U.S. patent number 6,566,005 [Application Number 09/707,101] was granted by the patent office on 2003-05-20 for battery pack with an improved cooling structure.
This patent grant is currently assigned to Makita Corporation. Invention is credited to Junichi Masuda, Kazuyuki Sakakibara, Yasutoshi Shimma, Shingo Umemura.
United States Patent |
6,566,005 |
Shimma , et al. |
May 20, 2003 |
Battery pack with an improved cooling structure
Abstract
A battery pack (1) includes an air intake port (9), air
discharge ports (11), first air passages (24), and a second air
passage (25). Cooling air introduced into the battery pack through
the air intake port (9) flows around and through two cell groups
contained in the pack before exiting to the pack from the discharge
ports (11). As the intake port and the discharge ports are both
provided at an upper enclosure (4) of the battery pack that is set
on a charger (50) for charging or an electric power tool as a power
source, neither intake port nor the discharge ports are exposed to
the exterior environment whether the pack is set on the charger or
attached to a power tool.
Inventors: |
Shimma; Yasutoshi (Anjo,
JP), Masuda; Junichi (Okazaki, JP),
Umemura; Shingo (Okazaki, JP), Sakakibara;
Kazuyuki (Okazaki, JP) |
Assignee: |
Makita Corporation (Anjo,
JP)
|
Family
ID: |
18118857 |
Appl.
No.: |
09/707,101 |
Filed: |
November 6, 2000 |
Foreign Application Priority Data
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Nov 10, 1999 [JP] |
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11-320202 |
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Current U.S.
Class: |
429/148; 429/120;
429/99; 429/83; 429/71 |
Current CPC
Class: |
H01M
10/486 (20130101); H01M 10/6551 (20150401); H01M
10/613 (20150401); H01M 10/6563 (20150401); H01M
10/6566 (20150401); H01M 10/6235 (20150401); H01M
50/213 (20210101); Y02E 60/10 (20130101); H01M
10/643 (20150401) |
Current International
Class: |
H01M
10/42 (20060101); H01M 10/50 (20060101); H01M
2/10 (20060101); H01M 002/00 (); H01M 002/12 ();
H01M 010/50 () |
Field of
Search: |
;429/99,100,96,148,160,72,82,83,71,57,53,120 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 920 105 |
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Jun 1999 |
|
EP |
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920105 |
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Jun 1999 |
|
EP |
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Primary Examiner: Kalafut; Stephen
Assistant Examiner: Alejandro; Raymond
Attorney, Agent or Firm: Lahive & Cockfield, LLP
Claims
What is claimed is:
1. A battery pack comprising: an outer enclosure containing a
plurality of battery cells and having a mounting portion adapted to
be removably attached to a charger and a battery powered device; at
least one intake port provided in the mounting portion for
introducing into the battery pack cooling air supplied from a
charger; at least one discharge port provided in the mounting
portion for discharging the cooling air from the battery pack; and
at least one air passage connecting the at least one intake port to
the at least one discharge port, the at least one air passage
allowing the cooling air introduced through the at least one intake
port to flow one of along and between the cells and to be
discharged through the at least one discharge port.
2. A battery pack in accordance with claim 1, wherein the mounting
portion includes a substantially rectangular top plate having a
first edge and an opposite second edge, the at least one intake
port being formed on the top plate in proximity to the first edge
and the at least one discharge port being formed in proximity to
the second edge.
3. A battery pack in accordance with claim 1, wherein the mounting
portion is contoured to generally correspond to a connecting
portion of the charger and those of said electric devices such
that, when the battery pack is attached to any of the charger and
said electric devices, the at least one intake port and the at
least one discharge port are unexposed to the exterior environment
of the battery pack and the electric device to which the battery
pack is attached.
4. A battery pack in accordance with claim 2, wherein when the
battery pack is attached to the charger, a narrow gap is formed at
least along the second edge of the top plate between the mounting
portion of the battery pack and a connecting portion of the charger
so as to facilitate discharge of cooling air from the at least one
discharge port.
5. A battery pack in accordance with claim 4, wherein the mounting
portion includes a step along the second edge where the at least
one discharge port are provided, the step forming the narrow gap
with the connecting portion of the charger.
