US20080028767A1

US20080028767A1 - Computer cooler

Info

Publication number: US20080028767A1
Application number: US11/461,686
Authority: US
Inventors: Lionel H. Broderick
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-08-01
Filing date: 2006-08-01
Publication date: 2008-02-07

Abstract

The invention is a solid-state thermoelectric cooling device for attachment to a personal or laptop computer. The device consists of a plurality of thermoelectric coolers that are mounted on a heat exchanger, each powered by less than about 12 volts DC, which provides a cold face on a thermoelectric cooling panel which is mounted on the top or a side of the computer. The internal temperature of the computer is controlled to avoid moisture condensation.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to cooling electronic devices and, in particular, to using thermoelectric devices to cool microprocessors, graphics processors, and other computer components.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
In recent years, devices and integrated circuits used in information processing apparati, such as personal computers and servers, tend to generate an increasing amount of heat because of their ever-increasing integration. CPUs increase the amount of heat produced because of their faster operation frequencies and enhanced integration.
Conventional personal computers and servers commonly employ a method of attaching a heat sink to the CPU to transfer the heat of the CPU to the heat sink and cooling the heat sink. To dissipate heat to the outside of the computer, a cooling fan may provide forced air cooling.
The cooling capacity is enhanced by enlarging the heat sink and increasing the airflow of the cooling fan. The enlarged heat sink leads to an increase in the size of the computer while the increased airflow of the cooling fan also results in a size increase of the computer due to the enlarged cooling fan. Airflow may be increased by increasing the speed of the fan, although this tends to increase fan noise.
Radiating heat generated by a CPU or the like that replace the heat sink include a heat pipe and a liquid-cooling system that transport heat by a coolant. These methods feature an increased degree of freedom in the structure because the coolant is cooled at a location remote from a heat-generating source such as CPU. In a case where a cooling fan is used to radiate the coolant-carried heat outside the equipment problems similar to those described above arise.
Various methods have been proposed as solution for these problems. It is known to use air cooling and liquid cooling. However, these techniques are complex or noisy.

BRIEF SUMMARY OF THE INVENTION

A cooling panel that attachable to a personal computer case; where the cooling panel is comprised of a number of solid-state thermoelectric coolers. The thermoelectric coolers are powered by less than about 12 volts of direct current. The thermoelectric coolers are attached to insulated wires which are connected in parallel; and the thermoelectric coolers are mounted on a heat exchanger to facilitate thermal conductance from the case.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a perspective view of the personal computer showing the cooling panels.

FIG. 2 schematically depicts an array of the thermoelectric coolers wired in parallel.

FIG. 3 depicts a single thermoelectric cooler between hot and cold side plates.

FIG. 4 depicts a thermoelectric heat pump module with heatsink.

FIG. 5 presents the steps to cool a computer with a thermoelectric cooling panel.

