US20030110779A1

US20030110779A1 - Apparatus and method for augmented cooling of computers

Info

Publication number: US20030110779A1
Application number: US10/017,710
Authority: US
Inventors: Robert Otey; Brian Rabe
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-12-14
Filing date: 2001-12-14
Publication date: 2003-06-19
Also published as: AU2002364002A1; WO2003052819A2; WO2003052819A3; AU2002364002A8

Abstract

A combination of a computer and an external heat transfer module to improve the heat removing capability of a computer's internal heat removal system, the combination includes a computer with a thermal interface port connected to the computer's internal heat removal system and a heat transfer module connected to the thermal interface port. The heat transfer module has a heat dissipation component and at least one heat transfer conduit having one end thermally coupled to the computer's internal heat removal system, and the other end thermally coupled to the heat dissipation component.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of heat removal from electronic components. More particularly, the present invention relates to the removal of heat from an integrated circuit.

2. Description of the Prior Art

Improved processing technology and higher levels of integration produce increasingly complex integrated circuits. These new generations of integrated circuits often operate at higher frequencies and generate more heat than their predecessors.

In device thermal management, as in the electrical design, the limitations to performance are relatively straightforward. Maintaining electronic devices at acceptable temperature levels requires that the heat they generate be transferred to the surrounding air by a combination of conduction, natural and/or force convection, and radiation. In typical electronic operating temperature ranges, the effect of radiation is less significant. Hence, a combination of conduction, natural or forced convection becomes the primary means of heat removal.

In natural and forced convection heat sink applications, the heat sink surface area and air velocity are the controlling parameters for the heat sink's power dissipation capacity. When heat sink surface area and air velocity are at a minimum, power dissipation capacity is at a minimum. Conversely, when area and air velocity are maximized, power dissipation capacity is maximized. To provide a high performance heat sink either surface area or air velocity or both must be maximized.

Thermal solutions can be divided into two categories. One is referred to as passive solutions like heat sinks, heat pipes and metal plates since there is no need of external power to drive the cooling system to function. The other is called active solutions like fans and fan-heat sinks where external power is needed for the cooling system.

Typically, heat sinks, fans and heat pipes are employed to dissipate heat from integrated circuits and other electronic components. Increases in heat generation are often accommodated by simply increasing the quantity or size of these heat dissipation elements. Specifically, heat sinks with greater heat dissipation capacity are generally larger, heavier, or require more airflow. Similarly, fans added to cool components occupy space, produce noise, and provide a potential for failure. Maintaining circuit temperatures at an appropriate level is a serious technical problem in ensuring peak performance and reliability of computers.

Meanwhile, computers have a tendency to decrease in size to enhance value, portability and convenience. Dealing successfully with the contradictory problems of removing heat and reducing size is a key in developing the next generation of medium and small-sized computers.

Most of the more recent designs incorporate a heat sink/fan/vent and some use an internal heat pipe. In one design, a heat pipe is used to transport the heat from the processor to a remote heat exchanger. A small fan blows air over the remote heat exchanger and dissipates the heat to the ambient air outside the computer chassis.

Examples of some thermal management systems are as follows. U.S. Pat. No. 5,339,214 (1994, Nelson) discloses a computer chassis assembly that includes a heat pipe which thermally couples an electronic package to multiple fan units. The heat pipe provides a computer chassis that sufficiently cools internal heat generating components without placing the components in close proximity to the fans.

U.S. Pat. No. 5,383,340 (1995, Larson et al.) discloses a two-phase cooling system for a portable computer which in one embodiment consists of an evaporator which is positioned within the base of the computer and a condenser which is positioned within or attached to the lid of the computer. The evaporator and condenser are connected by flexible tubing. The tubing may run externally from the lid to the base or it may extend through one or more of the hinges that connect the base and the lid. In an alternative embodiment, both the evaporator and the condenser of the two-phase system are incorporated into either the base or the lid of the computer.

U.S. Pat. No. 5,513,070 (1996, Xie et al.) discloses an improved heat dissipation device particularly suited for removing heat from a surface mounted integrated circuit component coupled to a printed circuit board in a portable computer. Vias, which are at least partially filled with a heat conductive material, improve heat transfer between a component and a heat conductive block mounted on opposite surfaces of the circuit board. A first section near one end of the heat pipe is attached to the heat conductive block in a channel formed receptive to the heat pipe. A second section of the heat pipe including the second end is attached to a metal plate that is affixed beneath the keyboard. Heat from the component flows through the vias to the block and is transferred by the heat pipe to the metal plate where it is dissipated.

