Bosch_starter_alternator_catalogue(1).pdf

How to Use this Catalogue

Date

The date is listed in short code format,

i.e. Month/Year (01.98 = January 1998), with

an approximate manufacture/ introduction date

to last manufacture / sale date.

Example

0 120 006 001 is not available as a stock unit, but can be obtained from Germany upon request.

BX..... readily available as a stock item.

Alternator Systems

Design criteria

The following data are decisive for alternator design:

–Vehicle type and the associated operating condi-

tions,

– Speed range of the engine with which the alterna-

tor is to be used,

–Battery voltage of the vehicle electrical system,

–Power requirements of the loads which can be

connected,

– Environmental loading imposed on the alternator

(heat, dirt, dampness, etc.),

– Specified service life,

–Available installation space, dimensions.

The requirements to be met by an automotive alter-

nator differ very considerably depending upon appli-

cation and the criteria as listed above. Regarding

economic efficiency the criteria also vary along with

the areas of application.

It is therefore impossible to design an all-purpose

alternator which meets all requirements.

The different areas of application, and the power

ranges of the vehicle types and engines concerned,

led to the development of a number of basic models

which will be described in the following.

The different alternator sizes are identified by a letter

of the alphabet, and increase in alphabetical order.

A further important feature is the alternator or rotor

system (e.g., claw-pole alternator as a compact alter-

nator or alternator with compact diode assembly, or

with salient-pole rotor or windingless rotor).

This characteristic is identified by numbers or letters.

In addition, the various alternators are identified by

an alphanumeric code e.g., GC, KC, NC, G1, K1,

N1 for passenger cars, and K1, N1, T1 for commer-

cial vehicles and buses.

Further variations are possible with regard to the

type of mounting, the fan shape, the pulley, and the

electrical connections.

Table 1. Alternator types

Design

Application

Type No. of

poles

Compact Passenger cars,

GC, 12

motorcycles

KC,

Compact Passenger cars,

diode commercial vehicles,

assembly tractors, motorcycles

Passenger cars,

Electrical data and sizes

The vehicle size is not decisive for determining the

required alternator output power. This is solely a

function of the loads installed in the vehicle.

The selection of the correct alternator is governed

primarily by:

– the alternator voltage (14V/28V),

– the power output as a product of voltage and cur-

rent throughout the rotational-speed range,

– the maximum current,

– the cutting-in speed.

With these electrical data, it is possible to define the

electrical layout, and therefore the required alterna-

tor size.

K1,

commercial vehicles,

tractors, motorcycles

Alternators (continued)

Fig. 1: Alternator types

1. Compact claw-pole alternator (KC)

2. Claw-pole alternator with compact diode assembly (N1)

Alternators (continued)

Characteristic curves

Alternator performance

The characteristic performance of the alternator at

a variety of different speeds is shown by the

characteristic curves. Due to the constant

transmission ratio between alternator and engine,

the alternator must be able to operate at greatly

differing speeds.

As the engine takes the alternator from standstill up

to maximum speed, the alternator passes through

certain speeds. Each of these rotational speeds is

of particular importance for understanding the

alternator’s operation and each has therefore been

allocated a specific name.

Normally, the curves for alternator current and drive

power are shown as a function of the rotational

speed (Fig. 2).

The characteristic curves of an alternator are always

referred to a constant voltage and precisely defined

temperature conditions. For instance, an ambient

temperature of 80°C (or a room temperature of

23°C) is specified for the limit-temperature test.

Alternators (continued)

Characteristic curves

Current characteristic curve ( I )

n 0 0-Ampere speed

The 0-Ampere speed is the speed (approx.

1000min –1 ) at which the alternator reaches its rated

voltage without delivering power. This is the speed

at which the curve crosses the min –1 abscissa.

The alternator can only deliver power at higher

speeds.

n A Cutting-in speed

The cutting-in speed is defined as that speed at

which the alternator starts to deliver current when

the speed is increased for the first time. It is above

the idle speed, and depends upon the preexcitation

power, the rotor’s remanence, the battery voltage,

and the rate of rotational-speed change.

Characteristic curve of power input ( P 1 )

The characteristic curve of power input is decisive

for drive-belt calculations.

Information can be taken from this curve concerning

the maximum power which must be taken from the

engine to drive the alternator at a given speed.

In addition, the power input and power output can

be used to calculate the alternator’s efficiency. The

example in Fig. 2 shows that after a gradual rise in

the medium speed range, the characteristic curve for

power input rises again sharply at higher speeds.

This is due to the increased power required to drive

the fan at higher speeds.

n L Speed with engine idling

I L Current with engine idling

With the speed increasing, alternator speed n L is

reached with the engine at idle. This point is shown

as an area in Fig. 1 since the precise value depends

upon the transmission ratio between engine and

alternator. At this speed, the alternator must deliver

at least the current required for the long-term con-

sumers. This value is given in the alternator’s type

designation. In the case of compact-diode-assembly

alternators, n L =1500 min –1 , for compact alterna-

n N Speed at rated current

I N Rated current

The speed at which the alternator generates its

rated current is stipulated as n N = 6000 min –1 .

The rated current should always be higher than the

total current required by all loads together. It is also

given in the type designation.

Explanation of the type designation

Every Bosch alternator carries a rating plate contain-

ing type designation and 10-digit Part Number which

in the case of alternators always starts with 0 12...

... .

The type designation gives information on the alter-

nator’s most important technical data such as cur-

rent at engine idle and rated voltage etc.

n max Maximum speed

l max Maximum current

l max is the maximum achievable current at the alter-

nator’s maximum speed.

Maximum speed is limited by the rolling bearings

and the carbon brushes as well as by the fan. With

compact alternators it is 18,000 . . . 20,000 min –1 ,

and for compact-diode-assembly alternators 15,000

... 18,000 min –1 . In the case of commercial vehi-

cles, it is 8,000 ... 15,000 min –1 depending upon

alternator size.

Example of a type designation

K C (

) 14V 40-70A

Alternator size

(stator OD),

Compact-Alternator,

) Direction of rotation, clockwise,

14V Alternator voltage,

40A Current at n = 1800 min –1 ,

70A Current at n = 6000 min –1 .

tors n L =1800 min –1 due to the usually higher

transmission ratio.

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