Cars
[ A - A ] [ A - B ] [ B - F ] [ F - F ] [ F - J ] [ J - L ] [ L - M ] [ M - M ] [ M - O ] [ O - P ] [ P - S ] [ S - W ]
Links:
Swiss Car Sightings - car wallpapers images archives with 1600x1200 pixels resolution
Top Free Stuff Sites - cool wallpapers, ringtones for your mobile!
GENERATORS of the alternating CURRENT PURPOSE(ASSIGNMENT).
The generator is the basic source of electric energy of systems of the power supply, providing a feed(meal) of all consumers and a charge of the storage battery at work of the engine. To generators the following requirements are showed: simplicity of a design; durability and reliability in operation; small dimensions, weight and cost; the big specific capacity (capacity on 1 kg of weight); an opportunity of maintenance of a charge storage batteries at small frequency of rotation of a cranked shaft of the engine in a mode of idling. To the listed requirements in the greater degree satisfy only generators of an alternating current with the built - in silicon diodes, therefore they have found wide application on modern automobiles. The automobile generator of an alternating current - three-phase, synchronous, with electromagnetic excitation, at which frequency ... Proportional to frequency of rotation of a rotor of the generator. Such generators in comparison with generators of a direct current it is easier on a design, have smaller overall dimensions and weight at the same capacity, more reliable, and the charge on windings approximately in 2.5 times is less. In generators of an alternating current there is no collector, instead of a complex(difficult) winding of an anchor is applied the winding is technologically simple, the winding of excitation consists of one coil. Specific capacity of generators of a direct current does not exceed 45 , and generators of an alternating current reaches(achieves) up to 143 (266). Absence of a collector in generators of an alternating current allows to raise(increase) the maximal frequency of rotation of a rotor up to 12 thousand rev/min. Such design of the generator allows to raise(increase) frequency of rotation of a rotor of the generator and at work of the engine in a mode of idling. Therefore generators in this power setting develop up to 40 % of rated power that improves a charge of batteries. the GENERATOR. Generator G250 and his(its) updating, and also generators G266-271,272,286 concern to generators with electromagnetic excitation and the silicon diodes, mounted in the block of the generator. In these generators between two covers and by means of coupling screws fix the core , being which for reduction of heating by vortical currents type(collect) from the thin steel plates isolated from each other is delicious . a surface has eighteen on which it is strung eighteen coils of a winding . Coils are distributed(allocated) on three phases and included under the circuit "star", and in the generator Under the circuit "triangle". In each phase it is included on six consistently connected coils. The ends of coils of phases are joined(attached) to three clips of the block of silicon diodes of the rectifier. All diodes are connected to connecting trunks. During work of the generator in coils of a winding it is induced ..., under which action on a winding of excitation and in a circuit of the connected consumers the current proceeds. The rotor consists of two steel six-polar tips executed of soft steel. Tips of one half of rotor with northern magnetic polarity enter between tips of second half of rotor with southern magnetic polarity. A rotor rotates in two ball bearings established in covers. The coil of a winding of excitation is strung on the steel cartridge located between polar tips. Both ends of a winding are soldered to two copper contact rings, established on cartridges. Two graphite brushes of the generator are established in and nestle on contact rings springs. In generators G221, 250 and 271 the brush isolated from the case is connected by a conductor with clip other brush connected to the case of the generator. In generators G272, 266 and 286 both brushes are isolated from the case and connected with clips . Polar tips the cartridge and cartridges of contact rings on a corrugated surface of a shaft of a rotor. Covers and the generator have for movement of air created of a pulley. On a cover are established minus a clip - (the screw, screwed in a cover) and isolated from the case a clip +. Generators of series 250 (250-1,-1,-1,-1 etc.) differ from each other pulleys. In generator G250-ZH1 the paw of fastening is displaced. Generator G286 has a design similar to a design of generators G250, 271, 272, 266, but it is more dimensions and weight. The winding is connected under the circuit "triangle" that allows to reduce section of conductors of a winding and dimensions . Specification of generator G221, 250, (250-1,-1,-1,-1), 266, 271, 272 and 286. On 3940-71 for the generators designed after January, 1 1973, rated voltage accept 14 and 28 In. The alternating current of the generator will be transformed in constant by the rectifier collected under three-phase two half-period circuit on six silicon diodes. A design and the electric circuit the block such as . The block consists of three , established on the plastic basis and two connecting trunks. Each section of the block consists of aluminium casting with edges (heat-conducting path) in which two jacks are collected -n transitions diodes. In one jack -n transition has on the case a ?-zone, and in the friend a n-zone. Opposite zones of transitions have conclusions which are soldered to connecting trunks. The minus trunk the block is connected to the case of the generator, and is isolated from the case and connected to a clip "+". Each section has a clip to which one of the ends of a phase winding is connected. the block such as generator G221 consists of six diodes VA-20, which (on three pieces) in a cover of the generator and special a plate - heat-conducting path (holder). Diodes are issued in two executions(performances)- direct and return polarity. For difference of diodes cases of the diode of direct polarity it is painted in red color, and the diode of return polarity- black. Generator G221 differs from generator G250 and others basically that the winding has a zero conclusion 85 which is connected to the relay of the control of a charge. Figure 67 is a symbol of a conclusion of a winding of excitation, and figure a 30-conclusion from the rectifier.