Despite these advancements, heat transfer is even more of a problem with laptop and notebook computers. Today's laptop and notebook computers are performance limited not by electronic power density or computing power, but instead by the heat associated with increased power density and advanced computing power. Additionally, today's performance potential has led to power constraints associated with battery capacity including large capacity designs such as Lithium Ion. While electronic packaging and performance advances have reached a point where notebooks could achieve performance levels equivalent to today's personal desktop units, the heat and power constraints have provided a barrier, which limits their performance.

To solve the power limit issue, the industry has adopted dual performance modes for the laptop computer. The first mode is battery/DC mode where the computer runs at reduced processor and video performance along with special storage device operations to conserve power. The second mode is AC mode where the system runs at full design capacity and performance. This level of performance being limited by heat removal from the computer. The desktop solution, as previously mentioned, includes multiple fans, specially designed heat sinks, and even built-in mechanical refrigeration devices. The size, weight, and power constraints have limited the application of this technology in laptop and notebook computers. This separation or difference in performance prevents power users from using just one device, i.e. laptop or notebook, for all their needs.

In addition, there is and always has been a segment of the computing public that attempts to push current microprocessors beyond their rated limits. This is generally achieved by a procedure called “over-clocking” a microprocessor. Inside all PCs, the system clock sets the pace for the speed of the computer. When computer manufacturers build a system, they assemble components that are known to operate at a predetermined speed. The speed of the bus on the motherboard in a computer tells the processor how fast to execute instructions. Bus speed is controlled by a clock setting on the motherboard. By simply changing a jumper or two on the motherboard, the speed increases.

Many motherboards are designed to accept several speeds of processors. Manually changing the clock speed and voltage to a microprocessor produces performance outside the chip design. This is called by those skilled in the art as “over-clocking” the processor. Increasing the clock speed causes the components to run faster. However, increasing the frequency causes the components to run hotter. Experts agree that over-clocking shortens the life of the processor chip because is runs at a higher temperature caused by the over-clocking than for which the processor was designed. The standard cooling systems used in computers today are insufficient to cool an “over-clocked” microprocessor to a level sufficient to prevent heat damage to the microprocessor.

Therefore, what is needed is a heat transfer module that is capable of increasing the heat removal capability of standard cooling systems used in computers. What is further needed is a heat transfer module whose characteristics allow electronic components to operate at cooler temperatures when powered at high performance levels. What is still further needed is a heat transfer module that is adapted for connection to internal thermal management systems of computers ranging in size from laptop to desktop computers.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a heat transfer module that connects to the internal thermal management system of a computer to increase heat removal from operating electronic components. It is a further object of the present invention to provide a heat transfer module that augments the internal thermal management system of a computer to allow electronic components to operate at cooler working temperatures thus increasing reliability and life expectancy of the electronic components. It is another object of the present invention to provide a heat transfer module that augments the internal thermal management system of a computer such that the electronic components can be operated at higher performance levels while maintaining the operational temperature of the electronic component below the maximum recommended component temperature specification. It is still another object of the present invention to provide a heat transfer module that augments the internal thermal management system of a computer by connecting the heat transfer module to a thermal interface port on the computer. It is yet another object of the present invention to provide a computer docking station that incorporates a heat transfer module that connects to and augments the internal thermal management system of a laptop computer.

The present invention achieves these and other objectives by providing an external heat transfer module having an interface coupling that connects to a thermal interface port of a computer for augmenting the heat removal system of the internal, thermal management system of the computer. One embodiment of such a heat transfer module is one that includes a thermoelectric device, a heat conductive plate in thermal contact with a cool side of the thermoelectric device, and at least one heat transfer medium having a first portion adjacent to one end of the medium and adapted for coupling to a computer's heat removal system and a second portion adjacent to the other end of the medium and in thermal contact with the heat conductive plate. The heat transfer medium may be a solid, thermally conductive rod or a heat pipe that employs a two-phase system. Another embodiment of such a heat transfer module is one that includes a high-end, thermally conductive heat sink coupled to a fan and to the heat transfer medium, which is adapted for coupling to a thermal interface port of a computer.

