Abstract:
A catalytic gas combustion device for an appliance for personal use with a gas supply device and a catalyst connected to the gas supply device is disclosed. To ignite the gas/air mixture and therefore to initiate catalytic combustion at the catalyst, an ignition device which can be controlled by an ignition system is provided. The gas supply device has a bypass for branching off part of a gas stream which flows onto the ignition device. In this way, the ignition system is actuated even shortly after the gas valve device is opened, and the catalyst is brought to its operating temperature as a result of the explosion of the gas/air mixture.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation application of PCT Application Number PCT/EP01/02769, filed Mar. 13, 2001, which claims priority, under 35 U.S.C. 119, from German Application Number 10027719.5, filed Jun. 3, 2000, hereby incorporated by reference in its entirety. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The invention relates to a catalytic gas combustion device for an appliance for personal use, in particular a hair shaping appliance, such as a hair curler or hair dryer.  
         BACKGROUND  
         [0003]    Catalytic gas combustion devices of this type are used in appliances for personal use which generate heat energy by means of gas without electrical current. An appliance of this type is sold, for example, by the applicant itself under the designation HS3 Plus as “Braun Style Shaper”. This hair shaping appliance includes a catalytic gas combustion device consisting of a piezoelectric igniter with two ignition electrodes arranged next to one another. These ignition electrodes are arranged in the chamber surrounding the catalyst.  
           [0004]    To operate the appliance, the gas supply initially is opened mechanically via a valve device on the gas supply device. Gas flows through the gas supply device, mixing with air, and then passes into the catalyst space. The catalyst includes a tubular screen part, and the gas/air mixture also passes into the chamber, where it is flows around the ignition electrodes. The piezoelectric igniter is then ignited by hand, and sparks jump from one electrode to the other, causing the gas/air mixture in the chamber to ignite and thus initiate catalytic combustion at the catalyst. A certain amount of time elapses before the gas/air mixture reaches the electrodes, and only then is it possible to ignite the gas/air mixture.  
           [0005]    The object of the invention is to provide a catalytic gas combustion device for an appliance for domestic use, in particular a gas curler or hair dryer, in which the ignition of the gas/air mixture can be induced shortly after the opening of the gas supply, even simply by the initiation of the ignition operation, so that catalytic combustion commences quickly.  
         SUMMARY  
         [0006]    The invention relates to a catalytic gas combustion device including a bypass. The bypass allows part of the main gas stream to be branched off and supplied to the ignition electrode to cause the combustion of the gas by the actuation of the ignition device after a very short time. As a result, the gas located in the catalyst space and surrounding the catalyst bums abruptly and the catalyst thus reaches its operating temperature, which is necessary for satisfactory catalytic combustion.  
           [0007]    The ignition device may be of any desired type, for example, a piezoelectric ignition device, an electric ignition device formed by an incandescent filament or a purely mechanical ignition device. The ignition system operates reliably, since, owing to the short path the gas travels and the rapid flow of the gas around the igniter, the ignition operation can be reproduced and ignition failures avoided. “Gas supply” means those components of the gas combustion device which are connected to the gas valve for controlling the gas flow. Part of the catalyst may be provided in the bypass.  
           [0008]    In some preferred embodiments, the gas supply includes a first gas-permeable cover downstream of the bypass. The gas-permeable cover may act in a similar way to a throttle valve, so that a defined quantity of the gas arrives at the ignition device reliably and quickly via the bypass. The higher the gas permeability of the first cover, the more gas is supplied to the chamber of the catalyst and the less gas arrives at the ignition device.  
           [0009]    The outlet of the bypass may also include a second gas-permeable cover having a permeability selected in coordination with the first cover, to provide sufficient gas to the ignition device via the bypass. This second cover also has the advantage that the gas explosion advancing from the ignition device does not pass into the chamber of the catalyst via the bypass, but arrives at the catalyst only from outside via the space surrounding the catalyst.  
           [0010]    The first and the second covers may consist of a metallic screen, the passages of which pass through a sufficient quantity of the gas both to the catalyst and to the ignition device. The metallic screen of the second cover also may serve as a kind of gas throughflow limiter, so as not to allow too much gas to arrive at the ignition device. The two covers may also serve to improve the mixing of the gas when it flows through the covers.  
