Patent Publication Number: US-10772359-B2

Title: Electronic cigarette

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. patent application Ser. No. 14/516,444 filed Oct. 16, 2014 and now pending, which is a continuation of International Application No. PCT/CN2012/000530, filed Apr. 18, 2012, each of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Electronic cigarettes are increasingly used by smokers as a substitute for real tobacco cigarettes. In general, electronic cigarettes use a wire coil heater to vaporize liquid nicotine, or other liquid substances. The user&#39;s inhalation on a mouthpiece may be detected by a sensor, causing an electronic circuit to supply electrical current from a battery to the heater. The liquid contacts the wire coil heater, which creates the vapor or mist. The user&#39;s inhalation typically also draws ambient air into one or more inlets in the electronic cigarette housing. The vapor is entrained in the air flow moving through the housing and is inhaled by the user. 
     Electronic cigarettes have many advantages over real tobacco cigarettes. Initially, the risks of lung cancer associated with real tobacco cigarettes is largely avoided, as the tar and other chemicals in tobacco linked to lung cancer are simply not present in an electronic cigarette. Electronic cigarettes generate vapor or mist, and not smoke. Consequently, there is no comparable second-hand smoke problem with use of electronic cigarettes. In addition, since there is no burning material in electronic cigarettes, the risk of fire is eliminated. 
     Many electronic cigarette designs have been proposed and used, with varying degrees of success. Existing designs though have various disadvantages, including short life, poor atomization, nonuniform vapor caused by different sizes of liquid drops, and overheated vapor. Accordingly, there is a need for an improved electronic cigarette. 
     SUMMARY OF THE INVENTION 
     A new electronic cigarette has now been invented that provides significant improvements over existing designs. In this new electronic cigarette, a mesh element is in contact with liquid storage. A heater is spaced apart from the mesh element and positioned to heat air which flows through the mesh element. The heated air vaporizes the liquid in or on the mesh. The vapor is inhaled by the user. 
     In another aspect, the heater may be positioned within a heater housing having an air passageway aligned with a central opening extending through the liquid storage. Alternatively, an annular flow path around the outside of the liquid storage may be used. 
     The present electronic cigarette may include a battery in the housing electrically connected to a flow sensor, a circuit board and the heater. A flow path through the housing may be formed via one or more inlets in the housing, a passageway containing the heater, and a central opening extending through the liquid storage to an outlet. 
     In a separate aspect, a method of vaporizing a liquid in an electronic cigarette includes conducting liquid from a liquid storage to a mesh element. Electric current is supplied to a heater, optionally in response to sensing inhalation on the outlet or mouthpiece of the electronic cigarette. The heater heats air and the heated air is conducted through the mesh element, with the heated air vaporizing liquid on or in the mesh element. The vaporized liquid is entrained with the heated air and may then flow through or around the liquid storage to the mouthpiece. 
     Other and further objects and advantages will become apparent from the following detailed description which is provide by way of example, and is not intended as a statement of the limits of the invention. The invention resides as well in sub-combinations of the elements and steps described. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, the same reference number indicates the same element in each of the views. 
         FIG. 1  is a section view of an electronic cigarette. 
         FIG. 2  is an enlarged detail view of components of the electronic cigarette shown in  FIG. 1 . 
         FIG. 3  is a schematic section view of an alternative embodiment. 
         FIG. 4  is a perspective view of a component of the design shown in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Turning now in detail to the drawings, as shown in  FIGS. 1 and 2 , and electronic cigarette has a housing  10  which optionally may be provided with a front section  12  attached to a back section  14  via screw threads or other attachment. A battery  16  and a circuit board  24  may be contained within the front section, with the circuit board electrically connected to a flow sensor  20  and to a heater coil  40 , as further described in U.S. Patent Publication No. US2012-0111347 A1, incorporated herein by reference. A liquid storage  34  is contained within the back section  14  of the housing  10 . The liquid storage  34  may be a fiber material, provided loose in bulk directly into the back section  14  of the housing, or it may be provided in or as part of a separate component or cartridge. The liquid storage may contain liquid nicotine, or another liquid for vaporization and inhalation. Other materials such as foam or porous metals or ceramics may optionally be used as the liquid storage  34 . 
     The heater coil  40  may be positioned within a passageway  38  extending through a heater support  28 . The heater housing, for example, a ceramic material, is fixed in place within the housing. An optional collector  30  may be attached to the back end of the heater support  28 , with the passageway also extending centrally through the collector  30 . The collector  30 , if used, may be made of SILASTIC® silicone elastomers, or other high temperature inert silicon elastomers or plastic materials. 
