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Two-stroke
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes of the piston, one up and one down, in one revolution of the crankshaft in contrast to a four-stroke engine which requires four strokes of the piston in two crankshaft revolutions to complete a power cycle. During the stroke from bottom dead center to top dead center, the end of the exhaust/intake (or scavenging) is completed along with the compression of the mixture. The second stroke encompasses the combustion of the mixture, the expansion of the burnt mixture and, near bottom dead center, the beginning of the scavenging flows. Two-stroke engines often have a higher power-to-weight ratio than a four-stroke engine, since their power stroke occurs twice as often. Two-stroke engines can also have fewer moving parts, and thus be cheaper to manufacture and weigh less. In countries and regions with stringent emissions regulation, two-stroke engines have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-Stroke Engine
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a Thermodynamic power cycle, power cycle with two strokes of the piston, one up and one down, in one revolution of the crankshaft in contrast to a four-stroke engine which requires four strokes of the piston in two crankshaft revolutions to complete a power cycle. During the stroke from bottom dead center to top dead center, the end of the exhaust/intake (or Scavenging (automotive), scavenging) is completed along with the compression of the mixture. The second stroke encompasses the combustion of the mixture, the expansion of the burnt mixture and, near bottom dead center, the beginning of the scavenging flows. Two-stroke engines often have a higher power-to-weight ratio than a four-stroke engine, since their power stroke occurs twice as often. Two-stroke engines can also have fewer moving parts, and thus be cheaper to manufacture and weigh less. In countries and regions with stringe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compression Ignition
The diesel engine, named after the German engineer Rudolf Diesel, is an internal combustion engine in which ignition of diesel fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is called a compression-ignition engine (CI engine). This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine (gasoline engine) or a gas engine (using a gaseous fuel like natural gas or liquefied petroleum gas). Introduction Diesel engines work by compressing only air, or air combined with residual combustion gases from the exhaust (known as exhaust gas recirculation, "EGR"). Air is inducted into the chamber during the intake stroke, and compressed during the compression stroke. This increases air temperature inside the cylinder so that atomised diesel fuel injected into the combustion chamber ignites. The torque a diesel engine produces is controlled by manipulating the ai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crankcase
A crankcase is the housing in a reciprocating engine, piston engine that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block. Two-stroke engines typically use a crankcase-compression design, resulting in the fuel/air mixture passing through the crankcase before entering the Cylinder (engine), cylinder(s). This design of the engine does not include an oil sump in the crankcase. Four-stroke engines typically have an oil sump at the bottom of the crankcase and the majority of the engine's oil is held within the crankcase. The fuel/air mixture does not pass through the crankcase, though a small amount of exhaust gasses often enter as "blow-by" from the combustion chamber, particularly in engines with worn rings. The crankcase often forms the upper half of the main bearing journals (with the bearing caps forming the other half), although in some engines the crankcase completely surrounds the main bearing journals. An ''open-crank'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piston
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder (engine), cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering Porting (engine)#Two-stroke porting, ports in the cylinder. __TOC__ Piston engines Internal combustion engines An internal combustion piston engine, internal combustion engine is acted upon by the pressure of the expanding combustion gases in the combustion chamber space at the top of the cylinder. This force then acts dow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scavenging (automotive)
Scavenging is the process of replacing the exhaust gas in a cylinder of an internal combustion engine with the fresh air–fuel mixture (or fresh air, in the case of direct-injection engines) for the next cycle. If scavenging is incomplete, the remaining exhaust gases can cause improper combustion for the next cycle, leading to reduced power output. Scavenging is equally important for both two-stroke and four-stroke engine A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directi ...s. Most modern four-stroke engines use crossflow cylinder heads and valve timing overlap to scavenge the cylinders. Modern two-stroke engines use either Schnuerle scavenging (also known as "loop scavenging") or uniflow scavenging. The scavenge or scavenging port refers to that port through which clean air ent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Combustion Engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons (reciprocating engine, piston engine), turbine blades (gas turbine), a Wankel engine, rotor (Wankel engine), or a propulsive nozzle, nozzle (jet engine). This force moves the component over a distance. This process transforms chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to. The first commercially successful internal combustion engines were invented in the mid-19th century. The first modern internal combustion engine, the Otto engine, was designed in 1876 by the German engineer Nicolaus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chainsaws
