JP2005216768A - Sealed storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed storage battery suitable for quick charging, housing a pressure switch mechanism inside, easy to set a valve opening pressure, with low scatter of valve opening pressure, free from such a disorder that the pressure valve opens before the pressure switch is operated when the storage battery is quickly charged, or a seal is broken caused by the disorder of the valve. <P>SOLUTION: The sealed storage battery, housing the pressure switch mechanism connecting and disconnecting a charge current to be supplied to the battery in compliance with the inner pressure thereof, comprises: a through-hole 10 formed on a connection terminal 6 as a component member of the pressure switch, which is sealed by a sealing plug 9 at normal time; and a valve opening means opening the through-hole by breaking or removing the sealing plug when the inner pressure of the battery is abnormally increased. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The central part of the grommet moves up and down due to changes in the internal pressure of the storage battery during charging, and the cylindrical connection terminal attached to the central part of the grommet moves up and down in conjunction with this to cut off and connect the charging current switch. The present invention relates to a sealed storage battery having a current interrupting connection mechanism.

  As a sealed storage battery mainly used as a power source for portable equipment, there are a nickel metal hydride storage battery, a nickel cadmium battery, a small sealed lead battery, and a lithium ion battery. In particular, nickel-metal hydride storage batteries are excellent in charge / discharge cycle performance and are frequently used as storage batteries suitable for cycle service. If these sealed batteries are overcharged or overdischarged, or charged or discharged with a large current, the electrolyte is decomposed and gas is generated, the internal pressure of the battery rises, and eventually the battery seal is broken. In extreme cases, the storage battery may burst. In recent years, there has been a demand for shortening the charging time for a storage battery for cycle service, and a technology that enables unprecedented quick charging to complete charging in 15 to 30 minutes in order to meet the request. It is being developed.

For example, when an attempt is made to charge a sealed nickel-metal hydride storage battery by rapid charging as described above, gas is generated due to decomposition of the electrolyte in the battery as the battery temperature rises, and the internal pressure of the storage battery increases. To prevent battery temperature and internal pressure from rising abnormally during charging,
Focusing on the rise in internal battery pressure during charging, a sealed storage battery with a mechanism (hereinafter referred to as a pressure switch) capable of interrupting and connecting the charging current by changing the internal pressure of the battery during charging is proposed. Has been. (For example, see Patent Document 1)

US Patent Specification US2002 / 0119364 (FIG. 2A, FIG. 2B) The sealed storage battery proposed in this patent document has a pressure switch structure as shown in FIG. In FIG. 4, reference numeral 4 denotes an electric can that accommodates the electrode group 12, and the connection terminal 6 is inserted through a through hole provided in a central portion of the grommet 5, which is a synthetic resin molded product. It is sealed in the same manner as when a gasket is applied by clamping the part to the open end of the battery case (crimp seal method). The connection terminal 6 and the positive electrode constituting the pole group 12 are connected by a positive electrode tab terminal 13, and the cap 1 and the second terminal 2 of the pressure switch are fitted into the grommet 5. A pressure spring 3 is disposed in a space surrounded by the second terminal 2 of the pressure switch and the cap 1, and the pressure switch is normally joined to the connection terminal 6 by the pressing force of the pressure spring 3. The first terminal 7 is pressed against the second terminal 2 of the pressure switch, and the pressure switch is on.

  The central part of the grommet 5 is formed thin so that it can be bent upward and deformed according to the internal pressure of the storage battery. When the internal pressure of the storage battery increases during charging, the central portion of the grommet 5 bends and deforms upward, and the first terminal 7 of the pressure switch moves upward in conjunction with the deformation, and the second terminal 2 of the pressure switch. The pressure switch turns off to leave. When the internal pressure of the storage battery decreases, the first terminal 7 of the pressure switch moves downward by the pressing force of the pressure spring 3 and returns to the original position, and the pressure switch returns to the on state.

