GB2086646A

GB2086646A - Vent valves for batteries

Info

Publication number: GB2086646A
Application number: GB8129121A
Authority: GB
Original assignee: Chloride Group Ltd
Current assignee: Chloride Group Ltd
Priority date: 1980-09-25
Filing date: 1981-09-25
Publication date: 1982-05-12

Abstract

This invention is a vent valve suitable for an electric storage battery in which a movable valve member 16 co-operating with a valve seat 14 is caused to move by being attached to or integral with a rubber annulus 19 one side of which is exposed to ambient pressure while the other side is exposed to the pressure within the battery. The area of the annulus 19 is substantial compared with the size of the valve member so that a small pressure difference across it can be sufficient to open the vent. Alternatively (Fig. 7) a corrugated annulus 19 may be provided which forms a seal with a post 42 depending from a closure 23. Motion of the annulus under influence of pressure causes the inner edge to encounter recesses 43, allowing escape of gas past the annulus. In a further embodiment (Fig. 9) a flexible disc 19 seals against shoulder 116 and unseals when the disc 19 distorts under the influence of pressure. <IMAGE>

Description

SPECIFICATION Vent for electric storage battery This invention relates to vents for electric storage batteries, for example, sealed combination batteries in which there is little or no free liquid electrolyte, so-called drain-dry batteries which are charged and emptied of electrolyte for storage, and dry charged batteries.

In recombination batteries in particular, there is often a requirement that a normally closed vent valve should be capable of opening to release gas even if the pressure difference with the battery above ambient pressure is quite low, while yet there must be no possibility of air entering the battery from outside.

According to the present invention a vent valve suitable for an electric storage battery comprises a valve member normally closing a vent and an elastomeric component having a substantial area normally in communication with a space upstream of the vent and arranged when the pressure to which the substantial area is exposed is above a certain pressure to cause the valve member to move to allow fluid in the space to pass through the vent.

The vent valve can be formed in the lid of a battery or can be formed as part of a separate vent plug for screwing or force fitting into an opening in the lid of a battery.

In a preferred form of the invention the elastomeric component is constituted by an external flange on the valve member and the battery lid has a tubular surface in relation to which the valve member which is in the form of a tube can move to open and close the vent after which gas can pass through the tube.

The provision of the upstream space, one wall of which is provided by a substantial area of the elastomeric component which carries the movable valve member enables a very small pressure difference across the elastomeric component to be sufficient to move the valve member and open the vent.

The invention may be carried into practice in various ways and certain embodiments will now be described by way of example with reference to the accompanying drawings each of which is a perspective view of one half of a vent valve formed in the lid of a sealed recombination electric storage battery.

As shown in Fig. 1 the lid 11 of the battery is formed with a well 12 having at the centre of its bottom wall 13 a cylindrical depression 14 defining a valve seat as the cylindrical inner surface of the depression which is continuous through its lower half and has grooves 15 in its upper half.

The valve seat co-operates with a valve member constituted by the external edge 16 of a flange 17 at the bottom of a tubular component 18 formed integrally with a rubber annular disc 19 positioned with the well 12 and located around its outer edge between an upstanding rim 21 from the base 13 and a depending rim 22 on a valve closure 23 which itself is a snap fit in the top of the well flush with the upper surface of the lid 11.

The bottom 13 of the well has a number of openings 24 which put the space between the upper surface of the bottom 13 and the lower surface of the annulus 19 in communication with the interior of the battery shown generally at 25. That space, indicated at 26, is upstream of the vent defined between the valve seat 14 and the valve member 16.

A VYON (registered trade mark), or other, porous disc 27 is fitted within the valve closure 23 and restricts the free flow of gas between the upper side of the annulus 19 and the atmosphere although its porosity permits gas to escape slowly.

Thus the pressure at the upper side of the annulus 19 will be atmospheric pressure and if the pressure within the battery acting in the upstream space against the underside of the annulus 19 increases above atmospheric pressure by more than a predetermined amount the annulus 19 will deflect upward sufficiently for the valve member 16 to move into the region of the valve seat containing the grooves 15 to enable gas in the upstream chamber 26 to pass around the edge of the valve member 16 and up the tube 18 for passage through the porous disc 17 and through restricted vent holes 28 in the closure 23 to atmosphere.

The very substantial area of the annulus 19 which is subjected to that pressure difference, means that a very slight pressure difference can be sufficient to open the valve and the position of the valve member at which the vent opens can be precisely determined.

Figure 1 shows how the annulus 19 has a thicker external rim 29 where it is clamped between the rims 21 and 22, and in general the annulus can be designed in accordance with the desired release pressure and the dimension of the parts of the lid 11.

For example the annulus 19 may be of corrugated form whether the corrogations are annular or radial.

Figure 2 shows a variation of Fig. 1 in that the outer edge of the annulus 19 is formed with a depending hooked rim 31 which engages an external hook on the edge 21 formed on the well bottom 13. In that embodiment the porous disc 27 is omitted but the upper surface of the annulus 19 has a number of castellations 32 in a spaced ring around the top of the tube 18 to prevent the top of the tube becoming blocked by contact with the under surface of the closure 23.

Figure 3 shows how instead of having the castellations 32, the upper surface of the annulus can extend over the top of the tube 18 with a central aperture and four radial slots so that once again the top of the tube 18 cannot be closed by contact with the top of the annulus 19 with the underside of the closure 23.

In Figure 4 the only difference is that the annulus 19 is fixed in position by having its outer edge 35 fitted in a corresponding inter ;7awl annular groove in the well 12.

Figure 5 shows a variation in which the valve is a two way valve that is to say one which can operate if the pressure in the upstream chamber 26 becomes below atmospheric pressure by a predetermined amount.