The efficiency of prior-art heat removal systems is limited to the ability of those systems to dissipate and transfer heat to the surroundings. Even in so-called “optimized” systems that use fans, heat sinks and heat pipes, the temperature difference between the ambient air and the heat sink will limit the systems heat removal efficiency. The higher the ambient air temperature, the less heat that can be dissipated and, thus, the less heat throughput available. The essence of the present invention is the coupling of a computer's internal heat management system with an external heat removal module through a thermal interface port.

The present invention has a thermoelectric device that is in thermal contact on its cool side with a heat conductive plate and on its hot side with a heat sink. Typically, the heat sink is coupled to a fan to aid in dissipating the heat from the thermoelectric's hot side. The thermally conductive plate has attached thereto a heat transfer medium such as a metal rod or a heat pipe. The heat transfer medium has a connector at its opposite end designed to mate with a thermal interface port connected to the heat dissipating unit of a computer's thermal management system. As is well known, power is supplied to the thermoelectric device to create the hot and cool side of the thermoelectric device. To enhance the thermal conductance between the hot and cool side of the thermoelectric device with the heat sink and heat conductive plate, respectively, a thermally conductive paste or other thermal interface material is used at their interfaces.

For laptops and notebooks in particular, this heat removal system would provide the capability of installing faster, high performance processors and video cards without raising internal temperatures, or provide a cooler environment for existing configurations that will improve performance and reliability. In a docking station configuration combined with the multi-mode operation of the laptop or notebook computer, the present invention will enable laptop or notebook computer full operating potential. As currently designed, the computer will limit performance and power draw when removed from the docking station. The incorporation of the present invention will enable the power user to perform all required tasks on a single computer by providing both power and portability while eliminating the need to carry back-up data on separate media, or performing lengthy data synchronization operations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the heat transfer module of the present invention. [0024]
FIG. 2 is an enlarged, cross-sectional view of the present invention showing the thermoelectric element, the heat conductive plate, the heat transfer medium, and the heat sink. [0025]
FIG. 3 is an enlarged, perspective view of three embodiments of thermal connectors for connecting the present invention to a computer's thermal management system. [0026]
FIG. 4 is a perspective view of a docking station for a portable computer incorporating the heat transfer module.[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the present invention is illustrated in FIGS. 14. FIG. 1 illustrates a [0028] heat transfer module 10 having a thermoelectric device (not shown), heat receiving portion 20, and a heat dissipation portion 40. Heat receiving portion 20 includes a heat conductive plate 22 and a first end 31 of a heat transfer conduit or heat pipe 30. Heat dissipation portion 40 has a heat sink 42 and a fan 46. Fan 46 is typical of the fans used in computers.
Heat [0029] conductive plate 22 is typically a copper plate having a thickness in the range of about {fraction (1/32)} inch (0.79 mm) to ⅛ inch (3.18 mm). Heat pipe 30 is typical of those commonly used in heat transfer, generally having a diameter between 2 to 8 mm. A first portion 32 of heat pipe 30 is preferably flattened to create an oblong shape having a flat portion for soldering to one side of heat conductive plate 22 and to enhance heat transfer. It is noted that, even though first portion 32 is deformed, it maintains enough of its structure to function as a heat pipe. This configuration provides for a thinner profile of the heat receiving portion 20 than would be achieved with a heat conductive plate 22 having a thickness sufficient to form a semi-circular groove for receiving a portion of a cylindrical heat pipe or have a bore hole sized to receive a heat pipe. In the groove configuration, it is typical to place the heat pipe in a pair of coupling grooves in the conforming surfaces between two, heat transfer plates. It should be understood that these latter configurations, though not shown, are also within the scope of the present invention.
Turning now to FIG. 2, [0030] thermoelectric device 12 is sandwiched between heat receiving portion 20 and heat sink 42. Thermoelectric device 12 has a matrix of thermoelectric elements 14 electrically connected between a pair of electrically insulating substrates 13. Thermoelectric device 12 also includes a pair of electrically conductive, insulated wires 15 electrically coupled to the matrix of thermoelectric elements 14 to provide voltage to device 12. When power is supplied to thermoelectric device 12, one of the electrically insulting substrates 13 becomes cool while the other substrate 13 becomes hot. This is caused by the Peltier effect, which occurs in the thermoelectric elements 14. A typical thermoelectric device requires DC power in order to produce a net current flow through the thermoelectric elements in one direction. The direction of the current flow determines the direction of heat transfer across the thermoelectric elements.
