Smoke generator with combined spacer and wetting wire and toy smoke-ring gun using same

Information

  • Patent Grant
  • 6826355
  • Patent Number
    6,826,355
  • Date Filed
    Monday, April 22, 2002
    22 years ago
  • Date Issued
    Tuesday, November 30, 2004
    20 years ago
Abstract
A toy gun produces a series of traveling smoke rings. It has a smoke chamber fed with smoke from a battery-powered electrical resistance generator. An elastic, edge-mounted diaphragm extends across at least a portion of the rear of the smoke chamber. A reciprocating actuator movable in response to a trigger strikes the diaphragm to eject a smoke ring through an orifice in the opposite wall of the smoke chamber. The smoke generator includes a supply tank of a suitable liquid and a source of variable pressure to drive the liquid through a narrow annular clearance to the heater where it is rapidly vaporized. The generator includes a pair of concentric tubes that define the annular clearance and an electrical resistance heating element mounted on one of them at a point spaced from the supply tank. The generator also includes a spacer and a member that increases the length of the flow path of the fluid driven through the narrow annular gap. The spacer establishes and maintains a generally uniform clearance circumferentially. A spiral wound wire preferably acts as the spacer and establishes a helical fluid flow path of increased length as compared to a linear, axial fluid flow path.
Description




FIELD OF THE INVENTION




The invention generally relates to apparatus for producing smoke, steam or fog, and more particularly, to a toy gun that produces one or more traveling smoke rings when fired.




BACKGROUND




Various toys are known that utilize smoke, steam, and fog (herein, collectively, “smoke”) generators, and a variety of generators for producing smoke for toys, theatrical productions, and the like are also known. See, e.g., U.S. Pat. No. 3,891,826. Liquid mixtures specifically designed for use in such generators are also known. See, e.g., U.S. Pat. No. 3,342,746.




Toy guns have captured the popular imagination for many years. Metcalf, E. W. and Maresca, F.,


Ray Gun


(1999) Fotofolio, Inc., New York, N.Y. is devoted to one type of toy gun, a ray gun. In particular, smoke-producing toy guns are known. U.S. Pat. No. 2,855,714 describes a toy gun that produces smoke rings through the detonation of percussive caps within the gun casing.




While the visual effects and realism of smoke-producing toy guns are significant advantages, a number of drawbacks have limited their commercialization. For example, many prior smoke generators for toys employ mixtures that are not always completely safe. In particular, many oils and oil-based mixtures for making smoke have not been approved for human use. Children may be especially prone to injury from exposure to or mishandling of such fluids, or to heaters used to vaporize liquids to make smoke.




Many prior generators, such as those employed in model railroads, have an open smoke producing device, usually a chimney on an engine, that operates continuously. This arrangement is not conducive to producing smoke rings. It also can be sensitive to orientation—a smoke generator for a fixed, upright smokestack on a model train may not function, or function well, when used in a toy that may assume orientation other than upright. Further, continuous smoke production and the power requirements of such production also militate against the portability of the toy or other device using smoke.




Prior toy guns have used detonation of percussion caps to make smoke. This arrangement is portable and does not require electrical power, but it clearly may not be suitable for use by or near children because of the harmful percussion cap explosions. Percussion caps also produce the noise of a cap explosion, which may be a negative attribute to many.




U.S. Pat. No. 3,342,746 to Seuthe discloses oil-based fluids and a generator for producing smoke. As noted above, such fluids may not be completely without adverse health reactions, particularly when used in closed rooms. In particular, exposure to such fluids in aerosol form can produce significant eye, nose and throat discomfort.




A later Seuthe patent, U.S. Pat. No. 3,891,826, describes a smoke generator that relies on a capillary action to draw the liquid from a central, open-top reservior to a heated region where it vaporizes to provide a smoke or fog. Such generators require an upright orientation for optimal use (due to the effect of gravity on a capillary action that feeds fluid to a resistance heater) and to avoid fluid loss, e.g., due to an outflow from the fluid reservoir. Also, use of electrical resistance wires or coiled wires in many prior generators to vaporize a fluid has presented unacceptable power requirements for portable devices operated with batteries. With model railroads, in contrast, power is typically supplied by household electrical current through a step-down transformer. Further, the narrow clearances and related manufacturing requirements make the Seuthe generator comparatively difficult to manufacture.




It is therefore a principal object of this invention to provide a smoke generator that is portable, safe, fast-acting for non-continuous operation, has comparatively low power requirements, and is substantially orientation insensitive.




Another principal object of this invention is to provide a portable, battery-powered smoke-ring gun that uses electrical resistance heating to produce the smoke and a mechanical heater accessory that significantly enhances the efficiency and volume of the smoke production.




A further object is to provide a smoke ring gun with the foregoing advantages of the smoke generator of the present invention that also has a favorable cost of manufacture.




A still further object is to provide a smoke ring gun with the foregoing advantages that can generate smoke from a water-based liquid.




SUMMARY OF THE INVENTION




The present invention provides apparatus for producing smoke and a toy gun that fires to produce smoke in a traveling ring shape, and in particular is capable of producing a succession of smoke rings traveling from the gun in its direction of aim. A particular toy gun includes a smoke chamber fed by an electrical resistance smoke producing generator. The chamber has an elastic, edge-mounted diaphragm, or equivalent moveable member, that co-acts with the chamber and an outlet orifice formed in a front wall of the chamber to produce the smoke rings. The smoke generator used in the gun is preferably the smoke generator of the present invention. The generator and toy gun can operate with water-based smoke-producing liquids.




