U.S. patent application number 09/726925 was filed with the patent office on 2001-06-07 for battery charging device.
Invention is credited to Najima, Kazuki.
Application Number | 20010002786 09/726925 |
Document ID | / |
Family ID | 18353265 |
Filed Date | 2001-06-07 |
United States Patent
Application |
20010002786 |
Kind Code |
A1 |
Najima, Kazuki |
June 7, 2001 |
Battery charging device
Abstract
A battery charging device includes a power supply coupler and a
power receiver coupler. The power supply coupler includes a primary
coil, a communication unit to communicate the power receiver
coupler, a thermistor for detecting the temperature of the power
supply coupler, and a communication interruption circuit for
interrupting a communication signal when the predetermined value is
detected by the thermistor. When the temperature of the power
supply coupler exceeds the predetermined value, a signal is
produced by the communication interruption circuit to prevent an
excessive temperature rise in the power supply coupler. The signal
may, for example, stop the supply of electric power to the power
supply couple.
Inventors: |
Najima, Kazuki; (Kariya-shi,
JP) |
Correspondence
Address: |
Kurt E. Richter
Morgan & Finnegan, L.L.P.
345 Park Avenue
New York
NY
10154
US
|
Family ID: |
18353265 |
Appl. No.: |
09/726925 |
Filed: |
November 30, 2000 |
Current U.S.
Class: |
320/108 |
Current CPC
Class: |
Y02T 90/12 20130101;
H02J 7/0042 20130101; Y02T 10/70 20130101; B60L 53/305 20190201;
Y02T 10/7072 20130101; B60L 3/04 20130101; Y02T 90/14 20130101;
B60L 2250/10 20130101; H02J 50/80 20160201; B60L 2240/547 20130101;
H02J 7/00034 20200101; H02J 7/025 20130101; Y02T 90/16 20130101;
B60L 53/126 20190201; B60L 2240/36 20130101; B60L 53/122 20190201;
B60L 53/34 20190201; B60L 2240/545 20130101; H02J 50/10
20160201 |
Class at
Publication: |
320/108 |
International
Class: |
H02J 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 1, 1999 |
JP |
11-342377 |
Claims
What is claimed is:
1. A battery charging device comprising: a power supply coupler
having the following components: a first core, a primary coil
located around the first core, and a case enclosing the first core
and the primary coil; a power receiver coupler including a second
core for forming a magnetic path with said first core, a secondary
coil located around the second core, and a case enclosing the
second core and the secondary coil; a power supply device connected
to the primary coil; a battery connected to the secondary coil,
wherein the battery is charged by an inductive current generated in
the secondary coil when electric power is supplied to the primary
core by the power supply device; and a temperature detector for
detecting the temperature of the power supply coupler and for
generating an electric signal for use in preventing the temperature
of the components from exceeding a predetermined level.
2. A battery charging deice according to claim 1, wherein the power
supply device includes a control unit for controlling the level of
the electric power supplied to the primary coil, wherein the power
supply coupler includes a communication unit for transmitting a
signal, which carries information that the control unit uses to
control the electric power, to the control unit, and a
communication interruption circuit to interrupt the signal when the
temperature detector indicates that the power supply coupler has
reached the predetermined level.
3. A battery charging device according to claim 2, wherein the
communication interruption circuit includes a temperature switch,
which is turned off when the temperature of the power supply
coupler exceeds the predetermined level.
4. A battery charging device according to claim 2, wherein the
communication interruption circuit outputs a first signal to the
control unit when the temperature of the power supply coupler is
below the predetermined level and a second signal, which is
different from the first signal, when the temperature of the power
supply coupler exceeds the predetermined level.
5. A battery charging device according to claim 1, wherein the
temperature detector is connected to the control unit, and wherein
the power supply device includes a control unit for controlling the
electric power supplied to the primary coil in response to the
first and second signals generated by the temperature detector.
6. A battery charging device comprising: a power supply coupler
having the following components: a first core, a primary coil
located around the first core, and a case the first core and the
primary coil; a power receiver coupler including a second core for
forming a magnetic path with the first core, a secondary coil
located around the first core, and a case enclosing the second core
and the secondary coil; a power supply device for supplying an
electric power to the primary coil; a battery connected to the
secondary coil, wherein the battery is charged by an inductive
current generated in the secondary coil when electric power is
supplied to the secondary coil from the power supply device; a
first communicating unit in the power receiver coupler for
transmitting a first electric signal, which carries information
related to the condition of the battery, to the power supply
coupler; a second communication unit in the power supply coupler,
wherein the second communication unit responds to the first
electric signal by transmitting the first electric signal as a
second electric signal to the power supply device; a temperature
detector located in the power supply coupler for generating a third
electric signal, wherein the third electric signal indicates
whether a temperature in the power supply coupler has reached a
predetermined value; a communication interruption circuit connected
to the temperature detector to receive the third electric signal,
wherein the third electric signal interrupts the second electric
signal when the temperature exceeds the predetermined value; and a
control unit in the power supply unit for controlling the electric
power supplied to the primary coil in response to the second
electric signal.
7. A battery charging device according to claim 6, wherein the
communication interruption circuit includes a temperature switch,
which is turned off when the temperature of the power supply
coupler exceeds the predetermined temperature value.
