Immersion Heater

Abstract

Electrical liquid-heating apparatus for rapid heating of small unit volumes of a liquid such as water in which a unit volume container is provided with a heating element at its upper end, and a partially closed top supports an upper well, heating of the water within the container driving a certain portion of the water upwardly into the well, and a recirculation conduit carries the water from the well downwardly to the bottom of the container, the whole structure being sealed within a housing, water being drawn into the housing and container from an outside source by means of a vacuum, and the heated unit volume of water being drawn off from the container by means of the same vacuum.

Description

The present invention relates to an electrical immersion heater for heating small unit quantities of liquid such as water, and is particularly designed for employment in a beverage-dispensing system installed in automobiles.

In beverage-dispensing systems of this type, water and other beverages are stored in suitable plastic containers in the trunk of the automobile and a dispensing console is mounted in the passenger compartment of the automobile connected to the liquid storage containers by means of a system of pipes, and the liquid is drawn from the container into the console, and simultaneously dispensed from the console into a cup by means of the vacuum induced in the inlet manifold of the automobile engine. In order to provide a selection of different beverages, both hot and cold, some means of heating the water, as it is drawn from the container to the console, must be incorporated which will heat the beverage or water to a temperature preferably in the region of 180.degree. F. or thereabouts, or in any event, somewhat higher than is suitable for drinking. One form of such beverage-dispensing system is disclosed in United Kingdom Pat. No. 1,084,834, although obviously the present invention may find employment in other forms of beverage-dispensing system both in automobiles and elsewhere. One form of water-heating system which has been employed in the past, in the aforesaid beverage-dispensing system referred to, has been in the form of a heat exchanger with a central bore connected to the coolant system of the automobile, and an outer jacket through which the cold water was drawn and thereby raised to the temperature of the coolant. While this system is highly efficient, it incorporated certain disadvantages. Thus, for example, the system did not become operative until the engine had been run for some time sufficient to raise the coolant temperature substantially. Secondly, it involved fairly radical modification of the automobile coolant system resulting in certain minor problems with regard to, for example, manufacturers' guarantees on the original automobile and the like, and the labor involved was fairly substantial and such heat exchanger occupied a considerable space in the engine compartment. As a result, it was somewhat difficult to install in smaller types of cars, and, of course, made it impossible to install such dispensing systems in cars without a liquid coolant system.

Accordingly, the present invention seeks to provide an electrical immersion heater designed particularly for use in connection with such a beverage-dispensing system although obviously having other applications, in which a small predetermined unit quantity of water or other liquid is rapidly heated in a very short time, and which is entirely automatic in operation and which cannot suffer any ill effects from cold weather and the like and which is adapted to be operated by power supplies of typical automobiles.

More particularly, it is an objective of the present invention to provide a immersion heater having the foregoing advantages which is a completely sealed system free from any contamination, in which the act of withdrawing a predetermined unit quantity of liquid also results in the immersion heater being replenished with the same quantity of liquid whereby to provide for continuous operation.

More particularly, it is an objective of the present invention to provide an immersion heater having the foregoing advantages in which the unit volume of water actually being heated is located in an inner container which is surrounded by an outer jacket containing a further unit volume of liquid which is preheated to some degree during the heating of the liquid in the inner container.

More particularly, it is an objective of the present invention to provide an immersion heater having the foregoing advantages in which the water being heated is subjected to a circulating action thereby increasing the speed with which the entire unit volume is brought up to the desired temperature.

More particularly, it is an objective of the present invention to provide an immersion heater having the foregoing advantages which is designed for incorporation in a continuous fluid supply system for use in an automobile in which the liquid supply and the dispensing location may be located at various different elevations with respect to the immersion heater, and in which syphoning effects are rendered impossible notwithstanding any such variations.

The foregoing and other objectives will become apparent from the following description of a preferred embodiment of the invention which is given here by way of example only with reference to the following drawings in which like reference devices refer to like parts thereof throughout the various views and diagrams and in which:

FIG. 1 is an exploded perspective view, partially cut away, of an immersion heater according to the present invention, and,

FIG. 2 is a section along the line 2--2 of FIG. 1.

With reference to the drawings, it will be noted that the immersion heater according to the invention consists essentially of an inner heating chamber indicated as C and an outer preheating jacket indicated as J, inner chamber C. Being of predetermined unit of volume equivalent to the volume of approximately two to three normal drinking cups, the outer jacket J has a volume which is more or less equivalent, or slightly less than that of the chamber C.

