JPH06111798A - Explosion damping system and method to incorporate said system into storage battery - Google Patents

Abstract

PURPOSE: To provide an improve system to damp an explosion of a combustible gas accumulated in a head space of, especially, a storage battery. CONSTITUTION: A storage battery 10 comprises a porous, explosion damping material 26 installed in a head space of a storage battery case existing above electrode elements 18. The damping material 26 forms a layer or a lining on the inner side surface of the upper wall of the case, preferably, the inner side surface of upper end parts of respective side walls between the electrode elements 18 and the upper wall. The inside of the head space is left as being empty. Such an explosion damping material 26 is effective to limit the pressure increase caused by ignition of a gas in the inside of the case.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to batteries or cells, and more particularly to an improved system for damping the explosion of flammable gases that accumulate in the headspace of batteries.

[0002]

BACKGROUND OF THE INVENTION Many rechargeable batteries produce flammable gases during operation. Such gases are outgassed from the container of the accumulator into the environment or are recombined with active material in a secondary reaction within the accumulator. However, even in batteries that are prepared for internal recombination of flammable gases, there are operating environments in which the recombination mechanism is ineffective or significant amounts of flammable gases are produced. Combustible gases in the battery headspace can ignite accidentally and cause an explosion. The damage and injuries resulting from such an explosion are well documented. Therefore, for many years there has been a search for effective and practical means for preventing or minimizing the explosion and its danger in batteries.

The flammable gases produced in the battery, if not recombined efficiently, result in high internal pressures. To relieve this pressure, such gas needs to be vented to the atmosphere. Venting is typically a simple open vent slot or "burp valve (bu
rp valve), which is sometimes referred to as a "one-way relief valve." However, during degassing of flammable gas, an external ignition source, such as a flame or spark, near the battery vent vents the ignition. In turn, this can result in back propagation into the battery container, resulting in an explosion, so improvements in the relief valve structure and the development of flame arresters used in connection with vents will result in such protective devices being removed or unusable. Without being compromised, the rate of battery explosion caused by external ignition sources was significantly reduced, provided that the integrity of the container or cover was not otherwise compromised.

However, the external ignition source is one of the protective devices.
If it breaks through or ignites in the container, flammable gases in the headspace can explode. The gas concentration, which is typically a mixture of hydrogen and oxygen in lead acid batteries, and the relatively large headspace volume can result in an explosion that shatters the container, cover or other component. Furthermore, the explosion
Along with that, a liquid acid or other dangerous electrolyte is discharged from the container.

Therefore, there has been a long-felt need for materials and methods for suppressing or minimizing the effects of explosions in batteries. Eliminating the open headspace, or substantially filling it with solid material, would eliminate the possibility of explosion, simply by eliminating the presence of combustible gases. However, neither alternative is acceptable.
Open headspace is required in almost all batteries. The headspace houses certain essential storage battery components such as plate straps, inter-cell connectors or terminals. Further, in batteries that use free liquid electrolytes, which are sometimes referred to as "flooded" systems, the open headspace is to accommodate changes in the electrolyte level as the battery is cycled, Required to provide space for acid migration under extreme conditions of use such as overfilling due to misuse. The headspace also accommodates the movement of the electrolyte level when the battery is tilted during service so that the vehicle can be operated on the slope without loss of electrolyte. Due to the need to accommodate certain structural parts of the battery and to provide space for electrolyte level fluctuations, the headspace within the battery must be retained.

In order to prevent the explosion of the gas in the headspace and to extinguish any flame that may form, the headspace in the accumulator or cell is filled with a porous material, while the gas and the electrolyte are filled. It has long been known that can be moved through porous materials. For example, 1
Jensen US Patent No. 2,34, issued February 944
See No. 1,382. Other forms of explosion dampening materials have also been proposed. Evj, issued November 5, 1974
En U.S. Pat. No. 3,846,178 describes fitting closed cell foam pieces within the battery cover and between cells. More recently, commonly assigned patents provide explosive damping materials consisting of closely packed pillows made of fiber material such as foam or polypropylene. Binder et al., U.S. Pat. Nos. 4,751,154 and 4,751, issued June 14, 1988.
No. 155 and No. 4,85, issued August 22, 1989.
See No. 9,546. Lining the gas storage chamber of an electrochemical cell is described by Briggs et al.
U.S. Pat. No. 4,004,06 issued Jan. 18, 977
No. 7, but it is only intended to recondense the evaporated electrolyte.

