U.S. patent application number 09/780905 was filed with the patent office on 2001-08-16 for battery charging apparatus.
Invention is credited to Ayuzawa, Takuma, Horibe, Hiroyuki, Suzuki, Hidetoshi, Yamaguchi, Mashaiko.
Application Number | 20010013768 09/780905 |
Document ID | / |
Family ID | 18562342 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013768 |
Kind Code |
A1 |
Suzuki, Hidetoshi ; et
al. |
August 16, 2001 |
Battery charging apparatus
Abstract
A battery charging apparatus comprising a controller to control
on-off controllable switch elements of an AC power source output
short circuit and including a first control section to control the
on-off controllable switch elements so that they are at an on-state
when an instantaneous terminal voltage of a battery exceeds a first
set value and a second control section to control the on-off switch
elements so that they are at an on-state when an average voltage of
the battery exceeds a second set value and serving to control them
when a power source switch is closed.
Inventors: |
Suzuki, Hidetoshi;
(Numazu-shi, JP) ; Horibe, Hiroyuki; (Numazu-shi,
JP) ; Ayuzawa, Takuma; (Numazu-shi, JP) ;
Yamaguchi, Mashaiko; (Numazu-shi, JP) |
Correspondence
Address: |
PEARNE & GORDON LLP
526 SUPERIOR AVENUE EAST
SUITE 1200
CLEVELAND
OH
44114-1484
US
|
Family ID: |
18562342 |
Appl. No.: |
09/780905 |
Filed: |
February 9, 2001 |
Current U.S.
Class: |
320/134 |
Current CPC
Class: |
H02J 7/1484
20130101 |
Class at
Publication: |
320/134 |
International
Class: |
H02J 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 16, 2000 |
JP |
38638/2000 |
Claims
What is claimed is;
1. A battery charging apparatus comprising a magneto AC generator,
a rectifier circuit having input terminals connected to output
terminals of said generator and output terminals to which a battery
is connected, an output short circuit having on-off controllable
switch elements and shorting said output terminals of said magneto
AC generator when said switch elements are at an on state and a
controller to control said switch elements of said output short
circuit in accordance with a terminal voltage of said battery, said
controller including a first switch control section to control said
switch elements of said output short circuit to be turned on when
an instantaneous value of said terminal voltage of said battery
exceeds a first set value, an average voltage detection circuit to
detect an average value of said terminal voltage of said battery, a
second switch control section to control said switch elements of
said output short circuit to be turned on when said average value
of said terminal voltage of said battery exceeds a second set value
and control change-over means to change controls by said first
control section and said second control sections so that said
switch elements are controlled by said second control section when
an electric power is supplied from said battery to a load and so
that said switch elements are controlled by said first control
section when said load is cut from said battery.
2. A battery charging apparatus comprising a magneto AC generator,
a rectifier circuit having input terminals connected to output
terminals of said generator and output terminals to which a battery
is connected, an output short circuit having on-off controllable
switch elements and shorting said output terminals of said magneto
AC generator when said switch elements are at an on-state and a
controller to control said switch elements of said output short
circuit in accordance with a terminal voltage of said battery, said
controller including a first switch control section to control said
switch elements of said output short circuit to be turned on when
an instantaneous value of said terminal voltage of said battery
detected at both ends of said battery exceeds a first set value, an
average voltage detection circuit to detect an average value of
said terminal voltage of said battery at both ends of a load
connected through a power source switch to said battery and a
second switch control section to control said switch elements of
said output short circuit to be turned on when said average value
of said terminal voltage of said battery exceeds a second set
value, said first set value is set within a range over which said
battery and said load are not adversely affected, so as to be
higher than said instantaneous value of said terminal voltage of
said battery when said average value of said terminal voltage of
said battery reaches said second set value.
3. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and wherein said controller further
includes acceleration state detection means to detect an
acceleration state of said internal combustion engine from a
revolution of said internal combustion engine and an opening degree
of a throttle and set value change-over means to change said second
set value to a higher value when said acceleration state detection
means detects said acceleration state of said internal combustion
engine.
4. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and said controller further
including deceleration state detection means to detect a
deceleration state of said internal combustion engine from a
revolution of said internal combustion engine and an opening degree
of a throttle and set value change-over means to change said second
set value to a lower value when said deceleration state detection
means detects said deceleration state of said internal combustion
engine.
5. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and said controller further
including acceleration/deceleration state detection means to detect
an acceleration state of said internal combustion engine and a
deceleration thereof from a revolution of said internal combustion
engine and an opening degree of a throttle and set value
change-over means to change said second set value to a higher value
when said acceleration/deceleration state detection means detects
said acceleration state of said internal combustion engine and to
change said second set value to a lower value when said
acceleration/deceleration state detection means detects said
deceleration state of said internal combustion engine.
6. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator while coils of said generator are
constructed so as to be cooled by a lubrication oil of said
internal combustion engine and said controller further including
oil temperature detection means to detect a temperature of said
lubrication oil of said internal combustion engine and set value
change-over means to change said second value to a higher value
when said temperature detected by said oil temperature detection
means exceeds a set value.
7. A battery charging apparatus comprising a magneto AC generator,
a rectifier circuit having input terminals connected to output
terminals of said generator and output terminals to which a battery
is connected, an output short circuit having on-off controllable
switch elements and shorting said output terminals of said magneto
AC generator when said switch elements are at an on-state and a
controller to control said switch elements of said output short
circuit in accordance with a terminal voltage of said battery, said
controller including a first switch control section to control said
switch elements of said output short circuit to be turned on when
an instantaneous value of said terminal voltage of said battery
exceeds a first set value, an average voltage detection circuit to
detect an average value of said terminal voltage of said battery,
set value arithmetical operation means to arithmetically operate a
second set value providing a limit value of said average value of
said battery terminal voltage in accordance with an atmospheric
temperature of said battery, a second switch control section to
control said switch elements of said output short circuit to be
turned on when said average value of said terminal voltage of said
battery exceeds said second set value and control change-over means
to change controls by said first control section and said second
control sections so that said switch elements are controlled by
said second control section when an electric power is supplied from
said battery to a load and so that said switch elements are
controlled by said first control section when said load is cut from
said battery and said set value arithmetical operation means being
constructed so that said second set value gets higher when said
atmospheric temperature is low and gets lower as said atmospheric
temperature increases.
8. A battery charging apparatus comprising a magneto AC generator,
a rectifier circuit having input terminals connected to output
terminals of said generator and output terminals to which a battery
is connected, an output short circuit having on-off controllable
switch elements and shorting said output terminals of said magneto
AC generator when said switch elements are at an on-state and a
controller to control said switch elements of said output short
circuit in accordance with a terminal voltage of said battery, said
controller including a first switch control section to control said
switch elements of said output short circuit to be turned on when
said terminal voltage of said battery detected at both ends of said
battery exceeds a first set value, an average voltage detection
circuit to detect an average value of said terminal voltage of said
battery at both ends of a load connected through a power source
switch to said battery, set value arithmetical operation means to
arithmetically operate a second set value providing a limit value
of said average value of said battery terminal voltage in
accordance with an atmospheric temperature of said battery and a
second switch control section to control said switch elements of
said output short circuit to be turned on when said average value
of said terminal voltage of said battery detected by said average
voltage detection circuit exceeds said second set value, said first
set value is set within a range over which said battery and said
load are not adversely affected, so as to be higher than said
instantaneous value of said terminal voltage of said battery when
said average value of said terminal voltage of said battery reaches
a maximum value of said second set value.
