外文翻譯----柴油機(jī)的工作原理(存儲(chǔ)版)
【正文】 n device is the spark plug, an insulated conductor set in the wall or top of each cylinder. At the inner end of the spark plug is a small gap between 本科 生畢業(yè) 設(shè)計(jì)（論文）外文翻譯 3 two wires. The highvoltage current arcs across this gap, yielding the spark that ignites the fuel mixture in the cylinder. Because of the heat of bustion, all engines must be equipped with some type of cooling system. Some aircraft and automobile engines, small stationary engines, and outboard motors for boats are cooled by air. In this system the outside surfaces of the cylinder are shaped in a series of radiating fins with a large area of metal to radiate heat from the cylinder. Other engines are watercooled and have their cylinders enclosed in an external water jacket. In automobiles, water is circulated through the jacket by means of a water pump and cooled by passing through the finned coils of a radiator. Some automobile engines are also aircooled, and in marine engines sea water is used for cooling. Unlike steam engines and turbines, internalbustion engines develop no torque when starting, and therefore provision must be made for turning the crankshaft so that the cycle of operation can begin. Automobile engines are normally started by means of an electric motor or starter that is geared to the crankshaft with a clutch that automatically disengages the motor after the engine has started. Small engines are sometimes started manually by turning the crankshaft with a crank or by pulling a rope wound several times around the flywheel. Methods of starting large engines include the inertia starter, which consists of a flywheel that is rotated by hand or by means of an electric motor until its kiic energy is sufficient to turn the crankshaft, and the explosive starter, which employs the explosion of a blank cartridge to drive a turbine wheel that is coupled to the engine. The inertia and explosive starters are chiefly used to start airplane engines. The ordinary Ottocycle engine is a fourstroke engine。本科 生畢業(yè) 設(shè)計(jì)（論文）外文翻譯 1 A diesel engine works 【 Abstract】 In diesel engine cylinder, the piston part of the cycle in the pressed gases, and in another part of the work cycle of the bustion gas mixture within the cylinder so the piston top surface expansion high pressure (about 116 ~ 120Kgf/cm2)under high temperature (about 569176。 that is, in a plete power cycle, its pistons make four strokes, two toward the head (closed head) of the cylinder and two away from the head. During the first stroke of the cycle, the piston moves away from the cylinder head while simultaneously the intake valve is opened. The motion of the piston during this stroke sucks a quantity of a fuel and air mixture into the bustion chamber. During the next stroke, the piston moves toward the cylinder head and presses the fuel mixture in the bustion chamber. At the moment when the piston reaches the end of this stroke and the volume of the bustion chamber is at a minimum, the fuel mixture is ignited by the spark plug and burns, expanding and exerting a pressure on the piston, which is then driven away from the cylinder head in the third stroke. During the final stroke, the exhaust valve is opened and the piston moves toward the cylinder head, driving the exhaust gases out of the bustion chamber and leaving the cylinder ready to repeat the cycle. The efficiency of a modern Ottocycle engine is limited by a number of factors, including losses by cooling and by friction. In general, the efficiency of such engines is 本科 生畢業(yè) 設(shè)計(jì)（論文）外文翻譯 4 determined by the pression ratio of the engine. The pression ratio (the ratio between the maximum and minimum volumes of the bustion chamber) is usually about 8 to 1 or 10 to 1 in
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