The invention includes a smoke generator that includes:




a) a supply tank that holds the liquid,




b) a source of variable fluid pressure (e.g. air) in sealed fluid communciation with the supply tank for increasing and decreasing fluid pressure in the tank to feed the liquid to and from a heating unit;




c) a first tube with a first end entering into the supply tank, and a second smoke outlet end;




d) a heater positioned at least partially within the first tube for vaporizing the pressurized liquid driven by an increase in the pressure into a narrow annular region between the heating element and the surrounding tube; and




e) a spacer that secures a generally uniform radial spacing along the annular region between the outer-surface of the heater and the inner surface of the first tube.




The spacing is such that the pressure increase feeds the fluid to a region adjacent the heater on rapid vaporization, but does not usually overflow the tube, or have a sufficient thermal mass that rapid vaporization of the liquid is difficult. Typically, the heater is an electrical resistance wire that is coiled. When used in a toy gun of the present invention, the variable fluid pressure source is preferably a bulb made from a pliable material, such as rubber, or the like.




The resistance coil is preferably sealed within a heat conductive tube, e.g., a glass tube. In most invention embodiments, the heating element will be suspended in the first tube, usually by means of one or more lead wires to the electrical resistance wire. Also in the preferred form, a second metal tube concentrically surrounds the first tube for mechanical protection and insulation. Overflow and condensate that flow to the bottom of the generator are drained to a closed collection compartment.




A spacer, preferably in the form of a wire that is spiral wrapped around the glass envelope of the heater, maintains a generally uniform, circumferential spacing between the glass envelope and the surrounding first tube. The diameter of the wire is in the range of about 25 to about 75% of the width of the annular gap when the heater is centered in the first tube. For a circumferentially uniform gap of about 0.004 inch (measured radially), the wire preferably has a diameter of about 0.002 inch. The width should also be sufficient not only to control the uniformity of the spacing, but also to force the fluid flowing over the heater to follow a generally helical, or upwardly swirling, flow path. The combination of even radial spacing, an increased flow path over the heater, and it is believed, the turbulence in the fluid flow created by the presence of the wire in the flow path, all combine to increase the efficiency and volume of smoke production, other factors being constant.




The wire provides some degree of lateral position control through its physical presence in the gap and, in part, through a degree of movement due to the inherent spring action of the wire. The wire is formed of a material that is non-corrosive in the smoke generation environment. Stainless steel is preferred. The wire preferably has a circular cross-section.




This “wetting wire” preferably has from 2 to 36 turns with a diameter of a few mils wrapped over an axial length of about one inch, e.g., for a smoke ring gun application. Preferably there are 12 to 14 turns with the wire diameter about half the radial spacing. The wetting wire is secured axially by any convenient mechanical expedient to surround the heater coil within the envelope, and preferably extending for a distance below it. Preferably, the upper end of the wire is directed down over the outer surface of the first tube and clamped by an O-ring. The lower end of the wetting wire is wrapped onto the lower electrical lead for the heating coil.




The glass envelope of the heater is preferably formed of a cylinder of glass sealed at its ends with a high-temperature epoxy plug. Lead wires to the heater coil pass through, and are secured by, the plugs.




In a preferred embodiment, the smoke generator is positioned below and in fluid communication with the first smoke chamber of a toy smoke ring gun. Also, the smoke generator is actuated by 1) an electrical on-off switch that controls the flow of current from a battery or batteries, preferably secured in a handle or grip portion of the gun body, to the electrical resistance wire, and 2) a variable pressure liquid supplier, e.g. a flexible rubber bulb that is squeezed by the user to create a positive air pressure in a liquid supply tank, thereby forcing smoke liquid to the heater. Typically, this produces an instant burst of smoke filling the smoke chamber. When the pressurized fluid supplier is disengaged (released), negative pressure is delivered to the tank, which in turn clears all, or most, of the smoke liquid from the generator.




The invention also provides a toy gun that includes at least one and preferably all of the following components:




a) gun body,




b) a smoke chamber at one end of the gun body and having spaced apart front and rear walls and a side wall,




c) a member movable axially to form pressure waves within the smoke chamber forming at least a portion of said rear wall,




d) an orifice in said front wall,




e) a smoke generator operably coupled to the smoke chamber of the type described in summary form above; and




f) an actuator, preferably an elongated member mounted in the gun body for an axial sliding movement and spring-driven toward a forward position where it strikes the diaphragm to create a pressure wave inside the smoke chamber that interacts with the orifice to produce a traveling smoke ring.




The smoke generator is battery-powered and has an electrical resistance heater that vaporizes a portion of a liquid from a supply of the liquid carried in the gun. The movable member is preferably a latex rubber sheet of generally circular configuration, but is edge-mounted, preferably with a low tension across the sheet. The actuator head is preferably rigid. The drive-spring is preferably adjustable to vary the strike force of the actuator on the diaphragm. The actuator is operatively coupled to a trigger that cocks, and then releases, the actuator to move under the forces of the compressed spring. The smoke generator preferably uses a flexible bulb, activated by a second trigger as a hand grip, to produce smoke for the smoke chamber. A light source is provided in the smoke chamber. It can be actuated by the same switch that powers the smoke generator, although in other embodiments the light source may be controlled by a separate switch.











BRIEF DESCRIPTION OF THE DRAWINGS




Still other features, advantages and aspects of the present invention will become more apparent from a description of illustrative embodiments hereinafter, when read in conjunction with the drawings of which:





FIG. 1

is a view in side elevation, showing a toy smoke-ring gun according to the present invention, and a succession of traveling smoke rings produced by the gun;.





