Abstract:
Heat energy is converted into mechanical energy through the mobilization of electrical charges within a thermoelectric material. A plurality of plugs of thermoelectric material are mounted on a rotor. Heat energy is directed to one end of each of the plugs. The heat energy mobilizes free charges in the plugs which collect at the relatively cooler end, thereby electrically polarizing the plugs. A pulsed electromagnetic force field acts upon the polarized plugs to exert a torque on the rotor.

Description:
RELATED APPLICATION 
     This application claims the benefit of provisional application Ser. No. 60/299,358 filed Jun. 19, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to the field of prime movers. More specifically, the invention relates to an engine that converts heat energy to mechanical motion through the mobilization of electrical charges within a pulsed electromagnetic force field. 
     2. Background 
     Numerous technologies are available for converting heat energy into mechanical motion. The operating principles of the steam engine were demonstrated in ancient Greece. In 1821, the Seebeck effect was discovered, wherein an electrical current flows between junctions of dissimilar materials maintained at different temperatures. Thermoelectric devices utilizing the Seebeck effect are capable of converting heat energy into useful amounts of electrical energy. The electrical energy, in turn, may be converted to mechanical energy by means of a conventional electrical motor. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a novel method for converting heat energy into mechanical energy through the mobilization of electrical charges within a thermoelectric material. The mobilized charges create a voltage differential within the thermoelectric material. A pulsed electromagnetic force field exerts a force on the polarized thermoelectric material, which is harnessed as mechanical energy. In one embodiment of the invention, a plurality of plugs of thermoelectric material are mounted on a rotor. Heat energy is directed to one end of each of the plugs, thereby electrically polarizing the plugs. A pulsed electromagnetic force field acts upon the polarized plugs to exert a torque on the rotor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A illustrates a first type of thermoelectric material that may be utilized in the present invention. 
     FIG. 1B illustrates a second type of thermoelectric material that may be utilized in the present invention. 
     FIG. 2 is a cross-sectional view of an engine constructed in accordance with one embodiment of the present invention. 
     FIG. 3 is a detailed view illustrating a plug receptacle in the rotor of an engine. 
     FIG. 4 is a detailed view of a plug assembly for installation in the receptacle of FIG.  3 . 
     FIG. 5 is a detailed view illustrating an alternative plug design. 
     FIG. 6 illustrates an engine in accordance with an embodiment of the present invention using a multilevel rotor. 
     FIGS. 7A,  7 B illustrate another plug design. 
     FIG. 8 illustrates yet another plug design. 
     FIGS. 9A,  9 B illustrate an engine constructed in accordance with another embodiment of the present invention. 
     FIG. 10 illustrates magnetic shielding of the magnets to enhance engine performance. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods and devices are omitted so as to not obscure the description of the present invention with unnecessary detail. 
     An engine constructed in accordance with the present invention utilizes a plug of a thermoelectric material such as shown in FIG.  1 A. When heat is applied to end  12  of plug  10 , free electrical charges within the material flow towards and collect at the opposite end  14  of the plug. A plug made of an n-type semiconductor material is shown in FIG.  1 A. Such a material is rich in free electrons—on the order, for example, of 10 19 /cm 3 . A plug  20  of a p-type semiconductor material is shown in FIG.  1 B. The operating principle is identical, except that the material has a surplus of free positive charges. 
     When a thermoelectric plug such as shown in either of FIGS. 1A or  1 B is placed within an electromagnetic force field, a force is exerted on the plug, the direction of the force depending upon the respective polarities of the plug and the force field. The engine of the present invention harnesses this force in the form of mechanical energy. 
     FIG. 2 is a cross-sectional view of an engine  100  that operates on the above-described principles. A rotor assembly  102  is mounted on bearings  103  within a stationary housing  104 . A plurality of plugs  106  of thermoelectric material are installed in the rotor assembly. As explained above, each of plugs  106  is made of a suitable thermoelectric material, such as highly doped n-type or p-type semiconductor material or other similar material with an abundance of free electrical charges. The plugs are heated from within the rotor assembly by heater rods  108 . A temperature controller (not shown) regulates the amount of heat transmitted by rods  108  so that plugs  106  are maintained at their optimum working temperature. Any source of heat energy may be employed. For example, heater rods  108  may be connected to a solar collector. Alternatively, heat may be supplied from combustion of conventional fuels, from geothermal sources or from chemical or nuclear reactions. The source of heat may be waste heat from industrial processes that would otherwise be released into the environment. The ends of the rotor assembly are sealed by caps  105 . Mechanical energy is transmitted from engine  100  via shaft  107 . 
     Electromagnets  110  are disposed on the housing  104 . The electromagnets are energized by control module  112 , which receives electrical power from battery  114 . Control module  112  energizes the electromagnets to generate a cyclical or pulsed electromagnetic field. Thus, the control module functions as a commutator to pulse the electromagnetic field so that the forces exerted on the plugs of thermoelectric material produce continuous rotation of the rotor  102 . Sensor  116  is coupled to control module  112 . Sensor  116  senses the rotational position of rotor assembly  102  and may also sense the rotational velocity. The electromagnets  110  are pulsed in synchronism with rotation of the rotor assembly. The pulse frequency is also a function of the angular spacing of the plugs and electromagnets. 
     Referring to FIG. 3, the rotor assembly  102  has an outer shell  120  comprising an inner structural skin  122 , an outer structural skin  124  and a structural foam core  126 . Such construction provides a high strength rotor that is low in cost and light in weight. The inner and outer skins may be made of a filament-wound, fiber reinforced composite material. Rotor shell  120  is fabricated with a plurality of slots or cutouts  128  to receive the plugs of thermoelectric material. Slots  128  are oriented at an angle θ with respect to the circumference of rotor shell  120 . The value of the angle θ is dependent on the characteristics of the thermoelectric material used for plugs  106 , the characteristics of the electromagnetic field generated by electromagnets  110  and the design rotational speed of rotor assembly  102 . A magnetically shielded insert  130  with internal threads is bonded into each of the slots  128 . 
     Referring next to FIG. 4, each of the plugs  106  is bonded into a high temperature plastic insert  132  with external threads. The assembly of plug  106  and insert  132  is then screwed into insert  130  in the rotor wall. A spring lock mechanism (not shown) may be applied to each of the plug assemblies to prevent loosening of the threads during operation. Alternatively, the mating threads may be formed with an interference fit or other mechanical or chemical locking means may be employed. 
     Housing  104  may be made of a fiber reinforced composite material as in the case of rotor shell  120 . The housing may be fabricated in two halves to ease assembly and may be perforated with cooling vents to aid in cooling the outer skin of rotor shell  120 . As mentioned above, electromagnets  110  are secured to the inner surface of housing  104 . The electromagnets are arranged in an appropriate pattern to complement the arrangement of plugs  106 . 
     As described above, electromagnets  110  are energized by control module  112  which receives electrical power from battery  114 . To conserve battery power, coils of conductive wire may be embedded in the outer skin  124  of rotor shell  120 . As the rotor assembly rotates, current is induced in the coils by the electromagnetic field generated by electromagnets  110 . This current may be used to power control module  112  so that current from battery  114  is required only during startup. 
     An alternative design for a plug  140  is illustrated in FIG.  5 . This plug is generally in the shape of an hourglass and is heated from both inside and outside the rotor shell. Charges collect at the narrowed center portion  141  of the plug, thereby effectively doubling the number of plugs. Air passages are designed into the rotor shell and insert  142 . Cooling air is routed through the rotor wall to cool the center portions of the plugs so as to maintain the necessary temperature differential for charge collection. 