  As described above, in the sealed storage battery having the configuration shown in FIG. 4, the gasket is bent and deformed by the change in the internal pressure of the storage battery during charging, and the first terminal 7 of the pressure switch attached to the grommet is moved up and down. A structure for controlling on / off of the pressure switch is provided.

According to the above proposal, when the battery internal pressure reaches a certain pressure during charging, the charging current is cut off, and when the battery internal pressure falls below the certain pressure, the battery is connected again and charged, and the on / off (pulse) linked to the battery internal pressure change. ) Charging is performed.
This on / off charging mechanism moves the grommet up and down due to the internal pressure change of the storage battery during charging, and the cylindrical current extraction terminal attached to the grommet moves up and down in conjunction with the charging current switch. Is configured to be cut off and connected.

  Such a sealed storage battery having a mechanism capable of interrupting and energizing the charging current due to a change in the internal pressure of the battery during charging causes the battery temperature to rise due to the charging current control by the internal pressure change. It has features that can be suppressed. In addition to overcharging, the internal pressure of the storage battery rises abnormally when the battery is exposed to high temperatures other than when it is overcharged, overdischarged or discharged with a large current, eventually destroying the crimp seal. There is a risk of reaching. Therefore, in consideration of when the switch mechanism does not operate normally or when the battery is exposed to high temperature, the gas accumulated inside the storage battery is released to the outside separately from the pressure switch. It is desirable to provide a mechanism (hereinafter referred to as a valve mechanism or a valve).

  In a sealed storage battery incorporating the pressure switch, as a simple valve mechanism, for example, a thin portion 8 is provided in the grommet 5 and the thin portion provided in the gasket is broken when the pressure inside the storage battery rises abnormally. There is a valve mechanism that discharges the gas accumulated inside.

  However, in the case of a valve mechanism in which the thin portion 8 provided in the grommet 5 is broken and the gas accumulated therein is discharged as a result of examination, for example, if the grommet 5 which is a molded product of polypropylene resin is to be broken, it is extremely large It is necessary to reduce the thickness of the thin portion to about a few millimeters. Moreover, since the said breaking strength is influenced not only by the dimensional accuracy of a thin part but the flow of the resin at the time of shaping | molding, variation tends to become large. Furthermore, stress is applied to the grommet in the process of inserting a connection terminal into a through-hole provided in the center of the grommet or crimp-sealing when assembling the battery, and the stress changes the breaking strength of the thin portion 8 having low mechanical strength. Therefore, there is a tendency that the variation in the operating pressure of the valve opening is further increased. In this way, in order to break the grommet by providing a thin part, the operating pressure of the valve opening is unstable and varies widely, and in extreme cases during normal use (the internal pressure of the storage battery increases abnormally). It has been found that there is a drawback that the valve is opened even in a state where it is not.

  The present invention has been made in view of the drawbacks of the prior art, and in a sealed storage battery having a pressure switch mechanism that turns on and off a charging current in response to the internal pressure of the storage battery during charging. It is an object of the present invention to provide a sealed battery with a highly reliable valve opening operation with a stable valve opening operation.

In this invention, the said subject can be solved by setting it as the following structures.
A sealed storage battery according to the present invention is a sealed storage battery that incorporates a current on / off switch mechanism that cuts off or energizes a charging current in response to a change in internal pressure of the storage battery during charging,
When the internal pressure of the storage battery rises abnormally, the sealed storage battery is characterized by comprising valve-opening means for forming a through-hole in a connection terminal that goes up and down due to a change in the internal pressure of the storage battery. (Claim 1)

  In the sealed storage battery according to the present invention, the inner or outer end of the through-hole communicating between the inside and the outside of the battery provided in the connection terminal is sealed with a sealing plug, and when the internal pressure of the storage battery rises abnormally, 2. The sealed storage battery according to claim 1, wherein the sealing plug is broken or eliminated. (Claim 2)

