Relief valve

A relief valve (60) for a liquid container, the valve comprising a substantially conical body (50) extending into the container, and tapering inwardly away from an external wall of the container, at least one air inlet passage (62) through the substantially conical body; and a flexible diaphragm (53) extending over the conical body, being attached at its outer periphery around the substantially conical body and having a central opening surrounding the substantially conical body above the air inlet passage so as to seal the air inlet passage until the pressure within the container falls below a predetermined level.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a US National Stage of International Application No. PCT/GB2009/002672, filed 16 Nov. 2009, which claims the benefit of GB 0820978.5, filed 17 Nov. 2008, both herein fully incorporated by reference.

FIELD OF THE INVENTION

The present invention is directed to a relief valve.

BRIEF SUMMARY OF THE INVENTION

In particular, the invention is directed to a relief valve for a dispenser which dispenses liquid soap or the like. In such a dispenser, as the liquid is dispensed from the container, the pressure within the container drops. Once the pressure drops below a certain level, air would be drawn in through the liquid outlet, thereby interfering with the outlet flow.

To prevent this, a separate pressure relief valve is provided to allow air into the container once the pressure within the container drops below a certain level.

It is known to make such check valves from an elastomeric material with a slit. Such a valve is disclosed in WO 00/27746. The relief valve is intended to be used with the container in an inverted configuration. It is convenient for the relief valve to be in the cap of the container as the main part of the container is a simple molding without complex parts. However, in an inverted configuration, the weight of the liquid bears on the relief valve if it is within the cap. A slit elastomeric valve therefore has to be robust enough to withstand this, but, at the same time, must be able to open reliably when the pressure within the container drops below a certain level.

The present invention aims to provide a pressure relief valve that can operate well in the cap of a container when the container is in an inverted configuration with the cap lowermost. At the same time, the valve should be simple in structure and suited to mass production.

According to the present invention, there is provided a relief valve for a liquid container, the valve comprising a substantially conical body extending into the container, and tapering inwardly away from an external wall of the container, at least one air inlet passage through the substantially conical body; and a flexible diaphragm extending over the conical body, being attached at its outer periphery around the substantially conical body and having a central opening surrounding the substantially conical body above the air inlet passage so as to seal the air inlet passage until the pressure within the container falls below a predetermined level.

The substantially conical body with the air inlet passage can simply be part of the molding of the underlying container. All that is then required is the flexible diaphragm which can readily be fitted in place.

The conical body supports the diaphragm, and the weight of the liquid in the container only serves to enhance the seal under normal circumstances. Because of the underlying support, the diaphragm material can be made very thin as the material itself does not need to support the weight of the liquid without buckling. This thin diaphragm layer is then readily displaceable by the incoming air when the pressure within the container drops.

The diaphragm may seal against the wall of the conical body itself. In this case, if the angle of inclination of the diaphragm is less than the angle of inclination of the conical body, this creates a natural biasing force to hold the diaphragm on the body.

However, preferably, a cylindrical post is upstanding from the conical body and the central opening in the flexible diaphragm is a tight fit against the post to form the seal. This forms a more positive and more easily repeatable seal than sealing against the conical body itself.

The relief valve is preferably applied to a container having a cap and a bottle, the container having an outlet in the cap and being arranged to dispense liquid from the container when in an inverted configuration, the relief valve being in the cap.

Preferably, the liquid container has an outlet valve to control the flow of liquid out of the container. In this case, the flexible diaphragm is preferably integral with the outlet valve. If the outlet valve is resiliently biased by biasing elements these are also preferably integral with the diaphragm and the outlet valve. This simplifies the structure of the relief valve as the flexible diaphragm can effectively be molded into an existing component rather than being a separate component in its own right.

As mentioned above, the relief valve is designed to prevent air from entering through a liquid outlet, as this disrupts the liquid flow and does not dispense the desired dose. A refill unit for dispensing a liquid designed to be used in a inverted configuration, with the outlet at its lowermost end, will typically comprise a bottle forming the main body of the unit with a cap at its lowermost end. In such a unit, it is desirable to place the outlet and the relief valve in the cap. This allows the bottle to be formed as a simple molding such as a blow molding, while the cap can be a more complex molding comprising a number of pieces. However, this brings the relief valve into close proximity to the outlet thereby reintroducing the possibility of incoming air being entrained in the outgoing liquid and disrupting the flow. This imposes limitations on the placing of the outlet and relief valve and also means that the diameter of the cap must be reasonably large in order to provide adequate separation between the outlet and the relief valve.

According to a second aspect of the present invention, a refill unit for a dispenser has a cap at one end which, in use, is the lowermost end, an outlet in the cap with an outlet valve and associated valve seat for allowing selective dispensing of liquid from the unit, a pressure relief valve within the cap for allowing air to enter the unit if the internal pressure drops below a certain level, and a shroud in the form of a wall surrounding at least the side of the pressure relief valve facing the outlet and extending to a location above the valve seat when the unit is in its usual orientation with the cap at the lowermost end.