A chainsaw (or chain saw) is a portable handheld power saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. Modern chainsaws are typically gasoline or electric and are used in activities such as tree felling, limbing, bucking, pruning, cutting firebreaks in wildland fire suppression, harvesting of firewood, for use in chainsaw art and chainsaw mills, for cutting concrete, and cutting ice. Precursors to modern chainsaws were first used in surgery, with patents for wood chainsaws beginning in the late 19th century. A chainsaw comprises an engine, a drive mechanism, a guide bar, a cutting chain, a tensioning mechanism, and safety features. Various safety practices and working techniques are used with chainsaws. History In surgery A "flexible saw", consisting of a fine serrated link chain held between two wooden handles, was pioneered in the late 18th century (–1785) by two Scottish doctors, John Aitken and James Jeffray, for symphysiot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chainsaw
A chainsaw (or chain saw) is a portable handheld power saw, power saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. Modern chainsaws are typically gasoline or electric and are used in activities such as tree felling, limbing, Log bucking, bucking, pruning, cutting firebreaks in wildland fire suppression, harvesting of Wood fuel#Firewood, firewood, for use in Chainsaw carving, chainsaw art and chainsaw mills, for cutting concrete, and cutting ice. Precursors to modern chainsaws were first used in surgery, with patents for wood chainsaws beginning in the late 19th century. A chainsaw comprises an engine, a drive mechanism, a guide bar, a cutting chain, a tensioning mechanism, and safety features. Various safety practices and working techniques are used with chainsaws. History In surgery A "flexible saw", consisting of a fine serrated link chain held between two wooden handles, was pioneered in the late 18th century (–1785) by two Scot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dugald Clerk
Sir Dugald Clerk (sometimes written as Dugald Clark) KBE, LLD FRS (1854, Glasgow – 1932, Ewhurst, Surrey) was a Scottish engineer who designed the world's first successful two-stroke engine in 1878 and patented it in England in 1881. He was a graduate of Anderson's University in Glasgow (now the University of Strathclyde), and Yorkshire College, Leeds (now the University of Leeds). He formed the intellectual property firm with George Croydon Marks, called Marks & Clerk. He was knighted on 24 August 1917. Life Dugald Clerk was born in Glasgow on 31 March 1854, the son of Donald Clerk a machinist and his wife, Martha Symington. He was privately tutored then apprenticed to the firm of Messrs H O Robinson & Co in Glasgow. From 1871 to 1876 he went to Anderson College in Glasgow studying engineering then to the Yorkshire College of Science in Leeds. In the First World War he was Director of Engineering Research for the Admiralty. He married Margaret Hanney in 1883. He died i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Four-stroke Engine
A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed: #Intake: Also known as induction or suction. This stroke of the piston begins at top dead center (T.D.C.) and ends at bottom dead center (B.D.C.). In this stroke the intake valve must be in the open position while the piston pulls an air-fuel mixture into the cylinder by producing a partial vacuum (negative pressure) in the cylinder through its downward motion. #Compression: This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke (below). Both the intake and exhaust valves are closed during this stage. #Combustion: Also known as power or ignition. This is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power-to-weight Ratio
Power-to-weight ratio (PWR, also called specific power, or power-to-mass 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 source. It is also used as a measurement of performance of a vehicle as a whole, with the engine's power output being divided by the weight (or mass) of the vehicle, to give a metric that is independent of the vehicle's size. Power-to-weight is often quoted by manufacturers at the peak value, but the actual value may vary in use and variations will affect performance. The inverse of power-to-weight, weight-to-power ratio (power loading) is a calculation commonly applied to aircraft, cars, and vehicles in general, to enable the comparison of one vehicle's performance to another. Power-to-weight ratio is equal to thrust per unit mass multiplied by the velocity of any vehicle. Power-to-weight ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motor Glider
A motor glider is a fixed-wing aircraft that can be flown with or without engine power. The FAI Gliding Commission Sporting Code definition is: a fixed-wing aerodyne equipped with a means of propulsion (MoP), capable of sustained soaring flight without thrust from the means of propulsion. History In 1935, an occasional or auxiliary motor that could be retracted was suggested by Sir John Carden. This was incorporated into the Carden-Baynes Auxiliary that first flew on 8 August of the same year. A later version of the Budig glider was powered. Categories Most motor gliders are equipped with a propeller, which may be fixed, feathered (e.g. AMS-Flight Carat), or retractable. However jet engine-powered motorgliders are now available from some manufacturers, some of which are intended for use only as "sustainer" engines, i.e. for sustaining gliding flight rather than as self-launching aircraft. Sustainer motor gliders Sustainer motor gliders must be launched like an unpowere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
