WO2000027176A1

WO2000027176A1 - Method for cooling electronic device and electronic device adopting the same

Info

Publication number: WO2000027176A1
Application number: PCT/KR1999/000470
Authority: WO
Inventors: Sang Cheol Lee
Original assignee: Zalman Tech Co., Ltd.
Priority date: 1998-11-04
Filing date: 1999-08-20
Publication date: 2000-05-11
Also published as: AU5308499A

Abstract

A method for cooling an electronic device such as a computer and an electronic device adopting the method. In the electronic device, inner elements (e.g. 20, 71) of the electronic device are almost completely sealed airtight, and the inner elements (e.g. 20, 71) can be cooled, preventing contamination of the inner elements (e.g. 20, 71) by dust adhering thereto and preventing noise generated within the case from being heard. In the method, an electronic device is completely closed airtight by a case and the heat generated in the closed space is radiated to the outside by forcibly circulating air within the electronic device. Also, the heat generated by heat generating elements can be cooled using a heat sink (21) installed to the same. In addition, the heated air in the case is transferred to an auxiliary cooling unit (81, 82) installed in the case and/or to the case and radiated to the outside of the electronic device.

Description

METHOD FOR COOLING ELECTRONIC DEVICE AND ELECTRONIC DEVICE ADOPTING THE SAME

Technical Field

The present invention relates to a method for cooling electronic devices such as components of a personal computer system, and an electronic device adopting the method, and more particularly, to a method for cooling electronic devices, in which an electronic device is sealed airtight by a case and heat generated by heat generating elements is radiated to the outside by an auxiliary cooling means installed in and/or on the case through air convection thereby.

Background Art In general, electronic devices, such as computers, televisions (TVs), videocassette recorders (VCRs), TV projectors, power supply units, projectors, slide projectors, overhead projectors (OHPs), facsimile machines, printers or photocopiers, includes a heat generating element. Thus, such apparatuses require a cooler. Here, the heat generating element may be a central processing unit (CPU), a hard disk drive (HDD), a power supply or a liquid crystal display (LCD) module. With use of the electronic devices, heat is produced by the heat generating element installed therein and a cooler such as a cooling fan is installed to cool the heat generating element. However, such cooler becomes a source of noise. As an example, referring to FIG. 1 , a computer comprises a power supply 2, a mother board 3 and an auxiliary memory device 4 within a case 1. Also, a CPU 5 is installed on the mother board 3, and cooling fans 6 are installed on the CPU 5, the power supply 2 and the case 1 , respectively. These elements are located within the space enclosed by the case 1 and blocked from the outside. The power supply 2 converts an alternating current (AC) of 110V or 220V into direct current (DC) and powers the mother board 3, the CPU 5, the auxiliary memory device 4 and the cooling fans 6. The cooling fans 6 are installed on the power supply 2 and the CPU 5 which generate a large amount of heat, to cool the same, and aids in the cooling of other elements.

The reason for cooling the power supply 2, the CPU 5 and other elements is that the heat generated from those elements themselves may shorten the life or cause malfunction of the elements. Moreover, if the power supply 2 overheats, there is a risk of fire. Also, overheating of the CPU 5 slows down the processing rate, and may shorten its life. In addition, if the degree of overheating is severe, the CPU 5 may cease to operate. Also, the auxiliary memory device 4 installed in the computer, which may be a hard disk drive (HDD), a CD-ROM drive or a DVD-ROM drive, generates noise (26~30dB) and heat during its operation, and performance thereof is lowered by the generated heat and dust, and thus malfunctions may occur.

As shown in FIG. 1 , the conventional computer adopts the cooling fans 6 as a cooler for cooling the CPU 5, the power supply 2 and other elements. The cooling fans 6 are installed on the power supply 2 and the CPU 5, and the case 1 to assist in the cooling. The cooling fans 6 provide air into the case 1 as power is applied to the power supply 2, and circulates the warm air out of the case 1 , thereby cooling the elements. However, noise generated by the cooling fans 6 when the cooling fans 6 rotate to circulate the air makes the working environment unpleasant. Also, dust may flow in together with the air as the cooling fans 6 rotate and may lower the efficiency in radiation of heat from the elements and reliability of the elements.