6. A battery pack in accordance with claim 1, further comprising an
inner case holding the cells and including a plurality of radiators
in contact with the cells, and wherein the at least one air passage
is separated from the cells by the inner case.
7. A battery pack in accordance with claim 6, wherein each radiator
is a radiator plate having a plurality of fins protruding into the
air passage and oriented substantially in parallel to the direction
of flow of cooling air introduced through the at least one intake
port.
8. A battery pack in accordance with claim 7, wherein the number of
fins of each radiator plate increases in the downstream direction
of the cooling airflow.
9. A battery pack in accordance with claim 7, further comprising a
pair of slide rails on the mounting portion, and wherein each of
the charger and the electric devices includes on a connecting
portion thereof a pair of guide rails which slidably engage the
slide rails such that the battery pack is attached to the charger
and the electric devices by slide motion.
10. A battery pack in accordance with claim 6, wherein the
plurality of cells are divided into two groups by a gap extending
from a first end portion to a second end portion of the inner case
along a longitudinal axis of the battery pack.
11. A battery pack in accordance with claim 6, wherein the outer
enclosure includes two inner longitudinal walls and the inner case
includes two outer longitudinal walls which opposes the inner
longitudinal walls across a selected distance so as to at least
partially define at least two air passages between the outer
longitudinal walls and the inner longitudinal walls.
12. A battery pack in accordance with claim 1, wherein the electric
devices include electric power tools.
13. A battery pack in accordance with claim 1, wherein the charger
includes a housing, at least one inlet port provided in the
housing, and at least one exhaust port provided in the housing, the
at least one inlet port being located in the portion of the housing
directly opposing the at least one discharge port of the battery
pack so as to allow the cooling air discharged out of the discharge
port of the battery pack to reenter the charger through the inlet
port and to be discharged from the charger through the exhaust
port.
Description
This application claims priority on Japanese Patent Application No.
11-320202 filed on Nov. 10, 1999, the contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a battery pack containing a
plurality of cells for use with a charger or battery-powered
devices, such as power tools, as a power source. More particularly,
the invention relates to a battery pack with an improved structure
for cooling the cells during a charge.
2. Description of the Related Art
A conventional battery pack includes on the top surface thereof a
mounting portion which in turn includes electrical terminals for
the establishment of electric contact between the battery pack and
a charger or a battery-powered device, such as an electric power
tool. The battery pack can be recharged by attachment of its
mounting portion onto the charger, and also can be used as a power
source by attachment of the mounting portion onto a battery-powered
device. However, the cells of the battery pack tend to generate
heat during each charge, which results in degradation of the cells.
To avoid such a disadvantage, a means for cooling the battery cells
is typically provided in the battery pack. For example, disclosed
in Japan Published Unexamined Patent Application No. 11-219733 is a
battery pack which is provided with a cooling structure therein.
The structure includes air passages running through the battery
pack case and along and between the cells within the battery pack
and a plurality of apertures forming intake and discharge ports
provided at the top and bottom portions of the battery pack,
whereby the intake ports are disposed at a mounting portion to
which a charger is attached, with the air passages in communication
with both the intake and discharge ports. Thus, cooling air from a
blower or fan incorporated in the charger can be introduced from
the intake ports to be sent into the interior of the pack through
the air passages and outside the pack from the discharge ports so
that the heat generated by the cells during a charge is dissipated
therefrom.
While the foregoing battery pack with a cooling structure for the
battery cells contained therein achieves its intended objective, it
is not free from certain problems and inconveniences, thus leaving
room for improvement. For example, in the above described
structure, foreign substances such as dust and other various types
of debris can easily enter the interior of the battery pack, as the
discharge ports, which are provided at the bottom of the battery
pack and are in communication with the air passages, are exposed in
an upward direction to the external environment when the battery
pack is mounted onto the charger for a charge. If such substances
are electrically conductive, this may result in occurrence of a
short circuit in the battery pack. Also, when the battery pack is
mounted onto battery-powered tools, not only debris but even rain
drops may enter the battery pack if such tools are used in
environments in which the tool is exposed to rain, since the pack's
bottom surface where the discharge ports are located is exposed to
the exterior environment. This also may cause rust, corrosion, or
liquid electrolyte leakage of the cells.
