developed by Daniel Ruhmkorff. However, the power was produced not by the explosion of the mixture, but by the atmospheric pressure that counteracted the partial vacuum created by combustion.

In January 1860, Lenoir showed his engine in public for the first time, and it was met with great enthusiasm. In the following years, several hundred engines of this type were built, with an output of between 0.25 hp (0.19 kW) and 4 hp (2.9 kW). Owing to the high operating costs compared with a steam engine with the same output, the Lenoir gas engine was favored primarily in those areas where continuous operation was not required – i.e. where the gas engine was able to make use of its advantage of always being quickly ready for use.

Father of the four-stroke gasoline engine: Nikolaus August Otto

The Lenoir engine also inspired the businessman Nikolaus August Otto (1832–1891) and his brother Wilhelm to experiment with engine design. Shortly after the presentation of the French gas engine, the young men, who were originally from the Taunus area of Germany, began their own experiments to try to build a power machine superior to the Lenoir system. A first patent for the provision of fuel by turning ethyl alcohol to gas was denied the two inventors in Prussia in 1861. From a modern perspective, this rejection seems particularly incomprehensible, since, with this concept, the Otto brothers were already envisaging the use of their engine to power vehicles.

Owing to increasing difficulties, Wilhelm Otto soon withdrew from the engine development business. Nikolaus, however, continued the experiments and had his first model engine built in 1861. It became the “starting point for the four-stroke gas engine,” the inventor reflected in retrospect. In 1862, Otto finally had a four-cylinder trial engine built by Michael Joseph Zons at the mechanical workshop of J. Zons in Cologne. Through the introduction of a new compression stroke during earlier experiments, Otto had worked out the functioning of the four-stroke process, which he now implemented in this model. Every operating cycle of the engine consisted of the following steps: mixture intake, compression, ignition, and discharge of the exhaust gas. This four-stroke engine appears particularly visionary today, since, even then, many of its design-engineering details were similar to those of later engines.

However, the design of the pistons was unusual: each cylinder was equipped with an auxiliary piston. This was intended to minimize the strength of the ignition in that the explosion acted initially on the operating piston which was pressed into the auxiliary piston and compressed the air contained therein. The force thus transmitted was passed on by the auxiliary piston to the crankshaft. The mechanical action was therefore delayed and cushioned by the air. In this way, Otto sought to obtain particularly smooth running. Instead however, the unpredictable action of the auxiliary piston produced very irregular running, and ultimately destroyed the trial engine.



Move away from the direct-acting four-cylinder engine

As a result of these problems, Otto decided to build an atmospheric engine. In an atmospheric internal combustion engine, the explosion did not damage the mechanics because the pressure of the explosion moved the piston upwards. However, a mechanical linkage to the powertrain was produced only at top dead center. After the cooling of the combustion gases in the cylinder, the atmospheric pressure and the weight of the piston generated the power.

The structure again contained an auxiliary piston. When the gas-air mixture was ignited, the explosion initially shot the operating piston upwards, the latter connected via a hollow piston rod to the auxiliary piston. Both pistons were now mechanically coupled. The atmospheric pressure thus acted on both pistons and generated power in that it forced the operating and auxiliary pistons to the floor. At bottom dead center, the pistons were released from one another, and the auxiliary piston rose up again because of the inertia of the flywheel. There, the operating piston contacted it after the next explosion. With his complex arrangement, Nikolaus Otto obtained the intended separation of the drive shaft from the impact of the explosions.

Mechanical engineering company N. A. Otto & Cie.

When Otto had this engine patented, he had hardly any funds left. In this time of financial need, help was provided through contact with the Cologne-based engineer Eugen Langen whom he met in 1864. The two men founded the mechanical engineering company N. A. Otto & Cie., in which Langen was a limited partner. Eugen Langen also contributed to the success of the business as an engineer. He developed the freewheel clutch, which was necessary for a smooth change between the power transmission, during the action of the atmospheric pressure, from the toothed rack of the auxiliary pistons to the driveshaft, and the freewheeling after the ignition of the mixture. In 1866, for the thus amended engine, Otto was finally granted the coveted Prussian patent – his original design had been patented only elsewhere in Europe.

At the World Exhibition in Paris in 1867, Otto’s engine was favored over Lenoir’s engine and other gas engines. After measuring the gas consumption, the jury even awarded the “Grand Prix” to the German engine because Otto’s engine required less than half the gas of other engines. This international approval was the basis for production on a larger scale, and brought the company economic stability. As well as the incorporation of the company, in 1872 the name was changed to Gasmotoren-Fabrik Deutz AG (Deutz Gas Engine Factory). In 1872, Gottlieb Daimler was appointed member of the directorate of Gasmotoren-Fabrik Deutz AG, a company which had emerged from N. A. Otto & Cie. Daimler also brought the design engineer Wilhelm Maybach with him to Otto. In 1875, Maybach was already attempting to convert the atmospheric engine to gasoline operation. His first success was obtained with a wad of rags soaked in gasoline, which he held in front of the engine’s gas supply.