FIG. 2

is a view in vertical cross-section of a preferred embodiment of a smoke-ring gun according to the present invention;





FIG. 3

is an enlarged view in vertical cross-section of the smoke generator shown in

FIG. 2

;





FIG. 4

is a detailed view in vertical section corresponding to

FIG. 3

showing an alternative form of a smoke-generator according to the present invention; and





FIG. 5

is a detailed view in vertical section of a portion of an alternative improved smoke generator of the type shown in

FIGS. 2-4

and including a spacer and wetting wire wrapped on the heater envelope.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS





FIGS. 1-3

show a toy smoke-ring gun


10


according to the present invention and a succession of smoke rings


12


produced by the gun


10


. The rings


12


are ejected from a smoke collection chamber


14


located at the front of the gun


10


and secured, e.g. by a set of struts


11


, on a gun body


16


. The rings travel axially in the direction of arrow


18


. In the preferred form shown, the gun


10


is in the form of a pistol with a hand grip


20


and a trigger


22


. As will be described below, the form, number and speed of the smoke rings are all adjustable. Smoke is produced by a user of the gun on demand to fill the chamber


14


. Rings can be generated automatically, but preferably one ring is produced with each pull of the trigger


22


provided that there is sufficient smoke accumulated in the chamber


14


. The gun


10


is preferably powered by batteries


24


. The operation of the gun


10


is invariant to its orientation. It can be placed on its side when not in use without spilling a liquid supply held in a tank


32


and vaporized in small volumes to create the smoke. However, when not in use, in its presently preferred form shown in

FIGS. 2 and 3

, the gun


10


rests on a flat-bottomed base


28


found at the bottom of the hand grip


20


and serving as a holding compartment for multiple batteries


24


. The weight of the batteries, and the configuration of the base, provide a stable support for the gun


10


when it is not in use.




A central feature of the present invention is an on-demand, battery-powered, orientation-insenstiive, smoke generator


30


shown in detail in

FIG. 3

, and in an alternative form, in

FIG. 4

(like parts being marked with the same reference number in both figures). The smoke-ring generator


30


includes the tank


32


that holds a supply of a liquid


34


to be vaporized, an air-filled rubber bulb


36


to pump the liquid to a heating region, and a heater


38


, preferably one using an electrical resistance heating wire. The wire is preferably coiled, and will be referred to herein as a “coil”, but the term “coil” is not limited to a resistance heater element that is actually in a helical or coiled form. As shown, the generator is in its preferred orientation, with arrow


31


indicating the vertical.




A tube


40


is mounted generally vertically through the upper wall of the tank


32


so that the bottom of the tube


40


ends slightly above the bottom of the tank. A high temperature glass tube


42


of the heater


38


is mounted coaxilly inside the metal tube


40


, with a narrow annular space


43


therebetween. The bottom of the glass tube is above the top of the liquid


34


in the tank


32


. The top of the glass tube


42


extends above the top of the metal tube


40


. Inside the glass tube


42


an electrical resistance wire or coil


44


is positioned so that the top of the coil is just below the top of the metal tube


40


, and the bottom of the coil is well above where the metal tube


40


goes through the tank


32


. The position of the coil limits heat transmission principally to the area of connection between the metal tube


40


and the tank housing


32


. The glass tube


42


extends above the metal tube


40


so that an electrical lead


46


cannot touch the metal tube


40


. Both ends of the glass tube


42


are fused so that the tube and leads are sealed and impervious to moisture. Air is preferably not evacuated from the glass tube


42


for better heat conduction to the outer surface, but operation with some degree of a vacuum in the tube is possible. A bottom lead


48


extends through the glass tube


42


and out the end of the metal tube


40


so that it can be easily connected to the bottom outside of the metal tube


40


. A durable electrical connection


47


is connected to the outside of the metal tube


40


and extended outside the tank


32


.




A larger metal tube


50


, preferably formed of brass, is mounted coaxially outside of the metal tube


40


so that the top of the metal tube


50


extends above the top of the glass tube


42


, and the bottom of this metal tube


50


extends just above the bottom of the glass tube


42


. This outer metal tube


50


acts as an insulator, protects the inner, relatively delicate, tubes


40


,


42


from damage, and protects against human contact with any components at the high heat of the coil


44


. Also, the tube


50


becomes an electrical conductor so that the lead


46


from the top of the coil


44


so that a durable electrical lead


52


can be connected to the tube


50


.




The liquid


34


is loaded through the tank filler hole


34




a


. A rubber stopper


54


seals the tank


32


so that no air or fluid can escape. The rubber bulb


36


is mounted on an air delivery tube


56


that extends to an air-tight connection


58


to the tank


32


. Because the only vent to atmosphere from the heater is the tube


40


, the liquid


34


does not flow out of the heater when the gun


10


is laid on its side, or even when it is held upside down, just as olive oil will not pour easily from a can that has only one small hole punched in its upper end. This characteristic of the smoke generator is referred to herein as “closed”.




Although the close fit between the glass tube


42


and the metal tube


40


could be considered a capillary space, the opposite effect is desired. When the rubber bulb


36


is squeezed, air is delivered to the tank


32


which in turn exerts positive fluid pressure on the liquid


34


. This liquid is pumped up into the metal tube


40


and over the glass tube


42


where it is vaporized rapidly by the high heat produced by the coil


44


. When the rubber bulb


36


is released, negative pressure is delivered to the tank


32


. This allows the coil


44


to rapidly heat to its highest temperature without loss of heat to the liquid. Also, the evacuation of the fluid from the region around the coil


44


in response to a decrease from the increased (pumping) fluid pressure conserves power through an increase in electrical resistance produced by the increased heat of the coil when the heat sink of the surrounding liquid is withdrawn. This conservation of power is important in that the heater


38


is powered by battery.




