GB2056755A - Explosion proof storage battery - Google Patents

Abstract

The invention relates to an explosion proof storage battery (1) wherein the chamber (8) that divides the accumulator level from the cover (5) sealing the entire container (2) of the battery (1) is filled completely with an elastic insulating fluid, and wherein each inlet/outlet (3) of the battery (1) for the infeeding thereof and for the expulsion of the reaction gases therefrom is placed in communication with the outside via a pipe (9) that is insulated electrically with respect to the said cover, the lower part of which pipe (9) is hermetically secured to the said inlet/outlet (3) and the upper part to a corresponding filter (4), insulated with respect to the said cover (5). The cover (5) is provided with a pair of small apertures (11, 13) each provided with a plug (12, 14), one of which (11) is for injecting the said insulating fluid, and the other (13) is for evacuating externally, during the injection, any possible air bubbles. <IMAGE>

Description

SPECIFICATION Explosion proof storage battery The invention relates to an explosion proof storage battery, utilizable in particular as the motive force for the traction of movable means (for example, trucks) that operate in surroundings where the danger of explosions exists, such as quarries and mines, or where inflammable and explosive gases can develop.

As is known, use is currently made for traction purposes of storage batteries that have plates and are constituted by a container for the receptacles of the accumulators that are provided with corresponding open inlets/ outlets and communicate with a chamber located at a higher elevation which separates the upper level of the accumulators from a sealing cover.

The cover has arranged thereon a number of breather pipes in order to allow the reaction gases, including hydrogen, which is highly inflammable, that are expelled through the said outlets, during the normal operation of the battery (discharge), to be disseminated externally without the said chamber being placed under pressure.Furthermore, the said breather pipes comprise filters which allow the reaction gases to pass freely but prevent the propagation of a "flame" which can be generated as a result of an explosion of the gases localized inside the chamber should a spark be ignited for various reasons, the most frequent of which is that because of the battery being poorly maintained, or for other causes, one or more pairs of adjacent plates of opposite polarity remain dry whilst the battery is discharging, with a consequent deformation through heat of the said plate, until a reciprocal contact and a spark take place.

It is, therefore, very important for the plates not to remain dry and thus the maintenance of this type of battery has to be carried out very often, this being done via a plug with which the cover of the battery is provided.

The size of the said plug is close to that of the cover itself so as to allow easy access to the operator entrusted with the maintenance, to every important part of the battery.

With the above described type of battery there are a number of difficulties, the main one of which is due to the obligatory presence of the said chamber, in itself necessary, as stated above, in order to leave free access to the operator for the maintenance of the battery. This chamber, because of being saturated with inflammable gases (including hydrogen), causes possible explosions inside the chamber to be particularly violent, with a consequent irreparable damage of the battery itself.

Furthermore, this type of battery, of vast dimensions and weight is, since it is used for traction purposes, as stated, necessarily provided with an access plug of a large size (the weight of which is around 45 kilograms), the unscrewing, displacement and re-screwing on of which is certainly not easy.

The main object of the invention is to overcome the aforementioned difficulties through the construction of a battery with which it is possible to almost fully reduce the danger of explosions inside the battery itself and, in the very improbable event of such a thing occurring, to limit and damp the intensity thereof, the said battery contemporaneously achieving perfect insulation between the cover and the accumulators, with the consequential excellent electrical operation of the said battery.

Another object of the invention is to allow easy access to the battery on the part of the operator entrusted with the maintenance thereof, without the battery having to have an access plug, but without adversely affecting in any way the satisfactory electrical operation of the battery.

These and other objects too have been attained with the storage battery forming the subject of the invention, of the type comprising a container for the receptacles of the accumulators, provided with corresponding inlets/outlets that are there for the infeeding of the battery and for the expulsion of the reaction gases of the battery, above which there is a chamber that separates the accumulator level from a cover that seals the entire container, the said battery being of the type that utilizes filters, arranged on the said cover, provided to permit the dissemination externally of the reaction gases, and to prevent the propagation of a "flame" which can be generated as the result of an explosion of the reaction gases of the battery, essential features of the said battery being that the said chamber is filled completely with an elastic insulating fluid, each of the said inlets/outlets being placed in communication with the outside via a pipe insulated electrically with respect to the said cover, the lower part of which is fitted hermetically to the said inlet/ outlet, and the upper part to a corresponding filter, insulated with respect to the said cover, the latter provided, moreover, with a pair of small apertures, each fitted with a plug, one provided for the injection of the said insulat-.

ing fluid, and the other for evacuating externally, during the injection, any possible air bubbles.

With the said type of battery, by annulling the space available for reaction gases inside the said chamber and by channelling them compulsorily through the said pipes and the said filters directly to the outside, without the gases having the possibility of creating density phenomena, the probability of explosions occurring is reduced almost to zero. For such a thing to happen it would be necessary for a filter or for the evacuation of the gases via one of the aforementioned 'pipes to be obstructed, with the contemporaneous supposition of there also being a spark by contact of the plates in respect of the accumulator where the evacuation is obstructed As can easily be appreciated, it is extremely improbable that such events could occur contemporaneously.

