Dispenser, and refill

Abstract

A dispenser capable of dispensing a fluid via a vertically-oriented piezo device comprises a reservoir containing a fluid to be dispensed, an outlet at a base portion of the reservoir, leading to a dispensing port that comprises a piezo element drivable to vibrate and thereby dispense fluid from the dispensing port, a bleed tube communicating at one end with the dispensing port, extending therefrom to a location above the dispensing port, and including a selectively closeable valve, and a source of below-atmospheric pressure to the portion of the reservoir above the fluid. Embodiments of refills suitable for such a dispensing apparatus are also described.

Claims

1. A dispensing apparatus, comprising; a reservoir containing a fluid to be dispensed in an aerosol form; an outlet at a base portion of the reservoir, leading along a conduit to a dispensing port at an end of the conduit; the dispensing port comprising a piezo element which is porous, thereby to permit dispensing from a front side of the element, of fluid contacting the element on a rear side, which is located over the end of the conduit and closes the end of the conduit, and which is drivable to vibrate and thereby dispense fluid from the dispensing port, in use the arrangement being to allow fluid to flow by gravity from the reservoir through the conduit to the piezo element; a bleed tube communicating at one end with the conduit, between the outlet and the closed end, and extending generally vertically from the conduit to a location above the dispensing port, and including a selectively closeable valve; and a source of below-atmospheric pressure to the portion of the reservoir above the fluid.

2. A dispensing apparatus according to claim 1 in which the source of below-atmospheric pressure comprises a piston.

3. A dispensing apparatus according to claim 2 further comprising an openable cover concealing at least part of the apparatus, wherein the piston is operatively connected to the cover so as to impose below-atmospheric pressure to the reservoir on closing the cover.

4. A dispensing apparatus according to claim 1 further comprising an openable cover concealing at least part of the apparatus, wherein the selectively closeable valve is operatively connected to the cover so as to close the valve on closing the cover.

5. A dispensing apparatus according to claim 1 in which the source of below-atmospheric pressure comprises a piston, further comprising an openable cover concealing at least part of the apparatus, wherein the piston and the selectively closeable valve are operatively connected to the cover so as to impose below-atmospheric pressure to the reservoir and close the valve on closing the cover.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which;

(2) FIG. 1 illustrates the principle of operation of the device;

(3) FIG. 2 shows a dispenser being an embodiment of the present invention, with its lid open;

(4) FIG. 3 shows the dispenser of FIG. 2, with the refill cartridge removed;

(5) FIG. 4 shows a vertical section through the dispenser of FIG. 2;

(6) FIG. 5 shows the refill cartridge; and

(7) FIG. 6 shows a semi-transparent view of the refill cartridge.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(8) FIG. 1 illustrates the principle involved in the device. A reservoir 10 contains an amount of fluid 12 which is to be dispensed into the surrounding room. An outlet 14 at the base of the reservoir 10 allows the fluid to flow under gravity out of the reservoir 10 and along a conduit 16 to a dispensing zone 18. This consists of an end to the outlet conduit 16, over which is secured a disc-shaped porous ultrasonic piezo element 20, held in place over the end of the conduit 16 by a flexible seal 22.

(9) When powered by an electrical signal, the piezo element vibrates with a high resonant frequency of about 100-120 kHz. Fluid adsorbed into the rear of the porous disc of the element is then atomised and finely dispersed into the air in front of the element.

(10) We have found, however, that a simple arrangement as described above does not work satisfactorily. Allowing the fluid to flow under gravity to the rear of the piezo element creates too high a pressure behind the element, overloading it and preventing satisfactory resonance. As a result, there is little or no atomisation of the liquid and very little is dispensed.

(11) Two further aspects of the device work together to control the fluid pressure behind the piezo element and ensure that the fluid pressure behind the piezo element is controlled. The first is a source of below-atmospheric pressure that is applied to the volume above the fluid 12 within the reservoir 10. This comprises a syringe 24 in which moves a piston 26, and which is connected to a port 28 at the top of the reservoir 10 via a low pressure conduit 30. As the piston 26 is withdrawn, it will expand any air in the syringe, together with the air in the conduit 30 and any air in the reservoir 10 above the level of the fluid 12. This will create a low pressure zone above the fluid 12 and assist in reducing the pressure behind the piezo element 20.

(12) The second is a bleed tube 32, disposed alongside the reservoir 10. This is generally vertical, and extends from a junction 34 with the outlet conduit 16 just behind the dispensing zone 18, upwards to a point above the dispensing zone 18 and proximate the top of the reservoir 10. A valve 36 at the upper end of the bleed tube 32 is selectively closeable.

(13) The valve 36 is left open during filling or replacement of the reservoir 10. As a result, fluid 12 can flow into the bleed tube 32 via the outlet conduit 16 and the junction 34, expelling air via the valve 36. Before bringing the dispenser into service, the valve 36 is closed (and the piston 26 is withdrawn). The result is that as fluid is dispensed via the piezo element 20, the fluid level in the reservoir 10 will fall. This will seek to draw down the fluid level in the bleed tube, reducing the pressure of the air in the bleed tube above the fluid level. This will assist further in reducing the fluid pressure behind the piezo element 20 and thus control the flow of fluid onto the rear of the piezo element.

(14) Together, these two measures allow sufficient control of the fluid pressure to the rear of the piezo element to allow dispensing of the fluid in the reservoir over a typical service cycle of 30, 60 or 90 days. Whilst both serve to reduce the air pressure above the fluid in the period before and/or during dispensing, and thus either could be used independently, we find that the combination of both has advantages in that neither needs to be particularly aggressive. In other words, the syringe does not need to achieve an exceptionally low pressure; it can thus be primed by the force of (for example) the dispenser door being closed, and does not meet significant leakage problems during a typical service interval. Likewise, the bleed tube does not need to be particularly long, and can thus fit into the approximate size of the reservoir and can be filled by flowback from the reservoir without other assistance.

