Abstract:
In an electrical dispenser ( 10 ) for deodorant or insecticide which contains electric heating means ( 40 ) placed near the first end ( 76 A) of a wick ( 76 ) the second end ( 76 B) of which is dipped into a deodorant or insecticide liquid ( 72 ) contained in a small bottle ( 70 ), the electric heating means ( 40 ) consist of a resistive heating strip ( 40 ) wrapped around the first end ( 76 A) of the wick ( 76 ).

Description:
This application is related to and claims the early filing date of Italian Patent Application No. VE2002A000012, filed Mar. 13, 2002. The entire disclosure of the above application is hereby incorporated by reference. 
   FIELD OF THE INVENTION 
   The present invention relates to an electrical dispenser for deodorant or insecticide of the type comprised of a casing designed to house the upper portion of a small bottle containing a deodorant or insecticide liquid. Inside the casing there is an electrical resistance electrically connected to an electric plug to be inserted in a socket supplied by the standard voltage (for example 220–230V) of an electrical system. 
   BACKGROUND OF THE INVENTION 
   In the art of manufacturing electrical dispensers for deodorants or insecticides, a casing is provided to house the upper portion of a small bottle containing a deodorant or an insecticide. Inside the casing there is an electrical resistance. The electrical resistance is placed near the upper free end of a wick, the other end of which is placed inside a small bottle dipped into a deodorant or insecticide liquid. The latter, due to capillarity, rises through the wick until reaching and impregnating the upper end of the wick. 
   In order to make the dispenser operative, it is necessary to insert the electric plug in a socket: thus, the supplied electrical resistance warms up, the heat generated also heats the upper free end of the wick and the deodorant or insecticide liquid contained within. The deodorant or insecticide liquid is composed of active elements dissolved into a solvent, whereby when the temperature of the wick reaches the evaporation point of the solvent, the latter evaporates releasing in the air the deodorant or the insecticide. 
   There are, however, different embodiments of such a device. 
   SUMMARY OF THE INVENTION 
   A first embodiment consists of a ceramic resistance or, better, a thread resistance inserted in a ceramic element, usually of a parallelepipedic shape, which protects the resistance and, at the same time, operates like a radiator. The ceramic element is placed in contact with the upper free end of the wick. 
   It is easy to understand that the efficiency of such a device is very far from reaching an optimal value, because only a portion of the ceramic element is near the free end of the wick and, then, a great portion of it does not contribute in heating the wick at all. Furthemore, in the case that the ceramic element should be built in a parallelepipedic shape for semplifying the construction, the thermal exchange between the electrical resistance and the free end of the wick is reduced, as well. 
   A second embodiment of the prior art consists of two metallic rings or washers which are overlapped by interposing a tablet or disk made of resistive material. One ring is connected to one of the two electric contacts of the plug and the other ring to the other electric contact of the plug; the free end of the wick is inserted inside the two metallic rings. 
   By supplying the electric plug, the two metallic rings lead the electric current to the resistive tablet or disk which warms up. Then, the heat generated by the tablet or disk passes, by thermal conduction, into the two metallic rings which heat the free end of the wick. 
   Although the heat is generated all around the wick, the amount of the heat trasmitted by the heating elements to the end of the wick still remains low. In fact, only a portion of the two rings is placed near the end of the wick, that is the inner cylindrical surface, whereas, a non negligible surface comprising the outer cylindrical surface, and above all, the two anular surfaces of the two metallic rings faced outwards, does not contribute to heating the end of the wick. 
   Furthermore, all these embodiments have some complications due to the fact that, in addition to having to construct the resistive elements (for example the metallic rings and the resistive tablet), it is necessary to build a casing designed to house all the components, to realize the electric connections in order to connect the metallic rings to the electric plug and to insert all these elements necessary for the correct functioning of the device. For example, in order to avoid that a possible overheating may irreversebly damage the dispenser, it is necessary to insert a protective element against the possible overload of current. Then, a fuse or an electric resistance of low value is inserted and able to accept only a low electrical power, so as to interrupt the current flow in the case its value increases and reaches an unacceptable level. 
   It is clear that, in addition, both the time of construction and assembly becomes longer, with the consequence of relevantly increasing the final cost. 
   The aim of the invention is to build an electrical dispenser for deodorant or insecticide which eliminates the drawbacks cited in reference to the described prior art. 
   In particular the dispenser must have a considerable thermal efficiency between the resistive elements and the end of the wick, thus allowing for the reduction of the dimension of the device and for limiting the intensity of the electric current, with evident advantages. 
   Moreover, the dispenser must be simple, both in construction and assembly phases, in particular it must be composed of only a few elements. Consequently the reliability is increased, whereas the time of construction and the final cost decrease. The aim is reached by an electrical dispenser for deodorant or insecticide initially described, that is comprised of a casing which contains electric heating means placed near a first end of a wick, the second end of which is dipped into a deodorant or insecticide liquid contained in a small bottle, so that said first end is impregnated with a deodorant or insecticide liquid, said electric heating means being electrically connected to an electric plug, so that electrically supplying the plug said first end of said wick warms up and the deodorant or insecticide liquid contained evaporates, characterized in that said electric heating means comprise a resistive heating strip wrapped around said first end of said wick. 
