时间：2011-03-11 23:18来源：蓝天飞行翻译 作者：航空 点击：次
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The secondary winding consists of many hundreds of turns of very fine copper wire wound on the outside of the primary winding. One end of the secondary winding connects to the primary, and the other end goes to the rotor of the distributor, a high-voltage selector switch that directs the high voltage to the proper spark plug. When the breaker points open, primary current stops flowing, and its magnetic field instantly collapses. As it collapses, the lines of flux cut across the turns of wire in the secondary winding and induce a high voltage in it. This high voltage produces the spark in the spark plug. spark-ignition engine (reciprocating engine). A form of reciprocating engine in which the fuel-air mixture inside the cylinder is ignited by an electric spark. The spark is timed to occur when the piston is in the correct position on the compression stroke. spark plug (reciprocating engine ignition system component). A device in the ignition system of a reciprocating engine that produces the spark which ignites the fuel-air mixture inside the cylinder. A spark plug has a steel shell and an insulated center electrode. Accurately spaced gaps are formed between the ground electrodes on the shell and the insulated center electrode. The high-voltage lead from the ignition distributor is connected to the insulated terminal of the spark plug and, at the correct time, a pulse of high-voltage electrical energy is sent to the spark plug. As this electrical energy passes to ground, it produces an intense spark between the two electrodes. spark plug bushing (aircraft reciprocating engine component). A threaded bronze or steel bushing screwed and shrunk into an opening in the cast aluminum cylinder head of an aircraft engine. The spark plugs screw into the bushings which protect the soft aluminum from damage when the spark plugs are changed. spark plug resistor. A resistor installed in a shielded spark plug between the ignition lead terminal and the center electrode. The capacitance in the shielded ignition lead stores enough energy to keep the spark flowing across the gap long enough to erode the electrodes. The resistor decreases the duration of the spark and thus minimizes electron erosion. spark suppressor. A device placed across a set of electrical contacts to suppress the spark that forms when the contacts open. Spark suppressors normally consist of a capacitor and resistor and sometimes a diode across the contacts. spark test (metal identification method). A quick test to identify types of ferrous metal. A sample of the metal is pressed against a grinding wheel, and the pattern of sparks thrown off indicates of the type of metal. When wrought iron which contains no carbon is held against the wheel, the sparks stream out in a straight line. The lines of sparks grow wider and brighter as they stream out behind the wheel. Mild steel, with its low carbon content, has a spark pattern similar to that of wrought iron, except some of the sparks have tiny forks on them. The spark pattern for tool steel with its high carbon content is similar to that for mild steel, except there are more forks in the stream, and the forked sparks form close to the wheel. Cast iron produces a large number of sparks close to the wheel, but they die out quickly. The spark pattern for cast iron is very short. |
