U.S. patent application number 12/978803 was filed with the patent office on 2011-06-30 for power source apparatus having bus-bars.
Invention is credited to Shingo OCHI.
Application Number | 20110159350 12/978803 |
Document ID | / |
Family ID | 43929196 |
Filed Date | 2011-06-30 |
United States Patent
Application |
20110159350 |
Kind Code |
A1 |
OCHI; Shingo |
June 30, 2011 |
POWER SOURCE APPARATUS HAVING BUS-BARS
Abstract
The power source apparatus is provided with batteries having
positive and negative electrode regions, parallel blocks with
batteries stacked together and electrically connected in parallel,
multiple parallel-series connected blocks with the parallel blocks
electrically connected in series, and bus-bars having a plurality
of insertion holes to insert the positive and negative electrode
regions and electrically connect the batteries. Batteries in a
parallel block are stacked together lining-up positive electrode
regions on one side and negative electrode regions on the other
side. Parallel blocks in a multiple parallel-series connected block
are stacked reversing the orientation of each block added to the
stack. The bus-bars are integrated pieces that can electrically
connect the batteries in a parallel block in parallel as well as
electrically connect the parallel blocks in series.
Inventors: |
OCHI; Shingo; (Takasago-shi,
JP) |
Family ID: |
43929196 |
Appl. No.: |
12/978803 |
Filed: |
December 27, 2010 |
Current U.S.
Class: |
429/159 |
Current CPC
Class: |
Y02P 70/50 20151101;
Y02T 10/70 20130101; B60L 2210/40 20130101; B60L 2270/145 20130101;
Y02T 10/72 20130101; B60L 58/21 20190201; H01M 10/647 20150401;
B60L 58/18 20190201; B60L 50/62 20190201; H01M 50/20 20210101; Y02T
10/64 20130101; B60L 2240/441 20130101; B60L 2210/30 20130101; H01M
50/543 20210101; B60L 50/66 20190201; H01M 50/502 20210101; B60L
58/26 20190201; Y02T 10/62 20130101; B60L 2240/36 20130101; B60L
2240/545 20130101; H01M 10/425 20130101; H01M 10/482 20130101; H01M
10/613 20150401; Y02T 10/7072 20130101; H01M 10/625 20150401; Y02E
60/10 20130101; B60L 3/0046 20130101; B60L 2240/421 20130101; H01M
10/052 20130101; H01M 10/6563 20150401; B60L 50/64 20190201 |
Class at
Publication: |
429/159 |
International
Class: |
H01M 10/02 20060101
H01M010/02; H01M 6/42 20060101 H01M006/42 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2009 |
JP |
2009-296705 |
Claims
1. A power source apparatus comprising: batteries having positive
and negative electrode regions; parallel blocks with the batteries
stacked together and electrically connected in parallel; multiple
parallel-series connected blocks with the parallel blocks
electrically connected in series; and bus-bars having a plurality
of insertion holes to insert the positive and negative electrode
regions and electrically connect the batteries, wherein batteries
in a parallel block are stacked together lining-up positive
electrode regions on one side and negative electrode regions on the
other side of the parallel block, parallel blocks in a multiple
parallel-series connected block are stacked reversing the
orientation of each parallel block added to the stack, and the
bus-bars are integrated pieces that electrically connect the
batteries in a parallel block in parallel as well as electrically
connect the parallel blocks in series.
2. The power source apparatus as cited in claim 1 wherein the size
of the insertion holes in a bus-bar with a plurality of insertion
holes increases gradually in the battery stacking direction.
3. The power source apparatus as cited in claim 2 wherein the
insertion hole at one end of a bus-bar is the smallest and
insertion hole size increases gradually towards the other end of
the bus-bar.
4. The power source apparatus as cited in claim 2 wherein the
insertion hole at the center part of a bus-bar is the smallest and
insertion hole size increases gradually towards both ends of the
bus-bar.
5. The power source apparatus as cited in claim 2 provided both
with bus-bars having the smallest insertion hole at one end with
insertion hole size increasing gradually towards the other end, and
with bus-bars having the smallest insertion hole at the center part
with insertion hole size increasing gradually towards both
ends.
6. The power source apparatus as cited in claim 1 wherein the
high-current section of a bus-bar is made thicker than other parts
of the bus-bar.
7. The power source apparatus as cited in claim 1 wherein the
high-current section of a bus-bar is made with more surface area
than other parts of the bus-bar.
8. The power source apparatus as cited in claim 1 wherein a bus-bar
is made entirely of a single material.
9. The power source apparatus as cited in claim 1 wherein a bus-bar
is formed as a single integrated piece using clad-material made of
dissimilar materials.
10. The power source apparatus as cited in claim 2 wherein a
detection line to detect the battery state is connected at the
smallest insertion hole in a bus-bar.
11. The power source apparatus as cited in claim 2 wherein
insertion hole size for a bus-bar with a plurality of insertion
holes increases by 0.1 mm for each hole.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a power source apparatus
with a plurality of batteries stacked together, and primarily
relates to a battery system used as a power source for a motor that
drives a vehicle such as a hybrid car (hybrid vehicle; HV, hybrid
electric vehicle; HEV), plug-in hybrid car (plug-in hybrid electric
vehicle; PHEV), or electric automobile (electric vehicle; EV).
[0003] 2. Description of the Related Art
[0004] A high-current, high-output voltage battery system used to
power a motor that drives a vehicle such as a hybrid car, plug-in
hybrid, or electric automobile has a plurality of batteries stacked
together and electrically connected to deliver high output.
Adjacent battery electrode terminals are connected via bus-bars,
and current flows through those bus-bars for electrical
connection.
[0005] Methods of electrically connecting a plurality of stacked
batteries together include series-connection and
parallel-connection. Further, those two methods combine as
parallel-connected groups of multiple batteries connected in series
(multiple series-parallel) and series-connected groups of multiple
batteries connected in parallel (multiple parallel-series). When
connecting a plurality of batteries, the connection method should
be selected according to the performance required from the
batteries employed.
[0006] If we assume the use of the same number of batteries with
the same performance, series-connection results in higher battery
voltage than parallel-connection and is primarily suitable for a
hybrid car that demands high-power. In contrast,
parallel-connection results in higher battery capacity than
series-connection and is primarily suitable for an electric
automobile that can be driven a long distance with a single battery
charge.
[0007] Battery capability required for a vehicle such as a plug-in
hybrid is between that required for a hybrid car and an electric
automobile. Accordingly, series and parallel combinations are used
and batteries are connected in multiple series-parallel
(parallel-connected groups of multiple batteries connected in
series) or multiple parallel-series (series-connected groups of
multiple batteries connected in parallel).
[0008] Compared with multiple series-parallel connection, multiple
parallel-series connection can detect the state of all the
batteries with a limited number of battery state detection lines.
Further, since voltage variation between parallel-connected
batteries is low and since the detection circuitry is not complex,
battery and safety-related control can be simplified in a multiple
parallel-series connected system. In addition, the number of
bus-bars needed to connect individual batteries together is small
allowing the number of component parts to be reduced. Consequently,
the overall battery structure can be made compact allowing
advantageous use in vehicle applications demanding reduced size.
Based on these considerations, when there is a choice between
multiple series-parallel connection and multiple parallel-series
connection, multiple parallel-series connection (series-connected
groups of multiple batteries connected in parallel) is often
selected.