     A mesh element or screen  32  on the front end of the liquid storage  34  is spaced slightly apart from the back end of the collector  30 , by a dimension BB ranging from about 0.5 to 2 or 4 mm, and typically about 1 mm. The mesh  32  may be fiberglass, or other porous material, which the liquid in the liquid storage, such as liquid nicotine, can wick onto or through. The mesh  32  may have a thickness or dimension AA in  FIG. 2  ranging from about 0.1 to 2 mm, 0.2 to 1 mm, or 0.3 to 0.6 mm, with a 4 mm thickness typical. 
     An opening  36  extends from the mesh  32  centrally through the liquid storage  34  to an outlet  42  at the back end of the housing  10 . A flow path may be formed through the housing  10  via one or more inlets  18 , a through opening in the sensor  20 , the flow tube  22 , the passageway  38  and the opening  36  leading to the outlet  42 . Except as specified, the positions of the elements shown in the drawings is not critical, and the elements may be rearranged as needed or desired. 
     Referring still to  FIGS. 1 and 2 , in an example of use, the user inhales on the outlet  42 . The sensor  20  detects the inhalation and supplies electrical current to the heater coil  40 . Air is drawn into the flow path in the housing through the inlets  18 . The flowing air passes through the passageway  38  and is heated by the heater coil  40 . The amount of heating may vary by design. Air temperatures of 200 to 300° C. at the exit of the passageway, as one example, may be used by adjusting the power of the heater and the air flow characteristics through or past the heater. The collector  30 , if used, may help to collect and direct the heated air to the mesh  32 . The collector  30  may also be used to space the heater coil  40  and the heater support  28  apart from the mesh  32 . The collector may optionally be made part of the heater support  28 . 
     The mesh  32  is provided as a thin sheet or layer, and has a sufficiently open structure, so that the heated air can pass through without excessive flow resistance. The mesh  32  may be a sheet or layer of loose fiberglass, fiberglass fabric or similar material that can wick and hold liquid on the surface of the fibers, and/or in the gaps between the fibers, and also allow air to flow through. A heat resistant foam material may alternatively be used in place of the mesh. 
     The heated air flows through the mesh  32 . This heats liquid in or on the mesh, which atomizes or vaporizes the liquid. The vapor is entrained in the heated air, which continues flowing from the mesh  32  through the opening  36  and the outlet  42 , with the mixture of air and vapor inhaled by the user. The heated air may cool considerably as it passes through the mesh  32  and the opening  36 , so that the user inhales air from the outlet at a comfortable temperature of e.g., 25 to 50° C. 
       FIGS. 3 and 4  show an alternative design having a similar operation, but with the airflow path extending around the outside of a liquid storage element  54 , rather than through the liquid storage, as in  FIGS. 1 and 2 . In the alternative design of  FIGS. 3 and 4 , the liquid storage is surrounded by an annular passage  56 , leading from a woven or mesh tube  52  to the outlet  42 . As also shown in  FIGS. 3 and 4 , the mesh tube  52  has a plate section  62  in contact with the liquid storage. A neck section  64  of the mesh tube  52  extends from the plate section  62  towards the heater  28 . Liquid in the liquid storage  54  wicks through the plate section and into the neck section  64 . Heated air diffusing radially outwardly through the neck section vaporizes the liquid creating a mist or vapor, which is drawn through the flow path  56  and inhaled by the user. The woven tube  52  may be produced by twill weave, and then cut with a hot blade, to prevent unraveling of cut end. Of course, the thin flat mesh component  32  shown in  FIG. 2  may also be used in an embodiment having the annular passage  56  as shown in  FIG. 3 . 
     In the designs described above the liquid does not come into direct contact with the heater coil. This avoids the loss of heating efficiency resulting from deposits and liquid residue collecting on the heater coil  40 . It also allows for longer heater coil life, as thermal shock to heater coil, and corrosion are reduced. Vaporization is also improved because the liquid is vaporized at lower temperatures. The heater coil itself may operate at temperatures in the range of 500° C. This can cause chemical changes in the liquid as it is vaporized. By avoiding contact between the heater coil and the liquid, and by vaporizing the liquid using heated air, chemical changes occurring during vaporization may be reduced. 
     In addition, since the heater coil  40  does not come into contact with the liquid, the heater coil may be plated with corrosion resistant materials, such as silver or nickel-chromium. Use of these types of materials, which would be degraded if contacted by the liquid, prolongs the life of the heater coil. Since the life of the heater coil can be much longer, the heater coil can be made as a reusable component, rather than be a disposable item as is common with existing designs. This allows for reduced costs. 
     With existing known electronic cigarettes, the heating device or coil must heat the nicotine liquid first, before the liquid can be vaporized. The present electronic cigarettes omit this initial step, as the heater coil  40  heats air, and not liquid. Consequently, the new designs described here also achieve faster vaporization in comparison to known designs. 
     Thus, novel designs have been shown and described. Various changes and substitutions may of course be made without departing from the spirit and scope of the invention. The invention, therefore, should not be limited, except by the following claims and their equivalents.