SUMMARY OF THE INVENTION
In view of the above-identified problems, a primary object of the
present invention is to provide a battery pack for use with a
charger or battery-powered devices which can eliminate the possible
causes of the above-identified problems by prevention of foreign
substances from intruding into the battery pack when the battery
pack is mounted onto a charger or battery-powered devices without
reducing the effect of cooling the cells during each charge.
The above objects and other related objects are realized by the
invention, which provides a battery pack including: an outer
enclosure containing a plurality of battery cells and having a
mounting portion adapted to be removably attached to a charger and
other electric devices; at least one intake port provided in the
mounting portion for introducing into the battery pack cooling air
supplied from a charger; and at least one discharge port provided
in the mounting portion for discharging the cooling air from the
battery pack. The battery pack further includes at least one air
passage connecting the at least one intake port to the at least one
discharge port such that the at least one air passage allows the
cooling air introduced through the at least one intake port to flow
along and/or between the cells and to be discharged through the at
least one discharge port. As the at least one intake port and the
at least one discharge port of the air passage are both provided at
the mounting portion of the battery pack, neither port is exposed
to the exterior of the battery pack when the pack is mounted on a
charger or another electric device. This structure prevents foreign
substances such as water, dust and other various types of debris
from entering the interior of the battery pack, such that rust,
corrosion, or liquid electrolyte leakage of the cells which may
otherwise be caused by ingression of such foreign substances do not
occur.
According to one aspect of the present invention, the mounting
portion includes a substantially rectangular top plate having a
first edge and an opposite second edge, with the at least one
intake port being formed on the top plate in proximity to the first
edge and the at least one discharge port being formed in proximity
to the second edge.
According to another aspect of the present invention, the mounting
portion is contoured to generally correspond to a connecting
portion of the charger and those of the aforementioned other
electric devices such that, when the battery pack is attached to
any of the charger and the aforementioned other electric devices,
the at least one intake port and the at least one discharge port
are unexposed to the exterior environment of the battery pack and
the electric device to which the battery pack is currently
attached.
According to still another aspect of the present invention, when
the battery pack is attached to the charger, a narrow gap is formed
at least along the second edge of the top plate between the
mounting portion of the battery pack and the connecting portion of
the charger so as to facilitate discharge of cooling air from the
at least one discharge port.
According to yet another aspect of the present invention, the
mounting portion includes a step along the second edge where the at
least one discharge port are provided, the step forming the narrow
gap with the connecting portion of the charger.
According to one feature of the present invention, the battery pack
further includes an inner case holding the cells and includes a
plurality of radiators in contact with the cells, and the at least
one air passages are separated from the cells by the inner case. As
the radiator plates, which are brought into contact with the
battery cells, are included on the inner case, the dustproof effect
for the cells is further enhanced without reducing the effect of
cooling the cells.
According to another feature of the present invention, each
radiator is a radiator plate having a plurality of fins protruding
into the air passage and oriented substantially in parallel to the
direction of the flow of cooling air introduced through the at
least intake port.
According to still another feature of the present invention, the
number of fins of each radiator plate increases in the downstream
direction of the cooling airflow.
According to yet another feature of the present invention, the
battery pack includes a pair of slide rails on the mounting portion
and each of the charger and the electric devices includes on the
connecting portion thereof a pair of guide rails which can slidably
engage the slide rails such that the battery pack is attached to
the charger and the electric devices by slide motion.
According to one practice of the present invention, the plurality
of cells are divided into two groups by a longitudinal gap formed
through the inner case, and one of the air passages is at least
partially defined by the gap between the two cell groups.
According to another practice of the present invention, the outer
enclosure includes two inner longitudinal walls and the inner case
includes two outer longitudinal walls which opposes the inner
longitudinal walls across a selected distance so as to at least
partially define two of the air passages between the outer
longitudinal walls and the inner longitudinal walls.
According to still another practice of the present invention, the
electric devices include electric power tools.
According to yet another practice of the present invention, the
charger includes a housing, at least one inlet port provided in the
housing, and at least one exhaust port provided in the housing.
