Aerosol heater with improved control means

Nov. 4, 1969

L. MARCOUX

3,476,293

AEROSOL HEATER WITH IMPROVED CONTROL MEANS

Filed Aug. 29, 1967'

Sheets-Sheet 1

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INVENTOR,

Leo Marcoux,

BY

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Nov. 4, 1969

L_. MARCOUX

3,476,293

AEROSOL HEATER WITH IMPROVED CONTROL MEANS

Filed Aug. 29, 196^

Sheets-Sheet 2

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INVENTOR,

JLiEO M^CLTCOICjC,

BY

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3,476,293

Patented Nov. 4, 1969

United States Patent Office

3,476,293 AEROSOL HEATER WITH IMPROVED CONTROL MEANS

Leo Marcoux, Pawtucket, R.L, assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of δ Delaware

Filed Aug. 29, 1967, Ser. No. 664,015 Int. Cl. B67d 5/62, 83/14

U.S. Cl. 222—146 14 Claims

ABSTRACT OF THE DISCLOSURE

A heater-dispenser device for heating fluid materials passing therethrough is disclosed. The heater consists of a spirally wound flattened tubular sheath containing an ¹⁵internal resistance heater electrically insulated therefrom. A solid-state element having a temperature-resistivity curve which reflects low resistance values at relatively low temperatures and relatively small changes in resistance with increasing temperature until an anomaly point is ²⁰reached at which point the resistance rapidly increases with slight increases in temperature. The element generates heat causing an increase in resistance until a thermal equilibrium is attained thereby limiting current flow. A lamp is employed as an indicator to show when the sys- ²⁵tem has generated sufficient heat and is ready for dispensing. One embodiment shows a heater-dispenser which is reciprocably mounted. A second embodiment shows a stationary heater-dispenser unit with reciprocably mounted actuating means. θ

Background of invention

This invention relates to an improved heater-dispenser 35 device for use with pressurized containers. More particularly , it relates to an improved device which can heat a fluid medium issuing from a pressurized package.

Pressurized containers have become widely used for packaging and dispensing fluids and fluid-like materials. 40 It is desirable to elevate the temperature of many such materials, such as, by way of example, windshield deicing fluids for automobiles, shaving lather, certain paints and varnishes, hot fudge and similar food items, and so on.

Various prior art devices have been designed for this 45 purpose. Generally they have been of two basic types as exemplified by the United States patent to Lannert, 2,873,351, issued Feb. 10, 1959. This patent discloses a heat exchanger which is attachable to the outlet of an aerosol container. Fluid medium is directed through the heat ₅θ exchanger as it is released from the container and is thereby heated. The heat exchanger is heated by an electric heater in one embodiment and by hot water in another embodiment. The subject matter of the instant invention relates to improvements on the first-mentioned embodi- ₅₅ment.

Aerosol containers employ a gas, such as Freon, under pressure to force the contents thereof out of the container when the discharge valve is open. Since the containers are fabricated from relatively thin gauge materials, it is im- ₆₀portant to keep the gas pressure at a safe level. Safe maximum temperatures, e.g., 120'° F., have been determined for such containers since elevating the temperature of the gas in a constant volume increases the pressure thereof. Heaters used with aerosol containers, to be safe must not θ.cause the temperature of the container to approach these levels.

Electric heaters in prior art devices have had certain inherent limitations, to name a few, they have necessitated relatively complex, expensive constructions in order 70 to provide adequate safety and to keep the heating device in the environs of a desired temperature by turning on and off the heating element current by use of movable contacts. They have drawn relatively large amounts of power, line voltage variations have caused variations in heater temperature, and extra parts have been required to calibrate the heaters and regulate the temperature thereof. In copending application No. 504,944, filed Oct. 24, 1965, now Patent No. 3,338,476, issued Aug. 29, 1967 an improved heater-dispenser is disclosed and claimed comprising a solid-state heater element having a large PTC characteristic which is used not only as a controlling element but also as the primary heating element.

