Tiếng anh cơ khí ô tô phần 2
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Tiếng anh cơ khí ô tô phần 2
_____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inte Tiếng anh cơ khí ô tô phần 2ernal combustion engines. To start such an engine. it is necessary to spin the engine crankshaft with sufficient speed for good mixing of air and fuel and adequate compression and ignition of the combustible charge. The minimum speed with which the crankshaft of an engine should be rotated to ensure Tiếng anh cơ khí ô tô phần 2 reliable starting of the engine is referred to as the cranking speed. It depends on the en-gine type and starting conditions.The starting speed is 40Tiếng anh cơ khí ô tô phần 2
to 50 rpm for carburettor engines and 150 to 250 rpm for diesel engines. Cranking the engine with a lower speed makes it more difficult for the engin_____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inte Tiếng anh cơ khí ô tô phần 2 a result of which both the pressure and temperature of the charge at the end of the compression stroke are reduced.Much effort is required to crank the engine during starting, since it is necessary to overcome friction in the moving engine components and the resistance offered by the charge being c Tiếng anh cơ khí ô tô phần 2ompressed. This effort depends on the engine temperature, growing higher with decreasing temperature, because of the increasing viscosity of lubricatiTiếng anh cơ khí ô tô phần 2
ng oil.Diesels and gasoline engines are not self-starts. In order to start them, the engine crankshaft must be turned over by some outside means so as_____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inte Tiếng anh cơ khí ô tô phần 2_______________________ combustion engines may be started by the following methods: hand starting, ZEelectric starter motor, /gasoline engine, aecompressed-air motor, and ...compressed-air admission.Hand starting depends on the muscle power of the operator to turn the crank handle hooked to the engi Tiếng anh cơ khí ô tô phần 2ne crankshaft or to tug at the starting rope wound around the engine flywheel. In the early days of the automobile, it was necessary for the operatorTiếng anh cơ khí ô tô phần 2
to start the engine with a hand crank. In other words, the driver had to insert a crank into the front of the engine and turn it by hand until the eng_____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inte Tiếng anh cơ khí ô tô phần 2 not crank the engine. Moreover, without an electrical starting system, the early engines had design limitations in respect to displacement and compression ratio.Electric motor starting is the most common method used for starting automobile engines. In 1910, Charles F. Kettering began to work on a p Tiếng anh cơ khí ô tô phần 2ractical electrical automotive starter. The resulting system first appeared on the 1912 Cadillac; other manufacturers quickly adopted it for their ownTiếng anh cơ khí ô tô phần 2
passenger vehicles. This resulted in an increase in the popularity and widespread use of automobiles.With the development of the starting motor, the _____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inte Tiếng anh cơ khí ô tô phần 2 Also, a generator was needed to charge the battery in order to replace the electrical energy used by the starter.The starting system provides the power to turn the internal combustion engine over until it can operate under its own power. To perform this task, the starting motor receives electrical Tiếng anh cơ khí ô tô phần 2power___________________________215___________________________ from the battery, and it converts this energy into mechanical energy, which transmits tTiếng anh cơ khí ô tô phần 2
hrough the drive mechanism to the engine’s flywheel.The typical starting system has five components: battery, starting switch, battery cables, starter_____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inte Tiếng anh cơ khí ô tô phần 2tor can draw a large amount of current from the battery in order to turn the Ì engine over. The starter for a large V-s engine, for example, I may require as much as 300 amperes of starting current.< ÍThe starting system is convenient to operate and consider-ably eases the driver’s work, but require Tiếng anh cơ khí ô tô phần 2s skilled maintenance and has only a small store of energy, which limits the number of possible starting attempts. Many engines using an electric starTiếng anh cơ khí ô tô phần 2
ting system are also provided with means for hand starting in case the storage battery or the starter motor should fail.To facilitate the starting of _____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inte Tiếng anh cơ khí ô tô phần 2engines have their starting systems controlled remotely, from the driver’s cab. Where an auxiliary engine is used for starting a diesel engine the auxiliary engine cranks the main one through a reduction gear referred to as the starting device.Gasoline-engine starting is used to start diesel engines Tiếng anh cơ khí ô tô phần 2. A small gasoline engine is mounted on the diesel engine. The shaft of the gasoline engine carries a pinion which can be meshed with teeth on the dieTiếng anh cơ khí ô tô phần 2
sel engine fly-wheel. The operator starts the gasoline engine by hand; when it has warmed up, he engages the starting gears. The diesel engine then tu_____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inte Tiếng anh cơ khí ô tô phần 2licity and of being able to start the diesel engine in extremely cold weather. The warmjacket water from the gasoline engine can be used to preheat the main engine, and then the gasoline engine can turn it over as long as needed.Compressed-air motors. In order to eliminate the storage battery, compr Tiếng anh cơ khí ô tô phần 2essed-air motors are sometimes substituted for electric motors for starting small engines. The air motor has a rotor with vanes, enclosed in a casing,Tiếng anh cơ khí ô tô phần 2
and is powered by compressed air from a storage tank. Unless compressed air is available, a special compressor is needed to recharge the storage tank_____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inte Tiếng anh cơ khí ô tô phần 2ch driven and driving discs:H-ftyw‘hX8l ring (starte.) bear of diesel engine: 9-starter-bear: I O-automatic starterbear release mechanism: Ị Ị-starter-bear control lever.Compressedair admission. The starting method most commonly used on engines of moderate and large size IS the compressed-air admiss Tiếng anh cơ khí ô tô phần 2ion method. The energy needed to Start the engine is stored by compressing air into one or more tanks. The compressed air is admitted through an automTiếng anh cơ khí ô tô phần 2
atic starting valve in the engine cylinder head when the piston is at top center at the start of power stroke. The pressure of the air pushes the pist_____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inte Tiếng anh cơ khí ô tô phần 2pon the air supply is cut off.The opening of the starting valve is timed, directly or indirectly, by cams on the camshaft. Usual starting air pressures on modern engines range from 250 to 300 psi.ĨÌĨMỞỊspin V.quaycompression n.sự nénensure vt.bào đảm Tiếng anh cơ khí ô tô phần 2_____________________213____________________miT FOURTEENEngine Starting SystemEase of starting is one of the major performance characteristics of inteGọi ngay
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