Open large image in new tab »
1. Core. 2. Insulator. 3. External magnetic circuit. 4. Primary winding. 5. Secondary winding. 6. A layer of corrugated cardboard. 7. Insulating paper windings. 8. Frame of the secondary winding. 9. External insulation of the primary winding. 10. Spring. 11. Cover. 12. Output terminal of the end of the primary winding. 13. High voltage terminal (output of the beginning of the secondary winding). 14. Contact screw. 15. Terminal «+B» output of the beginning of the primary winding and the end of the secondary. 16. Coil mounting bracket. 17. Corps. 18. Insulator rib. 19. Heat sink washer. 20. O-ring. 21. Corps. 22. Rod. 23. Insulator. 24. Contact nut. 25. Central electrode. 26. Side electrode. 27. Contact part. 28. Spring ring. 29. Lock washer. 30. Washer. 31. Block. 32. Spring. 33. Cylinder. 34. Corps. 35. Rotor. 36. Locking rod of the anti-theft device. 37. Textolite washer. 38. Spring. 39. Roller. 40. Cylinder lug 41. Rotor lug 35. 42. Groove for anti-theft drive bushing. 43. Rotor slip rings 35.
Spark plug
The spark plug is designed to ignite the combustible mixture in the engine cylinders by a spark discharge between the electrodes.
On cars «Zhiguli» since 1973, candles A-7.5 XC have been used. Previously, candles A-7.5 BS were used. They differ only in the material of the insulator. The letter A in the designation of the candle indicates that the thread of the screwed part is M14X1.25, and for these candles the thread is made according to the ISO standard with an accuracy class of 6e. The numbers 7.5 are the length of the thermal cone (skirts) insulator. The second letter in the designation indicates the material of the insulator: B - boron corundum, X - chilumin. The last letter C means that the candle is sealed along the central electrode with a conductive material.
The design of the candles is non-separable. The steel body 21 has a threaded portion 19 mm long and a hexagonal portion with a wrench of 20.8 mm. A side electrode 26 made of nickel-manganese wire is welded to the body. The insulator 23 is made of high quality ceramic material, which has very high mechanical and electrical strength at high temperatures. The outer surface of the insulator is glazed to improve insulating properties and reduce moisture deposition, thereby reducing the possibility of surface discharge when high voltage is applied to the candle. In the hole of the insulator there is a composite central electrode, consisting of the actual electrode 25, made of a heat-resistant chromium-nickel alloy, and a steel rod 22. On the upper part of the rod there is a thread onto which a contact nut 24 is screwed to connect the tip of the high voltage wire. The rod 22 is filled in the insulator with conductive glass sealant, which does not allow the breakthrough of gases through the insulator opening. The gap between the body of the candle and the insulator is sealed by rolling the body around the collar of the insulator, as well as by a copper washer 19, which also serves to remove heat from the insulator to the body, maintaining the temperature of the insulator skirt at a certain level
This temperature depends on the length of the skirt and on the thermal stress of the engine. The longer the skirt, the worse the heat dissipation from the skirt to the body, the «hot candle. For each engine model, a spark plug is selected individually, since the skirt of the insulator must be heated to a temperature of 500-600°C. If the temperature is below 500°C, i.e. the skirt is short and the candle «cold», then carbon deposits will be intensively deposited on the skirt of the insulator. If the temperature is above 600°C, then the carbon deposits will burn out, but the engine will pre-ignite the combustible mixture from a heated skirt, and not from a spark. This phenomenon is called glow ignition and is manifested by knocking in the engine and by the fact that after the ignition is turned off, the engine continues to work for some time.
Approximately the thermal properties of the candle are determined by the length of the insulator skirt, which is indicated in the marking of the candle.
From the leakage of gases through the threads of the candle body, an o-ring 20 made of soft iron is used, which is clamped between its body and the surface of the socket in the cylinder head.
Ignition coil
On cars «Zhiguli» install an ignition coil of type B-117A of domestic production or B-117 of NRB production. The characteristics of these coils are the same, and the differences are only in small structural elements. The coil is located in the engine compartment and is mounted on two bolts welded to the bottom of the left wheel mudguard.