When the battery pack is set on the charger for charging, the at
least one inlet port is located in the portion of the housing
directly opposing the at least one discharge of the battery pack so
as to allow the cooling air discharged out of the discharge ports
of the battery pack to reenter the charger through the inlet port
and to be discharged from the charger through the exhaust port.
The invention is also directed to a battery pack charging system
comprising a battery pack and a charger on which the battery pack
is set for charging. The battery pack includes: an outer enclosure
containing a plurality of battery cells and having a mounting
portion adapted to be removably attached to the charger and other
electric devices; at least one intake port provided in the mounting
portion for introducing cooling air into the battery pack from the
charger; at least one discharge port provided in the mounting
portion for discharging the cooling air from the battery pack; and
at least one air passage connecting the at least one intake port to
the at least one discharge port, with the at least one air passage
allowing the cooling air introduced through the at least one intake
port to flow along and/or between the cells and to be discharged
through the at least one discharge port. The charger includes: a
housing having a connecting portion to which the mounting portion
of the battery pack is attached for charging; a fan contained
within the housing for supplying cooling air to the battery pack;
and at least one airflow passage port formed in the connecting
portion for directing the cooling air supplied from the fan into
the intake port of the battery pack when the battery pack is set on
the charger.
In one embodiment, the charger further includes: at least one inlet
port formed in the portion of the connecting portion opposing the
at least one discharge when the battery pack is set on the charger;
and at least one exhaust port formed in the connecting portion and
placed in pneumatic communication with the at least one inlet port.
In this embodiment, at least part of the cooling air discharged
from the discharge port of the battery pack is allowed to reenter
the charger through the inlet port and to exit from the charger
through the exhaust port.
Other general and more specific objects of the invention will in
part be obvious and will in part be evident from the drawings and
descriptions which follow.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the nature and objects of the present
invention, reference should be made to the following detailed
description and the accompanying drawings, in which:
FIG. 1 is a perspective view of a battery pack in accordance with
the present invention;
FIG. 2 is an exploded perspective view of the battery pack of FIG.
1;
FIG. 3 is a cross-sectional view of the battery pack of FIG. 1;
FIG. 4 is a top plan view of the battery pack of FIG. 1 with the
upper enclosure removed;
FIG. 5 is a top plan view of the battery pack of FIG. 1 with the
upper enclosure and upper holder removed;
FIG. 6 is a perspective view of the inner case of the battery pack
of FIG. 1;
FIG. 7 is a perspective view of a charger for charging the battery
pack of FIG. 1;
FIG. 8 is a plan view of the portion the charger of FIG. 7
accommodating a fan;
FIG. 9 is a cross-sectional view of the portion accommodating the
fan of the charger shown in FIG. 7;
FIG. 10 is a cross-sectional view showing the battery pack of FIG.
1 mounted onto the charger;
FIG. 11A is a partially broken side view showing a power tool's
handle to which the battery pack of FIG. 1 is attached;
FIG. 11B is a bottom plan view of the power tool's handle shown in
FIG. 11A;
FIG. 12 is a cross-sectional view describing how the battery pack
of FIG. 1 is mounted onto the power tool; and
FIG. 13 is a cross-sectional view showing a modification of the
charger shown in FIG. 7 with the battery pack of FIG. 1 mounted
thereon.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred embodiment according to the present invention will be
described hereinafter with reference to the attached drawings.
FIG. 1 is a perspective view of a battery pack 1 in accordance with
the present invention and FIG. 2 is an exploded perspective view of
the battery pack 1. Referring to FIGS. 1 and 2, the battery pack 1
is formed of a double-structured enclosure. The battery pack 1
includes an outer enclosure 2 and inner case 13 which contains a
plurality of cells, with the outer enclosure 2 housing the inner
case 13. In addition, the inner case is formed smaller than the
outer enclosure so as to fit snugly within the outer enclosure. The
outer enclosure 2 includes a lower enclosure 3 generally housing
the inner case 13 and an upper enclosure 4 attached to the lower
enclosure 3 with a plurality of screws which are driven downward
along the height of the lower enclosure 3. Provided on the top
surface of the upper enclosure 4 forming a common mounting portion
to which a charger or a power tool (as will be described later) is
to be attached are a top end 5 and a pair of parallel slide rails 6
extending in a forward direction from the top end 5 (in the
direction opposite the top end 5 from the center of the pack's top
surface). Each slide rail 6 includes an outwardly extending flange
7 along the entire length of the rail 6, thus forming an L-shaped
cross section on a plane which extends orthogonal to the
aforementioned forward direction. Provided at the top end 5 between
and parallel to the pair of parallel slide rails 6 are slits 8.
