Cooling system

Information

  • Patent Application
  • 20060156726
  • Publication Number
    20060156726
  • Date Filed
    February 16, 2006
    18 years ago
  • Date Published
    July 20, 2006
    18 years ago
Abstract
A cooling system using a heat differential power system and apparatus for cooling and generating mechanical and/or electrical power in a system are presented. A number of embodiments are presented. In each embodiment a heat differential power system is implemented which dissipates heat created by heat-generating components, such as, but not limited to, microprocessors, within the system and utilizes the heat differential created between the heat generating components and other parts of the system as power to operate the heat differential power system and convert thermal energy into other forms of energy such as, but not limited to, mechanical, and/or electrical energy for powering desired systems such as, but not limited to, fans, or other electrical components, and/or extending the battery life in a portable system.
Description
BACKGROUND OF THE INVENTION
Description of the Related Art

Portable computing and telecommunication devices are increasingly being used. At the heart of these devices are processors and other heat-generating components which are becoming increasingly more powerful and which, as a result, are requiring more power to operate and generating more heat in operation. More sophisticated methods is needed for cooling these heat generating components in these systems as well as heat generating components in a wide variety of other applications and system.


When these devices are used in portable mode, there is an ever increasing demand on the battery for power, which in turn shortens the battery life. Moreover, in portability mode, these devices are often at rest on a person's lap or in close contact with other parts of the body and it is not desirable to have increasing amounts of heat in such close contact with the human body.


An additional environmental problem is that the increasing amounts of heat generated by these heat generating components results in additional amounts of wasted energy.


The additional heat being generated by these heat-generating components has other detrimental effects. For example, it can cause component malfunctions or shut-downs and lower the useful life of the components themselves and the device as a whole.


Heat differential power sources or engines such as the Stirling engine have been known and available for some time. They operate on the principal that thermal energy can be converted to other forms of energy such as mechanical or electrical energy and make use of a difference in temperature between two or more points, areas or locations to make this conversion.


Thus, there is a need in the art for a sophisticated method and apparatus for cooling heat generating components. There is a need in the art for a method and apparatus for reducing the power consumed by these systems, particularly in portability mode. There is a need in the art for a method or apparatus for extending the battery life and thus the operational time of these devices in portability mode. There is a need in the art for a method or apparatus to conserve or utilize wasted thermal energy. There is a need in the art for a method or apparatus used to cool the heat generating components, conserve and utilize the thermal energy and/or to extend the battery life which can be deployed within the small footprint available in the case or housing of a system, such as a laptop computer, standalone computer, cellular telephone, an engine or any system with heat generating components. There is a need in the art for an optimal, cost-effective method and apparatus for cooling heat generating components which allows the heat generating component to operate at the marketed operating capacity, and which is effective in portability mode for the device or system.


SUMMARY OF THE INVENTION

A method and apparatus for cooling one or more heat generating components in a system including a heat differential power system; a hot contact thermally coupling one or more heat generating components to the heat differential power system; and a cold contact for thermally coupling a region of the system cooler than the heat generating components to the heat differential power system. A variety of heat differential power-based cooling systems are implemented.


The cooling system as described above wherein the heat differential power system includes a housing containing a gas and having a surface thermally coupled to the hot contact and having another surface thermally coupled to the cold contact; a first piston disposed within the housing for alternately moving the gas toward the surfaces causing the gas to expand as it nears the surface thermally coupled to the hot contact and to contract as it nears the surface thermally coupled to the cold contact; a second piston disposed within or adjacent to the housing which responds to the alternate expansion and contraction of the gas for powering the first piston; and means coupled to the pistons for receiving the mechanical motion of the second piston and providing the first piston with mechanical motion.


The cooling system as described above wherein the cooling power of the system is increased or decreased by increasing or decreasing, respectively, the surface areas of the housing coupled to the hot contact and the cold contact.


The cooling system as described above having additional surface area means thermally coupled to the surfaces of the housing coupled to the hot contact and/or coupled to the cold contact, said additional surface area means providing additional cooling power to the cooling system.


The cooling system as described above wherein the cooler region of the system is the casing of the system.


The cooling system as described above for powering one or more air flow devices for the system.


The cooling system as described above further including a heat dissipating device coupled to one or more heat-generating components for providing additional cooling of the heat-generating components.