[0009] A bus-bar, which is described below, has been previously
developed as a connecting piece to electrically connect battery
electrodes together. A rectangular battery has circular cylindrical
positive and negative electrode terminals protruding from both ends
of its top surface. A bus-bar straddles adjacent rectangular
batteries to connect positive and negative electrode terminals
(refer to Japanese Laid-Open Patent Publication 2008-91183).
[0010] The bus-bar has a shape such as rectangular or elliptical
with two identically sized circular holes, and electrode terminals
insert through those holes. The electrode terminals that protrude
from a rectangular battery are threaded to accept nut attachment.
As shown in FIG. 1 of JP 2008-91183, nuts are threaded onto the
electrode terminals on top of a bus-bar and tightened to attach the
bus-bar to the electrode terminals. A plurality of rectangular
batteries is electrically connected in series by the bus-bars.
[0011] To connect batteries in a multiple parallel-series
configuration consistent with techniques described for
series-connection in JP 2008-91183, the following method can be
devised. For example, to connect twenty batteries in four
series-connected groups of five batteries connected in parallel
(five parallel-four series), first groups of five batteries are
stacked together with like-polarity electrode terminals lined-up on
each side to form four blocks of batteries. Next, the five positive
electrode terminals of each block are connected together with a
bus-bar provided with five holes. Similarly, the five negative
electrode terminals of each block are connected together with a
bus-bar provided with five holes to connect the batteries in each
block in parallel. At the positions where these four blocks are
joined in series, new connecting hardware must be added
unfortunately increasing the number of component parts. If the
number of component parts is increased, the system has the drawback
that assembly becomes more complex, contact resistance problems can
develop, and battery output can degrade as a result.
[0012] The present invention was developed to resolve the problems
described above. Thus, it is an object of the present invention to
provide a power source apparatus that can connect battery electrode
terminals together in a simple manner for multiple parallel-series
connection (series-connected groups of multiple batteries connected
in parallel) and improve battery output as well.
SUMMARY OF THE INVENTION
[0013] The power source apparatus for the first aspect of the
present invention is provided with batteries having positive and
negative electrode regions, parallel blocks with batteries stacked
together and electrically connected in parallel, multiple
parallel-series connected blocks with the parallel blocks
electrically connected in series, and bus-bars having a plurality
of insertion holes to insert the positive and negative electrode
regions and electrically connect the batteries. Batteries in a
parallel block are stacked together lining-up positive electrode
regions on one side and negative electrode regions on the other
side of the parallel block. Parallel blocks in a multiple
parallel-series connected block are stacked by sequentially
reversing the orientation of each block added to the stack. The
bus-bars are integrated pieces that can electrically connect the
batteries in a parallel block in parallel as well as electrically
connect the parallel blocks in series.
[0014] In the power source apparatus for the second aspect of the
present invention, the size of the insertion holes in a bus-bar
with a plurality of insertion holes can increase gradually in the
battery stacking direction.
[0015] In the power source apparatus for the third aspect of the
present invention, the insertion hole at one end of a bus-bar can
be the smallest and insertion hole size can increase gradually
towards the other end of the bus-bar.
[0016] In the power source apparatus for the fourth aspect of the
present invention, the insertion hole at the center of a bus-bar
can be the smallest and insertion hole size can increase gradually
towards both ends of the bus-bar.
[0017] The power source apparatus for the fifth aspect of the
present invention can be provided with bus-bars both having the
smallest insertion hole at one end with insertion hole size
increasing gradually towards the other end, and having the smallest
insertion hole at the center with insertion hole size increasing
gradually towards both ends.
[0018] In the power source apparatus for the sixth aspect of the
present invention, the high-current section of a bus-bar can be
made thicker than other parts of the bus-bar.
[0019] In the power source apparatus for the seventh aspect of the
present invention, the high-current section of a bus-bar can be
made with more surface area than other parts of the bus-bar.
[0020] In the power source apparatus for the eighth aspect of the
present invention, a bus-bar can be made entirely of a single
material.
[0021] In the power source apparatus for the ninth aspect of the
present invention, a bus-bar can be formed as a single-piece using
clad-material made of dissimilar materials.
[0022] In the power source apparatus for the tenth aspect of the
present invention, a detection line to detect the battery state can
be connected at the smallest insertion hole in a bus-bar.
[0023] In the power source apparatus for the eleventh aspect of the
present invention, insertion hole size for a bus-bar with a
plurality of insertion holes can increase by 0.1 mm for each
hole.
[0024] As a result of the first aspect of the present invention,
bus-bars used in a multiple parallel-series block have an
integrated structure that can electrically connect individual
batteries in a parallel block in parallel and can also electrically
connect individual parallel blocks in series. Therefore, the number
of bus-bars needed to connect the batteries together can be
reduced, the number of component parts can be reduced, and the
number of manufacturing and assembly steps can be reduced.
[0025] Consequently, the overall battery structure can be made
compact, and the system is advantageously suited for automotive
applications that demand small size to fit in a limited space.
[0026] As a result of the second aspect of the present invention,
the size of the insertion holes provided in a bus-bar having a
plurality of insertion holes and used in a multiple parallel-series
block can increase gradually in the battery stacking direction.
Consequently, the bus-bars are not mechanically stressed and can be
easily connected while preventing position shift between the
insertion holes and battery electrode regions. Further, since the
contact surface area between the batteries and bus-bar connecting
regions can be increased to reduce contact resistance and increase
the current-carrying capacity from the batteries to the bus-bars, a
large increase in output can be attained.
[0027] In addition, bus-bar overall insertion hole area is reduced
allowing the bus-bar electrical resistance to be reduced and the
output to be greatly increased. Furthermore, when bus-bar
electrical resistance is reduced, heat generation from bus-bars
carrying high-currents can be prevented.
[0028] As a result of the third aspect of the present invention,
the insertion hole at one end of a bus-bar is smallest and
insertion hole size increases gradually towards the other end of
the bus-bar. In a parallel block, if the smallest insertion hole is
in the high current flow region of the bus-bar, bus-bar electrical
resistance can be reduced. This allows bus-bar heat generation to
be held to a minimum and output to be increased. Further, as the
amount of current flow decreases along the bus-bar, the electrical
resistance gradually increases (because insertion hole size
gradually increases). Consequently, uniform thermal distribution
can be expected throughout the bus-bar.
[0029] As a result of the fourth aspect of the present invention,
the insertion hole at the center of a bus-bar is smallest and
insertion hole size increases gradually towards both ends of the
bus-bar. This allows overall bus-bar insertion hole area to be
reduced compared to a bus-bar with the smallest insertion hole at
one end. Consequently, since the contact surface area between the
batteries and bus-bar connecting regions can be increased, output
can be further increased.
[0030] As a result of the fifth aspect of the present invention,
bus-bars are provided both with insertion hole size increasing
gradually from one end to the other and with insertion hole size
increasing gradually from the center towards both ends.
Consequently, this allows optimal bus-bar allocation throughout the
system to maximize output for any battery configuration.
[0031] As a result of the sixth aspect of the present invention,
the high-current section of a bus-bar is made thicker than other
parts, and the electrical resistance of the bus-bar itself can be
reduced.