Dealing first with chamber C, it will be seen that this is formed of a cylindrical container member 10 of plastic or the like material mounted on a base 11 to which it is sealed by means of the annular wall 12 integrally molded with base 11 for the purpose. An electrical immersion heater element 13 is formed into a coil within container 10 and terminals 14 extend outwardly from base 11 for connection to the power supply of an automobile, through any suitable switching means (not shown) which may be operated by a passenger in the automobile. Integrally molded with container 10 there is an upper flattened top member 15 having a group of liquid passageways 16 passing therethrough, and an upstanding annular wall 17 surrounding the group of passageways 16 and separating them from the remaining outer portion of top member 15. Within container 10, and integrally molded therewith, there is provided the central liquid circulation column 18 which consists essentially of a tube open at both ends, the upper end thereof designated as 19 communicating through top member 15 and into the area surrounded by annular wall 17, whereby to permit any liquid which may have expanded and risen upwardly through passageway 16 to return down into container 10 through tube 18 somewhat in the manner of a percolator thereby providing a continuous liquid circulation. It will be understood that in order to produce the greatest effectiveness, and ensure that such liquid circulation takes place as quickly as possible after commencement of heating, the element 13 is preferably placed at the upper end of container member 10, and between container 10, and the downwardly dependent portions of passageways 16, thereby ensuring that water or other liquid heated by such element 13 rises directly upwardly within container 10, and is trapped between container 10 and top member 15, at which point it generates a certain amount of water vapor and steam which cannot escape due to the fact that the downwardly dependent portions of passageways 16 are immersed in water. The trapped water vapor and steam will thus develop a localized pressure which will force water upwardly within the passageway 16 to commence the circulation within container 10. It will be understood that the reference to a percolator action is only approximate, since the circulation in the case of the present invention takes place in a direction which is essentially opposite to the circulation within the normal percolator.

The outer preheating jacket J consists of a cylindrical container 20 having an integrally molded top 21, and being adapted to be closed and sealed at its lower end by base 11 which is provided with an outer annular rim or wall 22 dimensioned to fit snugly around the exterior of container 20 and make sealing engagement therewith. At the upper end of container 20 a downwardly dependent annular baffle member 23 is integrally molded with top 21, having an outer diameter equal to the outer diameter of container 10, and being of such a height as to define a predetermined spacing between walls 23 and the top surface 15 of container 10 for flow of liquid therethrough.

In order to provide for a self-regulating liquid inlet, an inlet spigot connection 24 is integrally molded with the top 21 of container 20, and an inlet conduit tube 25 is integrally molded in registration with spigot 24 whereby to conduct incoming water from spigot 24 directly to the lower region of jacket J. An outlet spigot 26 is integrally molded on the central axis of top member 21 for connection to a vacuum withdrawal system (not shown), and makes communication with liquid withdrawal tube 27 integrally molded on the interior of top member 21, which is of such a length as to enter the upper end 19 of tube 18.

A safety valve is provided in the form of the valve socket 28 integrally molded with top member 21, and valve screw 29, by means of which imbalance of pressure resulting from heating or subsequent cooling of the unit, which will result in development of elevated or reduced pressures respectively, may be corrected. As an additional safety measure, any suitable form of temperature limit switch (not shown) may be attached to base 11, for example, and connected in circuit with the electrical supply system, whereby to avoid damage to the unit due to overheating. It will be understood that the safety valve described above, is essentially a two-way pressure relief valve, which operates to relieve either excessive pressures or reduced pressures within the immersion heater unit, the screw thread around screw 29 merely providing a restricted flow path for air or water vapor, passing out of or into the immersion heater unit, but preventing flow of water or other liquid therethrough.

In order to prevent any reverse syphoning action, a check valve is provided at the lower end of inlet conduit tube 25, consisting of the wire mesh disc 30, and the flexible plastic or rubber diaphragm 31 which is formed with the generally star-shaped cuts or incisions 32 therein. Diaphragm 31 and wire mesh disc 30 are retained at the lower end of tube 25 by means of the retaining collar 33 which is formed to fit tightly over the end of tube 25 and is retained thereon by adhesive or other suitable means.

In operation, a liquid supply, for example, a water supply in the trunk of an automobile may be connected by a suitable liquid conduit to inlet spigot 24, and a vacuum hose, for example, connected from the dispensing console in passenger compartment of an automobile may be connected to outlet spigot 26. Upon the opening of the vacuum line, the air contained within container 10 and outer container 20 is progressively exhausted, thereby causing induction of water through inlet spigot 24 and down tube 25. Such water will then fill the outer jacket J and as soon as it reaches the upper edge of container 10, it will flow between top 15 and downwardly dependent wall 23 and will then rise upwardly and overflow over the top of upstanding wall 17. The liquid will then flow downwardly to opening 16 and fill container 10 and tube 18, and will then flow upwardly through tube 27 and outlet spigot 26, and then be delivered to the dispensing console (not shown) in the passenger compartment of the automobile. As soon as cold water is delivered in the passenger compartment, the vacuum will then be closed off by a suitable valve provided for the purpose (not shown) and the electrical power supply will be switched on, thereby heating the immersion heater element 13. The water surrounding element 13 will rapidly be heated up, since it consists at the most of 10 or 12 fluid ounces, and by convexion, the heated water will rise upwardly and be trapped by the top member 15 and the downwardly dependent portion of passageway 16, in which region water vapor or steam will be developed causing localized increase of pressure which will thus force the water or other liquid within the container 10 to flow upwardly through opening 16 into the space or well defined by wall 17 and pass through the open top 19 of tube 18 and flow downwardly in tube 18 to the lower end of container 10. Simultaneously, the cold water within tube 18 will of course flow downwardly and into the lower end of container 10 whereupon it will be immediately heated and the circulation of water will continue until the whole contents of container 10 and tube 18 are brought up to a predetermined maximum temperature, generally in the region of about 180.degree. F. At this point, by any suitable switching means (not shown) the element 13 may be switched off, or may alternatively be switched to a position of a reduced power, and the passenger within the automobile will then again open up the vacuum line and draw off the contents of container 10 and tube 18 through tube 27 and spigot 26. As such heated liquid is drawn off, further liquid is drawn from jacket J in the same manner as described before. Obviously, the water in the jacket J has been, to some extent, preheated due to its close proximity with the exterior of container 10, and so will be brought up to the desired maximum temperature by element 13 much more quickly, thereby permitting the passenger in the automobile to dispense one cup after another of hot beverage almost without delay.

