Diesel's first experimental engine 1893
The definition of a diesel engine to many has become an engine that uses compression ignition. To some it may be an engine that uses heavy fuel oil; to others it is an engine that does not use spark ignition. However, the original cycle proposed by Rudolf Diesel in 1892 was a constant temperature cycle (a cycle based on the Carnot theory) that would require much higher compression than what is needed for compression ignition. Diesel's idea was to compress the air so tightly that the temperature of the air would exceed that of combustion. In his 1892 US patent (granted in 1895) #542846 Diesel describes the compression required for his cycle:
- "pure atmospheric air is compressed, according to curve 1 2, to such a degree that, before ignition or combustion takes place, the highest pressure of the diagram and the highest temperature are obtained-that is to say, the temperature at which the subsequent combustion has to take place, not the burning or igniting point. To make this more clear, let it be assumed that the subsequent combustion shall take place at a temperature of 700°. Then in that case the initial pressure must be sixty-four atmospheres, or for 800° centigrade the pressure must be ninety atmospheres, and so on. Into the air thus compressed is then gradually introduced from the exterior finely divided fuel, which ignites on introduction, since the air is at a temperature far above the igniting-point of the fuel. The characteristic features of the cycle according to my present invention are therefore, increase of pressure and temperature up to the maximum, not by combustion, but prior to combustion by mechanical compression of air, and there upon the subsequent performance of work without increase of pressure and temperature by gradual combustion during a prescribed part of the stroke determined by the cut-oil".
In later years Diesel realized his original cycle would not work and he adopted the constant pressure cycle. Diesel describes the cycle in his 1895 patent application. Notice that there is no longer a mention of compression temperatures exceeding the temperature of combustion. Now all that is mentioned is the compression must be high enough for ignition.
- "1. In an internal-combustion engine, the combination of a cylinder and piston constructed and arranged to compress air to a degree producing a temperature above the igniting-point of the fuel, a supply for compressed air or gas; a fuel-supply; a distributing-valve for fuel, a passage from the air supply to the cylinder in communication with the fuel-distributing valve, an inlet to the cylinder in communication with the air-supply and with the fuel-valve, and a cut-oil, substantially as described." See US patent # 608845 filed 1895 / granted 1898
History shows that the invention of the diesel engine was not based solely on one man's idea, but was the culmination of many different ideas that were developed over time.
In 1806, brothers Claude and Nicéphore Niépce developed the first known internal combustion engine and the first fuel injection system. The Pyréolophore fuel system used a blast of air provided by a bellows to atomize Lycopodium (a highly combustible fuel made from broad moss). Later coal dust mixed with resin became the fuel. Finally in 1816 they experimented with alcohol and white oil of petroleum (a fuel similar to kerosene). They discovered that the kerosene-type fuel could be finely vaporized by passing it through a reed type device, making the fuel highly combustible.
In 1874, George Brayton developed and patented a two-stroke, oil-fueled, constant-pressure engine called "The Ready Motor". This engine used a metered pump to supply fuel to an injection device in which the oil was vaporized by air and burned as it entered the cylinder. These were some of the first practical internal combustion engines to supply motive power. Brayton's engines were installed in several boats, a rail car, two submarines and a bus. Diesel engine also operate on a similar "constant pressure" cycle.
Throughout the 1880s, Brayton continued trying to improve his engines. In 1887, he developed and patented a four-stroke, direct-injection oil engine (US patent #432,114 of 1890, application filed in 1887). The fuel system used a variable quantity pump and liquid-fuel, high-pressure, spray-type injection. The liquid was forced through a spring-loaded relief type valve (injector) which caused the fuel to become divided into small droplets (vaporized). Injection was timed to occur at or near the peak of the compression stroke. A platinum ignitor provided the source of ignition. Brayton described the invention as follows: "I have discovered that heavy oils can be mechanically converted into a finely-divided condition within a firing portion of the cylinder, or in a communicating firing chamber." He continued, "I have for the first time, so far as my knowledge extends, regulated speed by variably controlling the direct discharge of liquid fuel into the combustion chamber or cylinder into a finely-divided condition highly favorable to immediate combustion". This was likely the first engine to use a lean-burn system to regulate engine speed/output. In this manner the engine fired on every power stroke and speed/output was controlled solely by the quantity of fuel injected.
