專業(yè)英語準論文The engine Ignition-system ).doc

成 績評閱人The engine Ignition-system Service and Maintenance學院： 學期：2010-2011第二學期 課程： 專 業(yè) 英 語 專業(yè)： 車輛工程 班級： 學號： 姓名： The engine Ignition-system Service and MaintenanceThe gasoline engine in the compression on the check point, close to the mixture is the spark plug ignites, thus burning to do work, for this, the foreign gasoline engine in the combustion chamber are equipped with the spark plug. The spark plug has a central electrode and a side electrode, two of the insulation between electrodes is. When two electrodes in the spark plugs and dc voltage is the voltage between and increase to a certain value, the spark plug the gap between two electrodes will be breakdown and produce electric spark, can spark plug in the generation between two electrodes to minimum voltage electric spark of called breakdown voltage; Can spark plug the generation between two electrodes in all the equipment of electric spark called engine ignition system.Composition: The ignition system mainly by the power supply, the ignition switch, ignition coil, cut-out relay, with electrical appliances, capacitor, spark plug, high voltage wires, additional resistance etc Traditional ignition system by batteries, generators, ignition coil, cut-out relay, spark plug etc. Common type and traditional ignition system is similar to use electronic components to replace break electrical appliances. Electronic ignition type are all full electronic ignition system, completely cancelled a mechanical device, electronic ignition control system by time, including batteries, generators, ignition coil, spark plugs and electronic control system, etc.Function: The automotive ignition system has two basic functions: it must control the spark and timing of the spark plug firing to match varying engine requirements, and it must increase battery voltage to a point where it will overcome the resistance offered by the spark plug gap and fire the plug.Principle of work: The power supply is the battery, the voltage for 12 V or 24 V, ignition coil and broken by electrical produces high pressure common 10000 V above. The primary loop and times extremely points circuit. The ignition coil is actually a transformer, mainly by the primary winding, a winding and core of time. Broken appliances are a CAM of the manipulation of the switch. Broken appliances CAM driven by the engine with gas, and with the same speed rotation, namely the crankshaft gear every turn two laps, the camshaft turn around, in order to guarantee the crankshaft turning two laps in turn each cylinder ignition once, broken appliances CAM convex edges generally equal to the number of the number of cylinders, broken engine electrical contacts with the primary windings of ignition coil series, used to cut off or connect primary winding circuit.Contacts closed primary circuit, electricity, from the current battery positive ignition switch, ignition coil of the primary winding, broken appliances contacts, grounding flows back to the battery anode, for low voltage circuit.Contacts disconnect, when a current in the primary winding, its a magnetic field around, and because of the role of the iron core is reinforced. When broken appliances CAM top open contacts, primary circuit was cut off, primary circuit quickly drop to zero, the iron core magnetic flux then quickly to disappear, so the attenuation circle number, The Times very fine wires in the high winding inductive voltage, make the spark plug gap is between the poles of breakdown, produced sparks.The current decline in the primary windings of the larger in iron core, the speed of the flux change is bigger, time very winding of the induced voltage is also higher.The primary circuit for low voltage circuit, time for high voltage circuit extremely circuit.The broken electrical contacts in the moment, a separate times in the circuit is right with side there points on the electrode, times from a circuit ignition coils of times a winding, the high-pressure electric wire, match, spark plug, storage battery flows back to the electrode extremely winding time.Common fault and maintenance method: The carburetor, no high pressure sparks poor supply, spark plug or because of the oil leakage, the mixture is too strong flooded a spark plug, blunt cylinder bed of the air pressure caused by low or no, ignition timing, the temperature is too low to high pressure, high pressure pump engages the insufficient, nozzle spray bad. These are all cause engine unable to start or start difficult reason.The camshaft, sensor, good or bad, clearance, crankshaft whether computers, computer or normal power supply. The ignition system, some car insurance should check the pump and electrical appliances, etc.Fault classification.The ignition of fault in the ignition department according to its position can be divided into two kinds of situations: low voltage circuit faults and high voltage circuit fault.