In addition, when fluid is delivered to the metal tube


40


by squeezing the rubber bulb


36


, not all the fluid is vaporized, particularly if the squeezing is strong, or rapidly repeated before vaporization occurs. This excess fluid overflows the tube


40


, runs down the outside of the tube


40


to the bottom of an annular catch well


90


between the tubes


50


and


40


. This liquid, if allowed to build up, would rob heat from the metal tube


40


. A drainage hole


60


at the bottom of the well


90


allows the excess fluid to drain into a separate tank


62


. Another drain line


63


empties condensate from the smoke chamber


14


to the tank


62


. The liquid collected in the tank


62


can then be removed through an access hole


64


and rubber stopper


66


.





FIG. 5

shows another alternative, presently preferred, embodiment of the smoke generator


30


′ (like parts in the FIG.


4


and

FIG. 5

embodiments being identified with the same part number, but distinguished by a prime). A key feature of the generator


30


′ is a spacer


92


disposed in the annular gap


43


between the glass envelope


42


′ of the electrical resistance heater


38


′ and the surrounding metal tube


40


. The spacer


92


is shown in its presently preferred form, that is, as a wire that is spiral-wrapped around the glass envelope


42


′.




The wire


92


is formed of any suitable non-corrosive material. Stainless steel is preferred. The wire


92


has a diameter that radially fills a significant portion (e.g. about 25 to about 75%) of the gap


43


. The exact width can vary, but the functional result is that the wire


92


maintains a generally uniform spacing circumferentially across the gap


43


without plugging or significantly impeding the flow of the liquid


34


to the region adjacent the heater. The spiral wrap of the wire


92


ensures that this radial spacing is also maintained axially (in the direction of arrow


93


).




The spacer wire


92


also creates a helical flow path


94


for the fluid


34


that is forced by fluid pressure (applied via the bulb


36


and air delivery tube


56


) upwardly through the gap


43


where the electrical resistance coil


44


vaporizes it. The helical flow path is longer than a linear path straight up the gap


43


, and thus increases the surface area, and interaction time, for the transfer of heat from the coil


44


, through the glass envelope


42


′, to the fluid. This increased surface area effect is reflected in the characterization of the spacer wire


92


also as a “wetting” wire.




The circumferentially even radial spacing, and this increased flow path and the resultant surface area for heat transfer, produces a greatly increased efficiency of operation as compared to the generator


40


described with reference to

FIGS. 2-4

. Turbulence produced by the presence of the wire


92


in the gap


43


is also believed to assist the heat transfer. In operation, with other factors the same, the generator


40


′ using the spacer and wetting wire


92


produces roughly twice as much smoke, evaluated by subjective visual comparison, than a generator


40


.




The generator


40


′ also secures the wire


92


in a selected axial location with respect to the heating coil


44


. The wire


92


is anchored principally by bending its upper end over the upper edge of the metal tube


40


, directing it down the outside of the tube


40


, and then clamping it under an O-ring


96


(which may be the O-ring shown in

FIG. 4

as sealing the tube


40


within the upper wall of the tank


32


). The O-ring


96


is readily replaceable to facilitate disassembly for repair or maintenance. However, any equivalent such as an adhering, clamping under a screw, or simply wrapping around a post or other projection, can work. The wire


97


is also preferably secured at its lower end


92




b


. As shown, a simple wrapping of the end


92




b


around the lower heater coil lead wire is a simple and effective lower anchor for the wetting wire


92


. However, many other known mechanical securing arrangements can be used.




The wire


92


is held by this mounting in an axial position such that the spiral turns are co-extensive with the heating coil


44


, and preferably extend below it to the bottom end of the glass envelope


42


′. In generators used in toys, the wire


92


has between 2 and 36 turns to provide a reliable, uniform spacing around and along the gap


43


, while increasing the path length by creating a helical flow path. For a generator with the illustrative dimensions given above, and a 0.001 to 0.005 inch gap clearance, the wire


32


preferably has a diameter of 0.001 to 0.004 inch. With a 0.004 inch radial-measure gap, the wire has a preferred diameter of 0.002 inch (50%), and 12 to 14 turns over the approximately one-inch axial length of the turns. The slight clearance between the wrapped wire and the adjacent surfaces permits a sliding insertion of the wire wrapped on the glass envelope


42


′ into the tube


40


, while still adequately controlling the mutual spacing of those components and creating the extended spiral flow path after the wire “relaxes” into the gap


43


.




In manufacture, the lower end


92




b


of the wire


92


is first wrapped on the lead wire


49


as shown. The lead wires


46


and


49


are centered in, and adhered within, plugs


98




a


,


98




b


that seal the ends of the glass envelope. The plugs are preferably a suitable high-temperature epoxy such as the product sold by Duralco under the trade designation “4525”. The plugs each extend into the cylindrical glass envelope


42


′ about ⅛ to {fraction (3/16)} inch to ensure a reliable seal.




The wire


92


, once anchored at its lower end, is wrapped over the outside of the envelope


42


. When the wrapped heater


38


′ is slid into position within the tube


40


, the upper end


92




a


is then directed down the outside of the tube


40


and secured by the O-ring


96


.