PRINCIPLE of WORK of the GENERATOR.
Polar tips of magnetic system of the generator and the cartridge of a rotor have the small residual magnetism providing ... Nominal in a winding only at very big frequency of rotation of a shaft of a rotor. At the closed contacts of the switch of ignition the winding of excitation of the generator is connected to an accumulator room and the current which is taking place on it(her), causes magnetization of a rotor. The most part of a magnetic stream of a rotor becomes isolated through the core , and other part of a magnetic stream dissipates outside of the core and does not participate in prompting . .. With. In a winding . At rotation of a rotor under everyone the core passes that northern, South Pole of a rotor therefore the magnetic stream which is taking place through , changes the direction and size. Thereof there is a crossing coils of a winding magnetic power(force) lines and in them is induced . . With. A variable direction. .. With. Creates a three-phase alternating current which by means of silicon diodes is straightened in a direct current. . . With. , in coils of a winding , grows at increase of a magnetic stream of excitation and frequencies nP rotations of a rotor =n, Where With - constant factor for the given generator. At the switched - off external circuit owing to insignificant force of a current in a winding the power failure in it(her) will be a little, therefore the pressure(voltage) of generator UG can be counted equal to his(its) size ... U=E=np/ The pressure(voltage) of generator UG at the included external circuit will be less than it(him) ... With on size of a power failure in 6 (I R) U=-I Rc
CHARACTERISTICS of GENERATORS
Properties of automobile generators of an alternating current are defined(determined) by a number(line) of characteristics which represent dependence between any two sizes at the constant others. Let's consider dependence of change of the straightened pressure(voltage) of generator Ug on frequency of rotation n a rotor, at work of the generator without loading (I=0) and at a rated load (I=IN). From the diagram (1 ) it is visible, that the pressure(voltage) of the generator grows at increase of frequency of rotation of a rotor, and a point of crossing of dependences U=f (n) with a line of rated voltage UN define(determine) initial frequency of rotation n0 and nN accordingly at work of the generator without loading and with a rated load. Frequencies of rotation n0 and nN are control and are specified in characteristics. From the diagram also it is visible, that the generator develops a pressure(voltage) much more nominal and therefore all automobile generators work with the regulators of a pressure(voltage) varying force of a current in a winding of excitation and consequently, and a magnetic stream of excitation at change of frequency of rotation np a rotor, that is necessary for constancies of a pressure(voltage) of the generator. On 1 dependence of change of force of a current of loading I of the generator on frequency of rotation of a rotor np is shown at constant values of straightened pressure(voltage) U and forces of a current of excitation of generator Iv. The design of generators of an alternating current allows to raise(increase) transfer number from the engine to the generator, and therefore frequency of rotation of a rotor of the generator at the minimal frequency of rotation n (idling) of a cranked shaft of the engine is chosen above initial frequency of rotation n0. Hence at n (idling) of the engine of the generator will give a current that improves conditions under a charge of an accumulator room of batteries and raises term of its(her) service. The circuit of connection of devices for removal of the given characteristics is shown on rice 1. The maximal force of current Imax of the generator at the big frequency of rotation of a rotor exceeds nominal size IN. However thus the generator will not be, as the stream of the cooling air blown through the generator by the fan is sharply increased. Generators of an alternating current have property the maximal force of a current of loading that prevents overheating a winding and diodes of the rectifier, and necessity of installation of the terminator of force of a current for an electric circuit a generator - accumulator room the battery therefore is excluded. With increase of force of a current of loading force of a current in coils of a winding grows. Hence, the magnetic stream and as it(he) counteracts a magnetic stream of a rotor the resulting magnetic stream which is becoming isolated through the core , decreases grows also. In result the size of the magnetic stream crossing the coils of windings is reduced, and in them is induced less . . With. Besides the increase of frequency of rotation of a rotor is accompanied by increase of frequency of a current in coils of a winding , that increases inductive resistance of winding XL=2fL. Thus, owing to decrease(reduction) . . With. In coils of a winding at increase of loading of the generator and increase resistance of a winding with increase of frequency of rotation of a rotor the maximal force of a current of the generator i.e. when force of a current reaches(achieves) nominal is limited, curve I smoothly passes in a horizontal straight line.