  In the sealed storage battery according to the present invention, the inner end of a through hole that communicates the inside and outside of the battery provided in the connection terminal is sealed with a sealing plug, and when the internal pressure of the storage battery rises abnormally, the penetration 3. The sealed storage battery according to claim 2, wherein a rod-shaped member disposed in the hole presses the sealing plug to break or eliminate the sealing plug. (Claim 3)

The sealed storage battery according to the present invention has a resin sealing plug fitted to the inner end of the through hole that communicates the inside and outside of the battery provided in the connection terminal, and when the internal pressure of the storage battery rises abnormally, 4. The sealed storage battery according to claim 3, wherein the resin-made sealing plug is pushed downward by a rod-shaped member disposed in the through-hole pressing the sealing plug. 5. (Claim 4)
Here, the abnormal increase in the internal pressure of the storage battery here means a state in which the internal pressure increases beyond the operating pressure of the pressure switch.

In invention of Claims 1-4, compared with what forms a thin part in the conventional grommet, and uses this thin part as a valve,
Since the variation in the valve opening pressure of each battery can be reduced, it is not necessary to set the valve opening pressure low. For this reason, in the battery at the time of normal use, the problem which the malfunction etc. which the thin part of a grommet fractures | ruptures and becomes a lifetime can be solved. Moreover, according to the invention of Claim 4, it can be set as the sealed storage battery with easy assembly of a valve opening mechanism.

Hereinafter, the present invention will be described with reference to embodiments, but the present invention is not limited thereto.
(First embodiment)
A first embodiment of the valve opening structure of the nickel metal hydride battery of the present invention will be described with reference to FIG.
In FIG. 1, reference numeral 4 denotes an electric can that accommodates a pole group 12, and is sealed by a grommet 5 having a columnar connection terminal 6 mounted at the center.
The grommet 5 is a molded product made of, for example, polypropylene, and a horizontal wall portion 5 'is thinly molded in order to impart flexibility to the central portion. The connection terminal 6 and the positive electrode constituting the pole group 12 are connected by a positive electrode tab terminal 13, and the grommet 5 is fitted with a metal cap 1 and a second terminal 2 of a pressure switch. The cap 1 is provided with a small hole 14 for communicating the space inside the cap and the external space.
Also, a metal pressure spring 3 is arranged in a space surrounded by the second terminal 2 of the pressure switch and the cap 1, and the first terminal 7 of the pressure switch joined to the connection terminal 6 is normally the pressure switch. The pressure switch is turned on by being pressed against the surface of the second terminal 2.

  When the internal pressure of the storage battery rises, the grommet 5 is bent upward by being pushed by the internal pressure, and the first terminal 7 of the pressure switch moves upward in conjunction with the deformation, and the second terminal of the pressure switch. 2 and the pressure switch is turned off. When the internal pressure of the storage battery decreases, the grommet 5 is deformed downward by the pressing force of the spring 3, and the first terminal 7 of the pressure switch moves downward to the second terminal 2 of the pressure switch. The pressure switch returns to the on state upon contact. An insulating film 15 is disposed between the pressure spring 3 and the first terminal 7 of the pressure switch, and the pressure spring 3 and the first terminal 7 of the pressure switch are insulated.

  In the present invention, as shown in FIG. 1, the connection terminal 6 is provided with a through hole 10 for communicating the battery internal space and the external space. In the present embodiment, the through hole 10 is sealed by fitting a sealing plug 9, which is a molded product of a soft resin (for example, thermoplastic resin) or rubber such as polypropylene, to the inner end portion of the through hole 10. Further, a rod-shaped member 11 is disposed inside the through hole 10. At all times (the state where the central portion 5 of the grommet is not bent upward and deformed), the length of the rod-shaped member 11 is shorter than the distance between the inner surface of the cap 1 and the end surface of the sealing plug 9, and the sealing plug 9 On the other hand, no downward pressing force is applied. However. When the pressure inside the battery rises abnormally, the central portion of the grommet 5 bends upward, the distance between the inner surface of the cap 1 and the sealing plug 9 is shortened, and one end surface of the rod-shaped member 11 contacts the inner surface of the cap 1. When the central portion of the grommet 5 is further bent upward and deformed, the rod-like member 11 presses the sealing plug 9 downward, and finally the sealing plug 9 is pushed out from the through hole 10 and accumulated in the internal space of the battery. The gas is discharged to the outside through the through hole 10.

  The main factors that determine the valve opening operating pressure in the present embodiment are the degree of the bending deformation of the central portion of the grommet 5, the length of the rod-shaped member 11, the distance between the inner surface of the cap 1 and the sealing plug 9, and the penetration The sealing plug 9 inserted into the hole 10 is the holding force held by the connection terminal 6 and the pressing force of the pressure spring 3. Among these, the magnitude of the holding force at which the sealing plug 9 is held by the connection terminal 6 is the most likely factor, but in the case of the present invention, the area of the central part of the grommet that is bent and deformed by the internal pressure of the battery is sealed. It is much larger than the thickness (cross-sectional area) of the stopper, and a large force generated by the internal pressure applied to the central part of the grommet is applied to the small sealing stopper via the rod-shaped member 11. Therefore, the pressing force applied to the sealing plug via the rod-shaped member 11 is much larger than the holding force obtained by simply fitting the sealing plug to the through hole 10, so that the operating pressure of the valve opening is that of the sealing plug. The degree to which the holding force depends is small. Other factors greatly depend on the accuracy of the molding dimensions and mechanical processing dimensions of the member, but in the current processing, extremely high dimensional accuracy can be easily obtained with the current technology. As a result, a highly accurate valve opening operating pressure is achieved.

  The distance between the sealing plug 9 and the inner surface of the cap 1 depends on the insertion position when the sealing plug 9 is inserted into the through-hole 10, but as shown in FIG. Insert the end face so that it is flush with the inner end face of the connection terminal 6 or provide a step on the side of the sealing plug 9 as shown in FIG. By providing the above function, the insertion position of the sealing plug 9 can be easily made constant. Further, in order to prevent the cap 1 and the connection terminal 6 from being electrically short-circuited via the rod-shaped member 11, the rod-shaped member 11 is a hard synthetic resin product or a metal rod-shaped member is applied. Is arranged on the inner surface of the cap 1 with an electrically insulating material, for example, a synthetic resin film 16.

  In the first embodiment, the sealing plug is simply inserted into the inner end portion of the through hole provided in the connection terminal 6 by the insertion of the soft resin sealing plug, and the valve opening passes through the rod-shaped member 11. It is only inserted into the hole 10 and there is no process such as joining or pasting of members, and the assembly of the valve opening mechanism is extremely simple.

(Second Embodiment)
FIG. 2 is a diagram illustrating a second embodiment. In place of the sealing plug 9 of the first embodiment shown in FIG. 1, a sealing plug 9 'made of a synthetic resin film, a metal foil, or a laminate film of a synthetic resin film and a metal foil is attached to the outer end face of the connection terminal 6. By doing so, the outer end of the through hole 10 is hermetically sealed. A needle-like protrusion 11 'is arranged on the inner surface of the cap 1, and the valve-like member 11' is opened by penetrating the sealing plug 9 'when the internal pressure of the storage battery rises abnormally and the connection terminal 6 moves upward. . In the case of the second embodiment, a large force is not required when penetrating the sealing plug 9 ', and if the degree of bending of the grommet generated according to the internal pressure of the storage battery is stable, the pressure accuracy is high. Valve opening operation is possible. However, it is necessary to provide a rod-like member or needle-like member 11 ′ on the inner surface of the cap 1, or to attach a film-like sealing plug 9 ′ to the outer end face of the connection terminal 6, which is an assembly as compared with the first embodiment. Has the disadvantage of becoming complicated.

(Third embodiment)
FIG. 3 is a diagram illustrating a third embodiment. In place of the sealing plug 9 of the first embodiment shown in FIG. 1, a synthetic resin film such as polyester, a metal foil such as nickel or stainless steel, or a film of the synthetic resin film and a metal foil is formed on the inner end surface of the connection terminal 6. The inner end of the through hole 10 is hermetically sealed by sticking a sealing plug 9 ″ made of a film. A rod-like member 11 is disposed inside the through hole 10 as in the first embodiment. When the internal pressure rises abnormally and the connection terminal 6 moves upward, the rod-shaped member 11 opens by penetrating the sealing plug 9 ″. In the case of the third embodiment as well, a large force is not required when penetrating the sealing plug 9 ″, and if the degree of bending of the grommet generated according to the magnitude of the internal pressure of the storage battery is stable, the pressure accuracy is high. However, it is necessary to affix a film-like sealing plug 9 ″ to the outer end face of the connection terminal 6, and there is a drawback that the assembly is slightly complicated as compared with the first embodiment.

(Valve opening pressure investigation experiment)
30 AA-size sealed nickel-metal hydride storage batteries (example batteries) according to the first embodiment shown in FIG. 1 (a) and an AA-size sealed nickel-metal hydride storage battery according to the comparative example shown in FIG. (Comparative battery) 30 pieces were prepared. However, in this experiment, neither the example battery nor the comparative example battery is provided with the insulating film 15 for insulating the metal pressure spring 3 and the first terminal 7 of the pressure switch, and the cap 1 is interposed via the metal spring 3. And the first terminal 7 of the pressure switch are always electrically connected (the switch function of the pressure switch is stopped). In both the example battery and the comparative battery, the gasket 5 was a molded product of polypropylene. A through hole having a diameter of 4.0 mm was provided in the center of the grommet 5, and a connection terminal having a diameter of 4.3 mm was inserted through the through hole. In order to impart flexibility to the central part of the grommet 5, the thickness of the horizontal wall 5 'of the grommet 5 was set as thin as 0.8 mm. In the case of the comparative battery, three circular arc grooves having a V-shaped step surface, a depth of 0.5 mm, and a length of 4 mm were provided at equal intervals on the horizontal wall 5 ′ of the grommet 5. . On the other hand, in the example battery, a through hole 10 having a diameter of 2.3 mm was provided in the center of the columnar connection terminal 6. A polypropylene sealing plug 9 having a diameter of 2.5 mm and a length of 2 mm was inserted into the inner end of the through hole so that the inner end surface thereof was flush with the inner end surface of the connection terminal 6. A stainless rod member 11 having a diameter of 2 mm was inserted into the through hole. The distance between the sealing plug 9 and the inner surface of the cap 1 was set to 5 mm, and the length of the rod-shaped member 11 was set to 4 mm. Moreover, the polyester film was affixed on the inner surface of the cap of the example battery, and the contact between the cap 1 and the rod-shaped member 11 was cut off. The rated capacity of both the example battery and the comparative example battery was 2000 mAh.

  The example battery and the comparative battery in the fully charged state were charged at an ambient temperature of 20 ° C. at a constant current of 2 ItA until all the test batteries were opened, and the internal pressure of the storage battery was monitored during this time. The internal pressure of the battery when the valve was opened during charging was used as the operating pressure for opening the battery. FIG. 5 (a) is a histogram showing the distribution of the operating pressure for opening the valve of the example battery, and FIG. 5 (b) is a histogram showing the distribution of the operating pressure for opening the valve of the comparative example battery.

  When the AA size sealed storage battery sealed by the crimp seal is not provided with a valve opening mechanism, the crimp seal is normally destroyed (may cause explosion) when the internal pressure of the battery rises. The pressure is about 3 megapascals (MPa). As shown in FIG. 5 (a) and FIG. 5 (b), both the example battery and the comparative example battery are opened at a pressure of 2.5 MPa or less, and the crimp seal portion is destroyed. There was no. However, as shown in FIG. 5 (b), in the comparative battery, the valve opening operating pressure is distributed over a wide range of 1.6 to 2.5 MPa, and the opening of the example battery shown in FIG. The variation is larger than the distribution of valve operating pressure. The variation in the valve operating pressure of the comparative battery is large because, as mentioned above, it is difficult to keep the breaking strength of the grommet molded product constant, and because the stress is applied during battery assembly, the thin portion of the grommet breaks. Due to further changes in strength. On the other hand, in the storage battery according to the first embodiment, it is considered that a stable operating pressure is obtained because the valve opening operating pressure is determined by the dimensional accuracy of the valve constituent member that can be easily controlled.