[0032] As a result of the seventh aspect of the present invention,
the high-current section of a bus-bar has more surface area than
other parts, and the electrical resistance of the bus-bar itself
can be reduced. Furthermore, by increasing the surface area, heat
generated by the bus-bar can be more easily dissipated.
[0033] As a result of the eighth aspect of the present invention, a
bus-bar is made entirely of a single material to simplify
manufacturing and gain advantage from the viewpoint of component
part commonality.
[0034] As a result of the ninth aspect of the present invention,
clad-material made of dissimilar materials is used in an integrated
single-piece bus-bar that connects parallel blocks in series. When
the bus-bar is connected to positive and negative electrode regions
made of different materials, the positive and negative electrode
regions can be connected to bus-bar regions of like-material.
Consequently, galvanic corrosion can be prevented, and the bus-bar
and batteries can remain connected in a stable, low-resistance
manner over a long time period.
[0035] As a result of the tenth aspect of the present invention, a
battery state detection line is connected at the smallest insertion
hole in a bus-bar. Accordingly, the detection line can be reliably
connected to the electrode region in a low-resistance manner, and
the state of the batteries can be accurately detected.
[0036] As a result of the eleventh aspect of the present invention,
bus-bar insertion hole size increases by 0.1 mm for each hole
allowing variation in parameters such as the contact surface area
to be minimized.
[0037] The above and further objects of the present invention as
well as the features thereof will become more apparent from the
following detailed description to be made in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIG. 1 is a schematic of a hybrid vehicle (vehicle body
labeled HV) equipped with the power source apparatus of the present
invention;
[0039] FIG. 2 is a schematic of a electric vehicle (vehicle body
labeled EV) equipped with the power source apparatus of the present
invention;
[0040] FIG. 3 is a perspective view of the exterior of the battery
holding case of the power source apparatus of the present
invention;
[0041] FIG. 4 is a top view showing the internal structure of the
battery holding case of the power source apparatus of the present
invention;
[0042] FIG. 5 is a perspective view of the exterior of a five
parallel-four series connected (four series-connected groups of
five batteries connected in parallel) battery block for the power
source apparatus of the present invention;
[0043] FIG. 6 is an exploded perspective view of the exterior of
the five parallel-four series battery block for the power source
apparatus of the present invention;
[0044] FIG. 7 is an exploded perspective view of the exterior of
rectangular batteries and separators stacked for the first
embodiment;
[0045] FIG. 8 is a top view of the first bus-bar for the first
embodiment;
[0046] FIG. 9 is a cross-section view through the line E-E in FIG.
8;
[0047] FIG. 10 is a cross-section view through the line C-C in FIG.
8;
[0048] FIG. 11 is a cross-section view through the line A-A in FIG.
8;
[0049] FIG. 12 is a side view of the first bus-bar for the first
embodiment;
[0050] FIG. 13 is a top view of the second bus-bar for the first
embodiment;
[0051] FIG. 14 is a side view of the second bus-bar for the first
embodiment;
[0052] FIG. 15 is a top view of the third bus-bar for the first
embodiment; and
[0053] FIG. 16 is a side view of the third bus-bar for the first
embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0054] The following describes in detail embodiments of the present
invention based on FIGS. 1-16.
[0055] Examples of the power source apparatus 1 installed on-board
a vehicle are described based on FIGS. 1 and 2.
[0056] FIG. 1 shows an example of the power source apparatus 1
installed on-board a hybrid vehicle (vehicle body labeled HV)
having a primary engine 2 and motor 3 used in parallel to deliver
power to the wheels and drive the vehicle. Since two power sources
operate in parallel to drive the wheels of the vehicle in this
figure, the drive-train is called parallel hybrid.
[0057] The vehicle HV with the power source apparatus 1 on-board is
provided with an engine 2 and motor 3 that drive the vehicle HV, a
power source apparatus 1 equipped with a battery 4 that supplies
electrical power to the motor 3, and a generator 5 that charges
rectangular batteries 21 in the power source apparatus 1 battery 4.
The power source apparatus 1 is connected to the motor 3 and the
generator 5 through a DC/AC inverter 6.
[0058] The hybrid vehicle HV is driven by the motor 3 and engine 2
operating together while charting and discharging the power source
apparatus 1 battery 4. The engine 2 primarily drives the vehicle,
and under given conditions, charges the rectangular batteries 21 in
the power source apparatus 1 battery 4. The motor 3 is operated by
power supplied from the power source apparatus 1 and operates
together with the engine 2 to assist the engine 2 in high load
situations such as departure and acceleration. In addition, the
motor 3 provides driving power at low speeds, the engine 2 provides
driving power at high speeds, and division of the load allows
energy efficiency to be increased. Further, the motor 3 operates as
a generator 5 during vehicle braking to charge the rectangular
batteries 21 in the power source apparatus 1 battery 4.
[0059] Besides the parallel hybrid system described above, a hybrid
vehicle can also be configured as a series hybrid system or a
power-split hybrid system. A series hybrid is driven only by a
motor, which is the single source of driving power to the wheels,
and an engine is provided to generate electric power that is
supplied to the motor. A power-split hybrid combines a separate
battery-charging generator with the parallel hybrid system
described above to control engine load more precisely and improve
energy efficiency compared to the parallel system. The power-split
hybrid system is provided with a power-split mechanism that divides
the engine's mechanical power between driving the vehicle and
operating the generator. The vehicle is efficiently run while
controlling the rotational speed (revolutions per minute; RPM) of
the generator and the motor using the power-split mechanism. A
power-split hybrid is also called a series-parallel hybrid.
[0060] Next, FIG. 2 shows an example of the power source apparatus
1 installed on-board an electric vehicle (vehicle body labeled EV)
driven only by an electric motor 3. The vehicle EV with the power
source apparatus 1 on-board is provided with a driving motor 3 that
drives the vehicle EV, a power source apparatus 1 equipped with a
battery 4 that supplies electrical power to the motor 3, and a
generator 5 that charges rectangular batteries 21 in the power
source apparatus 1 battery 4. The power source apparatus 1 is
connected to the motor 3 and the generator 5 through a DC/AC
inverter 6. The vehicle EV is driven only by the motor 3 while
charging and discharging the power source apparatus 1 battery 4.
Electrical power is supplied from the power source apparatus 1 to
operate the motor 3. The generator 5 is run by energy produced
during regenerative braking to charge the previously mentioned
rectangular batteries 21 in the power source apparatus 1 battery
4.
[0061] The first embodiment of the power source apparatus 1 of the
present invention, which is installed on-board the vehicles
mentioned above, is described in detail based on FIGS. 3-14.
However, the vehicle installed with the power source apparatus 1 of
the present invention is not limited to the vehicles described
above, and can also be a vehicle such as a plug-in hybrid electric
vehicle (PHEV).
[0062] FIG. 3 shows a perspective view of the exterior of the
battery holding case 10 of the power source apparatus 1 of the
present invention, which is installed in applications such as
on-board a vehicle. The power source apparatus 1 battery holding
case 10 houses a battery 4 made up of five parallel-four series
battery blocks 20, each of which is four series-connected groups of
five batteries connected in parallel as described later. The
battery holding case 10 is an enclosure made up of an upper case 11
and a lower case 12 that are formed by working metal material such
as aluminum. The battery holding case 10 protects a plurality of
five parallel-four series battery blocks 20 from external impact
and pressure forces. The upper case 11 covers a plurality of five
parallel-four series battery blocks 20 disposed on the lower case
12.