Provided in the central rear portion of the top end 5 in the upper
enclosure 4 is a rectangular intake port 9 which passes through the
upper enclosure 4. Also provided in the upper enclosure 4 forward
of the top end 5 are discharge ports 11 which open to the external
environment on the boundary of a step 10 formed between the pair of
slide rails 6.
The inner case 13 includes a synthetic resin upper holder 15 and a
lower holder 16 which are affixed to the upper and lower sides,
respectively, of an assembly of twenty cells 14 held therein, the
cells 14 being arranged in four rows of five cells each, with
belt-shaped metal radiator plates 22 provided between the upper
holder 15 and lower holder 16. The upper holder 15 and lower holder
16 are shaped and dimensioned so as to snugly and stably encase the
cells 14. Furthermore, ribs 17 and 18 having edges which conform to
the inner surface of the lower enclosure 3 are provided along the
lower rim of the upper holder 15 and the upper rim of the lower
holder 16, respectively, so as to prevent jarring or rattling of
the cells within the outer enclosure 2 when the inner case 13 is
held therein. Furthermore, in this structure, the cells 14 are
spaced apart and separated into two groups (each of the divided
groups of cells 14 hereinafter is referred to as a "cell group")
held by the upper holder 15 and lower holder 16, with each group
containing half the total number of cells.
In addition, provided at the front and rear ends of the lower
holder 16 are extended portions 19 which protrude from the ribs 18
and are joined to the upper holder 15 such that, as shown in FIGS.
3 and 5, the radiator plates 22 provided on the outer sides of each
of the cell groups are secured by being fitted between the upper
holder 15 and lower holder 16 horizontally along the lengthwise
direction between the ribs 17 and 18 and the cells 14, and
vertically in the shorter direction between the extended portions
19 and cells 14. Similarly, the radiator plates 22 provided between
the cell groups are fitted in the lengthwise direction between the
respective cell groups and partition plates 20 which protrude
between the cell groups from the upper holder 15 and lower holder
16, and in the shorter direction between the extended portions 19
and the cells 14. Furthermore, the surfaces of the radiator plates
22 conform to the projections and recesses of the corresponding
surfaces of each row of cells 14 forming the perimeter of the cell
groups, thus providing equal contact between the surfaces of the
radiator plates 22 and the corresponding outer surface of the cells
therein. Additionally, as shown in FIGS. 2 and 6, four fins 23 are
formed in parallel on the outer surfaces of the radiator plates 22,
beginning at the front end thereof and extending in the rearward
direction. With the exception of the uppermost fin, the three lower
fins 23 are disposed laterally in a step-like arrangement such that
the lengths of the fins increase towards the lowest fin (i.e., the
lowest and highest fins are the longest and the second highest fin
is the shortest) and thus the surface area of the heat-preventing
plates 22 increases with proximity to the front of the battery
pack.
Thus, the cell groups are enclosed in a tightly-packed fashion or
in a substantially sealed manner within the inner case 13, defining
first air passages 24 within the outer enclosure 2, indicated by
the hatched area in FIG. 5, which surrounds the inner case 13
between the ribs 17 and 18 and communicates with a second air
passage 25 (also indicated by the hatched area) penetrating from
the rear to the front of the inner case 13. The forward and rear
portions of the rib 17 are recessed so as to provide communication
between the intake port 9 and the discharge ports 11 of the upper
case 4. Thus, as indicated by the arrows in FIG. 6, the divisions
in the interior of the battery pack 1 are formed such that air
entering from the air intake port 9 is separated into three
airflows which pass through the pack, with the first air passages
24 leading from the intake port 9 to the exterior via the discharge
ports 11 and the second air passage 25, which penetrates the inner
case 13 and extends forward, also exiting to the exterior from the
discharge ports 11. Furthermore, referring to FIG. 4,
vertically-disposed air current adjustment plates 21 are provided
on the front extended section 19 on both sides of the second air
passage 25, causing the flow of air through the first air passages
24 and the flow of air through the second air passage 25 to be
guided to the exhaust ports 11 independently.