The ignition coil is used to convert low voltage intermittent current (12 V) into high voltage current (11-20 kV) for breakdown of the air gap between the electrodes of the spark plug. The coil is a transformer «iron» core 1 and an annular outer magnetic circuit 3. The core is made of electrical steel plates 0.5 mm thick, and the outer magnetic circuit consists of a 0.3 mm thick electrical steel tape rolled into two layers. To reduce eddy currents, the tape has vertical slots.
The core 1 is in a cardboard frame 8, on which the secondary winding 5 is wound. The primary winding 4 is wound on top of the secondary winding. The winding layers are separated from each other by layers of insulating paper, and the first layer is separated from the rest by a layer of corrugated cardboard. The primary winding is insulated from the secondary with insulating paper and plastic tape, and from the magnetic core with 3 layers of insulating cardboard.
The windings, together with the magnetic circuit and the core, are placed in a seamless aluminum case 17 and filled with transformer oil. Filling with oil increases the reliability of the insulation and improves the cooling of the windings. The windings are installed in the housing on a bowl-shaped insulator 2 made of ceramic material - steatite.
From above, the coil body is closed with a plastic cover 11, the shoulder of which is rolled in the body and sealed with a gasket made of oil and petrol resistant rubber. The terminals of the windings are connected to the terminals filled in the cover. To terminal 15 marked «+B», the conclusions of the beginning of the primary and the end of the secondary winding are soldered, and to terminal 12 (unmarked) the terminal of the end of the primary winding is soldered. Output of the beginning of the secondary winding (high voltage output) connected to the core plates and, further, through the spring 10 and screw 14 with terminal 13, to which the high voltage wire is connected.
Ignition switch
On VAZ-2101 and VAZ-2102 vehicles, ignition switches of the VK-333 type without an anti-theft device or VK-347 ignition switches with an anti-theft device and with a contact part are installed. Only the VK-347 ignition switch is installed on the VAZ-2103 car, which is described here. The principle of operation and characteristics of the VK-333 switch are basically the same as those of the VK-347 switch.
The ignition switch is designed to turn on and off the ignition circuits, instruments, lights and other consumers of the car's electricity. It is mounted on a bracket on the left side of the steering column and secured with two screws.
The switch consists of a housing 34 with a lock and an anti-theft device and a contact part 27 fixed in the housing with a spring ring 28. steering shaft and block the shaft. In this case, the steering wheel must be turned left and right so that the groove of the shaft is against the locking rod of the lock The switch lock is designed so that the key can only be removed in the PARK and OFF positions.
The contact part has a steel roller 39, on which a plastic rotor 35 with slip rings 43 and a plastic cylinder 33 with projections are put on. In the head of the roller there is a groove 42, which includes the protrusion of the drive sleeve of the anti-theft device. One side of the slot is 2.5 mm wide and the other side is 2 mm wide. Therefore, the contact part 27 can only be installed in the housing 34 in one particular position. Spring 32 serves to return roller 39 from the STARTER position to the IGNITION position after the key is released.
Block 31 has brass rack-plugs with contacts. On stand-plugs «30» and «30/1» fixed bronze plates with contacts. The plates are pressed against the surface of the cylinder 33 by leaf springs. In the IGNITION and STARTER positions, the protrusions of cylinder 33 press these plates and contacts «30—50» and «15—30/1» close. In addition, racks «30», «INT» and «16» have contacts that are closed by slip rings 43 of the rotor 35. The rotor is pressed against these contacts by the spring 38.
Voltage from the battery and generator is supplied to the contacts «30» and «30/1». Contact «16» switch is not used yet. The diagram shows which contacts close at different key positions.