[0063] Further, as shown in FIG. 3, an intake opening 15 is
provided in the middle of both end-walls 13 of the upper case 11
and both end-walls 14 of the lower case 12. Cooling ventilation
flows into the intake openings 15 to initiate rectangular battery
21 cooling. Exhaust openings 16 are provided on both sides of the
central intake openings 15. Cooling ventilation flows out the
exhaust openings 16 after cooling the rectangular batteries 21.
Cooling ventilation flows into the battery holding case 10 from the
intake openings and after circulating through the inside of the
battery holding case 10 is discharged to the outside from the
exhaust openings 16.
[0064] FIG. 4 shows the lower case 12 of the battery holding case
10 of FIG. 3 viewed from above with the upper case 11 removed, and
is a top view that shows the internal structure of the battery
holding case 10. Five parallel-four series battery blocks 20 (four
series-connected groups of five batteries connected in parallel)
are arranged in the lower case 12 in two rows and two columns. The
series-connection of those five parallel-four series battery blocks
20 is the battery 4. Accordingly, the power source apparatus 1
battery 4 can be made high output with high capacity, and that
battery 4 can supply power to the motor 3 that drives the
vehicle.
[0065] FIG. 5 is a perspective view of the exterior of one of the
four five parallel-four series battery blocks 20 shown in FIG. 4.
FIG. 6 shows an exploded perspective view of the exterior of the
five parallel-four series battery block 20 shown in FIG. 5. The
following describes in detail the five parallel-four series battery
block (4 series-connected groups of 5 batteries connected in
parallel).
[0066] A five parallel-four series battery block 20 is a stack of
twenty rectangular batteries 21. As shown in FIG. 7, each
rectangular battery 21 has a rectangular outline with narrow sides
22. The external case of a rectangular battery 21 is made of metal
and rectangular batteries 21 are stacked together with insulation.
Further, the rectangular batteries 21 are lithium ion rechargeable
batteries, which have a high capacity for a given weight and volume
compared to battery cells such as nickel hydride batteries.
Consequently, these lithium ion rectangular batteries 21 are well
suited for use in a battery 4 that supplies power to a motor 3 for
applications such as in a vehicle where small size and light weight
are required.
[0067] As shown in FIG. 7, the upper surface 23 of a rectangular
battery 21 has electrode regions 24 at each end that are made up of
positive and negative electrode terminal surfaces 24A, 24B and
positive and negative electrode terminals 24a, 24b. Part of each
electrode terminal surface 24A, 24B is inclined to form an acute
angle between the electrode terminal surface 24A, 24B and the upper
surface 23 of the rectangular battery 21. The electrode terminals
24a, 24b are made in the shape of circular cylinders that project
outward in a direction perpendicular to the inclined part of the
electrode terminal surfaces 24A, 24B. Electrode terminals 24a, 24b
are threaded to allow nuts to be screwed on and tightened. In
addition, the upper surface 23 of a rectangular battery 21 is
provided with an opening to add electrolyte and a gas discharge
valve. As shown in FIG. 7, rectangular battery 21 stacking is
accomplished with intervening separators 25.
[0068] A separator 25 is made by forming insulating material such
as resin in a size essentially equal to that of a rectangular
battery 21. Separators 25 cover the surfaces of stacked rectangular
batteries 21 to insulate each individual rectangular battery 21,
and adjacent separators 25 come in mutual contact. The separators
25 are formed with shapes that prevent position shift in the
bus-bars 30, 40, 42 described later. The separators 25 also serve
to align the positions of the rectangular batteries 21 and enable
the rectangular batteries 21 to be stacked with a
constant-interval. The separators 25 are provided with passageways
such as cooling channels (not illustrated) to cool the rectangular
batteries 21.
[0069] Four types of separators 25 are used In the first
embodiment. First, the separator 25 positioned towards the rear
(right) in FIG. 7 is a first separator 25A and has an insulating
plate 26. The insulating plate 26 is provided at only one end of
the upper surface of the first separator 25A. By providing an
insulating plate 26, adjacent bus-bars 30, 40, 42 can be insulated
from one another and bus-bar contact and short circuit due to
conditions such as vibration can be prevented. The other end of the
upper surface of the first separator 25A is provided with a
projecting piece 27.
[0070] Next, the separator 25 positioned towards the front (left)
in FIG. 7 is a second separator 25B, and the upper surface of the
second separator 25B is provided with projecting pieces 27 at both
ends. A second separator 25B with a projecting piece 27 provided at
only one end is a third separator 25C. A separator 25 with
insulating plates 26 at both ends of the upper surface is a fourth
separator 25D and is disposed next to an endplate 51 described
later. Fourth separators 25D are disposed at both ends of a five
parallel-four series battery block 20.
[0071] Second separators 25B and third separators 25C are arranged
to fit with the shapes of the bus-bars 30, 40, 42 and align the
bus-bars 30, 40, 42 in positions allowing them to be solidly
connected. Consequently, stress on parts such as the electrode
terminals 24a, 24b and bus-bars 30, 40, 42 due to conditions such
as vibration can be reduced. Further, since the nuts 50 used to
attach the bus-bars 30, 40, 42 are less likely to loosen, short
circuits inside the battery 4 can be prevented, and this has the
effect that battery 4 performance can be maximized over the
long-term.
[0072] A five parallel-four series battery block 20 is made up of
four parallel blocks 28. A parallel block 28 is five rectangular
batteries 21 stacked together with intervening separators 25 and
electrically connected in parallel. The parallel block 28 has
rectangular batteries 21 stacked in a manner that lines-up positive
electrode terminals 24a on one side of the upper surface of the
parallel block 28 and lines-up negative electrode terminals 24b on
the other side. The positive electrode terminals 24a of the five
rectangular battery 21 stack are connected with a first bus-bar 30,
and the negative electrode terminals 24b are connected with a
second bus-bar 40 to achieve parallel electrical connection. The
first bus-bar 30 and second bus-bar 40 are described in detail
later.
[0073] As shown in FIGS. 5 and 6, a five parallel-four series
battery block 20 is made up of four parallel blocks 28 with each
parallel block 28 rotated laterally 180.degree. with respect to the
previously stacked parallel block 28 to connect the four parallel
blocks 28 in series. The upper surface of the five parallel-four
series battery block 20 has parallel blocks 28 stacked with a
180.degree. (2-fold) rotational symmetry relation maintained at the
intersection of each pair of parallel blocks 28. Specifically, two
adjacent parallel blocks 28 are stacked in a manner that lines-up
five positive electrode terminals 24a and five negative electrode
terminals 24b in a single line. At locations that electrically
connect four parallel blocks 28 in series by connecting a line of
five positive electrode terminals 24a and five negative electrode
terminals 24b, that total of ten positive and negative electrode
terminals 24a, 24b are all connected together by a third bus-bar
42.
[0074] The following describes the first bus-bar 30, the second
bus-bar 40, and the third bus-bar 42 based on FIGS. 5-16.
