Two stroke diesel
Encyclopedia
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
that works in two strokes. A diesel engine is an internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...
which operates using the Diesel cycle
Diesel cycle
The Diesel cycle is the thermodynamic cycle which approximates the pressure and volume of the combustion chamber of the Diesel engine, invented by Rudolph Diesel in 1897. It is assumed to have constant pressure during the first part of the "combustion" phase...
. Invented in 1892 by German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
engineer Rudolf Diesel
Rudolf Diesel
Rudolf Christian Karl Diesel was a German inventor and mechanical engineer, famous for the invention of the diesel engine.-Early life:Diesel was born in Paris, France in 1858 the second of three children of Theodor and Elise Diesel. His parents were Bavarian immigrants living in Paris. Theodor...
, it was based on the hot bulb engine
Hot bulb engine
The hot bulb engine, or hotbulb or heavy oil engine is a type of internal combustion engine. It is an engine in which fuel is ignited by being brought into contact with a red-hot metal surface inside a bulb....
design and patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
ed on February 23, 1893. During the period of 1900 to 1930, four-stroke diesel engines enjoyed a relative dominance in practical diesel applications. Charles F. Kettering and colleagues, working at the various incarnations of Electro-Motive and at the General Motors Research Corporation during the 1930s, advanced the art and science of two-stroke diesel technology to yield engines with much higher power-to-weight ratio
Power-to-weight ratio
Power-to-weight ratio is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement of actual performance of any engine or power sources...
s than the two-stroke diesels of old. This work was instrumental in bringing about the dieselisation
Dieselisation
Dieselisation or dieselization is a term generally used for the increasingly common use of diesel fuel in vehicles, as opposed to gasoline or steam engines.-Water Transport:...
of railroads in the 1940s and 1950s.
All diesel engines use compression ignition, a process by which fuel is injected after the air is compressed in the combustion chamber causing the fuel to self ignite
Self-ignition
Self-ignition can refer either to*Spontaneous combustion or*the ability of Diesel fuel to ignite under high compression and the use of that phenomenon in Diesel engines...
. By contrast, gasoline engines utilize the Otto cycle
Otto cycle
An Otto cycle is an idealized thermodynamic cycle which describes the functioning of a typical reciprocating piston engine, the thermodynamic cycle most commonly found in automobile engines....
, in which fuel and air are mixed before entering the combustion chamber and then ignited by a spark plug
Spark plug
A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed fuels such as aerosol, gasoline, ethanol, and liquefied petroleum gas by means of an electric spark.Spark plugs have an insulated central electrode which is connected by...
.
Two strokes
Two-stroke internal combustion engines are more simple mechanically than four-stroke engines, but more complex in thermodynamic and aerodynamic processes. In a two-stroke engine, the four "cycles" of internal combustion engine theory (intake, compression, ignition, exhaust) occur in one revolution, while in a four-stroke engine it occurs in two complete revolutions. In a two-stroke engine, more than one function occurs at any given time during the engine's operation.- Intake begins when the piston is near the bottom dead center. Air is admitted to the cylinder through ports in the cylinder wall (there are no intake valves). All two-stroke Diesel engines require artificial aspiration to operate, and will either use a mechanically-driven blower or a hybrid turbo-supercharger to charge the cylinder with air. In the early phase of intake, the air charge is also used to force out any remaining combustion gases from the preceding power stroke, a process referred to as scavengingScavenging (automotive)In automotive usage, scavenging is the process of pushing exhausted gas-charge out of the cylinder and drawing in a fresh draught of air ready for the next cycle....
. - As the piston rises, the intake charge of air is compressed. Near top dead center, fuel is injected, resulting in combustion due to the extremely high pressure and heat created by compression, which drives the piston downward. As the piston moves downward in the cylinder it will reach a point where the exhaust port is opened to expel the high-pressure combustion gasses. However, most current two-stroke diesel engines use top-mounted poppet valvePoppet valveA poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide...
s and uniflowUniflowUniflow may refer to:* Uniflow diesel engine* Uniflow steam engine* UniFLOW Output Manager...
scavenging. Continued downward movement of the piston will expose the air intake ports in the cylinder wall, and the cycle will start again.
Roots blower
The Roots blower is commonly used on the two stroke diesel engine, which requires some form of forced inductionForced induction
Forced induction is the process of compressing air on the intake of an internal combustion engine . A forced induction engine uses a gas compressor to increase the pressure, temperature and density of the air...
. In this application, the blower does not provide significant compression and these engines are considered naturally aspirated
Naturally-aspirated engine
A naturally aspirated engine is one common type of reciprocating piston internal combustion engine that depends solely on atmospheric pressure to counter the partial vacuum in the induction tract to draw in combustion air...
; turbocharger
Turbocharger
A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...
s are generally used when significant "boost
Boost
-Science, technology and mathematics:* Automotive:** Boost, positive manifold pressure in cars, see Turbocharger#Pressure increase.*** a loose term for turbo or supercharger** A slang term meaning to start a vehicle, see jump start...
" is needed.
Notable manufacturers
- WärtsiläWärtsiläWärtsilä is a Finnish corporation which manufactures and services power sources and other equipment in the marine and energy markets. The core products of Wärtsilä include large combustion engines...
, two-stroke crosshead diesel engines for marine propulsion - MAN Diesel & TurboMAN Diesel & TurboMAN Diesel & Turbo SE is multinational company based in Germany that produces large-bore diesel engines for railway-locomotives, marine propulsion systems, power plant applications and turbochargers. The company was formed in 2010 from the merger of MAN Diesel and MAN Turbo...
, crosshead diesel engines for marine propulsion - Mitsubishi Heavy IndustriesMitsubishi Heavy Industries, or MHI, is a Japanese company. It is one of the core companies of Mitsubishi Group.-History:In 1870 Yataro Iwasaki, the founder of Mitsubishi took a lease of Government-owned Nagasaki Shipyard. He named it Nagasaki Shipyard & Machinery Works, and started the shipbuilding business on a full scale...
, crosshead diesel engines for marine propulsion - Electro-Motive Diesel, two-stroke uniflow diesel generators for railway and stationary applications
- Detroit DieselDetroit DieselAs a corporation, Daimler Trucks North America has decided to rename the company "DETROIT".Detroit Diesel Corporation is an American-based diesel engine producer headquartered in Detroit, Michigan, USA...
, two-strokes uniflow - Rootes Group, the Commer TS3Commer TS3The Commer TS3 was a diesel engine fitted in Commer trucks built by the Rootes Group in the 1950s and 1960s. It was largely the product of Tilling-Stevens, but was developed by Rootes Group when they bought out Tilling-Stevens...
engine for trucks