FIG. 2

shows the heat generator


30


installed in a toy gun


10


, in this case, a pistol styled like a fanciful “ray gun”. The body


16


of this gun includes a hollow casing of plastic or other suitable material. The gun body


16


is preferably molded from a suitable plastic in two mirror-image halves with the hand grip


20


and battery compartment


28


. The smoke chamber


14


can be formed integrally therewith, but preferably is molded separately and then secured to the front end of the gun body


16


(e.g., with a snap-on action) after the two halves are mated in clam-shell fashion. Rearward depression of the trigger


22


operates to engage an axially extending actuator (or “striker”)


68


through a pivoted, spring-loaded dog


70


, causing a like rearward movement of the actuator from a forward position adjacent the diaphragm


74


to an extreme rear position against the action of a coiled compression spring


80


. The dog


70


is mounted in a recess


68




r


formed in the lower side of the actuator


68


. At the rear limit position, a corner


72


of the body


16


cams the dog


70


to pivot against its spring


71


until it releases from the trigger


22


. This release allows the actuator to slide forward propelled by the compressed spring


80


to strike an elastic diaphragm


74


. It also defines the rear limit position of the movement of the actuator


68


.




With reference to

FIG. 2

, the smoke chamber


14


is defined by the diaphragm


74


(forming a generally planar rear wall


14




b


), a front wall


14




a


in generally parallel, spaced relation with the rear wall, and a generally cylindrical side wall


14




c


extending between walls


14




a


and


14




b


. The diaphragm


74


is preferably replaceably sandwiched between the smoke chamber


14


and the gun body


16


, and it can be mounted in a separate circular frame


76


that is so secured. A generally circular orifice


14




d


is formed in the front wall as an exit port for the smoke rings


12


. The orifice


14




d


is preferably positioned coaxially with the diaphragm


74


. In the preferred form shown for a hand-held toy gun


10


, the diameter of the orifice is in the range of about 1 to 3 inches, with about 1.25 inches being generally preferred.




The upper outlet end of tube


50


of the smoke generator


30


passes through a lower portion of the chamber side wall


14




c


to feed smoke produced by the generator


30


to the smoke chamber. (The generator


30


′ is preferably used.) An optional light


78


is attached inside the chamber wall


14




c


to facilitate visual inspection of the smoke in the chamber


14


and, in particular embodiments, to add illumination to the smoke inside the smoke chamber and/or to the rings eminating from it, particularly in darkened rooms. The chamber


40


can be made (whole or in part) from a transparent or translucent material such as a suitable plastic, such as polypropylene.




The ratio of the diameter of the orifice


14




d


to the internal diameter of the smoke chamber


14


is adjustable to maximize smoke ring quality and output by holding smoke in the chamber after it is produced, and then producing a well formed ring after the gun is “fired”. Typically, that ratio is as low as about 1:4, but preferably in a range of about 1:2 to 2:3. By way of illustration, but not of limitation, the orifice


14




d


, as noted above, has a diameter of about 1.25 inches, and the internal diameter of the smoke chamber


40


is about 2.5 inches. The chamber diameter ranges from 2 to 5 inches for the preferred gun


10


shown in

FIGS. 2 and 3

.




The gun is “fired” to eject at least one smoke ring by the actuator


68


striking the diaphragm


74


. The actuator in the preferred form illustrated is mounted in the body


16


at at least two axially separate bearing surfaces


16




a


and


16




b


. The actuator


68


reciprocates freely along its lengthwise axis in the direction of the axial arrow


18


. As shown in

FIGS. 2 and 3

, the actuator is approaching its forward position where the actuator head


82


strikes the diaphragm


74


. The resilience of the diaphragm material (and ribs


74




a


) returns the diaphragm to its original shape and returns the actuator


68


to a point where the trigger


22


when in its forward or unsprung position can engage the dog


70


and the gun can be fired again. There is no limiting forward position to the actuator other than the diaphragm. If the actuator stopped abruptly (or snaps) at a limit position, it is found that the ensuing pressure wave is not conducive to well-formed smoke rings. In the preferred form, the actuator is also generally centered on the diaphragm


74


and the orifice


14




d


. The coil spring


80


held in a cavity


16




c


formed at the center rear of the gun body urges the actuator forward, toward the diaphragm. The spring, when compressed, provides a motive force that propels the actuator to strike the diaphragm with its head


82


to deflect the diaphragm forwardly to thereby produce a pressure wave in the fluid in the smoke chamber


14


. In the preferred form shown, the spring


80


is captured at its front end on an end boss


68




a


of the actuator, and at its rear end the spring


80


abuts an adjustable stop member


84


. The stop


84


pivots freely about a pivot pin


84




a


in response to a manual movement of projecting lever


84




b


. The pivot is not centered in the main body


84




c


of the stop


84


so that rotation (in the clockwise direction as shown) produces a camming action that compresses the spring


80


. The force of the spring


80


on the stop, and friction with the pin


84




a


and the surrounding body


16


, secures it against further rotation once it is manually set. This manual rotation of the stop allows a convenient adjustment of the actuator striking force, and thereby the speed of the smoke rings ejected by the gun


10


when it is fired.




The actuator head


82


is preferably circular with a diameter near in size to that of the orifice


14




d


. The striking face


82




a


is preferably flat. The impact of the face


82




a


on the diaphragm


74


deflects the diaphragm forward a short distance, one sufficient to create a pressure wave within the smoke chamber that in turn creates a smoke ring that ejects from the gun


10


and travels forward, in an axial direction with respect to the gun. The quality, speed and number of smoke rings created depends on an interplay of factors such as the material, thickness, tension and mounting of the diaphragm, the rigidity of the striking face


82




a


, the mass and velocity of the actuator, and the absolute and relative sizes of the areas of the diaphragm and the striking face that interreact. In one form, as illustrated and as noted above, the diaphragm is an edge-mounted piece of latex rubber about 10 mils thick held so that it is flat before it is struck, but not stretched to any significant degree. If the diaphragm is tensioned, the actuator impact can produce a bouncing leading to the formation of multiple surges per firing (which may be desirable under certain circumstances). However, to produce a quality traveling ring with one impact, and use a taut diaphragm, the actuator head


82




a


preferably mounts a layer of foam rubber or like energy absorbing or “lossy” material to cushion the blow.