Distributor
Open large image in new tab »
1. Shaft of the distributor of ignition. 2. Oil flinger. 3. Capacitor. 4. Wire from the ignition coil to the distributor. 5. Spring clip of the lubrication channel of the oiler. 6. Oiler body. 7. Terminal screw. 8. Eccentric octane corrector. 9. The axis of the eccentric. 10. Eccentric spring. 11. Breaker cam. 12. Grease wick (field) cam. 13. Base plate of the ignition timing regulator. 14. Weight of the ignition timing regulator. 15. Weight stop. 16. Rotor fastening screw. 17. Ignition distributor rotor. 18. Ground electrode with terminal for wire to spark plug. 19. Ignition distributor cover. 20. Central terminal for the wire from the ignition coil. 21. Central carbon electrode with a spring. 22. Rack of fastening of a spring with a limiter. 23. Leading plate of the ignition timing regulator. 24. The axis of the weight. 25. The axis of the breaker lever. 26. Insulating sleeve. 27. Lever spring. 28. Textolite block of the lever. 29. Breaker lever. 30. Movable contact breaker. I. Interrupter connecting conductor. 12. Fixed contact of the breaker. 13. Stand screw. 14. Spring for fastening the cover. 15. Fixed breaker plate. 16. Rack with breaker contacts. 17. Movable breaker plate. 18. Base plate. 19. Ceramic-metal porous roller sleeve. 10. Ignition distributor housing. 11. Oil flinger washer. 42. Spiral hairpin. 43. Center contact of the rotor 44. Resistor. 45. External contact of the rotor. 46. The thrust axis of the octane corrector. 47. Thrust octane corrector. 48. Grease wick (felt) roller bushings. 49. Rubber boot. 50. Wire tip. 51. Conductive winding. 52. Inner shell. 53. Linen fiber core. 54. Outer insulating sheath. 55. Generator. 56. Ignition switch. 57. Ignition coil. 58. Ignition distributor breaker. 59. Ignition distributor. 60. Battery. 61. Spark plugs.
The ignition distributor serves to interrupt the current in the low voltage circuit of the ignition coil and distribute the high voltage pulses to the spark plugs.
On cars «Zhiguli» a four-spark, unshielded ignition distributor type R-125 is used (R-125B for VAZ-2103) with a centrifugal ignition timing controller and an octane corrector.
The R-125 and R-125B ignition distributors differ in the characteristics of the ignition timing regulator and the length of the lower part of the shaft 1 protruding from the housing 40: for the R-125 distributor, the size from the housing support flange to the end of the shaft is 127.5 mm, and for the R- distributor 125B - 136.3 mm.
The housing 40 of the distributor is cast from an aluminum alloy and has a porous ceramic-metal bushing 39 in which the roller 1 rotates. Grease is supplied to the bushing through a felt wick (felt) 47 from oiler 6.
The main parts of the ignition distributor: chopper, centrifugal ignition timing controller and the distributor itself.
The breaker consists of a cam 11 with four projections and a rack 36 with contacts that the cam opens during rotation. The cam is lubricated with felt felt 12 impregnated with oil. An axle 25 is riveted to the post 36, on which a lever 29 with contact 30 is installed on a textolite sleeve 26, pressed by a leaf spring 27 to contact 32 of the post. The current to the lever contact is supplied from screw 7 through conductor 31 and spring 27.
Rack 36 is fixed with two screws 33 on the movable plate 37 of the interrupter. The lower end of the axis 25 of the lever enters the hole of the movable plate. Therefore, when adjusting the gap between the contacts, the rack can be rotated around this axis after loosening the screws 33.
The movable plate 37 of the interrupter is soldered to the sleeve through which the distributor roller passes. A plastic support plate 38 and a fixed breaker plate 35 are put on this sleeve. These plates are compressed by a spring washer and secured to the bushing with a retaining ring. The movable plate 37 of the interrupter with the rack 36 can be rotated by the octane corrector rod 47, which allows you to manually adjust the ignition timing within a small range.
The cam 11 is not driven directly from. distributor roller, and through the weights and can be rotated by them by 15°relative to the distributor roller.
A base plate 13 of the ignition timing controller is soldered to the upper end of the cam bushing. Axes 24 are riveted to the plate, on which metal-ceramic weights rotate. Racks 22 of springs are pressed into plate 23. The lower parts of the axles are limiters. They enter the oval grooves of the plate 13 and do not allow it to rotate relative to the distributor shaft by more than 15°.
The distributor consists of a rotor 17 and electrodes installed in a plastic cover 19. The pastemass rotor 17 is fixed with two screws 16 on the plate 13 of the ignition timing regulator. The rotor is fixed in a certain position, which is ensured by square and round holes in the plate 13, which include the same section of the protrusions of the rotor. The central 43 and outer 45 rotor contacts are riveted on the rotor, between which there is a 5000-6000 Ohm resistor 44 in a special recess, designed to suppress radio interference.