8. A battery charging device according to claim 6, wherein the
first communication unit, the second communication unit and the
control unit communicate with each other with a digital signal, and
wherein the communication interruption circuit continues to
transmit the second electric signal to the control unit if the
second electric signal is supplied to the control unit by the
second communication unit when the temperature of the power supply
coupler is below the predetermined value, and the communication
interruption circuit continuously outputs a Low level signal to the
control unit if the second electric signal is not supplied to the
control unit from the second communication unit, and when the third
electric signal indicates that temperature exceeds the
predetermined value, the second communication unit continues to
output a Hi level signal to the control unit, and the control unit
interrupts the supply of electric power to the primary coil in
response to the Hi level signal.
9. A battery charging device according to claim 6, wherein the
first communication unit, the second communication unit and the
control unit communicates with each other via a digital signal, and
wherein the communication interruption circuit continues to output
the second signal to the control unit when the second control
signal is transmitted to the control unit from the second
communication unit, and the communication interruption circuit
continuously outputs the Hi level signal to the control unit when
the second electric signal is not transmitted to the control unit
from the second communication unit, and when the third electric
signal indicates that the temperature exceeds the predetermined
value, the second communication unit continues to the Hi level
signal and the control unit interrupts the supply of electric power
to the primary coil.
10. A power supply coupler for the battery charging device having a
temperature detector for detecting the temperature of the inside of
the power supply coupler and for generating an electric signal when
the temperature of the inside of the power supply coupler exceeds a
predetermined level.
11. A power supply coupler for a battery charging device, the power
supply coupler being connected to a power supply device, which has
a control unit for controlling a supply of electric power to the
power supply coupler, wherein the battery charging device has a
power receiver coupler that includes a first core and a secondary
coil located around the first core, the power supply coupler
comprising: a second core that forms a magnetic path with the first
core when the power supply coupler is inserted into the power
receiver coupler; a primary core located around the second core and
connected to the power supply device to receive the electric power;
a temperature detector for detecting a temperature of said power
supply coupler and for producing an output signal when the
temperature exceeds a predetermined value, which causes the control
unit to stop the supply of electric power for preventing an
excessive temperature rise beyond the predetermined value in the
power supply coupler; and a case enclosing the second core, the
primary core and the temperature detection means.
12. A power supply coupler according to claim 11, wherein the power
supply coupler further comprises a communication unit for
transmitting an electric signal, which caries information used by
the control unit, to the control unit, and a communication
interruption circuit for interrupting the electric signal when the
predetermined temperature value is detected by the temperature
detector.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to battery charging device and, more
particularly, to an electromagnetic induction, non-contact type
battery charging device suited for charging batteries of a
self-propelled apparatus such as electric vehicles.
[0002] In conventional battery charging devices, there are two
types of charging systems, namely, conductive charging device and
an inductive charging device. The inductive charging device is also
called an electromagnetic, non-contact type battery charging
device. The inductive charging device is advantageous in that it
cannot be hindered by a bad electrical contact unlike the
conductive charging device. Further, with the use of the inductive
charging device, vehicles are not required to carry large battery
charging equipment, and the size of the battery charging device can
be reduced.
[0003] Charging of the battery is usually achieved by inserting a
power supply coupler connected to a power supply device with a
cable into a power receiver coupler mounted within the electric
vehicle. When the couplers are coupled to one another, the couplers
transmit or receive information necessary for setting charging
conditions by means of respective internal communication units.
[0004] In the prior art battery charging device discussed above,
the charging of the battery is done at high frequency and at high
rates, there is a great deal of heat buildup in the power supply
charging coupler. In order to prevent the power supply coupler from
being damaged due to thermal shock, it is a usual practice to have
the power receiver coupler equipped with a cooling unit of an air
type or a water type. The power receiver coupler is also equipped
with a temperature sensor, which serves to monitor the operating
temperature of the power receiver coupler during charging and to
transmit a temperature signal related to the detected temperature
to a control unit of the power supply device via the communication
unit of the power supply coupler. When the battery charger
overheats, the control unit of the power supply device serves to
stop the charging of the battery in response to the temperature
signal delivered from the temperature sensor.
[0005] However, even when such thermal protection is carried out,
if there is a failure in the communication system, it is difficult
to prevent a decrease in cooling performance or an abnormal
operating condition of the power supply coupler.
[0006] In the prior art battery charging device as discussed above,
the cooling performance and overheating is usually detected by a
detector incorporated in the power receiver coupler. For this
reason, if the temperature of the power supply coupler is excessive
and the temperature of the power receiver coupler is not excessive,
charging of the battery continues. As the charging of the battery
continues, the temperature of the power supply coupler further
increases, which may cause unstable operation of the communication
units and cause difficulties in achieving a stable charging of the
battery. In addition, the power supply coupler is subject to
thermal distortion and various component parts incorporated in the
power supply coupler are subject to thermal cracking.
SUMMARY OF THE INVENTION
[0007] It is therefore an object of the present invention to
provide a battery charging device which is highly reliable.
[0008] In order to meet the above and other objects, the present
invention provides a battery charging device.