(15) FIG. 1 shows a dotted outline 38 which encompasses the reservoir 10 and the bleed tube 32. This could form a suitable delineation between the fixed section of the dispenser and a removable refill. Suitable seals could be provided at the top and bottom of the bleed tube, and at the outlet 14 and port 28 of the reservoir, enabling a single removable item to be defined that includes the reservoir and bleed tube. Once the reservoir is exhausted, this item could be removed and replaced with a fresh item (or a recycled and refilled item).

(16) Alternatively, a smaller refill unit 40 could be defined, including only the reservoir 10 and not the bleed tube 32. Thus would have the advantage that the (potentially disposable) refill would cost slightly less, but the larger refill 38 has the advantage that the bleed tube 32 can be placed in front of the reservoir 10, placing the junction 34 proximate the dispensing zone 18 without the bleed tube 32 obstructing removal of the refill.

(17) FIGS. 2 to 6 show a practical implementation of the principle shown in FIG. 1, adopting the larger refill 38. Thus, referring to FIGS. 2, 3 and 4, the dispenser 100 comprises a backplate 102 that can be attached to an upright wall or the like at a suitable elevated location so as to deter tampering (etc). Typically, this is approximately 6 feet (2 meters) from the ground, or higher. The backplate 102 carries a cover 104, shown in an open position, which is hinged to the backplate 102 at its upper edge. Thus, to install or service the dispenser, an operative can lift the cover (after disengaging a suitable latch or lock) to expose the interior of the dispenser.

(18) Within the dispenser 100, there is a lower shelf 106 onto which a refill unit 108 can be placed. FIGS. 2 and 4 show the refill 108 in place, FIG. 3 shows the dispenser 100 with the refill unit 108 removed. Below the shelf 106 are a pattern of outlet conduits 110a, 110b; these lead from a pair of lower bayonet fixings 112, 114 (respectively) to a dispensing zone 118 in the form of a cavity closed at its front face by a piezo disc 120. Each of the bayonet fixings 112, 114 engage with a corresponding outlet 122, 124 on the base of the refill unit as will be described. The outlets 122, 124 are closed with septum-type seals to prevent leakage prior to installation.

(19) At the upper end of the dispenser 100, a clamp bar 126 is provided which can be raised or lowered as necessary. In its lowered position it is spaced above the lower shelf 106 so as to retain the refill 108 in a snug grip. In its raised position, it allows the refill to be disengaged from the lower bayonet fixings 112, 114 and removed from the dispenser 100. On the underside of the clamp bar 126, there are a pair of upper bayonet fixings 128, 130 which engage with corresponding ports 132, 134 on the upper face of the refill 108. The upper bayonet fixing 128 leads to a valve 136 which is normally open but pressed into a closed state when the cover 104 is closed. Upper bayonet fixing 130 leads to the interior of a piston chamber 138; a piston 140 is withdrawn in the piston chamber 138 by levers 142 which extend rearwardly from the piston 140 and then outwardly. Thus, as the cover 104 is pressed shut, it presses on the levers 142 urging them towards the backplate 102, against a spring bias (not shown). This draws the piston 140 back within the piston chamber 138.

(20) Within the refill 108, a tube 144 is fitted to the outlet 124 (at one end) and to the port 132 at the other. This acts as the bleed tube, extending from the dispensing zone 118 upwards to the valve 136. The space within the refill 108 around the tube 144 (but not including the interior of the tube 144) acts as the reservoir and is filled with a fluid to be dispensed.

(21) Thus, as described with reference to FIG. 1, the dispenser is prepared for use by opening the cover 104, which opens the valve 136 and allows the piston to move forward (away from the backplate 102) under the force of the spring bias. The clamp bar 126 is lifted and any refill 108 that is present is removed. A fresh refill 108 is obtained, and is placed over the lower bayonet fixings 112, 114. The clamp bar 126 is then lowered, forcing the bayonet fixings into place and allowing fluid to flow from the reservoir within the refill 108 into the dispensing zone 118 and the bleed tube 144. The cover 104 is then closed, closing the valve 136 and withdrawing the piston 140 thereby creating a low pressure zone above the fluid in the reservoir.

(22) Batteries 146 are provided either side of the refill 108 and provide electrical power to a control unit 148 located above the clamp bar 126. This provides power to the piezo element 120 according to a predetermined program which may be (for example) as described in our earlier patent applications GB 2392438, GB 2392439 and GB 2392440. In outline, these provide for periodic activation of the dispenser as required to provide sufficient fragrance to a room over a period of (typically) between 30 and 90 days. In this embodiment, it will send a suitable drive signal to the piezo element 120 as and when a dispensing event is required.

(23) FIGS. 5 and 6 show the refill 108, FIG. 6 in a part-transparent style so as to illustrate the bleed tube 144 in the interior, linking the outlet 124 with the port 132. Outlet 122 allows fluid to be drained from the interior of the refill 108 around the tube 144, and port 134 allows access to the air space above the fluid, permitting the below-atmospheric pressure to be applied. All four outlets and ports are sealed with septum seals which close in the absence of a bayonet fixing thereby preventing leakage, and open when pierced by a bayonet fixing to allow passage of the relevant fluid or gas. Each is also provided with an external O-ring seal 146 to provide additional sealing.

(24) Thus, the present invention provides a dispenser able to dispense a low-VOX fluid that is not aerosol-based, from an elevated location.

(25) It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention.