U.S. patent application number 15/434418 was filed with the patent office on 2017-06-08 for measurement system.
This patent application is currently assigned to MAKITA CORPORATION. The applicant listed for this patent is MAKITA CORPORATION. Invention is credited to Masaaki FUKUMOTO, Masafumi NODA, Hitoshi SUZUKI, Takuya UMEMURA.
Application Number | 20170160346 15/434418 |
Document ID | / |
Family ID | 48782243 |
Filed Date | 2017-06-08 |
United States Patent
Application |
20170160346 |
Kind Code |
A1 |
NODA; Masafumi ; et
al. |
June 8, 2017 |
MEASUREMENT SYSTEM
Abstract
A measurement system according to one aspect of the present
invention includes a battery pack and at least one type of
connected device to which the pack is connected. The pack includes
a first detection device detecting a predetermined physical
quantity in the pack and having a predetermined measurement range.
The connected device includes a second detection device detecting a
physical quantity the same as the predetermined physical quantity
and having a measurement range different from the range of the
first detection device. One of the pack and the connected device
includes a receiving device and a measurement processing device
that performs a predetermined measurement process by using one of:
a detection-value-related information received by the receiving
device; and a detection result by one device of the first detection
device and the second detection device, the one device being
provided in one of the pack and the connected device.
Inventors: |
NODA; Masafumi; (Anjo-shi,
JP) ; SUZUKI; Hitoshi; (Anjo-shi, JP) ;
FUKUMOTO; Masaaki; (Anjo-shi, JP) ; UMEMURA;
Takuya; (Anjo-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAKITA CORPORATION |
Anjo-shi |
|
JP |
|
|
Assignee: |
MAKITA CORPORATION
Anjo-shi
JP
|
Family ID: |
48782243 |
Appl. No.: |
15/434418 |
Filed: |
February 16, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13939485 |
Jul 11, 2013 |
9606188 |
|
|
15434418 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 10/4257 20130101;
H02J 7/00034 20200101; H02J 7/00047 20200101; G01R 31/3648
20130101; Y02E 60/10 20130101; G01R 31/382 20190101; H02J 7/0021
20130101; H02J 7/00036 20200101 |
International
Class: |
G01R 31/36 20060101
G01R031/36; H02J 7/00 20060101 H02J007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 12, 2012 |
JP |
2012-156592 |
Claims
1. A measurement system comprising: a battery pack containing a
battery; and at least one type of connected device to which the
battery pack is to be connected, wherein the battery pack comprises
a first detection device that is configured to detect a
predetermined physical quantity in the battery pack and that has a
predetermined measurement range, wherein the at least one type of
connected device comprises a second detection device that is
configured to detect a physical quantity and that has a measurement
range different from the measurement range of the first detection
device, wherein the physical quantity is the same as the
predetermined physical quantity, wherein one of the battery pack
and the at least one type of connected device is a first device,
and the other of the battery pack and the at least one type of
connected device is a second device, the first device comprising: a
receiving device configured to receive a detection-value-related
information that is transmitted from the second device and that
directly or indirectly indicates a detection result by one of the
first detection device and the second detection device; and a
measurement processing device configured to (i) perform a
predetermined measurement process by using the
detection-value-related information received by the receiving
device in a case where the receiving device receives the
detection-value-related information and (ii) to ignore the
detection-value-related information failed to be received by the
receiving device not to thereby perform the measurement process in
a case where the receiving device fails to receive the
detection-value-related information, the measurement process
comprising calculation of a remaining battery capacity of the
battery, and the one device being provided in the first device, and
wherein the second device comprises a transmission device
configured to transmit the detection-value-related information to
the first device.
2. The measurement system according to claim 1, wherein the at
least one type of connected device comprises a battery charger that
is configured to charge the battery.
3. A measurement system comprising: a battery pack containing a
battery; and a battery charger to which the battery pack is to be
connected, wherein the battery pack comprises a first detection
device that is configured to detect a predetermined physical
quantity in the battery pack and that has a predetermined
measurement range, wherein the battery charger comprises: a second
detection device that is configured to detect a physical quantity
and that has a measurement range different from the measurement
range of the first detection device, the physical quantity being
the same as the predetermined physical quantity; and a transmission
device configured to transmit a detection-value-related information
to the first device, the detection-value-related information
directly or indirectly indicating a detection result by the second
detection device, and wherein the battery pack comprises: a
receiving device configured to receive the detection-value-related
information transmitted from the battery charger; and a measurement
processing device configured to (i) perform a predetermined
measurement process by using the detection-value-related
information received by the receiving device in a case where the
receiving device receives the detection-value-related information
and (ii) to ignore the detection-value-related information failed
to be received by the receiving device not to thereby perform the
measurement process in a case where the receiving device fails to
receive the detection-value-related information, the measurement
process comprising calculation of a remaining battery capacity of
the battery.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a Continuation of application Ser. No. 13/939,485
filed Jul. 11, 2013, which claims the benefit of Japanese Patent
Application No. 2012-156592 filed on Jul. 12, 2012 in the Japan
Patent Office. The disclosure of the prior applications is hereby
incorporated by reference herein in its entirety.
BACKGROUND
[0002] The present invention relates to a measurement system that
measures a physical quantity in a battery pack.
[0003] There has been a known battery pack that contains a
rechargeable battery and includes a function of calculating a
remaining battery capacity of the rechargeable battery. The
remaining battery capacity calculated by the battery pack can be
used for various purposes; for example, in an electric power tool
to which this battery pack is attached and which is operated by
electric power from the rechargeable battery, the calculated
remaining battery capacity is used to display the remaining battery
capacity of the rechargeable battery in a simplified manner.
[0004] There have been known various methods of calculating a
remaining battery capacity of a rechargeable battery. For example,
Unexamined Japanese Patent Application Publication No. 2010-164322
discloses the following technique: a value of a discharge current
is detected by an electric current detection unit provided inside
assembled cells; the detected value is successively integrated so
as to calculate a value of a discharge capacity; the value of the
discharge capacity is deducted from a value of a capacity in a
fully-charged state, thereby calculating a value of the remaining
battery capacity.
[0005] Moreover, Japanese Patent No. 3225119 discloses the
following technique: in a battery pack, an electric-current
detection resistor that detects a value of a charge current and a
value of a discharge current from a rechargeable battery is
provided; both of a time-integrated value of the detected value of
the charge current and a time-integrated value of the detected
value of the discharge current are added or deducted, thereby
calculating a value of the remaining battery capacity. By taking
into account both of the discharge and charge in the
above-described manner, the remaining battery capacity can be more
accurately calculated.
SUMMARY
[0006] However, in a battery pack for an electric power tool, there
may be a case where a value of a charge current is, for example,
around 10 A at a maximum, while a value of a discharge current
exceeds, for example, 100 A at a maximum, and therefore, the value
of the charge current is greatly different from the value of the
discharge current. For this reason, if it is intended to detect
both of the value of the charge current and the value of the
discharge current by the same single electric-current detection
unit provided inside the battery pack, this electric-current
detection unit essentially needs to be configured to be capable of
measuring an electric current value up to around 100 A. Therefore,
as the electric current value becomes lower, an error of the
detection becomes greater. Consequently, it is difficult to
accurately calculate the remaining battery capacity.