REPAIR of GENERATORS.
Bad contact between brushes and contact rings of a rotor Arises at pollution and contact rings, the big deterioration of brushes of contact rings, reduction of pressure of springs by brushes and lag of brushes in . At such malfunctions resistance in a circuit of excitation and therefore, capacity of the generator decreases raises. The pressure(voltage) of the generator up to given reaches(achieves) only at the raised(increased) frequency of rotation of a rotor. For elimination of malfunction remove and check a condition of brushes and contact rings of a rotor. If necessary wipe their cloth moistened with gasoline. The oxidized surface of rings glass granularity 100-140; the worn out rings pierce. Brushes freely should move in . The brushes which have been worn out up to height less 7 mm, replace. Pressure of a spring upon a brush within the limits of 180-260 . definitions of pressure of a spring of each brush should be necessary to remove from one brush, and other brush which has stayed in , the Brush will press a cup weights to enter in and when she(it) will act from on 2 mm measure indications of an arrow(a pointer) of weights. This size also will be that pressure with which the spring presses a brush to a contact ring of a rotor . check pressure of a spring of other brush. BREAKAGE of the WINDING of EXCITATION arises in places of the soldering of the ends of a winding to contact rings more often. Breakage in a winding of excitation is defined(determined) by an ohmmeter or a control lamp. This malfunction is eliminated by the soldering soft solders. When breakage has taken place inside the coil, make replacement or rewind of the coil. At breakage of a winding of excitation in a winding it will be induced . .. No more than 5 In, caused by residual magnetism of steel of a rotor. SHORT CIRCUIT of the WINDING of EXCITATION ON the CASE of the ROTOR occurs at destruction of isolation of a winding. Closed on the case and on it(her) will not pass a current In result the generator will not work. Short circuit of a winding on the case define(determine) a control lamp at a pressure(voltage) 220-500 In. One conductor connect to any contact ring, and another- the core or in gross of a rotor. The lamp will burn, when the winding is closed on the case. If it is impossible to isolate a winding from the case, her(it) replace. SHORT CIRCUIT In the COIL of the WINDING of EXCITATION arises owing to destruction of isolation of a wire of a winding at or mechanical damage. In result resistance of a circuit of a winding of excitation decreases. Hence, the temperature of a winding that cause the even greater destruction of isolation of a wire and short circuit among themselves a lot of coils of the coil will be raised. At work of the generator with regulators 127 and 380 the current of excitation of the generator becomes isolated through contacts of a regulator. Hence, at decrease(reduction) of resistance of a winding of excitation through contacts of a regulator will pass a current more allowable and consequently between contacts arises strong , that will speed up oxidation and erosion of a working surface. If the generator works with transistor relays - regulators at the greater force of a current of excitation there is an overheating the target transistor that can result in his(its) breakdown. short circuit define(determine) measurement of resistance of the coil by means of an ohmmeter which indications are compared to size of resistance. SHORT CIRCUIT of WINDING ON the CASE arises owing to mechanical or thermal damage of isolation of a winding. At this malfunction capacity of the generator owing to short circuit of faulty phase windings with the case and diodes of the rectifier of the generator is considerably reduced. This malfunction define(determine) a control lamp at a pressure(voltage) 220-500 In, connection of one wire on the core , and another on any conclusion of a winding . The lamp burns only at short circuit of a winding on the case. Check of a winding are made at the switched - off block of