In 1890, Brayton developed and patented a four-stroke, air-blast oil engine (US patent #432,260). The fuel system delivered a variable quantity of vaporized fuel to the center of the cylinder under pressure at or near the peak of the compression stroke. The ignition source was an igniter made from platinum wire. A variable-quantity injection pump provided the fuel to an injector, where it was mixed with air as it entered the cylinder. A small crank-driven compressor provided the air source. This engine also used the lean-burn system.
Brayton died in 1893, but would be credited with the invention of the constant-pressure Brayton cycle.
In 1885, the English inventor Herbert Akroyd Stuart began investigating the possibility of using paraffin oil (very similar to modern-day diesel) for an engine, which unlike petrol would be difficult to vaporise in a carburetor as its volatility is not sufficient to allow this.
The hot bulb engines, first prototyped in 1886 and built from 1891 by Richard Hornsby and Sons, used low pressure fuel injection system. The Hornsby-Akroyd oil engine used a comparatively low compression ratio, so that the temperature of the air compressed in the combustion chamber at the end of the compression stroke was not high enough to initiate combustion. Combustion instead took place in a separated combustion chamber, the "vaporizer" or "hot bulb" mounted on the cylinder head, into which fuel was sprayed. Self-ignition occurred from contact between the fuel/air mixture and the hot walls of the vaporizer. As the engine's load increased, so did the temperature of the bulb, causing the ignition period to advance; to counteract pre-ignition, water was dripped into the air intake.
In 1892, Akroyd Stuart patented a water-jacketed vaporizer to allow compression ratios to be increased but primarily to reduce auto-ignition problems at higher loads and compression ratios. In the same year, Thomas Henry Barton at Hornsbys built a working high-compression version for experimental purposes, whereby the vaporizer was replaced with a cylinder head, therefore not relying on air being preheated, but by combustion through higher compression ratios. It ran for six hours—the first time automatic ignition was produced by compression alone; however, such a claim is not substantiated by any source. Until 1907, hotbulb engines were supposed to be charged with fuel at the intake stroke, although separately from air. Such an engine would have been prone to failure, poor performance or extreme malfunctioning due to pre-ignition. 
Herbert Akroyd Stuart was a pioneer in developing compression ignition aided by retained heat of combustion in the bulb, Rudolf Diesel however, was subsequently credited with the true compression ignition engine relying solely on heat of compression and not any other form of retained heat. Higher compression and thermal efficiency along with injection timing of fuel and vaporization of fuel through injection system and not by heated surface is what distinguishes Diesel's patent of 3,500 kilopascals (508 psi).
In 1892, Diesel received patents in Germany, Switzerland, the United Kingdom and the United States for "Method of and Apparatus for Converting Heat into Work". In 1893, he described a "slow-combustion engine" that compressed air, thereby raising its temperature above the ignition point of the fuel, then gradually introducing fuel while letting the mixture expand "against resistance sufficiently to prevent an essential increase of temperature and pressure", then cutting off fuel and "expanding without transfer of heat". In 1894 and 1895, he filed patents and addenda in various countries for his engine; the first patents were issued in Spain (No. 16,654), France (No. 243,531) and Belgium (No. 113,139) in December 1894, and in Germany (No. 86,633) in 1895 and the United States (No. 608,845) in 1898. He operated his first successful engine in 1897.