[0031] Heat sink 42 has a base portion 43 formed as a planar sheet and a fin portion 44. Although a thermally conductive epoxy or other adhesive methods are acceptable in bonding the outer planar surfaces of thermoelectric device 12 to heat dissipating portion 40 and heat conductive portion 30, a compression mounting method such as using screws or the like passing through openings at the four corners of heat plate 22 and into threaded recesses in base portion 43 of heat sink 42 is preferred in larger thermoelectric applications.
Another embodiment (not shown) includes a heat transfer module that has a high-end, thermally conductive heat sink coupled to a fan and to the heat transfer medium or conduit, which is adapted for coupling to a thermal interface port of a computer. [0032]
FIGS. [0033] 3A-3C show three embodiments of a second end of heat pipe 30. Turning first to FIG. 3A, there is shown a heat pipe coupling system 50. Heat pipe coupling system 50 includes heat module coupling end 52 and a thermal management system end 56. Heat module coupling end 52 includes a flattened portion 54 of heat pipe 30 soldered to a heat transfer board 55. Thermal management system end 56 includes a heat transfer base 57 and a pair of biasing springs 58 connected at or near one end of heat transfer base 57. Thermal management system end 56 is sized to receive heat module coupling end 52 and hold heat transfer board 55 in thermally conductive contact with heat transfer base 57. Thermal management system end 56 is preferably secured to the heat dissipation end of a computer's thermal management system such as the remote heat exchanger. It should be understood by those skilled in the art that the terms used to describe the heat pipe coupling system 50 is not restrictive of which end 52 or 56 is part of the heat transfer module 10 or the thermal management system of the computer. These are interchangeable, depending on design and manufacturing parameters used for a thermal interface port.
FIG. 3B shows another embodiment of a useable thermal connection. [0034] Thermal connection 60 includes receiving prongs 61 thermally mounted to second end of heat pipe 30. Receiving prongs 61 are sized and configured to receive an end portion 63 of a heat pipe 62 in a friction fit, much like that of a phone plug and jack. End portion 63 is typically connected to the heat dissipation end such as a remote heat exchanger of a computer's thermal management system.
FIG. 3C shows yet another embodiment of a usable thermal connection. [0035] Thermal connection 70 includes a flattened portion 72 of heat pipe 30. Receiving portion 74 includes a spring-loaded, elongated, flat portion 76 contained within an elongated receiving housing 78. Receiving portion 74 is sized to receive flattened portion 72 such that flattened portion 72 is in intimate, thermal contact with springloaded flat portion 76.
It is noted that the three embodiments for a thermal connection to be used as a thermal interface between the external [0036] heat transfer module 10 and the computer's internal heat management system are not limiting. It will occur to those skilled in the art that other embodiments of a thermal interface may be used for defining a thermal interface port. It is the combination of an external heat transfer module coupled through a thermal interface port to a computer's internal heat management system that is considered novel, and that the scope of the present invention is not limited to the detailed embodiments described herein.
FIG. 4 shows one embodiment of a [0037] docking station 80 for a notebook-type computer 100. Docking station 80 includes as many interface connections 81 as required for a particular brand and model of notebook/portable computer. Also included in docking station 80 is a heat transfer module 82 of the present invention with an appropriate thermal interface port or connection 84 to computer 100. The ability to augment the thermal management system of notebook computers allows one to perform all required tasks on a single computer. This is achieved by providing both power and portability while eliminating the need to carry back-up data on separate media, or performing lengthy data synchronization operations.
Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims. [0038]

Claims

What is claimed is:

1. An external heat transfer module to improve the heat removing capability of a computer's internal heat removal system, said module comprising:

a thermoelectric device;

a heat conductive plate in thermal contact with a cool side of said thermoelectric device; and

at least one heat transfer conduit having a first portion adjacent to one end of said at least one heat transfer conduit and thermally coupled to said computer's internal heat removal system, and a second portion adjacent the other end of said at least one heat transfer conduit, said second portion thermally coupled to said heat conductive plate.