9. A battery charging apparatus as set forth in either of claims 1,
2, 7 and 8 and wherein said first switch control section comprises
an overvoltage detection circuit including a first voltage divider
resistor having one end connected to a positive terminal of said
battery, a Zener diode provided between said first voltage divider
resistor and a negative terminal of said battery with an anode
faced to said negative terminal of said battery and connected in
series to said first voltage divider resistor and a second voltage
divider resistor provided between the other end of said first
voltage divider resistor and said negative terminal of said battery
and connected in series to said Zener diode and said first voltage
divider resistor to generate an overvoltage detection signal by
conducting said Zener diode when said instantaneous value of said
battery terminal voltage exceeds said first set value and a switch
element trigger circuit to apply a switch trigger signal to said
switch elements of said output short circuit for turning them on
when said overvoltage detection circuit generates said overvoltage
detection signal.
10. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and said controller further
including acceleration state detection means to detect an
acceleration state of said internal combustion engine from a
revolution of said internal combustion engine and an opening degree
of a throttle and set value change-over means to change said second
set value to a higher value when said acceleration state detection
means detects said acceleration state of said internal combustion
engine and wherein said first switch control section comprises an
overvoltage detection circuit including a first voltage divider
resistor having one end connected to a positive terminal of said
battery, a Zener diode provided between said first voltage divider
resistor and a negative terminal of said battery with an anode
faced to said negative terminal of said battery and connected in
series to said first voltage divider resistor and a second voltage
divider resistor provided between the other end of said first
voltage divider resistor and said negative terminal of said battery
and connected in series to said Zener diode and said first voltage
divider resistor to generate an overvoltage detection signal by
conducting said Zener diode when said instantaneous value of said
battery terminal voltage exceeds said first set value and a switch
element trigger circuit to apply a switch trigger signal to said
switch elements of said output short circuit for turning them on
when said overvoltage detection circuit generates said overvoltage
detection signal.
11. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and said controller further
including deceleration state detection means to detect a
deceleration state of said internal combustion engine from a
revolution of said internal combustion engine and an opening degree
of a throttle and set value change-over means to change said second
set value to a lower value when said deceleration state detection
means detects said deceleration state of said internal combustion
engine and wherein said first switch control section comprises an
overvoltage detection circuit including a first voltage divider
resistor having one end connected to a positive terminal of said
battery, a Zener diode provided between said first voltage divider
resistor and a negative terminal of said battery with an anode
faced to said negative terminal of said battery and connected in
series to said first voltage divider resistor and a second voltage
divider resistor provided between the other end of said first
voltage divider resistor and said negative terminal of said battery
and connected in series to said Zener diode and said first voltage
divider resistor by conducting said Zener diode when said
instantaneous value of said battery terminal voltage exceeds said
first set value and a switch element trigger circuit to apply a
switch trigger signal to said switch elements of said output short
circuit for turning them on when said overvoltage detection circuit
generates said overvoltage detection signal by conducting said
overvoltage detection signal.
12. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and said controller further
including acceleration/deceleration state detection means to detect
an acceleration state of said internal combustion engine and a
deceleration thereof from a revolution of said internal combustion
engine and an opening degree of a throttle and set value
change-over means to change said second set value to a higher value
when said acceleration/deceleration state detection means detects
said acceleration state of said internal combustion engine and to
change said second set value to a lower value when said
acceleration/deceleration state detection means detects said
deceleration state of said internal combustion engine and wherein
said first switch control section comprises an overvoltage
detection circuit including a first voltage divider resistor having
one end connected to a positive terminal of said battery, a Zener
diode provided between said first voltage divider resistor and a
negative terminal of said battery with an anode faced to said
negative terminal of said battery and connected in series to said
first voltage divider resistor and a second voltage divider
resistor provided between the other end of said first voltage
divider resistor and said negative terminal of said battery and
connected in series to said Zener diode and said first voltage
divider resistor by conducting said Zener diode when said
instantaneous value of said battery terminal voltage exceeds said
first set value and a switch element trigger circuit to apply a
switch trigger signal to said switch elements of said output short
circuit for turning them on when said overvoltage detection circuit
generates said overvoltage detection signal.
13. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator while coils of said generator is
constructed to be cooled by a lubrication oil of said internal
combustion engine and said controller further including oil
temperature detection means to detect a temperature of said
lubrication oil of said internal combustion engine and set value
change-over means to change said second value to a higher value
when said temperature detected by said oil temperature detection
means exceeds a set value and wherein said first switch control
section comprises an overvoltage detection circuit including a
first voltage divider resistor having one end connected to a
positive terminal of said battery, a Zener diode provided between
said first voltage divider resistor and a negative terminal of said
battery with an anode faced to said negative terminal of said
battery and connected in series to said first voltage divider
resistor and a second voltage divider resistor provided between the
other end of said first voltage divider resistor and said negative
terminal of said battery and connected in series to said Zener
diode and said first voltage divider resistor by conducting said
Zener diode when said instantaneous value of said battery terminal
voltage exceeds said first set value and a switch element trigger
circuit to apply a switch trigger signal to said switch elements of
said output short circuit for turning them on when said overvoltage
detection circuit generates said overvoltage detection signal.
14. A battery charging apparatus as set forth in either of claims
1, 2, 7 and 8 and wherein said rectifier circuit comprises a diode
bridge type full wave rectifier circuit, said switch elements of
said output short circuit being connected between respective AC
input terminals of said rectifier circuit and a negative one of DC
output terminals thereof, said second switch control section
comprising a microcomputer to arithmetically compare said average
value of said terminal voltage detected by said average voltage
detection circuit and said second set value whereby said
microcomputer repetitively generates an on-instruction signal of
frequency sufficiently higher than an output frequency of said
generator while said average value of said terminal voltage exceeds
said second set value and a signal making an on-state of said
respective switch elements is repetitively applied to said switch
elements while said on-instruction signal is generating.
15. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and wherein said controller further
includes acceleration state detection means to detect an
acceleration state of said internal combustion engine from a
revolution of said internal combustion engine and an opening degree
of a throttle and set value change-over means to change said second
set value to a higher value when said acceleration state detection
means detects said acceleration state of said internal combustion
engine and wherein said rectifier circuit comprises a diode bridge
type full wave rectifier circuit, said switch elements of said
output short circuit being connected between respective AC input
terminals of said rectifier circuit and a negative one of DC output
terminals thereof, said second switch control section comprising a
microcomputer to arithmetically compare said average value of said
terminal voltage detected by said average voltage detection circuit
and said second set value whereby said microcomputer repetitively
generates an on-instruction signal of frequency sufficiently higher
than an output frequency of said generator while said average value
of said terminal voltage exceeds said second set value and a signal
making an on-state of said respective switch elements is
repetitively applied to said switch elements while said
on-instruction signal is generating.
16. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and said controller further
including deceleration state detection means to detect a
deceleration state of said internal combustion engine from a
revolution of said internal combustion engine and an opening degree
of a throttle and set value change-over means to change said second
set value to a lower value when said deceleration state detection
means detects said deceleration state of said internal combustion
engine and wherein said rectifier circuit comprises a diode bridge
type full wave rectifier circuit, said switch elements of said
output short circuit being connected between respective AC input
terminals of said rectifier circuit and a negative one of DC output
terminals thereof, said second switch control section comprising a
microcomputer to arithmetically compare said average value of said
terminal voltage detected by said average voltage detection circuit
and said second set value whereby said microcomputer repetitively
generates an on-instruction signal of frequency sufficiently higher
than an output frequency of said generator while said average value
of said terminal voltage exceeds said second set value and a signal
making an on-state of said respective switch elements is
repetitively applied to said switch elements while said
on-instruction signal is generating.
17. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and said controller further
including acceleration/deceleration state detection means to detect
an acceleration state of said internal combustion engine and a
deceleration thereof from a revolution of said internal combustion
engine and an opening degree of a throttle and set value
change-over means to change said second set value to a higher value
when said acceleration/deceleration state detection means detects
said acceleration state of said internal combustion engine and to
change said second set value to a lower value when said
acceleration/deceleration state detection means detects said
deceleration state of said internal combustion engine and wherein
said rectifier circuit comprises a diode bridge type full wave
rectifier circuit, said switch elements of said output short
circuit being connected between respective AC input terminals of
said rectifier circuit and a negative one of DC output terminals
thereof, said second switch control section comprising a
microcomputer to arithmetically compare said average value of said
terminal voltage detected by said average voltage detection circuit
and said second set value whereby said microcomputer repetitively
generates an on-instruction signal of frequency sufficiently higher
than an output frequency of said generator while said average value
of said terminal voltage exceeds said second set value and a signal
making an on-state of said respective switch elements is
repetitively applied to said switch elements while said
on-instruction signal is generating.
18. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator while coils of said generator are
constructed so as to be cooled by a lubrication oil of said
internal combustion engine and said controller further including
oil temperature detection means to detect a temperature of said
lubrication oil of said internal combustion engine and set value
change-over means to change said second value to a higher value
when said temperature detected by said oil temperature detection
means exceeds a set value and wherein said rectifier circuit
comprises a diode bridge type full wave rectifier circuit, said
switch elements of said output short circuit being connected
between respective AC input terminals of said rectifier circuit and
a negative one of DC output terminals thereof, said second switch
control section comprising a microcomputer to arithmetically
compare said average value of said terminal voltage detected by
said average voltage detection circuit and said second set value
whereby said microcomputer repetitively generates an on-instruction
signal of frequency sufficiently higher than an output frequency of
said generator while said average value of said terminal voltage
exceeds said second set value and a signal making an on-state of
said respective switch elements is repetitively applied to said
switch elements while said on-instruction signal is generating.
19. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and said controller further
including acceleration state detection means to detect an
acceleration state of said internal combustion engine from a
revolution of said internal combustion engine and an opening degree
of a throttle and set value change-over means to change said second
set value to a higher value when said acceleration state detection
means detects said acceleration state of said internal combustion
engine, wherein said first switch control section comprises an
overvoltage detection circuit including a first voltage divider
resistor having one end connected to a positive terminal of said
battery, a Zener diode provided between said first voltage divider
resistor and a negative terminal of said battery with an anode
faced to said negative terminal of said battery and connected in
series to said first voltage divider resistor and a second voltage
divider resistor provided between the other end of said first
voltage divider resistor and said negative terminal of said battery
and connected in series to said Zener diode and said first voltage
divider resistor to generate an overvoltage detection signal by
conducting said Zener diode when said instantaneous value of said
battery terminal voltage exceeds said first set value and a switch
element trigger circuit to apply a switch trigger signal to said
switch elements of said output short circuit for turning them on
when said overvoltage detection circuit generates said overvoltage
detection signal and wherein said rectifier circuit comprises a
diode bridge type full wave rectifier circuit, said switch elements
of said output short circuit being connected between respective AC
input terminals of said rectifier circuit and a negative one of DC
output terminals thereof, said second switch control section
comprising a microcomputer to arithmetically compare said average
value of said terminal voltage detected by said average voltage
detection circuit and said second set value whereby said
microcomputer repetitively generates an on-instruction signal of
frequency sufficiently higher than an output frequency of said
generator while said average value of said terminal voltage exceeds
said second set value and a signal making an on-state of said
respective switch elements is repetitively applied to said switch
elements while said on instruction signal is generating.
20. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and said controller further
including deceleration state detection means to detect a
deceleration state of said internal combustion engine from a
revolution of said internal combustion engine and an opening degree
of a throttle and set value change-over means to change said second
set value to a lower value when said deceleration state detection
means detects said deceleration state of said internal combustion
engine, wherein said first switch control section comprises an
overvoltage detection circuit including a first voltage divider
resistor having one end connected to a positive terminal of said
battery, a Zener diode provided between said first voltage divider
resistor and a negative terminal of said battery with an anode
faced to said negative terminal of said battery and connected in
series to said first voltage divider resistor and a second voltage
divider resistor provided between the other end of said first
voltage divider resistor and said negative terminal of said battery
and connected in series to said Zener diode and said first voltage
divider resistor by conducting said Zener diode when said
instantaneous value of said battery terminal voltage exceeds said
first set value and a switch element trigger circuit to apply a
switch trigger signal to said switch elements of said output short
circuit for turning them on when said overvoltage detection circuit
generates said overvoltage detection signal by conducting said
overvoltage detection signal and wherein said rectifier circuit
comprises a diode bridge type full wave rectifier circuit, said
switch elements of said output short circuit being connected
between respective AC input terminals of said rectifier circuit and
a negative one of DC output terminals thereof, said second switch
control section comprising a microcomputer to arithmetically
compare said average value of said terminal voltage detected by
said average voltage detection circuit and said second set value
whereby said microcomputer repetitively generates an on-instruction
signal of frequency sufficiently higher than an output frequency of
said generator while said average value of said terminal voltage
exceeds said second set value and a signal making an on-state of
said respective switch elements is repetitively applied to said
switch elements while said on instruction signal is generating.
21. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator and said controller further
including acceleration/deceleration state detection means to detect
an acceleration state of said internal combustion engine and a
deceleration thereof from a revolution of said internal combustion
engine and an opening degree of a throttle and set value
change-over means to change said second set value to a higher value
when said acceleration/deceleration state detection means detects
said acceleration state of said internal combustion engine and to
change said second set value to a lower value when said
acceleration/deceleration state detection means detects said
deceleration state of said internal combustion engine, wherein said
first switch control section comprises an overvoltage detection
circuit including a first voltage divider resistor having one end
connected to a positive terminal of said battery, a Zener diode
provided between said first voltage divider resistor and a negative
terminal of said battery with an anode faced to said negative
terminal of said battery and connected in series to said first
voltage divider resistor and a second voltage divider resistor
provided between the other end of said first voltage divider
resistor and said negative terminal of said battery and connected
in series to said Zener diode and said first voltage divider
resistor by conducting said Zener diode when said instantaneous
value of said battery terminal voltage exceeds said first set value
and a switch element trigger circuit to apply a switch trigger
signal to said switch elements of said output short circuit for
turning them on when said overvoltage detection circuit generates
said overvoltage detection signal and wherein said rectifier
circuit comprises a diode bridge type full wave rectifier circuit,
said switch elements of said output short circuit being connected
between respective AC input terminals of said rectifier circuit and
a negative one of DC output terminals thereof, said second switch
control section comprising a microcomputer to arithmetically
compare said average value of said terminal voltage detected by
said average voltage detection circuit and said second set value
whereby said microcomputer repetitively generates an on-instruction
signal of frequency sufficiently higher than an output frequency of
said generator while said average value of said terminal voltage
exceeds said second set value and a signal making an on-state of
said respective switch elements is repetitively applied to said
switch elements while said on instruction signal is generating.