Referring again to FIGS. 2 and 3, also provided are a rubber sheet
26 laid between the bottom surface of the inner case 13 and the
inner surface of the lower case 3, sponge sheets 27 laid between
the cell groups and the lower holder 16, and insulating sheets 28.
Furthermore, provided in the rear of the battery pack 1 are a coil
spring 29 and a hook 30 upwardly biased by the coil spring 29. The
hook 30 includes a prong 31 protruding upward through the upper
case 4 when the battery pack 1 is assembled as best shown in FIG.
1.
Additionally, a board 32 is secured with screws to the rear of the
upper surface of the upper case 15 (shown in FIGS. 2, 4 and 6).
Laterally disposed on the upper side of the board 32 are
charge/discharge terminals 33. Lead connector plates 34
electrically connect the charge/discharge terminals 33 with the
exposed electrodes of the terminal cells of the cell groups through
apertures in the upper holder 15. Provided between the
charge/discharge terminals 33 on the board 32 are a temperature
detection terminal 35 and a connector-type data transmission
terminal 36. When the board 32 is housed in the outer enclosure 2,
the charge terminal 33 and the temperature detection terminal 35
are exposed to the exterior environment through the slits 8 formed
in the upper enclosure 4 with the data transmission terminal 36
also exposed in the forward direction. Furthermore, the charge
terminal 33 is formed longer than the temperature detection
terminal 35 so as to achieve the necessary contact pressure when
the battery pack is attached to a power tool.
Furthermore, as shown in FIG. 2, a temperature sensor 37 (for
example, a thermistor) is connected to the temperature detection
terminal 35. The temperature sensor 37 and leads 39 pass downward
through one of through-holes 38 in the front end of the upper
holder 15, and the temperature sensor 37, in attachment to the
bottom holder 16, is inserted between the cells 14 and the extended
portion 19 and affixed to the cells 14. Here, an inclined surface
40 is provided on the inner surface of the extended portion 19 so
as to keep the temperature sensor 37 pressed against the cells 14
upon insertion of the temperature sensor.
FIG. 7 shows a perspective view of a charger 50 onto which the
battery pack 1 is set. The charger 50 includes a main case 51 with
an upper case 52 and a lower case 53, an internal board comprising
a charging circuit, and a connecting portion 54 formed integrally
in the upper side of the upper case 52 to which the battery pack 1
can be removably attached for charging. The connecting portion 54
includes a pair of parallel guide rails 55 which are spaced apart
by a distance greater than the distance between the outermost edges
of the flanges 7 of the slide rails 6 on the battery pack 1. In
addition, an extension 56 projects a short distance inward from the
top surface of each guide rail 55 before extending downward. The
slide rails 6 of the inverted battery pack 1 are inserted between
the guide rails 55 at the rear of the charger 50 (the closer end of
the charger as seen in FIG. 7 will be hereafter referred to as its
rear), so that the guide rails 55 can hold the slide rails 6
therebetween. The battery pack 1 is then moved forward with the
slide rails 6 sliding along the guide rails 55 until stoppers 12
(see FIGS. 1 and 2) at the farthest rear side of the top end 5 of
the battery pack 1 come into abutment with the rear ends of the
guide rails 55.
In addition, the connecting portion 54 of the charger 50 includes a
front portion 57 and a rear portion 58 which is generally located
at a lower plane than the front portion 57 so as to form a
transverse step therebetween that spans the guide rails 55. The
front portion 57 provides a flat surface which abuts and supports
the step 10 of the battery pack 1 when the battery pack 1 is set on
the charger 50.
Furthermore, the surface of the connecting portion 54 is sloped
generally downward to the front end thereof such that the weight of
the battery pack 1 facilitates the battery pack's sliding motion
and stabilizes the battery pack 1 when it is set in place.
