US 3597140 A
Description (OCR text may contain errors)
United States Patent Peter Rabe Muhlheim am Main, Germany 840,350
July 9, 1969 Aug. 3, i971 Heinrich Malner Gmbli Offenbach am Main, Germany July 17, 1968 Germany inventor Appl. No. Filed Patented Assignee Priority GAS LIGHTER 7 Claims, 9 Drawing Figs.
US. Cl. Int. Cl. Field 0! Search 431/131 rza z/os 431/129- -131, 206. 207. 254. 255,344
References Cited UNITED STATES PATENTS 2.620.643 l2ll952 Nissen 5/1955 9/l956 5/l958 6/1959 8/l96l 9/l964 5/l965 Nissen Gruber Zellweger.
Weiss Court Yoshino Primary Examiner- Edward J. Michael Attorney-Michael S. Striker ABSTRACT: A fuel tank burner unit has an inlet an to receive fuel from the t fuel issuing in gaseous burner unit is heated by is interposed between and the inlet to receive to supply it to the inlet defines a plurality of least in part bounde which is in heat-exch contains liquified gaseous fuel. A d an outlet, the inlet being arranged ank. igniting means serves to ignite state from the outlet whereby the the resulting flame. Vaporizing means and communicates with the fuel tank from the former fuel in liquid state and in gaseous state. The vaporizing means elongated fuel paths each of which is at d by an inner heat-exchanging surface anging relationship with the burner unit.
Patented Aug. 3, 1971 3 Sheets-Sheet 5 GAS LIGHTER BACKGROUND OF THE INVENTION The present invention relates to pyrophoric lighters, and more particularly to gas lighters.
Gas lighters fall, generally speaking, into two categories. One category of gas lighter supplies the burner unit of the lighter directly from the gaseous phase of the liquefied gas in the fuel tank. The other type of gas lighter supplies the burner unit with fuel directly from the liquid phase. The present invention is concerned with the latter type.
This latter type of gas lighter has the advantage, as compared to the former type, that no such filler materials as felt or the like need be accommodated in the interior of the tank, thereby eliminating the well known disadvantages associated with the use of these filler materials. On the other hand, however, these so-called liquid-gas lighters" suffer from certain problems oftheir own. The heat of vaporization ofliquid gas is approximately 100 cal/g. C, and the specific heat of liquid gas is only 0.6 cal/g. C. From this it follows that when vaporization of the liquid gas takes place in the interior of the burner unit in the vaporization zone provided for this purpose, the surrounding areas are drastically cooled during the vaporization unless the liquid gas supplied to the vaporization is relatively warm. As a result of this problem small temperature differences between the boiling temperature and the tempera ture of the liquid gas, and high setting of the flame, result in the problems which are known with respect of this type of lighter to those skilled in the art. This is particularly noticeable if the ambient temperature is relatively low, for instance in winter or generally in cold climates.
Among the known prior art constructions of liquid-gas lighters are some wherein a porous sinter body of synthetic plastic material, ceramic or metal is arranged at the inlet of the burner unit, that is where the burner unit receives fuel from the fuel tank, and is intended to serve both for throttling the fuel flow as well as effecting vaporization of the fuel. Because the throttling effect depends entirely upon the location in the sintered body at which the vaporization takes place, and because this location changes in dependence upon a host of influences, particularly the prevailing temperature, this leads to a very uneven supply of fuel to the burner outlet and, accordingly, to an uneven flame. Aside from this there is, of course, the disadvantage that it is difficult in these construe tions to adjust the throttling effect if this is desired.
Other lighter constructions of the type under discussion utilize separate throttling devices and vaporizing devices. In one such construction there is an insert provided in the fuel tank which extends close to the bottom of the latter and which carries at the top a throttling device in form ofa needle valve, and below the throttling device a porous sinter body of synthetic plastic material or metallic oxide as vaporizing device. The porous sinter body is completely enclosed in the insert and its surface is exposed only at its underside and at a small portion of its upper side. It has been found that at low temperatures this construction will not operate properly. The reason for this is that the heat necessary for vaporization of the fuel is withdrawn from the liquid fuel and from the ambient region, with the result that a temperature drop of between 5 and C. occurs in the vaporizing device. Because ordinary butane develops a vapor pressure of 1 atm. at -O,S C., vaporization stops under these circumstances or droplets of liquid issue from the burner and vaporize as soon as the ambient temperature is between 4.59.5 C. Attempts have been made to counter this by providing the butane with additives in form of isobutane and propane; this, however, leads to an increasing separation of the contents of the fuel tank into their components and to progressively greater unsteadincss of the flame.
In another prior art construction the throttling device is constituted by a compressible annular area of a wick or the like and the vaporization is intended to occur at the surface of the less strongly compressed wick portions located within the compressible annular area. Again, however, vaporization will not properly take place at low temperatures because under these circumstances the vaporizing body in effect freezes" within the annular compressible area. To overcome the lastmentioned problems still another construction is known wherein a throttling device is provided in form of a compressible porous annular body, and downstream thereof there is arranged a vaporizing device in form of an annular gap provided in suitable manner and limited or delineated by metallic surfaces which are in heat-exchanging contact with the upper side of the burner unit where the flame develops. One surface bounding the gap is profiled, for instance provided with a thread. Tests have shown that this construction is usable only if the size of the flame is held very small, and in fact to limits which are not practically feasible. If the flame is adjusted to be larger, it becomes very uneven, being subject to puffing and jumping, apparently as a result of large gas bubbles which develop in the gap and which forcibly eject droplets of liquid fuel.
SUMMARY OF THE INVENTION It is a general object of the present invention to overcome the aforementioned disadvantages.
More particularly, it is an object of the present invention to provide a gas lighter of the type under discussion which is not possessed of these disadvantages.
A concomitant object of the invention is to provide such a gas lighter which will operate reliably and without difficulties even at low ambient temperatures.
A further object of the invention is to provide such a gas lighter which will provide a uniform constant flame under all operating conditions.
In pursuance of the above objects, and others which will become apparent hereafter, one feature of my invention resides in a gas lighter which, briefly stated, comprises a fuel tank for liquefied gaseous fuel and a burner unit having an inlet and an outlet. Igniting means is operative for igniting fuel issuing in gaseous state from the outlet whereby heat from the resulting flame raises the temperature of the burner unit. Vaporizing means is interposed between and communicates with the fuel tank and the inlet for receiving fuel in liquid state from the former and for supplying it in gaseous state to the latter. The vaporizing means comprises a plurality of elongated fuel paths for movement of the fuel from the fuel tank to the inlet, and each of the fuel paths is bounded at least in part by an inner heat-exchanging surface which is in heat-exchanging relationship with the burner unit.
With my novel lighter construction the heat-exchanging surfaces supply the vaporizing liquid gas with enough heat from the heated portion of the burner unit that the temperature drop which occurs on vaporization is scarcely noticeable. Despite this the flame of my novel lighter will be steady and will not be made unsteady by issuing gas bubbles. I wish it to be understood that the development of gas bubbles at the heat-exchanging surfaces is to be expected, but because such gas bubbles do not occur simultaneously in all of the many fuel paths provided, and instead of statistically distributed over the entirety of the fuel paths, they do not give rise to the objectionable problems mentioned earlier. Moreover, they are of exceedingly small volume when they do occur.
In accordance with a currently particularly advantageous appearing embodiment, the vaporizing device comprises at least one porous layer which completely extends across the cross-sectional area of the passage connecting the fuel tank with the inlet of the burner unit, and which consists of a material having good heat conductivity of at least 10 but preferably in excess of 50 kcal/m.h. C. It is this layer which defines the vaporizing zone and which makes possible adequate heat exchange in each of the fluid paths. The layer may be part of a porous vaporizing body, or the vaporizing body may consist entirely of the highly heat-conductive material.
It is most advantageous if the thermally or heat-conductive material is a metal, especially copper, having a thermal conductivity in excess of I kcal/m.h. C.
The thermally conductive material may be sintered to assume the desired configuration. It may, however, also be in form of a wire mesh having one or several layers. Evidently, the mesh will be very small, and wire-mesh materials suitable for this purpose are commercially available for filtering purposes. A further possibility is to produce a layer of good thermal conductivity by metallizing a porous body, that is by galvanically applying or spraying metallic material onto such a body.
It is of course essential that the vaporization takes place within the vaporizing body. To assure this the latter should have a flow resistance which is at least equal to percent of the flow resistance ofthe throttling device located upstream of the vaporizing body. It is particularly advantageous if the vaporizing body is in form of a substantially plate-shaped member because this results in the provision of a large number of parallel fluid paths of limited length so that the desired small flow resistance can be readily obtained. The thickness of such a plate depends upon the amount of heat available for transmission to the vaporizing body. Thus, if the burner portion which is subjected to heat from the flame is relatively large, and if within the burner unit there is relatively little resistance to thermal conduction, the thickness of the porous layer or plate can be quite small.