Porous plastic materials are also used in fuel tanks or similar containers as a means to reduce the risk of explosion. For example, Allen, U.S. Pat. No. 3,561,639, issued Feb. 1971, Step.
US Pat. No. 3,650, issued Mar. 1977,
431, U.S. Pat. No. 4,141,460, issued to Funistric et al., February 1979, and Sheard.
Et al., U.S. Pat. No. 4,154,35, issued February 1979.
See issue 7.

A number of factors have been considered that generally impede the practical use of explosion decay techniques in batteries, including the production of other hazardous materials, manufacturing difficulties, and adverse effects on battery performance. it can. In particular, in the case of flooded batteries,
The actual loss of open headspace volume reduces the available space for electrolyte movement or electrolyte level changes.

It is known that fast charging or excessive overcharging can lead to severe gas generation in many types of accumulators, especially lead accumulators. If the bubbles formed in the electrolyte do not find a channel that is nearly perpendicular to the battery vent opening, the electrolyte may displace upward and overflow through the battery vent. This condition is known as electrolyte pumping. The damage and danger of the corrosive electrolyte spilled from the storage battery is clear.

Electrolyte pumping can occur even if the headspace of the storage battery is filled with a very highly porous material, ie a material with a high porosity. For example, an open or closed cell foam material can have a porosity as high as 97-98%, and when placed within the headspace of a battery, occupies about 2 or 3% of its total volume. However, in a full-storage battery, such a material can easily hold the electrolyte and does not force it back into the battery by gravity. The electrolytic solution thus retained in the porous filling material is easily pumped from the storage battery under the aforementioned vigorous gas generation conditions.

Further, if a relatively large amount of electrolyte is drawn from the cell by the wicking action of the porous material in the headspace, or if the porous material otherwise holds the electrolyte with which it is in contact. For example, insufficient electrolyte may remain in the cell for proper electrochemical reaction and battery operation.

In the explosion dampening material disclosed in the aforementioned Binder et al. Patent, certain materials that dampen explosions and extinguish flames resulting from the ignition of combustible gases work well in other aspects of battery operation. do not do. The impact of an explosion (at the peak pressure created in the open headspace of a battery) can be minimized by filling the headspace with a given type of porous material. The smaller the pore size of the damping material, the smaller the pressure created during an explosion. Unfortunately, however, the smaller pore size of the material increases the negative impact of the material on battery performance. This is because the smaller the pore size of the material, the more the material tends to suck up the electrolytic solution, that is, the tendency that the material retains the electrolytic solution in the pores and becomes wet with the electrolytic solution.

The absorbed electrolyte cannot return to the cell and can cause two serious problems. First
Moreover, the electrolyte solution retained in the porous material cannot be readily used for electrochemical reactions, thus reducing the electrical performance of the storage battery. Second, the retained electrolyte impedes the flow of gas produced in the battery, which results in the electrolyte being pumped from the battery through the vent opening in certain operating environments. The use of a compressed piece of explosive damping material and the filling of such a piece of material in the headspace makes the arrangement proposed in the Binder et al. Patent difficult to use. The present invention addresses these issues.

[0014]

The storage battery of the present invention comprises a storage battery case including a top wall, a bottom wall and a plurality of side walls, a plurality of electrode elements arranged in a container, and an electrolysis device in contact with the electrode elements. Liquid and a porous explosive damping material in the headspace of the case above the electrode element. The damping material forms a layer or lining on the inner surface of the upper wall of the case and preferably on the inner surface of the upper end of each outer sidewall of the container between the electrode element and the upper wall. There is. The rest of the headspace remains substantially empty. In contrast to the teaching of the earlier Binder et al. Patent, such explosion-damping materials are effective in limiting the pressure increase resulting from ignition of the gas in the vessel. This is a result of maintaining a continuous fit between the damping material and the outer casing. The vent for venting the gas generated by the electrochemical reaction inside the case can extend through the lining of the explosive damping material, eliminating the problem of electrolyte eruption when the damping material covers the vent is doing.