the rectifier from the ends of phases. Defects of the coil of a winding are replaced new. BREAKAGE In the CIRCUIT of PHASE WINDING causes deenergizing a phase that will increase resistance in a circuit of other phases. At such malfunction capacity of the generator is reduced, and the storage battery will not be charged completely. In case of breakage of a circuit of two phases all circuit of a winding is switched off and the generator will not work. In the disassembled generator for definition of breakage in a phase winding serially it is necessary to connect to an accumulator room through a bulb on two phases of a winding. Presence of breakage switches off a circuit, and the lamp will not burn. SHORT CIRCUIT In COILS of WINDING arises at destruction of isolation of a winding. In short-circuited coils will pass a current of short circuit of the big force that will strengthen overheating the coil and the further destruction of isolation of a winding. At such malfunction considerably reduces capacity of the generator, and at inclusion of loading the pressure(voltage) of the generator sharply decreases. Destroyed it is easy for isolation of a winding to define(determine) survey of its(her) condition in the disassembled generator. Defects of the coil of a winding are replaced new. short circuit in a winding also define(determine) with the help -1. In the plastic case induction and -alarm devices are established. Steel cores and devices it is reeled - up on one winding. The winding of the -alarm device is closed by a neon lamp. The winding of the induction device is included through contacts of the electromagnetic breaker to two clips. In parallel contacts of the breaker it is included the condenser. At check of a winding the device establish so that the groove between the core settled down between air backlashes of cores and -alarm and induction devices. Then a winding of the induction device connect to a source constant or an alternating current a pressure(voltage) 12 In. The current in a circuit of the induction device will cause vibration of contacts of the breaker, and consequently, a pulsation of a magnetic stream in the core and the core the generator. As a result of crossing by power(force) lines in the coil of a winding it will be induced . .. If in the coil there are short-circuited coils, induced . .. Will create an alternating current which will cause the variable field. This magnetic field, becoming isolated through the core of the -alarm device, induces in a winding . .. Under which action there will be a luminescence of a lamp. If the checked coil of a winding has no short circuit in it(her) the current and a magnetic field will not be created. Hence, in a winding of the -alarm device will not be . .. And the neon lamp will not shine. Except for named, there are also malfunctions of mechanical character, for example, deterioration and destruction of bearings, deteriorations a shaft of a rotor, development flutes of a shaft and a pulley, damage of a groove on a shaft and in nuts etc. Revealing and elimination of similar malfunctions does not represent the big difficulties. SHORT CIRCUIT of the CLIP "+" ON the CASE occurs owing to destruction of isolation of a clip or isolation of the wire connected to this clip. At such malfunction of the generator and the storage battery will be the case of the automobile. Short circuit of the generator will cause sharp increase of force of a current in a winding and diodes the block, and therefore there will be a thermal destruction of isolation of a winding and breakdown of diodes the block. Defective isolation of a clip replace new. The damaged(injured) windings and the block of diodes are replaced. BREAKDOWN of DIODES VYPRJAMITEL'NOGO of the BLOCK occurs at a current of the big force, increase of a pressure(voltage) of the generator norms and mechanical damage are higher. In the punched diode resistance practically will be equal to zero. In this case it(he) will carry out(spend) a current in both directions that will cause short circuit of phases of a winding . result of it capacity of the generator and the storage battery will decrease will not be charged completely. At the idle engine the storage battery will be unloaded through the punched diodes the block. At breakdown, and also at breakage of a circuit of diodes owing to decrease(reduction) of capacity of the generator there is a sharp reduction of a pressure(voltage) of the generator at the moment of inclusion of loading. Check of diodes on breakdown and breakage of a circuit make a control lamp capacity 1 from an accumulator room of batteries a pressure(voltage) 12 ( 24 ) In or an ohmmeter. The diode serviceable