[0075] First, FIG. 8 shows a top view of the first bus-bar 30, and
cross-sections through the lines E-E, C-C, and A-A are shown in
FIGS. 9-11. The first bus-bar 30 is the bus-bar disposed at the
rear-left side of FIG. 6. FIG. 12 shows a side view of the first
bus-bar 30 as viewed from above the center of the upper surface 23
of a rectangular battery 21.
[0076] The first bus-bar 30 shown in FIG. 8 is made from a metal
such as pure copper, has a thin-plate basically rectangular shape,
and is press-formed into a shape that conforms to the inclined
parts of the electrode terminal surfaces 24A, 24B and the
separators 25 that cover the rectangular batteries 21. Accordingly,
the first bus-bar 30 is formed with an inclined region 31, a bent
region 32, and a planar region 33. By providing a bent region 32,
the position of the first bus-bar 30 can be aligned by the
separators 25. The inclined region 31 is provided with five
insertion holes 36 in a straight-line arrangement to accept
insertion of five positive electrode terminals 24a. Further, the
surface area of the inclined region 31 around each insertion hole
36 is increased compared to locations with no insertion hole 36 to
increase the cross-sectional area of the first bus-bar 30 in the
vicinity of each insertion hole 36.
[0077] FIG. 9 is a cross-section through the line E-E where no
insertion hole 36 is opened through the first bus-bar 30. In
contrast, FIG. 10 is a cross-section through the line C-C where an
insertion hole 36 is established. As described above, by locally
varying the surface area of the inclined region 31 depending on
whether or not an insertion hole 36 is present, the cross-sectional
areas shown in FIGS. 9 and 10 can be made approximately equal. This
allows the electrical resistance of the first bus-bar 30 itself to
be made more uniform. As a result, current can flow smoothly
(current density can be made more uniform) through the first
bus-bar 30, battery 4 output can be increased, and battery 4
performance can be maximized.
[0078] The insertion hole 36 closest to one end 34 of the first
bus-bar 30 is the first insertion hole 36a and is made with a
diameter of 5.1 mm. The size of the first insertion hole 36a is set
to a size that is only slightly larger than the inserted positive
electrode terminal 24a. The diameter of the other insertion holes
36 increases at each hole by 0.1 mm from the reference size of the
first insertion hole 36a at one end 34 of the first bus-bar 30
towards the other end 35. Specifically, in order from one end 34 of
the first bus-bar 30, a first insertion hole 36a with a diameter of
5.1 mm, a second insertion hole 36b with a diameter of 5.2 mm, a
third insertion hole 36c with a diameter of 5.3 mm, a fourth
insertion hole 36d with a diameter of 5.4 mm, and a fifth insertion
hole 36e with a diameter of 5.5 mm are established.
[0079] Since pure copper used in the first bus-bar 30 has low
electrical resistance compared to other metals such as common
grades of copper, the electrical resistance of the first bus-bar 30
itself can be reduced. Further, by changing the hole diameter at
each insertion hole 36, overall insertion hole 36 area can be
reduced compared to prior art with the same hole diameter at all
insertion holes. If insertion hole 36 area is reduced (by reducing
hole diameter overall), the contact surface area increases between
positive electrode terminal surfaces 24A and the first bus-bar 30
to reduce contact resistance and increase the amount of current
flow from the rectangular batteries 21 to the first bus-bar 30.
This increases battery 4 output and can yield a high capacity
battery 4.
[0080] By gradually increasing insertion hole diameter while
reducing hole diameter overall, positive electrode terminal 24a
position shift due to expansion of the stacked rectangular
batteries 21 or due to variation in the rectangular batteries 21 or
in the assembly process can be tolerated. Consequently, positive
electrode terminals 24a can be easily inserted in the first bus-bar
30 and stress is not applied to the first bus-bar 30 as a result of
impact forces or vibration.
[0081] In the first embodiment, five rectangular batteries 21 are
connected in parallel, and compared to prior art with the same
number of rectangular batteries connected in series, a maximum of
five times the current flows in the first bus-bar 30. Accordingly,
the first bus-bar 30 does not simply join together prior art
bus-bars used for series-connection, but rather to increase
current-carrying capability, the surface area, thickness, and
cross-sectional area of the first bus-bar 30 is increased compared
to the prior art bus-bars. The part of the first bus-bar 30 where
surface area is mainly increased is in the planar region 33. The
planar region 33 faces the upper surfaces of the separators 25.
[0082] First bus-bar 30 surface area is increased by providing the
planar region 33 and cross-sectional area is increased by making
the first bus-bar 30 . thicker. Those features interact allowing
multiplicative reduction in the electrical resistance of the body
of the bus-bar, and allowing the current-carrying capability to be
increased in the first bus-bar 30, which carries high currents as a
result of parallel connection. Further, as a result of electrical
resistance decrease in the body of the first bus-bar 30, heat
generation caused by high current flow can be suppressed and
adverse thermal effects on the rectangular batteries 21 and
separators 25 can be prevented. In addition, by increasing first
bus-bar 30 surface area, heat generated can be easily dissipated to
prevent overheating.
[0083] The first bus-bar 30 planar region 33 shown in FIG. 8 is
provided with a positive electrode rod 37, which is disposed at the
end 35 of the first bus-bar 30 planar region 33 and connects to the
DC/AC inverter 6. The positive electrode rod 37 is formed in a
circular cylindrical shape that projects vertically from the planar
region 33. Further, the surface area of the planar region 33 around
the positive electrode rod 37 is increased by making the planar
region 33 wider than where there is no positive electrode rod 37.
This increases the cross-sectional area of the first bus-bar 30.
FIG. 11 is a cross-section view through the line A-A where the
positive electrode rod 37 is established.
[0084] Since the first bus-bar 30 is connected to the DC/AC
inverter 6 by the positive electrode rod 37, high current flows
through the first bus-bar 30 in the vicinity of the positive
electrode rod 37. However, by widening the surface area of the
planar region 33 around the positive electrode rod 37 and
increasing the cross-sectional area, the electrical resistance of
the body of the bus-bar is lowered and heat generation due to high
current flow in the first bus-bar 30 can be controlled. In
addition, by increasing first bus-bar 30 surface area, heat
generated can be easily dissipated to prevent overheating.
[0085] Next, FIG. 13 shows a top view of the second bus-bar 40. The
second bus-bar 40 is the bus-bar disposed at the rear-right side of
FIG. 6, and FIG. 14 shows a side view of the second bus-bar 40 as
viewed from above the center of the upper surface 23 of a
rectangular battery 21. Only parts of the second bus-bar 40 that
are different from the first bus-bar 30 are described below.
[0086] The second bus-bar 40 inclined region 31 of FIG. 13 is
provided with five insertion holes 36 in a straight-line
arrangement to accept insertion of five negative electrode
terminals 24b. The first insertion hole 36a, which is the 5.1 mm
reference hole, is the hole opened closest to the end 35 of the
second bus-bar 40 instead of the hole closest to the opposite end
34 as in the first bus-bar 30. The diameter of the other insertion
holes 36 increases at each hole by 0.1 mm from the reference size
of the first insertion hole 36a towards the end 34 of the second
bus-bar 40. Specifically, in order from the end 35, of the second
bus-bar 40, a first insertion hole 36a with a diameter of 5.1 mm, a
second insertion hole 36b with a diameter of 5.2 mm, a third
insertion hole 36c with a diameter of 5.3 mm, a fourth insertion
hole 36d with a diameter of 5.4 mm, and a fifth insertion hole 36e
with a diameter of 5.5 mm are established. Further, a negative
electrode rod 41 is disposed at the end 34 of the second bus-bar 34
instead of a positive electrode rod 37 at the opposite end 35 of
the first bus-bar 30.
