Automobile generator G-309 and G-309K

Generator

The main producer of energy, which goes to power all consumers of electrical energy and to charge the battery when the engine is running at medium and high speeds of the crankshaft, is the generator. According to the principle of operation and structure, there are direct and alternating current generators. On modern tractors used in agriculture, alternating current generators with a voltage of 12V and a power of up to 1500 W are mainly installed.

 

Direct current generators have long been one of the main sources of electrical energy on tractors. But with the increase in the power of electricity consumers, the size and mass of direct current generators increased so much that it became impossible to place them on engines, and the increase in the frequency of rotation of the crankshaft of the engine increased the operation of the collector and brushes. Therefore, instead of direct current generators, alternating current generators are installed on tractors. Among them are alternating current generators with excitation from permanent magnets and with electromagnetic excitation. Generators with excitation from permanent magnets are low-power and are used to a limited extent on tractors, where only lighting devices are consumers of electricity.

 

Most alternators used on tractors today have electromagnetic excitation.

 

Generators are driven by the crankshaft of a diesel engine and convert mechanical energy into electrical energy. 15.3701 (G-309) alternating current generators are installed on tractor and combine diesel engines of the SMD-60 type.

 

A G-309 generator with a capacity of 1000 W is installed on the SMD-60 and SMD-62 engines, and a G-309K generator with a capacity of 400 W is installed on the SMD-64 engine. Generator 15.3701 produces electric current with a voltage of 14 V and is a non-contact five-phase electric machine of the same name with one-sided electromagnetic excitation and a built-in rectifier block BPV-12-100.

The generator consists of a stator 12, a rotor 26, an excitation coil, front 13 and rear 11 covers, a rectifier, a drive pulley 21 and impellers 22 and 10.

 

Stator 12 is made of a package of steel plates. On the inner surface of the stator there are ten teeth, each of which has a coil of the stator winding. Two coils are connected in series in phase. The ends of the phases are led out by flexible wires with tips.

 

The rotor 26 is made in the form of a six-pointed star from steel plates and is pressed onto the shaft 19.

 

The shaft 19 of the rotor is located in ball bearings 18 and 29 of a closed design with one-time lubrication. At the front end of the shaft, there is a peak driver 21, to which an impeller 22 is attached for cooling the generator, and at the rear end there is an impeller 10 that cools the rectifier unit. For this, ribs are placed on the body 31 and cover 11. The excitation winding 25 is attached to the front cover 13. One end is connected to the additional terminal of the generator and terminal D of the voltage regulator, and the other - to terminal III of the voltage regulator 4.

 

The rectifier unit installed on the back cover 11 consists of power and additional rectifiers, a voltage regulator unit and a switch for seasonal voltage regulation 32 "Winter-Summer". Structurally, the power and additional rectifiers are mounted in one housing. The voltage regulator unit and switch 32 are placed on cover 5.

 

In the body 9 of the rectifier, five diodes of reverse polarity are fixed, and in the plate 8 - five diodes of forward polarity. The inputs of the diodes are connected by buses to the outputs of the phase windings of the stator 27. The outputs of the diodes of the reverse polarity are connected to the "mass", and the diodes of the forward polarity are connected to the output terminal 1 of the generator. The additional rectifier consists of three forward-polarity diodes pressed into buses, which pairwise connect the forward and reverse-polarity diodes of the power rectifier. An additional rectifier provides automatic protection of the battery against discharge on the excitation winding of the generator when the diesel engine is not working. When the diesel engine is running, the current flows through the additional rectifier to the excitation winding 25 and the starter blocking relay.

 

The Y112B type integrated voltage regulator is a non-disassemble microcircuit. For its correct installation, there is a protrusion on the integrated device. The integrated device is cooled through a radiator made of strip aluminum. The integrated device has four terminals C, B, W and D in the form of contact pads. These pins are isolated from the integrated device. The marking of the terminals is applied to its plastic cover. The body of the integrated device is the fifth output - "ground". A resistor is connected between terminals B and D to supply current to the generator when excited from the battery. To improve the quality of regulation of the integrated device (in the absence of a battery), a filter capacitor K50-ZA (SF) is installed. Self-excitation of the generator without a battery occurs due to the residual induction of the excitation system.

 

When switch 32 is turned on in the "Winter" position, resistor K.2 is connected to terminal C of the integrated device by one terminal, and to the generator body ("mass") by the other. When the switch 32 is turned on in the "Summer" position, the resistor R 2 is disconnected from the generator circuit.

 

The generator works like this. Direct current from the positive terminal of the battery through terminal B, resistor R 1 and terminal D of the integrated unit flows to the excitation winding 25 of the generator, then to the terminal Ш, transistors and the "ground" of the integrated unit, and from there to the negative terminal of the battery. When an electric current passes through the excitation winding 25, a magnetic field is created around it. The magnetic flux crosses the sleeve 15 with the flange 14, the rotor 26 and the stator 12 with the windings 27 of the stator coil.

 

During the rotation of the shaft 19, the teeth and depressions of the rotor 26 are alternately located against each winding 27 of the stator. At the same time, the magnitude of the magnetic flux created by the excitation coil changes from the maximum to the minimum value. Under the action of changes in the magnitude of the magnetic flux in the stator windings, a variable electromotive force arises, which forms an electric current of alternating direction. Alternating current from the stator windings enters the rectifier. The power rectifier converts alternating current into direct current and goes to charge the battery and to other consumers. Direct current from the additional rectifier flows to terminal 2 of the generator and to winding 25 of the excitation coil.

 

 

 

Regular voltages

The frequency of rotation of the crankshaft of the engine, and therefore the rotor of the generator, varies widely. Since at the same time the speed of crossing the stator windings by magnetic lines of force also changes proportionally, according to the law of electromagnetic induction, the EMF induced in the windings changes accordingly, and therefore the voltage of the generator. From the same law it follows that it is possible to maintain a constant voltage (and this is necessary for the normal operation of consumers) by changing the magnetic induction inversely proportional to the rotation frequency. This is achieved by automatically changing the current in the excitation winding using a voltage regulator . For example, if the rotation frequency increases, the voltage regulator will accordingly reduce the current in the excitation winding, and therefore the voltage of the generator does not increase.

 

Voltage regulators (relay regulators) are divided into several types:

• vibrational
• contact-transistor
• transistor (contactless)
• integral (transistor, made according to integral technology)

 

At present, generator devices mainly use transistor and integrated voltage regulators.

In the transistor voltage regulator, the current in the excitation winding of the generator is controlled by zener diode 5. When the generator voltage exceeds the regulated voltage, the zener diode is electrically punched. The base of the transistor turns out to be connected to the "+" terminal of the source, the transistor closes, and the current flows only through the resistor P d . The voltage of the generator decreases, the zener diode closes, the transistor switches to the "Open" state, and an increased excitation current passes through it. As a result, the voltage increases again until the zener diode is broken, the process is repeated again.

 

The depicted circuit of the transistor voltage regulator is simplified. In practice, it includes two or three transistors, a large number of resistors, diodes and some other components.

 

Despite this, the dimensions of the transistor voltage regulator are several times smaller than those of the contact-transistor relay-regulator, and no adjustment is necessary in operation.

 

The overall dimensions of the Y112B voltage regulator, made in the form of an integrated microcircuit, allow it to be mounted on the cover of the generator.

 

 

 

Original.