AIR FRESHENER DEVICE

Abstract: A fragrance emanating device for freshening atmospheric air, which device comprises: (i) a closed container for accommodating a liquid fragrance composition, (ii) an emanator having a surface open to the atmosphere for the evaporation of the liquid fragrance composition, and (iii) conduit means linking the container and the said emanator surface, the arrangement being such that, in use, thermal expansion of the air and/or liquid in the container resulting from an increase in temperature causes the fragrance composition to travel along the conduit means from the container to the emanating surface of the emanator and thermal contraction of the air and/or liquid in the container resulting from a decrease in temperature causes air from the atmosphere to enter the container via the conduit means. The device of the present invention enables a fresh supply of fragrance composition to be fed to the emanating surface of the device each day, thereby preventing gradual diminution in the rate of emanation of the fragrance composition with time.

Description: AIR FRESHENER DEVICE This invention relates to air freshening devices of the type suitable for use in domestic environments. It is known to provide air freshening devices which slowly release a fragrance into the atmosphere in order to avoid or mask unpleasant odours. Such air freshening devices may comprise a gel-like matrix containing one or more fragrance components . The matrix includes an emanating surface from which the fragrance evaporates on contact with the air. However, such conventional air freshening devices suffer from the disadvantage that the concentration of the fragrance component or components remaining within the matrix decreases with time and a concentration gradient thus forms across the matrix. Thus, as time passes, the emanating surface contains less fragrance and the rate of fragrance emanation decreases. The user of the air freshening device then perceives that the air freshening device is less efficient as time progresses . An alternative type of air freshening device comprises a liquid in a container provided with a wick into which liquid can be drawn by capillary action, and from which the volatile liquid can evaporate from the exposed end of the wick. As the level of liquid in the container falls, the liquid must travel a greater distance up the wick before it can evaporate. As a result it is difficult to obtain a uniform release of fragrance over time. We have now developed a fragrance emanating system which overcomes the above disadvantage. Accordingly, the present invention provides a fragrance emanating device for freshening atmospheric air, which device comprises :- (i) a closed container for accommodating a liquid fragrance composition, (ii) an emanator having a surface open to the atmosphere for the evaporation of the liquid fragrance composition, and (iii) conduit means linking the container and the said emanator surface, the arrangement being such that in use, thermal expansion of the air and/or liquid in the container resulting from an increase in temperature causes the fragrance composition to travel along the conduit means from the container to the emanating surface of the emanator and thermal contraction of the air and/or liquid in the container resulting from a decrease in temperature causes air from the atmosphere to enter the container via the conduit means . By means of the present invention a fresh supply of the fragrance composition is fed to the emanating surface with each temperature increase and temperature decrease cycle. Thus there is no gradual diminution in the rate of emanation with time. In a particularly preferred embodiment, the container includes a base at one end to enable the device to be supported on a level surface and, at its other end, it includes an emanator having a dished emanator surface. The conduit means connecting the container and the emanator may be in the form of a dip tube, generally vertically disposed within the interior of the container, and extending between the emanating surface and the base of the container. By suitable selection of the volume of the container, the volume of the conduit means and the diameter thereof, it can be ensured that the thermal expansion and contraction occurring with daily changes in the temperature of the air cause fragrance composition to be expelled from the container to the emanating surface and air to be drawn into the container from the atmosphere to replace the expelled fragrance. If appropriate, the container my be suitably thermally insulated in order to achieve the desired daily range of temperature variation. In one embodiment of the present invention, the container is only partially filled with the fragrance composition so that it also includes atmospheric air. In this case, it is primarily the expansion of the air above the surface of the fragrance composition with temperature change which results in the desired expulsion of the fragrance composition from the container. Alternatively, the container may initially be completely filled with fragrance composition, in which case the thermal expansion of the fragrance composition itself provides the driving force for expelling the fragrance composition from the container. Alternatively, the device may be primed by removal of an initial charge of liquid, for example, applying pressure to a flexible container which is full of the fragrance composition. As time passes, air will be drawn into the container and the expansion and contraction of the air will then contribute to the expulsion of fragrance composition in subsequent temperature cycles . In another embodiment, the driving force is derived from the liquid only. In this case the device includes a reservoir to top up the container with liquid as fragrance composition is removed and a means is provided for removing the air which enters the container from the atmosphere during cooling. The control of liquid flow and air removal may include various valve arrangements . In one form of this embodiment, the container may include another liquid, in addition to the liquid fragrance composition. This other liquid may be a liquid miscible with the liquid fragrance composition (such as ethanol) or a liquid which is immiscible with the liquid fragrance composition (such as water or a perfluoroether) and similarly provides the driving force for expelling the fragrance from the container due to its thermal expansion and contraction. The container may be formed of, for example, plastics material, glass, ceramic, pottery or metal, the prime requirement being to contain the liquid fragrance composition and the air in a manner such that expansion can only occur up the dip tube. The emanator may be formed from a porous material which may be treated so as to make it hydrophobic or lipophobic, as appropriate. Suitable porous materials include ceramics or earthenware, plastics material, paper, cellulose wadding and finely divided mineral particles, such as silica, alumina or carbon. The emanator may be in the form of a flat plate or a film, planar or curviform, and may be wholly formed from the porous material or may be a composite of porous and non- porous material. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which :- Figure 1 is a schematic cross-sectional side view of a device in accordance with the invention, prior to use; and Figure 2 is a cross-sectional view of the device of Figure 1 during the elevated temperature portion of a daily cycle. Referring to Figure 1, there is shown a closed vessel 1 formed of, for example, a plastics material having a planar base portion 2. Mounted on the upper portion of the vessel 1 is an emanator 3 having an upper dished emanator surface 4. The emanator 3 is formed from a porous ceramic material. A conduit in the form of a vertical dip tube 5 is provided having its upper end in communication with the emanating surface 4 and its lower end terminating slightly above the base portion 2 of the vessel . The vessel is partly filled with a liquid fragrance composition 6 so that the upper portion 7 of the vessel contains air. The amount of liquid fragrance in the vessel is such that the lower end of the dip tube 5 is submerged. At constant pressure, which is essentially what occurs in a device of less than 150 mm in height, the volume coefficient of expansion of air is 0.35% per degree C at 10°C. Thus suitable ranges for the dimensions of the component parts of the device can be calculated depending upon variables such as the operational lifetime of the device, the amount of liquid expelled, whether the fragrance is diluted in some way, etc. The overall volume of the closed vessel may be from 2 millilitres to 2 litres, with a preferred range of from 10 ml to 200 ml, with the liquid volume calculated according to the nature of the fragrance composition, the required working life, the expected temperature range etc. The diameter of the dip tube would typically lie between 1.0 and 5.0 mm. As shown in Figure 2, a slight expansion of the air in the upper portion 7 of the vessel has forced the liquid fragrance composition to rise slightly up the dip tube 5. As the temperature rises during the course of the day, the expansion of the air in the vessel increases and the relative volumes of the vessel 1 and the dip tube 5 are such as to cause liquid fragrance composition 6 to rise up the dip tube 5 and form a pool 8 on the surface 4 of the emanator 3. The liquid pool 8 becomes absorbed into the emanator. The fragrance evaporates from this pool and freshens the air. As the temperature falls during the night, the air in the vessel 1 contracts and the liquid fragrance composition in dip tube 5 is drawn back into the vessel 1. Continued contraction of the air then draws additional air from the atmosphere into the vessel via dip tube 5 to replace the expelled liquid fragrance composition because of the relationship between the volume of the vessel 1 and the volume of the dip tube 5. On each successive temperature cycle, fresh fragrance is delivered to the emanator, from where it evaporates into the air. With successive introductions of atmospheric air into the vessel, for a given range of temperature cycling, the absolute volume expansion increases with successive temperature cycles. As a result, an increased amount of liquid fragrance composition is fed to the emanator every 24 hours, with a corresponding increase in fragrance strength in contrast to conventional slow release air freshening devices where the fragrance strength gradually decreases with time. The device of the present invention is particularly suitable for use in rooms where there is a diurnal temperature variation so that the emanator is charged with fresh fragrance composition each day .

Claims: CLAIMS : 1. A fragrance emanating device for freshening at opsheric air, which device comprises :- (i) a closed container for accommodating a liquid fragrance composition, (ii) an emanator having a surface open to the atmosphere for the evaporation of the liquid fragrance composition, and (iii) conduit means linking the container and the said emanator surface, the arrangement being such that, in use, thermal expansion of the air and/or liquid in the container resulting from an increase in temperature causes the fragrance composition to travel along the conduit means from the container to the emanating surface of the emanator and thermal contraction of the air and/or liquid in the container resulting from a decrease in temperature causes air from the atmosphere to enter the container via the conduit means. 2. a device as claimed in claim 1 wherein the emanator has dished surface. 3. A device as claimed in claim 1 or claim 2 wherein the conduit means comprises a dip tube vertically disposed within the container which extends between the emanator surface and the base of the container. 4. A device as claimed in any one of the preceding claims wherein the container is thermally insulated. 5. A device as claimed in any one of the preceding claims wherein the container initially includes atmospheric air therein. 6. A device as claimed in any one of claims 1 to 4 wherein the container initially is completely filled with liquid. 7. A device as claimed in claim 6 which includes a reservoir for topping up the container with a liquid as the fragrance composition is expelled therefrom. 8. A device as claimed in any one of the preceding claims wherein the emanator is formed from a porous material . 9. A device as claimed in claim 8 wherein the porous material comprises a ceramic or earthenware material, a plastics material, paper, cellulose wadding or finely divided mineral particles. 10. A device as claimed in claim 8 wherein the dip tube has a diameter of from 1.0 to 5.0 mm. 11. A device as claimed in any one of the preceding claims wherein the container has a volume of from 10 to 200 ml.

Inventors: CHANNER ROBERT VERN, CHANNER, ROBERT, VERN
Applicants: CHANNER ROBERT VERN, RECKITT BENCKISER UK LTD, CHANNER, ROBERT, VERN, RECKITT BENCKISER (UK) LIMITED
Application year: 2000
Main classification: A61L9
IPC codes: A61L9