Abstract:
A unit ( 1 ) for the transfer and distribution of a liquid ( 27 ) using capillary action has an elongated shaft ( 2 ) and a screen ( 3 ) The shaft ( 2 ) includes a first capillary medium ( 4 ) suitable for drawing the liquid ( 27 ) from a reservoir ( 26 ) into the shaft ( 2 ) when a bottom portion ( 20 ) of the shaft ( 2 ) is disposed in the liquid. The screen ( 3 ) is connected to the shaft ( 2 ) and includes a second capillary medium ( 5 ) suitable for receiving the liquid ( 27 ) drawn by the first capillary medium ( 4 ) and distributing it over at least a major part of the screen ( 3 ) where it evaporates.

Description:
[0001]    The present invention relates to a unit for the transfer and distribution of a liquid and a method of manufacturing the same according to claims  1  respectively  12 . The invention further relates to a refill for a dispenser for volatile liquids according to claim  16 .  
         BACKGROUND OF THE INVENTION  
         [0002]    In order to transfer liquids it is known to use capillary action which is dependent on the cohesive forces within the liquid and the adhesive forces of the liquid to a capillary medium comprising small channels, e.g. pores or spaces between fibers. Such a capillary medium, e.g. a wick, being introduced through an opening into a reservoir, can therefore be used to draw a liquid out of said reservoir passively by means of capillary action only, i.e. without additional sucking. The transferred liquid may be used to distribute chemical substances to the ambient air in order to generate or mask an odour, to evoke a medical or organoleptic effect or to affect insects.  
           [0003]    The U.S. Pat. No. 5,114,625 discloses a fragrance dispenser with a liquid reservoir and a wick with a liquid receiving end disposed in the reservoir for drawing liquid therefrom into the wick. A portion of the wick length is exposed to an air flow provided by a fan.  
           [0004]    However, the distribution of volatile chemical substances contained in the liquid in the air flow is not sufficiently homogenous when the air flow is brushing over the wick. Further, in most cases dispensing a substance cannot be done without generation of an external air flow in order to evaporate a given amount of liquid per unit time.  
           [0005]    The wicks used in prior art dispensing devices are difficult to exchange as they have to be mounted in such a way that the wick is arranged in a defined position relative to the reservoir. This is rendered difficult as wicks are generally soft. Further, the reservoir including the wick has to be tight to prevent spilling of the liquid and uncontrolled evaporation. The same problem arises with a refill for such a device. A refill already including a wick has to be tightly sealed before use, while refill and wick separated from each other have to be such that the wick is easy and clean to insert and the refill is tight before and during use.  
           [0006]    It is therefore an object of the invention to provide a unit for the transfer and distribution of a volatile liquid that has a good efficiency in evaporating liquid, is easy and cheap to manufacture and is easily and hygienically insertable into a reservoir, especially the reservoir of a refill.  
           [0007]    It is another object of the invention to provide a method of manufacturing such an improved transfer unit.  
           [0008]    It is a further object of the invention to provide a refill suited for the use with such a transfer unit.  
         SUMMARY OF THE INVENTION  
         [0009]    The above and other objects of the invention are achieved by a transfer unit as specified in claim  1 , a method of manufacturing the same as specified in claim  12 , a refill as specified in claim  16  and a dispenser with such a transfer unit and such a refill.  
           [0010]    According to the invention a shaft comprising a first capillary medium to draw a liquid into the shaft due to capillary action, e.g. a wick, scrib rod or a porous rod, is provided with an integrated screen to serve as an enlarged liquid receiving area from which the liquid is easily evaporated to the ambient air. To provide an enlarged area, the screen is preferably at least two to three times as wide as the shaft. By capillary action the liquid is drawn from the shaft to the screen and distributed over it, using a second capillary medium connected to the first capillary medium. As first capillary medium in general any material capable of absorbing and transferring a liquid due to capillary action is suited, e.g. material containing natural or synthetic fibers, woven or non-woven fabrics, porous media, capillary tubes, or a rod with external grooves, e.g. as described in U.S. Pat. No. 4,913,350. As second capillary medium a material with open pores from which liquid evaporates is suited, e.g. material containing natural or synthetic fibers, woven or non-woven fabrics, porous media. In a preferred embodiment first and second capillary medium are a single piece, for example shaft and screen are made of a sheet of card board or non-woven welded or laminated material, which is cheap and therefore suited for the production of a mass article. Shaft and screen are preferably rigid to maintain the shape of the transfer unit and its position with respect to the reservoir when introduced into the dispenser.  