The cooling system as described above for conserving electrical energy in the system.


The cooling system as described above for generating electrical energy in the system.


The cooling system as described above wherein the system is disposed within the casing of the system.


The cooling system as described above wherein the first contact is a thermal spreader for spreading the heat from hot spots of one or more the heat generating components.


A method of cooling heat generating components in a system having a heat differential power system by thermally coupling a heat differential power system to one or more heat generating components and thermally coupling a region of the system cooler than the heat-generating components to the heat differential power system.




BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 displays top, cross-sectional view of a system view of a cooling system disposed in a system housing, such as a data processing system housing, for example, and implemented in accordance with the teachings of the present invention.



FIG. 2 displays a sectional view of a heat differential power system disposed within a system housing and implemented in accordance with the teachings of the present invention.



FIG. 3 displays yet another sectional view of a heat differential power system disposed within a system housing and implemented in accordance with the teachings of the present invention.



FIG. 4 displays yet another sectional view of a heat differential power system disposed within a system housing and implemented in accordance with the teachings of the present invention.



FIG. 5 displays a sectional view of a heat differential power system disposed within a system housing and connected to an air flow device and implemented in accordance with the teachings of the present invention.



FIG. 6 displays a sectional view of a heat differential power system disposed within a system housing having a flywheel with magnets disposed thereon and induction coils disposed in close proximity to the magnets as they rotate for generating electrical power and implemented in accordance with the teachings of the present invention.



FIG. 7 displays a sectional view of a heat differential power system disposed within a system housing having a flywheel with induction coils disposed thereon and magnets disposed in close proximity to the induction coils as they rotate for generating electrical power and implemented in accordance with the teachings of the present invention.




DETAILED DESCRIPTION

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not limit the scope of the invention.


Although the present invention is described herein in the context of cooling heat generating components in a wide range of data processing systems and telecommunication systems, it will be understood that the present invention applies to any system or application for cooling heat generating components. In the present invention, heat produced by a heat generating component, such as a microprocessor, for example, is dissipated by a cooling system which also converts otherwise wasted thermal energy into mechanical and/or electrical power to be used by the system. The present invention may be utilized in any computing, communications, personal convenience applications, engines, industrial systems, mechanical systems, etc. For example, the present invention could be implemented in a variety of personal computers which are portable or stationary, cell phones, and personal digital assistants (PDAs). The present invention is equally applicable to any number of heat-generating components (e.g., central processing units, digital signal processors, lasers, engine parts or any heat generating component that requires cooling) within such systems. For purposes of explanation and illustration, the present invention is hereafter described primarily in reference to a central processing unit (CPU) within a portable personal computer such as a laptop.


Referring now to FIG. 1, a cross-sectional, top view of a data processing system 100 is depicted with a heat generating components 104 and 105 that are cooled by the heat differential power system 200 depicted in FIG. 2. The data processing system 100, shown in part only in FIG. 1, comprises a housing 101 such as a computer cabinet or case, a main circuit board 102 such as a motherboard, heat generating component(s) 104 and 105, such as a microprocessor, which are in direct thermal contact with a heat collector 103. The heat collector 103 is coupled to the heat differential power system in FIG. 2. The heat collector 103 can be made from a variety of materials that have good thermal transfer characteristics, such as copper. In FIG. 1, the heat collector can be a wide variety of shapes and thickness as suited to a particular application. The different configurations would be obvious to one skilled in the art. One embodiment, of the heat collector is a comparatively thin, rectangular piece of copper thermally coupled to the heat generating components 104 and 105 by a thermally conductive means of which a wide variety of metals or compounds are available such as thermal heat sink compound paste.


In operation, heat generated by the heat generating components 104 and 105, is transferred to the heat collector 103 and then on to the heat differential power system 200 where it is used to create the temperature differential to operate the heat differential power system 200 and where heat is dissipated in the process. The heat differential power system 200 is similar to a Stirling engine and uses thermal differentials to operate. This heat differential power system 200 is depicted in FIGS. 2-6. In FIG. 1, the heat differential power system 200 acquires the thermal energy to operate through the heat collector 103.


In FIG. 1, an air-cooled device 106, such as a heat sink, is also depicted. The air cooled device 106 is thermally coupled to heat generating component 105 via the heat collector 103 and provides additional cooling of heat generating component 105. In this example, heat collector 103 also acts as a heat spreader to spread the heat generated by hot spots of the heat generating components 104 and 105. This also enables the cooling device, of which one embodiment is an air cooled device, to do a more efficient job of cooling.


It will be understood that the present invention encompasses embodiments where no air cooled device is used. Thus, if incremental cooling in addition to that provided by the heat collector 103 and the heat differential power system 200 is not needed for one or more of the heat generating components, no air cooled device, including air cooled device 106 would be used. Conversely, if heat generating component 104 required additional cooling, an air cooled device can be added and thermally coupled to heat generating component 104. Additionally, a single air cooled device could be used to provide additional cooling of both heat generating components. Alternatively, if substantial, additional cooling power is required, the heat differential power system 200 itself can be adjusted as will be explained subsequently and used with or without an air cooled device such as air cooled device 106.


It will also be appreciated that the present invention includes a variety of coupling techniques used to thermally couple the heat collector 103 and the air cooled device 106 to the heat generating components. For example, the heat collector 103 may be thermally coupled to a different surface, such as the bottom, of the heat generating components 104 and 105 while the air cooled devices are coupled to top surface of the heat generating component 105. This arrangement would provide cooling to two different surfaces of one or more of the heat generating components further increasing the cooling power of the system 100.



FIG. 2 is a cutaway frontal view of a heat differential power system according to the present invention. The heat differential power system 200 operates when there exists a thermal differential (temperature difference) from one side 201 of the power system 200 to the other side 204. Very small differentials are needed to start and operate the engine. A very precisely made small power system 200 could operate from the heat emitted by one's hands at normal room temperature. As the thermal differentials become greater, the power system 200 produces more power.


The power system 200 includes a sealed housing 215 having a hot side 204A and 204B and a cold side 201. The hot side 204A and 204B are thermally connected to the heat collector 103. The cold side 201 is thermally connected to a cooler region such as the data processing system casing 101, as shown in FIG. 1. It should be noted that the cold side may be thermally connected to other points in the system and the hot side may be connected to other points of the heat generating components so long as there is a temperature differential. It is preferred, however, to have these thermal connections to points where there is sufficient temperature differential to generate the desired power from the heat differential power system 200.


A piston 202 moves back and forth toward the hot side 204A and 204B and cold side 201 of the housing. As the piston moves toward the cold side 201, it displaces a gas inside the housing 215 toward the hot side 204A and 204B which causes the gas to expand. As the piston 202 moves toward the hot side 204A and 204B, it displaces the gas in the housing 215 toward the cold side 201 which cause the gas to contract. The expansion of the gas pushes piston 206 away (or outward) from the housing. The contraction of the gas, on the other hand, creates a vacuum like pulse which pulls piston 206 toward (or inward) the housing 215. It will be understood that a wide variety of gases, including air, and combinations thereof may be used in the housing to optimize the particular application.


Piston 202 is not sealed in the chamber 215, which allows gas to be displaced from the cold side 201 to the hot side 204A and 204B and vice versa.


Piston 206 is sealed in the chamber 205 by a low-friction, precision fit. The chamber 205 should be of an appropriate size and shape to fit the particular application and is shown in the figures as a cylinder. Sealing rings may also be used to seal piston 206 as it moves in the chamber 205. The inward and outward motion of the piston 206 is converted to rotating motion by connecting a rod 207 to a crankshaft disc 210. The crankshaft disc 210 is connected to a crankshaft 209. The crankshaft 209 is connected to a flywheel 212, which rotates and moves a connecting rod 213 in and out. The connecting rod 213 is connected to piston 202 causing it to move alternately toward and away from the hot side 204A and 204B and the cold side 201 in the housing 215. The connections of rod 207 to disc 210 and rod 213 to flywheel 212, respectively, are made so as to insure the correct timing of pistons 206 and 202, respectively. It should be appreciated that other means and other forms of movement can be used to convert the inward and outward movement of piston 206 to mechanical and/or electrical energy and that these other forms are within the scope of the present invention.


The heat collector 103 transfers heat to side 204A&B of housing 215 which creates the hot side. The side 201 of housing 215 may be a plate or other suitable device which is in thermal contact with the casing 101 of the data processing system 100 shown in FIG. 1 and thus form the cold side of the housing 215.