The present invention further provides a method of lining the interior of a storage battery headspace to provide the storage battery with an explosion-damping material.

[0016]

The present invention will be further described with reference to the accompanying drawings.

The present invention is based on the discovery that when the inner wall of the headspace of a storage battery is lined with an explosion-damping material, the explosion is adequately damped under most conditions even if the interior of the headspace remains empty. ing. This is quite unexpected in light of the conventional theory of how foam or fiber materials dampen hydrogen-oxygen explosions in batteries.

First, it was postulated that the chain reaction leading to an explosion, or at least an explosion, was terminated by recombination of the chain reaction initiator, in this case hydrogen atoms, to the surface. However, according to the present invention, such surface quenching was determined to be effective only at much lower pressures than were present in the headspace during the explosion. At atmospheric pressure, or higher pressures such as are present in the headspace during an explosion, hydrogen atoms are much more likely to collide with hydrogen or oxygen molecules than the material surface. Therefore, although experimental data suggest that this is not the case, surface area is no longer considered a significant factor.

Secondly, the aforementioned Binder et al. Patent is:
Although the material divides the headspace chamber into a number of small cells, which prevents rapid burnout,
Instead, it suggests creating a series of smaller bursts. This chain termination theory is in opposition to leaving most of the headspace open, as in the present invention. Incompatible with chain termination, but a substantially continuous, intimate contact between the damping material and the outer and top walls to be protected limits the fracturing of the end and top walls. Seems to be important first in terms.

The foam or fiber material is believed to play two different roles in damping. The presence of such a material creates a viscous resistance that (1) prevents the generation of high pressure waves, and (2) absorbs or destroys secondary (primary reflected) waves that coalesce to form high pressure or detonation waves. impose. A highly porous material with a porosity of about 85-95% can be seen as regularly spaced columns of columns offset or misaligned from each other. As the number and density of rows increases, the shock wave resistance increases and the pressure waves spread. As a result,
The impact on the wall spreads out over a longer period of time with progressively smaller amplitudes. With a slower rate of events, the forces exerted on the wall can be redistributed in the axial direction of the wall instead of being absorbed perpendicular to the wall by folding or breaking the container. The lining method of the present invention acts to dampen the explosion by creating viscous drag, absorbing secondary waves and thus preventing high pressure buildup.

Referring to FIGS. 1 and 2, the lead S of the present invention is shown.
The LI storage battery 10 includes a plastic storage battery case assembled from a container 12 and a cover 14. The container 12 and cover 14 are typically made of thin injection molded polypropylene. The container 12 is divided into a series of cells by parallel septums 16 that are spaced apart and integrally molded. Each cell comprises an electrode element 18, which is composed of alternating stacks of positive and negative plates spaced apart by separators, all in a manner well known in the art. The electrode elements 18 in each cell also include conventional lug and strap connectors (not shown). Adjacent electrode elements are connected in series through the cell partition 16 by the conductive inter-cell connector 19. The end cell of the storage battery 10 has a hole 20a.
At 20 includes a connection 20 to the external terminal through the cover 14. Cover 14 includes a series of vent / fill ports 22, one for each cell. The filling port 22 is closed by a vent cap assembly (not shown), but the vent cap assembly may be fixed or detachable.

