Chemistry: electrical current producing apparatus – product – and – Plural concentric or single coiled electrode
Reexamination Certificate
2001-06-28
2004-03-09
Bell, Bruce F. (Department: 1746)
Chemistry: electrical current producing apparatus, product, and
Plural concentric or single coiled electrode
C429S133000, C429S164000
Reexamination Certificate
active
06703158
ABSTRACT:
TECHNICAL FIELD
This invention relates to a cylindrical storage battery provided with a spirally coiled electrode plate assembly, and more particularly to an alkaline storage battery for use as a drive power source of a vehicle, in which a lead terminal, electrically connecting a current collector, welded to an upper portion of the electrode plate assembly, to a sealing plate, is improved so as to enable charge and discharge with a large electric current and also to achieve excellent vibration-resistant properties.
BACKGROUND ART
Cylindrical storage batteries, represented by a nickel-cadmium storage battery and a nickel-metal hydride storage battery, have been widely used as a power source of a mobile phone, a laptop personal computer and so on because of their high reliability and easy maintenance. In recent years, there has been an increasing demand for the type of cylindrical storage battery suited for large-current discharge so as to be used as a power source of an electrically-operated tool, a power-assisted bicycle, an electric car and so on.
A cylindrical storage battery is formed by spirally winding a strip-shaped positive electrode plate and a strip-shaped negative electrode plate, with a separator interposed therebetween, to provide an electrode plate assembly, then by inserting this assembly, together with an electrolyte, into a casing made of metal, and then by closing an opening of this casing in a sealed manner.
In the type of alkaline storage battery used for discharging large current, a positive electrode plate and a negative electrode plate are wound in such a manner that an upper end portion of one of the positive and negative electrode plates projects upwardly from an upper end of an electrode plate assembly while a lower end portion of the other electrode plate projects downwardly from a lower end of the electrode plate assembly, and current collectors of a rectangular or a circular shape are welded respectively to the upwardly-projecting distal end and downwardly-projecting distal end of the two electrode plates at a plurality of spots, thereby enhancing the ability to collect electric current from the electrode plates. However, a resistance drop develops particularly at a lead terminal, connecting the electric collector to a sealing plate, thus inviting a problem that the operating voltage of the battery decreases, and besides there has been a possibility that the sealing plate and the lead terminal portion are disengaged from each other upon application of severe vibration and impact.
For example,
FIG. 9
shows a horseshoe-shaped lead terminal
17
(disclosed in Japanese Utility Model Laid-Open Publication No. 58-74768) connected to a sealing plate
11
as shown in FIG.
10
. The positioning of the lead terminal
17
is effected by loosely fitting its opening portion
17
a
on a projected portion
11
a
of the sealing plate
11
in contacted relation thereto, and a horseshoe portion
17
b
of the lead terminal
17
is connected to the sealing plate
11
by spot welding as shown in
FIG. 10
which is a schematic, cross-sectional view. In this case, the lead terminal
17
is formed integrally with an electric collector
18
.
In the structure shown in
FIG. 9
, however, when positioning the horseshoe portion
17
b
of the lead terminal
17
relative to the projected portion
11
a
of the sealing plate
11
, this positioning can not be effected accurately unless the proximal end portion of the opening portion is held in contact with the projected portion
11
a
. Therefore, if even a slight displacement occurs, variations in the spot welded positions and an incompletely-welded condition are encountered. And besides, the lead terminal
17
has a horseshoe-shape, and therefore is not held against a side surface of the projected portion
11
a
, and therefore a load acts directly on the spot welded portions upon being subjected to vibrations, so that the spot welded portions are broken. Furthermore, the lead terminal
17
and the current collector
18
are formed into an integral construction, and the lead terminal
17
is formed on the outer peripheral edge of the current collector
18
, and therefore particularly a current collecting portion
18
a
(of the current collector
18
connected to the electrode plate) remotest from the lead terminal
17
has a longer path of flow of electric current as compared with other current collecting portions
18
b
and
18
c
, and this causes the increase of an internal resistance of the battery.
DISCLOSURE OF THE INVENTION
In order to solve the above problems, the present invention provides a cylindrical storage battery which comprises current collectors, welded respectively to distal ends of strip-shaped positive and negative electrode plates projecting upwardly and downwardly respectively from a spirally coiled electrode plate assembly including the electrode plates and a separator, and a lead terminal connecting one of the current collectors to a sealing plate. In this storage battery, a hole is formed through one end portion of the lead terminal to be connected to the sealing plate, and this hole is fitted on a projected portion of the sealing plate. In one method, that portion of the lead terminal, surrounding this hole, is fixedly secured to the reverse surface of the sealing plate by laser welding. In another method, a plurality of projections or a ring-shaped projection are formed on that portion of the lead terminal surrounding the hole, and the projection or projections is/are secured to the reverse surface of the sealing plate. With this construction, the positioning of the lead terminal and the sealing plate relative to each other can be carried out easily, and therefore the welding connection can be effected in a stable manner, and besides this structure can withstand severe vibrations.
Further, a hole or a notch is formed through the other end portion of the lead terminal to be welded to the current collector, and that portion of the lead terminal, surrounding this hole, is held against a central portion of a flat plate portion of the current collector. In this case, the central portion is spaced from the center by a distance not larger than a half of the distance between the center and the outer peripheral edge. In one method, the portion of the lead terminal, surrounding the hole or the notch, is secured to the flat plate portion of the current collector by laser welding. In another method, a plurality of projections or a ring-shaped projection are formed on this portion surrounding the hole, and the projection or projections is/are secured to the current collector. With such construction, the paths of flow of electric current from current-collecting portions of the current collector, welded to the electrode plate, to the lead terminal, can be made shortest.
According to one aspect of the invention, there is provided a cylindrical storage battery comprising: an electrode plate assembly including a pair of strip-shaped positive and negative electrode plates and a separator which are spirally wound in such a manner that a distal end portion of one of the electrode plates projects upwardly from the electrode plate assembly while a distal end portion of the other electrode plate projects downwardly from the electrode plate assembly; a pair of upper and lower current collectors welded respectively to the distal end portions of the electrode plates, each of the current collectors being in the form of a flat plate of a substantially rectangular or a substantially circular shape; a metal casing containing the electrode plate assembly, the current collectors and an alkaline electrolyte therein; a sealing plate closing an upper end of the casing in a sealed manner; and a lead terminal electrically connecting the upper current collector to the sealing plate; wherein a projected portion is formed on a lower surface of the sealing plate, one end portion of the lead terminal has a hole fitted on the projected portion of the sealing plate, a projection is formed on that portion of the lead terminal surrounding the hole, a
Bell Bruce F.
Scaltrito Donald V.
LandOfFree
Cylindrical storage battery does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cylindrical storage battery, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cylindrical storage battery will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3188818