DETAILED DESCRIPTION OF THE INVENTION

A cold plate cooling device that employs solid-state electronics, also called a thermoelectric cooling panel, has been developed that is adaptable to personal and laptop computer cases to cool the internal components without the noise of fans or pumps and without moving fluid, such as active cooling where water, for example, may leak from the cooling circuits. FIG. 1 presents a personal computer with cooling 2. The cooling panels 14, 16 of FIG. 1, comprise a plurality of thermoelectric coolers 40, as presented in FIG. 3, that are conductively mounted, preferably with Arctic Silver Thermal adhesive, on a thermally conductive plate that is adapted to mount on a computer panel, preferably a side 4 or top 10, for example, of a personal computer case that has a bottom 12, front 6, two sides 4, and a back 8. The solid-state electronics are essentially bimetallic thermocouples that are powered with DC power to create a Peltier junction cooling effect.
The personal computer of FIG. 1 also presents an air intake hole 18 that may optionally be employed as well as an air exhaust hole 20 which may be employed with an internally mounted fan to force air to flow through the case as a supplement to utilization of the cold plate cooling device 14, 16. It is also conceived that in alternative embodiments, an internal fan may be employed to direct cooled air to specific hot components, such as a central processing unit chip. Generally it is preferred that the personal computer case be sealed to prevent air flow into or from the interior of the case, thereby retaining the cooled air inside the case, as well as minimizing the supply of moisture laden air to the inside of the case, which may then condense if the temperature of the cooled air or computer components inside the personal computer case are below the dew point. It is preferred that the minimum cooled temperature be maintained above the dew point, which is accomplished by an optional humidity sensor in a temperature control circuit.
Also presented in FIG. 1 is a direct current power supply 22 that is connected to each of the thermoelectric cooling panels 14, 16 by power supply leads 24. Each power supply lead contains both a positive and a negative lead to supply dc power to the cooling devices 14, 16.
The thermoelectric coolers 40, FIG. 3, are solid state heat pumps. Heat is “pumped” from the cold surface 42 to the hot surface 44 when a DC current is applied to the device 40. A heat sink 56, FIG. 4, is required on the hot surface 44 to effectively remove the heat pumped from the cold surface 42. A no-load temperature differential of up to 65° C. with efficient heat removal is obtainable. The two greatest concerns for reliability are overheating and breakage. The junction surface is of a ceramic material which is easily broken. Heat generated by the pumping action is removed with a heat sink 56. The modules will preferably operate with voltages from 3 to 12 volts. At higher voltages, with the increase in current, the thermoelectric cooling panel 14, 16 must be appropriately sized.
The thermoelectric heat pump module with heatsink 54 is generally illustrated in FIG. 4. The high thermal conductivity cold plate 58 is selected from the group of thermally conductive materials, including copper, aluminum, brass, stainless steel, beryllium, and titanium, and is preferably ⅛-inch thick copper or ¼-inch thick aluminum, and most preferably aluminum because of its cost, lightweight and resulting advantage in handling and mounting. In a preferred embodiment, both sides of the conductivity junction are coated with a thin layer of a heat sink compound (not illustrated) to facilitate thermal transfer.
Electrically insulated power leads 46 supply DC current to the thermoelectric heat pump module with heatsink 54. The cold plate 58 is placed toward or against the computer to conduct heat from the hot computer through the cooling device to the heatsink 56 and then to the surrounding environment, generally ambient or cooled air.
The thermoelectric cooler 40 is presented in the assembly 54 of FIG. 4 as cooler assembly 60. The cold plate 58 is fixedly mounted to the heat exchanger 56 by means of thermally insulated standoffs 52, which are preferably nylon hardware, but which in an alternative embodiment may be standoffs that are thermally insulated with insulating washers. To increase thermal exchange efficiency and to prevent moisture condensation on the cold surface 42 or on other cold parts of the thermoelectric heat pump 54, a vapor barrier 50 is applied which is preferably an RTV silicone sealant.
Illustrated in FIG. 2 is a thermoelectric heat pump module 54 placement and wiring presentation generally 30, that illustrates thermoelectric cooler 32 placement for a 4 by 7 rectangular matrix. It is known by the inventor that the arrangement of modules 54 need not be rectangular, square or any regular geometric pattern and that this arrangement is illustrative only of a parallel wiring diagram where seven coolers 32 are on presented in each row. While it is known that the coolers 32 may be wired partially in parallel or series, it is preferred that each cooler 32 be independently wired in parallel and be powered by a DC power supply by an electrically conductive, insulated positive side wire connector 34 and a negative side wire connector 36.
The thermoelectric cooling panel 14, FIG. 1, is preferably designed as a retro-fit to attach to the side of a personal computer or to the bottom side of a laptop computer. The attachment to the side is preferably achieved with bolts, although in an alternate embodiment attachment is achieved by means of Arctic Silver 5 Thermal Adhesive, from Arctic Silver Inc, Visalia, Calif., a silicone gasket plus a thermally conductive epoxy is employed. Arctic Silver is a preferred conductive epoxy. The cold side of the thermoelectric cooling panel 14 is spaced about ⅛-inch to ⅜-inch from the side 4 of the computer to create a space between the cold sink and the side of the computer 4. It is beneficial that the panel 14 be as intimately and as closely mounted to the side 4 as possible to achieve efficient thermal transfer from the case. The computer case is sealed with a silicone to close all potential air leaks. In an alternative embodiment, the entire side of the computer is replaced with a cooling panel 14.
It has been found that thermoelectric heat pump modules from Mean Well, model SP-300-12, work well at 12 volts or less.
The method steps to cool a computer with a thermoelectric cooling panel are presented in FIG. 5.
In step 1 a computer having a case is provided for cooling. A thermoelectric cooling panel is selected that will fit to at least one side of the computer case. In step 2, the thermoelectric cooling panel is powered by a DC power source and consists of a plurality of solid-state thermoelectric coolers that are wired in parallel.
In step 3 the thermoelectric cooling panel is attached to the computer case with a thermally conductive epoxy, preferably Arctic Silver Thermal adhesive, to assure good thermal conductivity of heat from the case and through the thermoelectric panel to the heat sink and then to the ambient outside environment.
The computer case is sealed in step 4 to prevent cooling loss via air leakage from or into the case. In step 5 the ambient and dew point temperatures inside the computer case are monitored. The temperature of the thermoelectric cooling panel is maintained above the dew point temperature inside the case to prevent moisture condensation inside the case, step 6.
Lastly, in step 7, the computer is turned off, if the ambient temperature exceeds a set point value thereby avoiding damage to the internal components of the computer.
Thus, in accordance with this invention, it is now possible to maintain a computer at a desired operating temperature using solid-state electronics without active cooling, such as air or fluid exchange. This is surprising since known cooling techniques rely on forced air or flowing water to cool the computer components.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims

1. A structure, comprising:

a cooling panel that is adaptable to attach to a personal computer case;

said cooling panel comprised of a plurality of solid-state thermoelectric coolers;

said thermoelectric coolers powered by less than about 12 volts of direct current;

said thermoelectric coolers attached to insulated wires which are connected in parallel; and

said thermoelectric coolers mounted on a heat exchanger.

2. The structure according to claim 1, wherein said heat exchanger is comprised of copper.

3. The structure according to claim 1, wherein thermally conductive epoxy attaches said cooling panel to the computer case.

4. The structure according to claim 1, wherein said cooling panel is attached to the computer case with bolts.

5. The structure according to claim 1, wherein said cooling panel is comprised of thermoelectric coolers located between a cold plate that radiates heat to the surroundings and a heatsink that contacts the computer case.

6. A method of cooling a computer, comprising the steps of:

providing a computer having a case;

selecting a thermoelectric cooling panel;

attaching the thermoelectric cooling panel with bolts to the computer case;

sealing the computer case to prevent air leakage;

monitoring ambient and dew point temperatures inside the computer case;

maintaining the temperature of the thermoelectric cooling panel above the dew point temperature; and

turning the computer off if the ambient temperature exceeds a set point value.