[0087] Based on the second bus-bar 40 structure described above,
effects and features equivalent to those of the first bus-bar can
be expected. Since the contact surface area between negative
electrode terminal surfaces 24B and the second bus-bar 40 is
increased, contact resistance is reduced to increase the amount of
current flow from the rectangular batteries 21 to the second
bus-bar 40. This increases battery 4 output and can yield a high
capacity battery 4. By gradually increasing insertion hole diameter
while reducing hole diameter overall, negative electrode terminal
24b position shift due to expansion of the stacked rectangular
batteries 21 or due to variation in the rectangular batteries 21 or
in the assembly process can be tolerated. Consequently, negative
electrode terminals 24b can be easily inserted in the second
bus-bar 40 and stress is not applied to the second bus-bar 40 as a
result of impact forces or vibration.
[0088] Further, the second bus-bar 40 is connected to the DC/AC
inverter 6 by the negative electrode rod 41, and high current flows
through the second bus-bar 40 in the vicinity of the negative
electrode rod 41. However, by widening the surface area of the
planar region 33 around the negative electrode rod 41 and
increasing the cross-sectional area, the electrical resistance of
the body of the bus-bar is lowered and heat generation due to high
current flow in the second bus-bar 40 can be controlled. In
addition, by increasing second bus-bar 40 surface area, heat
generated can be easily dissipated to prevent overheating.
[0089] Next, FIG. 15 shows a top view of the third bus-bar 42.
Third bus-bars 42 are disposed at the rear-center, the front-left
and front-right sides of FIG. 6, and FIG. 16 shows a side view of
the third bus-bar 42 as viewed from the side-wall 55 of a binding
plate 52, which is described later. Only parts of the third bus-bar
42 that are different from the first bus-bar 30 are described
below.
[0090] The third bus-bar 42 inclined region 31 is provided with ten
insertion holes 36 in a straight-line arrangement to accept
insertion of five positive electrode terminals 24a and five
negative electrode terminals 24b. Accordingly, the length of the
third bus-bar 42 in the rectangular battery 21 stacking direction
in approximately twice that of the first bus-bar 30. The following
describes the third bus-bar 42, which is disposed adjacent to the
first bus-bar 30 in FIG. 6, as an example. The first insertion hole
36a, which is the 5.1 mm reference hole, is one of the two
insertion holes 36 located at the center of the third bus-bar 42.
Of the two center insertion holes 36, the first insertion hole 36a
is the hole closest to the second bus-bar 40, namely the hole
closest to the end 35 of the third bus-bar 42. Insertion hole 36
diameter increases by 0.1 mm at each hole from the first insertion
hole 36a towards both ends 34, 35 of the third bus-bar 42.
[0091] Specifically, in order from the first insertion hole 36a
towards the end 35 of the third bus-bar 42, a second insertion hole
36b with a diameter of 5.2 mm, a third insertion hole 36c with a
diameter of 5.3 mm, a fourth insertion hole 36d with a diameter of
5.4 mm, and a fifth insertion hole 36e with a diameter of 5.5 mm
are established. Further, in order from the first insertion hole
36a towards the opposite end 34 of the third bus-bar 42, a second
insertion hole 36b with a diameter of 5.2 mm, a third insertion
hole 36c with a diameter of 5.3 mm, a fourth insertion hole 36d
with a diameter of 5.4 mm, a fifth insertion hole 36e with a
diameter of 5.5 mm, and a sixth insertion hole 36f with a diameter
of 5.6 mm are established. In addition, where the first bus-bar 30
has a positive electrode rod 37, the third bus-bar 42 has nothing,
and as a result the third bus-bar 42 planar region 33 is truly
planar with no protrusions. If this third bus-bar 42 is rotated
laterally 180.degree., it becomes one of the two third bus-bars 42
disposed in the front part of FIG. 6.
[0092] By making one of the two center insertion holes 36 the
smallest diameter first insertion hole 36a, third bus-bar 42
overall insertion hole 36 diameter (overall insertion hole 36 area)
can be reduced. The insertion hole 36 closest to the end 34 of the
third bus-bar 42 can also be the smallest diameter first insertion
hole 36a. However in that case, the insertion hole 36 closest to
the opposite end 35 of the third bus-bar 42 becomes a large
diameter of 6.0 mm reducing contact surface area and inducing
contact resistance problems. Consequently, that insertion hole
arrangement is undesirable.
[0093] From the description above, since the contact surface area
between positive and negative electrode terminal surfaces 24A, 24B
and the third bus-bar 42 is increased, contact resistance is
reduced to increase the amount of current flow from the rectangular
batteries 21 to the third bus-bar 42. This increases battery 4
output and can yield a high capacity battery 4. By gradually
increasing insertion hole diameter while reducing hole diameter
overall, positive and negative electrode terminal 24a, 24b position
shift due to expansion of the stacked rectangular batteries 21 or
due to variation in the rectangular batteries 21 or in the assembly
process can be tolerated.
[0094] Consequently, positive and negative electrode terminals 24a,
24b can be easily inserted in the third bus-bar 42 and stress is
not applied to the third bus-bar 42 as a result of impact forces or
vibration.
[0095] The third bus-bar 42 is formed as a single-piece that can
both connect rectangular batteries 21 in parallel as a parallel
block 28 and connect parallel blocks 28 in series. Consequently,
the third bus-bar 42 can reduce the number of parts compared to a
system using other parts in addition to the first bus-bar 30 and
second bus-bar 40 to implement series-connection. Further, since
the number of manufacturing and assembly steps can be reduced by
forming the third bus-bar 42 as an integrated single-piece, it is
ideally suited for production in quantity.
[0096] As shown in FIG. 6, positive and negative electrode
terminals 24a, 24b are inserted through the previously described
first through third bus-bars 30, 40, 42 and nuts 50 are tightened
onto the positive and negative electrode terminals 24a, 24b for
solid attachment and connection as shown in FIG. 5. At the ends of
this electrically connected five parallel-four series battery block
20 a pair of endplates 51 is disposed via a pair of intervening
fourth separators 25D. The endplates 51 are made of metal such as
aluminum and are insulated from the rectangular batteries 21 via
the fourth separators 25D, which are made of insulating material
such as resin. Further, since the endplates 51 do not contact the
first through third bus-bars 30, 40, 42 because of the insulating
plates 26 provided on the fourth separators 25D, short circuits can
be prevented.
[0097] The binding plates 52 are fastening components that apply
pressure to the pair of endplates 51 at the ends of the five
parallel-four series battery block 20 and hold the rectangular
batteries 21 in the five parallel-four series battery block 20 with
a strong restraining force. The binding plates 52 are formed to fit
onto both side surfaces and cover both sides of the five
parallel-four series battery block 20. The binding plates 52 and
endplates 51 are fastened together by screws. Further, cut-outs 53
are provided in the binding plate 52 that restrains the first
bus-bar 30 and second bus-bar 40. These cut-outs 53 are provided to
allow the positive electrode rod 37 on the first bus-bar 30 and the
negative electrode rod 41 on the second bus-bar 40 to protrude out
from the upper surface 54 of the binding plate 52. In addition,
cut-out regions (not illustrated) are established through the
side-walls 55 of the binding plates 52 for coolant flow.
