Apparatus to keep flying insects, particularly mosquitoes, away from people

Abstract: In order to keep flying insects, especially mosquitoes, away from people, the apparatus comprises a box (A, A″) enclosing a heat source (10, 50) provided with at least one vertically orientated flat wall (13′, 53′) and a container (C, C′) holding an evaporable liquid. A wick (14, 54) coated with an impermeable material or sheath (19, 59), with a rectangular cross section, penetrates inside the container. A portion (14″, 54″) of wick, devoid of coating, extends upwards from the container (C, C′), its largest side (14‴, 54‴) being disposed parallel to the heat source (10, 50). Inside the container, the entire length (L) of the wick is sur­ rounded by this sheath, except for the extreme lower free portion from where the liquid is absorbed and rises exclusively by capil­ larity to the far upper area, where the wick is heated and the liquid evaporates.

Description: The present invention concerns an apparatus to keep flying insects, particularly mosquitoes, away from people, comprising a box which encloses a container containing an evaporable liquid chemical product which is drawn up by a wick after heating an upper portion of said wick by means of a heating device, the box encloses said heat source provided with at least one flat wall set at right angles to the base of the container situated below, which contains the evaporable liquid and into which penetrates the wick, the extreme upper portion of said wick is disposed near the flat wall of said heat source. GB-A-2,194,442 discloses the aforementioned features. There are numerous known apparatus marketed everywhere which are designed to protect people from mosquitoes and from other small troublesome insects. These known apparatus use emanators provided with tablets which, when placed near or adjacent to a heat source, give off the evaporable substances with which they are impregnated, in the form of smoke. Also known are apparatus for evaporation by heating a wick, in which a liquid chemical product contained in a bottle is drawn up by capillarity into the wick, which is immersed in this product. A drawback of these known apparatus is that they generally have a limited capacity for drawing up and evaporating liquid through the wick; moreover, the heat-vaporizing part of the apparatus cannot be replaced economically when necessary. Furthermore, in these apparatus, the bottle containing the liquid chemical product is inserted from below, an operation which proves rather difficult and can easily result in damage to the wick. The aim of the present invention is to provide an apparatus which offers long-lasting evaporation of insecticide, air freshener or deodorant, which is capable of evaporating the amount of liquid chemical substance in an efficient, uniform manner and which allows rapid, safe replacement of the container of the liquid substance. It is characterized in that the wick is coated with an impermeable material which covers almost its entire length, leaving free of coating the extreme lower portion of said wick and the extreme upper portion of said wick which protrudes from the container. According to a preferred embodiment, the wick has a rectangular cross section, in particular wide and flat, offering a flat surface to the heat source. The coating-free surface of the extreme lower portion of the wick is very small compared with that of the wick coating itself, whereas the coating-free surface of the extreme upper portion of the wick is greater and has an enlongated shape. Preferably, during operation of the apparatus, the chemical substance in the container is drawn into the wick by capillarity, starting from an area of the wick near the base of the container, where the temperature is lower, until it reaches an area adjacent to a heat source at a distance from said base and outside said container, where the temperature is higher. Singularly, provision is made for the wick to consist of an absorbent material, in particular cardboard, or in any case a cellulose and/or cotton linter based material, containing about 20% mineral dust, preferably basalt. An advantageous characteristic according to the invention lies in the fact that the coating of the upper area of the wick is surrounded by a closing device for the container, in the form of an externally cylindrical stopper, which can be tightly inserted into the neck of the tank and that the wick, the coating and stopper form an inseparable unit. In particular, in the extreme lower part, the wick coating extends downwards forming two teeth, as a protection for the portion of wick protruding from the coating. These two teeth face each other and may be connected