2401102 - Introduction - CURRENT GENERATOR
COMPOSITION
The alternator is a rotary machine which transforms mechanical energy into electrical energy.
COMPOSITION
Like all electric machines, it basically consists of two parts: a rotor and a stator.The diagram below shows the rotor for an alternator with internal ventilation.
Rotor
The rotor is composed of a cylindrical magnetic core, concentric to the drive shaft, which has a toroid coil and two opposing magnetic impellers which are magnetized by the winding in the actual core.The impellers have six, claw-shaped, poles each, which interpolate reciprocally so that there are alternately six North poles and six South poles. There is therefore a single rotor winding which produces the e.m.f. for all the partial magnetic circuits.Stator
The diagram below illustrates the stator.
Stator
The stator consists of a ring-shaped laminated group joined by two or more axial welding seams on the outside. It usually has thirty six grooves which contain the three-phase winding made from insulated copper wire with vinyl acetate and is connected, as necessary, by a star or triangular connection.RECTIFIER BRIDGE
The diagram shows the rectifier bridge.
BRIDGE SPECIFICATIONS
The bridge consists of:
- Zener press fit diodes
- Diodes fitted on the dissipation plates electrically connected to the connection terminals with the phases.
- Dissipation plates.
- Large size dissipators.
- Phase insulation until the connection with the bridge through a rubber cable loom.
- Excess voltage limitation if the '+ battery' loads are disconnected guaranteed by the zener diodes.
Zener diodes
If the diodes are polarized directly they both allow the current to pass from the anode to the cathode (V+ I+): a zener diode therefore behaves like a normal silicon diode.If polarized inversely, initially the current does not flow from the cathode to the anode up to VZBeyond VZ a normal diode is ruined, but a zener diode, on the other hand, continues to work normally because its resistance in these conditions decreases sharply. A zener diode is therefore a voltage stabilizer diode. On cars the voltage ranges from 4.7 to 24 Volt. It is one of the most important components in the regulation unit.It is often used for protection against polarity inversion or excess voltage.ALTERNATOR WITH INTERNAL VENTILATION SPECIFICATIONS
The main feature of this type of alternator, with a 115 mm diameter stator, is having dual internal ventilation with the vanes inclined to guarantee the maximum flow of air and, at the same time, limit noise.Alternators with internal ventilation, for the same power supply, are smaller and lighter than types with external ventilation and satisfy all current application requirements (space in engine compartments is always at a premium). In addition to this, in terms of quality, these alternators are more reliable and durable than the best the competition currently has to offer on the market.In depth studies and research have made it possible to introduce all the devices, in production, designed to limit the noise produced by various components (fluid dynamics, mangetic, mechanical).TYPICAL VOLTAGE CURVE
The graph below shows a typical regulator voltage cuve.
TECHNICAL DATA
The table summarizes the types of alternator used on this vehicle.| - | 1.4 16v WITH HEATER | 1.4 16v WITH AIR CONDITIONING | 1.3 JTD WITH HEATER | 1.3 JTD WITH AIR CONDITIONING |
|---|---|---|---|---|
| ALTERNATOR' | A115IM 14V - 45/70A | A115IM 14V - 50/90A | TG8 14V - 75A | TG9 - 14V - 90A |
WIRING DIAGRAM
The diagram shows the operation of the alternator
OPERATION
With the alternator not working and the ignition key in the ON position, the Body Computer lights up the warning light in the instrument panel and sends a power supply to the voltage regulator incorporated in the actual alternator via terminal D+.In these conditions the energizing circuit (rotor) is enabled to earth by the regulator electronics.With the alternator rotating through the effect of the alteration in the number of revs and the mangetic field, a three-phase alternating volage is produced in the electrical circuit (stator) which, rectified by the diode bridge, can come out of terminal B+.When the upper fixed calibration level is reached (13.7 - 14.2 V) the battery is charged and it supplies the system.The Body Computer checks the efficiency of the alternator recharging system by measuring two parameters: the voltage signal coming from alternator terminal D+ and the engine rpm signal received at the CAN network from the engine management control unit.At the key on, as long as the voltage is below around 5.5V, the Body Computer signals that the charging is insufficient; when the voltage goes above 5.5V, the warning light goes out; if, on the other hand, with the engine moving (speed above 700 rpm), the voltage drops below the level of 4.5 V, the warning light comes on constantly. accompanied by a fault message in the display.SPECIFCATIONS
The main features of batteries used on new models are the mounting plates made from active materials produced through the calcium lead production technology which has replaced the older antimony- lead type.This involves a mechanical stretching process for a continuous lead band to reach the final productio of a grille covered in lead oxides for the positive poles and metallic lead only for the negative poles, instead of the use of casting machines to produce grilles for fusion.The use of a material such as lead-calcium-tin alloy guarantees a considerable reduction in the electrolysis during the operation of the accumulator (dissociation of the water into its components of hydrogen and oxygen) where the gases can escape resulting in reduced evaporation of the actual water with a drastic reduction in the maintenance required for this type of battery.
Battery electrical specifications
Lead accumulator, low maintenance type. Cover: EURODIN with ramp type sealing elements on cover; press-fit caps (one cap per element) with protection system against fluid penetration from the outside. Gas evacuation through caps with gas/liquid separation systemCover seal: heat welding.Attachment to the base: joined on four sides.Poles: lead bushes produced through cold-pressing with sealing labyrinth in the press-work area on the cover.Electrolyte level check: through the openings in the caps in the cover, checking the consistency between the indicator (dipstick) and the electrolyte level. The dipstick indicates the max. level allowed, therefore the electrolyte should just come into contact with the lower end of the dipstick. The min. level is reached when the electrolyte exceeds the top end of the separators and/or plates by 10 mm.Water gauge for checking min. electrolyte level and battery charge.No. of plates: 6 positive + 5 negative.Grille alloy: lead-calcium-tin.Separator thickness: 1.15 mm.Plate thickness: positive 1.80 mm; negative 1.60Electrolyte density: 1280 ± 10 g/dm3 at 25°C with battery 100% charged.Electrolyte density at 25° Celsius:
- 1280 g/litre 100 % of charge
- 1240 g/litre 75 % of charge
- 1200 g/litre 50 % of charge
- 1160 g/litre 25 % of charge
- 1120 g/litre drained
- 1110 g/litre totally drained.
CONTROL SYSTEM
This battery has an indicator for checking the battery which is a water gauge which makes it possible to qualitatively monitor the level of the electrolyte and the battery charge; this also allows the Customer to initially check the efficiency of the battery. this also allows the Customer to initially check the efficiency of the battery.This device consists of a transparent plexiglas cylinder: one end contains an indicator fixed to the battery cover; on the other end there is a drip tray, made from an acid-resistant material, drilled in such a way to allow the battery electrolyte to come into contact with a green coloured ball which is housed in the drip tray and can slide along a plane inclined towards the centre of the area of the cylinder.To sum up, the colour of the indicator reflects the state of the battery charge as set out in the table below.| CONDITION 3 | CONDITION 2 | CONDITION 1 | |
|---|---|---|---|
| Information visible | Light, bright colour | Dark colour with green area in the centre | Dark colour with green area in the centre |
| Electrolyte level | Below minimum | Correct | Correct |
| State of charge | Indeterminate | Battery discharged | from 55% to 100% |
| Action to undertake | Top up electrolyte with distilled water | Recharge the battery | No action |
This device:
- does not give readings concerning a possible internal short circuit;
- the density of the electrolyte varies with the temperature;
- a prolonged stop could halt the mixing process of the reagents and thereby lead to a measurement which could refer to the surface layers only.
- if the electrolyte level is low then there are no reliable readings.
CAP
In low maintenance type batteries with lead-calcium-tin elements the seal is guaranteed by the press-fit caps with an anti-penetration system with a gas evacuation device through the actual caps.The caps which allow the escape of the gases produced in the battery prevent the leakage of liquid. The cap consists of:
- The cap casing: it acts as to prevent liquids escaping, but allows gas to escape through special openings.
- The labyrinth: it prevents the particles which are released during the operation of the battery from obstructing the special diaphragm.
- The semi-pervious diaphragm: thanks to a special layer of PTFE (poly-tetra-fluoro-ethylene) it prevents the escape of liquid, allowing the gases which are produced during the normal operation of the battery to pass through.
BATTERY TECHNICAL SPECIFICATIONS
The table summarizes the main battery technical data.| BATTERY | 1.4 16v WITH HEATER | 1.4 16v WITH AIR CONDITIONING | 1.4 16v 'COLD COUNTRIES' | 1.3 JTD |
|---|---|---|---|---|
| CAPACITY | 40 Ah | 50 Ah | 60 Ah | 50 Ah |
| INTENSITY | 200 A | 250 A | 380 A | 350 A |
BATTERY DISCHARGE IN REST CONDITIONS
Correct battery dimensions for model / trim level have been calculated to take into account power uptake when the ignition is switched off.This absorption should not exceed 0.6 mA for each Ah of battery capacity; this is to ensure that, if the vehicle has been left for one month with all the consumers not controlled by the ignition switched on, residual battery capacity is half of nominal capacity, i.e. enough charge is left to start up the engine under normal environmental temperature conditions.The table below gives several examples.| Battery | Max. absorption |
|---|---|
| 40 Ah | 24 mA |
| 50 Ah | 30 mA |
| 60 Ah | 36 mA |
CHECKING/TOPPING UP BATTERY FLUID LEVEL
Undo the caps on the battery cover or remove the cap edges (2) and remove the caps which are a press-fit in each individual cell.In the Max Level maximum condition (11), the electrolyte should barely come into contact with the lower end of the dipstick (3), positioned inside the battery and visible through the openings in the cover in each cell producing the so-called 'meniscus effect'.In the Min Level minimum condition (12), the electrolyte should exceed the upper part of the partitions and/or the plates by around 10 mm.
CHECKING/TOPPING UP BATTERY FLUID LEVEL
To check this condition, immerse a clean stick, made from a non metallic material (e.g. wood, glass, plastic), into the electrolyte until it touches the top of the partitions and/or plates, measuring the height of the electrolyte.It remains understood that, in order to measure the level of the electrolyte, the battery should be positioned on an even surface and all the cells should be visible from above; if this is not the case, or if this is impossible, the battery should be removed from its housing in the vehicle.The operations of checking the electrolyte level and, if necessary, topping it up through the individual battery cell openings, should not be carried out by the Customer, but by trained Network personnel as part of the Planned Maintenance Programme every 20,000 km.WATER GAUGE
Two types of information are provided;
- electrolyte level;
- battery charge.
OPERATION
The operating principle of this device is based on the contact between the drip tray and the battery fluid.The ball has been designed in such a way that, at a given electrolyte density value, it rises along an inclined plane and reaches the transparent surface of the indicator, colouring the centre of this area green: CONDITION 1.When the density of the electrolyte decreases (battery run down), the ball moves from the centre and the light is subject to refraction to the extent that the colour in the centre of the indicator darkens: CONDITION 2.When the fluid no longer bathes the cylinder casing, the ball descends completely and the area in the centre appears even lighter: CONDITION 3.