[0098] In the first embodiment, voltage detection lines (not
illustrated) to detect the state of the rectangular batteries 21
are connected to positive and negative electrode terminals 24a, 24b
inserted through the first insertion hole 36a in the first through
third bus-bars 30, 40, 42 respectively. The first insertion hole
36a is the smallest hole with a diameter of 5.1 mm, and the contact
surface area between each bus-bar 30, 40, 42 and the electrode
terminal surfaces 24A, 24B are the largest at the first insertion
hole 36a. Consequently, rectangular battery 21 state can be
accurately detected under low resistance conditions at the first
insertion holes 36a. Further, when the contact surface area is
large, the nuts 50 can tightly attach each bus-bar 30, 40, 42. This
allows the state of the rectangular batteries 21 to be stably
detected over a long period allowing the rectangular batteries 21
to be effectively controlled and allowing the battery 4 to be
maintained under optimum conditions.
[0099] Five parallel-four series battery blocks 20 as described
above are arranged in rows and columns as shown in FIG. 4. In FIG.
4, five parallel-four series battery blocks 20 are arranged to
dispose first bus-bars 30 and second bus-bars 40 at the center of
the battery holding case 10, and connectors are used to connect the
four five parallel-four series battery blocks 20 in series. Here,
the two first bus-bars 30 and the two second bus-bars 40 at the
center of the battery holding case 10 can also be replaced by two
third bus-bars 42 to eliminate the connectors. In addition, instead
of the connector that connects the two right-most five
parallel-four series battery blocks 20 in series, the first bus-bar
30 and second bus-bar 40 can also be formed as a single integrated
piece to reduce the number of component parts.
[0100] In the five parallel-four series battery block 20 of FIG. 5,
the positive electrode rod 37 provided on the first bus-bar 30 and
the negative electrode rod 41 provided on the second bus-bar 40 are
positioned at the ends of the bus-bars closest to the center of the
five parallel-four series battery block 20. As a result, the
cut-outs 53 in the upper surface 54 of the binding plate 52 can be
established towards the center of the five parallel-four series
battery block 20. This cut-out 53 arrangement allows binding plate
52 strength to be maintained compared to cut-outs 53 established at
the corners of the upper surface 54 of the binding plate 52 (near
the endplates 51).
[0101] Further, for bus-bars connected to opposite ends of the same
rectangular battery 21 in the five parallel-four series battery
block 20 of FIG. 5, the largest diameter insertion hole 36 is
opposite the smallest diameter insertion hole 36, and the second
largest insertion hole 36 is opposite the second smallest diameter
insertion hole 36. Specifically, the sum of the diameters of the
two opposing insertion holes 36 in bus-bars connected to the same
rectangular battery 21 is either 10.6 mm, 10.7 mm, or 10.8 mm. This
equalizes the sum of opposing insertion hole diameters within the
small range of 10.6 mm-10.8 mm. Consequently, contact resistance
variation among all the rectangular batteries stacked in the five
parallel-four series battery block can suppressed, and the
rectangular batteries 21 can be effectively controlled.
[0102] For rectangular batteries 21 stacked in each parallel block
28, the sum of the diameters of the insertion holes in opposing
bus-bars connected to the same rectangular battery 21 is
essentially equal for all the rectangular batteries 21. This allows
uniform distribution of (small variation in) contact resistance
among the rectangular batteries 21. In a parallel block 28, the
state of all the parallel-connected rectangular batteries 21 is
assumed the same and battery control is performed based on
detection of the state of only one rectangular battery 21.
Therefore, the smaller the variation in rectangular battery 21
contact resistance, the more effectively all the rectangular
batteries 21 can be controlled. Accordingly, the battery 4 can be
maintained in an optimal state.
[0103] Next, the second embodiment of the present invention is
described. Here, component parts that are the same as the first
embodiment are labeled with the same part number and their
description is omitted.
[0104] In the second embodiment, the insertion holes 36 provided in
the first bus-bar 30 and second bus-bar 40 of the first embodiment
are changed. First, the insertion hole 36 located at the center of
the first bus-bar 30 is made the 5.1 mm first insertion hole 36a.
Insertion hole 36 diameter is increased by 0.1 mm at each hole from
the reference first insertion hole 36a towards both ends 34, 35.
Specifically, in order from the first insertion hole 36a towards
one end 34, a second insertion hole 36b with a diameter of 5.2 mm,
and a third insertion hole 36c with a diameter of 5.3 mm are
established. In order from the first insertion hole 36a towards the
other end 35, a second insertion hole 36b with a diameter of 5.2
mm, and a third insertion hole 36c with a diameter of 5.3 mm are
also established. The second bus-bar 40 of the second embodiment is
provided with same insertion hole 36 arrangement as the first
bus-bar 30 of the second embodiment.
[0105] In addition to the features and effects realized by the
first embodiment, the second embodiment can achieve a smaller
bus-bar 30, 40 insertion hole 36 diameter (area) overall by
establishing the smallest diameter first insertion hole 36a at the
center of the bus-bars 30, 40. Compared to the 5.1 mm to 5.5 mm
bus-bar insertion hole diameters in the first embodiment, smaller
5.1 mm to 5.3 mm insertion hole diameters can be achieved in the
second embodiment. As a result, contact surface area between the
bus-bars 30, 40 and the electrode terminal surfaces 24A, 24B can be
further increased allowing contact resistance to be reduced.
Accordingly, the amount of current flowing from the rectangular
batteries 21 to the bus-bars 30, 40 can be increased allowing the
output of the battery 4 to be increased.
[0106] Next, the third embodiment of the present invention is
described. Here also, component parts that are the same as the
first embodiment are labeled with the same part number and their
description is omitted. In the third embodiment, the thickness of
the bus-bars 30, 40, 42, which is uniform in the first embodiment,
is varied according to the amount of current flow. Since the parts
of the bus-bars 30, 40, 42 with high current flow are thickened to
increase the cross-sectional area, electrical resistance in the
body of the bus-bar 30, 40, 42 can be reduced and current-carrying
capability can be increased. By varying the thickness according to
the amount of current flow, bus-bar 30, 40, 42 current flow is made
more uniform and battery 4 output can be increased. Further, since
bus-bar 30, 40, 42 current flow is made more uniform, bus-bar 30,
40, 42 heat generation also becomes more uniform.
[0107] Next, the fourth embodiment of the present invention is
described. Here also, component parts that are the same as the
first embodiment are labeled with the same part number and their
description is omitted. In the fourth embodiment, the surface area
of the bus-bars 30, 40, 42 in the first embodiment is varied
according to the amount of current flow. The surface area of the
parts of the bus-bars 30, 40, 42 where high currents flow is
increased to locally increase the cross-sectional area.
Accordingly, the same type of effects achieved by the third
embodiment can be expected. In addition, by increasing the surface
area, bus-bar 30, 40, 42 heat generation can be easily dissipated
allowing more uniform temperature distribution to be attained
throughout the bus-bars 30, 40, 42.