[0007] Even when focusing only on the discharge current, the value
of the discharge current may be high, for example, exceed 100 A, or
may be low, for example, 10 A or below, and dependent on an
operation state of the electric power tool. Thus, a fluctuation
range of the value of the discharge current is greater. Therefore,
as the value of the discharge current during operation is lower, an
accuracy of the detection becomes low, causing a greater detection
error. As a result, it becomes difficult to accurately calculate
the remaining battery capacity.
[0008] The aforementioned problem in calculating the remaining
battery capacity in the battery pack is one example, and the same
problem as the aforementioned problem may occur when other
detection objects (physical quantities) are detected by a detection
device. Specifically, it is necessary to configure such that, as a
range of a physical quantity as a detection object is greater, the
detection device is capable of detecting a value up to a maximum
value within the range. Thus, the lower a detection value is, the
lower the detection accuracy becomes.
[0009] As above, in one aspect of the present invention, it is
preferable that a physical quantity can be detected with high
accuracy by using a simple configuration, regardless of a range of
the physical quantity as a detection object.
[0010] One aspect of the present invention is a measurement system
provided with a battery pack containing a battery, and at least one
type of connected device to which the battery pack is to be
connected. The battery pack includes a first detection device that
is configured to detect a predetermined physical quantity in the
battery pack and that has a predetermined measurement range. The at
least one type of connected device includes a second detection
device that is configured to detect a physical quantity and that
has a measurement range different from the measurement range of the
first detection device, the physical quantity being the same as the
predetermined physical quantity. One of the battery pack and the at
least one type of connected device is a first device, and the other
of the battery pack and the at least one type of connected device
is a second device. The first device includes a receiving device
and a measurement processing device. The receiving device is
configured to receive a detection-value-related information that is
transmitted from the second device and that directly or indirectly
indicates a detection result by one of the first detection device
and the second detection device. The measurement processing device
is configured to perform a predetermined measurement process by
using one of: the detection-value-related information received by
the receiving device; and a detection result by one device of the
first detection device and the second detection device, the one
device being provided in the first device. The second device
includes a transmission device configured to transmit the
detection-value-related information to the first device. Here, the
measurement range means a maximum value of a physical quantity in a
measurement range (detection range) that can be normally detected
by the first detection device and the second detection device.
[0011] In the above-constituted measurement system of the present
invention, the battery pack and the at least one type of connected
device are provided with the respective detection devices for
detection of the same physical quantity. Although these detection
devices detect the same physical quantity as a detection object,
the detection devices have different respective measurement ranges
from each other. Therefore, if the physical quantity is great, this
physical quantity can be accurately detected by the detection
device having the higher measurement range. On the other hand, if
the physical quantity is small, this physical quantity can be
accurately detected by the detection device having the lower
measurement range.
[0012] Moreover, to the measurement processing device, the
detection result by the detection device in the first device
provided with this measurement processing device is transmitted. In
addition, the detection result (detection-value-related
information) by the detection device in the second device is
transmitted to the measurement processing device from the second
device. Thereby, the measurement processing device can easily
obtain both of the detection results by the detection devices
having the different measurement ranges.
[0013] Thus, the measurement system of the present invention makes
it possible to highly-accurately detect a physical quantity as a
detection object by a simple configuration, regardless of a range
of the physical quantity.
[0014] The first detection device and the second detection device
may detect any physical quantity as a detection object. For
example, the first detection device and the second detection device
may be configured to detect an electric current to be discharged
from the battery or to be charged to the battery, as the physical
quantity.
[0015] In this case, the electric current is detected by the
different measurement ranges, respectively, of the first detection
device and the second detection device. Accordingly, by performing
the measurement process with the detection result of each of the
detection devices, it is possible to perform the measurement
process with high accuracy.
[0016] If the physical quantity as the detection object is an
electric current, the first detection device may be configured to
detect a value of the electric current in a predetermined first
measurement range, and the second detection device may be
configured to detect a value of the electric current in a
predetermined second measurement range lower than the first
measurement range.
[0017] In the measurement system configured as above, in a case of
an electric current having a relatively large value, the detection
result by the first detection device is adopted, while in a case of
an electric current having a relatively small value, the detection
result by the second detection device is adopted. Thereby, even if
a variation range of the electric current is great, the measurement
processing device can obtain an electric current value (or
information indicating the electric current value) with high
accuracy to perform the measurement process.
[0018] In the above-constituted measurement system, various devices
can be considered as the at least one type of connected device. For
example, a battery charger that charges the battery may be provided
as the at least one type of connected device. In this system in
which the battery pack and the battery charger are connected to
each other, the measurement processing device may be configured to
perform, during discharging of the battery, the measurement process
by using a detection result by the first detection device, and
during charging of the battery by the battery charger, the
measurement process by using a detection result by the second
detection device.
[0019] That is to say, comparing a discharge current when the
battery pack is connected to another connected device and an
electric power of the battery is consumed by the another connected
device, with a charge current when the battery is charged by the
battery charger, in general, the discharge current is usually,
relatively greater than the charge current, although it depends on
a consumed electric power of the another connected device.
[0020] In view of the above, during discharge of the battery, the
detection result by the first detection device provided in the
battery pack is used, while during charge of the battery from the
battery charger, the detection result by the second detection
device provided in the battery charger is used. Thereby, even if
there is a greater difference between the discharge current and the
charge current, the measurement processing device can obtain an
electric current value (or information indicating the electric
current value) with high accuracy to perform the measurement
process.
[0021] Moreover, in the system in which the battery pack and the
battery charger are connected to each other in the above-described
manner, the battery pack may include the receiving device and the
measurement processing device. The battery charger may include the
transmission device. The measurement processing device may be
configured to perform, as the measurement process, calculation of a
remaining battery capacity of the battery.
[0022] In the above-constituted measurement system, the measurement
processing device provided in the battery pack obtains information
indicating a charge current at a time of charge, from the battery
charger. Therefore, even if a value of the charge current is small,
it is possible to obtain highly accurate information of the charge
current detected in the battery charger. For this reason, when
calculating a remaining battery capacity of the battery, the
remaining battery capacity during charge can be calculated with
high accuracy, thereby improving accuracy of the calculation as a
whole of the remaining battery capacity.
[0023] As the at least one type of connected device, for example,
an electric device to be operated by an electric power of the
battery may be provided. In the system in which the battery pack
and the battery charger are connected to each other in the
above-described manner, the battery pack may include the receiving
device and the measurement processing device. The electric device
may include the transmission device. The measurement processing
device may be configured such that, when the
detection-value-related information is received from the electric
device, the measurement processing device performs the measurement
process by using the detection-value-related information received
from the electric device, and when the detection-value-related
information is not received from the electric device, the
measurement processing device performs the measurement process by
using a detection result of the first detection device.
[0024] As explained above, the measurement processing device
provided in the battery pack generally uses the detection result by
the detection device provided in the battery pack (the first
detection device), and also uses, if the detection-value-related
information is received from the electric device, the received
detection-value-related information. With this configuration, it is
also possible to obtain the discharge current during discharge to
the electric device, with high accuracy.
[0025] Such a configuration is especially effective in a case where
the value of the discharge current is a small value with respect to
the measurement range provided in the battery pack, such as when a
rated power of the electric device is small or when the electric
device is operated under light load. Moreover, in such a case, if
the measurement processing device is configured to perform, as the
measurement process, calculation of a remaining battery capacity of
the battery, it is possible to obtain even the discharge current
having a small value with high accuracy so as to reflect the
obtained discharge current in the calculation of the remaining
battery capacity. Therefore, an improved accuracy of the
calculation of the remaining battery capacity can be achieved.
