BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a fog machine for generating and discharging fog used in photographic, motion picture, video production, and other entertainment industries. More particularly, the present invention relates to a fog machine configured to transform fluid into a cloud of fog substantially immediately upon energizing the fog machine.

2. Description of the Prior Art [0003] Devices that are used to generate fog in entertainment industries are well known in the art. Fog machines utilized for the purpose of generating fog consist basically of familiar, expected and obvious structural configurations, notwithstanding the myriad of designs encompassed in the crowded art which have been developed for the fulfillment of countless objectives and requirements.

[0004] For example, U. S. Pat. No. 4,836, 452 to Fox utilizes pressurized air delivered to an oil bath to generate a cloud of oil bubbles filtered on their way out. The disclosed structure including an air compressor that feeds high pressure air into multi-hole spraying pipes is cumbersome and requires substantial efforts to efficiently operate and be properly maintained. Most importantly, reaching a temperature sufficient to generate fog may take a substantial period of time after the entire machine has been turned on.

[0005] U. S. Pat. No. 4,990, 290 to Gill et al. is directed to a diffusion fogger provided with an air compressor delivering highly pressurized air to a nozzle wherein the delivered air atomizes oil drawn into it to produce fog. The fogger features a complicated structure requiring water separation from the delivered and cooled air as well as a compulsory feed mechanism for conveying the fog, generation of which requires substantial time, through an outlet.

[0006] U. S. Pat. No. 5,934, 080 to Foley et al. is directed to a process of generating fog by providing a transport vessel, and loading predetermined quantities of liquid oxygen and liquid nitrogen into the transport vessel. A means for periodic acceleration and deceleration of a mixture is designed to achieve a homogeneous mixture of the liquid oxygen and liquid nitrogen. Needless to say, the structure is not cost-efficient, requires a substantial time period to actually generate fog and has a complex geometry.

[0007] U. S. Pat. No. 6,006, 009 to Friedheim is directed to a heated vapor generator system including multiple vapor generators controllable to selectively generate heated vapor. Similarly to the above-discussed structures, the device disclosed in this reference tends to at least initially take a substantial amount of time to generate fog.

[0008] It is, therefore, desirable to provide an apparatus configured to generate fog substantially instantaneously.

SUMMARY OF THE INVENTION [0009] This objective is attained by a structure disclosed in the present invention and configured to heat a fluid such as a chemical liquid, which controllably fills a heating chamber, to a temperature sufficient to provide the vaporization of the mixture while it is filling the heating chamber. To provide a relatively instantaneous vaporization of the fluid, a heating element is cast into a plate, which is positioned within the heating chamber so that it maintains a direct contact with the fluid entering the heating chamber.

[000101 In accordance with one aspect of the invention, the bottom of the heating chamber, covered by the fluid controllably delivered into the heating chamber, is textured. Accordingly, the surface contacting the fluid is enlarged, if compared to a flat surface, and, as a result, the time period necessary for reaching a temperature sufficient to transform the fluid into a cloud of fog is substantially shortened.

[00011] In accordance with another aspect of the invention, the heating chamber is provided with a multiplicity of heating plates arranged so that while the incoming fluid is being guided between upstream and downstream heating plates, the entire volume of the delivered fluid reaches an elevated temperature sufficient for its vaporization. Thus, since the period of time, during which the delivered fluid advances towards the downstream heating plate, is very short, the fog machine produces fog practically instantaneously upon being turned on.

1000121 A further aspect of the invention provides with a metered delivery of fluid to be vaporized into a heating chamber. The fog production is instantaneous provided the desired volume of the fluid enters the heating chamber. Moreover, the textured surface accelerates the vaporization of the fluid when the latter fills the heating chamber up to a predetermined level. Generally, if the predetermined level is exceeded, the textured contact surface would not factor in production of fog, which, thus, would take a substantially longer time. Accordingly, the inventive fog machine is provided with a controller operative to communicate with various delivery devices to maintain a desired rate at which the fluid enters the heating chamber. The delivery process, accomplished by either a compulsory means or gravity, may be cyclical which allows the fog machine to continuously generate fog by replenishing the desired volume of the fluid in a controlled manner.

1000131 It is therefore an object of the invention to provide a fog machine having a simple, cost-efficient structure and capable of generating fog in a substantially instantaneous manner.

[00014] Still another object of the invention is to provide a fog machine with a heating chamber configured to accelerate the heating of fluid to be vaporized.