Also provided in the rear portion 58 of the connecting portion 54
is a terminal block 59 which includes charging terminals 60, a
temperature detection terminal 61, and a connector-type data
transmission terminal 62. Referring to FIGS. 8 and 9, a cooling fan
63 is provided inside the charger case 51 rearward of the terminal
block 59. The fan 63 is positioned along the longer side of the
charger case 56 and has an upwardly-directed airflow supply port 64
connected in communication with a square airflow passageway 66
which is integrally formed in the upper case 52. The cooling fan 63
additionally includes an intake port 65 which faces rearward. Also
integrally formed in the lower case 53 are air intake ports 67 for
supplying cooling air. Furthermore, a partition wall 68 is provided
in the lower case 63 so as to enclose the portion of the fan 63
lying within the lower case 63, whereas a corresponding
vertically-disposed partition wall 69 is integrally provided in the
upper case 52 so as to conform to the upper surface of the fan 63
other than the portions connecting the airflow supply port 64 and
the airflow passageway 66. In this way, only air from the exterior
of the charger 50 is supplied to the fan 63 through the intake port
65.
During charging of the battery pack 1 so constructed, when the
slide rails 6 of the above mentioned battery pack 1 are placed
between the guide rails 55 of the charger 50 and the battery pack
slid forward until the pack's stoppers 12 come into abutment with
the rear ends of the guide rails 55, charging terminals 60 and a
temperature detection terminal 61 in the terminal block 59 advance
into the slits 8 of the top end 5 of the battery pack and make
electrical contact with the corresponding charge/discharge
terminals 33 and the temperature detection terminal 35,
respectively, while the data transmission terminals 36 and 62 are
also brought into electrical contact, and charging begins. As shown
in FIG. 10, in this state of attachment, the air intake port 9 of
the battery pack 1 is positioned directly above the airflow
passageway 66 of the charger 50, placing both channels in
communication with each other.
During a charge, the heat radiator plates 22 radiate the heat
generated by the cells 14 that is transferred to the radiator
plates 22. The fan 63 simultaneously starts operation at the start
of charging, thus cooling air drawn through the air intake ports 67
is discharged upwards from the airflow supply port 64, and this
airflow, as indicated by the dotted-line arrows, is introduced
through the airflow passageway 66 of the charger 50, after which it
proceeds through the air intake port 9 and on to the interior of
the outer case 2 of the battery pack 1, passes along the first air
passages 24 and the second air passage 25 (the airflow along the
second air passage 25 is shown in FIG. 10), and is discharged to
the exterior from the discharge ports 11. Thus, the radiator plates
22 are cooled by the airflow described above, thereby suppressing
increases in temperature of the cells 14. Additionally, in this
arrangement, as the inverted battery pack faces downward when
attached, the air intake port 9 as well as the discharge ports 11
opens in the downward direction, and so remain unexposed.
According to the present invention, the air intake port 9 and
discharge ports 11 are likewise in this unexposed condition when
the battery pack 1 is attached to a power tool. FIG. 11A is a side
elevation view of a handle 71 of a power tool 70, whereas FIG. 11B
is a bottom plan view of the power tool's handle. The battery pack
is similarly slid for attachment to the handle 71, in which guide
rails 72 for engaging the slide rails 6 of the battery pack 1 are
formed on both sides of the bottom end of the handle 71.
Furthermore, a flange 73 is formed on the underside of each guide
rail 72, with the flanges 73 extending inwardly generally the
entire length of the respective guide rails 72. Provided between
the guide rails 72 is a terminal block 74 with positive and
negative terminal strips 75 that extend in parallel to the guide
rails 72. The electric power tool also includes a recess 76 for
engaging the prong 31 of the hook 30 when the battery pack 1 is
attached to the tool.
Thus, when the slide rails 6 of the battery pack 1 are engaged by
and slid between the guide rails 72 of the handle 71, the pack 1 is
attached to the tool as shown in FIG. 12, in the same manner as in
the attachment of the battery pack to the charger 50. Upon
attachment, the terminal strips 75 of the terminal block 74 are
simultaneously inserted into the slits 8 of the battery pack 1,
making electrical contact with the charge/discharge terminals 33.