at their respective ends, in order to form a lower stop for the wick. This apparatus is therefore particularly suitable for places in which it is necessary to adopt adequate protection against domestic insects for long periods, and consequently has a longer operating period than that of the devices usually available on the market and which furthermore can be reused many times, requiring only the user to insert or remove the electrical connecting plug fitted at the end of the conductor of the apparatus or on the apparatus itself, or operate the relative switch. The invention will now be described on the basis of schematic drawings and exemplary embodiments, in which: Fig. 1 shows a vertical longitudinal section of an apparatus directly provided with an electrical power plug; Fig. 2 shows a plan view from above of the apparatus with the door, opposite the plug, open; Fig. 3 is a front view of the apparatus, seen in the direction of the arrow F in Fig. 1; Fig. 4 shows a view of the container complete with stopper, sheath and wick; Fig. 5 is a partially cut-away view of a wick unit; Fig. 6 is a section along the vertical plane VI-VI of Fig. 5; Fig. 7 is a section along the horizontal plane VII-VII of Fig. 5; Fig. 8 is a view from above of the wick unit in Fig. 5; Fig. 9 is a longitudinal section of another example of the apparatus; Fig. 10 is a plan view from above of Fig. 9; Fig. 11 shows the apparatus seen in the direction of the arrow F′; Fig. 12 represents a method of engaging the container housed in the box of the apparatus, seen from above. With reference to figures 1 to 8, the apparatus comprises a box A made of artificial material. It consists essentially of two assemblies, the first of which, the lower assembly A′, has a base 1, two sides 2, 2′ and a front wall 3, set at right angles to each other. The wall 4, on the side facing away from the front wall 3, is shaped to form a semi-circle and advantageously serves as a door. The wall 4, when it serves as a door, is obtained in a single piece with one of the two sides 2′ and is articulated on a vertical edge 2″ of this side. The second assembly or cover 5 of the box is shaped on the outside like a parallelepiped, but with the front wall 3 prolonged downwards to partially house a rotating plug 6. Said assemblies A′ and 5 make up a single unit owing to the existence of means 7, 7′ which can be spring engaged with one another. The plug 6 rotably mounted on the front wall 3 of the box can turn through an angle of 90°. Inside box A the wires 8 of the plug 6 are connected to a switch 9, preferably luminous, which protrudes a little from the top surface of the cover 5, to a possible timer and to a heating element 10. The latter element 10 is preferably in the form of a casehardened wire-wound resistance, in turn inserted into an axial through-hole 12 in a block 13, made of ceramic or appropriate artificial electrically insulating material, shaped like a parallelepiped and having a rectangular cross-section. Instead of the plug rotating 90°, the apparatus can be provided with a lead of a suitable length coming out of the box, so that the apparatus can be placed at a distance from the power point. The wick 14, more fully described later and of which only the extreme lower portion is in direct contact with the liquid, can be made of a cellulose or cotton linter based material, or of cotton linters alone, formed of fibers from 3 to 6 mm long, consisting of almost pure cellulose, a material similar to that used for known mosquito repellent tablets. The material making up the wick 14 contains from 10% to 30%, preferably 20%, mineral dust, in particular basalt. The heating element 10 advantageously consists of a thermistor which in turn is also protected by a covering. Another solution can be offered by a resistance heating element, also protected by a covering. The block 13, as described, which coaxially encloses the heating element 10, is housed in the extreme upper area of the box A or respectively of the cover 5, in which area a flat vertical wall 13′ belonging to block 13 itself runs parallel to a portion of the flat vertical wall 5′ of the cover 5. On the outside of the cover, and when the apparatus is ready for use, the upper free portion 14″ of the wick 14 is arranged with its wide flat wall, i.e. the widest wall, parallel and at a short distance d from the outer face of the above mentioned wall 5′ of the cover. Preferably, according to the width of the wick, a cut not better illustrated is made to allow the wick to reach within a short distance the above mentioned flat wall 13′ of the block 13. By maintaining a distance d , albeit short, between the corresponding longest flat wall 14‴ of the