It is also advantageous in accordance with the invention that substantially the entire surface of the plate member at the outlet side thereof, that is at the side communicating with the inlet opening of inlet opening, be exposed. If this is the case, then all parallel paths may communicate with a gas-collection space directly adjoining this upper surface. It is to be noted, however, that this space should be as small as possible to assure that when the burner valve is closed, no significant quantities of fuel can accumulate in the space if the temperature drops below the dewpoint of the gas, because these would instantaneously expand when the valve is open.
It may be advantageous in certain circumstances to further increase the outlet surface of the porous body constituting the vaporizing body, in order to obtain as many outlets as possible from the parallel fluid paths. For this purpose the vaporizing body may be of conical configuration at its downstream end, that is at the outlet side.
The inlet side of the porous vaporizing body, that is the side facing towards the fuel tank, may be contacted over substantially its entire surface area with a yieldable porous material, such as filter paper. This assures that all parallel fuel paths are filled with liquid gaseous fuel and contribute to vaporization thereof. In fact, the throttling device located upstream or ahead of the vaporizing body may in its entirety consist of yieldable porous material which contacts the inlet side of the vaporizing body. The throttling device may, in accordance with the invention, be thermally insulated from the vaporizing body to assure that the temperature drop occuring as a result of the throttling action has no disadvantageous influence on the intended supply of heat to the vaporizing body.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construc tion and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic side-elevational view of a gas lighter embodying the present invention;
FIG. 2 is a fragmentary vertical section through a gas lighter of the type shown in FIG. 1, and embodying a first embodiment of the invention;
FIG. 3 is a view similar to FIG. I but embodying a vsecond embodiment of the invention;
FIG. 4 is a fragmentary detail view, in longitudinal section and on an enlarged scale, illustrating one embodiment of a vaporizing body according to the present invention;
FIG. 5 is a view similar to FIG. 4 but illustrating a further embodiment;
FIG. 6 is a view similar to FIG. 4 illustrating an additional embodiment;
FIG. 7 is a view similar to FIG. 4 illustrating yet another embodiment;
FIG. 8 is a view similar to FIG. 4 illustrating still a further embodiment; and
FIG. 9 is a view similar to FIG. 4 and illustrating yet an additional embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing firstly the diagrammatic illustration of FIG. 1 it will be seen that the lighter shown there comprises a fuel tank 1 surrounded at least in part by a metallic housing 2. An upper projection 3 carries a push bar 4 which, when it is depressed downwardly as seen in FIG. 1, causes the cap 5 to swivel about a horizontal axis and simultaneously turns a nonillustrated spark wheel which cooperates in known manner with a flint. Of course, other ignition means can also be provided. A burner unit 6 is threaded into the tank, as diagrammatically illustrated in FIG. 1, and a filling valve 7 is provided in the bottom of the tank 1 so that the latter may be filled with liquid gaseous fuel.
FIG. 2 shows one embodiment of the invention, with the burner unit being illustrated in its closed position in which no gas can issue. The arrow identified with reference numeral 8 in FIG. 2 indicates the closing force exerted by the cap 5 when the latter is in the position shown in FIG. 1. The cap 5 is not illustrated in FIG. 2 and its operation, as well as that of the pressure bar 4 are entirely conventional and well known to those skilled in the art.
The fuel tank 1 shown in FIG. 2 is provided with screw threads 9 into which there is threaded a housing 12 which is closed at its lower end by a bottom wall 11. An annular sealing member 10 is interposed between the upper ends of the housing 12 and the tank 1.
The housing 12 is provided in turn with a screw thread 13 into which there is threaded a throttle-setting member 14 provided at its upper opening with exterior teeth 15 with which corresponding teeth of a setting wheel 16 mesh which is pushed over the upper end of the member 14. An elastic disk 17 of suitable construction retains the wheel 16 in the illus trated position. It will be evident that turning of the wheel 16 in turn effects turning of the member 14.
A substantially tubular burner 18 is located in the interior of the member 14 and is shiftable axially in a telescopic member 20 against the force exerted by a spring 19. The member 20 bears upon a valve member 21 which in closure position is seated on a valve seat 22, as illustrated. A pressure spring 23 is provided which in known manner tends to lift the valve member 21 from the valve seat 22, that is to move it upwardly as seen in FIG. 2, in order to provide for quick and ready opening of the valve when the force 8 is relieved by opening of the cap 5. The operation of the burner, and of the valve just described, is well known.
Reference numeral 24 designates an insert on which the valve seat 22 is provided. The insert 24 is provided at its underside with a recess 25 wherein there is lodged a substantially plate-shaped porous vaporizing body 26 of a material having good thermal conductivity. The circumference of the body 6 is in thermally conductive contact with the insert 24.
