Electrical heating device for use with aerosol containers
BRIEF DESCRIPTION OF THE PRIOR ART 
     In recent years aerosol foam lathers have become popular for supplying shaving lubricants for man&#39;s seemingly never ceasing war with whiskers. For those who prefer a hot shaving lather, a major difficulty has been in obtaining sufficient heat for their lather, since mixing the aerosol lather with hot water sufficient to heat the lather often dilutes it beyond use. 
     A number of means of heating lather have been used, including chemical heating means added to the lather, heating elements within the aerosol lather can, and hot water reservoirs having heat transfer coils therein through which the aerosol foam from the can passes. 
     U.S. Letters Pat. No. 2,873,351 describes a device attachable to an outlet of an aerosol foam lather can to heat lather from the can, one embodiment having an electrical resistance coil around a lather channel in the device. An electrical outlet plug and length of electrical wiring is connected through switch means to the resistance coil, through which electrical energy is converted to heat the lather channel while in use. 
     U.S. Letters Pat. No. 3,644,707 is directed to a lather heating device in which heat energy is transmitted to a heat storage medium through a resistance coil attachable to an electrical outlet plug through a short length of electrical wire and male plug; or, in one embodiment, male plug prongs built directly into the device housing. The device uses no switches, fuses, or thermostatic controls to regulate temperature of the heat storage medium. A difficulty with the aforesaid device, however, is the difficulty in determining the temperature of the device; further, it is possible to leave the heating device plugged in while attempting to obtain lather which may subject the user to possible shock and electrical burns. 
     BRIEF DESCRIPTION OF THE PRESENT INVENTION 
     The present invention is directed to an improvement in lather heating devices attachable to aerosol containers and the like and comprises a truly portable housing having male electrical prongs built in thereto, the housing design being directed to minimizing overhang of the lather heating device while plugged into an electrical receptacle. The male prongs are connected to a heating coil through a thermostatically operated switch; the coil, when energized, transmitting heat energy proportionately through suitable heat transfer media to the switch and a heat sink having appropriately designed lather directing channels. When the desired heat temperature is reached, the thermostatic switch is opened from the heating coil and closed to a lamp to indicate readiness of the device for use. 
     The heating device must then be removed from the electrical receptacle before attachment to an aerosol container valve since the device adapter for the aerosol can is physically located on the same exterior surface as the male electrical prongs, and in a proximate position to prohibit simultaneous use of either an electrical wall outlet or extension cord and an aerosol can. 
    
    
     FIGS. 1 and 2 are perspective and side views of one embodiment of the lather heating device herein; 
     FIG. 3 is an exploded view of one heat exchange embodiment. 
     FIGS. 4 and 5 are alternative embodiments of the heat sink utilized in the present invention; and 
     FIG. 6 is a schematic electrical diagram of the circuitry utilized in the embodiment of FIG. 3. 
    
    
     FIGS. 1 and 2 show the exterior housing details of one embodiment of the portable, compact heating device of the present invention. The housing 1 is designed to bring the center of gravity of the device, when plugged into a wall receptacle, as close to the wall as possible to minimize torque exerted on the prongs 5 and 6. A nozzle 2 having a lather exit channel 3 is provided, the channel 3 leading back to a cavity 7A in which a heat sink means similar to that shown in FIG. 3 is located. An adapter 7 for an aerosol can valve also leads to the cavity 7A as discussed later herein. 
     Preferably, the prongs 5 and 6 are located proximate the aerosol can adapter 7 to prevent simultaneous use of an electrical wall outlet or extension with an aerosol can, thereby forcing the user to remove the prongs 5 and 6 from the electrical outlet before attaching the housing 1 to the aerosol can. 
     Additionally, a signaling means 4 such as an electrical lamp is positioned in housing 1 for ease of viewing and is energized upon attachment of a desired temperature. 
     The composite structure shown in FIG. 3 is located in the cavity 7A directly over aerosol can adapter orifice and comprises two discs 13 and 17 of aluminum or other high heat conductive material between which is sandwiched a third disc 15 of slightly smaller diameter having positioning tabs 16 more clearly shown in FIG. 4. Disc 13 is shown with appropriate sealing means 14, such as an &#34;o&#34; ring, to prevent escape of lather between the cavity 7A and disc 13 into the electrical section of the housing 1. 
     In the embodiment of FIGS. 3 and 4, a wafer heating coil 10 is formed with a support 11 of appropriate insulation means. Electrical wiring is as shown in FIG. 6. Support 11 is positioned between spacers 9 and 12 of high electrical resistance high thermal conductance material, such as mica. The thicknesses of spacers 9 and 12 are proportioned to transmit sufficient thermal energy to energize thermostatic switch 8 adjacent one spacer 9 simultaneously as heat sink discs 13, 15 and 17 have reached their desired temperature. 