           [0011]    In a preferred embodiment of the invention the screen is permeable to air flow through the screen in a direction approximately normal to the plane of the screen. This can be achieved by a screen having one or more openings. In one preferred embodiment there are a plurality of “small” openings, each with an area less than 5% of the total screen area, distributed preferably uniformly over the screen and result in openings in the screen totalling no more than 95%. By the screen material itself being capillary at least between the openings the liquid is distributed over the screen and around the openings where it evaporates. Additionally or alternatively, the openings or the whole screen area can be covered with another air permeable capillary medium, such as a gauze sheet or tissue paper, which additionally respectively solely receives and distributes the liquid. In this case there is not need for the openings being “small”, i.e. one or more “bigger” openings each with an area of equal to or greater than 5% of the total screen area can be used to transmit the air. To enhance evaporation, an externally generated air flow is advantageous but not essential.  
           [0012]    The refill according to the invention comprises a reservoir containing the liquid, an outlet opening and a shaft receiving passage starting at the outlet opening and projecting inward. The shaft receiving passage is suitable for receiving the shaft of the transfer unit as described above. Preferably the receiving passage is dimensioned to tightly embrace the shaft, as this stabilizes the transfer unit and a capillary effect can be achieved between the shaft and the walls of the receiving passage enhancing the capillary action of the shaft itself. Another embodiment of the shaft may be envisaged where lower-capillary action is required. This can be achieved through tapering of the shaft for the lower portion of ist length, such that it is not in intimate contact wiht the lower portion of the receiving passage. The refill and the shaft receiving passage may be moulded in one piece which can be produced at low cost. In a preferred embodiment the shaft receiving passage comprises a seal, e.g. a metal foil, plastic moulding, or any inpervious material that can be easily punctured isolating the liquid in the reservoir from the outside. Preferably, the seal is located at the bottom end of the passage and may be punctured by the shaft when fully introduced into the refill. A commercial embodiment of this could have the shaft partially introduced into the shaft receiving passage and the action of inserting the refill into the main unit causes the shaft to break the seal. To facilitate breaking the seal the shaft preferably comprises a cutting member at its bottom portion, e.g. a tip or a thorn or a knife-like element. Seal location at the bottom end of the passage is advantageous as the narrow passage protects the seal against accidental damage. The refill can thus be sold ready for use without an extra cover of the outlet opening, such as a lid, thus saving material, waste and manufacturing costs. Introduction of the shaft can be accomplished without spilling.  
           [0013]    The transfer unit is preferably sold in a blister package containing one or more transfer units or a refill and an isolated unit insertable into the refill.  
           [0014]    A coating of the lateral shaft faces respectively a layer around these faces impermeable to liquid is advantageous as it prevents softening of the shaft and stabilizes the shaft. Further, it enables the control of the dispensed amount as liquid flow can be stopped by tilting or turning the reservoir, thus preventing contact of the bottom portion with the liquid. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 shows a transfer unit with a shaft and a screen with a plurality of “small” openings;  
         [0016]    [0016]FIG. 2 shows a transfer unit with a shaft and a screen both having a plurality of “small” openings;  
         [0017]    [0017]FIG. 3 shows a transfer unit with a shaft and a screen having one “big” opening;  
         [0018]    [0018]FIG. 3A shows a generic shaft which may have screens as depicted in FIG. 1- 3 , but has tapered lower portion;  
         [0019]    [0019]FIG. 4 a - c  shows different views of a shaft receiving passage;  
         [0020]    [0020]FIGS. 5 a,b  shows the insertion of a transfer unit into the shaft receiving passage of FIG. 4 a - c;    
         [0021]    [0021]FIGS. 5 c,d -shows a view of a shaft receiving passage with the tapered shaft as shown on FIG. 3A 
         [0022]    [0022]FIGS. 6 a,b  shows a refill with a transfer unit;  
         [0023]    [0023]FIG. 7 shows one method of manufacturing the transfer units as shown in FIG. 1;  
         [0024]    [0024]FIG. 8 a  shows an example of a perforated sheet as a sheet material for transfer units as shown in FIG. 2;  
         [0025]    [0025]FIG. 8 b  shows a method of manufacturing transfer units as shown in FIG. 2 using the sheet of FIG. 8 a;    
         [0026]    [0026]FIGS. 9 a,b  shows a method of manufacturing transfer units as shown in FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    [0027]FIG. 1 shows a transfer unit  1  with an elongated shaft  2  and a screen  3 . The shaft  2  consists of a first capillary medium  4 , here absorbent card board  4 ′, preferably 1 to 4 mm thick. The shaft  2  may have, but is not restricted to a rectangular shape with a width W 1  of preferably 5 to 10 mm. The length of the shaft  2  is greater than the width W 1  and is chosen such that at least the bottom portion  20  of the shaft  2  is in contact with the liquid, e.g. a perfume, when introduced into a liquid reservoir. The bottom portion  20  has a tip  20 ′ to facilitate breaking a seal, as shown in FIGS. 5 a,b.  The screen  3  consists of a second capillary medium  5  with a plurality of “small” openings  6  punched out to allow air to pass through, each opening  6  covering less than 5% of the total screen area. The width W 2  of the circular screen  3  is about three times the width W 1  of the shaft  2 . Screen  3  and shaft  2  are made of the same material, a card sheet, i. e. in this embodiment for the second capillary medium  5  the same material as for the first capillary medium  4  is used. Alternatively, different capillary materials could be connected to enable liquid transfer to the screen  3 .  
         [0028]    [0028]FIG. 2 shows another example for a transfer unit  7  with a shaft  8  and a screen  9  both having a plurality of “small” openings  12 ,  12 ′. Its shape is generally the same as of the unit of FIG. 1. As a capillary material for the capillary media  11  and  10  of screen  9  respectively shaft  8  an absorbent card  10 ′ with perforations that constitute the openings  12 ,  12 ′ is used, e.g. as shown in FIG. 8 a.    
         [0029]    [0029]FIG. 3 shows a third example for a transfer unit  13  with a shaft  14  and a screen  15 . The screen  15  comprises an annular frame  18  with a central opening  17 , that covers approximately 80% of the screen area (“big” opening). The opening  17  is covered with a sheet of capillary air permeable material, here a gauze sheet  19 ′. The gauze sheet  19 ′ receives as a second capillary medium  19  liquid drawn into the shaft  14  and to the screen  15  by the first capillary medium  16 . The frame  18  is made of the same material as the shaft  14 , here card board  16 , i.e. the frame contributes to the distribution and transfer of the liquid to the gauze sheet  19 ′ using capillary action. FIG. 3A shows a transfer unit  1 ′ with an elongated shaft  2 ′ and a screen  3 . The shaft  2 ′ consists of a first capillary medium  4 ′ preferably 1 to 4 mm thick. The shaft  2 ′ has a rectangular shape at its upper most portion directly below the screen, and a triangular taper for the remainder of its length with the taper comprising of 5% to 95% of the total length of the shaft. The length of shaft  2 ′ is greater than the maximum width and is chosen such that at least the bottom portion of the shaft is in contact with the liquid.  
         [0030]    In another embodiment (not shown) the frame  18  is made of a non capillary material, such as plastic or metal, serving to stabilise the second capillary medium  19  which is connected to the shaft for liquid transfer. In yet another embodiment (not shown) the shaft itself comprises a frame made of non capillary material stabilising a first capillary medium, e.g. a gauze sheet or a tissue paper, being connected to the second capillary medium, preferably the second capillary medium being an integral part of the first-Capillary medium.  