In assembling a typical lead-acid battery having the above structure, the assembled electrode elements 18 are put in the cells of the storage battery, and the inter-cell connection between adjacent electrode elements is made through the partition wall 16 and further the terminals are connected. Connect. Next, the cover 14 is sealed in the container 12. Fill each cell with sulfuric acid electrolyte to a level just above the top of the electrode element 18. Then, the basic lead sulfate in the positive electrode plate and the negative electrode plate is electrochemically converted into lead dioxide and lead to form a storage battery. As mentioned above, except for the space occupied by the plate straps, inter-cell connector and terminal assembly, the electrode element 1
The head space H (FIGS. 3A and 3B) in each cell above the top of 8 and below the lower surface of the cover 14 is empty.

In such a conventional lead-acid battery, hydrogen gas and oxygen gas produced as a result of the electrochemical reaction in the cell move upward from the electrode element 18,
Cover 14 past flame arrestor or other vent structure
The gas accumulates in the headspace H until a positive pressure is established that is sufficient to vent the gas through the vent hole 22 at. Naturally the gas mixture is highly explosive,
The ignition of such gas accumulating in the open headspace results in an explosion that can easily shatter the container 12 and the cover 14, as well as other elements connected thereto. Besides the destruction of storage batteries, the dangers to humans that can occur from ruptured storage battery pieces and acid electrolytes are also well known.

According to the invention, the inner surface of the headspace H is lined with an explosive damping material 26. In the illustrated embodiment, the cover 14 is lined with a layer of explosive damping material 26a that is rectangular in shape. A substantially rectangular piece of damping material 26b is adhered to the upper end portion of the container along the side wall 21 and the end (shorter side) wall 23. Each piece of material 26b extends between adjacent partitions 16 or end walls 23 and covers the exposed portion of the corresponding side wall 21 above the cell element 18 to approximately the level of the container rim 25.
A pair of end material pieces 26c likewise line the exposed portion of the end wall 23. It is preferable to completely cover all exposed inner wall surfaces in the head space H. For example, a piece of material 26
If b and 26c are omitted and only layer 26a is used, the cover will remain intact in the event of an explosion, but the side walls and end walls of container 10 will often rupture.

In the illustrated embodiment, the material 26 is a polypropylene fiber batt having a thickness of about 0.25 to 1.5 inches, preferably 0.5 to 1.0 inches. The above thickness is preferred in current automotive lead acid battery applications. For other types and sizes of batteries, the thickness can be varied. In addition, the above-mentioned Binde
Provide sufficient protection to the container in the headspace H and the inner surface of the cover 14 without filling the headspace until electrolyte outflow and gas management are of concern as in the filling headspace of the r. et al. patent. To that end, the above thickness ranges are usually preferred for polypropylene and other materials described below.

The damping material 26 of the present invention is resistant to the electrolyte under the conditions typically encountered when using batteries, ie temperatures of -30 ° C to 60 ° C, and causes repeated ignitions in the battery headspace. Should maintain its structural integrity even after Further, the damping material 26 should be sulfuric acid resistant for use in lead acid batteries and should be sufficiently elastic to return to its original shape after compression strain. Generally, the dampening material should be capable of dampening explosions, but should have adequate chemical stability against dissolution or other degradation in the cell.

To this end, the damping material 26 is an open-cell or lofted fiber (l) made of polyalkylene, especially polypropylene and cross-linked polyethylene.
It is preferably composed of ofged fibers or glass fibers. Most preferred are needle-punched polypropylene fibers (cleaned and lubricant removed if necessary), melt-blown polypropylene fibers and polypropylene foam. Fibrous polypropylene is particularly well suited for a wide range of both acid and alkaline full battery systems. Polypropylene is stable and is substantially insoluble in the aqueous sulfuric acid solution used in lead acid batteries. In a filled alkaline system, which typically uses aqueous potassium hydroxide electrolyte, polypropylene is resistant to degradation. Therefore, while various air bubbles and fiber plastics are suitable for use as explosion-damping materials in lead-acid batteries, polypropylene is the best choice for use in acid and alkaline systems given their effectiveness, cost and stability. .

Instead of polypropylene, other materials such as glass fiber and open cell polyurethane foam may be used as the explosion dampening material 26. Polyethylene can also be used, but it does not work well in the high temperatures of the headspace environment.