A spring-loaded carbon electrode 21 rests against the central contact of the rotor, which transmits high voltage pulses from the ignition coil to the rotor. When the rotor rotates, these pulses are transmitted from the outer contact 45 to the side electrodes 18, filled in the cover, and, further, to the spark plugs.
A capacitor 3 with a capacity of 0.20-0.25 microfarads is fixed on the ignition distributor housing.
High voltage wires
High voltage wires are used to transmit high voltage current pulses from the ignition coil to the distributor and from the distributor to the spark plugs. To reduce radio and television interference, the wires have a resistance distributed along the length of 2000 Ohm / m. The core 53 of the wire, which is a cord of linen yarn, is enclosed in a sheath 52 made of plastic with a maximum addition of ferrite. A wire ∅ 0.11 mm from an alloy of nickel and iron is wound over this sheath.
Operation of the ignition system
The ignition system has a primary circuit (low voltage) and secondary (high voltage). The current in the primary circuit closes along the path: «plus» battery - contacts «30/1», «15» ignition switch - clip «+B»,
primary winding of the coil - breaker 58 - ground - «minus» battery. If the alternator voltage is greater than the battery voltage, current flows from the clamp «30» generator and closes through the ground to its rectifier. The rest of the current path is the same as described above.
The current flowing through the primary winding of the ignition coil creates a magnetic force field around the turns. When the breaker contacts are opened, the current in the primary circuit disappears, the magnetic force field is sharply reduced and, crossing the turns of the primary and secondary windings, induces an EMF in them proportional to the number of turns. In the secondary winding, the EMF reaches 12000-24000 V, and in the primary - 200-300 V. The faster the magnetic lines of force cross the turns of the windings (i.e. faster disappearance of the magnetic field), the greater the EMF induced in them.
The EMF induced in the primary winding of the ignition coil is called self-induction EMF. It seeks to maintain the vanishing current and therefore slow down the contraction of the magnetic field. In addition, it causes sparking between the open contacts of the breaker. To prevent these phenomena, there is a capacitor 3 in the ignition distributor. At the initial moment of contact opening, the self-induction current charges the capacitor, which reduces the current flow between the breaker contacts and sparking between them. The capacitor is then discharged through the primary winding of the ignition coil, with the discharge current being directed against the self-inductive current, whereby the current in the primary circuit disappears faster and therefore the magnetic field is reduced faster.
The high voltage current induced in the secondary winding of the ignition coil is closed in the following way: the secondary winding of the ignition coil - high voltage wire - the central terminal of the cover, the central terminal 43, the resistor 44, the outer contact 45 of the rotor, the side electrode of the distributor cover - the spark plug - ground. Then, in parallel circuits, the current passes through the battery, through the generator, through all the included consumers to the contacts «30/1» and «15» ignition switch, and then on the clamp «+B» to the secondary winding of the ignition coil.
A high voltage applied to the center electrode of the spark plug pierces the air gap between the electrodes and a spark jumps between them, igniting the working mixture in the engine cylinder.
To obtain maximum power and efficiency of the engine, it is necessary to ignite the working mixture a little earlier than the arrival of the piston in the top dead center, so that combustion ends when the crankshaft crank turns 10-15°after the top dead center, i.e. spark discharge should be created with the necessary advance.
Each engine speed requires its own ignition timing. With a decrease in the speed of the crankshaft, the ignition timing should decrease, and with an increase in the speed of rotation, increase. This work is performed by a centrifugal ignition timing controller. With an increase in the frequency of rotation of the distributor roller, the weights 14 rotate relative to the axes under the action of centrifugal force, the protrusions of the weights abut against the drive plate 23 and, overcoming the tension of the springs, rotate the support plate 13 together with the cam 11 of the interrupter in the direction of rotation of the distributor shaft at an angle a. The cam protrusions open the breaker contacts earlier and the ignition advance increases. With a decrease in the rotational speed of the roller, the centrifugal forces acting on the weights decrease and the springs turn the base plate 13 with the cam 11 against the direction of rotation of the roller, i.e., the ignition timing decreases.