[0009] The battery charging device has a power supply coupler
connected to a power supply device, and a power receiver coupler
into which the power supply coupler is adapted to be inserted for
charging a battery of an electric vehicle. The power supply coupler
has components, which include a first core, a primary coil located
around the first core and supplied with electric power from the
power supply device, and a case accommodating the first core and
the primary coil. The power receiver coupler includes a second core
that forms a magnetic path with the first core when the power
supply coupler is coupled to the power receiver coupler, a
secondary coil located around the second core, and a case
accommodating the second core and the secondary coil. The power
supply device is connected to the primary coil. The battery is
connected to the secondary coil and is charged with an electric
current generated in the secondary coil when the electric power is
supplied to the primary coil. The power supply coupler includes a
temperature detector for detecting the temperature of the power
supply coupler to generate an electrical signal that is used to
avoid avoiding an excessive temperature in the components of the
power supply coupler.
[0010] The present invention further provides a battery charging
device. The battery charging device has a power supply coupler
including a first core, a primary coil located around the first
core and connected to receive electric power from a power supply
device, and a case accommodating the first core and the primary
coil. The power receiver coupler includes a second core that forms
a magnetic path with the first core of the power supply coupler
when it is coupled to the power receiver coupler, a secondary coil
located around the second core, and a case accommodating the second
core and the secondary coil. The power supply device supplies an
electric current to the primary coil. The battery is connected to
the secondary coil and is charged with an electric current
generated in the second coil when the electric power is supplied to
the primary coil. The power receiver coupler includes a first
communication unit for transmitting a first electric signal, which
includes information related to the charging state of the battery,
to the power supply coupler. The power supply coupler includes a
second communication unit for receiving the first electric signal
and transmitting the same as a second electric signal to the power
supply device; temperature detector for generating a third electric
signal indicating the temperature of the power supply coupler; and
a communication interruption circuit connected to the temperature
detector for receiving the third electric signal. The communication
interruption circuit interrupts when the third electric signal
exceeds a predetermined value. The power supply device includes a
control unit for controlling the electric power supplied to the
primary coil on the basis of the second electric signal.
[0011] The present invention also provides a power supply coupler
for a battery charging device which is connected to a power supply
device having a control unit and which has a power receiver coupler
mounted in an electric vehicle for a battery located in the
vehicle. The power receiver coupler has a core and a secondary coil
located around the core and connected to the battery.
[0012] The power supply coupler has a core and a primary coil
located around the core. The core of the power supply device forms
a magnetic path with the core of the power receiver coupler. The
primary coil induces an electric current in the secondary coil when
an electric power is supplied to the primary coil. The power supply
coupler also has a temperature detector, which detects the
temperature of the power supply coupler to generate an electric
signal when the temperature of the power supply coupler exceeds a
predetermined value. The power supply device has a control unit
responsive to the electric signal for controlling the electric
power to be supplied to the primary coil.
[0013] Other aspects and advantages of the invention will become
more apparent from the following description, taken in conjunction
with the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention, together with objects and advantages thereof,
may best be understood by reference to the following description of
the presently preferred embodiments together with the accompanying
drawings, in which:
[0015] FIG. 1 is a schematic view illustrating the whole structure
of a battery charging device according to the present
invention;
[0016] FIG. 2 is a cross sectional view of a power supply coupler
and a power receiver coupler taken on line 2-2 of FIG. 1;
[0017] FIG. 3 is a front view of the power supply coupler having a
casing, a portion of which is omitted;
[0018] FIG. 4 is a transverse cross sectional view of a cable taken
on line 4-4 of FIG. 3;
[0019] FIG. 5 is a circuit diagram of a preferred embodiment of a
communication interruption circuit incorporated in the power supply
coupler of the battery charger according to the present
invention;
[0020] FIG. 6 is a view illustrating various signals used in the
communication unit of the power supply coupler and the
communication interruption circuit;
[0021] FIG. 7 is a circuit diagram of another preferred embodiment
of communication interruption circuit;
[0022] FIG. 8 is a circuit diagram of another preferred embodiment
of a communication interruption circuit;
[0023] FIG. 9 is a circuit diagram of still another preferred
embodiment of a communication interruption circuit;
[0024] FIG. 10 is a circuit diagram of still another embodiment of
a communication interruption circuit;
[0025] FIG. 11 is a circuit diagram of a further preferred
embodiment of a communication interruption circuit;
[0026] FIG. 12 is a circuit diagram of one preferred example of a
temperature detector incorporated in the power supply coupler of
the battery charging device according to the present invention;
and
[0027] FIG. 13 is a circuit diagram of another preferred embodiment
of a temperature detector.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] A preferred embodiment of a battery charging device
according to the present invention will now be described below in
detail with reference to the drawings as applied to an electric
vehicle.
[0029] In FIG. 1, the electric vehicle is assigned with a reference
numeral 600. The electric vehicle 600 has an electric motor (not
shown) and a battery E connected to the electric motor (not shown).
The electric motor serves as a prime mover powered by the battery E
and constitutes an essential part of a drive system of the electric
vehicle 600.
[0030] The battery charging device includes a power supply device
400, a power supply coupler 200 and a power receiver coupler 300.
The power supply device 400 is normally located at a battery
charging service station. The power supply coupler 200 is connected
to the power supply device 400 by a cable 500. The power receiver
coupler 300 and its associated parts are incorporated in the
electric vehicle 600. In this instance, the power receiver coupler
300 is mounted at a front part of the vehicle 600.