Using the PAC element for the dual function of heating and controlling has solved many of the prior art limitations; however, for certain applications a less expensive structure is required.

One of the drawbacks which has prevented prior art devices from becoming commercially successful for many applications is that the cost of the device has been too high in relation to the cost to the consumer of the pressurized container making it less attractive to the consumer. With this as a design parameter along with the other prior art limitations referred to above applicant has invented apparatus which meets all of the criteria mentioned above, resulting in lower cost for the PTC element and a more efficient heat transfer from the heater to the fluid in the pressurized container while still maintaining the advantages of the system contained in my copending application.

It is therefore an object of this invention to overcome the disadvantages mentioned supra and to provide a simple, inexpensive, reliable, sturdy heating device which is easv to fabricate and useful with aerosol containers.

It is another object of this invention to provide a heating device useful with aerosol containers which results in minimal heat transfer to the container.

Yet another object is to provide an aerosol dispenserheater which has a self-regulated temperature and has inherent compensation for line voltage variations.

Another object is to provide a heater-dispenser which has a short warm up time and which is removably attachable to the outlet of the pressurized container to heat the contents as they issue therefrom.

The invention accordingly comprises the elements and combination of elements, features of constructions and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the appended claims.

In the accompanying drawings in which two of the various possible embodiments of the invention are illustrated:

FIGURE 1 is a circuit diagram of the circuit employed in the embodiments shown in FIGURES 2 and 3;

FIGURE 2 is a cross-sectional view of the device constructed in accordance with the invention with an elevational view of a pressurized container shown broken away;

FIGURE 3 is a cross-sectional view of a second embodiment of the instant invention with an elevational view of a container shown partly in cross-section and broken away.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Dimensions of certain of the parts as shown in the drawings have been modified and/or exaggerated for the purpose of clarity of illustration.

A device 10, constructed in accordance with the invention, is illustrated in FIGURE 2. A pressurized container 2, which holds material to be heated upon dispensing, such as shaving lather, mounts on its outlet stem 6 a heaterdispenser assembly 34. Assembly 34 comprises cup-shaped housing 36 provided with a central recession 38 which

3,476, 3 acts as a seat for the distal end portion of stem 6. An aperture 42 in the recession 38 is aligned to communicate with the bore of stem 6. Located in housing 36 is a heater formed of a thin tubular jacket 46 which closely encapsulates wire heating element 26. Jacket 46 is formed in a spiral providing a continuous spirally shaped passage 44 ⁸through which the foam material is adapted to pass. Jacket 46 may be constructed of any good thermally conductive material, such as aluminum. A conventional electrical insulation is provided in jacket 46 to prevent short circuiting. This may be effected, for example, by anodizing the aluminum in a conventional manner or by coating the internal surface with a thin layer of a conventional polymer. Cover plate 48 is fitted on top of housing 36 and attached thereto in any convenient manner as by crimping. 15 For reasons which will be explained below, in order to limit heat transfer from heater 26, cover 48 may be constructed of or coated with a thermal insulating material. Electrical insulation separate cover 48 from element 24, further described below. Housing 36 and cover 48 are 20 formed with egress portion 50.

Mounted on cover member 48 is a control element 24 composed of solid-state material which has as a chracteristic a large positive temperature coefficient of resistance (PTC). Polymers which can be crosslinked with carbon 25 or other elements, such as carbon black filled, cross-linked polyethylene, e.g., No. 4510 obtained from Cabot Corporation, 125 High St., Boston, Mass., are examples of one type of material. Another class of material is certain doped ceramics, such as, barium titanate doped with lan- 30 thanum, Ba.g₉7La.₀₀₃TiO₃. Reference may be had to U.S. Patent No. 3,338,476 for more detailed information on the preparation of this material.

PTC element 24 is provided with conductive terminal layers 25 on opposite sides thereof. Layers 25 may, for 35 example, be composed of a silver alloy coated by electroless soldering techniques known in the art.

Electrical insulation 64 which may be a conventional potting compound is conveniently employed as a support for several components of the device; viz, momentary con- 40 tact switch SW-1, lamp 18 and plug member 60.

