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Tehnica mecanica

Tehnica mecanica


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Sistemul de Aprindere al motoarelor cu 'scanteie'


Sistemul de Aprindere al motoarelor cu 'scanteie'




Sistemul de Aprindere al motoarelor cu 'scanteie'

Motoarele in care amestecul exploziv din piston este aprins prin scanteie-electrica, sunt instalate  in masini, motorete, barci, avioane, jucarii etc si toate au nevoie de a bobine de inductie plus un control cat mai eficient (functie de benzina, turatie, incarcare, temperatura..) al unghiului de 'Avans'.

Intrucat nu vin cu nimic nou in domeniu, cititi ce scrie omul asta in engleza..

IGNITION SYSTEM TYPES

While many variations exist, there are three basic types of ignitions:

  1. Conventional
  2. Distributor (Electronic)
    • mechanical and vacuum timing advance, or
    • electronic spark timing
  3. Electronic (Distributorless)

 CONVENTIONAL IGNITION




Conventional Ignition

A conventional ignition system includes points and a condenser, and is often referred to as a 'breaker point' system. Conventional ignition components include:

  • distributor
  • cam
  • cap
  • breaker lever
  • rotor
  • rubbing block
  • ignition coil
  • coil wire
  • contact points
  • secondary wires
  • capacitor
  • spark plugs

Within the conventional distributor, there is a cam that is driven by the engine's camshaft to determine ignition timing. This rotating cam opens the points which triggers secondary high voltage from the coil. The arc that triggers the coil is controlled by a capacitor. A condenser is used as a capacitor to store excess voltage that would otherwise burn the contact points. The voltage is transferred to each of the spark plugs through a rotor in the distributor. Timing advance is based on engine vacuum through a diaphragm.

(ELECTRONIC) DISTRIBUTOR IGNITION


HEI Distributor Assembly

With an electronic Distributor Ignition (DI), spark delivery is controlled by the distributor but spark timing is controlled by the ECM through an ignition module. The distributor assembly consists of:

  • cap
  • pick-up coil
  • rotor
  • pole piece
  • shaft
  • module
  • pick-up coil shield

Within an electronic ignition distributor, ignition coil triggering is controlled and performed electronically with a pickup coil and module. The pickup coil generates a very low voltage signal that is used by the module to switch a transistor (an electronic switch with no moving parts). When the transistor switches, it turns off the current flow through the coil. This triggers the surge of secondary voltage from the coil.



In electronically-controlled timing advance systems, the ignition module controls ignition timing for start-up, but relies on the ECM for base timing during all other operating conditions.

With early non-computer units, actual spark timing is controlled by vacuum or mechanical advance. The remaining secondary components are similar to those found in a conventional ignition.


HEI Ignition (4-Terminal)

The most common form of DI found on GM vehicles is the High Energy Ignition (HEI) system. The advantages of HEI are:

  • ability to fire leaner mixtures with high voltages
  • extended spark plug life
  • fewer moving parts with reduced service
  • precise ECM timing control (if so equipped)
  • electronically-controlled coil primary current

 (DISTRIBUTORLESS) ELECTRONIC IGNITION

Electronic Ignition (EI) System (Typical)

The distributorless Electronic Ignition (EI) system does not use a distributor. Instead, the secondary ignition wires connect directly to the ignition coils (one coil for every two spark plugs). The ignition module is typically mounted to the coils. Secondary voltage is triggered based upon electronic logic using a crankshaft position sensor. Timing is controlled by the ECM.

A typical EI system includes:

  • ignition module
  • ignition coils
  • crankshaft sensor
  • camshaft sensor (some applications)
  • crankshaft wheel

Ce castigam ??

Voi mai introduce cateva strofe (cand voi avea timp..) pentru a 'convige' de necesitatea instalarii pe Dacii, Oltcit-uri si restul vechiturilor, a Delcoului cu senzori, fara distributor (fara capac delco insa trebuie 4 bobine..) si a computerului de bord care va controla aprinderea.






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