[0031] Charging of the battery E is achieved by inserting the power
supply coupler 200 into the power receiver coupler 300. If the
power supply coupler 200 is coupled to the power receiver coupler
300, the power supply device 400 supplies an electric power to the
power supply coupler 200. Consequently, the power receiver coupler
300 receives electric power from the power supply coupler 200 to
charge the battery E.
[0032] As clearly shown in FIG. 3, the power supply coupler 200
comprises a case 10. The case 10 includes an inserter portion 52,
which fits into the power receiver coupler 300, and a handle or
grip portion 53, which is gripped by a worker at the battery
charging service station. The inserter portion 52 has a paddle
shape which is designed to be inserted into or to be removed from
the power receiver coupler 300. Further, the inserter portion 52
has front and rear portions which are configured to have the same
shape to permit the insertion of the power supply coupler 200 into
the power receiver coupler 300 in either of two orientations. The
grip portion 53 has a plate-like shape in which an aperture 53a is
formed to allow gripping by the worker.
[0033] The inserter portion 52 is hollow. The distal end portion of
the inserter portion 52 has a first cylindrical core 11 made of
ferrite material and a primary coil 12 wound around the first core
11.
[0034] As clearly shown in FIG. 2, the power receiver coupler 300
has a case 27. The case 27 has a hollow body 42, the rear and
bottom sides of which are opened, and a cover plate 43, which is
fixed to the rear side of the hollow body 42 by fasteners such as
screws. The hollow body 42 has an upper wall 44, in which a coupler
inserter port 45 is formed, and a side wall, in which a plurality
of apertures 27b are formed to permit outside air to enter. Also,
the lower end of the case 27 has a motor fan. The motor fan
includes a motor 28, a fan 29, which driven by the motor 28, and a
housing 47, which envelopes the motor 28 and the fan 29. The
housing 47 has upper and bottom walls, in which an opening and a
plurality of small bores 27d are formed, respectively. The motor
fan is secured to an upper wall of the housing 47, which is fixed
to a lower end of the case 27 by fasteners such as screws to align
the opening 27a with a lower opening of the casing 27. The power
receiver coupler 300 is fixed at the front part of the electric
vehicle 600 such that the coupler inserter port 45 faces
upward.
[0035] The lower portion of the case 27 has a second core, which
includes a first core member 30 and a second core member 31, both
of which are made of ferrite material. The first core member 30 is
designed to have a substantially E-shaped configuration, a
cylindrical center magnetic pole 30a, and a magnet pole at each
side of the center magnetic pole. The second core member 31 is
designed to have a substantially plate-like configuration. The
second core member 31 is attached to the first core member 30 such
that it spans the magnetic poles of the second core member 31 and
forms a magnetic path. A secondary coil 32 is located around the
second core 30 and is formed circuit boards formed into a one piece
coil board. The coil board has a center bore, which receives the
center magnetic pole 30a of the first core member 30, and is
located in the body 42 between the first and second core members 30
and 31 and is fixed in place by a support pedestal 27c of the case
27.
[0036] The upper portion of the case 27 houses a guide plate 33 and
an auxiliary member 34. The guide plate 33 is located between the
coil board forming the secondary coil 32 and the case 10 of the
power supply coupler 200 and is fixed to the case 27. The auxiliary
member 34 is located between the cover plate 43 and the case 10 of
the power supply coupler 200 and has an opening that faces the
cover plate 43. Also, the wall defining the opening is fixed to the
cover plate 43 by fasteners such as screws.
[0037] The guide plate 33 has an inner surface that faces the case
10 of the power supply coupler 200, and a plurality of projections
are formed on the inner surface. Likewise, the auxiliary member 34
has an inner surface that faces the case 10 of the power supply
coupler 200, and a plurality of projections 34a are formed on the
inner surface. The projections 34a are elongated and extended along
a longitudinal axis of the power supply coupler 200. The
projections 34a are parallel to each other and lie on a plane
perpendicular to the plane of the sheet of FIG. 2. The guide plate
33 has the same kind of projections. The protrusions 34a support
the case 10 of the power supply coupler 200 and guide the power
supply coupler 200 when it is inserted into the power receiver
coupler 300.
[0038] The power receiver coupler 300 includes a communication unit
17, which has a communication circuit 35 and a light
emitter-receiver element 48. The communication circuit 35 and the
light emitter-light receiver element 48 are mounted on a circuit
board 36. The circuit board 36 is fixed within the auxiliary member
34. The light emitter-light receiver element 48 has a light emitter
section 48a for emitting infrared light, and a light receiver
section 48b for receiving infrared light.
[0039] The power supply coupler 200 also includes a communication
unit 13. As shown in FIGS. 2 and 3, the communication unit 13
includes a communication circuit 15, and a light emitter-light
receiver element 16. The communication unit 15 and the light
emitter-light receiver element 16 are mounted on a circuit board
14, which is located in the inserting portion 52 of the case 10 at
a position close to an edge of the aperture 53a and is fixed to the
case 10. The light emitter-light receiver element 16 includes a
light emitter section 16a for emitting infrared light and a light
receiver section 16b for receiving infrared light. A reflector 18
is mounted on the circuit board 14.