Line current is conducted by a conventional two wire cord L_1; L₂. L, is connected to conductor 28, thence to one end of a standard resistance heater wire 26, the other end of heater wire 26 is connected by conductor 22 45 to one terminal layer 25 of the PTC control element 24. This layer 25 is also connected to one side of lamp 18 by conductor 20. The other layer 25 of PTC element 24 is connected to the other side of lamp 18 by conductor 16 and to one side of switch SW-1 by conductor 14. 50 Lastly, the other side of switch SW-1 is connected to L, by conductor 12.

Switch SW-1 is provided with a push button 62 which is biased upwardly by a spring (not shown). A stiffer spring 40 is mounted on stem 6 which biases assembly 34 55 upwardly as shown in FIGURE 2. The spring in switch SW—1 is such that it can be depressed by application of a force on button 62 to actuate the switch without causing spring 40 to be depressed. However, upon a greater force on button 62, the switch spring will act as a trans- go fer member and spring 40 will be depressed to actuate the valve of the pressurized contained.

Cover member 34 encloses the heater-dispenser unit 10 and is provided with apertures 52, 54 and 56 to allow access for plug 60, push button 62 and egress 50 respec- 65 tively. Aperture 56 is made large enough to permit lamp 18 to be seen by the operator of the device.

The operation of the device will now be explained. An initial force in the direction of arrow 63 is exerted on button 62 of switch SW-1 depressing it from the phantom line position shown in FIGURE 2 closing the momentary contacts bridging conductors 12 and 14 as best seen in FIGURE 1. It should be noted that this initial force is of a magnitude less than that required to depress spring 40 as explained above. Current flow through PTC mate293 rial 24 which in the cold state has a relatively low resistance and thence through the main heater 26 and back to L₂. Lamp 18 is preferably of the voltage sensitive avalanche type such as a neon lamp, so that initially it will not conduct at the low voltage generated across the cold PTC element. The PTC material used for effective operation of the device to permit close temperature control must have as a characteristic a large positive temperature coefficient of resistance, that is, material in which the percent change in resistance per degree change in temperature in the so-called break or anomaly point is very large. Current flowing through element 24 generates heat in the element raising its temperature until the anomaly point is reached beyond which point the resistance of element 24 rises very rapidly. The resultant voltage increase across the PTC element 24 causes the lamp to fire and also deenergizes the main heater 26.

When light 18 conducts the user then applies sufficient force to button 62 to depress spring 40 moving the assembly 34 from the phantom line position shown in FIGURE 2 to the full line position and thereby releases the pressurized material from container 2. The material in the container typically upon release from container 2 turns into a foamy substance containing many air bubbles and consequently is a very poor heat conductor. To optimize heat transfer from jacket 46 to the foam, the jacket is formed so that a maximum amount of surface area is exposed to the foam and the distance between the jacket walls. defining passage 44 is kept relatively small so that as much of the foam as is practically possible will come in direct contact with the heat exchanger.

As an example, in one device constructed in accordance with the above, the line voltage is divided so that initially there is about 20 volts across the PTC element and about 100 volts across the heater 26. A resulting current of 1 ampere causes 20 watts of heat generated in element 24 and about 100 watts in heater 26. The heater, due to its substantial heat mass, quickly heats up and stores the heat. The PTC element heats up due to its own heat generation and acts as a thermal analog of heater 26, The PTC element 24 employed has an anomaly at approximately 120° C. which is reached in about ten seconds. The PTC element 24 then takes virtually the total applied voltage, the heater voltage dropping to close to zero. Neon glow lamp 18 then turns on indicating that the system is ready to deliver hot aerosol fluid.

The system is especially useful for one shot type application since essentially all the heat generated by the heater is stored in the thermal mass of the heater with very little heat loss. The heater is thermally separated from surrounding parts consequently will lose most of its heat to the aerosol fluid when it is passed therethrough resulting in a very efficient device. As mentioned above, the PTC element 24 is designed so that it acts as a thermal analog of the heater therefore due to its own heat generating capacity it could be remotely located from the heater 26. Preferably the PTC element is kept to a small size and is used primarily as a control device and does not contribute any substantial heat to the system.