FIG. 2 shows that the outlet surface 27 of the body 26, that is the one facing away from the interior of the fuel tank containing the liquefied gaseous fuel, is at least substantially unobstructed and juxtaposed with a slightly conical wall 28 of the insert 24, which wall leads to the centrally arranged outlet channel 29 closed by the valve 21, 22 when the latter is in the position shown in FIG. 2.
A sealing ring of elastomeric material or the like is identified with reference numeral 36 and sealingly abuts against the underside of the insert 24. Located within the center opening of the annular sealing ring 36, as well as interposed between the sealing ring 36 and the bottom wall 11, is a throttling body 30 which in the illustrated embodiment is composed of three sections 31, 32 and 33 which may be of differing porosity. The material of the body 30 may but need not be a porous elastomeric cross-linked polyurethane such as is available commercially under the trade name Zellvulkollan. An opening 34 is provided in the bottom wall 11 and a plug 35 of porous material abuts the underside of the bottom wall 11 and serves to supply liquid gas to the throttling body 30 from the gas supply contained in the tank (and not illustrated).
It will be appreciated that turning of the wheel 16 results in axial movement of the member 14 either upwardly or downwardly. If the movement is downwardly, then the sealing member 36 is axially and radially compressed, the radial compression being the result of radially inwardly directed escape of the material of the member 36. This, in consequence leads to corresponding compression of the throttling body 30 and thereby permits precise variation of the flow resistance offered by the body 30 and adjustment of the height of the flame which develops in the region of the arrow 8 in response to activation ofthe ignition means.
Lifting of the cap 5 in the direction opposite the arrow 8 permits the valve 21, 22 to open. The pressure difference between the interior and exterior of the tank 1 results in movement of liquid gas through the throttling body 30 into the vaporizing body 26. The vaporization taking place in the latter is aided by the supply of heat radiated by the flame onto the members 14 and 16 in the region of the arrow 8, and transmitted via the insert 24 to the thermally conductive vaporizing body 26. As soon as heat so transmitted has reached the body 26, and this occurs very quickly, gas issuing from the upper open end of the burner member 18 will produce a very steady flame even at low ambient temperature.
The embodiment illustrated in FIG. 3 differs from that of FIG. 2 only in some respects, and identical elements have been identified with identical reference numerals. In FIG. 3 the fuel tank 41 consists of synthetic plastic material, by contrast to the embodiment of FIG. 2. Similarly, the housing for the burner unit, identified with reference numeral 42, consists of synthetic plastic material; it is provided, as clearly shown, with an internal screw thread 43 and is formed of one piece with the fuel tank 41. The sealing member of FIG. 2 is therefore not necessary in the embodiment of FIG. 3.
The sealing member 36 is again provided as before and prevents escape of the fuel in such a manner as to circumvent the vale 21, 22. Because the tank 41 in FIG. 3 consists of synthetic plastic material, and because such material has low properties of thermal conductivity, the temperature decrease resulting from the throttling of the fuel in the throttling body 30 has almost no influence upon the vaporizing body 26 consisting of a material having good is conductive properties. This is further aided by the fact that the material of the sealing ring 36 and that of the throttling body 30 itself has poor heat conductivity.
The vaporizing body 26 is again heated-which term identified of course relative because the temperature differences involved are not particularly large--via the member 14 in the manner discussed earlier with respect to FIG. 2. Therefore, the vaporization taking place in the body 26 is not adversely affected by the throttling effect of the body 30. Conversely, the heat supplied to the body 26 does not, however, lead to premature vaporization of the fuel in the body 30 because the latter is thermally insulated from the member 14.
In FIGS. 4-9 I have illustrated in fragmentary sectional views several possible embodiments of the vaporizing body and the associated insert. Thus, FIG. 4 shows the insert identified with reference numeral 24 and provided at its underside, that is the side facing away from the vale 21. 22 in FIGS. 2 and 3, with a two-step recess 50. Located in the outermost portion of this recess is a plate-shaped porous vaporizing body 51 consisting of sintered copper. It abuts with its circumferential edge face and with a portion of its upper surface, that is the one facing towards the vale 21, 22, the metallic material of the insert 240 while the major portion of its upper surface is unobstructed and faces a gas space 52 which is constituted by the second step of the recess 50. Reference numeral 9 again identifies the conduit communicating with the valve 21, 22.
In the embodiment of FIG. 5 the insert is identified with reference numeral 24 and provided on its underside with a recess 53 which is not stepped by contrast to that in FIG. 4. Located in the recess 53 in FIG. 5 is a sintered vaporizing body 54 of substantial disk-shape which is provided at one or, as illustrated, at both axial end faces with circumferentially extending raised beads 55. This maintains the upper surface of the body 54 spaced from the bottom face of the recess 53 so as to define a gas space 56.