wick and the flat wall 13′ of the block 13, the wick or piece of cardboard is prevented from being damaged as a result of eccessive heating, and constant, uniform evaporation of liquid over the whole free portion 14‴ of the wick is ensured. An anular portion 1′ which emerges from the inside face of the base 1 of the apparatus in the box A supports a reservoir or container C, preferably made of pliable, transparent, artificial material. When new and unused, the container C is full of a liquid composed of substances which will be better specified below. The container C, which forms an integral part of the apparatus, can also be obtained separately, as a recharge. The anular recess 15 on the bottom of the container C fits the raised anular portion 1′ already described, which emerges from the base 1 of the box A, firmly setting the container concentric to the raised portion. The extreme lower portion 14′ of the wick 14 then reaches into the concave area defined by the aforementioned anular recess. This concave area serves to ensure that the wick is immersed during the final period of operation of the apparatus, avoiding wastage of even a small amount of liquid which, if it were distributed over the entire bottom surface and not collected therein, would wet the piece of cardboard only up to a much lower height than that required. A screw cap 17 (Fig. 4), mounted externally on the neck 16 of the container C ensures that the container C and also the wick 14 are perfectly sealed, when the container is not in use. Once again when the tank is not in use, provision is made for the cap 18 (Fig. 4) made of pliable material to be removeably fitted onto the neck 16, to prevent the liquid contained in the container from evaporating and thus condensing on the inner skirt of the external screw cap 17. As can be clearly seen in Figure 1, the portion 14″ of the wick 14 which protrudes upwards for a length s from a closing stopper 20 which will be better described later, is disposed with its smooth, flat, widest wall 14‴ parallel and at a short distance d from the portion of wall 5′ of the cover 5 or, when said flat wall 5′ of the cover has a cut (detail not shown in the drawing), parallel and at a short distance from the flat vertical wall 13′ of the block 13. The wick, which is made in the form of a piece of thin cardboard, is enclosed for a length L in an impermeable coating or sheath 19. As a result of this, the liquid in the container is absorbed solely by a short extreme lower portion of the wick 14′, not covered by the coating. The liquid rises in the wick solely by capillarity, since there is no play between the outer surface of the wick and the coating and thus no possibility of infiltration of liquid along the section L. More particularly, the chemical solution travels up the wick 14 by capillarity, starting from an area of the wick near the base of the container where there is a lower temperature, to reach an area adjacent to a heat source at a distance from said base and on the outside of said container, where there is a higher temperature. In said upper area the coating 19 of the wick 14 is surrounded by a closing device, in the form of an externally cylindrical stopper 20, which is tightly inserted into the neck 16 of the container C. The lower part of the coating 19 extends downwards in two teeth 19′ of the same length as the lower free portion of wick, said teeth ensuring that the portion of thin cardboard that protrudes therefrom is mechanically protected during movement and automated insertion into the container C of the wick unit formed by the wick 14 itself, the coating 19 and the stopper 20. The two teeth 19′ can conveniently be joined at their ends by a small bridge 19″ which creates a lower stop for the wick 14. A small continuous wall 21 extends from the upper wall of the stopper 20, surrounding the perimeter of the base of the protruding portion 14″ of the wick 14, creating a cup 21′ to collect the liquid that condenses and prevent it from escaping. In the upper part of the coating 19 a vent is provided that allows air to pass from the outside to the inside of the container C, to compensate for possible pressure changes that would produce undesired effects. The hole 22 comprises a vertical upper section 22′ which opens into the cup 21′ and a lower horizontal section 22″ which passes through the coating 19. By creating a wick unit (Fig. 5) in the form of a wick 14, a coating 19 which encloses the wick and a stopper 20, externally cylindrical, it is possible to use a wick 14, preferably made of thin cardboard, which is an excellent absorbent medium. Lastly, this unit affords maximum safety for the user, since the wick adheres closely to the