In this connected state, as the connection portion of the battery
pack 1 is covered by the handle 71, the air intake port 9 and
exhaust ports 11 are both positioned at the under surface of the
handle 71 rather than being exposed to the exterior
environment.
According to the above embodiment, cooling air is introduced to the
interior of the outer case 2 from the air intake port 9 and
proceeds to flow around and between the cell groups, and is
discharged from the exhaust ports 11 formed in the upper case 4 by
way of the first air passages 24 and the second air passage 25.
Thus, when the battery pack 1 is attached to the charger 50, the
communication between the air intake port 9 as well as the
discharge ports 11 and the charger 50 remains unexposed to the
environment, while when the battery pack 1 is attached to the power
tool 70, the air intake port 9 and discharge ports 11 and the
handle 71 remain unexposed to the environment. Therefore, even as
provided with the air passages 24 and the second air passage 25
through which cooling air passes, this structure enhances the
reliability and life span of the battery pack 1 while alleviating
concerns of problem conditions such as short-circuiting, rusting,
and corrosion.
Furthermore, the battery pack's dual structure, in which the first
air passages 24 and the second air passage 25 are separated from
the cell groups by the inner case 13, which includes the radiator
plates 22 in contact with the cell groups, allows maintenance of
the ideal cooling effect due to the radiator plates 22 and enhanced
dust proof effect on the cell groups. Especially regarding the
radiator plates 22, as the inner surfaces thereof conform to the
protrusions and recesses of the outer surfaces of the cell groups,
this provides even contact with the cells 14, causing heat
generated by the cells 14 to be transferred evenly to the radiator
plates 22, reducing irregularity in the cooling effect on the cells
14. Moreover, the fins 23 that are provided on the outer surfaces
of the radiator plates 22 are formed such that the number of fins
increases as the flow progresses downward. So even as the
temperature of the air flowing along the radiator plates 22
increases due to heat exchanged by the radiator plates 22, the
increased number of fins 23 results in a greater cooling capacity
to counteract this greater amount of heat, thus securing cooling
effect of the cells 14 by the radiator plates 22 along the entire
length of the radiator plates 22.
Furthermore, the design is not limited to the number and shape of
air intake port 9 and exhaust ports 11 mentioned above; rather, the
numbers of fins may be increased or decreased and the designed may
be changed as desired. Additionally, whereas a sliding method is
used in the above embodiment for attachment of the battery pack to
a charger or power tool, according to the present invention methods
wherein a portion of a battery pack is inserted into the charger or
power tool may be employed.
Further regarding formation of the air passages, the cells
alternatively may be so configured as to be separated into three or
more cell groups or blocks, thereby increasing the number of air
passages; furthermore, there is no obstacle to having the air
passages oriented along groups of cells from left to right, or vice
versa, rather than only front to back. Naturally, another structure
of an inner case is possible in which separate air passages are
formed merely by partition walls within the outer case. In this
modification, the radiator plates are disposed in the partition
walls so as to be brought into contact with portions of the cells,
without the use of a fully double-structured case which includes an
inner case for holding the cells therein.
The charger may also be changed as shown in FIG. 13. In this
particular modification, as shown by the dotted/dashed line arrows,
when the battery pack 1 is in attachment with the upper case 52,
air inlet ports 80 are disposed directly below the discharge ports
11, and air exhaust ports 81 are disposed at the top, bottom, and
sides of the main case 51, thus causing the airflow to be
discharged from the air inlet ports 80 and then again from the
exhaust ports 81 provided in the charger 50, thus also cooling the
board 82 and other structures of the charger 50, further enhancing
protection of the charging circuitry. In conventional battery
chargers, the charging circuitry is protected by a reduction in the
charging current, which results in longer charging times. However,
the relationship between temperature and charging time also means
that cooling allows the charging current to be similarly increased,
thus shortening the charging time.
Equivalents
It will thus be seen that the present invention efficiently attains
the objects set forth above, among those made apparent from the
preceding description. As other elements may be modified, altered,
and changed without departing from the scope or spirit of the
essential characteristics of the present invention, it is to be
understood that the above embodiments are only an illustration and
not restrictive in any sense. The scope or spirit of the present
invention is limited only by the terms of the appended claims.
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