[00015] A further object of the invention is to provide a fog machine having a metered delivery of fluid to be vaporized on a continuous basis.

BRIEF DESCRIPTION OF THE DRAWINGS [00016] The above objects and other advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: [00017] FIG. 1 is a schematic view of a fog machine configured in accordance with the invention; [00018] FIG. 2 is a schematic view of the fog machine illustrated in accordance with another embodiment of the invention; [00019] FIG. 3 is cross-sectional view of a heating chamber of the fog machine shown in FIG. 1; and [00020] FIG. 4 is a perspective view of the heating chamber configured in accordance with another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION [00021] A preferred embodiment of the present invention will be described herein below with reference to the accompanying drawings. In the following description, like reference numerals identify similar or identical elements throughout the several modifications of the preferred embodiment, while well known functions or constructions are not described in detail so as not to obscure the invention in unnecessary detail.

[00022] Referring to FIGS. l and 2, a fog machine 100 is configured to transform fluid 18 delivered into a heating chamber 16 into a cloud of fog exiting a housing 10 through a nozzle 60 within a practically instantaneous period of time after the fog machine 10 has been turned on. Duration of physical transformation of the fluid 18 into the cloud of fog depends, among other parameters, on the vaporization temperature of the fluid 18, the volume of the fluid to be vaporized, the geometry of the heating chamber 16 and a heating element 30. Close proximity of the heating element 30 to a surface formed in the heating chamber 16 and covered by the delivered fluid 18 should be minimal to contribute to the effective transfer of heat, regardless of whether the heat transfer is realized by convection, conduction or radiation. Shaping the surface covered by the fluid 18 so as to increase its contact area with this fluid further facilitates effective heating and vaporization of the delivered fluid 18. Finally, prevention of accidental thermal trauma to a user who may be in physical contact with the housing 10 of the fog machine 100 dictates relatively low vaporization temperatures of the fluid 18.

[00023] Referring to FIG. 3, the heating chamber 16 is provided with a heating plate 36, made preferably from aluminum, which is cast with the heating element 30.

Alternatively, the heating element can be removably mounted to the heating plate 36.

While the heating element 30 may be a coil or wire, preferably it includes a ceramic rod or a U-shaped ceramic element functioning as a resistance heater upon applying voltage across terminals 31 (FIGS. 1 and 2) mounted to the rod, as is well known in the art.

[00024] A surface 37 of the heating plate 36 covered by the fluid 18, when the latter is delivered into the heating chamber 16, is located closely to the heating element 30. Accordingly, once the heating element 30 is energized, the surface 37 determining a contact area with the delivered volume of fluid 18, is heated to a temperature sufficient to vaporize the fluid 18 within a short, practically instantaneous period of time.

[00025] To effectively minimize the period of heating, the heating plate 36 is shaped to have troughs and peaks formed on opposite surfaces thereof to increase the contact area between the surface 37 and the delivered fluid 18. A shaping pattern can vary and, as exemplified in FIG. 3, includes corrugations formed along a fluid path 34, which is defined between inlet 32 and exhaust 28 pipes sealingly mounted to the heating chamber 16 and traversed by the fluid 18 and fog, respectively.

[00026] Furthermore, a radius of corrugations of the surface 37 is selected so that by the time the fluid 18 reaches a downstream stretch of the fluid path 34 adjacent to the exhaust pipe 28, the entire volume of the delivered fluid 18 can be vaporized. Thus, the pattern formed on the surface 37 not only increases the contact area, but controllably impedes the advancement of the fluid 18 along fluid path 34 of heating chamber 36.

[00027] Fig. 4 illustrates an alternative embodiment where the heating chamber 16 houses a plurality of heating plates 38,40, 42 and 44 arranged to controllably guide the incoming fluid 18 to the downstream plate 44. The upstream plates 38-42 are horizontally inclined and arranged in a staggered manner, wherein free ends of these plates overlap one another to provide gradual vaporization of the entire volume of the fluid 18 by the time it reaches the horizontally positioned downstream plate 44. The heating plates may each have a respective heating element 30, configured as explained in reference to the embodiment illustrated in FIG. 3, or may comprise electrodes directly energized to heat the fluid themselves. The heating plates are formed with a guide channel (not shown) shaped to securely guide the fluid 18 along its path toward the downstream plate 44. Dimensions and shapes of the heating plates may vary, but in order to efficiently convey the fluid, the width of the plate is preferably at least equal to a cross- section of the inlet pipe 32. Furthermore, each of the installed heating plates can be uniquely shaped and dimensioned subject only to the total vaporization by the time the downstream plate 44 receives a not yet transformed portion of the fluid 18. As an example, the heating plates may have a polygonal or oval shape, wherein opposite sides converge towards one another to form a channel. Alternatively, the heating plates may be flat, but provided with guiding channels shaped and dimensioned to receive and contain the running fluid so it would not overflow the channels. Similarly to the initial embodiment of the invention, the heating and vaporization of the fluid 18 occurs practically instantaneously after the heating elements have been energized.