[0026] Furthermore, if the physical quantity as a detection object
is an electric current, the transmission device may transmit
information directly indicating the detected electric current
value. However, the transmission device may transmit, for example,
a result of time-integration of (integrating) the electric current
value, as information indirectly indicating the electric current
value.
[0027] That is to say, the second device may include an
electric-current integration device configured to calculate an
electric-current integration value by performing a time-integration
of a value of an electric current detected by one of the first
detection device and the second detection device, the one being
provided in the second device. In this case, the transmission
device is configured to transmit the electric-current integration
value calculated by the electric-current integration device, as the
detection-value-related information.
[0028] As explained above, the measurement system is configured to
perform, as the measurement process, a process using the
electric-current integration value, not by transmitting the
detection result, as it is, of an electric current, but by
transmitting the detection result as the electric-current
integration value. In this case, a calculation load in the
measurement process can be reduced. Moreover, if the
electric-current integration value in the second device is intended
to be calculated in the first device, it is necessary to obtain the
electric current value from the second device in a relatively short
cycle (i.e., receive the electric current value that has been
transmitted from the second device) and perform time-integration of
the obtained electric current value. This causes a very frequent
communication between the battery pack and the connected
device.
[0029] In this regard, if the electric-current integration value is
transmitted to a receiving-side device, the receiving-side device
does not need to perform time-integration of the electric current
value. Thus, the frequency of the communication can be reduced.
[0030] Moreover, the above-described calculation of the remaining
battery capacity can be performed based on a result of a time
integration of the electric current value. Therefore, if it is
configured such that calculation of the remaining battery capacity
is performed as the measurement process, the electric-current
integration value is transmitted as the detection-value-related
information; this configuration is more effective in terms of both
load in the measurement process and load in the communication.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The invention will now be described below, by way of
example, with reference to the accompanying drawings, in which:
[0032] FIG. 1 is a configuration diagram showing a schematic
configuration of a battery pack and a battery charger of the
present embodiment;
[0033] FIG. 2 is a configuration diagram showing a schematic
configuration of the battery pack and an electric power tool of the
present embodiment;
[0034] FIG. 3 is a flowchart showing a remaining-battery-capacity
calculation process executed by a battery controller of the battery
pack;
[0035] FIG. 4 is a flowchart showing a charge-capacity transmission
process executed by a charge controller of the battery charger;
[0036] FIG. 5 is a flowchart showing a discharge-capacity
transmission process executed by a motor controller of the electric
power tool;
[0037] FIG. 6 is a flowchart showing a battery-voltage transmitting
process executed by the battery controller of the battery pack;
and
[0038] FIG. 7 is a flowchart showing a battery-voltage obtaining
process executed by the charge controller of the battery
charger.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] The present embodiment is an embodiment in which the present
invention is applied to calculation of a remaining battery capacity
of a battery in a battery pack of an electric power tool.
[0040] As shown in FIG. 1, a battery pack 1 contains a battery
(rechargeable battery) 11. When being connected to a battery
charger 3, the battery pack 1 is configured to be able to charge
the battery 11 from the battery charger 3. FIG. 1 shows a state
where the battery pack 1 is attached to the battery charger 3
thereby to electrically connect the battery pack 1 and the battery
charger 3 to each other.
[0041] As shown in FIG. 2, the battery pack 1 is configured to be
attachable to and detachable from an electric power tool 5. When
being attached to the electric power tool 5, the battery pack 1 can
operate the electric power tool 5 by supplying an electric power of
the battery 11 to the electric power tool 5. FIG. 2 shows a state
where the battery pack 1 is attached to the electric power tool 5
thereby to electrically connect the battery pack 1 and the electric
power tool 5 to each other.
[0042] Hereinafter, specific configurations of the battery pack 1,
the battery charger 3, and the electric power tool 5 will be
described with reference to FIGS. 1 and 2.
[0043] The battery pack 1 is attachable to and detachable from the
electric power tool 5 (see FIG. 2) as well as other various
electric equipments (not shown), and is used as a power source for
the electric power tool 5 and the various electric devices.
[0044] The battery pack 1 is, as shown in FIGS. 1 and 2, provided
with the battery 11, a monitoring IC 12, a battery controller 13, a
battery-side current detection circuit 14, a positive electrode
terminal 21, a negative electrode terminal 22, a first signal
terminal 23, and a second signal terminal 24.
[0045] The battery 11 is constituted of a plurality of (four in the
present embodiment) battery cells 16 to 19 connected in series.
Each of the battery cells 16 to 19 of the present embodiment is a
lithium-ion rechargeable battery that generates a direct current
(DC) voltage of 3.6 V on a standalone basis. Accordingly, the
battery 11 as a whole generates a DC voltage of 14.4 V. The
configuration of the battery 11 shown in FIG. 1 is merely one
example, and a number, a connection state, a voltage, etc., of
battery cells constituting the battery 11 should not be limited to
the configuration in FIG. 1.
[0046] A positive electrode of the battery 11 (i.e., positive
electrode of the battery cell 16 on a highest potential side) is
connected to the positive electrode terminal 21. A negative
electrode of the battery 11 (i.e., negative electrode of the
battery cell 19 on a lowest potential side) is connected to the
negative electrode terminal 22 via the battery-side current
detection circuit 14.
[0047] The monitoring IC 12 is an integrated circuit (IC) for
monitoring the battery 11. The monitoring IC 12 has functions, such
as a function of detecting a voltage of the battery 11 to output
the detected voltage to the battery controller 13, and a function
of monitoring a voltage of each of the battery cells 16 to 19 of
the battery 11 and, when at least one of the voltages of the
battery cells 16 to 19 is in an overvoltage state, outputting to
the battery controller 13 a signal (overvoltage signal) indicating
generation of the overvoltage.
[0048] The battery-side current detection circuit 14 is provided in
a current path extending from the negative electrode terminal 22 to
the negative electrode of the battery 11. The battery-side current
detection circuit 14 detects a value of an electric current flowing
through this current path, i.e., a value of a charge current to be
charged to the battery 11 and a value of a discharge current
discharged from the battery 11.
[0049] The battery-side current detection circuit 14 of the present
embodiment includes a shunt resistor provided in the current path
extending from the negative electrode terminal 22 to the negative
electrode of the battery 11. The battery-side current detection
circuit 14 is configured to output a voltage between both ends of
the shunt resistor, as a signal indicating a value of an electric
current flowing through the shunt resistor, to the battery
controller 13.
[0050] Used as the shunt resistor of the battery-side current
detection circuit 14 is a resistor that has a resistance value
relatively smaller than a resistance value of a shunt resistor of a
battery-charger-side current detection circuit 34, which will be
described later, and a resistance value of a shunt resistor of a
power-tool-side current detection circuit 54 (see FIG. 2), which
will be described later. Accordingly, a measurement range of the
battery-side current detection circuit 14 is relatively higher than
measurement ranges of the battery-charger-side current detection
circuit 34 and the power-tool-side current detection circuit
54.