Bearing support 208 is a post or other suitable shape that holds a bearing 211 that supports the rotating crankshaft 209. Bearing block 214 supports and atmospherically seals the connecting rod 213 as it cycles in and out of the housing 215 and drives piston 202 back and forth within the housing 215. It is important to note that connecting rods 207 and 213 during operation will have to bend or flex slightly during each cycle. This flexing can be accomplished by inserting a flexible joint, or by utilizing a sufficiently flexible material to construct connecting rods 207 and 213 as would be obvious to one skilled in the art.


Heat generating component 216 is a microprocessor disposed within the data processing system 100. One or more heat generating components 216 can be thermally connected to the heat collector 103. Heat generated by component(s) 216 is transferred to heat collector 103 and thermally coupled to the hot side 204A and 204B of the housing 215. An optional air cooled device 106 is also shown in FIG. 2 and disposed on the heat collector 103 to provide additional cooling of heat-generating component 216.


In operation, heat transferred from the heat generating component 216 to the heat differential power system 200 via heat collector 103 is dissipated by the heat differential power system 200, thereby cooling heat generating component 216. If substantial, additional cooling power is required, the surface areas of the hot side 204A and 204B of the heat differential power system 200 and the surface area of the cold side 201 of the heat differential power system may be increased. This will result in the dissipation of substantial additional heat from the heat generating component 216. Moreover, further heat dissipation power or cooling power can be achieved by adding fins, channels, ripples or any method or providing additional surface area for heat dissipation to the interior or exterior or any combination there of, of sides 204A, 204B and 201 of housing 215. In FIG. 2, fins 217 are depicted on the interiors of sides 204A, 204B and 201 as an example.



FIG. 3 represents a view of the heat differential power system 200 in FIG. 2 from the flywheel 212 perspective. In FIG. 3, the heat differential power system 200 is shown. Also depicted is the cold side 201 of sealed housing 215; the hot side 204A and 204B of housing 215 and piston 202 for displacing the gas within the housing 215.


In FIG. 3, bearing support 208 is a post or other suitable shape that holds a bearing that supports the crankshaft 209. Flywheel 212 is connected to the crankshaft 209. Connecting rod 213 connects the flywheel 212 to the piston 202, Bearing block 214 supports and atmospherically seals housing 215 as the connecting rod 213 cycles in and out of the chamber 215. It should be appreciated that other means and other forms of movement can be used to convert the inward and outward movement of piston 206 to mechanical and/or electrical energy and that these other forms are within the scope of the present invention.



FIG. 4 is a crankshaft 209 side view of the heat differential power system 200. In FIG. 4, the housing 215, the cold side 201, the hot side 204A and 204B, the piston 202, the bearing support 208, the crankshaft 209, the flywheel 212 are depicted similarly as in FIG. 3. In FIG. 4, piston 206 is also depicted as well as chamber 205 for atmospherically sealing piston 206 and housing 215, and connecting rod 207 for converting the inward and outward motion of piston 206 to rotating motion applied to crankshaft disc 210. It should be appreciated that other means and other forms of movement can be used to convert the inward and outward movement of piston 206 to mechanical and/or electrical energy and that these other forms are within the scope of the present invention.



FIG. 5 depicts yet another view, similar to FIG. 2 of the heat differential power system 200. In FIG. 5, the printed circuit board 102 of FIG. 1 such as the motherboard is depicted with a heat generating component 533 such as a microprocessor, disposed thereon. The heat collector 103 disposed on the component 533 thermally couples heat to the hot side 204A and 204B of the power system housing 215. Also depicted in FIG. 5 is an air flow device 538, such as a fan. Within the air flow device 538, a blade assembly 535 is disposed for circulating air through the system 100, such, as for example, directly over the heat generating component 533 or the heat generating components 104 and 105 and air cooled device 106 depicted in FIG. 1. A rotating connecting rod 536 is connected to the crankshaft 209 of the heat differential power system and also connected to the impeller 535 for rotating the blade assembly within the air flow device 538. It shall be understood that connecting rod 536 may be a separate piece connected to the crankshaft 209 or may be just an extension of the crankshaft 209. It should also be appreciated that, it is within the scope of this invention, that a wide variety of methods can be used to transfer or convert power or energy produced by the heat differential power source, such as, but not limited to, electrical, mechanical, magnetic or other as needed to suite a particular application. Such embodiments would be obvious to one skilled in the art. For example, the flywheel 212 may be modified to include blades and thereby act as an air flow device in addition to its other functions. In this example, connecting rod 536, airflow device 538 and blade assembly 535 may be eliminated or left in the system to provide yet additional air flow if desired. Another example would include modifications to connecting rods 207 and/or 213 such that the movement of these connecting rods in the system creates air flow. It will be appreciated then that current invention may act as both a cooling system and an air flow system and generates its own power (from otherwise wasted thermal energy) to provide air flow and/or power.



