Chemistry: electrical current producing apparatus – product – and – Cell support for removable cell – For plural cells
Reexamination Certificate
2001-06-27
2004-11-16
Cantelmo, Gregg (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Cell support for removable cell
For plural cells
C429S120000, C429S148000, C429S149000, C429S152000
Reexamination Certificate
active
06818343
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a rechargeable battery configured in the form of a battery pack in which a plurality of cells are connected so as to obtain the required electrical capacity, and more particularly to a rechargeable battery in which the heat radiation of the battery pack is enhanced and there is less temperature differential between cells, so that charging efficiency is equalized and there is no variance in the battery capacity of the various cells.
BACKGROUND ART
A conventional rechargeable battery constructed such that the required electrical capacity is obtained by connecting and integrally linking a plurality of cells into a battery pack is structured as shown in
FIG. 16
, for example. This rechargeable battery is an example of a battery pack made up of sealed alkaline rechargeable batteries, and the cells
1
a
to
1
j
that make up this battery pack are constructed as shown in FIG.
15
.
In
FIG. 15
, the cell
1
is constructed such that a group of electrode plates
7
, comprising positive and negative electrode plates layered with separators between them, is housed in a battery housing
2
along with electrolyte, the opening in the battery housing
2
is closed off with a cover
6
provided with a safety vent
5
, and a positive electrode terminal
3
, which is connected to leads taken from the positive electrode plates of the group of electrode plates
7
, and a negative electrode terminal
4
, which is connected to leads
9
taken from the negative electrode plates, are attached to the cover
6
.
When the battery pack is put together, as shown in
FIG. 16
, the plurality of cells
1
a
to
1
j
are abutted against each other between the long (wide) sides of the battery housings
2
, and the end plates
32
, which are abutted against the outsides of the battery housings located at the ends, are bound together with binding bands
33
to integrally link the cells
1
a
to
1
j
. The positive electrode terminals
3
and negative electrode terminals
4
between linked adjacent cells
1
are connected by connector plates
31
, and the cells
1
are connected in series. When the battery housings are linked, ribs
8
formed vertically on the long sides of the battery housings
2
are aligned with the ribs
8
on the adjacent battery housings
2
, forming coolant passages that open above and below the battery housings
2
between the paired ribs
8
.
A rechargeable battery generates joule heat and reaction heat through the chemical reaction that accompanies charging and discharging. The greater is the electrical capacity, the more heat is generated, and if the battery is sealed, the radiation of heat to outside the battery is slowed and even more heat builds up inside the battery, so when a battery pack with a large electrical capacity is made up of sealed rechargeable batteries, it is essential to provide some means for the efficient radiation of the heat that is generated. With the conventional rechargeable battery structure shown in
FIG. 16
, the coolant passages are formed by the ribs
8
between adjacent cells
1
as mentioned above, so heat generated by the cells
1
can be effectively radiated by forcing a coolant such as air through these coolant passages. A heat radiation structure such as this is disclosed in Japanese Laid-Open Patent Application No. 3-291867.
Nevertheless, when a battery pack is produced by arranging cells as in this conventional structure, a problem is that the greater is the number of cells
1
arranged, the greater is the temperature differential between the cells
1
located toward the middle and the cells
1
located on the outer ends. With the conventional structure shown in
FIG. 16
, the cells
1
a
and
1
j
located on the outer ends are less subjected to the effects of the heat generated by the other cells
1
, and the end plates
32
also carry away some of the heat, so these cells are under good thermal radiation conditions. The closer a cell
1
is to the middle, the more it is affected by the heat generated by the cells
1
to either side, so the temperature rises more and heat radiation is not as good. Consequently, with a conventional structure, the closer a cell
1
is to the middle, the worse its heat radiation conditions are, the result being a temperature differential in which the temperature of the cells
1
a
to
1
j
is lower toward outside and higher toward the middle.
The charging efficiency of a rechargeable battery is affected by the temperature thereof, so if there is a temperature differential between the cells that make up the battery pack, as with a conventional structure, there will be a difference in the electrical capacity of the various cells. With a battery pack in which cells whose capacity thus varies are connected in series, those cells with lower capacity are in a state of overdischarge at the end of discharge. Repeated charging and discharging in this state in which there is a difference in the capacity of the cells shortens the cycling life of a battery pack and leads to diminished dischargeable capacity.
It is an object of the present invention to provide a rechargeable battery with enhanced performance as a battery pack, with no temperature differential between the cells that make up the battery pack.
DISCLOSURE OF THE INVENTION
The rechargeable battery according to a first aspect of the present invention for achieving the above object is characterized in that a battery housing containing elements for electromotive force of a cell is formed in a rectangular shape having short sides with a narrow width and long sides with a wide width, and a plurality of cells are linked together adjacent to one another between the short sides of this battery housing to form a battery pack with a required electrical capacity.
With the structure of this rechargeable battery, the plurality of cells that make up the battery pack are arranged in a single row with the short sides of the battery housings next to each other, so the long sides of the cells all face outward and the temperature environment thereof is equalized, resulting in an extremely small temperature differential between the cells. Therefore, there is also less difference in charging efficiency, which varies with the battery temperature, and there is no variance in the cell capacity, so none of the cells is overdischarged during discharging, and the cycling life of the rechargeable battery can be kept long.
The rechargeable battery according to a second aspect of the present invention for achieving the above object is characterized in that a battery housing containing elements for electromotive force of a cell is formed in a rectangular shape having short sides with a narrow width and long sides with a wide width, a plurality of cells are linked together adjacent to one another between the short sides of their battery housings to form battery modules, these battery modules are arranged in parallel in a plurality of rows adjacent to one another between the long sides of the battery housings, and the plurality of rows of battery modules are linked together to form a battery pack with a required electrical capacity.
With the structure of this rechargeable battery, the plurality of cells that make up the battery pack are arranged in a single row with the short sides of the battery housings next to each other, thus forming a battery module, and these battery modules are arranged in parallel in a plurality of rows, so the long sides of the cells face outward and the temperature environment is equalized, resulting in an extremely small temperature differential between the cells. Therefore, there is also less difference in charging efficiency, which varies with the battery temperature, and there is no variance in the cell capacity, so none of the cells is overdischarged during discharging, and the cycling life of the rechargeable battery can be kept long. It is also possible to increase the number of battery modules linked or shorten the linkage length by further disposing in parallel battery modules linked on the short sides.
In the ab
Asakawa Kieko
Fukuda Shinsuke
Katsuta Toshihiro
Kimoto Shinya
Kimura Kenji
Cantelmo Gregg
Jordan and Hamburg LLP
Matsushita Electric - Industrial Co., Ltd.
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