The damping material 26 is typically used in an amount of from about 0.1 to about 5 ml per gram of fiber, most preferably from 1 to about 5 ml.
It is preferred to absorb and retain 4 ml of electrolyte. If the amount of electrolyte absorbed is in the latter range, the damping material can withstand repeated ignitions. In the dry state, that is, when the volatile liquid electrolyte is less than about 0.1 ml / g,
The damping material can only withstand one or two ignitions.

The fineness of a fiber of damping material affects the amount of electrolyte it holds. In particular, the material 26 preferably comprises a mixture of a first fine fiber and a second coarse (heavy) fiber. The first fiber has a fineness of about 5 to about 40 denier, and the second fiber is about 30 to about 120.
It preferably has a fineness of denier. Denier combinations are 15/30, 20/40, 25/50, 15
/ 60 and 20/80 are typical. The preferred fiber size range is 10 to 30 denier for fine fibers, especially 10 to 20 denier, and 30 to 100 denier for heavy fibers, especially 40 to 80 denier. Alternatively, the material 26 can be made of fibers having a uniform fineness of about 30-40 denier.

Heavy fibers and fine fibers are made of material 2
Preferably, they are substantially evenly interspersed with each other to form 6. The fine fibers enhance explosive damping and the heavy fibers allow for electrolyte drainage, but if the material 26 does not cover the open end of the vent / fill port 22, the latter becomes less important. The damping material typically consists of 10-90% by weight heavy fiber and 10-90% by weight fine fiber. About the same amount of mixture,
Thus, a mixture of 40-60 wt% heavy fiber and 40-60 wt% light fiber is most preferred. The density of the damping material is typically 10 for a uniform thickness of about 0.5 inch.
Within ~ 20 oz / square yard.

In the storage battery 10, the head space H in one cell is a cube of about 1.5 × 1.5 × 6.5 inches or about 14.6 inches. Headspace volume occupied by material 26 (porosity not considered)
Is 10% to 70%, especially 20 to 60%, most preferably 25 to 50% of this total. The unfilled interior space of the headspace reduces or eliminates the aforementioned problems caused by conventional damping aspects.

The damping material 26 is preferably adhered to the inner surface of the headspace H. Material pieces 26b, 2
6c usually remains in place without gluing if properly dimensioned, but when assembled or used, the strips of material 2
6b, 26c tend to pull away from the container wall.
If this happens, the uncoated part of the wall is prone to rupture during an explosion. Accordingly, the pieces of material 26b, 26c can be secured by any suitable means such as thermal bonding, ultrasonic vibration welding, adhesives and the like.

Layer 26a is similarly secured to the inner surface of cover 14. 2, 3a and 3b, the cover 14 is fitted onto the container 10 such that the inner surface of the cover 14 is adhered to the walls 21, 23 and the upper end of the partition 16. In the storage battery having this structure, the layer 26
The a is preferably secured to the cover 14 by selective gluing along a narrow outer perimeter zone 27 and a series of transverse crossbars 28 aligned with respect to the septum 16.
The thus pre-bonded layer 26a compresses polypropylene fibers as shown in FIG. 3A. Cover 1
4 is placed above the container 10 as in the normal assembly procedure and then glued to the container 10 at the rim 25 and the upper end of the septum 16. In this way, the areas 27, 2
When the fiber material within 8 fuses with the plastic of the container and cover, layer 26a becomes a series of elongated pillows 29 lining the top of the headspace in each cell.

FIG. 4 shows a blank 30 made of damping material 26 which can be used in place of the separate pieces of material 26a-26c. The blank 30 has six side flaps 3 on each side.
It is cut in the width direction at positions spaced so as to give 2. Similarly, the corners are notched to provide the end flaps 31 and holes 34 and 36 are provided for the terminal posts and vent / fill ports. Flap 31,
Folds or perforations 33 can be provided to facilitate folding of 32. When assembling the accumulator, the flaps 31, 32 are bent into the individual cells so as to cover the side walls and the end walls and are glued thereto if necessary. The cover 14 is then put in place and the storage battery is completed as described above.