[0051] More specifically, in the present embodiment, the
battery-side current detection circuit 14 of the battery pack 1 has
a higher measurement range of about 100 A and is capable of
detecting an electric current of up to 100 A. The reason why the
battery-side current detection circuit 14 has the higher
measurement range as described above is that, among various
electric power tools to which the battery pack 1 can be attached,
there exists a high-load (high output) electric power tool that
operates by receiving a supply of an electric current of around 100
A at a maximum. In order to allow detection of such a large
electric current, the measurement range of the battery-side current
detection circuit 14 is set to be high.
[0052] On the other hand, the battery-charger-side current
detection circuit 34 of the battery charger 3 and the
power-tool-side current detection circuit 54 of the electric power
tool 5 have the respective measurement ranges that are low and
about 10 A. The reason why the battery-charger-side current
detection circuit 34 has the low measurement range as described
above is that a value of a charge current used to charge the
battery pack 1 from the battery charger 3 is around 10 A at
most.
[0053] Although detailed explanations will be given later, the
battery pack 1 is configured to calculate a value of a remaining
battery capacity of the battery 11, based on a value of the
discharge current from the battery 11 and a value of the charge
current to the battery 11. Therefore, the battery pack 1 is
configured to calculate a value of a discharge capacity during
discharge by using a detection result by the battery-side current
detection circuit 14 provided in the battery pack 1. Moreover, the
battery pack 1 is configured to calculate a value of a charge
capacity during charge by using a detection result by the
battery-charger-side current detection circuit 34 provided in the
battery charger 3.
[0054] It is also possible to detect a charge current during charge
by the battery-side current detection circuit 14 of the battery
pack 1. Therefore, the battery pack 1 can also calculate a value of
the charge capacity during charge by using the detection result by
the battery-side current detection circuit 14 provided in the
battery pack 1.
[0055] However, as described above, the measurement range of the
battery-side current detection circuit 14 is high and about 100 A.
Thus, if a low electric current of about 10 A is detected by the
detection circuit having such a high measurement range, it would be
difficult to obtain a highly accurate detection result.
Consequently, it is difficult to calculate the value of the charge
capacity with high accuracy, resulting in difficulty of calculating
the value of the remaining battery capacity of the battery 11 with
high accuracy.
[0056] In view of the above, in the present embodiment, the
battery-charger-side current detection circuit 34 having the low
measurement range is provided in the battery charger 3 so that the
value of the charge current during charge can be detected with high
accuracy in the battery-charger-side current detection circuit 34.
The battery pack 1 is configured to obtain a detection result by
the battery-charger-side current detection circuit 34 during charge
(specifically, by obtaining a time-integrated value of the
detection results) to calculate the value of the charge
capacity.
[0057] Moreover, compared with various electric power tools to
which the battery pack 1 can be attached, the electric power tool 5
(see FIG. 2) of the present embodiment has a smaller rated current.
In this electric power tool 5, a value of an electric current
supplied from the battery pack 1 during operation is about 10 A at
most, which is substantially the same as the value of the charge
current. Thus, in a case where the battery pack 1 is attached to
the electric power tool 5 to operate the electric power tool 5, if
a smaller discharge current to the electric power tool 5 is
detected by the battery-side current detection circuit 14 of the
battery pack 1, the same problem as that described with respect to
the charge current (i.e., deterioration of detection accuracy)
arises.
[0058] In view of the above, in the present embodiment, the
power-tool-side current detection circuit 54 having the lower
measurement range is provided in the electric power tool 5 having a
smaller rated power, so that a value of a discharge current to the
electric power tool 5 is detected with high accuracy by this
power-tool-side current detection circuit 54. Moreover, it is
configured such that the battery pack 1 obtains a detection result
by the power-tool-side current detection circuit 54 during
discharge to the electric power tool 5 (specifically, obtain a
time-integrated value of the detection results) to calculate the
value of the charge capacity. Here, specific numerical values of
each of the aforementioned electric currents and each of the
measurement ranges are merely one example.
[0059] The battery controller 13 has various functions including a
function of obtaining a voltage of the battery 11 from the
monitoring IC 12 to monitor a battery voltage, a function of
performing a predetermined protection operation when the
overvoltage signal has been inputted from the monitoring IC 12, and
a remaining-battery-capacity calculation function that calculates a
value of the remaining battery capacity of the battery 11.
[0060] In the present embodiment, the battery controller 13 is
constituted of a microcomputer. However, the battery controller 13
may be constituted in various forms, for example, may be
constituted of an IC (control IC) formed of various logic circuits,
etc. A charge controller 33 and a motor controller 53, both of
which will be described later, may be constituted in various forms
in the same manner as in the battery controller 13.
[0061] The battery controller 13 is connected to the first signal
terminal 23 and is configured to be capable of performing data
communication with the battery charger 3 and the electric power
tool 5 via the first signal terminal 23. That is to say, when the
battery pack 1 is attached to the battery charger 3, the first
signal terminal 23 of the battery pack 1 is connected to a first
signal terminal 43 of the battery charger 3, thereby allowing data
communication with the charge controller 33 of the battery charger
3. As a result, the battery controller 13 can obtain a value of the
charge capacity from the charge controller 33.
[0062] The battery controller 13 is also connected to the second
signal terminal 24. It is configured such that, through this second
signal terminal 24, a battery-charger connection signal CHG
(voltage: Vdd) can be inputted to the battery controller 13 from
the battery charger 3. That is, when the battery pack 1 is attached
to the battery charger 3, the second signal terminal 24 of the
battery pack 1 is connected to a second signal terminal 44 of the
battery charger 3. Thus, when a control voltage Vdd is generated in
the battery charger 3, the control voltage Vdd is inputted as the
battery-charger connection signal CHG to the battery controller 13.
The battery controller 13 can detect whether or not connection to
the battery charger 3 is established based on whether or not the
battery-charger connection signal CHG has been inputted.
[0063] Although the remaining-battery-capacity calculation function
provided in the battery controller 13 will be described later in
detail with reference to FIGS. 3 to 5, a brief overview thereof is
as follows. The battery controller 13 performs time-integration of
(i.e., integrates) the value of the electric current detected by
and inputted from the battery-side current detection circuit 14,
thereby calculating an amount of change in a capacity of the
battery 11.
[0064] In the present embodiment, it is configured such that, while
charging from the battery charger 3 is performed, the value of the
charge capacity is inputted to the battery controller from the
battery charger 3 by data communication. Therefore, with respect to
a capacity of a charge to be charged to the battery 11 during
charge, the battery controller 13 obtains the value of the charge
capacity, which is received from the battery charger 3, and uses
the obtained value to calculate a value of the remaining battery
capacity.
[0065] Accordingly, basically, during discharge, the battery
controller 13 performs time-integration of the value of the
electric current (discharge current) detected by the battery-side
current detection circuit 14, thereby calculating a value of the
discharge capacity; on the other hand, during charge, the battery
controller 13 obtains the value of the charge capacity transmitted
from the battery charger 3. This value of the charge capacity is a
value calculated by the charge controller 33 based on a value of
the electric current (a charge current value) detected by the
battery-charger-side current detection circuit 34. Then, the
battery controller 13 calculates a value of the remaining battery
capacity of the battery 11, for example, by deducting the value of
the discharge capacity from or adding the value of the charge
capacity to a value of the charge capacity (a fully-charged
capacity value) of the battery 11 in a fully-charged state.