In any case, even if they were to happen, since the space available for the reaction gases is greatly reduced and that it virtually coincides with the volume of a pipe, the explosion would be very reduced in intensity.

Furthermore, the effect of the explosion would be decisively damped on account of the presence of the fluid in the inside of the chamber which, in addition to being insulating, is elastic and thus acts as a cushion.

Besides the advantageous technical aspect described above, the invention in question also offers numerous other advantages of a practical nature. The possibility of direct action being taken from the outside for topping up the various accumulators, via the said pipes that communicate with the said filters and are identical in number to the inlets/outlets of the accumulators, and the spontaneous evacuation of the reaction gases, at the same time, make maintenance a lot more simple and faster than with the batteries known to date. Furthermore, the electrical operation of the battery is perfect, thanks to the excellent insulation between each inlet/outlet and the cover, to which the said elastic insulating fluid also contributes.

Further characteristics and advantages of the invention will emerge more obviously from the detailed description that follows of one preferred but not sole form of embodiment, illustrated purely as an unlimited example on the accompanying drawing, wherein a partial vertical section section of the storage battery in question is shown, with certain parts removed in order that others may be rendered more visible.

With reference to the above mentioned drawing, the storage battery in question (1) is constituted by a container (2) for the receptacles of the accumulators (R) which are provided with corresponding inlets/outlets (3) that are there for the infeeding of the battery and for the expulsion of the reaction gases of the battery, each one being connected to a corresponding filter (4) positioned on a cover (5) for sealing the entire container (2).

Each filter (4), of a known type, contains a number of separators (4a) supporting the filtering material (6) and is covered with an internally hollow plug (7). Filters of this type allow the dissemination to the outside of the reaction gases of the battery (which develop in a quantity that is not negligible during the "charging" of the battery, in which case the filter (4) is removed, and in a minimum quantity during the discharge of the battery) and contemporaneously prevent the propagation of a flame", due to eventual explosions, (in itself not very probable in the case in question), in order not to create the foundations for a much more violent and destructive explosion in the working surroundings.

A chamber (8) separates the accumulator level (L) from the cover (5). The said chamber (8) does not communicate with the outside, as instead happens in known cases and indeed in this particular instance it is each of the inlets/outlets that is placed in communication with the outside, via a pipe (9), the upper parts of which is fastened hermetically to the corresponding filter (4), and the lower part to the said inlet/outlet (3).

In this way it is possible to inject an elastic insulating fluid (10) into the inside of the space delimitated by the chamber (8), via a first small fluid inlet aperture (11) which is machined into the cover (5) and is provided with a plug (12). To overcome the problem of air bubbles which could form during the injection of the fluid (10), the cover (5) is provided with a second small air outlet aperture (1 3), which also has a plug (14), through which the air bubbles can pass freely during the injection of the fluid (10).

Each pipe (9) is fixed at the top to a body (15) for sustaining the corresponding filter (4), through the slotted in insertion of an elastic annular body (16), with which the upper extremity of the pipe (9) is integral, in a circular groove (17) machined in the lower part and in the inside of the said sustaining body (15).

The pipe (9) is, furthermore, hermetically inserted into the corresponding inlet/outlet (3) and, in fact, the lower extremity of the pipe (9) has a thickening (18) of the walls thereof, the outside diameter of which is greater than the inside diameter of the inlet/outlet-(3). In order to protect, render rigid and maintain the pipe (9) locked in position, externally thereto has been superposed a metal casing (19) whose longitudinal dimensions are slightly less than the part of the pipe (9) outside the inlet/outlet (3), and whose diameter is notably greater than that of the pipe (9) itself. In the hollow space in between the casing (19) and the pipe (9) there is an elastic element (20).

The upper part of the casing (19) is integral with the sustaining body (15), with the interposition of a small bushing, whilst the lower part is locked to the inlet/outlet (3). The said locking is achieved through the use of a first ring nut (22), in tight contact at the top with the casing (19), with the interposition of a bushing (23) integral with the casing (19) itself. The lower part of the said ring nut (22) engages with a second ring nut (24) which, in turn, engages with the inlet/outlet (3). Whilst engaging with the inlet/outlet (3) through the second ring nut (24), the first ring nut (22) is able to move axially with respect to the bush ing (23). In this way a certain snugging in the attachment of the casings (19) to their corresponding inlets/outlets (3), when the latter are not all of the same height (as often happens in practice), is possible.

The fact that the ring nut is not made in one single piece and that the first ring nut (22) engages with the inlet/outlet (3) concerned through a second ring nut (24), and the fact that the bushing (23) is provided with a lower protruding part (25), is due to problems solely of a constructional and an assembling nature. The ring nut (22) is thus independent of the dimensions of the inlets/ outlets (3) and this problem affects only the ring nut (24) which is easy to make and the dimensions of which conform to the various types of inlets/outlets (3). The task of the protruding part (25) is to prevent the withdrawal of the ring nut (22)-ring nut (24) assembly from the casing (19) during the positioning and the assembling of the said assembly.