   In so doing, a resistive element is built, i.e. the resistive heating strip, which assures a high efficiency of the thermal exchange with the first end of the wick. The wick, in fact, is completely surrounded by the strip and the strip provides, at the same time, a considerable surface of thermal exchange. 
   In particular the dispenser comprises two cylinders, an outer cylinder and an inner cylinder placed inside and coaxial with respect to said outer cylinder, said outer and inner cylinders define a cylindrical space inside which said resistive heating strip is inserted. 
   The resistive heating strip is thus protected and possible damage is avoided and, moreover, the outer cylinder operates like an insulating barrier for keeping the heat generated contained, thus increasing the thermal efficiency. 
   The resistive heating strip comprises a central portion made of resistive material which surrounds the first end of said wick, and two end portions made of electrically conductive material. In particular said two end portions of conductive materials have narrowed sections so as to make preferential areas of interruption of the electric current in case of overcurrents and, thus, overheating. 
   In this way, possible damage to the dispenser is avoided in the case the current intensity should reach a high level. 
   Preferably, the two end portions of conductive material are electrically connected directly to said electric plug. 
   Consequently, the connections and, thus also the assembly are facilitated, and there is no need to insert other elements or components like fuses and/or connecting leads. 
   The dispenser is thus simple, easy to construct and assemble, reliable and has a low cost. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other advantages will be more evident by the following detailed description of embodiments provided for an illustrative and non limitative purpose with reference to the subsequent enclosed drawings herewithin, wherein: 
       FIG. 1  is a schematic prospective view of a an electrical dispenser for deodorant or insecticide according to the present invention wherein a small bottle of deodorant has also been also represented; 
       FIG. 2  is a schematic exploded view of the dispenser of  FIG. 1 ; 
       FIG. 3  is a schematic prospective view of the support means for a resistive heating strip; 
       FIG. 4  is a top view of the resistive heating strip; 
       FIGS. 5 and 6  are cross sections of  FIG. 4  respectively taken along section lines V—V and VI—VI; 
       FIG. 7  is a top view of a resistive heating strip according to a variant of the invention; 
       FIG. 8  is a schematic prospective view of the support means wherein the resistive heating strip of  FIG. 7  has been inserted. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In  FIG. 1  an electrical dispenser for deodorant or insecticide is entirely represented with reference  10 , and a small bottle  70  is also represented containg a deodorant or insecticide liquid  72 . 
   The electrical dispenser  10  is comprised of a casing  12  wherein there is an upper opening  14 , from which the evaporated deodorant or insecticide goes out, and a lower opening  18  which forms a housing seat  18  for the neck  74  of the small bottle  70 . The dispenser  10  also comprises an electric plug  16  designed to be inserted in a socket supplied to the standard voltage of the electrical system, such as 220–230V. 
   A wick  76  is inserted in the small bottle  70  having a first end  76 A which comes out from the small bottle  70  and a second end  76 B which penetrates inside the small bottle  70  and is in contact with the deodorant or insecticide liquid  72 . 
   The neck  74  of the small bottle  70  is inserted into the housing seat  18  of the dispenser  10 , so that the first end  76 A of the wick  76  is housed inside the dispenser  10  in the manner which will be described in the following. 
   From  FIG. 2 , it can be noted that the casing  12  is comprised of a bottom  20  and a cover  22 . The housing seat  18 , wherein the neck  74  of the small bottle  70  is inserted, is made in the bottom  20 , whereas the upper opening  14 , from which the evaporated deodorant or insecticide comes out, is made on the cover  22 . An opening  24  and an opening  26  have been made respectively in the bottom  20  and in the cover  22  in order to form a seat to house the electric plug  16 . 
   A heating device  30  is housed inside the casing  12  and is able to heat the first end  76 A of the wick  76 . 
   The heating device  30 , as better illustrated in  FIG. 3 , is comprised of an outer cylinder  32  and an inner cylinder  34 . The outer cylinder  32  is cut along a generatrix line to form a longitudinal slot  36  and its inner diameter is greater than the outer diameter of the inner cylinder  34 . By inserting the inner cylinder  34  into the outer clinder  32 , a cylindrical anular space  33  is created, wherein a resitive heating strip  40 , represented in  FIG. 4 , is inserted into it. 
   The resistive heating strip  40  comprises three portions: a central portion  42  and two end portions  44 , 46 . The strip  40  is composed of three overlapped layers: a support layer of insulating material  48 , an intermediate layer  50 , 52  and, at last, an outer covering layer of insulating material  54 . 
