This invention relates to an emanator device for delivering an air treatment agent into the surrounding air.
The invention relates in particular to an emanator device for delivering an air treatment agent into the surrounding air, for use in an environment which is alternately wet and dry.
WO 2004/069982 A1 describes an emanator for emanating one or more active component(s), which preferably comprises a surfactant and fragrance. Typically the emanator is for use in a dishwashing machine. The emanator comprises a blister which contains the active component(s) as a concentrated liquid, within a permeable polymeric membrane, through which the active component(s) gradually diffuses. The blister is retained in a cage-like retaining structure. The arrangement, in such a device, is such that the blister is washed over by water in “wet phases” of the dishwashing cycle; and at other times is dispensed into the ambient air. Thus, emanation of the active component(s) occurs without interruption, whether into the ambient air or into the ambient water.
WO 2005/102141 A1 describes an emanator of a similar type, having an aperture or apertures whose size may be varied, in order to provide different rates of release of the active component(s). As in the device of WO 2004/069982 A1, the emanation of the active component(s) is into the ambient environment, whether into water or into air, and 25 thus proceeds without interruption.
It is desirable to fragrance the air in a dishwashing device, to mask the chemical smell sometimes found in a dishwasher, and the odour of dirty dishes and cutlery waiting to be washed. However it is undesirable to add fragrance to the water in the wash cycle, because the crockery and cutlery may have a taint which some users can detect.
WO 2008/141473 A1 describes a malodour-counteracting device for use in an automatic dishwashing machine. The device addresses a problem, that there is increased evaporation of fragrance during the wash cycle, followed by reduced evaporation between washes. The latter time is often when more, rather than less, fragrance is needed, given that dirty dishes and cutlery are loaded into the dishwashing machine, and may be kept there for some hours, before the dishwashing machine is operated. To solve this problem a device is described having a downwardly-open body holding a gradually-releasable fragrance source, and a larger, upwardly open, dish. The body and the dish overlap, but are not sealed to one another; fragranced air can leave the device though a space between the dish and the body. However, during the wet phase of a dishwasher cycle water collects in the dish and thereby rises over the space, preventing fragranced air from leaving the device. However the fragrance source is not itself immersed in water. Fragranced air can not escape from the device until the level of water in the dish falls, by evaporation, to open the space.
The device of WO 2008/141473 A1 achieves the objective of preventing fragrance release during the wet phase, by use of a collected water barrier. However, the device described is aesthetically unappealing, and has functional limitations. The “dish” of the device needs to retain a substantial volume of water in order for the water to close the passage through which fragrance could otherwise escape. To open the passage to its maximum degree appears to require the complete absence of water in the dish. Moreover it is sometimes found that water collected in upwardly-open formations, such as the bases of cups, can contain residues of dirty water, in certain makes of dishwashing machine. This can be expected to occur on occasion, in the upwardly open “dish” of the device of WO 2008/141473 A1. Providing a device which relies upon an upwardly-open dish for alternating closure and non-closure of an emission port or ports is not an optimal technical solution.