         [0031]    [0031]FIG. 4 a - c  shows different views of a shaft receiving passage  21  dimensioned to receive the shaft of a transfer unit. A transfer unit  1  being introduced into the receiving passage  21  is shown in FIGS. 5 a,b.  The receiving passage  21  may be an integral part of a refill for an air freshener or the like, as shown in FIGS. 6 a, b,  or may be suited for insertion into the outlet opening of a liquid reservoir.  
         [0032]    The receiving passage  21  comprises an elongated sleeve  23  having a rectangular cross section dimensioned to tightly embrace the shaft  4  of transfer unit  1 . The receiving passage  21  further comprises a fitting  22  adjacent to the sleeve  23  having circular cross section. The fitting is dimensioned to tightly fit into a circular outlet opening of a liquid reservoir  26 . The fitting  22  comprises an annular flange  35  to seal the outlet opening when the passage  21  is inserted. In case the receiving passage is an integral part of the liquid reservoir  26  the fitting  22  is not essential as the passage  21  and the reservoir  26  can be moulded in one piece. The passage  21  guides the transfer unit  1  into a defined position with respect to the dispensing device, e.g. to a fan generating an air flow. In this position transfer unit  1  is mechanically stabilised by passage  21 .  
         [0033]    [0033]FIG. 5 c - d  are similar to FIG. 4 b - c  except that they depict a shaft receiving passage  23 ′ containing a tapered shaft  2 ′, as shown in FIG. 3 a.  The receiving passage has a cross section dimensioned as not to tightly embrace the shaft  2 ′ hence leaving a gap between the shaft and receiving passage of at least 1 mm on both front and back sides. In this embodiment there will be a tight; fitting portion at the top  36 ′ of the receiving passage  23 ′ to hold the transfer unit  9 ′ in place.  
         [0034]    The bottom opening of the passage  21  is closed with a foil seal  24  that can be punctured by the shaft  4  as shown in FIGS. 5 b  and  6   b.  The seal  24  isolates the liquid  27  contained in the reservoir  26  of the refill  25  from the outside, no extra lid is needed. When the transfer unit  1  is inserted, the tip  20 ′ of its bottom portion  20  breaks the seal  24 , the liquid  27  has access to the shaft  4  immediately, is drawn up to the screen  3  and evaporated.  
         [0035]    [0035]FIGS. 7, 8 b  and  9   a - c  show methods of manufacturing the transfer units as shown in FIG. 1 to  3 . The transfer unit of FIG. 1 is manufactured by punching a shape  29  with a circular main body  29 ′, forming the screen afterwards, and an elongated part  29 ″, forming the shaft, from a sheet  28  of capillary material. This shape  29  can be punched in one go with a plurality of holes  29 ′″ arranged within the main body shape  29 ′ or before or after punching the holes  29 ′″.  
         [0036]    A pre-perforated sheet or mat  30  of capillary material with a plurality of holes  31  as shown in FIG. 8 a  serves as basis for manufacturing transfer units shown in FIG. 2. A shape  29  as, described above is punched from the sheet  30 . The cut out shape is ready to use as a transfer unit.  
         [0037]    The steps of an alternative manufacturing method are depicted in FIG. 9 a - c,  where “big” holes  33  are punched from a continual mat or sheet  32  (FIG. 9 a ). Then a strip of continual air permeable capillary material  34  such as gauze is glued over the holes  33  (FIG. 9 b ). A shape  29  as described above is punched from the sheet  32 , where the shape  29  is positioned such that each hole  33  is located in the center of the circular main body  29 ′.  
         [0038]    The inventive transfer units  1 ,  7 ,  13  as shown above can thus be manufactured at very low cost as the materials used, e.g. gauze, cardboard, fleece, are cheap and the methods of manufacturing described in FIG. 7 to  9  involve three steps at most.