sheath, making it impossible for liquid to escape from the container, even if it is turned upside down. The apparatus as shown in Figures 9-12 is of a similar design to that of Figures 1-8 and its various parts have been indicated increasing by at least ten the reference numbers used in Figures 1-8. It comprises a box A″ which is composed essentially of two assemblies, connected in a preferably permanent manner by means of couplings 37, 37′. However, in this apparatus the extreme upper portion of the wick is completely enclosed inside the box A″, the covering wall 44 of which is also provided with a plurality of openings 44′, 44″, 44‴ to aid evaporation of the liquid and ensure cooling of the container C′ in particular. Preferably, provision is made for the container to be inserted through a door 34 provided with a longitudinal opening 34′ to check the level of the liquid, and let in cooling air, this door being obtained in a single piece with the box A″. The container C′ is fixed at the base in the same manner as that foreseen in Fig. 1, while at the top, in the portion of the stopper 31, the container can optionally be spring engaged with the box. To this end, provision is made for a pincer-shaped connection 43 to be used, provided with two side claws 43′, 43″ each having teeth at the opposite ends, such as to engage elastically with the perimetral raised part 41 provided on the stopper 30 (Fig. 12). The connection 43 is obtained in a single piece with the box A″. A particular embodiment provides for the apparatus to be made without a door. In this case, the container is positioned in its housing, providing for this purpose pliable connections on the shell of the container itself or even a cylindrical shaped raised part at the base of the box, so that the tank can be inserted into it from above. The wick 14, in the form of thin cardboard or similar pre-cut material, can be inserted into the preformed coating or sheath 19, or made at the same time as the latter. In this case a mould is foreseen consisting of two half-moulds into which the pre-cut thin cardboard is inserted during the opening phase, these half-moulds are subsequently closed together and the plastic material is introduced into the free spaces, thus obtaining in a single operation the entire impermeable coating 19 around the wick 14. The chemical solution held in the container, to which 0.5% to 1% anti-oxidant is added, consists of an active ingredient suitable for repelling domestic insects, chosen from the group of synthetic pyrethroids listed: bioallethrin, allethrin, etok, esbiothrin, cypermethrin, alphamethrin, vaporthin, sumithrin, permethrin, or pyrethrum extract, alone or in combination, in a percentage of 2% to 8% in weight, particularly 3% to 5% in weight of esbiothrin, dissolved in a solvent chosen among the dearomatized aliphatic saturated hydrocarbons, having from 12 to 15 carbon atoms, alone or in combination, in a percentage from 98% to 92%, in particular 97% to 95% of C14. Special attention has been devoted to the choice of solvent, which has extremely favorable toxicological characteristics, being a very pure product devoid of aromatic nuclei. From what has been described the advantages of the apparatus in accordance with the invention compared with those of the prior art are clear. Thus, for example, the structure of the apparatus and particularly of the heating element and the wick, make it possible to insert the container C from the front, avoiding the difficulties of insertion from below, which could cause damage to the wick,

Claims: An apparatus to keep flying insects, particularly mosquitoes, away from people, comprising a box (A, A'') which encloses a container (C, C') containing an evaporable liquid chemical product which is drawn up by a wick (14, 54) after heating an upper portion (14'', 54'') of said wick by means of a heating device (10, 50), the box (A, A″) encloses said heat source (10, 50) provided with at least one flat wall (13′, 53′) set at right angles to the base of the container (C, C′) situated below, which contains the evaporable liquid and into which penetrates the wick (14, 54) the extreme upper portion of said wick (14', 54) is disposed near the flat wall (13′, 53′) of the heat source (10, 50), characterized in that the wick is coated with an impermeable material (19, 59) which covers almost its entire length (L), leaving free of coating the extreme lower portion of said wick (14′, 54′) and the extreme upper portion of said wick (14″, 54″) which protrudes from the container. An apparatus according to claim 1, characterized in that the wick (14, 54) has a rectangular cross section, in particular wide and flat. An apparatus according to claim 