           [0011]    In some embodiments including the first gas-permeable cover, the gas supply includes a tubular housing for conducting the gas. The tubular housing includes an outlet, and the catalyst includes a bowl-shaped screen body with an inlet connected to the outlet. The first gas-permeable cover is positioned at a transition from the outlet to the inlet. This arrangement results in a particularly simple production of the gas supply device connected to the catalyst and to the cover, since the gas supply device can be produced easily and can be mounted in a simple way.  
           [0012]    In some embodiments including the tubular housing, the bypass comprises a slot at the end of the tube including the outlet. The slot is covered by the second cover. This arrangement also allows a simple production of the bypass at the gas supply device, in that a slot is formed laterally at the bore and is delimited at its orifice by the second cover.  
           [0013]    In other embodiments including the tubular body, the first cover and the second cover comprise a single covering part. The first cover includes an element having an essentially bowl-shaped cross section, with an adjoining annular flange, and the second cover includes a tab angled on the flange. The production, stock-keeping of parts and assembly of the appliance are simplified considerably owing to the one-part design of the first and second cover as a covering part. This lowers the costs of the appliance.  
           [0014]    In some embodiments including the single covering part, the bowl-shaped element is centered in the inlet. The covering part is positioned on the gas supply device in such a way that, at the same time, the tab covers at least part of the slot from the outside. This permits a simple connection of the catalyst to the cover and the gas supply device, in that the cover is centered on the gas supply device and the catalyst is in turn centered on the cover. The catalyst can thereby be connected firmly to the gas supply device, for example via a screw connection, adhesive bonding, plastic deformation or otherwise a generally known fastening device.  
           [0015]    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
       
    
    
     DESCRIPTION OF DRAWINGS  
       [0016]    [0016]FIG. 1 is a part longitudinal section through a gas-operated curler along the sectional line Y-Y in FIG. 2, in which only the gas supply device connected to the catalyst, the hot-air tube and a base part are illustrated;  
         [0017]    [0017]FIG. 2 is a cross section through the gas-operated curler in FIG. 1 along the sectional line;  
         [0018]    [0018]FIG. 3 is a perspective view of the catalyst with its gas supply device and the attached electrodes; and  
         [0019]    [0019]FIG. 4 is a perspective view of the covering part consisting of the first and second cover. 
     
    
       [0020]    Like reference symbols in the various drawings indicate like elements.  
       DETAILED DESCRIPTION  
       [0021]    Referring to FIGS.  1  to  3 , the curler or hair curler  1 , illustrated only partially, consists of a tube  3  which is provided with passages distributed on the circumference and in the chamber  4  of which is arranged a tubular catalyst  5  consisting of a lattice-like material. The tube  3  permeable to heating air is pushed on a centering stub  7  formed on a base  6  and is centered there. In this case, the free end  8  of the tube  3  butts against an end face  9  formed on the base  6  and in this position is connected fixedly to the base  6  via a fastening means not illustrated in the drawing. The base  6  is produced preferably from a plastic part shaped from temperature-resistant plastic. The base  6  serves as a receptacle for an ignition device, a valve device and a gas cartridge with housing, formed in a handle, which are not illustrated in the Figures, as is the case with regard to the appliance described initially.  
         [0022]    The base  6  has formed on it a centering pin  10 , on the outer face  11  of which a gas supply device  12  is centered and sealingly fastened. The gas supply device  12  is connected firmly to the base  6  via a fastening means not illustrated in the Figures. The gas supply device  12  consists essentially of a central tube  13 , the bore  14  of which narrows conically from right to left as far as a step  15 , thus ensuring better flow and mixing conditions of the gas/air mixture. From the step  15  on, the bore  15  then runs with a constant diameter as far as the outlet-side free end  16  of the central tube  13 .  
         [0023]    In particular, referring to FIGS. 2 and 3, three arms  17 ,  18 ,  19  distributed on the circumference are formed at the outlet-side free end  16  of the gas supply device  12  and at their front end have a stop face  20  (FIG. 3) lying at the same height.  
