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单词 ignition system
释义

ignition system


ignition system

See: firing system.
Thesaurus
Noun1.ignition system - the mechanism that ignites the fuel in an internal-combustion engineignition system - the mechanism that ignites the fuel in an internal-combustion engineignitionelectrical distributor, distributer, distributor - electrical device that distributes voltage to the spark plugs of a gasoline engine in the order of the firing sequenceelectrical system - equipment in a motor vehicle that provides electricity to start the engine and ignite the fuel and operate the lights and windshield wiper and heater and air conditioner and radioignition coil - an induction coil that converts current from a battery into the high-voltage current required by spark plugsignition switch - switch that operates a solenoid that closes a circuit to operate the startermagneto, magnetoelectric machine - a small dynamo with a secondary winding that produces a high voltage enabling a spark to jump between the poles of a spark plug in a gasoline enginemechanism - device consisting of a piece of machinery; has moving parts that perform some functionspark coil - an induction coil used to create sparksspark gap - a component of an ignition system; consists of two shaped electrodes and the space between themspark plug, sparking plug, plug - electrical device that fits into the cylinder head of an internal-combustion engine and ignites the gas by means of an electric spark

ignition system


ignition system

[ig′nish·ən ‚sis·təm] (mechanical engineering) The system in an internal combustion engine that initiates the chemical reaction between fuel and air in the cylinder charge by producing a spark.

Ignition system

The system in an internal combustion engine that initiates the chemical reaction between fuel and air in the cylinder charge by producing a spark. An ignition system for a multicylinder internal combustion engine has three basic functions: (1) to provide a sufficiently energetic spark to initiate the burning of the fuel-air mixture within each cylinder; (2) to control spark timing for optimum efficiency so that cylinder pressure reaches its maximum value shortly after the piston reaches the top of its compression stroke; and (3) to select the correct cylinder fired.

In an inductive ignition system, there are three possible types of control-vacuum-mechanical, electronic spark, or full electronic engine. Prior to spark discharge, electrical energy is stored inductively in the coil primary. The current to the coil primary winding is turned on and off by the ignition module in response to the spark-timing trigger signal. The current-off time marks the beginning of the sparking event. An accurate spark-timing schedule is a complex function of many engine variables, such as fuel-air composition, engine revolutions per minute (rpm), temperature, cylinder pressure, exhaust gas recirculation rate, knock tendency, and engine design.

The ignition coil stores electrical energy during the dwell (current-on) period and acts as a transformer at the end of dwell by converting the low-voltage-high-current energy stored in the primary to high-voltage-low-current energy in the secondary. The distributor selects the fired spark plug by positioning the rotor opposite the terminal connected to one spark plug. The plug selected depends on the cylinder firing order, which in turn depends on the engine design. The distributor is driven at one-half engine speed from the camshaft. See Spark plug

When high voltage (10–30 kV) is created in the coil secondary, a spark jumps from the rotor to a distributor cap terminal, establishing a conducting path from the ignition coil high-voltage terminal along a high-voltage wire to the spark plug. Each cylinder usually has one spark plug. (High-efficiency engines may have two spark plugs per cylinder and two complete ignition systems.) The plug electrodes project as far into the cylinder as possible. After high voltage is applied to the plug, an electrical discharge is generated between its two electrodes. The energy and temperature of this discharge must be sufficient to reliably ignite the fuel-air mixture under all encountered conditions of composition, temperature, and pressure.

Among the several other types of ignition systems for internal combustion engines are capacitive discharge, multiple-firing capacitive discharge, continuous sustaining, magneto, and distributorless ignitions. The input energy for capacitive discharge systems is stored on a capacitor at several hundred volts (generated by a dc-dc converter). A semiconductor switch (thyristor) controls the discharge of the capacitor into the primary winding. In a multiple-firing capacitive discharge ignition, the ignition module repetitively fires a capacitive discharge ignition during one spark event, increasing both the energy and effective time duration of the spark. In a continuous sustaining ignition, supplemental electrical power is added to the spark after it is established, resulting in electronically controlled extended duration rather than uncontrolled duration as for conventional ignitions. In a magneto ignition, electric current and energy are generated in the primary by relative rotational motion between a magnet and a coil (electromagnetic induction). High voltage is generated in the secondary when a set of contacts in the primary circuit is mechanically opened. Magnetos require no external source of electrical power.

The distributorless ignition system eliminates the need for mechanical distribution of spark energy by using a single coil for one, two, or four cylinders. For the two-cylinder-single-coil system, a double-ended ignition coil simultaneously fires a cylinder in a compression stroke together with a second in an exhaust stroke. The exhaust stroke cylinder accepts the waste spark to complete the electrical circuit through the engine block. A design variation uses alternating polarity high voltage from a special type of double-ended coil and four high-voltage rectifiers to fire four plugs. The rectifiers steer the voltage to the correct pair of plugs.

In diesel or compression ignition engines, sparkless ignition occurs almost immediately after fuel injection into the cylinder due to high in-cylinder air temperatures. High temperatures result from the high compression ratio of diesel engines. Mechanical or electronic injection timing systems determine ignition timing. See Combustion chamber, Diesel engine, Internal combustion engine

ignition system


Related to ignition system: ignition coil
  • noun

Synonyms for ignition system

noun the mechanism that ignites the fuel in an internal-combustion engine

Synonyms

  • ignition

Related Words

  • electrical distributor
  • distributer
  • distributor
  • electrical system
  • ignition coil
  • ignition switch
  • magneto
  • magnetoelectric machine
  • mechanism
  • spark coil
  • spark gap
  • spark plug
  • sparking plug
  • plug
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更新时间:2024/12/23 22:09:02