Since the connection between the inlets/ outlets (3) and the corresponding filters (4) above them is also achieved through metal elements, this could lead to electrical conductivity between the accumulator group and the cover. To prevent such a possibility, each of the said sustaining bodies (15) of the filters (14), in direct metallic communication with the casing (19), is insulated from the cover (5). For this purpose, each body (15) is locked in position by an insulating bearing (26) supported by a pair of external elements, (27) and (28), respectively, not in contact with the body (15). The upper part of the innermost element (27) is flush with the lower surface of the bearing (26) and supports it.The said element (27) engages, externally, in the region of the lower part thereof, with the outermost element (28), which is in turn engaged, externally, with the cover (5) and constitutes an upper member flush with the top surface of the bearing (26). The maintaining in position, or the locking of each body (15) is, moreover, guaranteed by a ring nut (29) engaging, on the body (15)and placed in the lower part thereof, flush with the upper surface of the bearing (26) but not in contact with the elements (27) and (28).

The covering of each body (15), and thus of the corresponding filter (4), is guaranteed by a cap (30) fitted to the body (15) above the ring nut (29). Each cap (30) has, furthermore, at least one hole (31) whose purpose is to allow the said reaction gases to evacuate, and is kept locked, in a stable fashion, to the corresponding body (15) by means of a dowel pin (32).

With such a conformation of the upper group for each filter (4), the electrical conductivity between the inlet/outlet (3) and the cover (5) is inhibited completely due to the presence of the bearing (26) which supports the body (15). The positioning of the body (15) is, instead, guaranteed by the ring nut (29) and, eventually, by a circular protruding part (33) made peripherally on the body (15), with which the bearing (26) is flush.

The storage battery thus constituted, because of the reduced intensity of explosions in the inside thereof, can be reduced dimensionally with respect to the types known at present, with a consequential decrease in the weight of the battery.

Claims (5)

1. Explosion proof storage battery of the type comprising a container for the receptacles of the accumulators, provided with corresponding inlets/outlets that are there for the infeeding of the battery and for the expulsion of the reaction gases of the battery, above which there is a chamber that separates the accumulator level from a cover that seals the entire container, the said battery being of the type that utilizes filters, arranged on the said cover, provided to permit the dissemination externally of the reaction gases, and to prevent the propagation of a "flame" which can be generated as a result of an explosion of the reaction gases of the battery, essential features being that the said chamber is filled completely with an elastic insulating fluid, each inlet/outlet being placed in communication with the outside via a pipe insulated electrically with respect to the said cover, the lower part of which is fitted hermetically to the said inlet/outlet, and the upper part to a corresponding filter, insulated with respect to the said cover, the latter provided, moreover, with a pair of small apertures, each fitted with a plug, one provided for the injection of the said insulating fluid and the other for evacuating externally, during the injection, any possible air bubbles.

2. Storage battery according to Claim 1, wherein each pipe, internally made of rubber, is secured at the top to a body that sustains the corresponding filter, through the slotted in insertion of an elastic annular body with which the said pipe is integral, in a circular groove machined in the lower part and in the inside of the said sustaining body, the lower part of the said pipe being inserted hermetically into the said corresponding inlet/outlet,.

the lower part of the said pipe having a thickening of the walls thereof, the outside diameter of which is greater than the inside diameter of the said inlet/outlet.

3. Storage battery according to Claims 1 and 2, wherein each pipe is externally provided with a metal casing for protecting, rendering rigid, and locking it in position, the longitudinal dimensions of which are slightly less than the part of the said pipe that is outside the said inlet/outlet, and the diameter of which is notably greater than that of the said pipe, an elastic element being inserted in the hollow space in between the said casing and the said pipe in order to keep the said pipe guided with respect to the said casing, the top part of the latter being integral with the said sustaining body of the corresponding filter, and the lower part with the corresponding inlet/outlet, through locking means.

4. Storage battery according to Claim 3, wherein the said locking means are constituted by a ring nut, in tight contact at the top with the said casing, with the interposition of a bushing integral with the said casing, the axial dimensions of which are considerably greater than the similar dimensions of the contact surface of the said ring nut with the said bushing, the lower part of the said ring nut being engaged with the said inlet/outlet on which there is an external thread.

5. Storage battery according to Claim 2, wherein each of the said bodies for sustaining the filters is locked in position by an insulating bearing, supported by at least one external element, not in contact with the said sustaining body, that engages with the said cover, as well as by a ring nut engaging, on the said body and placed in the lower part thereof, flush with the said bearing but not in contact with the said external element, a cap for covering the said body being in engagement therewith, above the said ring nut and having at least one hole for the evacuation of the said reaction gases.