[0066] However, since the electric power tool 5 shown in FIG. 2 has
a small rated power, the electric power tool 5 is configured to
calculate a value of the discharge capacity by the electric power
tool 5 itself and transmit the calculated value of the discharge
capacity to the battery pack 1. Therefore, when the battery pack 1
is connected to the electric power tool 5 and supplies an electric
power to the electric power tool 5, the battery pack 1 obtains the
value of the discharge capacity transmitted from the electric power
tool 5 to calculate a value of the remaining battery capacity.
[0067] The battery pack 1 is further provided with a power supply
circuit, which is not shown. The power supply circuit is configured
to lower a voltage of the battery 11 to generate a control voltage
having a predetermined voltage value. The monitoring IC 12 and the
battery controller 13 are operated by this control voltage.
[0068] Next, the battery charger 3 will be described. The battery
charger 3 is, as shown in FIG. 1, provided with an input rectifier
circuit 31, a charging switching power supply circuit 32, the
charge controller 33, the battery-charger-side current detection
circuit 34, a voltage detection circuit 35, a control power
generation circuit 36, a positive electrode terminal 41, a negative
electrode terminal 42, the first signal terminal 43, and the second
signal terminal 44.
[0069] The input rectifier circuit 31 rectifies an alternate
voltage supplied from an alternating current (AC) power source such
as a commercial power source. Such a rectified output is outputted
to the charging switching power supply circuit 32 and the control
power generation circuit 36.
[0070] The charging switching power supply circuit 32 is a
switching power supply circuit that generates a direct-current
charging power to be charged to the battery 11 based on an output
from the input rectifier circuit 31. The charging switching power
supply circuit 32 is drive-controlled by the charge controller
33.
[0071] The battery-charger-side current detection circuit 34 is
provided in a current path extending from the negative electrode
terminal 42 to a negative terminal among positive and negative
output terminals (not shown) of the charging switching power supply
circuit 32. The battery-charger-side current detection circuit 34
detects a value of an electric current flowing through this current
path, i.e., a value of a charge current to be charged to the
battery 11.
[0072] The battery-charger-side current detection circuit 34 of the
present embodiment includes a shunt resistor provided in the
current path extending from the negative electrode terminal 42 to
the negative terminal of the charging switching power supply
circuit 32. The battery-charger-side current detection circuit 34
is configured to output a voltage between both ends of the shunt
resistor, as a signal indicating a value of an electric current
flowing through the shunt resistor, to the charge controller
33.
[0073] The value of the charge current used to charge the battery
by the battery charger 3 of the present embodiment is, as described
above, around 10 A at most. Thus, the shunt resistor of the
battery-charger-side current detection circuit 34 has a resistance
value relatively greater than the resistance value of the shunt
resistor of the battery-side current detection circuit 14 in the
battery pack 1. That is to say, the measurement range of the
battery-charger-side current detection circuit 34 is relatively
lower than the measurement range of the battery-side current
detection circuit 14 and is, for example, about 10 A in the present
embodiment.
[0074] The voltage detection circuit 35 detects a value of the
voltage (battery voltage) of the battery 11 in the battery pack 1
and inputs a signal indicating the value of the detected battery
voltage to the charge controller 33.
[0075] The control power generation circuit 36 is a switching power
supply circuit that generates a predetermined control voltage Vdd
(for example, DC 3.3 V) based on an output from the input rectifier
circuit 31. The control voltage Vdd generated by the control power
generation circuit 36 is used as a power source for operating the
charge controller 33; in addition, when the battery pack 1 is
attached to the battery charger 3, the control voltage Vdd
generated by the control power generation circuit 36 is outputted
from the second signal terminal 44 to the battery pack 1, as the
battery-charger connection signal CHG.
[0076] In the present embodiment, the charge controller 33 is
constituted of a microcomputer as in the battery controller 13
inside the battery pack 1. The charge controller 33 drive-controls
the charging switching power supply circuit 32, based on various
information received from the battery controller 13 in the battery
pack 1 by data communication or based on the value of the battery
voltage detected by the voltage detection circuit 35, thereby
controlling a charge pattern (charge current, charge voltage, etc.)
to the battery 11.
[0077] Moreover, the charge controller 33 performs time-integration
of (i.e., integrates) the value of the electric current (charge
current) detected by the battery-charger-side current detection
circuit 34 for each predetermined period of time, thereby
calculating a value of the charge capacity that has been charged to
the battery 11 for the predetermined period of time. The charge
controller 33 then transmits the calculated value of the charge
capacity from the first signal terminal 43 to the battery pack
1.
[0078] Next, the electric power tool 5 will be described. The
electric power tool 5 includes, as shown in FIG. 2, a motor 51, a
drive switching element 52, the motor controller 53, the
power-tool-side current detection circuit 54, a trigger switch 55,
a positive electrode terminal 61, a negative electrode terminal 62,
and a signal terminal 63.
[0079] The positive electrode terminal 61 is connected to one end
of the motor 51 via the trigger switch 55. The negative electrode
terminal 62 is connected to the other end of the motor 51 via the
power-tool-side current detection circuit 54 and the drive
switching element 52.
[0080] The motor 51 of the present embodiment is a brushed direct
current (DC) motor. Moreover, the motor 51 of the present
embodiment has a small rated power, and a value of an electric
current during operation of the motor 51 is around 10 A at most.
Among various electric power tools that are used with the battery
pack 1 attached thereto, some of the electric power tools have a
large rated power and a value of an electric current during
operation thereof reaches around 100 A at a maximum. Comparing with
the some of the electric power tools, the electric power tool 5 of
the present embodiment is considered to be an electric power tool
having a smaller rated power.
[0081] The trigger switch 55 is turned on and off when a user
operates a trigger, which is not shown, provided in the electric
power tool 5. Specifically, the trigger switch 55 is turned on when
the user pulls the trigger, while the trigger switch 55 is turned
off when the user releases the trigger. Information on on-and-off
states of the trigger switch 55 is inputted to the motor controller
53.
[0082] When the trigger switch 55 is turned on, the motor
controller 53 turns on the drive switching element 52 to start
conduction of electric current from the battery pack 1 to the motor
51, thereby operating the motor 51. When the trigger switch 55 is
turned off, the motor controller 53 turns off the drive switching
element 52 to interrupt the conduction of electric current to the
motor 51. Here, the drive switching element 52 is an N-channel
MOSFET in the present embodiment; however, this is merely one
example.
[0083] The power-tool-side current detection circuit 54 is provided
in a current path extending from the negative electrode terminal 62
to the drive switching element 52. The power-tool-side current
detection circuit 54 detects a value of an electric current flowing
through this current path, i.e., a value of a discharge current
discharged from the battery 11 to the motor 51.
[0084] The power-tool-side current detection circuit 54 of the
present embodiment includes a shunt resistor provided in the
current path extending from the negative electrode terminal 62 to
the drive switching element 52. The power-tool-side current
detection circuit 54 is configured to output a voltage between both
ends of the shunt resistor, as a signal indicating a value of an
electric current flowing through the shunt resistor, to the motor
controller 53.
[0085] The value of the discharge current when the electric power
tool 5 in the present embodiment is operated is, as described
above, around 10 A at most. Thus, the shunt resistor of the
power-tool-side current detection circuit 54 has a resistance value
relatively greater than the resistance value of the shunt resistor
of the battery-side current detection circuit 14 in the battery
pack 1. That is to say, the measurement range of the
power-tool-side current detection circuit 54 is relatively lower
than the measurement range of the battery-side current detection
circuit 14 and is, for example, about 10 A in the present
embodiment.
