Chemistry: electrical current producing apparatus – product – and – Sealed cell having gas prevention or elimation means
Reexamination Certificate
2000-04-14
2001-12-04
Maples, John S. (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Sealed cell having gas prevention or elimation means
C429S071000, C429S089000
Reexamination Certificate
active
06326100
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cylindrical secondary battery, and more particularly, to a cylindrical secondary battery having a one-way valve in a cap assembly to exhaust gas generated during charging the battery.
2. Description of the Related Art
Batteries are electrical products for supplying a DC voltage. There are various types of batteries used for various electrical or electronic products and devices and rechargeable batteries used for vehicles and as emergency power for mechanical apparatuses. Batteries which are not rechargeable are generally referred to as primary batteries while ones capable of discharge and recharge by being provided with electricity from other electric powers are referred to as secondary batteries.
FIG. 1
is a sectional view showing the structure of a typical cylindrical secondary battery, Referring to the drawing a conventional secondary battery
10
includes a case
14
of a cylindrical can shape and an anode plate
16
and a cathode plate
17
installed in the case
14
. The anode plate
16
and the cathode plate
17
are formed in strips having predetermined widths and lengths. A separator
18
is interposed between the anode plate
16
and the cathode plate
17
to prevent the anode plate
16
and the cathode plate
17
from contacting each other. In such a state, the anode plate
16
and the cathode plate
17
are rolled forming a jelly-roll.
Thus, the anode plate
16
and the cathode plate
17
, which are rolled with interposition of the separator
18
, alternate. Upper and lower ring members
15
a
and
15
b
supporting an insulation member
18
are installed at the upper end and the lower end of a jelly-roll of the anode plate
16
and the cathode plate
17
, respectively.
A gasket
13
is arranged above the upper ring member
15
a
and a cap cover
12
and a cap
11
supported by the gasket
13
are provided. A fragile portion
19
is formed at the central position of the cap cover
13
a
. The fragile portion
19
is integrally formed with the cap cover
12
and, when the pressure inside the case
14
increases, the fragile portion
19
is broken to exhaust gas.
FIG. 2
is an exploded perspective view showing a cap assembly of the battery shown in FIG.
1
. Referring to the drawing, the fragile portion
19
is located at the central portion of the cap cover
12
as described above and a bending portion
12
a
, which is bent during assembly, is formed at the edge of the cap cover
11
. The fragile portion
19
is formed by forming a notch or a thin portion at the central portion of the cap cover
12
to partially decrease breaking strength. Thus, when the pressure in the case
14
increases, the fragile portion
19
is broken so that gas can be exhausted.
The process of manufacturing a battery having the above structure includes steps of inserting the anode plate
16
and the cathode plate
17
in the case
14
, injecting electrolyte, and arranging a cap assembly including the cap
11
above the case
14
. In performing a sealing process with respect to the cap assembly, a cathode tap at the cathode plate
17
is welded at a predetermined position of the cap assembly so that a stable electrical connection to the cathode plate
17
is maintained. Contrarily, as the anode plate
16
directly contacts the inner surface of the case
14
, an electrical connection is achieved.
A charge process is performed before completed batteries are shipped as products. That is, secondary batteries are charged to a degree before they are shipped as products. Typically, it is known that gas is generated most in a secondary battery when the initial charge is performed. As gases generated during the initial charge, there are hydrogen carbon monoxide, carbon dioxide and hydrocarbons. As other gases are generated in addition to the above, there is a possibility of explosion. However, there has not been a method for effectively exhausting the generated gas. That is, although gas can be exhausted to the outside by forming the fragile portion
19
at the cap cover
12
and breaking the fragile portion
19
when the gas pressure increases over a predetermined value of pressure, if the fragile portion
19
is broken, the cap assembly cannot be used again.
SUMMARY OF THE INVENTION
To solve the above problem, it is an objective of the present invention to provide a cylindrical secondary battery having a valve for arbitrarily exhausting gas generated inside a case of the second battery.
Accordingly, to achieve the above objective, there is provided a cylindrical secondary battery comprising a case, a cathode plate and an anode plate alternately installed in the case and a separator interposed therebetween, a cap disposed above the case and a cap cover coupled to the cap and having a vent hole formed therein, and a one-way valve installed at the vent hole. The one-way valve comprises a hollow body portion which can be inserted in the vent hole of the cap cover, a plurality of gas passing grooves formed at the outer circumferential surface of the hollow body portion, an upper flange formed at the outer circumferential surface of the hollow body portion to be disposed above the cap cover, a lower flange formed at the outer circumferential surface of the hollow body portion to be disposed under the cap cover, a spring elastically supported between the upper flange and the cap cover, and a fragile portion closing the upper portion of the hollow body portion.
It is preferred in the present invention that, when an external force is not applied to the one-way valve, an upper surface of the lower flange closely contacts the bottom surface of the cap cover, forming a seal, and when an external force is applied to the one-way valve, the gas passing grooves arrive at the position corresponding to the vent hole so that gas in the case can be exhausted.
Also, it is preferred in the present invention that the fragile portion is broken when the pressure in the case is over a predetermined value so that gas in the case can be exhausted.
REFERENCES:
patent: 5407760 (1995-04-01), Kasner et al.
patent: 6051332 (2000-04-01), Verhoog et al.
patent: 6255013 (2001-07-01), Marukawa et al.
Choi Yun-seok
Han Se-jong
Leydig , Voit & Mayer, Ltd.
Maples John S.
Samsung SDI & Co., Ltd.
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