[0040] The light emitter-light receiver elements 16 and 48 and the
reflector 18 are located in the case 10 such that the infrared
light emitted from the light emitter section 48a of the light
emitter-light receiver element 48 enters the light receiver section
16b of the light emitter-light receiver element 16 via the
reflector 18, and the infrared light emitted from the light emitter
section 16a of the light emitter-light receiver element 16 enters
the light receiver section 48b of the light emitter-light receiver
element 48. The reflector 18 is mounted on the circuit board 14 to
direct the infrared light emitted from the light emitter section
48a precisely to the light receiver section 16b in either of the
two possible orientations of the power supply coupler 200. In other
words, the power supply coupler 200 can be reversed in the power
supply coupler 200, and the infrared light will be properly
transmitted and received. To transmit the infrared light, the
auxiliary member 34 is made of an electrical insulation material
that transmits infrared light. The case 10 also has portions made
of the same electrical insulation material at locations adjacent to
the reflector 18 to transmit the infrared light.
[0041] The communication unit 15 is connected to the light
emitter-light receiver element 16 and the control unit 19 of the
power supply device 400. The communication circuit 35 of the power
receiver coupler 300 is connected to the light emitter-light
receiver element 48 and the sensor located at the battery E. The
communication circuit 35 produces an information signal indicating
the battery voltage and the temperature of a battery liquid or
electrolyte, in response to signals from the battery sensor. As
already noted above, the information signal is transmitted through
the light emitter-light receiver element 48, the reflector 18 and
the light emitter-light receiver element 16 to the communication
circuit 15, which delivers the information signal to the control
unit 19 of the power supply device.
[0042] FIG. 4 shows a cross sectional view of the cable 500 which
connects the power supply coupler 200 to the power supply device
400. The cable 500 includes a power supply wire 20, a ground wire
21, a transmission wire TX, a receiver wire RX, and four power
wires 22. The power wires 22 contact each other. The power wires 22
are connected between the primary coil 12 of the power supply
coupler 200 and the power supply device 400 and supply electric
power to the primary coil 12. The transmission wire TX, the
receiver wire RX, the power wire 20 and the ground wire 21 are
connected between the control unit 19 and the communication unit
13. The transmission wire TX transmits the information signal,
which represents the various information discussed above, to the
communication unit 13. The receiver wire RX transmits the
information transmitted from the communication unit 17 to the
control unit 19 via the communication unit 13. As shown in FIG. 3,
the wires 20, 21, TX and RX are led from the cable 500 within the
power supply coupler 200 and are connected to the communication
unit 13 via connectors of the circuit board 14.
[0043] As seen in FIG. 1, charging of the battery E is started at
the charging service station by the worker by inserting the power
supply coupler 200 into the power receiver coupler 300.
[0044] As seen in FIG. 2, when the power supply coupler 200 is
inserted into the power receiver coupler 300, the first core 11 of
the power supply coupler 200 is brought into axial alignment with
the center magnetic pole 30a of the power receiver coupler, the
first and second cores are magnetically coupled to each other, and
the primary and secondary coils are electrically coupled in a
non-contact condition. During the coupling step, an alternating
current is supplied to the primary coil 12 of the power supply
coupler 200 via the power wire 22 of the cable 500. In this
instance, an electric current is generated in the secondary coil 32
of the power receiver coupler 300 due to electromagnetic induction.
This current is converted into a D.C. current and delivered to the
battery E of the electric vehicle 600 for charging.
[0045] During battery charging, the communication unit 35 of the
power receiver coupler 300 generates a first digital signal which
indicates, for example, the output voltage of the battery E and the
temperature of the battery liquid in response to the output signal
delivered from the battery sensor of the battery E. The light
emitter-light receiver element 48 produces an infrared signal from
the light emitter section 48a in response to the first digital
signal. The infrared signal is transmitted through the reflector 18
of the power supply coupler 200 to the light receiver section 16a
and the infrared signal is converted to the information signal,
which is supplied to the communication circuit 15. The
communication circuit 15 produces a second digital signal, which is
supplied to the control unit 19 of the power supply device 400,
through the transmission wire TX of the cable 500 in response to
the information signal. The control unit 19 includes a
microprocessor, which determines the magnitude of the alternating
current to be supplied to the primary coil 12 of the power supply
coupler 200 in accordance with the second digital signal, which
carries the information from the communication unit 17 indicating
the battery voltage and the temperature of the battery liquid. The
microprocessor also serves to monitor the above information during
the battery charging and supplies the electric power to the primary
coil 12.
[0046] During the battery charging, there is a great deal of heat
buildup in the primary and secondary coils 12 and 32. However, the
coils 12 and 32 are cooled by an air stream flowing through the
case 27. When the power supply coupler 200 is coupled to the power
receiver coupler 300, the fan 29 shown in FIG. 2 starts to rotate,
which draws outside air to the inside of the case 27 through the
apertures 27b. The air flows through the recesses formed between
the projections of the guide plate 33 and the projections 34a of
the auxiliary member 34 and is forced out from the case 27 by the
fan 29. The primary coil 12 and the second core formed by the core
members 30 and 31 are cooled by the air stream flowing through the
case 27. Further, the secondary coil 32 of the power supply coupler
300, the first core 11 and the case 10 are also cooled by the air
stream.