  The operating pressure of the pressure switch can be set to any value by changing the pressing force of the pressurizing spring, the dimension of the horizontal wall of the grommet, etc., but if it is set low, the pressure switch will operate frequently during charging. The time during which the switch is off increases, and it becomes difficult to complete charging within a predetermined time. It is preferable to set the operating pressure of the pressure switch to 1.7 to 2 MPa so that the battery characteristics are not deteriorated and the charging is completed within a predetermined time. For example, when the operating pressure of the pressure switch is set to 1.7 MPa, in the comparative battery, one out of 30 batteries opens before the pressure switch operates. In the case of the battery of the example, the variation in the valve opening operating pressure is small, and in any battery, the valve opening operating pressure is larger than the operating pressure of the pressure switch.

  Further, in the case of the comparative battery, it is difficult to control the valve opening operating pressure and it is difficult to set the operating pressure to an arbitrary value. However, in the sealed storage battery according to the present invention, the dimensions of the valve constituent members By selecting, it is easy to set the valve opening operating pressure to an arbitrary value, and the degree of freedom in valve design can be expanded.

In the inventions according to claims 1 to 4, in comparison with the valve structure in which the conventional grommet is provided with a thin portion,
Since the variation in the release pressure of each battery can be reduced, there is no need to reduce the setting of the release pressure. Since it is obtained, the industrial applicability is extremely large.

It is a figure which shows the valve structure of the sealed storage battery which concerns on the 1st Embodiment of this invention. It is a figure which shows the valve structure of the sealed storage battery which concerns on the 2nd Embodiment of this invention. It is a figure which shows the valve structure of the sealed storage battery which concerns on the 3rd Embodiment of this invention. It is a figure which shows the valve structure of a comparative example battery. It is a histogram which shows distribution of the valve opening operation pressure of an Example battery and a comparative example battery.

Explanation of symbols

1 Cap 2 Second terminal of pressure switch 3 Pressure spring 5 Grommet 6 Connection terminal
7 Pressure switch first terminal 8 Gasket thin portion 9, 9 ', 9 "Seal plug 10 Through hole 11 Bar-shaped member

Claims (4)

In response to the internal pressure change of the storage battery at the time of charging, a sealed storage battery incorporating a current intermittent switch mechanism that cuts off or energizes the charging current,
A sealed storage battery comprising valve opening means for forming a through hole in a connection terminal that rises and falls due to a change in internal pressure of the storage battery when the internal pressure of the storage battery rises abnormally. The valve opening means
Sealing the inside or outside end of the through hole that communicates the inside and outside of the battery provided in the connection terminal with a sealing plug, and breaking or eliminating the sealing plug when the internal pressure of the storage battery rises abnormally The sealed storage battery according to claim 1, wherein: The valve opening means
A rod-shaped member disposed in the through-hole when the inner end of the through-hole communicating with the outside of the battery provided in the connection terminal is sealed with a sealing plug and the internal pressure of the storage battery rises abnormally The sealed storage battery according to claim 2, wherein the sealing plug is broken or eliminated by pressing the sealing plug. The valve opening means
A resin-like sealing plug is fitted to the inner end of the through hole that communicates the inside and outside of the battery provided in the connection terminal, and when the internal pressure of the storage battery rises abnormally, it is a rod that is placed in the through hole The sealed storage battery according to claim 3, wherein when the member presses the sealing plug, the resin sealing plug is pushed downward.

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