         [0024]    An annular collar  21  extending perpendicularly away from the tubular catalyst  5  bears against the stop face  20  and in the regions of the arms  17 ,  18 ,  19  has radially projecting fastening arms  22 ,  23 ,  24 . The fastening arms  22 ,  23 ,  24  are provided with holes  25 ,  26 ,  27  through which pass studs  28 ,  29 ,  30  projecting from the arms  17 ,  18 ,  19 . The catalyst  5  is thereby centered and fixedly held on the gas supply device  12 . The fastening of the catalyst  5  on the gas supply device  12  takes place in that the studs  28 ,  29 ,  30  after they have passed through the holes  25 ,  26 ,  27  according to FIGS.  1  to  3 , are deformed mechanically in such a way that they make a positive connection in a similar way to a rivet. The Figures illustrate the state just before deformation. In order to allow deformation more easily, the ends of the studs  28 ,  29 ,  30  are provided with oblique faces  63 ,  64 ,  65 .  
         [0025]    Referring to FIG. 1, a cap  33  which consists of the same screen material as the catalyst  5  is inserted into the bore  32  of the free end  31  of the catalyst  5 . At the free end  31  of the catalyst  5 , fine wire hairs  34  project, which, because of their low mass, serve as a starting aid during the ignition operation and thus bring the catalyst  5  itself to its incandescent temperature simply and quickly. Referring to FIG. 2, the tube  3  is designed with an essentially oval cross section and has a curved wall  35  which extends from the inner wall  66  inward into the vicinity of the catalyst  5  and which partially covers a thermostat  36  partially protecting the catalyst  5  against heat radiation. Both the thermostat  36  and the wall  35  run in the longitudinal direction and parallel to the catalyst  5 .  
         [0026]    Referring FIGS. 1 and 3, a sheet-metal strip  37  provided with anglings  67 ,  68  runs from the right, one portion  69  of which runs to level with the arms  17 ,  18 ,  19  and, angled there, terminates in an arrow tip  38 . A laterally arranged lug  39  thin in diameter and formed on the gas supply device  12  projects with a slight clearance. The lug  39  forms, with the arrow tip  38 , the ignition electrodes of the ignition device, via which electrodes one or more sparks flash over to the lug  39 , for example when a sufficiently high voltage is applied to the sheet-metal strip  37 . The sheet-metal strip  37  is, of course, insulated relative to the gas supply device  12  and to the housing parts of the curler  1  via insulating means which are not illustrated.  
         [0027]    A bypass  40  is formed in the gas supply device  12  at the cylindrical portion of the bore  14  and is delimited outwardly by a second cover  41  consisting of a wire lattice. As clearly shown particularly in FIG. 4, the second cover  41  describes part of a cutout of a hollow cylinder; the face of the outlet orifice of the bypass  40  runs parallel to said second cover, that is to say is curved in the same manner. The bypass  40  has an inlet orifice  42  and the outlet orifice  43 , the outlet orifice  43  adjoining the second cover  41 . According to FIG. 4, a flange  44  running transversely to the second cover  41  and forming the cutout of an annular disk runs laterally away from the edge  45 ,  46 , the center axis  70  of the flange  44  being at the same time the center axis  70  of the second cover  41 . A bowl-shaped first cover  47  adjoins the flange  44 .  
         [0028]    The first cover  47 , with its flange  44 , forms essentially a structure  62  having a hat with a rim, although the flange  44  is indented at two points  48 ,  49 , and this part, which forms the second cover  41 , is bent downwardly at right angles to the flange  44  via the bending line  50  and thus forms a tab  61 . However, in the not yet angled state, the second cover  41  of essentially rectangular cross section, that is to say the tab  61 , already projects radially outward at the rim  51  of the flange  44 , in order subsequently, in the bent-round state, to cover the entire cross section of the outlet orifice  43 . In alternative embodiments only part of the second cover  41  may cover the face of the outlet orifice  43 , particularly if sufficient gas/air mixture already arrives at the electrodes  38 ,  39  as a result and, at the same time, a sufficient amount of gas/air mixture likewise flows into the space  52  before the ignition operation and from there, via the gas-permeable orifices  53  of the catalyst  5 , into the chamber  4 .  
         [0029]    Referring to FIG. 3, a cutout  54  on the surface of the catalyst  5  shows that the wall of the catalyst  5  includes a large number of small orifices  53 , for example, a wire netting, through which the gas/air mixture can enter the chamber  4  before the ignition operation. The same applies to the first and second cover  47 ,  41  which are combined into a single covering part  55  and in which the material is likewise produced in lattice-form with small passages  56 . The covering part  55  is a punched, bent and pressed part, preferably consisting of fine wire fabric.  