[0047] If the temperature of the power supply coupler 200 increases
beyond a given level due to drop in the power of the fan 29 or some
other failure, the battery charging device of the present invention
stops the supply of electric power to the primary coil 12 of the
power supply coupler 200, which prevents overheating of the power
supply coupler 200 and the power receiver coupler 300.
[0048] In order to achieve this, a temperature detector 23, which
includes, for example, a thermistor, is mounted on the circuit
board 14 as shown in FIG. 3. A communication interruption circuit
24 is also mounted on the circuit board 14. The communication
interruption circuit 24 input and output terminals connected to the
communication circuit 15 and the control unit 19, respectively.
[0049] The thermistor 23 is a positive characteristic type
thermistor, in which its resistance increases with an increase in
temperature. The communication interruption circuit 24 is
responsive to a temperature signal delivered from the thermistor
23. If the temperature signal exceeds a predetermined level, the
interruption circuit 24 interrupts the communication signal
supplied to the control unit 19 from the communication unit 13. The
predetermined temperature is set to a value to prevent the
overheating of the power supply coupler 200. More specifically,
this temperature has is chosen to prevent the thermal distortion of
the case 10 of the power supply coupler 200 or thermal damage to
the various component parts incorporated in the power supply
coupler 200.
[0050] As shown in FIG. 5, the communication interruption circuit
24 includes a N-channel MOSFET 25, a NPN type transistor 26, and a
resistor R. The gate G of the MOSFET 25 is connected to the
communication circuit 15, the source S is connected to ground, and
the drain D is connected to the control unit 19 of the power supply
device 400 via the transmission wire TX. The collector of the
transistor 26 is connected between the gate of the MOSFET 25 and
the communication circuit 15, the emitter is connected to the
ground, and the base is connected to ground via the thermistor 23
and is also connected to a power source V via a resistor R.
[0051] In the battery charging device according to the present
invention, the communication circuit 15 is designed to continuously
produce a Hi signal when the communication of the signals is
interrupted. The output of the MOSFET 25 is Low when the gate G
receives an ON signal and is Hi when the gate G receives an OFF
signal.
[0052] During battery charging, the communication circuit 35 of the
power receiver coupler 300 produces the first digital signal, which
is applied through-light emitter and light receiver element 48 and
the light emitter-light receiver element 16 to the communication
circuit 15. The communication circuit 15 transmits the second
digital signal to the control unit 19 of the power supply device
400. The second digital signal includes a pulse signal indicated by
the uppermost waveform in FIG. 6.
[0053] During the battery charging, the temperature of the power
supply coupler 200 is continuously detected by the thermistor 23.
The electrical resistance of the thermistor 23 increases when the
temperature of the inside of the power supply coupler 200
increases. More specifically, the electrical resistance of the
thermistor 23 increases as the temperature of the air surrounding
the thermistor 23 increases.
[0054] If the resistance of the thermistor 23 is below a given
value, which represents the predetermined temperature, the base
potential of the transistor 26 is maintained at a level that turns
on the transistor 26. For this reason, the MOSFET 25 generates an
output signal corresponding to the second digital signal, which is
delivered from the communication circuit 15. The output signal of
the MOSFET 25 is sent to the control unit 19. Therefore, the
transistor 26 does not affect the output signal transmitted to the
control unit 19 via the communication unit 13 from the
communication unit 17.
[0055] If the battery information signal is not transmitted from
the communication circuit 35 through the communication circuit 15,
the transistor 26 is held in its off state, and the MOSFET 25 is
held in its on state. Then, the output of the communication unit 24
is low as shown by the lowermost waveform in FIG. 6.
[0056] If the resistance of the thermistor 23 exceeds the given
level, the base potential of the transistor 26 increases, and the
transistor 26 is turned on. When this occurs, the output signal of
the communication circuit 15 is caused to flow to the emitter of
the transistor 26. Therefore, the gate G of the MOSFET 25 goes to a
low level (The MOSFET 25 is turned off). Under these circumstances,
the outputs of the MOSFET 25 or the communication circuit 24 goes
to high level regardless of the presence or the absence of the
signal from the communication circuit 15, as shown by a middle
waveform in FIG. 6. This condition continues until the resistance
of the thermistor 23 decreases to a value to turn on the MOSFET
26.
[0057] The control unit 19 responds to a low level output of the
communication interruption circuit 24 supplying electric power to
the primary coil 12 of the power supply charging coupler 200
according to the information indicating the battery condition
transmitted from the communication unit 17 via the communication
unit 13. If, on the contrary, the communication circuit 24
continues to produce a high level output, namely, when the
temperature of the power supply coupler 200 exceeds the
predetermined temperature, the control unit 19 stops the supply of
electric power to the primary coil 12.
[0058] The battery charging device according to the present
invention has the following advantages.
[0059] (1) The casing 10 enclosing the primary coil 12 of the power
supply charging coupler 200 is internally provided with the
temperature detector 23 for detecting an increase in the
temperature of the power supply charging coupler 200 beyond the
predetermined level. The temperature detector 23 detects whether
the temperature of the power supply coupler 200 exceeds or is below
the predetermined level. It is possible to take a step such as
stopping the charging of the battery, on the basis of the result of
the temperature detector 23 to prevent an excessive temperature
increase in the power supply charging coupler 200. As a result,
overheating of the power supply coupler 200 is prevented, and
thermal distortion or thermal damage to the components of the power
supply coupler 200 is effectively and reliably prevented.