On February 17, 1894, the redesigned engine ran for 88 revolutions - one minute; with this news, Maschinefabrik Augsburg's stock rose by 30%, indicative of the tremendous anticipated demands for a more efficient engine. Diesel rushed to complete a working prototype in 1896 in order to maintain the patent. The first engine ready for testing was built on December 31, 1896 (though it was much different engine than the one he had started with). In 1897 — between deal signingpipelines, electric and water plants, automobiles and trucks, and marine craft. They were soon used in mines, oil fields, factories, and transoceanic shipping.
and brainstorming episodes — he completed an engine which ran 16.93 kW with an efficiency of 16.6%. Diesel was granted the patent and by 1898, had become a millionaire. His engines were used to power
- 1806 The Pyréolophore uses the first fuel injection system and is used for powering a boat. In 1807 is granted a patent.
- 1874 George Brayton's constant pressure "Ready Motor" uses a metered fuel pump and burns oil fuel inside the cylinder.
- 1886: Herbert Akroyd Stuart builds a prototype hot bulb engine.
- 1887 George Brayton builds an engine that uses a spring loaded injector and solid metered injection system (lean burn combustion).
- 1890 George Brayton builds an "Air Blast" injection engine with a lean burn system.
- 1891: Herbert Akroyd Stuart patents an internal combustion engine that uses a "hot bulb" and pressurized fuel injection.
Akroyd Stuart builds his first working diesel engine.
- 1893: Rudolf Diesel's essay titled Theory and Construction of a Rational Motor appeared.
- 1893: February 23, Rudolf Diesel obtained a patent (RP 67207) titled "Arbeitsverfahren und Ausführungsart für Verbrennungsmaschinen" (Working Methods and Techniques for Internal Combustion Engines).
- 1893: August 10, Diesel built his first prototype in Augsburg, This engine never ran under its own power.
- 1894 Diesel's second prototype runs for the first time.
- 1895 Diesel applies for a second patent US Patent # 608845
- 1896 Blackstone & Co, a Stamford farm implement they built lamp start oil engines.
- 1897: Adolphus Busch licenses rights to the diesel engine for the US and Canada.
- 1897: After 4 years Diesel's prototype engine is running and finally ready for efficiency testing and production.
- 1898: Diesel licensed his engine to Branobel, a Russian oil company interested in an engine that could consume non-distilled oil. Branobel's engineers spent four years designing a ship-mounted engine.
- 1899: Diesel licensed his engine to builders Krupp and Sulzer, who quickly became major manufacturers.
- 1902: Until 1910, MAN produced 82 copies of the stationary diesel engine.
- 1903: Two first diesel-powered ships were launched, both for river and canal operations:
La Petite-Pierre in France, powered by Dyckhoff-built diesels, and Vandal tanker in Russia, powered by Swedish-built diesels with an electrical transmission.
- 1904: The French built the first diesel submarine, the Z.
- 1905: Four diesel engine turbochargers and intercoolers were manufactured by Büchi (CH), as well as a scroll-type supercharger from Creux (F) company.
- 1908: Prosper L'Orange and Deutz developed a precisely controlled injection pump with a needle injection nozzle.
- 1909: The prechamber with a hemispherical combustion chamber was developed by Prosper L'Orange with Benz.
- 1910: The Norwegian sailing research ship Fram was fitted with an auxiliary diesel engine, and was thus the first ocean-going ship with a diesel engine. The Dutch tanker Vulcanus became the first ocean-going ship exclusively powered by a diesel engine.
- 1912: The Danish built MS Selandia, the most advanced ocean-going diesel motor ship in her time. The first locomotive with a diesel engine also appeared.
- 1913: US Navy submarines used NELSECO units. Rudolf Diesel died mysteriously when he crossed the English Channel on the SS Dresden.
- 1914: German U-boats were powered by MAN diesels.
- 1919: Prosper L'Orange obtained a patent on a prechamber insert and made a needle injection nozzle. First diesel engine from Cummins.
One of the eight-cylinder 3200 I.H.P. Harland and Wolff—Burmeister & Wain diesel engines installed in the motorship Glenapp
. This was the highest powered diesel engine yet (1920) installed in a ship. Note man standing lower right for size comparison.
- 1921: Prosper L'Orange built a continuous variable output injection pump.
- 1922: The first vehicle with a (pre-chamber) diesel engine was Agricultural Tractor Type 6 of the Benz Söhne agricultural tractor OE Benz Sendling.