22. A battery charging apparatus as set forth in claim 1 or 2 and
wherein an internal combustion engine is used as a power source for
driving said magneto generator while coils of said generator is
constructed to be cooled by a lubrication oil of said internal
combustion engine and said controller further including oil
temperature detection means to detect a temperature of said
lubrication oil of said internal combustion engine and set value
change-over means to change said second value to a higher value
when said temperature detected by said oil temperature detection
means exceeds a set value, wherein said first switch control
section comprises an overvoltage detection circuit including a
first voltage divider resistor having one end connected to a
positive terminal of said battery, a Zener diode provided between
said first voltage divider resistor and a negative terminal of said
battery with an anode faced to said negative terminal of said
battery and connected in series to said first voltage divider
resistor and a second voltage divider resistor provided between the
other end of said first voltage divider resistor and said negative
terminal of said battery and connected in series to said Zener
diode and said first voltage divider resistor by conducting said
Zener diode when said instantaneous value of said battery terminal
voltage exceeds said first set value and a switch element trigger
circuit to apply a switch trigger signal to said switch elements of
said output short circuit for turning them on when said overvoltage
detection circuit generates said overvoltage detection signal and
wherein said rectifier circuit comprises a diode bridge type full
wave rectifier circuit, said switch elements of said output short
circuit being connected between respective AC input terminals of
said rectifier circuit and a negative one of DC output terminals
thereof, said second switch control section comprising a
microcomputer to arithmetically compare said average value of said
terminal voltage detected by said average voltage detection circuit
and said second set value whereby said microcomputer repetitively
generates an on-instruction signal of frequency sufficiently higher
than an output frequency of said generator while said average value
of said terminal voltage exceeds said second set value and a signal
making an on-state of said respective switch elements is
repetitively applied to said switch elements while said on
instruction signal is generating.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] This invention pertains to a battery charging apparatus for
charging a battery by a rectified output from a magneto generator
driven by a primer such as an internal combustion engine and so
on.
BACKGROUND OF THE INVENTION
[0002] The battery charging apparatus mounted on a motor bicycle or
the like driven by an internal combustion engine comprises a
magneto generator driven by the internal combustion engine, a
rectifier circuit having input terminals connected to output
terminals of the generator and output terminals between which the
battery is connected, an output short circuit having on-off
controllable switch elements to short the output terminals of the
magneto generator when the switch elements are at an on-state and a
controller to control the switch elements of the output short
circuit in accordance with an output voltage of the battery.
[0003] An example of the prior art battery charging apparatus is
shown in FIG. 3. A magneto generator 1 generates an AC voltage by
being driven by an internal combustion engine mounted on a vehicle
such as a motor bicycle or the like. The magneto generator 1
comprises a not shown magnet rotor mounted on a crankshaft of the
internal combustion engine and a stator having three phase
generation coils Lu through Lw.
[0004] A rectifier circuit 2 to rectify an output of the generator
1 comprises a three-phase bridge circuit of diodes Du through Dw
and Dx through Dz connected to each other in a bridged manner. AC
input terminals 2u through 2w of the rectifier circuit 2 are formed
of respective connection points of the diodes Du through Dw for an
upper arm of the bridge circuit and the diodes Dx through Dz for a
lower arm of the bridge circuit while positive and negative DC
output terminals 2p and 2n of the rectifier circuit 2 are formed of
the common connection point of the cathodes of the upper arm diodes
and the common connection point of the anodes of the lower arm
diodes, respectively. The AC three-phase input terminals 2u through
2w of the rectifier circuit 2 are connected to the output terminals
1u through 1w of the generator, respectively, while the battery 3
is connected across the DC output terminals 2p and 2n of the
rectifier circuit 2.
[0005] A load 4 is connected through a power source switch 5 to
both ends of the battery 3. An overvoltage detection circuit 6
serves to detect a terminal voltage of the battery 3 to generate an
overvoltage detection signal when an instantaneous value of the
detected terminal voltage exceeds a set value.
[0006] Thyristors Thu through Thw serve as output shorting switch
elements with cathodes thereof commonly connected to the negative
output terminals of the rectifier circuit 2 and with anodes thereof
connected to the AC input terminals 2u through 2w of the rectifier
circuit 2, respectively.
[0007] In this example, an output short circuit is formed by the
diodes Dx through Dz and the thyristors Thu through Thw. When
control signals are applied to the thyristors Thu through Thw, the
thyristors having forward voltages applied across the anode and
cathode thereof among these thyristors become an on-state and the
generator is shorted between the output terminals 1u and 1v, 1v and
1w and 1w and 1u of the U, V and W phases of the generator through
the on-state thyristors and the diodes Dx through Dz.
[0008] The overvoltage detection circuit 6 comprises a voltage
divider circuit formed of a series circuit of a first divider
resistor R1, a Zener diode ZD1 and a second voltage divider circuit
R2 and connected in parallel to both sides of the battery 3 with
the cathode of the Zener diode ZD1 directed to the positive side of
the battery 3. The overvoltage detection circuit 6 conducts the
Zener diode ZD1 when the instantaneous value of the terminal
voltage of the battery 3 exceeds the set value to generate an
overvoltage detection signal.
[0009] To the connection point of the resistor R1 and the Zener
diode ZD1 of the overvoltage detection circuit 6 is connected a
base of a PNP transistor TR1 having an emitter connected to the DC
output terminals 2p of the rectifier circuit 2 while a collector of
the transistor TR1 is connected through resistors Ru through Rw to
gates of the thyristors Thu through Thw.
[0010] In this example, a switch trigger circuit 7 that applies to
the respective thyristors trigger signals for conducting the
thyristors Thu through Thw comprises the transistor TR1 and the
resistors Ru through Rw. The switch trigger circuit 7 applies the
trigger signals to the thyristors Thu through Thw when the terminal
voltage of the battery exceeds the set value and thereby the Zener
diode ZD1 is turned on to apply the trigger signals to the
thyristors Thu through Thw.
[0011] In the example of FIG. 3, a regulator circuit 8 having a
rectifying function and a voltage regulating function is
constituted by the rectifier circuit 2, the output short circuit
comprising the low arm diodes Dx through Dz of the bridge of the
rectifier circuit 2 and the thyristors Thu through Thw, the
overvoltage detection circuit 6 and the switch element trigger
circuit 7. The regulating circuit 8 and the generator 1 constitutes
the battery charging apparatus.
[0012] In the battery charging apparatus shown in FIG. 3, the DC
voltage is applied to the battery 3 from the generator 1 through
the rectifier circuit 2 to thereby charge the battery 3. The DC
voltage (the battery terminal voltage) applied from the rectifier
circuit 2 to the battery includes a ripple voltage having a
waveform corresponding to that of the AC voltage output from the
generator 1. The overvoltage detection circuit 6 applies the
trigger signals to the thyristors Thu through Thw when the
instantaneous value of the battery terminal voltage including the
ripple voltage exceeds the set value.
[0013] As the instantaneous value of the terminal voltage of the
battery 3 is equal to or less than the set value, the transistor
TR1 turns into an off-state because the Zener diode ZD1 of the
overvoltage detection circuit 6 is at a nonconductive state and
therefore the thyristors Thu through Thw are at an off-state. In
these states, the output of the generator 1 is rectified by the
rectifier circuit 2 and supplied to the battery 3 so that it is
charged. Since the power source switch 5 is closed during the
operation of the internal combustion engine, the electric power is
supplied from the battery to the load 4.
[0014] As the instantaneous value of the terminal voltage of the
battery 3 exceeds the set value, the Zener diode ZD1 gets turned on
so that the transistor TR1 becomes the on-state because of the base
current flowing through the transistor TR1 and as a result, the
trigger signals are applied from the battery 3 through the
transistor TR1 to the thyristors Thu through Thw. At that time, the
thyristors Thu through Thw are conducted while the forward voltages
are applied between the anodes and the cathodes thereof and the
output terminals of the generator 1 are shorted through either of
the conducting thyristors and the lower arm diodes Dx through Dz of
the bridge of the rectifier circuit 2. For instance, the thyristor
Thu is at the on-state while the output terminal 1u of the
generator 1 is at high potential relative to the other output
terminals 1v and 1w. At that time, the output terminals 1u and 1v
of the generator 1 are shorted through the thyristor Thu and the
diode Dy and the output terminals 1u and 1w of the generator 1 are
shorted through the thyristor Thu and the diode Dz.
[0015] In this manner, since the voltage is never applied from the
generator 1 to the rectifier circuit 2 while the output terminals
of the generator 1 are shorted, the charging current is prevented
from flowing from the rectifier circuit 2 to the battery so that
the terminal voltage of the battery is lowered. As the terminal
voltage of the battery 3 is equal to or less than the set value,
the Zener diode ZD1 becomes the nonconductive state and therefore
the transistor TR1 turns into the off-state. Thus, the trigger
signals stop being supplied to the thyristors Thu through Thw so
that the charging current is again supplied from the rectifier
circuit 2 to the battery 3. The terminal voltage of the battery 3
is maintained equal to or less than the set value by repeating this
operation.
[0016] In the aforementioned battery charging apparatus, when the
instantaneous value of the ripple voltage included in the DC
voltage applied from the rectifier circuit 2 to the battery 3
exceeds the set value, the Zener diode ZD1 becomes conductive and
the trigger signals are applied to the thyristors Thu through Thw
so that the voltage regulating operation can be made.
[0017] In this case, since the ripple voltage rises abruptly while
the revolution of the generator is high, the thyristors Thu through
Thw are triggered immediately after the ripple voltage rises and
therefore the voltage regulating operation is done at earlier
timing. On the other hand, since the ripple voltage rises slowly
while the revolution of the generator is low, the thyristors Thu
through Thw are triggered in a delayed manner and therefore the
voltage regulating operation starts at a delayed time.
[0018] Accordingly, it is required for the set value to be set at
relatively high level in order to properly control the terminal
voltage of the battery when the generator rotates at a high speed,
but this sometimes causes the battery terminal voltage to increase
when the generator rotates at low speed which delays the start of
the voltage regulating operation after the ripple voltage
rises.
[0019] On the other hand, it is required for the set value to be
set at a relatively low level in order to properly control the
terminal voltage of the battery when the generator rotates at the
low speed, but this disadvantageously prevents the battery from
being fully charged because the battery terminal voltage decreases
due to the voltage regulating operation starting too early when the
generator rotates at the high speed. Particularly, in case that an
impedance of the circuit connecting the rectifier circuit and the
battery is high, the voltage applied to the battery during the high
speed rotation decreases and therefore the battery is
insufficiently charged.
[0020] As aforementioned, since the prior art battery charging
apparatus adversely affects the voltage regulating operation during
the steady state of the generator due to the ripple voltage
included in the voltage applied from the rectifier circuit to the
battery, the circuit constant should be adjusted according to the
magnitude of the ripple voltage during the steady operation.
However, since the magnitude of the ripple voltage is determined on
the winding specification of the generator, the capacity of the
battery and the kinds of the load, the circuit constant is required
to be set in accordance with the winding specification of the
generator, the capacity of the battery and the kinds of the load.
This disadvantageously causes the design and manufacture of the
battery charging apparatus to be troublesome.
SUMMARY OF THE INVENTION
[0021] Accordingly, it is a principal object of the invention to
provide a battery charging apparatus adapted to charge a battery in
a preferable manner without being affected by the winding
specification of the generator, the capacity of the battery and the
kinds of the load.
[0022] In accordance with the present invention, there is provided
a battery charging apparatus comprising a magneto AC generator, a
rectifier circuit having input terminals connected to output
terminals of the generator, an output short circuit having on-off
controllable switch elements and shorting the output terminals of
the magneto AC generator when the switch elements are at an on
state and a controller to control the switch elements of the output
short circuit in accordance with the terminal voltage of the
battery, the controller including a first switch control section to
control the switch elements of the output short circuit to be
turned on when the instantaneous value of the terminal voltage of
the battery exceeds a first set value, an average voltage detection
circuit to detect an average value of the terminal voltage of the
battery, a second switch control section to control the switch
elements of the output short circuit so as to be turned on when the
average value of the terminal voltage of the battery exceeds a
second set value and control change-over means to change the
controls by the first control section and the second control
sections from one to the other so that the switch elements are
controlled by the second control section when an electric power is
supplied from the battery to the load and so that the switch
elements are controlled by the first control section when the load
is cut out from the battery.
[0023] With the battery charging apparatus constructed in the
aforementioned manner, since the switch elements of the output
short circuit is controlled by the second switch control section
during the steady operation in which the electric power is supplied
from the generator to the load, the voltage regulating operation is
made to short the output voltage of the magneto generator when the
average value of the battery terminal voltage reaches the second
set value.
[0024] As the load is cut out from the generator when the operation
of the generator stops, the voltage regulating operation is done by
the first switch control section in accordance with the
instantaneous value of the battery terminal voltage during the
short period until the generator stops.
[0025] As the average value of the battery terminal voltage is
detected when the generator is steadily operated and the voltage is
so adjusted that the average value thereof never exceeds the set
value, the charging voltage for the battery can be steadily
controlled without being adversely affected by the ripple voltage
having the peak value varying on the changing revolution of the
generator.
[0026] Since the ripple voltage does not affect the voltage
adjustment, the constant of the circuit is not required to be
adjusted in accordance with the winding specification of the
generator, the capacity of the battery and the kinds of the load,
which enables the battery charging apparatus to be manufactured
more easily.
[0027] Even though the impedance of the circuit connecting the
rectifier circuit and the battery is high, the appropriate range of
the voltage applied to the battery can be maintained by properly
setting the second set value when the generator is driven not only
with the low revolution, but also with the high revolution. Thus,
the battery can be prevented from being insufficiently charged.