The shroud prevents there being a direct path for the incoming air to the liquid outlet, thereby allowing the relief valve to be positioned closer to the outlet valve. This allows greater flexibility of the positioning of the relief valve and the outlet, and allows the cap to be reduced in size.

There may be a single relief valve, or there may be more than one relief valve. If there is more than one relief valve, each pressure relief valve is associated with a shroud in the form of a wall surrounding at least the side of the pressure relief valve facing the outlet and extending to a location above the valve seat when the unit is in its usual orientation with the cap at the lowermost end.

The pressure relief valve preferably comprises a resilient component which is deformable when the internal pressure drops below the certain level, the resilient component being attached to the cap by being sandwiched between the cap and a fixing plate, wherein the shroud is provided in the fixing plate.

The resilient component is preferably integral with the outlet valve. The outlet valve may be biased by biasing elements, which may also be integral with the outlet valve and resilient component.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The dispenser is a hands-free dispenser which is generally suitable for domestic use. The dispenser is primarily intended to dispense liquid soap, but may also be used to dispense other liquid or semi-liquid products (ideally with a viscosity greater than water), such as hand cream, body lotion, moisturiser, face cream, shampoo, shower gel, foaming hand wash, shaving cream, washing up liquid, toothpaste or a sanitising agent such as alcohol gel.

The dispenser comprises two main parts, namely a refill1and a base unit2. The refill1provides a reservoir of liquid to be dispensed and is fitted to the base unit2as set out below.

The base has an interface3into which liquid is dispensed from the refill unit. The interface3is in fluid communication with a dispensing tube4. A pump5is selectively operable to pump a metered dose of the liquid along dispensing tube4and out of dispensing head6.

The base has an infrared transmitter7A which transmits an infrared beam through a window8to a receiver7B to sense the presence of a user's hands in the vicinity of the dispenser. Control circuitry reacts to a signal from the proximity sensor to activate the pump. The illustrated sensor is a break beam sensor, but may also be a reflective sensor. Although an infrared sensor is shown, any known proximity sensor such as a capacitive sensor may be used. The device may be mains powered or battery powered. Alternatively, it may be a manually operated pump device in which a user pushes a lever to displace the product.

The interface between the refill1and base unit2will now be described in greater detail with reference toFIGS. 2 to 10.

The base unit2comprises a cowling10which forms a cup-shaped housing surrounding a significant portion of the refill to protect and support it. A spigot11projects through the base of the cowling10and is sealed to the cowling10by an O-ring seal12. The spigot has a plurality of castellations13in its top surface. A second O-ring seal14surrounds the spigot11beneath the castellations13.

The refill1comprises a bottle20to which a cap21is fixed. The bottle20has a neck22which fits over and seals with an annular flange23within the cap21. The cap21has an upwardly depending skirt24(when in the inverted orientation shown in the drawings) which forms the outer surface of the cap. Working inwardly from the skirt24, the next feature of the cap is an outer annular wall25which is generally co-axial with the skirt24.

This is shown in detail inFIGS. 5 to 10.

The outer annular wall25consists of a pair of retaining members26and a pair of support members27which alternate with one another and each extend for approximately a quarter of the circle as shown inFIGS. 5,6,8and10. The profile of the support members27is as shown inFIG. 2. These members extend directly up from the lower wall of the cap, are parallel sided and have an inclined upper surface28. The profile of the retaining members26is shown inFIGS. 7 and 9. Unlike the support members27, these are not fixed to the wall of the cap. Instead, they are fixed at either end to the support members27by frangible members29as best shown inFIGS. 6 and 8. The retaining members26are parallel sided and have an inclined upper surface35as shown inFIGS. 7 and 9.

As shown inFIGS. 7 and 9, the neck22of the bottle has an inclined outer surface36which is complimentary to the inclined surfaces28and35of the annular wall25. Behind the inclined outer surface36is a shoulder37which faces the main body of the bottle20. This inclined outer surface36and shoulder37is only present in the vicinity of the retaining members26and not in the vicinity of the support members27. Adjacent to the support members27, the neck22has a parallel sided configuration as shown inFIG. 2.

In order to insert the bottle20into the cap21, the bottle20is pushed down with its neck fitting over the annular flange23. The inclined outer surface36of the bottle co-operates with the inclined surfaces28,35to displace the retaining members26radially outwardly until the shoulder37snaps into place behind the retaining members26as shown inFIG. 7. When the bottle20is pulled off of the cap21, the shoulders37bear against the retaining members26, thereby breaking frangible members29so that the retaining members26become detached from the cap21as shown inFIGS. 9 and 10. Once this has happened, it is no longer possible to retain the cap on a bottle, thereby preventing subsequent use of the refill1.

It should be noted that it is not necessary for both of the retaining members26to become fully detached from the lid. It is possible that only one of these becomes detached, or that one or both are simply displaced to a location at which they can no longer engage with the neck of the bottle.

Returning now toFIGS. 2 to 4, the liquid outlet and associated valve will now be described.