FIG. 6 is a flywheel side view of the heat differential power system 200 as shown in FIG. 3. Magnets 650A and 650B are attached to the flywheel 212. Coils 651A and 651B are coils of wire that form a complete circuit, so that electrical flow can enter on one conductor 652A, then pass through a continuous coil of wire 651A and 651B, and then exit on the other conductor 652B in the pair, 652A and 652B depicting wires that form the ends of coils 651A and 652B. The magnets 650 rotate with the flywheel 212. As each magnet travels past the coil of wire 651, a small electrical power pulse is produced. It should be appreciated that multiple magnet and coil arrangements could be placed around any rotating component, and should not be limited to the two as depicted in FIG. 6. Similarly, it should be understood that flywheel 212 need not be used for the magnet 650 and coil 651 assemblies, but that any device connected to the crankshaft 209 can be utilized. It should also be appreciated that, it is within the scope of this invention, that a wide variety of methods can be used to transfer or convert power or energy produced by the heat differential power source, such as, but not limited to, electrical, mechanical, magnetic or other as needed to suite a particular application. Such embodiments would be obvious to one skilled in the art.



FIG. 7 is a flywheel side view of the heat differential power system 200 as shown in FIG. 3. Coils 651A and 651B are attached to the flywheel 212 for movement past stationary magnets 650A and 650B. The flywheel 212 is provided with a commutator surface 659 attached to the crankshaft disc 210 for passing generated electrical power from the rotating coils 651A and 651B, through electrical conductors 652A and 652B to the commutator 659. The electrical energy is then passed through spring loaded brushes 670A and 670B and then exit to an electrical circuit through conductors 658A and 658B. The commutator 659 is attached to the outside diameter of the crankshaft disc 210. It should be appreciated that a wide variety of configurations could be used for the commutator arrangement to suit the particular design criteria. It is even contemplated that the flywheel could be replaced by a linear induction power generator with the magnets and coils arranged for relative linear movement with respect to one another. An advantage of such a linear induction power generator is that it can be inserted into narrower spaces that a flywheel arrangement. It should also be appreciated that a rotating arrangement does not have to be used, and that anywhere on the heat differential power system where a magnet can be arranged to repeatedly pass by a coil, or a coil can be arranged to repeatedly pass by a magnet, electron flow can be induced, as with the rotating arrangement to create electrical energy.


The arrangements of FIG. 6 and FIG. 7 can be utilized to reclaim a small amount of electrical energy from the heat differential power system 200 when the power system 200 is running at high speed. This reclamation and conversion of power is highly desirable in portable battery-operated systems to extend the time of operation of the portable system. Similarly, the electrical power generated by this arrangement could be used to help power one or more mechanical devices such as fans for additional cooling. It should also be appreciated that like most power generating units with the proper placement of magnets and coils, the arrangements in FIGS. 6 and FIG. 7 of the coils 651A and 651B in combination with the magnets 650A and 650B could act as a motor to rotate the flywheel. It should be appreciated that this same configuration can be used as a brake to slow, hold, or stop the rotation of the flywheel if desired for a specific purpose.


The present invention reduces the amount of electrical energy required to operate the system 100 by keeping the heat generating components cooler. It also conserves energy by transforming otherwise wasted thermal energy into mechanical and/or electrical energy. The present invention also minimizes medical concerns of overly hot portable devices in contact with the operators.


Thus, the present invention has been described herein with reference to a particular embodiment for a particular application. Those having ordinary skill in the art and access to the present teachings will recognize additional modifications, applications, and embodiments within the scope thereof.