[0060] (2) When the temperature detector 23 detects that the
temperature of the power supply coupler 200 exceeds the
predetermined level and produces an output signal to that effect,
the communication interruption circuit 24 interrupts the
information signal for battery charging control from being supplied
to the control unit 19 from the communication circuit 15. With the
provision of the communication interruption circuit 24, the number
of communication wires between the communication interruption
circuit 24 and the power supply coupler 200 and between the power
supply coupler 200 and the control unit 19 of the power supply
device 400 is minimized.
[0061] (3) The communication unit 13 continues to produce the Hi
level output signal when the communication is interrupted, and the
communication interruption circuit 24 provides a Hi level output
signal when the temperature of the power supply coupler 200 exceeds
the predetermined level. For this reason, the control unit 19 can
easily discriminate between a failure in the communication system
and an abnormal temperature increase, thus it is possible to take a
step such as to stopping the supply of the electric power to the
power supply coupler 200 or a step of continuing to supply electric
power upon modification of various charging conditions. For
example, if communication is interrupted just before the completion
of charging, further continuous charging of the battery may be
deemed safe and charging may be continued.
[0062] (4) The power supply charging coupler of the battery charger
of the electric vehicle is frequently subjected to vibrations,
acceleration and heat. Since, however, overheating of and damage to
the power supply coupler 200 is reliably prevented, the battery
charging device is very reliable.
[0063] It should be apparent to those skilled in the art that the
present invention may be embodied in may other specific forms
without departing from the spirit or scope of the invention.
Particularly, it should be understood that the invention may be
embodied in the following forms.
[0064] While, in the battery charging device of the preferred
embodiment discussed above, the communication interruption circuit
24 has been described as having the MOSFET 25 that provides a Hi
level output signal when the resistance value of the thermistor 23
exceeds a value corresponding to the predetermined temperature, it
may be modified such that the MOSFET 25 produce a Low level output
signal when the resistance of the thermistor 23 exceeds a value
corresponding to the predetermined temperature.
[0065] FIG. 7 shows an example of a communication interruption
circuit 24 employing such a MOSFET. In FIG. 7, the communication
interruption circuit 24 includes a transistor 37, which is a NPN
type, and its collector is connected to a junction between the
MOSFET 25 and the communication circuit 15, its emitter is
connected to the power supply V, and its base connected to ground
via the resistor R and to the power supply V via the thermistor
23.
[0066] In the communication interruption circuit 24 discussed
above, if the resistance of the thermistor 23 is below a value
corresponding to the predetermined temperature, the transistor 37
is maintained in its off state. If, on the contrary, the resistance
of the thermistor 23 exceeds a value corresponding to the
predetermined temperature, the transistor 37 is turned on. When the
transistor 37 is turned on, the output of the transistor 37 goes to
the Hi level regardless of the output signal being produced by the
communication circuit 15. Therefore, the MOSFET 25 is turned on and
produces a low level output signal. The control unit 19 responds to
the Low level output signal (the communication signal) by stopping
the charging of the battery. Since, in this instance, the MOSFET 25
produces a Low level signal when the communication circuit 15 is
stopped and when temperature in the power supply charging coupler
is excessive, it is difficult for the control unit 19 to make a
judgment, but this embodiment has the advantages (1), (2) and
(4).
[0067] Further, another modification is made in which, when the
communication circuit 15 stops communication, the communication
circuit 15 continuously produces a Low level signal, which enables
the MOSFET 25 to be omitted.
[0068] FIG. 8 shows a preferred example of such a communication
interruption circuit 24. In the communication interruption circuit
24 of FIG. 8, the MOSFET 25 shown in FIG. 7 is omitted. When
communication is stopped, the communication circuit 15 produces a
Low level signal. If, in this instance, the resistance of the
thermistor 23 exceeds a value representing the predetermined
temperature, the transistor 37 is turned on and the communication
interruption circuit 24 continues to produce a Hi level signal
regardless of the output signal produced by the communication
circuit 15. For this reason, the control unit 19 has the advantages
(1), (2) and (4) and has the advantage that a failure in the
communication system and an excessive temperature can be easily
discriminated.
[0069] Further, the temperature detector may include not only a
positive charaterizing thermistor 23 but also a negative
characteristic thermistor. This is achieved by modifying the
communication interruption circuit 24 of FIG. 5 in such that the
base of the transistor 26 is connected to ground through the
resistor R and is also connected to the power supply via the
thermistor 23. Also in the communication interruption circuit 24
shown in FIGS. 7 and 8, the base of the transistor 37 is connected
to the ground via the thermistor 23 and is connected to the power
source V via the resistor R. In this case, the advantages are
similar to those of the first embodiment.
[0070] In addition, the communication interruption circuit 24 may
be modified as shown in FIG. 9 to enable detection of an excessive
rise in the temperature of the power supply charging coupler
without increasing the number of communication wires for
interrupting the signal being transmitted to the control unit 19
from the communication circuit 15.