The liquid outlet from the reservoir is provided by an annular wall30surrounding a central opening31. At the top of the annular wall30is an inclined surface32(seeFIG. 4) which provides a valve seat for outlet valve element33. This is shown in the form of a U-shape cup-like member, but may equally be a solid member or a hollow ball-like member. The outlet valve element33is biased into its closed position by a plurality of biasing elements34. These are attached at their upper end towards the top of the valve element33and are attached at their lower ends at a location radially outward of the annular wall30and below the top of the annular wall30. They are preferably formed integrally with the valve element33.

As shown inFIGS. 2 to 4, when the refill1is lowered into the base unit2, the spigot11engages with the lower surface of the valve element33as shown inFIG. 3. Further downward movement of the refill causes the valve element33to be lifted from its seat, and also brings the O-ring14into sealing engagement with the annular wall30. The valve element33is lifted to the position shown inFIG. 4. In this position, liquid in the bottle20can flow around the biasing elements34, and enter the spigot via the castellations13and hence flow into the base unit2. Liquid is prevented from escaping between the spigot11and annular wall30by the O-ring seal14. This arrangement offers a simple and mess-free way for a consumer to insert a refill regardless of the fill level of the refill.

In order to remove a refill, the consumer lifts it out of the base whereupon the biasing elements34cause the valve element33to return to the seat32. During this movement, the seal between the spigot11and annular wall30is maintained by the O-ring seal14. A spent refill is then replaced by a new one following the above procedure.

The cap is provided with a pair of pressure relief valves40. Each is formed by an annular boss41integral with the cap21. A pressure relief valve element42is seated on the top of the annular boss41and is biased in place by a pair of biasing elements43(as shown, for example, inFIG. 5). The biasing force is such that, under normal conditions, the pressure relief valve element42forms an air tight seal on the boss41. However, when the pressure within the bottle20drops below a certain level, the pressure differential across the relief valve element42is sufficient to overcome the force exerted by biasing elements43and to allow air into the bottle20. This reduces the pressure differential thereby restoring the air tight seal without leakage of fluid.

Each pressure relief valve40is surrounded by an annular barrier44which extends axially to a level axially above the level of the top of the annular wall30. Thus, when the valve element33is open, any air entering the relief valve40will not become entrained in the outgoing liquid stream. In practice, this means that the relief valve can be placed closer to the outlet, thereby resulting in a more compact cap. Although two relief valves are shown, a single valve, or more than two valves could be provided if necessary.

The manner in which the cap is assembled is illustrated inFIGS. 5 and 6.

The assembly is a three-part structure consisting of the cap21, a valve plate45and a fixing plate46. The cap has a number of moulded features including the annular flange23, annular wall25and annular bosses41. In addition, the cap21has a plurality of fixing posts47.

The valve plate45is an elastomeric material and is integrally formed with the valve element33, biasing elements34, relief valve element42and biasing elements43. The valve plate has a plurality of locating holes48which correspond to the fixing posts47.

The fixing plate46is made of a rigid plastics material and is integrally formed with the annular barrier44. As with the valve plate45, the fixing plate46is also provided with a plurality of locating holes49which correspond to the fixing posts47.

To assemble the cap, the three components are placed on top of one another as shown inFIG. 6with the fixing posts entering the locating holes to ensure that the components are correctly aligned. Heat or adhesive is then applied to the top of the fixing posts47to secure the fixing posts to the fixing plate46. The elastomeric valve plate45is thereby sandwiched between the cap21and fixing plate46which holds the valve elements33and42in position.

A second example of a cap for a refill unit will now be described with reference toFIGS. 11 to 14.

The structure of the outlet valve element33in the second example is essentially the same as the first example, and will not be described again in relation to the second example.

As can be seen fromFIG. 11, the cap21is integrally molded with a number of features, such as the annular walls25and30and a conical part50of the pressure relief valve which will be described below. A resilient lip53(described in more detail below) for the pressure relief valve is provided integrally molded with the valve plate45. The fixing plate46is also provided with a shield57for the relief valve. This is equivalent to the barrier44inFIG. 2, but only extends around the side of the relief valve facing the outlet valve element33. The barrier44and shield57could be used interchangeably in the two examples.

The cap assembly is assembled in the same manner as in the first example.

The pressure relief valve60is illustrated inFIGS. 13 and 14.

The valve has the conical part50which is an integral part of the cap21as mentioned above. At the top of the conical part50is a cylindrical post61. The resilient lip53is effectively a hollow frustoconical extension of the valve plate52of resilient material which extends along the conical part50from which it diverges slightly and is a tight fit against the post61. At least one air inlet62(also shown inFIG. 11) passes through the wall of the conical part50and is normally covered by the resilient lip53as shown inFIG. 11. When the pressure in the bottle20falls as liquid is emptied the pressure differential across the resilient lip53will eventually become sufficient to displace the lip53to a sufficient degree to allow air A into the bottle20as shown by the arrows inFIG. 8. It should be noted that the degree to which the resilient lip53lifts from the conical element50has been exaggerated inFIG. 8and that, in practice, this will be almost imperceptible.

Instead of sealing against the post, the resilient lip53may seal against the conical part50. In this case, the lip will not diverge from the conical part as shown. Instead, it would actually have an angle of incline less than the angle of the conical part50so as to be naturally biased onto the conical part.