It is, therefore, intended by the appended claims to cover any and all such applications, modifications, and embodiments within the scope of the present invention.

Claims
  • 1. A cooling system for cooling heat-generating components in a system comprising: a heat differential power system; a hot contact means thermally coupling one or more heat-generating components to the heat differential power system; and a cold contact means for thermally coupling a region of the system cooler than the heat-generating components to the heat differential power system.
  • 2. The system as set forth in claim 1 wherein the heat differential power system comprises: a housing containing a gas and having a surface thermally coupled to the hot contact means and having another surface thermally coupled to the cold contact means; a first piston disposed within the housing for alternately moving the gas toward the surfaces causing the gas to expand as it nears the surface thermally coupled to the hot contact means and to contract as it nears the surface thermally coupled to the cold contact means; a second piston disposed within or adjacent to the housing which responds to the alternate expansion and contraction of the gas for powering the first piston; and means coupled to the pistons for receiving the mechanical motion of the second piston and providing the first piston with mechanical motion.
  • 3. The cooling system of claim 2 wherein the cooling power of the system is increased or decreased by increasing or decreasing, respectively, the surface areas of the housing coupled to the hot contact means and the cold contact means.
  • 4. The cooling system of claim 2 further comprising additional surface area means thermally coupled to the interior surfaces of the housing coupled to the hot contact means and/or coupled to the cold contact means, said additional surface area means providing additional cooling power to the cooling system.
  • 5. The system as set forth in claim 1 wherein the cooler region of the system is the casing of the system.
  • 6. The cooling system as set forth in claim 1 for powering one or more air flow devices for the system.
  • 7. The cooling system of claim 1 further comprising a heat dissipating device coupled to one or more heat-generating components for providing additional cooling of the heat-generating components.
  • 8. The cooling system of claim 1 for conserving electrical energy in the system.
  • 9. The cooling system of claim 1 for generating electrical energy in the system.
  • 10. The system as set forth in claim 1 wherein the system is disposed within the casing of the system.
  • 11. The system of claim 1 wherein the first contact means is a thermal spreader for spreading the heat from hot spots of one or more heat-generating components.
  • 12. A portable system having one or more cooling systems as set forth in claim 1.
  • 13. A data processing system having one or more cooling systems as set forth in claim 1.
  • 14. A telecommunications system having one or more cooling systems as set forth in claim 1.
  • 15. A method of cooling one or more heat-generating components in a system having a heat differential power system comprising the steps of; thermally coupling a heat differential power system to one or more heat-generating components; and thermally coupling a region of the system cooler than the heat-generating components to the heat differential power system.
  • 16. The method as set forth in claim 15 wherein the heat differential power system includes a housing containing a gas and having a surface thermally coupled to the heat-generating components and having another surface thermally coupled to the cooler region, the method further comprising the steps of; alternately moving the gas toward the surfaces by means of a first piston causing the gas to expand as it nears the surface thermally coupled to the heat generating-components and to contract as it nears the surface thermally coupled to the cooler region; responding to the alternate expansion and contraction of the gas by means of a second piston disposed within or adjacent to the housing for powering the first piston; and coupling the first and second pistons such that the mechanical motion of the second piston provides the first piston with mechanical motion.
  • 17. The method as set forth in claim 16 for providing additional cooling power by increasing the surface areas of or coupled to the surface of the housing coupled to the heat generating-components and/or the surface of the housing coupled to the cooler region.
  • 18. The method as set forth in claim 15 for conserving electrical energy in a system
  • 19. The method as set forth in claim 15 for powering an air flow device.
  • 20. The method as set forth in claim 15 for generating electrical energy in a system.
  • 21. The cooling system as set forth in claim 1 which generates mechanical and/or electrical power.
  • 22. A cooling system for cooling heat-generating components having a heat differential power system which generates air flow.
CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation-in-Part application of U.S. patent applications Ser. No. 11/017,024 filed on Dec. 20, 2004 entitled “Heat Differential Power System” and U.S. patent application Ser. No. 11/240,863 filed Sep. 30, 2005 and also entitled “Heat Differential Power System”.

Continuation in Parts (2)
Number Date Country
Parent 11017024 Dec 2004 US
Child 11354807 Feb 2006 US
Parent 11240863 Oct 2005 US
Child 11354807 Feb 2006 US