Electricity: motive power systems – Battery-fed motor systems
Reexamination Certificate
1996-04-09
2002-05-07
Salata, Jonathan (Department: 2837)
Electricity: motive power systems
Battery-fed motor systems
Reexamination Certificate
active
06384551
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a control apparatus for an AC generator of a motor vehicle and more particularly to a control apparatus for an AC generator of a motor vehicle for changing over power supply to a high-voltage electric load driven at a higher voltage level than an ordinary one.
2. Description of Related Art
For having better understanding of the present invention, background techniques thereof will be described in some detail.
FIG. 6
is a circuit diagram showing a structure of a conventional control apparatus for an AC generator of a motor vehicle known heretofore such as disclosed, for example, in Japanese Unexamined Patent Application Publication No. 206848/1989 (JP-A-1-206848). Referring to the figure, the conventional control apparatus is comprised of an AC generator (alternating current generator)
1
driven by an internal combustion engine of a motor vehicle (not shown) and constituted by a field coil
102
for generating a rotating magnetic field and an armature coil
101
for generating an AC voltage under the action of the rotating magnetic field as generated, a rectifier
2
for full-wave rectification of the electric power generated by the AC generator
1
, an output change-over controller
7
for changing over the supply of the rectified output power of the rectifier
2
between a battery
4
and a high-voltage onboard electric load (e.g. high-voltage equipment of a motor vehicle)
5
, a key switch
6
which is closed for starting operation of the internal combustion engine by connecting a pulse terminal (i.e., terminal of positive polarity) of the battery
4
to the field coil
102
via the output change-over controller
7
for allowing a field current to flow through the field coil
102
, an engine control unit
8
(hereinafter referred to as the ECU for short) for outputting an ON/OFF signal to an excitation switch
72
for allowing supply of the output of the ECU
8
for a predetermined time, and a voltage regulator
3
for regulating the generated voltage by controlling the exciting current of the field coil
102
in dependence on the terminal voltage of the battery
4
.
The voltage regulator
3
is implemented in a circuit configuration described below. Connected between the plus terminal of the battery
4
and a grounded minus terminal
202
of the rectifier
2
are voltage division resistors
301
and
302
which serve as a first voltage detection means, wherein the terminal voltage of the battery
4
is detected as a divided voltage which makes appearance at a voltage dividing point A between the voltage division resistors
301
and
302
. Further, voltage division resistors
313
,
308
and
309
are connected in series between the plus terminal
201
and the minus terminal
202
of the rectifier
2
to serve as a second detection means and a third detecting means, respectively. The rectified output voltage making appearance at the plus terminal
201
is detected as a divided voltage appearing at a voltage dividing point B between a third detection means constituted by voltage division resistors
313
and
308
and the resistor
309
.
Connected between the excitation terminal of the positive polarity and a minus terminal
202
is a transistor
304
which has a collector connected to a load resistor
306
and an emitter connected to the ground potential, wherein the base of the transistor
304
is connected to the anode of a Zener diode
303
which has a cathode to which cathodes of diodes
310
and
311
having anodes connected to the voltage dividing points A and B, respectively, are connected in common. These diodes
310
and
311
serve for isolating the first detection means and the second detection means, respectively. Furthermore, a diode
312
is connected between the voltage dividing point C and the plus excitation terminal (i.e., terminal of positive polarity) of the field coil
102
. The diode
312
isolates the second detection means and the third detection means from each other.
Thus, it is apparent that each of the diodes
310
,
311
and
312
is constituted by a reverse blocking diode provided for isolating the detection means from each other. The Zener diode
303
is turned on (i.e., becomes conducting) when the voltages appearing at the circuit points A and B reach a predetermined level to thereby allow the transistor
304
to become conducting (or assume on-state).
Further, connected between the plus excitation terminal and the minus terminal
202
is an output transistor
305
having a collector connected to a diode
307
and an emitter connected to the ground potential, wherein the bases of the output transistor
305
is connected to the collector of the transistor
304
.
Parenthetically, the collector of the output transistor
305
is connected to the minus excitation terminal of the field coil
102
. Thus, the diode
307
is connected in parallel to the field coil
102
and serves for absorbing a surge of relatively long duration generated in the field coil
102
upon turning off the output transistor
305
.
Now, description will turn to operation of the AC generator control apparatus of the structure described above. Ordinarily, the output change-over switch
71
of the output change-over controller
7
is changed over toward the battery
4
, whereby the ordinary operation mode (battery charging operation mode) is set. On the other hand, when the output change-over switch
71
is changed over to the high-voltage onboard electric load
5
for a short time (e.g. about five minutes), a high-voltage operation mode is validated, which mode is validated for activating, for example, a defrosting/defreezing system for removing ice adhering or sticking to window glass of motor vehicles in winter or in severe cold districts. This operation mode is changed-over from the ordinary operation mode. The high-voltage onboard electric load
5
may be constituted by a heater, for example.
In the first place, the ordinary operation mode will be elucidated. When the key switch
6
is closed for starting operation of the internal combustion engine to thereby close the excitation switch
72
, field current flows to the field coil
102
from the battery
4
via the key switch
6
and the excitation switch
72
. Thus, the AC generator
1
is set to the state ready for generation of an AC power. Subsequently, when the AC generator
1
starts electric power generation upon starting of the engine operation, the voltage appearing at the plus terminal
201
of the rectifier
2
rises up. The battery
4
is charged with the rectifier output via the output change-over switch
71
, resulting in that the terminal voltage of the battery
4
rises up.
The terminal voltage of the battery
4
is detected in terms of a divided voltage resulting from the voltage division by the voltage division resistors
301
and
302
incorporated in the voltage regulator
3
. When the divided voltage making appearance at the voltage dividing point A between the voltage division resistors
301
and
302
reaches a turn-on voltage of the Zener diode
303
as the terminal voltage of the battery
4
increases, the Zener diode
303
becomes conducting, whereby the transistor
304
is turned on while the output transistor
305
is turned off to thereby interrupt the field current. By contrast, when the terminal voltage of the battery
4
lowers below the predetermined level mentioned previously, the Zener diode
303
is set to the non-conducting or off-state. As a result of this, the output transistor
305
is tuned on to allow the field current to flow.
In this manner, the transistor
304
is repetitionally turned on and off as the Zener diode
303
assumes the on- and off-states respectively, as a result of which the output transistor
305
is repeatedly turned on and off to effect an intermittent interruption control of the field current flowing through the field coil
102
for thereby regulating the terminal voltage of the battery
4
. In case a wire interconnecting the battery voltage detection terminal an
Salata Jonathan
Sughrue & Mion, PLLC
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