   More specifically, as represented respectively in  FIGS. 5 and 6 , in the central portion  42  of the strip  40  there is an intermediate layer of resistive material  50 , whereas in the end portions  44  and  46  of the strip  40  there is an intermediate layer made up of conductive material  52 . 
   For the intermediate layer of resistive material  50  a PTF material (polymer thick film) is used, preferably with PTC characteristics (positive coefficient temperature), so that as the temperature increases, the value of the electric resistance increases, thus limiting the possible overcurrents which may overheat and, thus, damage the dispenser. 
   The intermediate layer made up of conductive material  52  is made, for example, by applying a silver film, since silver is an optimum conductor of electricity. 
   For the support layer of insulating material  48 , polyester is preferably used, as well as for the outer covering layer of insulating material  54 . 
   The width of the resistive heating strip  40  is substantially equal to the height of the outer cylinder  32  and the inner cylinder  34 . Instead, the length of the intermediate portion  42 , containing the resistive layer  50 , is substantially equal to the circumference of the anular space formed between the outer cylinder  32  and the inner cylinder  34  and this portion is inserted in such a way to completely wrap the inner cylinder  34 . Differently, both the end portions  44 , 46  come out from the longitudinal slot  36  of the outer cylinder  32 , as represented in  FIG. 2 , and their length allows for electrically connecting their free ends  44 A and  46 A with the electric plug  16 . 
   In both end portions  44  and  46 , the conductive material  52  is uniformly applied over the total surface of the support layer  42 , except for the two areas wherein the material is applied in a manner to form two narrowings or reduced sections for the flow of electric current, respectively indicated by references  56  and  58 . The narrowings  56  and  58  form two preferential areas of interruption of the electric current in the case of overcurrents, and thus of overheating. 
   In  FIGS. 7 and 8  a variant of the invention is represented, wherein the elements already described have been indicated with the same references plus  100 . 
   In this case, the resistive heating strip  140  comprises a central portion  142 , the width of which is still substantially equal to the height of the outer cylinder  132  and the inner cylinder  134 , whereas the two end portions  144 , 146  have a width lesser than half the height of the outer and inner cylinders  132 , 134 . The two end portions  144 , 146  are oppositely arranged so as to come out tangentially with respect to the cylinders  132 , 134 , without superimposing each other (see  FIG. 8 ), thus avoiding any fold which might jeopardize the correct functioning of the resistive heating strip  140 . 
   The assembly of the electrical dispenser  10  is very easy. 
   In fact, after having inserted the inner cylinder  34  into the outer cylinder  32  and after having inserted the resistive heating strip  40  in the anular space, designed in the way described above, it is sufficient to connect the free ends  44 A, 46 A of the end portions  44 , 46  to the electric plug  16  and, at last, enclose everything by coupling the bottom  20  with the cover  22 . 
   To operate the device, it is also necessary to insert the neck  74  of the small bottle  70  into the housing seat  18  of the dispenser  10 , so that the first end  76 A of the wick  76  is housed inside the cylinders  32 , 34  and to insert the electric plug  16  into a standard electric socket. 
   In such a manner, due to the “Joule effect”,the central portion  42  of the resisive heating strip  40  gets warm and, consequently, by thermal conduction, also the inner cylinder  34  and the outer cylinder  32 , and then the first end  76 A of the wick  76  inserted into, warms up. The temperature arrived at is sufficient for evaporating the solvent contained in the deodorant or insecticide liquid and, then, to permit for the release of the deodorant or insecticide substance dissolved therein. 
   It is evident that the thermal exchange between the resistive heating strip  40  and the wick  76 A is significant, thus permitting the dispenser to run efficientely. 
   In order to facilitate the heat transmission towards the first end  76 A of the wick  76 , the central portion  42  of the resistive heating strip  40  is placed in strict contact with the outer surface of the inner cylinder  34 ; consequently, an air gap which functions as insulation is formed between the resistive heating strip  40  and the inner surface of the outer cylinder  32 . 
   In addition, it is possible to make the outer cylinder  32  and the inner cylinder  34  of different materials: preferably the outer cylinder  32  should be made up of thermically insulating material so as to minimize, or even make negligible, the loss, namely of heat transmission outwards, whereas the inner cylinder  34  should be made up of a thermally conductive material. 
   From the above-said, the dispenser  10  is composed of only a few components that are easily constructed and also the assembly is simple and rapid. Therefore, the cost is reduced and the reliability is very high. 
   Finally, it is evident that changes or variations conceptually or functionally equivalent fall inside the scope of the present invention. 
   For example, the central portion made up of resitive material  42  might be wound like a helix inside the anular cylindrical space  33  formed between the outer cylinder  32  and the inner cylinder  34 , so as to form various rotations. 
   Or, aramidic fibers might be used for the support layer of the insulating material  48  and for the outer covering layer of insulating material  54  which are very strong so as to allow a remarkable reduction of the thickness of said strip with evident advantages.