     FIG. 6 illustrates an alternate rotor design with multiple concentric levels. Plugs  106  (or plugs  140 ) are installed in annular walls  152  and  154 , thereby increasing the number of plugs in the engine and significantly increasing the output power. 
     FIGS. 7A,  7 B illustrate another alternative plug design. Plug  160  is configured with a plurality of slots or cutouts  162 . By virtue of these cutouts, the application of heat at end  164  of the plug creates a continuous flow of current as indicated by the arrows in the figure. 
     Another alternative plug design is shown in FIG.  8 . Plug  170  has a generally “P”-shaped design. Heat applied to surface  172  causes free charges in the material to migrate toward the top. Interaction with the electromagnetic field directs the charges around the loop  174  and a continuous flow of current is established. In this design, as well as in the design of FIGS. 7A,  7 B, the current flow within the plugs increases the interaction with the electromagnetic field and thereby increases the torque on the rotor. 
     The quantity of free charges in the plugs may be enhanced by fabricating on the plugs  160  and/or  170  additional layered construction. Using a chemical vapor deposition (CVD) or similar process, plugs  160  and/or  170  may be upgraded with several alternating layers of insulator and doped silicon or other suitable material deposited or attached in rings or bands at the top and/or side cavities of the plugs. Forces of repulsion by and between the mobilized charges in the main body of the plug and the charges in the rings or bands will free the charges in the silicon layers. The electromagnetic field will cause the free charges to flow continuously in each layer around the rings or bands, thereby enhancing the quantity of free charges contained in each plug. 
     FIGS. 9A,  9 B illustrate a further enhancement of the subject invention. The power output of the engine may be increased by applying a pulsed magnetic field using permanent magnets in addition to the pulsed electromagnetic field generated by the electromagnets. This will minimize electricity requirements. An assembly  180  of permanent magnets  182  is arranged around the engine rotor. Assembly  180  comprises a plurality of rods  184 . Each of the rods carries a plurality of rollers  186  on which permanent magnets  182  are mounted. Each of the rods is connected at one end of the engine housing to a drive mechanism  188 , which is driven by motor  190 . Each of the rods is rotated to thereby generate pulsed magnetic fields in the vicinity of each of the rollers. 
     Referring to FIG. 10, an additional enhancement includes an open ended honeycomb-like grid  200 , made from magnetic shielding sheeting material, that is attached to the inside of housing  104 . Each opening of the grid compartmentalizes a single magnet location. The magnetic shield fences and concentrates the magnetic field applied to each zone on the rotor. The shield also protects the rotor zone by minimizing magnetic interference or eddying from/by adjacent zones, thus providing maximum magnetic force field to the charges in each plug. 
     The principle of operation of the subject invention has been tested using a commercially available polysilicon rod. The rod was suspended for rotation about its lengthwise center. Heat was applied to one end of the rod with a candle and a permanent magnet was positioned in proximity to the opposite end of the rod. The rod was observed to rotate away from its equilibrium position. The rod returned to its equilibrium position only if either the magnet or candle were withdrawn. 
     Among the advantageous features of an engine constructed in accordance with the present invention are the following: 
     1. Lightweight and compact. 
     2. Very few internal moving parts. 
     3. Easily adaptable to different sizes/outputs, whereby the total number of plugs determine the engine output. 
     4. Engine working temperature determined by plug material used. 
     5. Solid state design of adding layers of insulation and thermoelectric material on plug enhances number of charges in plug. 
     6. Lower working temperatures compared to other heat cycle engines, e.g. heat discharged from air conditioning unit could be used on engine coupled to blower for energy savings. 
     7. Magnetic shielding around magnets enhances field effect on plugs and engine performance. 
     8. Additional pulsed light introduced between magnets and plugs will enhance output/performance. 
     9. Mechanical energy and electrical power produced in a single unit, rather than having a separate driving unit coupled to a generator. 
     It will be recognized that the above-described invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the disclosure. Thus, it is understood that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.