[0086] The motor controller 53 performs time-integration of (i.e.,
integrates) the value of the electric current (discharge current)
detected by the power-tool-side current detection circuit 54 for
each predetermined period of time, thereby calculating a value of
the discharge capacity that has been discharged from the battery 11
for the predetermined period of time. Then, the motor controller 53
transmits the calculated value of the discharge capacity from the
signal terminal 63 to the battery pack 1.
[0087] Next, the remaining-battery-capacity calculation function
provided in the battery controller 13 of the battery pack 1 will be
described in more detail with reference to flowcharts in FIGS. 3 to
5.
[0088] FIG. 3 shows a remaining-battery-capacity calculation
process that is executed by the battery controller 13 to calculate
a value of the remaining battery capacity of the battery 11. Before
describing this remaining-battery-capacity calculation process, a
charge-capacity transmission process to be executed in the battery
charger 3 and a discharge-capacity transmission process to be
executed in the electric power tool 5 will be described.
[0089] First, explanations will be given with respect to the
charge-capacity transmission process executed by the charge
controller 33 in the battery charger 3, with reference to FIG.
4.
[0090] In a memory (not shown) provided in the charge controller
33, a program for the charge-capacity transmission process in FIG.
4 is stored. When a CPU (not shown) provided in the charge
controller 33 starts operating by receiving a supply of the control
voltage Vdd, the CPU executes the charge-capacity transmission
process in FIG. 4.
[0091] When the charge-capacity transmission process in FIG. 4 is
started, first in S210, the charge controller 33 determines whether
or not charging of the battery 11 is being performed. Since the
charge controller 33 has a basic function of controlling charging
to the battery 11, understandably, the charge controller 33 itself
can determine whether or not charging is being performed.
[0092] While charging is not performed (S210: NO), this
determination process of S210 is repeatedly performed. On the other
hand, if charging is being performed (S210: YES), in S220, a
charge-current value Ic is detected. Specifically, a detection
result of an electric current is obtained from the
battery-charger-side current detection circuit 34. Based on this
detection result, the charge-current value Ic is detected.
[0093] Then, in S230, a charge-capacity value Cc is calculated.
During charge, this process of S230 is performed each time a
predetermined time interval .DELTA.t has elapsed. The
charge-capacity value Cc is calculated in S230 by the following
formula (1).
Cc=Cc+Ic.DELTA.t (1)
[0094] That is, each time the time interval .DELTA.t has elapsed,
the charge-capacity value Cc calculated at the current time
interval .DELTA.t is added in a cumulative manner (i.e.,
time-integrated) to the charge-capacity value Cc calculated at the
previous time interval .DELTA.t.
[0095] Then, in S240, it is determined whether or not a
transmission timing has been reached. The transmission timing is a
timing that is reached in a predetermined cycle, which is at least
greater than the aforementioned .DELTA.t (for example, tens to
several hundreds of times of .DELTA.t).
[0096] If the transmission timing has not been reached (S240: NO),
it is determined in S250 whether or not charging is being
performed. When charging is being performed, the process returns to
S220. In other words, while charging is performed, the calculations
in S220 and S230 are repeated until the transmission timing has
been reached, thereby time-integrating the charge-capacity value
Cc.
[0097] If the transmission timing has been reached (S240: YES) or
if charging is stopped although the transmission timing has not yet
been reached (S250: NO), in S260, the charge-capacity value Cc that
is currently calculated is transmitted to the battery pack 1. In
S270, the currently calculated charge-capacity value Cc is set to
"0" and thereafter, the process returns to S210.
[0098] Next, the discharge-capacity transmission process executed
by the motor controller 53 of the electric power tool 5 will be
described with reference to FIG. 5.
[0099] In a memory (not shown) provided in the motor controller 53,
a program for the discharge-capacity transmission process in FIG. 5
is stored. When a CPU (not shown) provided in the motor controller
53 starts operating, the CPU executes the discharge-capacity
transmission process in FIG. 5.
[0100] When the discharge-capacity transmission process in FIG. 5
is started, first in S310, the motor controller 53 determines
whether or not discharging is being performed, i.e., whether or not
discharging from the battery pack 1 to the motor 51 is being
performed. This determination can be performed, for example, based
on a detection result by the power-tool-side current detection
circuit 54 or based on whether or not the trigger switch 55 is
turned on.
[0101] While discharging is not performed (S310: NO), this
determination process in S310 is repeatedly performed. On the other
hand, if discharging is being performed (S310: YES), in S320, a
discharge-current value Idx is detected. Specifically, a detection
result of an electric current is obtained from the power-tool-side
current detection circuit 54. Based on the detection result, the
discharge-current value Idx is detected.
[0102] Then, in S330, a discharge-capacity value Cdx is calculated.
During discharge, this process of S330 is performed each time a
predetermined time interval .DELTA.t has elapsed. The
discharge-capacity value Cdx is calculated in S330 by the following
formula (2).
Cdx=Cdx+Idx.DELTA.t (2)
[0103] That is, in the same manner as in the process of S230 in
FIG. 4 in the battery charger 3, each time the time interval
.DELTA.t has elapsed, the discharge-capacity value Cdx calculated
at the current time interval .DELTA.t is added in a cumulative
manner (i.e., time-integrated) to the discharge-capacity value Cdx
calculated at the previous time interval .DELTA.t.
[0104] Then, in S340, it is determined whether or not a
transmission timing has been reached. In the same manner as in the
process of S240 in FIG. 4 in the battery charger 3, the
transmission timing is a timing that is reached in a predetermined
cycle, which is at least greater than the aforementioned .DELTA.t
(for example, tens to several hundreds of times of .DELTA.t).
[0105] If the transmission timing has not been reached (S340: NO),
it is determined in S350 whether or not discharging is being
performed. When discharging is being performed, the process returns
to S320. In other words, while discharging is performed, the
calculations in S320 and S330 are repeated until the transmission
timing has been reached, thereby time-integrating the
discharge-capacity value Cdx.
[0106] If the transmission timing has been reached (S340: YES) or
if discharging is stopped although the transmission timing has not
yet been reached (S350: NO), in S360, the discharge-capacity value
Cdx that is currently calculated is transmitted to the battery pack
1. In S370, the currently calculated discharge-capacity value Cdx
is set to "0" and thereafter, the process returns to S310.
[0107] Next, the remaining-battery-capacity calculation process
executed by the battery controller 13 in the battery pack 1 will be
described with reference to FIG. 3.
[0108] In a memory (not shown) provided in the battery controller
13, a program for the remaining-battery-capacity calculation
process in FIG. 3 is stored. When a CPU (not shown) provided in the
battery controller 13 starts operating, the CPU executes the
remaining-battery-capacity calculation process in FIG. 3.
[0109] When the remaining-battery-capacity calculation process in
FIG. 3 is started, first in S110, the battery controller 13
determines whether or not discharging is being performed, i.e.,
whether or not discharging is being performed from the battery 11.
This determination can be performed, for example, based on a
detection result by the battery-side current detection circuit 14,
contents of communication between the battery controller 13 and
other external microcomputers, or presence or absence of the
battery-charger connection signal CHG from the battery charger
3.
[0110] While discharging is not performed (S110: NO), it is
determined in S180 whether or not charging is being performed,
i.e., whether or not charging of the battery 11 is being performed
by the battery charger 3. This determination can be performed in
the same manner as in S110.