[00028] The heating chamber 16 is formed within a casing, which can be shaped and dimensioned in a variety of ways all subject to the effective and fast vaporization of the fluid 18. As shown in FIGS. 3 and 4, the inlet and exhaust pipes 32,28 are preferably aligned. However, a simple modification of the heating chamber 16 would allow the exhaust pipe 28 or even a plurality of the latter to open laterally relative to the direction of the fluid path in the chamber. Furthermore, the structure illustrated in FIG. 3 is not limited to a single heating element, nor are the heating plates limited to any single suitable metal.

[00029] In both embodiments of the heating chamber 16, the volume of fluid delivered into the heating chamber 16 is metered so as not to exceed a predetermined level. Ideally, referring, for example to FIG. 3, the fluid 18 only slightly covers the surface 37 of the heating plate 36 without reaching any substantial depth. Otherwise, the fog generation can be a time-consuming process defeating the purpose of the inventive machine. Accordingly, as shown in FIGS. 1 and 2, the fog machine 100 has a controller 22 operative to maintain the desired rate of fluid delivery into the heating chamber 16.

[00030] Referring specifically to FIG. 1 illustrating the delivery of the fluid 18 by gravity, the fog machine includes a valve 24 controllably closeable to interrupt the flow of fluid so as to allow only the desired or metered volume of the fluid to enter the chamber 16. The valve 24 can be a mechanically operated valve, such as float and lever valves designed to control the level and flow of liquids. This can be done by manual operation, float boxes or mechanisms, electric motors or other actuators, as known in the art. If the valve 24 is electrically powered, the fog machine 100 may have an actuator 25 periodically opening the valve 24 based on a known time interval sufficient for the previously delivered volume of the fluid to vaporize. Preferably, the inlet pipe 32 is slightly inclined with respect to a horizontal to improve the delivery of the fluid 18 in the heating chamber 16.

[00031] The safe operation of the fog machine 100 is provided by a level sensor 46 located in the reservoir 20 and generating an alarm signal in response to reaching a low reference fluid level. The controller 22 receiving the generated signal sends a control signal to the actuator 25, which is, thus, prevented from being energized. The fog machine may have a light or sound indicator warning the user about the low level of fluid. Having a metering system including the valve 24, the inventive fog machine 100 can operate on a continuous basis, providing metered portions of the fluid into the heating chamber 16 as long as the reservoir 20 contains a sufficient fluid volume.

(00032] FIG. 2 illustrates another embodiment of the fog machine 100 having a compulsory supply of the fluid 18 in the heating chamber 16. A pump 26, located along the fluid path between the reservoir 20 and the heating chamber 16, is periodically actuated by the controller 22 to supply a metered volume of the fluid 18 into the heating chamber 16. Similarly to the above-disclosed embodiment, the fog machine illustrated in FIG. 2 operates on a continuous basis as long as the level of the fluid 18 in the reservoir 20 is acceptable. In additional, it is possible to interrupt the cyclical operation of the fog machine and generate a single cloud of fog if such an operation meets the user's needs.

[00033] To minimize the risk associated with elevated temperatures generated during the operation of the fog machine 100, both the perimeter of the heating chamber 16 and a lid 12 and walls 14 of the housing 10 can be provided with heat-insulating layers 52 and 54, respectively. Actuating the fog machine may be provided from a remote location. Dimensionally, the fog machine 100 can be carried by the user and has at least one handle 50 mounted to the housing 10. The nozzle 60 (FIG. 1) of exhaust pipe 28 can be further attached to any fog conveying element including hoses, pipes and the like.

Conveniently, the fog machine 100 can be provided with a remote control 48 (FIG. 1) coupled with all electrically powered components of the machine.

[00034] It should be clear that the optimum dimensional relationships for the parts of the invention may include variations in size, materials, shape, form, function and the manner of operation, assembly and use, and would be deemed readily apparent to one skilled in the art. All equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention, as recited in the appended claims.