[0071] In such a communication interruption circuit 24, only a
temperature switch 38 is connected as the temperature detector
between the control unit 19 and the communication circuit 15. The
temperature switch 38 may, for example, include a bimetal arranged
to actuate when the temperature of the power supply coupler 200
exceeds the predetermined value, that is, when the temperature of
the power supply coupler 200 increases to an excessive level. In
this instance, the control unit 19 is designed to stop the supply
of the electric power to the power supply coupler 200 when the
output of the communication circuit 15 is off for a given time
interval.
[0072] Further, the communication interruption circuit 24 may be
modified as shown in FIG. 10. In this modification, the resistor R
is connected between the control unit 19 and the communication
circuit 15, and a junction between a resistor Rand the
communication circuit 15 is connected to the power source V via the
temperature switch 39. The temperature switch 39 is turned on when
temperature of the power supply coupler 200 reaches the above noted
predetermined value. If the temperature of the power supply coupler
200 reaches an excessive level, the temperature switch 39 is turned
on and the output signal of the communication interruption circuit
24 is held at the Hi level. It is possible for the control unit 19
to easily discriminate between a communication failure and an
excessive temperature rise by arranging the communication circuit
15 to produce a low level output signal when communication is
stopped by the communication circuit 15.
[0073] Furthermore, the communication interruption circuit 24 may
be modified as shown in FIG. 11, in which a resistor R is connected
between the control unit 19 and the communication circuit 15, and
the temperature switch 39 is connected between a junction between
the control unit 19 and the resistor R and ground. In this case,
the temperature switch 39 is of the type which is turned on when
the temperature switch 39 reaches the predetermined
temperature.
[0074] In this embodiment, if the temperature of the power supply
coupler 200 reaches an excessive temperature, the temperature
switch 39 is turned on, and the output of the transmission
interruption circuit 24 goes to a Low level. Accordingly, it is
possible for the control unit 19 to easily discriminate between a
communication failure and an excessive temperature rise by
arranging the communication circuit 15 to produce a Hi level output
signal when communication is stopped by the communication circuit
15.
[0075] In the communication interruption circuits 24 shown in FIGS.
9 to 11, the MOSFET 25 and transistors 26 and 37 are omitted. These
circuits are simpler in structure than those of FIGS. 5, 7 and
8.
[0076] In the communication interruption circuits that produce a
signal enabling discrimination between a communication failure and
an excessive temperature rise, the power supply device 400 may be
modified to have an alarm device, such as a lamp or a buzzer, that
is driven in response to an excessive temperature rise in the power
supply charging coupler 200. With this modification, it is possible
to call a person's attention in the battery charging service
station when an excessive temperature rise takes place in the power
supply coupler 200.
[0077] Also, when the temperature detection means 23 detects that
the temperature of the power supply coupler 200 exceeds the
predetermined level, the detection data may be directly supplied to
the control unit 19. FIG. 12 shows a circuit diagram designed to
achieve this. The temperature detector 23 includes a temperature
sensor 40, which is directly connected to the control unit 19 of
the power supply device. The control unit 19 monitors the
variations in the resistance of the temperature sensor 40 to stop
the supply of the electric power to the primary coil when the
detected temperature data exceeds the given level. In this case, it
is easy for the control unit 19 to judge whether or not the
temperature of the power supply coupler has reached the
predetermined level.
[0078] To directly receive the temperature detection signal, the
control unit 19 may be connected to another temperature detector
23, which is shown in FIG. 13. In this modification, the
temperature detector 23 includes a thermistor 40 and a comparator
41. The positive terminal of the comparator 41 is connected to a
source of a reference voltage to receive a reference voltage
signal, and the negative terminal is connected to the thermistor 40
to receive a temperature detection signal. The comparator 41
compares the temperature detection signal and the reference voltage
signal to produce an output signal, which is sent to the control
unit 19.
[0079] In the temperature detector 23 of FIG. 13, the comparator 41
generates a Hi level signal when the temperature of the power
supply coupler 200 exceeds the predetermined level. The comparator
41 generates a Low level signal when the temperature of the power
supply coupler 200 is below the predetermined level. These output
signals are supplied to the control unit 19, which can easily judge
whether there has been an excessive temperature rise in the power
supply coupler 200. In this embodiment, a single additional signal
wire is required to supply the output signals to the control unit
19.
[0080] In addition, the power supply device 400 may include a
diagnosis device, which separately stores the data indicating a
communication failure and an excessive temperature rise. This
arrangement makes it easy for a worker, who is in charge of repair
or inspection to easily clear up the cause of the failure or the
malfunction.
[0081] In the preferred embodiments discussed above, although the
power supply coupler 200 and the power receiver coupler 300 employ
communication units using infrared communication, these
communication units may be replaced with other types of wireless
communication units.
[0082] In the preferred embodiments discussed above, also, although
only the power supply coupler 200 has been shown and described as
having the temperature detector 23, the power receiver coupler 300
may also have the same temperature detector. With this arrangement,
both of the temperature detectors prevent the power supply coupler
and the power receiver coupler from overheating and permit reliable
temperature management and control during the charging of the
battery.
[0083] In the preferred embodiments discussed above, furthermore,
although the battery charging device has been shown and described
as being applied to electric vehicles, it may be also applied to
other self-propelled apparatus such as a self-propelled robot
powered by a battery.
* * * * *