Charging system for an automotive engine

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG.
1, the same parts as FIG.
5 are identified with the same reference numerals as FIG.
5.
In the system of the present invention, a transistor T.
sub.
r4 is connected to the zener diode 12 in parallel.
The base of the transistor T.
sub.
r4 is connected to an output of a computer 20 through a terminal C.
The system is provided with a vehicle speed sensor 30, engine speed sensor 31, battery voltage sensor 32, idle switch 33 for detecting the idle operation of an automotive engine 34, and electric load sensor 40 comprising various load detecting switches such as a cooling radiator fan switch, headlamp switch, heater blower switch, air conditioner switch and rear window de-fogger switch.
As shown in FIG.
2, the computer 20 comprises waveform shaping circuits 41, 42 supplied with outputs of engine speed sensor 31 and vehicle speed sensor 30, respectively, an A/D converter 43 for the battery voltage sensor 32.
The computer 20 is provided with an input interface 44 supplied with output signals of waveform shaping circuits 41, 42, A/D converter 43, idle switch 33, and load sensor 40; CPU 45; ROM 46; RAM 47; clock generator 48 and output interface 49.
The computer operates to decide whether the vehicle driving condition is in a state necessary to charge the battery or not and produces an output from the output interface 49.
The operation will be described hereinafter with reference to FIGS.
3, 4a and 4b.
At a step 50, outputs of load sensor 40 are checked to detect operated switches, and at a step 51, load current (iL) is calculated based on the detected switches.
Engine speed (NE) is inputed at a step 52 and, at a step 53, generating current (iA) is obtained from a table in the ROM in dependence on the engine speed.
The load current (iL) is subtracted from the generating current (iA) at a step 54 to produce a charge/discharge current (i).
Thereafter, it is decided whether a set time elapses at a step 55.
When the set time does not elapse, mean charge/discharge current (I) and mean vehicle speed (V) are obtained at steps 56 and 57 respectively