In the embodiment shown in FIG. 6 the insert 24c is provided at its underside with a substantially conical recess 61 bounded by an inner conical surface 62. Lodged in the recess 61 is a sintered vaporizing body 57 composed of a conical portion 59, an axial extension 60 which projects into the passage or conduit 29, and a radial flange extending from the base of the conical portion 59 and identified with reference numeral 58. The recess is slightly stepped, as illustrated, so that the flange 58 is retained in the step to position the body 57 in desired relationship in the recess 61. The gas space is identified in FIG. 6 with reference numeral 63 and is quite small as is evident.
In the embodiment of FIG. 7 the insert 24d is provided with a recess 64 which is not at all stepped and which receives a porous sintered body 65 whose opposite axial end faces are covered respectively with layers 66 and 67 of filter paper for the reasons and purposes discussed earlier in this specification.
The insert 24e shown in FIG. 8 is provided with a recess 68 similar to the recess 64 in FIG. 7. Here, however, the vaporizing body is composed of one or several layers of wire mesh of the type discussed earlier, and a layer 70 of filter paper cover ing the upper surface of the body 69.
Finally, the embodiment illustrated in FIG. 9 shows an insert 24fprovided with a recess 71 corresponding to the recess 68 in FIG. 8. Here, the vaporizing body is composed ofa layer 72 of filter paper whose upper surface is metallized, that is provided with a metal layer 73 which is applied in the manner discussed earlier. Evidently, the layer 73 must be porous.
According to the invention it is essential that in all embodiments the thermally conductive material which extends transversely to and across the flow direction of the gas through the vaporizing body, is in good thermally conductive relationship with the respective insert 24 etc., and through the same with the member 14 and thereby with the surfaces which are heated when a flame is generated. In many of the embodi ments this can be accomplished very simply by press-fitting the respective vaporizing body into the recess provided in the associated insert. However, and particularly if a wire-mesh material is involved as for instance in FIG. 8, the same may be formed into a cup shape, secured in the associated insert in the manner of a membrane, soldered, welded or otherwise mounted in good heat-exchanging contact with the associated insert. My invention is particularly advantageous in lighter constructions wherein the burner unit is mounted in a tank consisting of synthetic plastic material, such as for instance shown in FIG. 3. Because of the poor thermal conductivity of synthetic plastic material the disadvantages discussed in the introductory portion of the specification with reference to the prior art, relating to the incomplete vaporization of the fuel at low temperatures, are particularly prevalent under this circumstance. The invention thus makes it possible for the first time to construct a liquid-gas lighter which uses a fuel tank of synthetic plastic material and is nevertheless fully and reliably operational under all operating conditions.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.
While the invention has been illustrated and described as embodied in a gas lighter, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
l. A gas lighter, comprising a fuel tank for liquefied gaseous fuel; a burner unit having an inlet and an outlet; igniting means operative for igniting fuel issuing in gaseous state from said outlet, whereby heat from the resulting flame raises the temperature of said burner unit; vaporizing means interposed between and communicating with said fuel tank and said inlet for receiving fuel in liquid state from the former and supplying it in gaseous state to the latter, said vaporizing means comprising inner heat-exchanging surfaces in heat-exchanging relationship with said burner unit and each at least in part bounding an elongated fuel path for movement of said fuel from said fuel tank to said inlet; and throttling means for fuel in liquid state upstream of said vaporizing means intermediate the same and said fuel tank in heat-exchanging relationship with at least said heat-exchanging surfaces and having a thermal conductivity factor which is poorer than that of said heat-exchanging surfaces.
2. A gas lighter as defined in claim 1, said vaporizing means comprising wall means defining a conduit communicating with said fuel tank and said inlet, and insert means lodged in said conduit and defining said plurality of fuel paths.
3. A gas lighter as defined in claim 2, wherein said throttling means is thermally insulated from said insert means.
4. A gas lighter as defined in claim 2, said conduit having a predetermined cross-sectional area, and said insert means comprising at least one porous insert layer extending across said entire predetermined area and consisting at least in part of a material of high thermal conductivity.
5. A gas lighter as defined in claim 4 wherein said material is a wire-mesh material.
6. A gas lighter as defined in claim 2, said insert means comprising an insert member having a surface facing towards said fuel tank and provided with inlet apertures of the respective fuel paths; and further comprising a body of yieldable porous material upstream of said insert member in contact with said surface thereof and at least in part constituting said throttling means.
7. A gas lighter as defined in claim 2, said insert means comprising an insert member of substantially disk-shaped configuration.