It will be understood from the foregoing that the immersion heater unit, according to the invention in its normal operation condition, will be filled with liquid, under normal operating conditions, more or less up to the upper edge of the wall member 17, the remaining portion being filled with air. However, as the temperature of the water within container 10 rises, pressures will develop which must be relieved to avoid damage to the unit. This is achieved through the medium of the pressure relief valve housing 28 and valve screw 29, which permits excess air and water vapors to escape slowly. As the unit cools down, air can bleed back into the unit through the safety valve housing 28 and screw 29 in order to compensate for any loss of pressure within the unit which might cause damage. In addition, it is found that by the use of a sealed heating unit, which communicates to the atmosphere only through a restricted safety valve such as that in the present invention, any tendency for the liquid to syphon either into or out of the unit is completely eliminated. In addition, the possibility of reverse syphoning upon cooling is further reduced by the action of the diaphragm 31 and the wire mesh disc 30. Thus when water is flowing downwardly through tube 25, such water will cause the diaphragm 31 to be distended and it will flex downwardly thereby permitting such water to flow freely therethrough, and through the collar 33 as desired. However as soon as any such water attempts to reverse such flow due to syphoning effects, for example, the diaphragm 31 is held closed by means of the wire mesh disc 30, and cannot pass any substantial volume of water therethrough.

The foregoing is a description of a preferred embodiment of the invention and is given here by way of example only. The invention is not to be taken as limited to any of the specific features as described but comprehends all such variations thereof as come within the scope of the appended claims.

Claims

What I claim is:

1. Electrical liquid heating apparatus for rapid heating of small unit volumes of liquid and comprising:

a unit volume liquid container having sidewalls, a bottom and a top;

upper wall means having a predetermined height defining a liquid well on the upper surface of said container top;

at least one tubular conduit fastened to said container top and having one end open to said well, below said predetermined height and the other end opening into said container adjacent the bottom thereof for conducting liquid from said well downwardly into said container and delivering the same adjacent the bottom thereof;

electrical heating element means supported within said container and extending around the same adjacent the upper end thereof;

a plurality of liquid passageways connected to said container top and communicating between said container and said well, heating of said liquid in said container by said heating element producing displacement of liquid upwardly through said liquid passageways into said well for subsequent recirculation downwardly through said conduit into the lower end of said container;

a housing sealed around and enclosing said container and said liquid well means thereon and defining a jacket surrounding the same for containing additional liquid outside said unit volume container and communicating with said container only through said liquid well for passage of said liquid therein from said housing;

inlet means for introducing liquid within said housing, and,

outlet means for connecting said housing to any suitable conduit for removing liquid from said housing and container.

2. Apparatus as claimed in claim 1, wherein said liquid container is of an upright, cylindrical shape, and wherein said wall means comprise an annular upstanding wall arranged on the upper surface of said container top, said tubular conduit being arranged along the central axis of said container, and said plurality of liquid passageways being arranged around said tubular conduit within said wall means.

3. Apparatus as claimed in claim 1, wherein said outlet means are adapted for connecting said housing to any suitable vacuum source for drawing liquid into said housing and container under vacuum and filling the same.

4. Apparatus as claimed in claim 1, incorporating pressure relief opening means in said housing.

5. Apparatus as claimed in claim 1, wherein said housing is of upright cylindrical shape, of larger internal diameter than the external diameter of said container and defining a generally cylindrical spacing therearound for containing additional liquid, and a liquid inlet tube opening into the lower end of said housing between said housing and said container, and a one-way valve in said tube.

6. Apparatus as claimed in claim 1, including a liquid withdrawal tube extending from the interior of said housing into said tubular conduit within said container, said withdrawal tube communicating with said outlet connection means on said housing.

7. Apparatus as claimed in claim 1, including a downwardly dependent flange member within said housing arranged and dimensioned to extend around said wall member on the upper surface of the top of said container.

8. Apparatus as claimed in claim 7 wherein said liquid passageways in said container top include downwardly dependent portions extending into said container a predetermined distance locating same below the normal liquid level therein for entrapment of water vapor in the upper end of said container.