[0028] The first switch control section is adapted to directly
detect the terminal voltage of the battery across both ends thereof
and the average voltage detection circuit serves to detect the
average value of the terminal voltage of the battery across both
ends thereof when the load is connected through the power source
switch to the battery. As the first set value is so set to be
higher than the instantaneous value of the terminal voltage of the
battery within the range over which the battery and the load are
never adversely affected when it reaches the second value, the
control by the first switch control section and the control by the
second switch control section can be automatically changed. Thus,
it will be noted that the power source switch constitutes the
control change-over means.
[0029] In this case, both of the first and second switch control
sections detect the terminal voltage of the battery while the load
is connected to the battery, but since the first set value is so
set to be higher than the instantaneous value of the battery
terminal voltage when the average value of the battery terminal
voltage reaches the second value. Thus, it will be noted that while
the load is connected to the battery, the average value of the
terminal voltage detected by the average voltage detection circuit
exceeds the second value so that the second switch control section
turns on the switch elements of the output short circuit before the
first switch control section turns on the switch elements of the
output short circuit. In this manner, the second switch control
section controls the switch elements of the output short circuit on
the steady operation of the generator whereby the voltage
adjustment operation is made so that the average value of the
battery terminal voltage can be maintained equal to or less than
the second set value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The above and other objects and features of the invention
will be apparent from the detailed description of the preferred
embodiments of the invention, which are described and illustrated
with reference to the accompanying drawings, in which;
[0031] FIG. 1 is a schematic diagram of a battery charging
apparatus constructed in accordance with an embodiment of the
invention;
[0032] FIG. 2 is a schematic diagram of a modified second switch
control section for the battery charging apparatus of FIG. 1;
and
[0033] FIG. 3 is a schematic diagram of a prior art battery
charging apparatus.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0034] Referring now to FIG. 1, there is shown a battery charging
apparatus constructed in accordance with one embodiment of the
invention. A magneto AC generator 1 is driven by an internal
combustion engine mounted on a vehicle such as a motor bicycle or
the like so as to generate a three-phase AC voltage. A rectifier
circuit 2 has three-phase AC input terminals 2u through 2w
connected to output terminals 1u through 1w of the generator to
rectify an output of the generator. A battery 3 is connected
between DC output terminals 2p and 2n of the rectifier circuit 2 to
be charged through the rectifier circuit 2 by the output of the
generator 1. A load 4 may be connected through a power source
switch 5 to both ends of the battery 3. A negative terminal of the
battery is grounded to earth. The power source switch 5 may
comprise a conventional key switch that is closed when the internal
combustion engine is to be driven and opened when the internal
combustion engine stops.
[0035] The generator 1 comprises a magnet rotor mounted on a
crankshaft of the internal combustion engine and a stator having
three-phase generation coils Lu through Lw wound on an armature
core. The generator may be displaced within a cover mounted on a
crankcase of the engine so that lubrication oil for the engine may
be sprayed against and cool the generation coils Lu through Lw.
[0036] The rectifier circuit 2 may be identical to that shown in
FIG. 3 and comprises the diodes Du through Dw and Dx through Dz.
The thyristors Thu through Thw as output shorting switch elements
have anodes connected to the AC input terminals 2u through 2w and
cathodes commonly connected to the negative output terminal of the
rectifier circuit 2. The thyristors Thu though Thw are connected in
reverse parallel to the diodes Dx through Dz for the upper arm of
the rectifier circuit 2. The output short circuit is constituted by
these thyristors Thu through Thw and the diodes Dx through Dz in a
manner similar to that of FIG. 3. In the output short circuit, when
a control signal is applied to the thyristors Thu through Thw, the
thyristor having a forward voltage applied across the anodes and
the cathodes thereof are turned on. When either of the thyristors
Thu through Thw is turned on, the output terminals 1u and 1v, 1v
and 1w or 1w and 1u among the three-phase U, V and W output
terminals of the generator 1 are shorted through the on-state
thyristors and the diodes Dx through Dz.
[0037] An overvoltage detection circuit 6 may comprise a first
voltage divider resistors R1 having one end connected to a positive
terminal of the battery 3, a Zener diode ZD1 having an anode
connected in series to the first voltage divider resistor R1 while
being provided between the first voltage divider resistor R1 and
the negative terminal of the battery 3 with the anode faced to the
negative terminal of the battery 3 and a second voltage divider
resistor R2 connected in series to the Zener diode ZD1 and the
first voltage divider resistor R1 while being provided between the
other end of the first voltage divider resistor R1 and the negative
terminal of the battery 3.
[0038] A switch element trigger circuit 7 serves to apply trigger
signals to the thyristors Thu through Thw when the overvoltage
detection circuit 6 generates an overvoltage detection signal and
may comprises a PNP transistor TR1 having a base connected to a
connection point of the first resistor R1 and the Zener diode ZD1
and an emitter connected to the positive DC output terminal 2p of
the rectifier circuit 2 and resistors Ru though Rw connected
between a collector of the transistor TR1 and gates of the
thyristors Thu through Thw.
[0039] In the embodiment of FIG. 1, a first switch control section
10 may be formed of the overvoltage detection circuit 6 and the
switch trigger circuit 7 and serves to control the switch elements
Thu through Thw of the output short circuit to be turned on when
the instantaneous value of the terminal voltage of the battery 3
exceeds the first set value. The first switch control section and
the output short circuit constitute a load disconnection
overvoltage protection circuit 10. This load disconnection
overvoltage protection circuit and the rectifier circuit 2
constitute a regulator circuit 8.
[0040] One end of a resistor R3 is connected to one end of the load
4 connected through the power source switch 5 to the positive
terminal of the battery 3 and a resistor R4 is connected between
the other end of the resistor R3 and the negative terminal of the
battery 3. A smoothing capacitor C1 is connected to both ends of
the resistor R4 and a voltage across the capacitor C1 is input to
an analog-digital (A/D) converter 11. The resistors R3 and R4, the
capacitor C1 and the A/D converter 11 constitute an average voltage
detection circuit 12 to detect the average value of the terminal
voltage of the battery 3.
[0041] An output of the A/D converter 11 is input to a CPU 13 of a
microcomputer. To an output port of the CPU 13 is connected a base
of a transistor TR2 having an emitter connected to the negative
terminal of the battery and a collector connected to the base of
the transistor TR1.
[0042] In the embodiment of FIG. 1, the microcomputer having the
CPU 13 and the transistor TR2 constitute a second switch control
section 14 that controls the switch elements of the output short
circuit so as to be turned on when the average value of the battery
3 detected by the average voltage detection circuit 12 exceeds the
second set value. The second switch control section 14 and the
average voltage detection circuit 12 constitute a steady operation
battery charging apparatus 15.
[0043] The CPU 13 arithmetically compares the average value of the
terminal voltage of the battery detected by the average voltage
detection circuit 12 with the second set value to repetitively
generate an on-instruction signal having a frequency sufficiently
higher than output frequency of the generator when the average
value of the battery terminal voltage exceeds the second set value.
The on-instruction signal is applied to the base of the transistor
TR2. As the on-instruction signal is applied, the transistor TR2 is
turned on and therefore the transistor TR1 is also turned on. Thus,
the trigger signal is applied to the switch elements Thu through
Thw of the output short circuit.
[0044] In the battery charging apparatus of FIG. 1, the first set
value providing a voltage adjusting value of the first switch
control section is so set to be higher than the instantaneous value
of the battery terminal voltage when the average value of the
battery terminal voltage reaches the second set value within a
range over which the battery 3 and the load 4 are not adversely
affected.
[0045] Accordingly, in the condition that the power source switch 5
is closed, as the average value of the terminal voltage of the
battery 3 exceeds the second value, the CPU 13 supplies the base
current to the transistor TR2 so that it is turned on. Thus, the
transistor TR1 is also turned on and the trigger signal is applied
to the thyristors Thu through Thw so that they are turned on. In
this manner, the output terminals of the generator are shorted so
that the terminal voltage of the battery 3 is lowered. As the
terminal voltage of the battery 3 gets equal to or less than the
second set value, the base current no longer flows from the CPU 14
to the transistor TR2. Thus, the transistor TR2 is turned off and
therefore the trigger signal stops being supplied to the thyristors
Thu through Thw. Thus, the charging current again flows from the
rectifier circuit 2 to the battery 3. This operation is repeated
and as a result the average value of the terminal voltage of the
battery 3 is kept adjacent to the second set value.
[0046] As the power source switch (or the key switch) 5 is opened
in order to stop the internal combustion engine, the load 4 is
disconnected from the battery 3. The internal combustion engine is
rotating for a while even after the switch 5 is opened. At that
time, as the terminal voltage of the battery 3 exceeds the first
set value, the Zener diode ZD1 is conducted and therefore the
transistor TR1 is turned on. This causes the thyristors Thu through
Thw to be conducted so that the output terminals of the generator 1
are shorted and the terminal voltage of the battery is lowered.
[0047] In the embodiment of FIG. 1, the second switch control
section is provided with the microcomputer, which is used for
changing the second value in accordance with various control
conditions so that the battery charging apparatus has various
additional functions, which will be described later.
[0048] As aforementioned, in many cases, the magneto AC generator
is driven by the internal combustion engine as a drive power
source. As the generation coils are shorted on the voltage
adjustment, the generator generates much brake torque, which causes
the generator to be much load to the internal combustion engine.
Thus, as the voltage adjustment operation is made when the internal
combustion engine is accelerating, the engine will possibly have
poor acceleration characteristics.
[0049] In order to avoid such a problem, there may be provided
acceleration condition detection means including a throttle sensor
to detect an opening degree of a throttle valve and a revolution
sensor to provide the revolution information such as the rotary
angle information of the engine and the rotation speed information
of the engine to detect that the internal combustion engine is
accelerating from the rotation speed of the internal combustion
engine and the opening degree of the throttle by inputting the
outputs of the sensors to the CPU 13 and practicing the
predetermined program stored in ROM of the CPU 13 and set value
change-over means to change the second set value to a larger value
when the acceleration condition detection means detects that the
internal combustion engine is in the acceleration condition. The
acceleration condition detection means and the set value
change-over means may be preferably a component element of the
controller for the battery charging apparatus.
[0050] In this manner, as the second set value is changed to the
larger value when the internal combustion engine is in the
acceleration condition, little operation of the voltage adjustment
on the acceleration of the engine can be made and therefore the
generator can be prevented from applying much load to the internal
combustion engine. This enables improved acceleration
characteristics of the engine.
[0051] In case that the internal combustion engine is used for the
drive power source of the generator, there may be provided
deceleration condition detection means to detect that the internal
combustion engine is decelerating from the rotation speed of the
internal combustion engine and the opening degree of the throttle
by practicing the predetermined program in the CPU 13 and set value
change-over means to change the second set value to a smaller value
when the deceleration condition detection means detects that the
internal combustion engine is in the deceleration condition. In the
same manner, the deceleration condition detection means and the set
value change-over means may be also preferably a component element
of the controller of the battery charging apparatus.
[0052] In this manner, as the second set value is changed to the
smaller value when the internal combustion engine is in the
deceleration condition, the generator is kept in the condition of
being shorted on the deceleration of the engine so that the
generator can generate much brake torque. This enables to improve
deceleration characteristics of the engine.
[0053] In order to improve both of the acceleration characteristics
and the deceleration characteristics of the engine, there can be
provided acceleration/deceleration condition detection means to
detect that the internal combustion engine is accelerating or
decelerating from the rotation speed of the internal combustion
engine and the opening degree of the throttle by practicing the
predetermined program in the CPU 13 and set value change-over means
to change the second set value to the larger value when the
acceleration/deceleration condition detection means detects that
the internal combustion engine is in the acceleration condition and
to change the second set value to the smaller value when the
acceleration/deceleration condition detection means detects that
the internal combustion engine is in the deceleration condition.
The acceleration/deceleration condition detection means and the set
value change-over means may be preferably a component element of
the controller of the battery charging apparatus.
[0054] In some cases, the battery charging apparatus may be formed
so that the generation coils are cooled by the lubrication oil for
the internal combustion engine as in the aforementioned embodiment.
In this case, there may be provided an oil temperature sensor or
oil temperature detection means to detect a temperature of the
lubrication oil for the internal combustion engine and set value
change-over means to change the set value to a larger value when
the temperature of the oil detected by the oil temperature
detection means exceeds the set value can be practiced by the CPU
13 for a further component element of the controller.
[0055] In this manner, as the second set value is changed to the
larger value when the oil temperature exceeds the set value, the
voltage adjustment operation will be made with lower frequency and
therefore heat from the generation coils will be generated in lower
degree. Thus, the temperature of the generation coils can be
lowered.
[0056] In general, when the battery is charged at low atmospheric
temperature, the battery is charged with poor charging
characteristics. Thus, the voltage applied to the battery is
required to get higher in order to properly charge the battery.
Therefore, when the atmospheric temperature is low, the set value
providing an upper limit of the battery terminal voltage is
desirably higher.
[0057] In this case, a temperature sensor may be provided which
detects an atmospheric temperature at which the battery is charged
and set value arithmetical operation means may be practiced by the
CPU 13 to arithmetically operate the second value providing a limit
value for the average value of the battery terminal voltage
relative to the atmospheric temperature of the battery. The second
switch control section is preferably constructed so as to turn on
the switch elements of the output short circuit when the average
value of the terminal voltage detected by the average voltage
detection circuit exceeds the second set value obtained by being
arithmetically operated in accordance with the atmospheric
temperature. The set value arithmetical operation means may be
constructed so that the second set value is a larger value at the
lower atmospheric temperature while it is a smaller value as the
atmospheric temperature increases.
[0058] In this invention, the first switch control section 10
serves to prevent the overvoltage from being applied across the
battery 3 while the generator 1 is cut from the load 4 so as to
stop the operation thereof. In the battery charging apparatus to
which the invention is applied, it will be considered that the
first switch control section may be omitted and only then second
switch control section may be provided to adjust the charging
voltage in accordance with the average value of the battery
terminal voltage. In this case, the average voltage detection
circuit is required to be connected to both ends of the battery in
order to protect the battery from the overvoltage when the
generator is cut from the load and stops the operation thereof.
[0059] However, with the apparatus constructed in this manner, the
battery will be possibly discharged through the average voltage
detection circuit that is always connected to both ends of the
battery when the generator stops the operation thereof. The first
switch control section is required to be provided in order to avoid
this.
[0060] As apparent from the foregoing, the first switch control
section 10 is required to have such a construction as can prevent
the battery from being discharged when the generator stops the
operation.
[0061] In the embodiment shown in FIG. 1, the overvoltage detection
circuit 6 may comprise the first voltage divider resistor R1 having
the one end connected to the positive terminal of the battery, the
Zener diode ZD1 connected in series to the first voltage divider
resistor R1 with the anode faced to the negative terminal of the
battery between the first voltage divider resistor and the battery
and the second voltage divider resistor R2 connected in series to
the Zener diode and the first voltage divider between the other end
of the first voltage divider resistor and the negative terminal of
the battery so as to generate the overvoltage detection signal by
conducting the Zener diode when the instantaneous value of the
terminal voltage of the battery exceeds the first set value. Thus,
it will be noted that the use of the overvoltage detection circuit
can prevent the battery from being discharged in the condition that
the generator stops the operation.
[0062] In case that the diode bridge type full-wave rectifier
circuit as shown in FIG. 1 is used for rectifying the output of the
magneto AC generator, the switch elements of the output short
circuit are used between the respective AC input terminals of the
rectifier circuit and the negative DC output terminal thereof. Even
in case that the generator is constructed so as to generate a
single phase AC output, at least two switch elements of the output
short circuit should be provided because the rectifier circuit has
the two AC input terminals.
[0063] There has no problem in case that the peak values of two
half waves of the AC output generated by the generator are equal to
each other, but if the peak values thereof sequentially appearing
from the generator are possibly different from each other, the
switch element shorting the half wave having the higher peak value
is turned on prior to the other switch elements. This causes the
particular switch element to be used more frequently and therefore
the life span of the switch element will be disadvantageously
shorter.
[0064] In order to avoid the disadvantages, all the switch elements
of the output short circuit are preferably turned on when the
average value of the battery terminal voltage exceeds the second
set value in spite of the difference between the peak values of the
half waves of the AC output from the generator.
[0065] In the aforementioned embodiment, the second switch control
section 14 is provided with the microcomputer that makes a
comparatively arithmetical operation of the average value of the
battery terminal voltage detected by the average voltage detection
circuit and the second set value to repetitively generate from the
microcomputer the on-instruction signal of frequency (clock
frequency of the microcomputer) sufficiently higher than the
frequency of the generator output. While the on-instruction signal
is generating, the signals for turning on the switch elements of
the output short circuit are repetitively applied to the respective
switch elements.
[0066] In this manner, even though the peak values of the half
waves of the AC output from the generator are different from each
other or the three phase outputs of FIG. 1 are unbalanced, all the
switch elements are turned on when the average value of the battery
terminal voltage exceeds the second set value and therefore the
life span of the particular switch elements can be prevented from
being shortened.
[0067] In case that the set value arithmetical operation means or
the set value change-over means are provided that changes the
second set value in accordance with the various conditions, the
upper limit of the set value is properly determined within the
range over which the battery and the load are not adversely
affected. The first set value is set so as to get higher than the
instantaneous value of the battery terminal voltage when the
average value of the battery terminal voltage reaches the maximum
value of the second set value.
[0068] In case that there may be a plurality of means to change the
second set value in accordance with the control conditions, the
conditions to determine the second set value have priority order
given. When the condition for increasing the second set value and
the condition for decreasing the second set value are overlapped,
the condition having the higher priority order is selected. For
example, when the engine is detected to be at the deceleration
state in the condition where the temperature of the lubrication oil
increases, the second set value is changed to a higher value in
order to protect the generation coil with priority.
[0069] Although, in the aforementioned embodiment, the second
switch control section is provided with the CPU that arithmetically
compares the average value of the battery terminal voltage with the
second set value, a comparator may be alternatively provided in the
second switch control section that serves to compare the average
value of the battery terminal voltage with the second set value.
For instance, as shown in FIG. 2, a comparator CP1 having an output
step of open collector type may be provided in place of the CPU 13
of the circuit of FIG. 1. The comparator CP1 has a non-inversion
input terminal and an inversion terminal to which a voltage across
a capacitor C1 (corresponding to the average value of the battery
terminal voltage) and a reference voltage Vr providing the second
set value are input, respectively and an output terminal connected
to a base of a transistor TR2 and also connected through a resistor
R5 to the positive terminal of the battery 3.
[0070] With the apparatus constructed as shown in FIG. 2, the
potential of the output terminal of the comparator CP1 is
substantially equal to the grounded potential when the average
value of the battery terminal voltage is equal to or less than the
second set value and therefore the transistor TR2 has no base
current flowing through the base thereof. Thus, since the
transistor TR1 is kept at the off-state, no trigger signal is
applied to the thyristors Thu though Thw. As the average value of
the battery terminal voltage exceeds the second set value, the
output terminal of the comparator CP1 is released from the grounded
earth and therefore the base of the transistor TR2 has the base
current flowing through the resistor R5. This turns on the
transistor TR1 and the trigger signal is applied to the thyristors
Thu through Thw.
[0071] Although, in the embodiment of FIG. 1, the invention may be
applied to the generator constructed to generate the three-phase AC
output, it may be also applied to the magneto generator that is
constructed to generate the single phase AC output.
[0072] Also in the illustrated embodiment, although the invention
is applied to the apparatus having the full-wave rectifier circuit
used for rectifying the AC output of the generator, it may be
applied to the apparatus having a half wave rectifier circuit
used.
[0073] Although, in the illustrated embodiment, the power source
switch 5 serves as the control change-over means to change the
controls of the first and second switch control sections so that
the switch elements Thu through Thw are controlled by the second
switch control section 14 when the electric power is supplied from
the battery 3 to the load by the power source switch 5 while they
are controlled by the first switch control section 10 when the load
4 is cut from the battery 3, it should be noted that the control
change-over means is never limited thereto. For instance, in FIG.
1, the average voltage detection circuit 12 may be disposed between
the battery 3 and the power source switch 5 and the control
changing switch forming the control change-over means may be
provided in series to the resistors R3 and R4 of the detection
circuit 12 so that the control changing switch is turned on when
the load current is detected while the control changing switch is
turned off when the load current is not detected whereby the
controls by the first and second switch control sections may be
changed in accordance with the presence of the load current.
[0074] According to the invention, since the average value of the
battery terminal voltage is detected when the magneto AC generator
is steadily operated and the charging voltage is adjusted not so as
to exceed the average set value, the battery charging voltage can
be advantageously controlled without being affected by such a
ripple voltage as has the peak value changed in accordance with
variation in the revolution of the generator. Also, since the
voltage adjustment is never affected by the ripple voltage, the
constant of the circuit is never adjusted in accordance with the
specification of the generator, the capacity of the battery, the
kind of the load and so on, the battery charging apparatus can be
more easily manufactured.
[0075] Furthermore, according to the invention, with the second set
value properly set, even though the circuit impedance between the
rectifier circuit and the battery is high, the voltage adjustment
is never affected by the variation in the rising portion of the
ripple voltage and therefore the charging voltage can be kept
within the appropriate range not only at the low speed rotation of
the generator, but also at the high speed rotation thereof. Thus,
it will be noted that the battery has no shortage of charge.
[0076] Although some preferred embodiments of the invention have
been described and illustrated with reference to the accompanying
drawings, it will be understood by those skilled in the art that
the are by way of example, and that various changes and
modifications may be made without departing from the spirit and
scope of the invention, which is defined only to the appended
claims.
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