While the preferred embodiment uses an elastic diaphragm, it will be recognized that there are many ways to move a member to produce a wavefront in an adjacent fluid. For example, a rigid or resilient member can be mounted to move in the manner of a piston within a cylinder (e.g., the smoke chamber side wall), or the diaphragm can be coupled to a solenoid in the manner of a diaphragm in a telephone or loudspeaker, or a diaphragm can itself be formed of materials, or layers of materials, that deform in response, e.g., to applied voltages in manner that produces the desired pressure wave. These variations are intended to fall within the scope of the appended claims.




It is also contemplated, and it is presently preferred, to use an elastic diaphragm


74


′ that is bowed or curved slightly in cross section, e.g., ⅛ to ¼ inch measured at the center at a maximum. The direction of this curvature is convex with respect to the actuator head


82


(shown in dashed lines in FIG.


2


.). To restore this curved shape after being impacted by the actuator and driven toward a flat or concave configuration, a set of radial ribs


74




a


mutually-spaced may be formed integrally in the diaphragm material.




Similarly, while the actuator is described as a spring-loaded, linearly reciprocating “plunger”, an equivalent striking member can be formed in a wide variety of ways well known to those skilled in the art. Some examples are pivoting strikers (using a hammer-like pivoting action), solenoid-driven, pneumatically, and hydraulically-driven strikers, as well as direct drives for a rigid, piston-like diaphragm or diaphragm mountings.




In the preferred, hand-gun form illustrated herein, the tube


40


is preferably made from a metal or alloy thereof such as stainless steel. The envelope


42


,


42


′ of the heater, made from a high temperature silicate such as borosilicate glass, extends vertically so that its bottom end is above the top of the liquid


24


in the tank


32


, and its upper end extends above the upper end of the metal tube


40


. The metal tube


40


for a hand-gun


10


has an outer diameter of preferably 0.05 to about 0.07 inch, more preferably about 0.0546 to about 0.066 inch. Typically, the glass tube


42


preferably has an outer diameter of between about 0.049 to 0.055 inch, more preferably about 0.049 inch. A preferred radial spacing of the glass tube


42


to the inner wall of the tube


40


is between from about 0.001 to about 0.005 inch, preferably about 0.004 inch. This spacing has been found to promote the pumped movement of a suitable volume of liquid


34


to a region adjacent the heater in response to a pressure increase that can be produced manually, but not so much liquid that it strongly gushes up and out of the tube


40


, or requires a significant time delay for vaporization. In the preferred form, the heater reaches its operating temperature in about 5 seconds, and smoke can then be made repeatedly, on demand, in about ½ second.




By way of illustration, but not of limitation, when used in a toy smoke ring gun as shown in

FIGS. 1-4

, or a like application, the generator


40


′ is formed of a metal tube that is about 1.9 inches long, and a glass envelope about 1.5 inches long that extends above the tube


40


by about ⅜ inch. The heating coil


44


is about ¾ inch in axial length, terminating at its top end near the upper end of the tube


40


, as shown. The glass envelope has an outside diameter of about 0.049 inch and the average radial width of the gap


43


is, as noted above, about 0.004 inch. The wetting wire


92


is a 0.002-inch diameter stainless steel wire wrapped with 12 to 14 turns per inch.




The invention is compatible with a wide range of suitable smoke precursor liquids. However as discussed, it is an object of this invention to provide smoke that is essentially safe for use in settings in which humans are present. Preferably, that smoke is made from liquid that is approved by the U.S. Food and Drug Administration (FDA). A preferred liquid is water having a smoke producing amount of propylene glycol and less than about 5 ppm mineral impurities. Such liquid can be obtained from a variety of commercial sources including “Fog fluid FJ1Q, unscented” from Visual Effects Inc. of Bronx, N.Y. (USA).




The resistance coil


44


has a resistance of from between about 4 ohms to about 10 ohms when cold (room temperature), and draws about 400 to about 600 milliamps in normal use to produce smoke. In the absence of liquid, the coil heat continues to draw current, but its resistance increases without the liquid acting as a heat sink. In this “liquid-withdrawn” state, it draws preferably about 300 to 450 milliamps, a conservation of about ⅓ of the current drawn when vaporizing (assuming a fixed voltage). The resistance coil can be made from a wide range of suitable materials, but nickel or alloys of nickel are preferred. Nickel that is at least about 99.9% pure is preferred for use in the hand-gun


10


shown in FIG.


2


. The preferred coil has an outer diameter (O.D.) of about 0.02 inch.




A user of the toy gun


10


closes an electrical switch


86


to power the resistance coil


44


and energize the light


78


. Power can be supplied by any suitable means including the batteries


24


, or a cord extension to a household electrical socket or transformer. In the preferred toy gun embodiment using batteries for maximum portability, a battery compartment in the base


28


houses 6 AA batteries in series to provide about 9.0 volts with fresh batteries. After use, the voltage drops to about 7.5 volts, and after about 3 hours of use, to about 6.0 volts.




A second “trigger”


88


mounted in the hand grip


20


, when depressed against a spring force by the user, contacts and compresses the bulb


36


to increase fluid pressure in the tank


32


. This spring force acting on the trigger


88


is preferably provided by the resiliency of the bulb


36


itself. This increase in fluid pressure causes a rise in level of the liquid


34


into the annular space


43


between the heater and the tube


40


, toward the resistance coil


44


. The small volume of liquid in this narrow annular space


43


vaporizes very quickly (about ½ second) to produce smoke. That smoke rises into and fills the smoke chamber


14


. If the trigger


88


is pulled too strongly, or too often, the pumped liquid can overflow the tube


40


. If so, it runs into the well


90


at the bottom of the annular space between the tubes


40


and


50


where it is drained away so that it does not interfere with the vaporization process. Release of the trigger


88


lowers the fluid pressure as the resilient bulb


36


expands back toward its pre-compressed configuration. This decrease from the increased fluid pressure level immediately causes the liquid


34


to withdraw from the space


43


adjacent the heater


38


. Smoke generation then, in most cases, ceases promptly.




