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Pic. 30. Generator: 1. Cover of the generator from the side of slip rings; 2. Bolt for fastening the rectifier unit; 3. Contact rings; 4. Ball bearing of the rotor shaft on the slip ring side; 5. Capacitor 2.2uF±20% to suppress radio interference; 6. Rotor shaft; 7. Wire common output of additional diodes; 8. Clamp "30" generator for connecting consumers; 9. Plug "61" generator (common output of additional diodes); 10. Output wire "B" voltage regulator; 11. Brush connected to the outlet "IN" voltage regulator; 12. Voltage regulator; 13. Brush connected to the terminal "W" voltage regulator; 14. Stud for attaching the generator to the tensioner; 15. Cover of the generator from the side of slip rings; 16. Fan impeller with generator drive pulley; 17. Pole tip of the rotor; 18. Bearing mounting washers; 19. Distance ring; 20. Ball bearing drive side rotor shaft; 21. Steel sleeve; 22. Rotor winding (excitation winding); 23. Stator core; 24. Stator winding; 25. Rectifier block; 26. Coupling bolt of the generator; 27. Buffer sleeve; 28. Sleeve; 29. Clamping sleeve; 30. Negative diode; 31. Insulating plate; 32. Phase output of the stator winding; 33. Positive diode; 34. Additional diode; 35. Positive diode holder; 36. Insulating sleeves; 37. Negative diode holder; 38. Generator; 39. Battery discharge indicator lamp; 40. Voltmeter; 41. Mounting block; 42. Additional resistors of 100 ohms, 2 W; 43. Ignition switch; 44. Battery.
On cars VAZ-2108, VAZ-2109, a three-phase alternator of type 37.3701 is used with a built-in rectifier unit and a microelectronic voltage regulator. It serves to supply consumers with electric current and to charge the battery. Maximum generator output current (at 13 V and 5000 rpm) is 55 A, and the limits of the regulated voltage are 14.1±0.5 V.
The main parts of the generator: a rotor, a stator, a cover 1 with a rectifier unit 25, a cover 15 with a bearing 20, a pulley with a fan 16 and a brush holder with a voltage regulator 12. The covers and the stator are pulled together by four tie bolts 26.
The generator rotor is a rotating electromagnet. Steel beak-shaped pole pieces 17 and bushing 21, pressed onto the rotor shaft 6, form the core of the electromagnet. Between the pole pieces in a plastic frame is the winding 22 of the rotor, called the excitation winding. The current is supplied to the winding through copper contact rings 3, to which the winding leads are soldered.
The rotor shaft rotates in two ball bearings 4 and 20 installed in covers 1 and 15. Closed type bearings. The lubricant incorporated in them during manufacture is sufficient for the entire service life of the generator. The rear bearing 4 is pressed onto the rotor shaft, and its outer race is pressed by a rubber ring placed in the cover groove. The front bearing 20 is pressed into the cover 15 and, for reliability, is clamped between two steel washers 18, tightened with four screws. The ends of the screws are punched. The inner race of this bearing, together with the distance ring 19, is clamped by a pulley fastening nut between the pulley hub and the shaft step.
The generator stator consists of a core 23 with a winding 24. The core is made of plates of electrical steel, connected in four places by electric welding. In the grooves of the core, a three-phase stator winding is laid, the ends of which are connected in a star without a zero point output.
The rectifier that converts the alternating current of the generator to direct current is made in the form of a rectifier unit 25. It consists of two aluminum plates with six diodes of the VA-20 type pressed into them - semiconductor devices that pass current in only one direction. To simplify the design of the rectifier, diodes of different polarity are used - "positive" And "negative". For positive diodes on the case, a "plus" rectified voltage, and for negative - "minus". Positive diodes are pressed into plate 35 of the rectifier unit, and negative diodes into plate 37.
The rectifier unit is attached to the cover 1 with three bolts 2, insulated together with the positive diode plate 35 from the cover with plastic bushings. The nuts of the bolts 2 simultaneously clamp the leads of the diodes and the stator winding. Clamp connected to plate 35 "30" (8) generator, which is the output "plus" rectifier. Conclusion "minus" is the mass of the generator.
Three additional diodes 34 are also installed on the plate 35 of the rectifier unit. The voltage removed from these diodes is used to power the excitation winding 22 and the generator health monitoring circuit using a battery discharge warning lamp 39.
The generator voltage is regulated by a microelectronic non-contact voltage regulator 12, fixed with a screw on the cover 1. This is a non-separable and unregulated unit and it completely lacks any electromagnetic relays with contacts. Closing or opening of the power supply circuit of the excitation winding of the generator occurs due to the opening or closing of a powerful output transistor in the regulator, depending on the magnitude of the control voltage at the output "B" regulator.
A plastic brush holder with two brushes 11 and 13 is inserted into the groove of the voltage regulator, through which the excitation winding of the generator is fed. Brush 11 is connected to the outlet "IN" voltage regulator, and brush 13 - with an output "W". This output is located on the inside of the regulator and is not marked on its body.
Generator operation
Contacts close when ignition is turned on "15/1" And "30/1" ignition switch, then contacts "30" And "87" ignition relay (not shown in the picture), and a current begins to flow through the excitation winding of the generator, closing along the path: "plus" battery - clamp "30" generator 38 - mounting block 41 - contacts "30" And "87" ignition relay - fuse "5" mounting block - additional resistors 42 and in a parallel circuit through a lamp 39 - output "61" generator - output "IN" voltage regulator 12 - excitation winding 22 - output "W", the output transistor of the voltage regulator - "weight".
The control lamp of the 39th battery discharge is on, signaling that the excitation winding is powered by the battery.
The current flowing through the excitation winding creates a magnetic flux around the rotor poles. After starting the engine, the generator rotor rotates, and under each stator tooth passes either the south or the north pole of the rotor. Therefore, the magnetic flux passing through the stator teeth varies in magnitude and direction. This variable magnetic flux crosses the turns of the stator winding and creates an electromotive force in it.
The alternating voltage and current induced in the stator winding are rectified by the rectifier unit and the already rectified direct current taken from the terminal is used to power consumers "30" generator. At the same time, a rectified voltage is removed from the common output of additional diodes 34 to power the excitation winding of the generator.
In a working serviceable generator, the voltage at the clamp "30" and on the common output of additional diodes (plug "61") are the same. Therefore, no current flows through the control lamp 39, and it does not light up. In this case, the excitation winding of the generator is powered by a rectifier with three additional diodes, and the battery is charged by the generator.
If the control lamp 39 is on, this indicates a malfunction of the generator, that it either does not give voltage at all, or it is lower than the battery voltage. In this case, the voltage at the plug "61" (generator voltage) below clamp voltage "30" (battery voltage). Therefore, a current flows in the circuit between them, passing through the control lamp, and it burns.
With an increase in the rotor speed, the generator voltage increases. When it begins to exceed the level of 13.6-14.6 V, the output transistor in the voltage regulator 12 is turned off, and the current through the field winding is interrupted. The generator voltage drops, the transistor in the regulator opens and again passes current through the excitation winding.
The higher the frequency of rotation of the generator rotor, the longer the time of the closed state of the transistor in the regulator, therefore, the more the generator voltage decreases. The described process of locking and unlocking the regulator occurs with high frequency. Therefore, voltage fluctuations at the output of the generator are imperceptible and can practically be considered constant. maintained at the level of 13.6-14.6 V.