- 1923: The first truck with pre-chamber diesel engine made by MAN and Benz. Daimler-Motoren-Gesellschaft testing the first air-injection diesel-engined truck.
- 1924: The introduction on the truck market of the diesel engine by commercial truck manufacturers in the IAA. Fairbanks-Morse starts building diesel engines.
- 1924-1925 Fairbanks Morse introduced the 2 stroke Y-VA and Model 32. It was the first cold start diesel manufactured by Fairbanks and would become an icon of American industrial power.
- 1927: First truck injection pump and
injection nozzles of Bosch. First passenger car prototype of Stoewer.
- 1930s: Caterpillar started building diesels for their tractors.
- 1930: First US diesel-power passenger car (Cummins powered Packard) built in Columbus, Indiana (US).
- 1930: Beardmore Tornado diesel engines power the British airship R101.
- 1932: Introduction of the strongest diesel truck in the world by MAN with 160 hp (120 kW).
- 1933: First European passenger cars with diesel engines (Citroën Rosalie); Citroën used an engine of the English diesel pioneer Sir Harry Ricardo. The car did not go into production due to legal restrictions on the use of diesel engines.
- 1933: Yanmar is the first Japanese company to introduce the "HB" series for commercial use.
- 1933: General Motors uses its new roots-blown, unit-injected two-stroke Winton 201A Diesel engine to power its automotive assembly exhibit at the Chicago World's Fair (A Century of Progress). The engine represented a major improvement in power-to-weight ratio and output flexibility over previous generation diesels, drawing the interest of railroad executiveRalph Budd as a prime mover for lightweight trains.
- 1934: The Budd Company builds the first streamlined, stainless steel passenger train in the US, the Pioneer Zephyr, using a Winton engine.
- 1934: First turbo diesel engine for a railway train by Maybach. First streamlined, stainless steel passenger train in the US, the Pioneer Zephyr, using a Winton engine.
- 1934: First tank equipped with diesel engine, the Polish 7TP.
- 1934–35: Junkers Motorenwerke in Germany started production of the Jumo aviation diesel engine family, the most famous of these being the Jumo 205, of which over 900 examples were produced by the outbreak of World War II.
- 1936: Mercedes-Benz built the 260D diesel car. AT&SF inaugurated the diesel train Super Chief. The airship Hindenburg was powered by diesel engines. First series of passenger cars manufactured with diesel engine (Mercedes-Benz 260 D, Hanomag and Saurer). Daimler Benz airship diesel engine 602LOF6 for the LZ129 Hindenburg airship.
- 1937: The Soviet Union developed the Kharkiv model V-2 diesel engine, later used in the T-34 tanks, widely regarded as the best tank chassis of World War II.
- 1937: BMW 114 experimental airplane diesel engine development.
- 1938: General Motors forms the GM Diesel Division, later to become Detroit Diesel, and introduces the Series 71 inline high-speed medium-horsepower two stroke engine, suitable for road vehicles and marine use.
- 1938: GM introduces the 567 two stroke medium-speed high-horsepower engine for locomotive, ship and stationary applications; These engines utilize GM's patented Unit injector. The 567 established the reliability of diesel power in rail service, lending impetus to the dieselization of American railroads.
- 1938: First turbo diesel engine of Saurer.
- 1953: Turbo-diesel truck for Mercedes in small series.
- 1954: Turbo-diesel truck in mass production by Volvo. First diesel engine with an overhead cam shaft of Daimler Benz.
- 1958 EMD introduces turbocharging for its 567 series of medium speed, high horsepower locomotive, stationary and marine engines. Every subsequent engine (645 and 710) would incorporate this turbocharger.
- 1973: DAF produced an air-cooled diesel engine.
- 1976 February: Tested a diesel engine for the Volkswagen Golf passenger car. The Cummins Common Rail injection system was further developed by the ETH Zurich from 1976 to 1992.