Development of the direct-acting four-stroke engine

For Nikolaus Otto, however, the improvement of the engine itself was more urgent than the development of an alternative source of fuel using gasoline, since the design of the atmospheric engine limited the engine’s output to a maximum of 3 hp (2.2 kW) as long as the dimensions had to remain in a context that catered to the crafts and small businesses. Hot-air engines by other manufacturers at this time were already reaching up to 8 hp (5.9 kW). In 1876, Otto therefore developed a direct-acting four-stroke gas engine with pre-compression of the charge, which achieved 3 hp (2.2 kW) at 180 rpm. In the process, he adopted the flame ignition and slide valve gear from the atmospheric gas engine. Wilhelm Maybach improved this engine. Parallel to the development of the four-stroke engine, atmospheric gas engines were still being built in Deutz. The last of these engines was purchased by a customer only after 1900.

In 1877, Nikolaus Otto was granted German Reich Patent No. 532 for his engine. In particular, he had the so-called stratified charge patented: he assumed that the smooth and uniform ignition depended on the distribution of mixture concentration in the cylinder. Otto mentioned his revolutionary invention of the four-stroke process, as is still used today, only under Item 4 of the patent. He had not even recognized the significance of this invention himself at the time.

Multi-cylinder engines by Deutz

The basis for Nikolaus Otto’s “twin engine” in 1879 was two parallel-mounted four-stroke single-cylinder engines that had ignitions displaced at 360 degrees, and that acted together on a crankshaft. This very smoothly running engine powered in particular dynamos that supplied electrical energy for lighting.

In the same year, Gottlieb Daimler designed the “Deutz compound engine,” which operated with two high-pressure cylinders and one low-pressure cylinder. In mechanical terms, this construction corresponded to the connecting of two four-stroke single-cylinder units with one two-stroke single-cylinder. Owing to its inefficiency, the one engine that was delivered to a customer for test purposes was repossessed by Deutz in 1884 as unworkable, and was scrapped in 1925.

Mobility for the gasoline engine

By around 1880, the gasoline engine with flame ignition had become established as a stationary engine for many applications. This internal combustion engine became the basis of modern engine technology. However, its use was still restricted to stationary operation. Then, in 1880, a railway car with a stationary gasoline engine as drive system was created at Hannoversche Maschinenbau AG (Hanomag). The engine, weighing approximately one ton, had also been converted from gas to gasoline operation, and was mounted on a tractor unit for streetcars. For road vehicles, however, the 3-hp (2.2-kW) single-cylinder engine was still too heavy.

In 1884, Nikolaus Otto developed a magneto-electric low-voltage impulse ignition for slow-running stationary engines. This made operation with gasoline simpler, and above all safer, than with spark ignition. Although this ignition device was heavy and expensive, it proved to be very reliable. Because Otto did not patent the contact-breaking ignition, the technology was also used by rival companies; for example, Maybach’s racing car built in 1900 also had a low-voltage impulse ignition.

Cancellation of Otto’s patent

Hanomag pursued an action for annulment against Otto’s patent for the first time in 1882. Hanomag’s principal argument was the stratified charge of the mixture emphasized by Otto: this alleged prerequisite for the smooth running of a four-stroke engine had, in the meantime, been found to be incorrect. In 1886, the Supreme Court of the German Reich found against Nikolaus Otto, and the patent was cancelled. Other companies could now officially build engines with four- and two-stroke working processes in designs that were previously protected by the Deutz patent. This legal ruling allowed dramatic growth in the engine industry in a short period of time.

Otto’s pioneering technological achievements should in no way be underestimated from a modern perspective as a result of the legal ruling of 1886. With his engine, he undoubtedly paved the way for developments such as the Daimler and Benz automobiles, and these two automotive pioneers themselves openly built on Nikolaus Otto’s work as they were convinced of the technological merits. In doing so, from the beginning, Benz focused on the efficient integration of the drive system into a road vehicle, while Daimler worked primarily on a universal engine with which he sought to power as many different means of transport as possible. The idea of mobility by means of the four-stroke gasoline engine was realized by both pioneers, although their solutions differed in their details.

Many years later, in 1996, Nikolaus August Otto and Wilhelm Maybach were honored for their achievements in engineering and automotive technology: the two pioneers were inducted into the Automotive Hall of Fame.




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