     As indicated, discs 13, 15 and 17 act in conjunction as a heat sink in which thermal energy transmitted thereto by heating coil 10 is stored for later transfer to foam shaving lather passing through channels in the heat sink. FIG. 4 is illustrative of one embodiment and shows only discs 15 and 17; since, in this embodiment, disc 13 has simply a flat, smooth mating surface. 
     Disc 15 is smaller in diameter than disc 17 and therefore forms a channel 22 around disc 15 the depth of the disc 15 (shown in FIG. 2). Tabs 16 position the disc 15 so that the channel dimensions are substantially uniform. The tabs 16 are designed to permit lather flow around them, here simply being &#34;pinched&#34; to a height dimension smaller than the disc 15. 
     A channel 21a formed by the surface 21 and the mating surfaces of discs 13 and 17 directs lather coming into the channel an orifice 18 formed in this embodiment by a brad 19 extending through the aerosol can adapter 7 (FIG. 2) and disc 17. The brad 19 serves to prevent lather from getting underneath disc 17 during operation. The lather flows from the channel 21a around through channels 22 to notch 20 in disc 17 which directs the lather to the exit orifice 3 as shown in FIG. 2. The channels are designed (a) to provide sufficient contact of the lather to the heat sink to heat the lather to 120°-140° F, and (b) to restrict flow of the lather through the heat sink on a momentary impulse of an aerosol can valve to 3-5 grams of lather at the desired temperature. 
     In FIG. 5, an alternative embodiment of the heat sink of the present invention is shown sans disc 13 for the same reason above stated. Disc 23 has an opening around inlet 18 and brad 19. A channel 21a defined by surfaces leads out to channel 22 as in FIG. 4. Tabs 27 and 28 on disc 23 are bent into notches 28 and to locate disc 23 on disc 17 and to not impede flow of lather through channel 22 to notch 20 in disc 17, as described earlier. 
     In FIG. 6, prong 5 is connected through appropriate wiring to a two-position thermostatically controlled electrical switch 8. Male prong 6 is connected through electrical wiring 26 to one terminal of the heating coil 10, while the other terminal of coil 10 is connected to the normally closed contact terminal of switch 8. Electrical lamp 4 and appropriate protective resistance means R are connected in parallel with coil 10 through the normally open contact terminal of switch 8 to prong 6. 
     In operation, male prongs 5 and 6 are plugged into an appropriate electrical receptical, supplying electrical energy compatible with the components of the system and sufficient to excite the heating coin- here shown as conventional 110 volt alternating current (50-60 Hz). 
     An electrical circuit is completed through the normally closed contact of switch 8 and heating coil 10 until sufficient heat has been transmitted through disc 9 (FIG. 3) to heat the thermostat to an activating temperature, whereupon the heating coil circuit is broken and a circuit is completed through the normally open (now closed) contact of switch 8 and lamp 4 to indicate the desired temperature of the heat sink has been attained. The device may then be unplugged and attached to a nozzle valve of an aerosol can for actuation. Should the heat sink cool below a desired temperature range, the thermostatic switch will close and reenergize the heating coil if plugged into a receptacle until the desired temperature range is regained. 
     Adapter 7 is designed to fit over the nozzle valve of an aerosol can and support the housing 1 thereon. Sufficient clearance only is provided around adapter 7 to permit a simple push downward or sideways to actuate the aerosol can valve and release foam shaving lather. 
     EXAMPLE I 
     A lather heating embodying the arrangement of FIGS. 1, 2 and 5 is constructed, whereupon it is inserted into a 110 volt 60 Hz alternating current electrical outlet for 55 seconds until the temperature to the thermostat reaches 200±5° F., whereupon the thermostatic switch is activated closing the lamp circuit causing the lamp to glow. The temperature of the heat sink is measured to be 250° F. 
     The device is removed from the electrical outlet and affixed atop an aerosol shaving lather container. The housing 1 is pressed momentarily downward, releasing approximately 4 grams of lather into and through the heating device. The temperature of the lather at the exit orifice 3 is measured as 120° F. 
     EXAMPLE II 
     A device similar in all respects to Example I is constructed except the heat sink of FIG. 5 is substituted therein. Heating as in Example I is followed with a resultant approximate 5 grams of lather heated to 140° F. being produced. 
     While particular embodiments have been set forth herein, the present invention is not intended to be limited by the description, but is to be as set forth in the attached claims.