(1) Low voltage circuit common failure:Save battery power is insufficient; Line bad or disorder; Batteries take iron bad; Distributor or hall sensor damage; The ignition switch damage or wiring bad; Transistor ignition control unit of damage or wiring is poor. Low voltage circuit fault diagnosis method is used mostly ammeter or the voltmeter to exclude line examination by fault point.(2) High voltage circuit common fault:The high tension line fall off or leakage; Distributor cover rupture breakdown; Distributor points there ablation rupture breakdown; The spark plug electrode is too small or large clearance; Spark plug too much carbon deposition; The spark plug insulators damage; The ignition coil damage or wiring fall off.High voltage circuit fault mostly using high pressure to try the dominated, the high tension line or a cylinder distributor center high tension line pulling out, will thrum placed distance 3 and 6 mm in cylinder, starting the engine try fire, sparks and spark strong, explain the ignition is working properly.2. The ignition doesnt work. (1) Fault phenomena: open the ignition switches, starting the engine, engine no response; High pressure try fire, the high tension line no spark.(2) Failure analysis and diagnosis3. The ignition time premature(1) Fault phenomena: the idle smooth, easy operation not removes; Acceleration, the engine is serious deflagration of sound.(2) Failure analysis: the fault is mainly ignition timing adjusts misalignment or ignition Angle caused by using assembly.(3) Elimination method: even good ignition tester, adjust ignition timing to the rating.4. The ignition too late(1) Fault phenomena: muffler heavy, the anxious accelerate sound carburetor tempering; engine cooling fluid temperature is higher, automobile driving weak.(2) Failure analysis and diagnosis: ignition Angle is not correct.(3) Elimination method: adjust ignition Angle specified rating.Failure is shown as: the spark plug micro activity, grease and overheat wait for a phenomenonAt the end of an insulator spark plug, electrode and spark plug shell often covered with a thick layer of black, gray powder is soft fouling.The spark plug pollution: fault phenomena: an insulator ends, electrode and spark plug covering a layer of oil shell.The spark plug overheating: center electrode, the top loose, melting insulators soft, most of the insulators tan-white hard skin.6. The engine temper and blowingIf both the tempering and launched a sound, and while is very serious, while more of the high tension line of points cylinder into wrong and cause. If the phenomenon is not serious, but it occurred sporadically, there seems to rule, while more of the distributor with crack, make of cylinder darting caused by fire. Advanced ignition Angle deviating from the right place too much, also can cause the tempering or while exhaust.7. The engine knock and overheatingThe engine in the big load medium speed most prone to knock. In the use of fuel right, grades knock phenomena is because most advanced ignition Angle caused by excessive.In the detonation cases, launched a chance to warm up quickly. On the other hand, ignition timing too backward, ignition too late, the engine temperature will also is on the high side. Do not appear in the detonation, high water temperature is not caused most of the ignition, but with weakness, speed up the engine if not sensitive, it should check the ignition timing is too small.A variety of testing equipment can be used to test the various components of the ignition system.Ignition-coil tester. Two type of ignition-coil tester are in general use, the spark-gap type and the high-frequency type. The latter type is preferred. Condenser tester. A good condenser tester should be able to test the condenser for grounds or shorts and to measure the insulation resistance, series resistance, and capacity. These conditions all affect the performance of the ignition.Distributor tester. Distributor testers are variable-speed devices that drive the distributor at various speeds so that the operation of the centrifugal advance can be checked. They also may include a cam-angle meter to measure dwell, or cam angle. In addition, they usually have a vacuum device to test the operation of vacuum-advance mechanisms.Ignition timing devices. The contact points must be timed to close and open in proper relation to the piston positions in the cylinder.Any check of the ignition system should start at the battery and cables and should take in the coil, distributor, condenser, low-and high-tension wirin