The toy gun thus has a readily available supply of liquid


34


in tank


32


, for repeated fast production of batches of smoke “on demand”. Of course, the smoke generator


30


can be operated continuously or semi-continuously, not “on-demand”. However, continuous or semi-continuous operation requires a greater power and liquid usage, and a likely waste of smoke that is produced, fills the chamber


14


, and flows, unstructured, out of the orifice


14




d


, not as rings. As discussed above, the toy gun


10


can operate generally independently of orientation so that smoke rings can be produced with, e.g., a sideway or even upside down orientation, or the gun can be placed on its side when not in use. As also discussed above, the smoke generator


30


,


30


′ and gun


10


of the present invention can operate with water-based smoke precursor liquids (usually water with polyglycol, or the like, and a low level of mineral impurities). Smoke formed from such liquids are less likely to be irritating, or to have other health hazards, than known oil-based; liquids. It will also be appreciated that the spacer and wetting wire


92


is a simple and low cost enhancement to the efficiency and volume production of fog as compared to a like generator with a “straight-through” flow path and no arrangement to establish and maintain a uniform spacing around the heater.




Although the invention has been shown and described with respect to its preferred embodiments, it will be appreciated from the foregoing that various other changes, omissions and additions will occur to those skilled in the art without departing from the spirit and scope of the invention.




For example, while the invention has been described with respect to an air-filled, deformable bulb as a source of a variable pressure acting as the liquid


34


in the tank


32


, a wide variety of other arrangements can achieve the same end effect. The liquid can be held in a deformable tank. A piston and cylinder arrangement can vary the pressure hydraulically. A compressed air supply or gas from a CO


2


cartridge can be applied to the tank. Further, while the heater has been described as an electrical resistance wire in a glass envelope, a wide variety of resistance and other heaters are known that can be adapted to vaporize the liquid, whether continuously or on demand. Further, while a hand gun is described as the preferred application of the present invention, it will be recognized that the invention can be readily adapted to other toys (toy rifles, bazookas, and cannons, and model trains and boats) and to other smoke applications (theatrical productions).




While the spacer


92


has been described as a spiral-wrapped wire, it can assume other forms, e.g. projections from the tube


40


or the envelope


42


′, or separate annular rings or axial ribs or wires or arrays of ribs or wires, or blocks of solid materials adhered or secured to set the gap spacing. Likewise, the enhanced “wetting” function produced by the spiral wrap and its resultant spiral path can be created by a wide variety of structures that direct the fluid flow in a path that is increased as compared to a generally linear axial flow along the gap


43


. The wire


92


can have a non-circular cross-section. And as noted above, a variety of mechanical arrangements can secure the wetting wire, or equivalent components, in position, whether permanently or replaceably.




These and other modifications and variations disclosed herein are intended to fall within the scope of the appended claims.