- 1978: Mercedes-Benz produced the first passenger car with a turbo-diesel engine (Mercedes-Benz 300 SD). Oldsmobile introduced the first passenger car diesel engine produced by an American car company.
- 1979: Peugeot 604, the first turbo-diesel car to be sold in Europe.
- 1985: ATI Intercooler diesel engine from DAF. European Truck Common Rail system with the IFA truck type W50 introduced.
- 1986: BMW 524td, the world's first passenger car equipped with an electronically controlled injection pump (developed by Bosch). The same year, the Fiat Croma was the first passenger car in the world to have a direct injection (turbocharged) diesel engine.
- 1987: Most powerful production truck with a 460 hp (340 kW) MAN diesel engine.
- 1989: Audi 100, the first passenger car in the world with a turbocharged direct injection and electronic control diesel engine.
- 1991: European emission standards Euro 1 met with the truck diesel engine of Scania.
- 1993: Pump nozzle injection introduced in Volvo truck engines.
- 1994: Unit injector system by Bosch for diesel engines. Mercedes-Benz unveils the first automotive diesel engine with four valves per cylinder. Medium speed high horsepower locomotive, ship and stationary diesel engines have utilized four valves per cylinder since at least 1938.
- 1995: First successful use of common rail in a production vehicle, by Denso in Japan, Hino "Rising Ranger" truck.
- 1996: First diesel engine with direct injection and four valves per cylinder, used in the Opel Vectra.
- 1997: First common rail diesel engine in a passenger car, the Alfa Romeo 156.
- 1998: BMW made history by winning the 24 Hours Nürburgring race with the 320d, powered by a two-litre, four-cylinder diesel engine. The combination of high-performance with better fuel efficiency allowed the team to make fewer pit stops during the long endurance race. Volkswagen introduces three and four-cylinder turbodiesel engines, with Bosch-developed electronically controlled unit injectors. Smart presented the first common rail three-cylinder diesel engine used in a passenger car (the Smart City Coupé).
- 1999: Euro 3 of Scania and the first common rail truck diesel engine of Renault.
- 2002: A street-driven Dodge Dakota pickup with a 735 horsepower (548 kW) diesel engine built at Gale banks engineering hauls its own service trailer to the Bonneville Salt Flats and set an FIA land speed record as the world's fastest pickup truck with a one-way run of 222 mph (357 km/h) and a two-way average of 217 mph (349 km/h).
- 2003: Piezoelectric injector technology by Bosch, Siemens and Delphi.
- 2004: In Western Europe, the proportion of passenger cars with diesel engine exceeded 50%. Selective catalytic reduction (SCR) system in Mercedes, Euro 4 with EGR system and particle filters of MAN. Audi A8 3.0 TDI is the first production vehicle in the world with common rail injection and piezoelectric injectors.
- 2006: Audi R10 TDI won the 12 Hours of Sebring and defeated all other engine concepts. The same car won the 2006 24 Hours of Le Mans. Euro 5 for all Iveco trucks. JCB Dieselmax broke the FIA diesel land speed record from 1973, eventually setting the new record at over 350 mph (563 km/h).
- 2007: Lombardini develops a new 440 cc twin-cyinder common rail diesel engine, which two years later sees application in automotive use, in the Ligier microcars. At the time, this engine was considered to be the smallest twin-cyinder engine with a common rail system.
- 2008: Subaru introduced the first horizontally opposed diesel engine to be fitted to a passenger car. This is a Euro 5 compliant engine with an EGR system. SEAT wins the drivers' title and the manufacturers' title in the FIA World Touring Car Championship with the SEAT León TDI. The achievements are repeated in the following season.
- 2009: Volkswagen won the 2009 Dakar Rally held in Argentina and Chile. The first diesel to do so. Race Touareg 2 models finished first and second. The same year, Volvo is claimed the world's strongest truck with their FH16 700. An inline 6-cylinder, 16 L (976 cu in) 700 hp (522 kW) diesel engine producing 3150 Nm (2323.32 lb•ft) of torque and fully complying with Euro 5 emission standards.