2. The module of claim 1 wherein said heat transfer conduit is a heat pipe.

3. The module of claim 1 further comprising a heat sink thermally connected to a hot side of said thermoelectric device.

4. The module of claim 1 further comprising a fan for moving air over said hot side of said thermoelectric device.

5. The module of claim 1 wherein said second portion of said heat transfer conduit has a flattened shape.

6. An external heat transfer module for improving the heat removing capability of a computer's internal heat removal system, said module comprising:

thermoelectric means having a hot side and a cold side; and

heat transfer means thermally coupled to said cold side of said thermoelectric means for transferring heat from said computer's heat removal system to said thermoelectric means.

7. The module of claim 6 wherein said thermoelectric means includes a heat dissipation means for dissipating heat from a hot side of said thermoelectric means.

8. The module of claim 6 wherein said heat transfer means includes a heat plate means thermally connected to a heat conduit means.

9. The module of claim 7 wherein said heat dissipation means is a heat sink.

10. The module of claim 9 wherein said heat dissipation means further includes a fan.

11. The module of claim 8 wherein said heat conduit means is a heat pipe.

12. In combination a computer and an external heat transfer module, said combination comprising:

a computer with a thermal interface port connected to the computer's internal heat removal system; and

a heat transfer module external to said computer, said heat transfer module connected to said thermal interface port of said computer.

13. The combination of claim 12 wherein said heat transfer module includes a heat dissipation component and at least one heat transfer conduit having a first end thermally coupled to said heat dissipation component, and a second end connected to said thermal interface port.

14. The combination of claim 13 wherein said heat dissipation component includes a thermoelectric device wherein a cool side of said thermoelectric device is coupled to said first end of said at least one heat transfer conduit.

15. The combination of claim 14 wherein said heat dissipation component further includes a thermal conductive plate in thermal contact with said cool side of said thermoelectric device.

16. The combination of claim 13 wherein said at least one heat transfer conduit is a heat pipe.

17. A docking station for a laptop computer comprising:

an enclosure;

a laptop computer interface on at least one side of said enclosure wherein said interface has at least a thermal interface port; and

a heat transfer module within said enclosure and coupled to said thermal interface port, said heat transfer module comprising:

a heat dissipating device; and

at least one heat transfer conduit having a first portion adjacent one end of said at least one heat transfer conduit thermally connected to said heat dissipating device, and a second portion adjacent the other end of said at least one heat transfer conduit, said second portion being thermally connected to said thermal interface port.

18. The docking station of claim 17 wherein said heat dissipating device is a thermoelectric device wherein a cool side of said thermoelectric device is thermally connected to said heat transfer conduit.

19. The docking station of claim 18 wherein said heat dissipating device further includes a thermal conductive plate thermally coupled to said cool side of said thermoelectric device and said heat transfer conduit.

20. The docking station of claim 19 wherein said thermoelectric device further includes a heat sink thermally coupled to said second substrate.

21. The docking station of claim 20 wherein said thermoelectric device further includes a fan coupled to said heat sink for moving air over said heat sink.

22. The docking station of claim 17 wherein said heat transfer conduit is a heat pipe.

23. A method of making an external device for improving the heat removing capability of a computer's internal heat management system, said method comprising:

attaching a first portion of one end of a heat transfer conduit to a heat dissipating device; and

configuring a second portion of the other end of said heat transfer conduit for thermally mating with a heat dissipation end of said computer's internal heat management system.

24. The method of claim 23 wherein said heat dissipating device is a thermoelectric device wherein a cool side of said thermoelectric device is thermally coupled to said heat transfer conduit.

25. The method of claim 24 further comprising thermally coupling a heat conductive plate to said cool side of said thermoelectric device.

26. The method of claim 25 further comprising thermally coupling a heat sink to a hot side of said thermoelectric device.

27. The method of claim 26 further comprising coupling a fan to said heat sink for moving air over said heat sink.

28. A method of improving the heat removing capability of a computers internal heat removal system, said method comprising:

obtaining a heat transfer module having one end of a heat transfer conduit thermally coupled to said heat transfer module and the other end of said heat transfer conduit configured for mating to a thermal interface port of a computer, said thermal interface port thermally coupled to said computer's internal heat removal system;

thermally connecting said other end of said heat transfer conduit to said thermal interface port; and

enabling said heat transfer module.

29. The method of claim 28 wherein said heat transfer module is a thermoelectric device wherein a cool side of said thermoelectric device is connected to said heat transfer conduit.