To show the role of the dampening material 26 in reducing damage, a 1/4 inch thick polyurethane open cell foam (65 ppi) sheet 26 'is folded so that the folded portion of the foam is as shown in FIG. It was pushed into the headspace of each cell of the storage battery so that it abuts the cover. The amount of foam used (160 cc) did not fill the headspace (310 cc). Based on the explosive damping theory described above, little or no protection was expected when only about 50% of the headspace was filled. It is presumed that the unprotected end wall bursts, the pressure created is too high to be retained in the battery, and that multiple explosions result in extensive melting and burning of the foam surface. It was Normal electrolyte level, about 0.5 from plate
The results are summarized in Table 1 below, with levels on the inches or just enough to cover the plate.

[0037]

[Table 1] Surprisingly, the above results show that significant protection is obtained even with only a relatively small amount of damping material selectively placed in the battery. From further testing, 1 /
Explosion strength of 50 ~ with a thickness of 8 inches and a filling rate of 55%
It was found to be reduced by 67% and that the uncoated areas (especially the sidewalls) suffered a rupture in the event of an explosion.

A second series of tests have shown that the blast damping of the present invention can be further improved by adding impact modifiers to the cover. Rubber and polyurethane can be cited as examples of the impact absorbing material effective for the polypropylene storage battery container and the cover. In these examples, the cover was a 50/50 mixture of polyurethane and RAO-61. In Samples 1-4, 0.5 inch thick needle-punched polyurethane strips (50/50 blend of 15/60 denier fibers) were placed inside the side walls of the cover and container above the plate as shown in FIG. Fixed to. In Samples 5-7, only the inner surface of the cover was coated and the insert to protect the sidewalls was omitted. In addition, the container in these three samples was a 75/25 mixture of polyurethane and RAO-61. Comparative Examples 8-13 were prepared by filling the headspace of a storage battery with 14 g of the same needle-punched polyurethane (15/60 denier) per cell according to the method of US Pat. No. 4,751,154 to Binder et al. The results are as follows.

[0039]

[Table 2] The above results showed that, with the impact of the cover mitigated, the protection afforded by the method of the present invention is comparable to conventional methods that require complete headspace filling.

The present invention provides other benefits because it typically has less interference with headspace operation. For example, since the cell structure is not tightly packed, there is adequate space to allow for tilt, acid fill and overcharge. Battery performance is not affected by the presence of the damping material. Manufacturing and assembly are simplified and the economy is increased by using less material.

The damping material described herein has been described for use in batteries having a full electrolyte system, either acid or alkaline. Examples include nickel-zinc, lead-acid, nickel-cadmium, and hydrogen-nickel storage batteries. However, various accumulators have fixed gel electrolytes or so-called "starved" electrolytes.
d) "Operates with an electrolyte system. Hydrogen and oxygen gases can be generated when forming such batteries and in abnormal operating environments such as overcharging due to inadvertent or misuse. In batteries using acid electrolytes, oxygen recombination is typically slower than true recombination systems, and hydrogen is produced more rapidly even under open circuit conditions. The explosion damping system of the invention is also effective in a non-full liquid system.

The damping material of the present invention was developed on October 1, 1990.
Ordinary transfer of 6-day application Hydrostatic electrolyte pump (hydrostatic) described in US Pat. No. 4,963,444.
It can also be used in a storage battery provided with an electrolyte pump), the entire disclosure of said patent being hereby incorporated by reference. The filled headspace reduces the effectiveness of the hydrostatic pump. The storage battery of the present invention is particularly effective for electric drive vehicles. Many electric vehicles are designed to require a large number of batteries, increasing the risk of explosion. In certain battery applications, it may be desirable to use open cell foam in certain areas of the battery and closed cell foam in other areas.

While some embodiments of the present invention have been described herein, such description and drawings are for purposes of illustration and the invention is limited only by the claims.

[Brief description of drawings]

FIG. 1 is a plan view of the storage battery of the present invention with a cover removed.