         [0030]    The first cover  47  has a cylindrical portion  57  which is centered on the outside diameter  58  of the free end  16  of the gas supply device  12 . In this case, the disk-shaped portion  59  adjoining the cylindrical portion  57  completely covers the inlet orifice  60  of the catalyst  5  in this region and the bore  14 , as is shown in FIG. 1. Since the inlet orifice  60  of the catalyst  5  is larger than the outside diameter of the free end  16  of the central tube  13 , an annular inlet or outlet orifice  71  is obtained, via which gas/air mixture can likewise flow into or out of the space  52  of the catalyst  5 .  
         [0031]    The catalytic gas combustion device for a curler or hair curler  1  operates as follows:  
         [0032]    First, a gas valve, not illustrated in the drawing, is opened via a valve actuation element (not illustrated) arranged rotatably or displaceably on the base  6 . Gas flows via the gas cartridge, not illustrated in the drawing, through the valve device, is mixed with air and then passes, via a duct (not illustrated) formed in the base  6  in the drawing, into the bore  14  of the gas supply device  12  and is accelerated there (the conically narrowing bore portion  14  serves as a Venturi tube). The gas/air mixture then flows, on the one hand, through the disk-shaped portion  59  into the space  52  of the catalyst  5  and, on the other hand, also via the inlet orifice  42  into the bypass  40  to the outlet orifice  43  and from there into the chamber  4  surrounding the outer face of the catalyst  5 . Since the tips of the ignition electrodes  39 ,  40  are adjacent to the bypass  40 , the gas/air mixture flows around these immediately after leaving the outlet-side end  16  of the bore  14 . At the same time, the gas/air mixture located in the space  52  passes through the orifices  53  of the catalyst  5  into the chamber  4 , is distributed there and consequently also flows in the direction of the ignition electrodes  38 ,  39 .  
         [0033]    Even only a few seconds after the gas valve device is opened, then, an actuating knob fastened laterally to the base  6  in the drawing can be actuated, in order to actuate an ignition system not illustrated in the drawing. As a result, high voltage is applied to the sheet-metal strip  37  and therefore also to the arrow tip  38 . Due to the voltage difference between the arrow tip  38  and the housing-side grounded lug  39 , sparks (not illustrated) jump over from the arrow tip  38  to the lug  39 , by means of which sparks there is an immediate explosion of the gas/air mixture located in the surroundings of the ignition electrodes  38 ,  39 .  
         [0034]    The explosion wave then travels upward from the ignition electrodes  38 ,  39  as far as the wire hairs  34  which, on account of their low mass, are immediately brought to incandescence. The incandescence process is propagated from there via the edge of the free end  31  of the catalyst  5  until the entire catalyst  5  is incandescent. Catalytic combustion has commenced, and the combustion gases discharged as a result of combustion flow along in the chamber  4  and ultimately emerge outward as still hot gas from the passages  2  of the tube  3 . The tube  3  heats up, and after a short time the curler  1  is ready for operation, that is to say hairs can be laid around the outer face of the tube  3  and are then heated or even also additionally dampened by means of an evaporator device (not illustrated) integrated in the curler, so that long-lasting curls in the strands of hair can be formed quickly.  
         [0035]    The gas/air permeability of the first and second cover  47 ,  41  is dimensioned such that a sufficiently large quantity of gas/air mixture arrives at the ignition electrodes  38 ,  39  in a particularly short time. A sufficient gas/air quantity also simultaneously passes into the space  52  of the catalyst  5 . This ratio of the gas/air mixture distribution must be coordinated exactly, in order, on the one hand, to accelerate the explosion process in terms of time and also generally to improve it and, on the other hand, in spite of the bypass  40 , also to bring about sufficient catalytic combustion in the catalyst  5 . The gas/air mixture flowing via the bypass during operation then additionally supplies the chamber  4  with fuel, in order also to obtain particularly uniform catalytic combustion on the outer face of the catalyst  5 .  
         [0036]    After an operator has treated the hair by means of the curler  1 , the gas valve can be closed again and catalytic combustion is terminated, that is to say the curler  1 , but, in particular, the tube  3 , cools down again. The curler  1  can be laid to one side. It may also be mentioned at this juncture, that a closing cap (not illustrated) is present at the left free end of the tube  3 . This closing cap may, however, also be replaced by an evaporator device (not illustrated).  
         [0037]    Other embodiments are within the claims.