Claims
  • 1. A smoke generator comprising:a) a supply tank that holds a liquid, b) a source of variable fluid pressure in sealed fluid communication with the supply tank for increasing and decreasing fluid pressure in the tank to feed the liquid to and from a heating unit; c) a first tube with a first end entering into the supply tank, and a second smoke outlet end; d) a heater positioned at least partially within the first tube for vaporizing the pressurized liquid driven by an increase in the pressure into a narrow annular region between the heating element and the surrounding tube; and e. a spacer that maintains a generally uniform circumferential spacing between said heater and said first tube along the length of said heater, wherein said spacer is disposed in said narrow annular region and is constructed to allow a flow of said liquid and its vapor through said spacer and said narrow annular region and to increase the flow path length of said liquid and its vapor as it is driven from said tube to said narrow annular region.
  • 2. The smoke generator of claim 1 wherein said spacer is a spiral-shaped wire.
  • 3. The smoke generator of claim 2 wherein said wire has a diameter that is in the range of about 25% to about 75% of said generally uniform spacing.
  • 4. The smoke generator of claim 3 wherein said wire has between two to thirty-six turns per inch.
  • 5. The smoke generator of claim 4 wherein said wire has a diameter of about 0.002 inch and twelve to fourteen turns per inch.
  • 6. The smoke generator of claim 2 further comprising a mechanical anchor that secures the axial position of said wire to a point that is generally coextensive with said heater.
  • 7. The smoke generator of claim 6 wherein said mechanical anchor includes an upper end of said wire that is directed down the outer surface of said first tube and a clamp that secures said upper end.
  • 8. A smoke generator comprising:a) a tank holding a supply of a liquid that can be vaporized to produce the smoke, b) a first tube that has a first end in fluid communication with the fluid in said tank and extending generally upwardly from said tank, c) a heater disposed in said first tube above said liquid in said tank, d) a spacer that maintains a generally uniform circumferential spacing between said heater and said first tube along the length of said heater, and e) a variable fluid pressure source generally connected to the tank operable to force the said liquid from said tank into said heater-to-tube space in response to an increase in the pressure produced by said variable fluid pressure source from a first level, and evacuate the fluid from said heater-to-tube space in response to a decrease in said pressure from said increased level, said heater vaporizing the portion of said liquid driven by said pressure increase into said heater-to-tube space to produce the smoke, and said spacer being disposed in said narrow annular region and constructed to allow a flow of said liquid and its vapor through said spacer and said narrow annular region and to increase the flow path length of said liquid and its vapor as it is driven from said tube to said narrow annular region.
  • 9. The smoke generator of claim 8, further comprising mechanical means operative in said circumferential spacing to increase the length of the flow path of said fluid through said heater-to-tube space as compared to a linear axial flow.
  • 10. The smoke generator of claim 9 wherein said spacer and said mechanical means comprise a spiral-wrapped wire disposed in said heater-to-tube space.
  • 11. The smoke generator of claim 8, 9, or 10, wherein the variable pressure source is a flexible bulb in sealed fluid connection to the supply tank.
  • 12. The smoke generator of claim 8, 9, or 10, wherein the heater comprises an electrical resistance heater sealed in a heat-conductive envelope.
  • 13. The smoke generator of claim 12, wherein at least the side wall of said heat-conductive envelope is glass.
  • 14. The smoke generator of claim 12, wherein the radial dimension of said circumferential space is in the range of about 0.001 to about 0.005 inch.
  • 15. The smoke generator of claim 8, 9 or 10, wherein said first tube is formed of a metal, and it forms part of an electrical connection to the electrical resistance heater.
  • 16. The smoke generator of claim 15, wherein the metal is stainless steel.
  • 17. The smoke generator of claim 8, 9 or 10 further comprising a second tube that is disposed generally concentrically around said first tube and defining a liquid catch well therebetween.
  • 18. The smoke generator of claim 17, wherein said second tube is formed of a metal, and it forms part of an electrical connection to the electrical resistance coil.
  • 19. A toy smoke-ring gun, comprising:a body extending generally in an axial direction, a smoke chamber at a front end of said body, said smoke chamber having front, rear and side walls and an outlet orifice formed in a front end wall for forming smoke rings that travel axially, an axially displaceable member forming at least part of said rear end wall that is generally parallel to, and spaced from, said front end wall, a smoke generator whose outlet is in fluid communication with said smoke chamber, said smoke generator including a heater, a supply of a smoke-producing liquid in a tank, and a pressurizer acting on said liquid supply to produce on-demand smoke to said smoke chamber, a first tube extending into said liquid supply at a lower end and surrounding said heater over a region above said tank, a spacer to establish a generally uniform circumferential spacing between said heater and said first tube, and an actuator mounted on the body and operable to move the displaceable member to produce a wave pressure inside the smoke chamber that causes a traveling smoke ring to be formed as a portion of the smoke held in the smoke chamber is ejected through said orifice, wherein said spacer is disposed in said narrow annular region and is constructed to allow a flow of said liquid and its vapor through said spacer and said narrow annular region and to increase the flow path length of said liquid and its vapor as it is driven from said tube to said narrow annular region.
  • 20. The toy smoke-ring gun of claim 19 further comprising mechanical means operative in said circumferential spacing to increase the length of the flow path of said fluid through said heater-to-tube space as compared to a linear axial flow.
  • 21. The toy smoke-ring gun of claim 20 wherein said spacer and said mechanical means comprise a spiral-wrapped wire disposed in said heater-to-tube space.
  • 22. The toy gun of claim 19, 20 or 21, wherein said pressurizer comprises an air-filled bulb in sealed fluid communication with said smoke-generating liquid in said tank.
  • 23. The toy gun of claim 22, wherein the heater is in the first tube to vaporize the smoke, producing fluid when said pressurizer is activated to produce an increased pressure level in such tank that drives said liquid upwardly into said first tube.
  • 24. The toy gun of claim 23, wherein the heating element further comprises an electrical resistance heating coil, and further comprising a battery powering said heater coil and a switch connected therebetween to control the activation of said coil.
  • 25. The toy gun of claim 24, wherein said coil draws a current of between from about 400 to 600 milliamperes with said liquid adjacent said heater within said first tube, and draws less current, due to an increased resistance when said liquid is withdrawn from said first tube, in response to a decrease in the fluid pressure provided by said pressurizer.
  • 26. The toy gun of claim 25, further comprising a sealed vessel that encloses said resistance coil and wires extending through said vessel to connect electrically said coil to said battery and support it in a spaced relationship with respect to said vessel.
  • 27. The toy gun of claim 26, wherein the vessel consists of a glass.
  • 28. The toy gun of claim 27 wherein the radial spacing between the glass vessel and said first tube is between from about 0.001 to about 0.005 inches.
  • 29. The toy gun of claim 28, wherein the first tube is formed of a metal.
  • 30. The toy gun of claim 19, 20 or 21 wherein the smoke generator further comprises a second metal tube coaxial with and surrounding said first tube and defining a catch well for said liquid therebetween.
  • 31. The toy gun of claim 19, 20 or 21 wherein said axially displaceable member comprises a diaphragm of an elastic material.
  • 32. The toy gun of claim 31 wherein said diaphragm is generally circular and edge-mounted to form at least a portion of said rear wall.
  • 33. The toy gun of claim 32 wherein said diaphragm is formed of rubber.
  • 34. The toy gun of claim 32 wherein said diaphragm is generally coaxial with said orifice and said actuator is movable to strike said diaphragm to produce said pressure wave.
  • 35. The toy gun of claim 34 wherein said diaphragm has a low tension and said actuator is rigid.
  • 36. The toy gun of claim 31 wherein said actuator is a member that is linearly slidable within said body and further comprising a spring captured between a rear end of said member and said body.
CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. application Ser. No. 09/732,508 filed on Dec. 7, 2000 now U.S. Pat. No. 6,421,502.

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Entry
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Continuation in Parts (1)
Number Date Country
Parent 09/732508 Dec 2000 US
Child 10/127708 US