2 is a bottom view of a cover of the present invention that fits on the storage battery shown in FIG. 1. FIG.

3A is a line segment 3 of FIG. 2 before being incorporated into the storage battery of FIG.
FIG. 3 is a longitudinal cross-sectional view taken along line -3.

3B is a longitudinal cross-sectional view taken along the line segment 3-3 of FIG. 2 after being incorporated into the storage battery of FIG.

FIG. 4 is a plan view of an insert made of an explosion-damping material according to the present invention.

FIG. 5 is a partial cross-sectional view of the headspace of a storage battery filled with another insert of the present invention.

[Explanation of symbols]

 10 Lead acid battery, 12 container, 14 cover, 16 partition wall, 18 electrode element, 26a, 26b, 26c Explosion damping material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Lichyard Earl D'Abriille Binder United States, Wisconsin 53051, Menomonie Foalls, Tamaratsk Trail N 7918 D'Abriille 164 (72) Inventor Daniel Jeiei Canteillon United States, Wisconsin 53089, Sassex, Mica Road N 73 Dubrille 24881 (72) Inventor Allen Sea Cheapman United States, Wisconsin 53224, Milwaukee, North One Handled and Sixth Streets 8231 (72) Inventor Guy D. McDonald, Wisconsin 53211, United States, Schioautud, North Marl Borrow Drive 4354 (72) Inventor Brian El Matsukiny Wisconsin 53211 United States, Wisconsin 53211, Schyoautud, North Utdburn 4312 (72) Inventor Zyon Newman United States, California 94708, Kennington, York Avenyu 114 (72) Inventor Lichyard Sea Stone, Wisconsin 53224, Milwalk, West Wabatushyu 10603, USA

Claims (10)

[Claims] 1. A case including an upper wall, a bottom wall and a side wall, a plurality of electrode elements arranged in the case, an electrolytic solution in contact with the electrodes in the case, and in the case A vent for degassing the gas produced by the electrochemical reaction of, and a porous explosive damping material arranged in the headspace of the case above the electrode element, the venting of the gas in the case A storage battery comprising a material effective to limit pressure build-up resulting from ignition, the material comprising: each of said material on an inner surface of an upper wall of said case and between said electrode element and said upper wall. A storage battery having a lining formed on the inner surface of the upper end of the side wall such that the remainder of the headspace remains substantially empty. 2. The accumulator of claim 1, wherein the damping material comprises a fiber bat. 3. The storage battery according to claim 2, wherein the fiber is made of polypropylene. 4. The storage battery according to claim 1, wherein the storage battery is a lead storage battery. 5. The storage battery of claim 1, further comprising means for adhering the damping material to the top and side walls. 6. The damping material has a thickness of 0.25 to 1.5 inches and 10 to 10 of the headspace.
Occupies 70%, and therefore 30% of the headspace
The storage battery according to claim 1, wherein ˜90% does not include the material. 7. The damping material has a thickness of 0.5-1 inch and 20-60% of the headspace.
Occupying 40-80% of the headspace
The storage battery according to claim 1, wherein% does not include the material. 8. A method of introducing a lining of explosion-damping material into a storage battery of the type having a substantially closed case including a case and a cover fitted over an open upper end of the case, said method comprising: The cover has an inner surface forming a top wall of the case, the case having a bottom wall, a side wall, and a series of internal partition walls spaced to define a series of cells. A head space between the electrode element and the cover, and a pair of external terminals, and a layer of explosive damping material on the cover. Fixed to the inner surface, a piece of explosion-damping material fixed on each side wall, over the adjacent cell partition above the electrode element, such that the headspace is lined with the explosion-damping material. A method comprising fixing a cover to the case. 9. The method of claim 8, wherein the material is polypropylene fiber. 10. The step of securing the layer of material further comprises adhering the layer to the inner surface along its outer periphery and a series of spaced stiles to secure the cover. Further adhering the inner surface and the layer of explosive damping material to the upper end of each partition along the cross bar and to the upper end of each partition along the outer periphery. 9. The method of claim 8 including.