In those circumstances of course the annulus 19 will deflect downwardly and the valve member 16 will then come into contact with a spaced ring of internal radial projections 38 to allow air to flow around the valve member into the upstream chamber 26 and hence into the top of the battery compartment to rebalance the pressures.

The variation of Figure 6 has the valve seat as the inner edge of an inwardly extending radial ring 39 on the inner surface of the depression 14 whereas the valve member is constituted by an external ring 41 on the tube 18 integral with the annulus 19. In the undeflected position of the annulus 19 and the valve member 41 is in contact with the seat 39 and the vent is closed but deformation of the annulus either up or down moves the valve member 41 clear of the valve seat 39 to open the vent.

In Figure 7the valve seat is constituted by the external cylindrical surface of a post 42 depending from the valve closure 23 and the valve member is constituted by the inner edge of the annulus 19 which is of corrugated form.

In the undeflected position the inner edge of the diaphragm is in sealing contact with the surface 42 and the vent is closed but deformation of the annulus up or down brings its inner edge into line with one or other of a pair of rings of recesses 43 in the surface 42 so that gas can flow around the edge of the annulus through the recesses.

That embodiment does not have a perforated disc 27 but in the variation of Figure 8 there is a perforated disc 45 seated in a corresponding recess in the closure 23 and communicating with the top of a central bore 44 in the depending cylindrical member 42 which bore is in communication with the bottoms of the recesses 43.

In all the embodiments there is a space 26 between the openings 24 and the vent which space has one wall constituted by the annulus 19 of substantial area so that a small difference in pressure across the annulus can be sufficient to move the valve member to open or close the vent.

In Figure 9 the well 12 has in its bottom wall an opening 113 which is in four segments separated by radial bars 114. Upstanding around the opening 113 is a wall 115 terminating in a rounded shoulder 116 with a radius of 1.0 millimeters. A disc 19 of ethylene propylene closed cell elastomer 2 millimeters thick, sits on the rounded shoulder 116 surounding the opening 113, and is normally a snug fit within the well 12. However, when a valve closure member 23 is snap fitted into the top of the well, a depending post 118 on the closure slightly deforms the disc annulus 19 so that it is partly wrapped around the rounded shoulder to effect a good closure. The closure has a number of fine holes 28 for the escape of hydrogen which passes the valve member when the gaseous pressure inside the lid 11 is slightly above ambient pressure.

The ethylene propylene polymer is sufficiently elastomeric to deform in response to a low pressure difference and allow the escape of the hydrogen while yet it is not attacked by sulphuric acid to become tacky so that it does not tend to stick to the rounded shoulder 116. Moreover provided that any partlyclosed cells at the closure surface of the disc are filled, for example with petroleum jelly so that the surface is smooth, then, in the absence of any excess pressure within the battery, valve member makes an effective seal all around the rounded shoulder to prevent the entry of air.

Claims

1. A vent valve suitable for an electric storage battery comprising a valve member normally closing a vent and an elastomeric component having a substantial area normally in communication with a space upstream of the vent and arranged when the pressure to which the substantial area is exposed is above a certain pressure to cause the valve member to move to allow fluid in the space to pass through the vent.

2. A vent valve as claimed in Claim 1 in which the valve member and the elastomeric component are together contituted by a disc one part of which closes the vent while the other part is exposed to the upstream space.

3. A vent valve as claimed in Claim 1 in which the elastomeric component is constituted by an external flange on the valve member.

4. A vent valve as claimed in Claim 3 in which the flange is located around its outer edge and connected to the valve member at its inner edge.

5. A vent valve as claimed in any of the preceding claims including a porous disc downstream of the vent.

6. A vent valve as claimed in any of the preceding claims including a valve closure downstream of the vent and downstream of the porous disc, if any, which valve closure has restricted openings for the escape of the fluid which has passed through the vent.

7. A vent valve as claimed in any of the preceding claims mounted on a battery lid which has means defining a gas chamber which chamber has a part co-operating with the valve member at the vent.

8. A vent valve as claimed in Claim 7 in which the elastomeric component extends across the escape chamber so that one side is at ambient pressure and the other side defines the said upstream space as a part of the escape chamber, which upstream space is in communication with the interior of the battery.

9. A vent valve as claimed in Claim 8 in which the battery lid has a tubular surface in relation to which the valve member can move to open and close the vent.

10. A vent valve as claimed in Claim 9 in which the tubular surface has interruptions or irregularities defining the vent and past which gas can flow when the elastomeric component moves the valve member.

11. A vent valve as claimed in any of the preceding claims in which the elastomeric component is an annular disc of corrogated form.

12. A vent valve as claimed in any of the preceding claims in which the valve member is in the form of a tube positioned with the elastomeric component and through which gas passing the vent also passes.

13. A vent valve as claimed in Claim 12 including stop means or the like for preventing the tube being blocked when the elastomeric component is moved excessively.

14. A vent valve as claimed in any of the claims 1 to 8 in which the valve member is constituted by the inner edge of the elastomeric component which is of annular form, which valve member is normally in contact with the surface of a fixed post but which when the elastomeric component is deflected moves into relationship with discontinuities in the post constituting the vent.

15. A vent valve suitable for an electric storage battery and constructed and arranged substantially as herein specifically described with reference to any figure of the accompanying drawings.

16. A vent valve as claimed in any of the preceding claims integral with, or fitted into, the lid of a recombination or other electric storage battery.

1 7. A vent valve as claimed in any of Claims 1 to 15 formed in a vent plug suitable for fitting removably into an opening in a lid of an electric storage battery.