This system also provides compensation for line voltage variation. Low voltage will cause reduced current flow which will in turn result in lower power in both element 24 and heater 26. This will cause the PTC element 24 to. heat up more slowly and consequently power will be supplied to heater 26 for a longer time so that the total heat generated will be approximately the same. High voltage will cause just the opposite reaction in element 24 so. that power will be supplied to heater 26 for a shorter time and again approximately the same total heat will be generated.

It will be seen from the above that this device offers many advantages over various prior art devices. There is no standby power drain since the device is activated for only the short period required for warm up. The warm up is extremely fast. The neon glow lamp provides convenient

3,476,293 indication in comparison with copending application, now Patent No. 3,338,476, a lower cost PTC element design and an even more efficient heat transfer are provided.

It will be obvious to those skilled in the art that rather than using house current a rechargeable battery could be employed as the power source. The device could be connected to a charger when not in use.

If it is preferred to have the neon lamp glow until the warm up period is completed and then turn off, lamp 18 can be connected across heater 26 instead of PTC element 24.

Turning now to a second embodiment reference may be had to FIGURE 3. Device 100 is shown comprising essentially the same heating element (wire 26 and jacket 46) defining the same passage 44. Therefore, the description for this portion of the device and for the electrical circuit which is the same as that for FIGURE 2 and shown in FIGURE 1 will not be repeated. In this embodiment separate actuating means are provided for the heater circuit and for the actuator of the aerosol container valve. Further, the heater-dispenser assembly is stationary relative to support 134 resulting in a more durable device.

Electrical insulation or support 134 in this embodiment is molded of a conventional polymeric material and is provided with a chamber in which the heater jacket 46 is located. Plate 15# encloses passage 44 and is constructed out of heat and electrical insulation to provide thermal separation between the PTC element 24 and heater 26 providing more accurate control capability for the element 24. Support 134 is formed with a hub portion 145 which mounts a reciprocably movable slide 144 with an axial channel 146 therein. A bore 136 is provided in hub 145 in which motion transfer member 138 slides. A recessed annular area 140 is located in transfer member 138 to seat one end of spring 142. The other end of spring 142 is seated adjacent hub 145 causing transfer member 138 to be upwardly biased as seen in FIGURE 3. Button 166 is mounted in bore 167 of cap 158 and is adapted to contact transfer member 138. Stop member 168 is located on button 166 to limit the upward travel thereof.

Aperture 139 in hub 145 communicates with passage 44. Aperture 141 located in wall 148 of support 134 communicates with passages 44 and egress 141 in wall 148.

Button 160, slidably mounted in bore 164 of cap 158, is adapted to contact switch SW-1. A spring in switch SW-1 (not shown) biases button 160 upwardly, the movement of which is limited by stops 162.

Support 134 has lip members 132 and 152 which releasably snap on to the outer rim and nozzle 9 of container 3.

Cap 158 interfits with wall 130 of support 134 to enclose the device. Cap 158 has a transparent portion 172 to permit visual recognition of the energization of lamp 18.

In this embodiment the user initiates the warm up by depressing button 160 in the direction of arrow 161 from the phantom line position in FIGURE 3 to the full line position. This activates switch SW-1 and the heating action occurs as in the FIGURE 2 embodiment. When lamp 18 glows, the user then depresses button 166 in the direction of arrow 167 from the phantom line position to the solid line position which causes slide 144 to move downwardly dislodging the ball valve 8 from its seat permitting the fluid to discharge through channel 146, aperture 139 and into passage 44 wherein it is heated by contact with heat packet 46 and then is ejected through aperture 141 and out of egress 143.

Thus it will be seen that all the objects of the invention are fulfilled.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying draw ings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

As many changes could be made in the above constructions without departing from the scope of the invention, it it intended that all matter contained in the above description or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense.