Open large image in new tab »
Pic. 32. Ignition system: 1. Cover of the sensor-distributor of ignition; 2. Terminal for wire from the ignition coil; 3. Central carbon electrode; 4. Side electrode with terminal; 5. Rotor with central and outer contacts and noise suppression resistor; 6. Protective screen; 7. The holder of the front roller bearing; 8. Sensor base plate; 9. Screen; 10. Driven plate of centrifugal governor; 11. Weight; 12. Drive plate: 13. Ignition distributor housing: 14. Oil seal; 15. Roller sensor-distributor ignition; 16. Coupling; 17. Bushing of the rear end of the roller; 18. Vacuum regulator housing; 19. Union for vacuum supply; 20. Vacuum regulator diaphragm; 21. Vacuum regulator rod. 22. Proximity sensor; 23. Connector block: 24. Sensor support plate bearing; 25. Sleeve of the front end of the roller; 26. Felt ring; 27. Candle body; 28. Insulator; 29. Contact sleeve; 30. Contact rod; 31. O-ring; 32. Central electrode; 33. Heat sink washer; 34. Side electrode; 35. Ignition coil housing; 36. Terminal "TO" output of the end of the primary winding; 37. Lid; 38. High voltage central terminal; 39. Terminal "B" output of the beginning of the primary and the end of the secondary windings; 40. Contact spring of the central terminal; 41. Insulating paper windings; 42 Secondary winding; 43. Primary winding; 44. External magnetic circuit. 45. Core (internal magnetic core); 46. Insulator; 47. Sensor-distributor ignition; 48. Spark plugs; 49. Switch; 50. Ignition coil; 51. Mounting block; 52. Ignition relay; 53. Ignition switch; 54. Permanent magnet; 55. Semiconductor plate with an integrated circuit; I. Characteristics of the vacuum ignition timing regulator: A - ignition timing, deg; Р - rarefaction hPa (mmHg.); II. Characteristics of the centrifugal ignition timing controller; A - ignition timing, deg; n - frequency of rotation of the roller of the sensor-distributor of ignition, min-1; III. Scheme of operation of the sensor: V - voltage pulses at the output of the sensor; C - current pulses in the primary winding of the ignition coil; tn - current accumulation time; IV. Scheme of operation of the centrifugal ignition timing regulator: A - ignition timing, degrees; V. Scheme of the ignition system.
Contactless ignition system used on VAZ-2108, VAZ-2109 cars. consists of the following components: ignition distributor, switch, spark plugs, ignition coil, ignition switch and high voltage wires.
Ignition distributor
Type 40 3706 is used on engines 2108 and 21083 or 40.3706-10 on engines 21081 and serves to issue low voltage control pulses to the switch and to distribute high voltage pulses to spark plugs. These distribution sensors are four-spark with vacuum and centrifugal ignition timing controllers and with a non-contact microelectronic control pulse sensor. They differ only in the characteristics of the vacuum and centrifugal ignition timing controllers.
The ignition distributor is mounted on the housing of the auxiliary units and is driven directly from the rear end of the camshaft through the clutch 16. The roller rotates in two ceramic-metal bushings 17 and 25. The bushing 17 is lubricated with oil from the engine lubrication system, and the bushing 25 is surrounded by a felt ring 26, impregnated with oil, which is sufficient for the entire service life. On the roller are the details of the centrifugal ignition timing controller: the leading plate 12 with weights 11 and the driven plate 10. The leading plate is fixed on the roller, and the driven one, together with the screen 9, is integral with the sleeve put on the roller. The sleeve can be rotated on the roller within a small range.
The non-contact sensor 22 is fixed on the plate 8 and operates on the basis of the Hall effect, which consists in the occurrence of a transverse electric field in a semiconductor plate with current when a magnetic field is applied to it. The sensor consists of a semiconductor plate with an integrated circuit 55 and a permanent magnet 54 with a magnetic circuit. There is a gap between the plate and the magnet, in which there is a steel screen 9 with four slots.
When the screen body passes through the sensor gap (see picture), then the magnetic lines of force close through the screen and do not act on the plate. Therefore, there is no potential difference in the plate. If there is a screen slot in the gap, then a magnetic field acts on the semiconductor plate and the potential difference is removed from it.
An integrated circuit built into the sensor converts the potential difference that occurs on the plate into voltage pulses of negative polarity. Thus, when the screen body is in the gap of the sensor, then there is a voltage U 4max 0 at its output, approximately 3 V less than the supply voltage. If a screen slot passes through the sensor gap, then the voltage U 4min 0 at the sensor output is close to zero (no more than 0.4 V).
Switch
The electronic switch 49 is used to interrupt the current in the primary circuit of the ignition coil according to the signals of the proximity sensor. Interchangeable switches of various brands can be used: 3620.3734, HIM-52, BAT10.2, RT1903 or PZE4020. To interrupt the current, a special powerful high-voltage transistor is used.
The switch circuit has a device for automatically regulating the period t 4n 0 of current accumulation I 41 0 in the ignition coil, depending on the crankshaft speed. The magnitude of the current pulses I 41 0 is 8-9 A. In addition, there is an automatic shutdown of the current through the ignition coil when the engine is off, but the ignition is on. After 2-5 seconds after the engine stops, the output transistor turns off, without creating a spark on the spark plugs.
Spark plugs are used domestic type A-17DV-10 or FE65R made in Slovenia, or the like. These candles have a built-in noise suppression resistor of 4-10 kOhm. The design of candles is traditional. The gap between the electrodes of the candle is 0.7-0.8 mm.
Ignition switch
The ignition switch is mounted on the steering shaft bracket and is used in conjunction with the ignition relay type 113.3747-10, which is mounted under the instrument panel. The switch has a lock against restarting the starter while the engine is running and an anti-theft device. The principle of operation of this device is that after removing the key in position III (Parking), the locking rod extends from the housing, enters the groove on the steering shaft and blocks it.
Ignition coil
Ignition coil type 27.3705 with an open magnetic circuit, sealed, oil-filled. It is designed to convert low voltage current (12 V) into high voltage current (20-25 kV) for breakdown of the air gap between the electrodes of the spark plugs. It is a transformer with two windings: primary 43 and secondary 42.
Operation of the ignition system
When the engine is running, the proximity sensor emits pulses. V voltage per plug "6" switch, and he converts them into pulses. From the current in the primary winding of the ignition coil. At the moment of interruption of the current, the magnetic field in the ignition coil is sharply compressed and, crossing the turns of the winding, induces an EMF in it of the order of 22-25 kV. The high voltage current goes to the central terminal 2 of the ignition distributor, then through the contacts of the rotor 5 to the side electrode 6 and then to the spark plug, creating a spark discharge between its electrodes.
To obtain maximum engine power, it is necessary to ignite the combustible mixture a little earlier than the piston reaches TDC, and each engine speed requires its own ignition timing. So, at 750-800 rpm, the initial (installation) the ignition timing is 1°±1°for the 2108 engines, 6°±1°for the 21081 and 4°±1°for the 21083. With increasing engine speed, the ignition timing must increase, and this task is performed by the centrifugal ignition timing controller.
With an increase in the rotational speed, the weights 11 diverge under the action of centrifugal forces and turn the plate 10 together with the screen 9 by angle A in the direction of the roller rotation. Now the screen slot passes through the sensor gap earlier by angle A, and it gives out a pulse earlier, i.e. ignition advance is increased.
The vacuum regulator changes the ignition timing depending on the load on the engine. When the load is big (carburetor throttles are fully open), the content of residual gases in the combustible mixture is low and it burns faster, so ignition must occur later. Conversely, at low load (throttle valves are covered) the amount of residual gases in the working mixture is increased and the working mixture burns more slowly, so ignition must occur earlier.
The diaphragm 20 of the vacuum regulator is affected by a vacuum transmitted from the zone above the throttle valve of the first chamber of the carburetor. With small openings of the damper, under the action of vacuum, the diaphragm 20 is pulled back and the rod 21 turns the base plate 8 of the sensor against the direction of rotation of the roller. The ignition advance is increased. As the throttle opens further (load increase) the vacuum decreases, and the spring presses the diaphragm to its original position. The base plate of the sensor is rotated in the direction of rotation of the roller, and the ignition advance is reduced.