[0108] Next, the fifth embodiment of the present invention is
described. Here also, component parts that are the same as the
first embodiment are labeled with the same part number and their
description is omitted. In the first embodiment, bus-bars 30, 40,
42 connected to positive and negative electrode terminals 24a, 24b
are all made of the same material. In the fifth embodiment,
bus-bars 30, 40, 42 are used that are made from the same material
as the positive and negative electrode terminals 24a, 24b they
connect.
[0109] For example, aluminum is used to make the first bus-bar 30
that connects to aluminum positive electrode terminals 24a, and
copper is used to make the second bus-bar 40 that connects to
copper negative electrode terminals 24b. Further, aluminum-copper
clad-material can be used to make the third bus-bar 42.
Clad-material is not simply a material that stacks dissimilar
metals together, but rather the dissimilar metals are alloyed
together in a strongly bonded state at the dissimilar metal
junction. Consequently, galvanic corrosion does not occur at the
clad-material junction.
[0110] By connecting each electrode terminal 24a, 24b with a
bus-bar 30, 40, 42 made of the same material, galvanic corrosion
can be prevented. Therefore, compared to the first embodiment,
bus-bars 30, 40, 42 and electrode terminals 24a, 24b can be
electrically connected in a stable, low resistance state over a
long time period.
[0111] Next, the sixth embodiment of the present invention is
described. Here also, component parts that are the same as the
first embodiment are labeled with the same part number and their
description is omitted. In the sixth embodiment, the positive
electrode rod 37 provided on the first bus-bar 30 is established in
the planar region 33 opposite the insertion hole 36 closest to one
end 34 of the first bus-bar 30. The negative electrode rod 41
provided on the second bus-bar 40 is established in the planar
region 33 opposite the insertion hole 36 closest to the other end
35 of the second bus-bar 40. This allows the high current-carrying
positive electrode rod 37 to be established where the electrical
resistance of the body of the first bus-bar 30 is lowest.
Consequently, battery output can be increased. Further, since the
high current-carrying negative electrode rod 41 is established
where the electrical resistance of the body of the second bus-bar
40 is lowest, battery output can be increased.
[0112] In the bus-bars 30, 40 on the five parallel-four series
battery block of FIG. 5, the insertion holes 36 where high current
flows in the sixth embodiment have the smallest diameter, and the
body of the bus-bars 30, 40 has the lowest resistance there.
Further, the size of the insertion holes 36 gradually increases
where the current flow becomes less. Where only a small current
flows in the bus-bars 30, 40, the insertion holes 36 are the
largest and electrical resistance in the body of the bus-bars 30,
40 is largest at those locations. Consequently, current can flow
smoothly (current density can be made more uniform) through the
bus-bars 30, 40, battery 4 output can be increased, and battery 4
performance can be maximized.
[0113] Although an air-cooled forced ventilation cooling system
(with a blower or fan etc.) is adopted as the battery cooling
system in the embodiments of the present invention, the cooling
system is not limited to that method of cooling. All types of
cooling systems such as an air-cooled forced ventilation
negative-pressure (sucking) cooling system, a water-cooling system,
or a cooling system that uses a coolant medium can be used.
Further, the power source apparatus of the present invention is not
limited to the cooling structure in the embodiments, and the power
source apparatus can be provided with any variety of cooling
structures. The presence or absence, the number, and the positions
of intake openings and exhaust openings can be changed at
liberty.
[0114] The battery 4 configuration is not limited to the
configuration in the embodiments. The battery can have a
configuration such as a single parallel block with battery cells
connected in parallel, or it can be a multiple series-parallel
block having parallel-connected groups of multiple battery cells
connected in series. All types of battery configurations can be
used, and design parameters such as the type of battery cells, the
number of stacked battery cells, the stacking method, and the
connection method be also be changed at liberty.
[0115] Although rectangular lithium ion batteries are used as the
batteries in the embodiments, any type of batteries such as nickel
hydride batteries, nickel cadmium batteries, or fuel cells can be
used as the batteries. Further, batteries of any shape such as
circular cylindrical batteries can be used. In addition, the
external case of the batteries can be insulating material allowing
the batteries to be stacked next to each other in an insulated
manner.
[0116] Bus-bar attachment is not limited to the method of
screw-tightening nuts onto the electrode terminals, and methods
such as weld-attachment can also be implemented. There is also no
particular limitation on bus-bar material and bus-bars can be
changed from pure copper to a lower resistance material. Further,
bus-bar shape is not limited to that of the embodiments and all
types of bus-bar shapes can be formulated. The presence or absence
of electrode rods and their locations, the configuration of various
connectors, and other elements are not limited to those of the
embodiments, and the bus-bars can be changed to bus-bars optimally
suited for the power source apparatus architecture.
[0117] The number and size arrangement of the insertion holes
established in the bus-bars can be changed to optimal values and
arrangements. For example, to more equally distribute resistance
among the rectangular batteries, insertion hole size in the second
bus-bar can be changed from the first through fifth insertion hole
sizes to the second through sixth insertion hole sizes. The first
insertion hole in the third bus-bar can be either of the two center
insertion holes, and two adjacent insertion holes in the third
bus-bar could also be the same size. All possible design changes
can be adopted for the insertion holes established in the
bus-bars.
[0118] Components such as the separators, endplates, and fastening
components can be changed according to power source apparatus
architecture and cooling method, and are not limited to those of
the embodiments. All variety of changes can be proposed, such as
changes in number, type, material, and shape. Further, all possible
fastening methods other than screw-fastening, such as welding, can
also be considered.
[0119] Although voltage detection lines are connected to first
insertion holes in the first embodiment, other detection lines such
as temperature detection lines can also be grouped together and
connected. There is also no limitation to detection lines, and
other components such as heaters can also be installed. Further,
the connection points for voltage detection lines are not limited
to the first insertion holes and voltage detection lines can be
connected at the most suitable locations.
[0120] Finally, although bus-bar insertion hole diameter is varied
in the embodiments, an inverse arrangement is also possible where
bus-bar insertion hole diameters are all made the same but
electrode terminal projecting rod sections are instead varied in
size. In addition, instead of providing insulating plates on the
separators, insulating plates can also be formed with the bus-bar
as a single integrated piece. Component parts in the present
embodiments can be changed to conform to all possible design
changes made to the power source apparatus.
POSSIBLE APPLICATIONS IN THE INDUSTRY
[0121] The present invention can be advantageously utilized as a
power source apparatus in vehicles such as a hybrid car (hybrid
vehicle; HV, hybrid electric vehicle; HEV), plug-in hybrid (plug-in
hybrid electric vehicle; PHEV), or electric automobile (electric
vehicle; EV). Further, the present invention can also be favorably
used as a power source apparatus in non-automotive
applications.
[0122] It should be apparent to those with an ordinary skill in the
art that while various preferred embodiments of the invention have
been shown and described, it is contemplated that the invention is
not limited to the particular embodiments disclosed, which are
deemed to be merely illustrative of the inventive concepts and
should not be interpreted as limiting the scope of the invention,
and which are suitable for all modifications and changes falling
within the spirit and scope of the invention as defined in the
appended claims. The present application is based on Application
No. 2009-296705 filed in Japan on Dec. 28, 2009, the content of
which is incorporated herein by reference.
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