Abstract:
A heater fixture for use in an electrically heated cigarette smoking system having a source of electrical energy for heating a cigarette includes an inner wall or barrel having at least one opening through the inner wall extending from an outer peripheral surface to an inner surface of the inner wall, and at least one flow distributing element positioned within the at least one opening and extending inwardly from the inner surface. The flow distributing element or elements are provided with a plurality of openings that are in fluid communication with an interior of the heater.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a heater for use in an electrically heated cigarette smoking system. 
   BACKGROUND OF THE INVENTION 
   Previously known conventional lit cigarettes deliver flavor and aroma to the user as a result of combustion of tobacco. A mass of combustible material, primarily tobacco, is oxidized as the result of applied heat with typical combustion temperatures in a conventional cigarette being in excess of 800 degrees Celsius during puffing. 
   Lit-end cigarettes have some perceived drawbacks associated with them. Among them is the production of side stream smoke during smoldering between puffs, which may be objectionable to some non-smokers. Also, once lit, lit-end cigarettes must be fully consumed or discarded. Relighting a lit-end cigarette is possible but is usually an unattractive prospect for subjective reasons related to flavor, taste and odor. 
   Electrical smoking systems including electrically powered lighters and specially designed cigarettes that are adapted to cooperate with the lighters are disclosed in several commonly assigned U.S. patents, including U.S. Pat. Nos. 5,591,368, 5,878,752, 5,093,894, 5,225,498, 5,060,671, 5,095,921, 5,388,594 and 5,499,636, each of which is incorporated herein by reference. 
   In an embodiment of the lighter of U.S. Pat. No. 5,878,752, as shown in  FIGS. 1 and 2 , the smoking system  21  includes a cylindrical cigarette  23  and a reusable, hand-held lighter  25 . The cigarette  23  is adapted to be inserted and removed from an orifice  27  at a front end  29  of the lighter  25 . The cigarette  23  is disposed of after one or more puff cycles. The lighter  25  is preferably disposed of after a greater number of puff cycles than the cigarette  23 . The lighter  25  includes a housing  31  and has front and rear portions  33  and  35 . A power source  37  for supplying energy to heater elements  120  for heating the cigarette  23  is preferably disposed in the rear portion  35  of the lighter  25 . The rear portion  35  is preferably adapted to be easily opened and closed, such as with screws or with snap-fit components, to facilitate replacement of the power source  37 . The front portion  33  preferably houses heater elements and circuitry in electrical communication with a power source  37  in the rear portion  35 . The housing  31  is preferably adapted to fit comfortably in the hand of a smoker and, in a presently preferred embodiment, has overall dimensions of approximately 10.7 cm×3.8 cm×1.5 cm. The power source  37  is sized to provide sufficient power for heater elements that heat the cigarette  23 . The power source  37  is preferably replaceable and rechargeable and may include devices such as a capacitor, or more preferably, a battery. A substantially cylindrical heater fixture  39  for heating the cigarette  23 , and, preferably, for holding the cigarette in place relative to the lighter  25 , and electrical control circuitry  41  for delivering a predetermined amount of energy from the power source  37  to cigarette heater elements  120  of the heater fixture  39 , are preferably disposed in the front  33  of the lighter. 
   The plurality of metallic heaters  120  are disposed in a configuration that slidingly receives a tobacco rod portion of a cigarette. One of the many advantages of such a smoking system is the reusability of the lighter for numerous cigarettes. In the heater fixture disclosed in U.S. Pat. No. 5,878,752 and shown in  FIGS. 1 and 2 , a cigarette would be inserted through the tapered opening at the right side of  FIG. 2  into a substantially cylindrical space of the cigarette heater fixture defined by a ring-shaped cap  83  having an open end for receiving the cigarette, a cylindrical air channel sleeve  87 , an outer sleeve  84 , a heater assembly including the heater blades  120 , and electrically conductive pins or leads  104 A and  104 B. The spacer  49  stops the cigarette in a desired position in the cigarette heater fixture such that the heater blades  120  are disposed in a snug fit around the outer circumference of the cigarette. The heater fixture disclosed in U.S. Pat. No. 5,878,752 shows an air channel sleeve  87  through which air can flow axially in order to reach the point where the heater blades  120  contact the cigarette. Gaps  125 ,  126  and  130  can provide pathways for the air to be drawn into contact with the inserted cigarettes. 
   SUMMARY OF THE INVENTION 
   An embodiment according to the present invention provides a desirable improvement in air flow distribution to heater blades of an electrical smoking system, which results in an increase of the total aerosol delivery of the system. 
   In a modification of the heater disclosed in U.S. Pat. No. 5,878,752, the air flow channel sleeve  87  can be eliminated and air directed to the heater blades through radial holes in the sleeve  200 . Air can reach the outside of sleeve  200  after passing through an opening or openings in the housing  31  of the lighter  25 . Although not shown in  FIG. 1 , such openings would typically be provided through the housing  31  at the front  33  of the lighter  25 . It has been discovered that side holes through the sleeve surrounding the heater blades may result in channeling of the air flow over a limited area of the heater. With limited air flow to the heater blades and the cigarette, the pyrolysis of the cigarette is also limited and the total particulate matter produced in the generated aerosol is restricted. Accordingly, limitations in the air flow to the heater blades can result in the heater failing to produce sufficient aerosol to provide a smoker with the desired flavors and aromas. 
   A heater fixture for use in a smoking system having a source of electrical energy for heating a cigarette according to an embodiment of the invention includes an inner wall, said inner wall having at least one opening through the wall extending from an outer peripheral surface to an inner surface of the wall, and at least one flow distributing element positioned within said at least one opening and extending inwardly from the inner surface. The at least one flow distributing element includes a plurality of openings that are in fluid communication with an interior of the heater fixture. A plurality of heater elements are arranged in the interior of the heater fixture within the inner wall, and fit snugly around the outer circumference of a cigarette inserted into the heater fixture. The openings from the flow distributing element into the interior of the heater fixture extend radially outward from the central axis of each flow distributing element and ensure that the air flow will be mixed within the heater fixture as the air is directed in different directions through the holes from the flow distributing element. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of an electrical lighter. 
       FIG. 2  illustrates a side cross-sectional view of a heater fixture surrounded by an inner barrel or sleeve and associated heater element. 
       FIG. 3A  illustrates a side cross-sectional view through a flow distributing element according to an embodiment of the invention. 
       FIG. 3B  is a cross-sectional view taken in the direction of arrows A—A in  FIG. 3A  of a flow distributing element according to an embodiment of the invention. 
       FIG. 4  illustrates an inner barrel or sleeve for the heater in an electrically heated cigarette smoking system and having two side holes through the barrel to provide air flow into the heater. 
       FIG. 5  and the enlarged view in  FIG. 5A  illustrate the inner barrel of  FIG. 2  modified to include two flow distributing elements according to an embodiment of the invention placed through the side holes. 
       FIG. 6  illustrates a side cross-sectional view of an inner barrel for a heater having flow distributing elements according to an embodiment of the invention and an outer barrel having openings positioned radially outward from the flow distributing elements. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   A heater fixture of an electrical smoking system having improved air flow is described below. Electrically heated cigarette smoking systems are described in greater detail in U.S. Pat. Nos. 5,388,594 and 5,878,752, which are hereby incorporated by reference in their entireties. The fixture used in the electrically heated cigarette smoking systems described in the above patents is shown in  FIGS. 1 and 2  of the present application. A specially designed cigarette is adapted to be inserted in and removed from an orifice  27  at a front end of the heater fixture  39 . The heater fixture  39  is preferably substantially cylindrical, and holds a cigarette in place relative to the electrically heated cigarette smoking system in which the heater fixture is supported. Electrical control circuitry can also be provided within the electrically heated cigarette smoking system for delivering a predetermined amount of energy from a power source to the cigarette heater elements  120 , shown in  FIG. 2 . A generally circular, terminal end hub  110  is fixed, e.g., welded, to be disposed within the interior of the cigarette heater fixture  39 , e.g., is fixed to a spacer  49 , as shown in  FIG. 2 . 
   The heater fixture  39  includes a plurality of radially spaced heater blades  120  supported to extend from the hub  110 , as shown in  FIG. 2 . The heater blades  120  are individually energized by a power source under the control of electrical circuitry (not shown). 
   The heater elements  120  can comprise any suitable heater element for heating tobacco to evolve tobacco flavors. For example, the heating system can comprise any of the resistance and induction heating systems disclosed in the above-referenced patents. 
   A cigarette is inserted in the orifice  27  of the heater fixture  39 , and into a substantially cylindrical space of the heater fixture  39  defined by a ring-shaped cap  83  having an open end for receiving the cigarette, and a cylindrical sleeve  87 , such as shown in  FIG. 1  except that the axial air passageways shown in  FIG. 1  are no longer provided in an embodiment according to the invention. The heater fixture  39  also can include an outer surface or barrel, which preferably also forms the outer housing  31  of the lighter  25 , a heater assembly including the heater blades  120 , electrically conductive pins or common leads  104 A,  104 B, which serve as common leads for the heater elements of the heater assembly, and the spacer  49 , to which the terminal end hub  110  is fastened. 
   The heater fixture  39  according to an embodiment of the present invention, as shown in  FIG. 5 , comprises an inner cylindrical sleeve or barrel  200  concentrically surrounding the heater blades  120  that is provided with openings through which flow distributing elements  20 , shown more clearly in  FIG. 5A , are inserted. As shown in  FIG. 6 , the inner barrel or sleeve  200  is concentrically surrounded by an outer barrel or sleeve  300 , that is also provided with openings  302  and  304 , which are preferably placed approximately radially outward from the openings in the inner barrel or sleeve  200 . The outer barrel or sleeve  300  preferably forms the outside of the lighter  25 , or housing  31  shown in  FIG. 1 . 
   It has been found that a primarily transverse or radial air flow relative to the inserted cigarette results in a more desirable aerosol flow radially inward from the cigarette heater blades. Flow distributing elements  20  shown inserted through side holes in the inner barrel  200  in  FIGS. 5 ,  5 A and  6 , and shown in detail in  FIGS. 3A and 3B , help to ensure that air flow entering the inner barrel  200  is distributed evenly amongst the heater blades within the inner barrel  200 . 
   As shown in  FIGS. 3A and 3B , a flow distributor  20  is substantially a hollow, closed-end cylinder with four holes through its wall  20   c  near the closed end of the cylinder. The holes  30   a ,  30   b ,  30   c , and  30   d  can be located through the wall  20   c  of the flow distributing element near the closed end  20   a  of flow distributing element  20  and distributed evenly around the circumference of the flow distributing element. In the embodiment shown in  FIG. 3B , the holes are located 90 degrees apart, although other alternate configurations are possible and contemplated within the scope of the invention. 
   As shown in  FIGS. 5 and 5A , two flow distributing elements protrude through the side walls of the inner barrel or sleeve  200 , spaced 180 degrees from each other, and extend radially inward toward the interior of the heater fixture. The openings  30   a ,  30   b ,  30   c ,  30   d  are positioned in the interior of the inner sleeve  200  such that air flowing through the flow distributing elements  20  is distributed more uniformly inside the heater fixture  39 . The openings shown in  FIG. 3B  force air to be channeled in four different directions as it exits from the flow distributing element  20  into the interior of the inner sleeve  200 . 
   An outer barrel or sleeve  300  preferably forms the outer housing of the lighter, concentrically surrounds the inner sleeve  200 , and is provided with openings  302 ,  304  that are preferably positioned radially outward from the location of the flow distributing elements  20  through inner sleeve  200 . Ambient air on the outside of the outer barrel  300  enters through the openings  302 ,  304  and is directed into the flow distributing elements  20  when a smoker draws upon a cigarette inserted within the heater fixture  39 . The outer barrel or sleeve  300  preferably forms the outer housing of the lighter containing the heater fixture  39 , such that openings  302 ,  304  open to the outside, ambient air. 
   The improved air flow that is caused by air entering into the space around heater blades  120  after being distributed by passage through the flow distributing element  20  results in an increase in the total delivery of aerosol caused by the heating of the cigarette inserted within heater blades  120 . The improvement in delivery of total particulate matter caused by the heating of tobacco in proximity to heater blades  120  has been measured to be approximately 10% greater than the total particulate matter delivered by a heater fixture  39  that does not include the advantage of the flow distributing elements  20  for better air flow distribution to and around the heater blades  120 . 
   Many modifications, substitutions and improvements may be apparent to the skilled artisan without departing from the spirit and scope of the present invention as described in and defined herein and in the following claims. In particular, the number of openings through the flow distributing element wall is not limited to four and the openings can be distributed at circumferential positions around the distributing element other than at 90 degrees. Additionally, although two flow distributing elements  20  are shown at approximately 180 degrees from each other through the wall of inner sleeve  200 , the number of flow distributing elements can vary as well as their locations through the wall of the inner sleeve or barrel  200 . 
   While this invention has been described in conjunction with the exemplary embodiments outlined above, many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments of the invention may be made without departing from the spirit and scope of the invention.