[0111] If charging is not being performed (S180: NO), the process
returns to S110. If charging is being performed (S180: YES), it is
determined in S190 whether or not calculated data of the
charge-capacity value Cc has been received from the battery charger
3. If the calculated data of the charge-capacity value Cc has not
been received (S190: NO), the process returns to S110. If the
calculated data of the charge-capacity value Cc has been
transmitted from the battery charger 3 and this transmitted
calculated data has been received (S190: YES), in S200, a remaining
battery capacity value C of the battery 11 is calculated.
Specifically, the remaining battery capacity value C is calculated
by the following formula (3).
C=C+Cc (3)
[0112] That is, by adding the newly received charge-capacity value
Cc to the current remaining battery capacity value C, the remaining
battery capacity value C is updated. Here, an initial value of the
remaining battery capacity value C may be set, for example, such
that a remaining battery capacity at a time of manufacturing of the
battery pack 1 is measured and such a measured value is set as an
initial value of the remaining battery capacity value C.
Alternatively, each time the battery 11 is charged by the battery
charger 3 to reach a predetermined capacity (e.g., a fully charged
state), a value of the capacity at such a time may be set as an
initial value of the remaining battery capacity value C. After the
remaining battery capacity value C is calculated in S200, the
process returns to S110.
[0113] On the other hand, if it is determined in S110 that
discharging is being performed (S110: YES), it is determined in
S120 whether or not calculated data (Cdx) of a discharge-capacity
value Cd is being communicated.
[0114] The electric power tool 5 of the present embodiment has a
function in which the electric power tool 5 itself calculates a
discharge-capacity value Cdx and transmits the calculated
discharge-capacity value Cdx to the battery pack 1. Therefore, when
the battery pack 1 is attached to the electric power tool 5, a
predetermined communication process is executed between the battery
controller 13 and the motor controller 53. Then, the battery
controller 13 makes a preparation for receiving the
discharge-capacity value Cdx from the electric power tool 5, while
the motor controller 53 of the electric power tool 5 makes a
preparation for transmitting the calculated data of the
discharge-capacity value Cdx.
[0115] As described above, when the battery controller 13 makes the
preparation for receiving the discharge-capacity value Cdx from an
external device by communicating with a device to be connected, the
battery controller 13 determines in S120 that the communication is
being performed (S120: YES) (i.e., the discharge-capacity value Cdx
is to be supplied from the external device). Then, the process
proceeds to S160.
[0116] In S160, it is determined whether or not the calculated data
of the discharge-capacity value Cdx has been received from the
external device (e.g., the electric power tool 5, etc.). If the
calculated data of the discharge-capacity value Cdx is not received
(S160: NO), the process returns to S110. If, for example, when the
battery pack 1 is attached to the electric power tool 5, the
calculated data of the discharge-capacity value Cdx has been
transmitted from the electric power tool 5 and then received (S160:
YES), in S170, a remaining battery capacity value C of the battery
11 is calculated. Specifically, the remaining battery capacity
value C is calculated by the following formula (4).
C=C-Cdx (4)
[0117] That is, by deducting the newly received discharge-capacity
value Cdx from the current remaining battery capacity value C, the
remaining battery capacity value C is updated. After the remaining
battery capacity value C is calculated in S170, the process returns
to S110.
[0118] On the other hand, if it is determined in S120 that the
communication of the calculated data Cdx of the discharge-capacity
value Cd is not being performed (S120: NO), the process proceeds to
S130 to calculate the discharge-capacity value Cd by the battery
controller 13 itself. In S130, a discharge-current value Ido is
detected. Specifically, a detection result of an electric current
is obtained from the battery-side current detection circuit 14.
Based on the detection result, the discharge-current value Ido is
detected.
[0119] Then, in S140, a discharge-capacity value Cdo is calculated.
During discharge, this process of S140 is performed each time a
predetermined time interval .DELTA.t has elapsed. The
discharge-capacity value Cdo is calculated in S140 by the following
formula (5).
Cdo=Ido.DELTA.t (5)
[0120] Then, in S150, the calculated discharge-capacity value Cdo
is used to calculate a remaining battery capacity value C.
Specifically, the remaining battery capacity value C is calculated
by the following formula (6).
C=C-Cdo (6)
[0121] That is, by deducting the calculated discharge-capacity
value Cdo between the previous time interval .DELTA.t and the
current time interval .DELTA.t, from the current remaining battery
capacity value C, the remaining battery capacity value C is
updated. After the remaining battery capacity value C is calculated
in S150, the process returns to S110.
[0122] As described above, the battery pack 1 of the present
embodiment performs calculation of the remaining battery capacity
value C basically as follows: during discharge, the battery
controller 13 calculates the remaining battery capacity value C by
using the discharge-capacity value Cdo detected and calculated by
the battery controller 13 itself, and during charge, the battery
controller 13 calculates the remaining battery capacity value C by
using the charge-capacity value Cc received from the battery
charger 3.
[0123] However, as in the electric power tool 5 of the present
embodiment shown in FIG. 2, if the battery controller 13 is
connected to an equipment, etc. configured to detect and calculate
the discharge-capacity value Cdx so as to transmit such a
discharge-capacity value Cdx to the battery pack 1, the battery
controller 13 calculates the remaining battery capacity value C by
using the discharge-capacity value Cdx received from the equipment,
etc.
[0124] The measurement range of the battery-side current detection
circuit 14 in the battery pack 1 is set to have a relatively high
value (about 100 A in the present embodiment). This is because
there may be a case where a large electric current flows from the
battery pack 1 depending on an electric power tool to which the
battery pack 1 is to be connected. For this reason, if a value of
the electric current is small, such as the charge current from the
battery charger 3 and the discharge current to the electric power
tool 5, it is difficult to accurately detect such a small value of
the electric current.
[0125] In view of the above, in the battery charger 3 and the
electric power tool 5, the respective current detection circuits
having the lower measurement ranges (about 10 A in the present
embodiment) are provided. The value of the charge current from the
battery charger 3 is detected by the battery-charger-side current
detection circuit 34 that has the low measurement range and that is
provided in the battery charger 3. Based on this detected value of
the charge current, the charge controller 33 calculates a value of
the charge capacity.
[0126] Moreover, with respect to the discharge current to the
electric power tool 5, the value of the discharge current is
detected by the power-tool-side current detection circuit 54 that
has the low measurement range and that is provided in the electric
power tool 5. Based on this detected value of the discharge
current, the motor controller 53 calculates a value of the
discharge capacity.
[0127] As above, both of the value of the charge capacity
calculated by the battery charger 3 and the value of the discharge
capacity calculated by the electric power tool 5 are highly
accurate.
[0128] In this way, with the simple configuration in which the
respective current detection circuits having the lower measurement
ranges are provided in the battery charger 3 and the electric power
tool 5 so as to obtain calculated results of respective values of
the charge capacity and discharge capacity from the respective
current detection circuits by data communication, it can be
achieved to calculate the remaining battery capacity value C of the
battery 11 with high accuracy by the battery controller 13.
[0129] That is to say, even if the electric current flowing through
the battery 11 varies over a great range, it is possible to detect
a value of such an electric current with high accuracy. Moreover,
based on the detected value of the electric current, it is possible
to calculate a value of the discharge capacity or a value of the
charge capacity with high accuracy. Consequently, the remaining
battery capacity value C can be calculated with high accuracy.