1 or 2, characterized in that the coating-free surface of the extreme lower portion of wick (14′, 54′) is very small compared with that of the actual coating of the wick, while the coating-free surface of the extreme upper portion of wick (14″, 54″) is larger than the lower one and has an enlongated shape. An apparatus according to any one of the claims from 1 to 3, characterized in that the wick (14, 54), surrounded by a coating (19, 59) for virtually its entire length, during operation of the apparatus the chemical solution held in the container (C, C′) advances by capillarity starting from an area of wick near the base of the container, where the temperature is lower, until it reaches an area adjacent to a heat source (10, 50) at a distance from said base and outside said container, where the temperature is higher. An apparatus according to claim 1, characterized in that the wick (14, 54) consists of an absorbent material, in particular cardboard or a cellulose and/or cotton linter based material, containing from 10% to 30% and preferably 20% mineral dust, particularly basalt. An apparatus according to any one of the preceding claims, characterized in that the coating (19, 59) of the wick (14, 54) in the upper area comprises a device for closing the container, in the form of an externally cylindrical stopper (20, 30) which can be tightly inserted into the neck (16, 56) of the tank (C, C′) and in that the wick (14, 54), the coating (19, 30) and the stopper (20, 31) form an inseparable unit. An apparatus according to claim 6, characterized in that above the stopper (20, 30) a raised part (21, 41) is provided that surrounds the base of the extreme upper portion of wick (14″, 54″) and creates a cup (21′, 41′) to collect condensed liquid. An apparatus according to claim 7, characterized in that in the upper part of the coating (19, 59) a vent (22, 42) is provided to allow air to pass from the outside to the inside of the container (C, C′). An apparatus according to any one of the preceding claims, characterized in that in its extreme lower part, the coating (19, 59) of the wick (14, 54) extends in the form of a series of two teeth (19′, 59′), possibly connected by a small bridge (19″, 59″), to protect the portion of wick (14′, 54′) that protrudes from the coating. An apparatus according to claim 1, characterized in that the box (A, A″) consists of two assemblies that form a single unit, one of which has a wall that serves as a door (4, 34), obtained in a single piece with one of said assemblies, and which is articulated along a vertical edge (2″, 32″) of a side (2′, 32′) of the same assembly. An apparatus according to claim 1, characterized in that an electrical power plug (6, 36) capable of rotating through an angle of 90° is mounted on the front wall (3, 33) of the box, the wires of said plug being connected to a switch, preferably luminous, and to an electrical heating element (10, 50) and possibly to a timer. An apparatus according to claims 1 and 4, characterized in that the heating element (10, 50) preferably takes the form of a casehardened wire-wound resistance, inserted inside an axial through-hole in a block (13, 53) of ceramic or appropriately plastic material, shaped like a parellelepiped, one longitudinal flat wall (13′, 53′) of said block being set at 90° to the base of the box and running parallel to the corresponding widest wall (14‴, 54‴) of the wick (14, 54). An apparatus according to claim 1, characterized in that the container (C, C′) is made of pliable material and is supported by the base (1, 51) of the box, from which base an anular rim (1′, 51′) protrudes, in order to create a complementary recess (15, 35) on the bottom of the tank into which the extreme lower portion (14′, 54′) of the wick reaches. An apparatus according to claim 1, characterized in that the chemical solution placed in the container is composed of an active ingredient such as the repell domestic insects, chosen from the group of synthetic pyrethroids listed: bioallethrin, allethrin, etok, esbiothrin, cypermethrin, alphamethrin, vaporthrin, sumithrin, permethrin, or pyrethrum extract, alone or in combination, in a percentage of 2% to 8% in weight, particularly 3% to 5% in weight of esbiothrin, dissolved in a solvent chosen among the dearomatized aliphatic saturated hydrocarbons, having from 12 to 15 carbon atoms, alone or in combination, in a percentage from 98% to 92%, particularly 97% to 95% of C14, with the addition of 0.5% to 1% of anti-oxidant.

Inventors: ZOBELE FRANCO, ZOBELE GIOVANNA, ZOBELE, FRANCO, ZOBELE, GIOVANNA
Applicants: ZOBELE IND CHIM, ZOBELE INDUSTRIE CHIMICHE S.P.A.
Application year: 1990
Main classification: A01M1
IPC codes: A61L9, A01M1