Chemistry: electrical current producing apparatus – product – and – Means externally releasing internal gas pressure from closed... – Elastic – resilient or spring biasing valve means
Reexamination Certificate
2000-08-17
2002-10-15
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Means externally releasing internal gas pressure from closed...
Elastic, resilient or spring biasing valve means
C429S161000, C429S178000, C429S174000, C029S623200
Reexamination Certificate
active
06465122
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a storage battery which comprises a battery case used as one polarity terminal and having an opening, a port-sealing body used as other polarity terminal, for sealing the opening, and an electrode body installed into the battery case and having a current collecting body connected to at least one of end portions of positive
egative electrodes and a method of fabricating the same and, more particularly, an improvement of a current collecting structure of a lead portion for connecting the current collecting body connected to at least one of the positive
egative electrodes and the port-sealing body of a solution battery such as alkaline cell and lead cell and a welding method therefor.
2. Description of the Related Art
In general, the alkaline storage battery such as the nickel-hydrogen storage battery, the nickel-cadmium storage battery, or the like are constructed by interposing the separator between the positive electrode and the negative electrode, then winding them spirally, then connecting the current collecting body to the end portion of the positive electrode or the negative electrode to form the electrode body, then installing the electrode body into the metal battery case, then welding the lead portion extended from the current collecting body to the port- sealing body, and then fitting the port-sealing body to the opening portion of the battery case via the insulation gasket to seal tightly the battery case.
In case such alkaline storage battery is employed in the application such as the electric-powered tool, the electric. vehicle, etc. in which charging/discharging operations are performed at a high rate, the electric resistance of the lead portion which connects the current collecting body and the port-sealing body affects largely the battery characteristic. Thus, if the electric resistance of the lead portion is large,. there is such a problem that, when the discharge is performed by the large current, the voltage drop due to the electric resistance of the lead portion is caused to lower the battery voltage. Therefore, in Japanese Patent No. 2762599, it has been proposed to reduce the electric resistance of the lead portion by using plural sheets of current collecting parts to construct the lead portion or increasing the thickness of the current collecting parts.
Meanwhile, in case a plurality of current collecting parts constituting the lead portion are employed, such problems are caused that the welding to the port-sealing becomes difficult since not only the number of parts is increased but also the lead portion lacks the flexibility and that productivity is deteriorated since it becomes difficult to fold the lead portion when the port-sealing body is caulked to the opening portion of the battery case to seal. Also, in case the thickness of the current collecting parts constituting the lead portion is increased, such problems are caused that weldability to the port-sealing body is deteriorated since the reactive current is increased in the welding current for the resistance welding and that the productivity is deteriorated since it becomes difficult to fold the lead portion when the port-sealing body is caulked to the opening portion of the battery case to seal.
In contrast, in case the lead portion is welded to the port-sealing body, first the lead portion is resistance-welded to the port-sealing body while pushing the welding electrode against the side surface of the lead portion after the port-sealing body is positioned in the neighborhood of the lead portion that stands perpendicularly from the current collecting body. After this, the port-sealing body is fitted into the opening portion of the battery case by folding the lead portion and then the edge portion of the opening portion is caulked to seal tightly. Normally, if the lead portion that is thick and short is employed, its specific resistance can be reduced and thus the internal resistance of the battery can be lowered.
However, as described above, in order to fit the port-sealing body into the opening portion of the battery case after the lead portion is welded to the port-sealing body, the port-sealing body must be fitted into the opening portion of the battery case by using the longer lead portion so as to fold the lead portion at the time of sealing. Therefore, a length that exceeds at least a radius of the electrode body is needed as the length of the lead portion, and also the thin and long lead portion must be employed such that the lead portion can be folded. Thus, there is caused the problem that, since the specific resistance of the lead portion is increased, the internal resistance of the battery is increased.
Therefore, the connecting method of reducing the internal resistance of the battery by reducing the current collecting route has been proposed in unexamined Japanese Patent Publication (JP-A) 10-261397, for example. According to this method, the electrode body is installed into the battery case, then the opening portion of the battery case is sealed tightly by the port-sealing body in the situation that the lead portion welded to the current collecting body is brought into contact with the lower surface of the port-sealing body, and then the contact portion between the lead portion and the port-sealing body are welded by flowing current between the battery case and the port-sealing body.
Accordingly, it is possible to install easily the port-sealing body into the opening portion of the battery case if the lead portion is short, and it is possible to reduce the internal resistance of the battery by reducing the current collecting distance. Also, since there is no need to fold the lead portion in sealing the opening, it is possible to use the thick lead portion and also it is possible to reduce the internal resistance of the battery.
However, in the connecting method proposed in JP-A 10-261397, in case the height of the electrode body installed in the battery case is varied, the situation may occur wherein the contact portion between the port-sealing body and the lead portion cannot be surely formed. Thus, the problem arises that the welding portion cannot be firmly formed. Also, the strength and the quality of the welding spot after welding is deteriorated only by bringing the lead portion into contact with the port-sealing body, and in some cases yield of the product is degraded.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made to overcome the above problems, and it is a first object of the present invention to obtain a storage battery which is excellent in high-rate discharge performance by using lead parts which can weld a port-sealing body and a current collecting body without fail even if its thickness is large and its length is small. Also, it is a second object of the present invention to provide a welding method capable of welding the lead portion and the port-sealing body or the lead portion and the current collecting body by using such lead parts to connect them without fail.
In order to achieve the above first object, the battery of the present invention the lead portion for connecting the port-sealing body and the current collecting body is constructed by the cylindrical body having the hollow portion, then this cylindrical body having the hollow portion is provided between the port-sealing body and the current collecting body, and then the port-sealing body and the current collecting body are welded to the lead portion formed of the cylindrical body.
If the port-sealing body and the current collecting body are welded to the lead portion having the hollow portion and formed of the cylindrical body, the current route in supplying the current is divided into two routes from the current collecting body to the port-sealing body (otherwise, from the port-sealing body to the current collecting body) along the peripheral side wall of the cylindrical body to flow the current. Hence, the current collecting distance of the lead portion becomes the semicircle of the cylindric
Ikemachi Takaaki
Kitaoka Kazuhiro
Tamezane Shigeto
Kalafut Stephen
Nixon & Vanderhye P.C.
Sanyo Electric Co,. Ltd.
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