[0130] Moreover, when the battery controller 13 calculates the
remaining battery capacity value C of the battery 11, it is not
absolutely necessary that a calculated result of the value of the
charge capacity is transmitted to the battery controller 13 from
the battery charger 3. It may be possible that data of the value of
the charge current detected in the battery charger 3 is transmitted
to the battery controller 13 so that the battery controller 13 can
calculate a value of the charge capacity by using the transmitted
data.
[0131] Likewise, in the electric power tool 5, it is not absolutely
necessary that a calculated result of the value of the discharge
capacity is transmitted to the battery controller 13 from the
electric power tool 5. It may be possible that data of the value of
the discharge current detected in the electric power tool 5 is
transmitted to the battery controller 13 so that the battery
controller 13 can calculate a value of the discharge capacity by
using the transmitted data.
[0132] However, in the aforementioned configuration, the battery
controller 13 needs to repeatedly obtain electric current data in a
short cycle to perform calculation (i.e., time-integration, etc.)
of a value of the capacity, causing a frequent data
communication.
[0133] In this regard, in the present embodiment, transmitted from
the battery charger 3 is, not a value of the charge current, but a
value of the charge capacity calculated based on the value of the
charge current. Moreover, transmitted from the electric power tool
5 is, not a value of the discharge current, but a value of the
discharge capacity calculated based on the value of the discharge
current. Therefore, in the present embodiment, it is possible to
reduce frequency of data communication between the battery pack 1
and a connected device to which the battery pack 1 is
connected.
[0134] Here, in the present embodiment, both the battery charger 3
and the electric power tool 5 correspond to an example of a
connected device of the present invention; specifically, the
electric power tool 5 corresponds to an example of an electric
device of the present invention. The battery-side current detection
circuit 14 corresponds to an example of a first detection device of
the present invention. Both the battery-charger-side current
detection circuit 34 and the power-tool-side current detection
circuit 54 correspond to an example of a second detection device of
the present invention. The battery controller 13 corresponds to an
example of a measurement processing device and an example of a
receiving device of the present invention. Each of the charge
controller 33 and the motor controller 53 corresponds to an example
of a transmission device and an example of an electric-current
integration device of the present invention.
[0135] Each of the process in S230 in FIG. 4 and the process in
S330 in FIG. 5 corresponds to an example of a process executed by
the electric current integration device of the present invention.
The processes in S150, S170, and S220 in FIG. 3 correspond to an
example of a process executed by the measurement processing device
of the present invention.
MODIFICATION
[0136] The embodiment of the present invention has been described
as above. However, embodiments of the present invention should not
at all be limited to the above-described embodiment. Needless to
say, the present invention can be carried out in various forms
without departing from the technical scope of the present
invention.
[0137] For example, a physical quantity as a detection object is
not limited to an electric current and may be any object that can
be detected by both the battery pack 1 and a connected device to be
connected to the battery pack 1. As a specific example, for
instance, a value of the battery voltage may be transmitted from
the battery pack 1 during charge.
[0138] When charging the battery 11, the charge controller 33 in
the battery charger 3 performs a charge control while concurrently
monitoring a voltage of the battery 11. In order to appropriately
perform the charge control, the battery voltage needs to be
detected with accuracy as high as possible. Since the battery
charger 3 includes the voltage detection circuit 35 for detection
of the battery voltage, it is, of course, possible to perform the
charge control by using a detection result by the voltage detection
circuit 35. Meanwhile, since the battery pack 1 of the present
embodiment includes the monitoring IC 12, it is possible to detect
the battery voltage by the monitoring IC 12 in a relatively highly
accurate manner. Therefore, by transmitting a battery-voltage value
detected by the monitoring IC 12 to the battery charger 3 by data
communication, the charge controller 33 can perform the charge
control with much higher accuracy.
[0139] With reference to FIGS. 6 and 7, explanations will be given
with respect to respective processes executed by the controllers 13
and 33 in a case where the battery voltage value is configured to
be transmitted to the battery charger 3 from the battery pack 1 in
the above-described manner.
[0140] When a battery-voltage transmitting process in FIG. 6 is
started, first in S410, the battery controller 13 of the battery
pack 1 determines whether or not the battery 11 is being charged.
If the battery 11 is not being charged, this battery-voltage
transmitting process is terminated. However, if the battery 11 is
being charged, it is determined in S420 whether or not a
battery-voltage transmission request has been received from the
battery charger 3 by data communication.
[0141] If the battery-voltage transmission request has not been
received from the battery charger 3, this battery-voltage
transmitting process is terminated. However, if the battery-voltage
transmission request has been received, in S430, a battery-voltage
value is detected. Specifically, a detected result of the
battery-voltage value is obtained from the monitoring IC 12. Then,
in S440, the obtained battery-voltage value is transmitted to the
battery charger 3.
[0142] When a battery-voltage obtaining process in FIG. 7 is
started, first in S510, the charge controller 33 of the battery
charger 3 transmits a battery-voltage transmission request to the
battery pack 1 by data communication. Then, it is determined in
S520 whether or not the battery-voltage value has been received
from the battery pack 1.
[0143] If it is determined that the battery-voltage value has not
been received, in S540, a battery-voltage value detected by the
voltage detection circuit 35 in the battery charger 3 is obtained
as a non-provisional battery-voltage value for control. On the
other hand, if the battery-voltage value has been received from the
battery pack 1, in S530, the received battery-voltage value is
obtained as a non-provisional battery-voltage value for
control.
[0144] The above-described battery voltage is merely one example.
The present invention can be applied to other various physical
quantities.
[0145] Moreover, the value of the electric current discharged from
the battery 11 varies, depending on a connected device to which the
battery pack 1 is connected or an operational state (load state) of
the connected device. Therefore, transmission of a detection result
(e.g., a discharge capacity, etc.) from the connected device may
not be performed constantly as in the electric power tool 5 in the
above-described embodiment, but may be performed as needed
depending on a variation range of an electric current flowing
through the connected device.
[0146] For example, it may be configured such that if a value of
the discharge current is large, the battery controller 13
calculates a value of a remaining battery capacity by using a
detection result of the battery-side current detection circuit 14
of the battery pack 1; on the other hand, if the value of the
discharge current is small, the battery controller 13 sends a
transmission request to the connected device (or, the connected
device itself determines that the value of the discharge current
has become smaller), so that data of the value of the discharge
current or the value of the discharge capacity is transmitted to
the battery controller 13 from the connected device.
[0147] Moreover, in the present embodiment, the battery controller
13 is configured to calculate by itself a value of the remaining
battery capacity of the battery 11; however, it may be configured
such that, depending on a physical quantity as a detection object,
the connected device to which the battery pack 1 is to be connected
performs, by the connected device itself, detection of the physical
quantity or various calculation processes (measurement processes),
etc., based on a result of this detection.
[0148] Furthermore, an application of the present invention is not
limited to the configuration shown in FIG. 1 in which the battery
pack 1 and the battery charger 3 are provided, and the
configuration shown in FIG. 2 in which the battery pack 1 and the
electric power tool 5 are provided. Rather, the present invention
can be applied to a configuration in which the battery pack 1 and
any connected device that can be connected (attached) to the
battery pack 1 are provided. Examples of the connected device other
than a battery charger are an electrical device, such as a
rechargeable radio, an electrical operating machine, such as a
rechargeable cleaner, and so on.
* * * * *