if the lamp burns only in one of cases of connection to . (2, ) the Diode has breakage of a circuit if the lamp will not burn in both cases of connection of wires. The diode has short circuit (is punched), if the lamp burns at any connection of wires. Check of serviceability of diodes the block of the generator make under the circuit given on rice 2 in. For check of the diodes connected to the trunk, connect to it(her) a wire from a conclusion "+" the storage battery, and other wire connected to a conclusion "-" batteries, serially concern clips of the block. At a serviceable condition of a circuit of the diode the lamp will burn. The lamp does not burn, if in a circuit of the diode there is a breakage. Then connect to the trunk a wire from a conclusion "-" an accumulator room of batteries, and other wire serially concern clips of the block. At a serviceable condition of diodes the lamp does not burn. In case of breakdown of the diode the lamp will burn. Also check the diodes connected to the trunk. In blocks at the faulty diode replace section of the block. At test of the serviceable diode his(its) resistance will be no more than 200 Ohm, and at change places of the ends of conductors from an ohmmeter to conclusions of the diode - some hundreds whom. In the punched diode resistance is equal to zero, and at breakage to conductor - infinity.
MAINTENANCE SERVICE of the GENERATOR.
Check an inhaling(a prolongation) of details of fastening of covers and a pulley of the generator. Rotation of a rotor by hand check ease of rotation. Remove and define(determine) a degree of deterioration and ease of their moving in , and also a condition of contact rings of a rotor. At the disassembled generator check a winding and a winding of a rotor on breakage, short circuit and short circuits on the case, and also check serviceability of the block of the rectifier. Make check of the generator for definition of frequency of rotation at which the generator is raised up to rated voltage without loading and at a rated load. Check and if necessary to adjust a regulator of a pressure(voltage), the relay of protection and the relay of the control of a charge. Check of serviceability of the generator and relays - generators make on automobiles with application of portable devices or in shop on the specialized stands. For a drive of generators stands are equipped with electric motors or asynchronous three-phase electric motors and a variator allowing smoothly to adjust frequency of rotation about 5000?/minutes. The circuit of inclusion of devices at test of the generator is shown on rice 3. Frequency of rotation of a rotor of the generator measure a tachometer. Loading in an external circuit of the generator create a rheostat and supervise the ammeter. A pressure(voltage) of the generator supervise the voltmeter. The circuit of excitation of the generator is connected by the switch to an accumulator room . Force of a current in a circuit of excitation also is supervised by the ammeter. CHECK of the GENERATOR WITHOUT LOADING. Fix the checked generator on the stand and connect his(its) rotor to shaft of the electric motor. Then the switch connect a circuit of a winding of excitation of the generator to an accumulator room . The switch disconnect a circuit of loading. Then include the electric motor of a drive of the generator and smoothly increase rotation of a rotor of the generator, supervising her(it) under the indication of a tachometer. As soon as the pressure(voltage) of the generator will reach(achieve) nominal , take readings of a tachometer and compare them to specifications. The generator count serviceable if frequency of rotation of a rotor at rated voltage does not exceed , specified. For example, the pressure(voltage) of serviceable generator G250 will reach(achieve) 12,5 In at 950 rev/min. The ambassador make check of the generator under loading. CHECK of the GENERATOR UNDER LOADING. The switch include a circuit of loading and at a rotating rotor of the generator increase force of loading, observing for indications of the ammeter and the voltmeter. Nominal pressure(voltage) it is supported thus by increase of frequency of rotation of a rotor. As soon as force of a current of loading will reach(achieve) necessary at nominal size of a pressure(voltage), take readings of a tachometer. The generator count serviceable if necessary force of a current of loading at rated voltage is reached(achieved) at frequency of rotation of the rotor, not exceeding size specified. For example, for generator G250 at force of a current of loading 28 And and a pressure(voltage) 12,5 In frequency of rotation of a rotor should be no more than 2100 rev/min.