In the above-described conventional computer, noise of 30dB or more is generated and dust flowing in together with air may cause malfunction of the elements. The noise generated by the cooling fans or the auxiliary memory device can feel very loud in a space. However, when the cooling fans are out of order, the entire computer or some elements may not operate. Also, the noise generated by the auxiliary memory device cannot be removed.

Disclosure of the Invention

To solve the above problems, it is an object of the present invention to provide a method for cooling each heat generating element of an electronic device, capable of preventing dust from adhering to the inner space of the electronic device and blocking noise generated therein from escaping to the outside. Another object of the present invention is to provide an electronic device adopting the method capable of preventing dust from adhering to the inner space of the electronic device and preventing noise generated within the electronic device from being heard.

Yet another object of the present invention is to provide an electronic device adopting the method for cooling an auxiliary memory device installed in the electronic device, capable of preventing dust from adhering to the auxiliary memory device and preventing noise generated by the auxiliary memory device from being heard.

In one aspect of the present invention, there is provided a method for cooling an electronic device, wherein the electronic device comprising at least one heat generating element is sealed airtight by a case to block noise generated therein from escaping and infiltration of dust, and air in the case is forcibly circulated to transfer the heat generated when the heat emitting element is cooled by forced air cooling, to the case, radiating heat from the heat generating element to the outside.

Preferably, an auxiliary cooling means having a heat-absorbing portion which has an enlarged surface area and faces on the inside of the case, and a heat-emitting portion which has an enlarged surface area and faces the outside of the case, is installed so that the heat transferred to the heat- absorbing portion with forced air circulation is radiated to the outside through the heat-emitting portion.

Preferably, the heat-absorbing portion or heat-emitting portion of the auxiliary cooling means is a flower-type heat sink having a large surface area.

Preferably, the heat generated by the heat generating element is radiated by a thermocouple element which is installed between the heat- absorbing portion and heat-emitting portion of the auxiliary cooling means and forcibly transfers the heat from the heat-absorbing portion to the heat-emitting portion by applying electricity.

Preferably, a flower-type heat sink is used to radiate the heat of the heat generating element to the air in the case while being closed to the at least one heat generating element. In another aspect of the present invention, there is provided an electronic device comprising at least one heat generating element, comprising: a case which blocks noise generated within the electronic device from escaping and infiltration of dust and can radiate the heat generated therein; at least one air circulating fan installed in the case, which facilitates heat transfer to the outside through the case by forcibly circulating the air in the case to cool the heat generated by the heat generating element through air flow.

Preferably, the electronic device further comprises an auxiliary cooling means having a heat-absorbing portion which has an enlarged surface area and is installed in the case, and a heat-emitting portion which has an enlarged surface area and is installed out of the case, the auxiliary cooling means for radiating the heat transferred to the heat-absorbing portion through the forced air circulation by the air circulating fan, to the outside through the heat- emitting portion. Preferably, the electronic device further comprises a thermocouple element installed between the heat-absorbing portion and heat-emitting portion of the auxiliary cooling means, for forcibly transferring heat from the heat-absorbing portion to the heat-emitting portion by applying electricity.

Preferably, the electronic device further comprises a flower-type heat sink for radiating the heat of the heat generating element to the air in the case while being closed to the at least one heat generating element.

Preferably, the electronic device further comprises: first and second thermocouple elements installed in the case; first and second tanks attached to heat-emitting surfaces of the first and second thermocouple elements, respectively; heat sinks attached to heat-absorbing surfaces of the first and second thermocouple elements; a radiator installed outside of the case, connecting the first and second tanks, through which fluid contained in one of the tanks, attached to either the first or second thermocouple element to which electricity is applied, flows while being vaporized, so that the heat transferred to the fluid is cooled; and a controller for controlling whether to apply electricity to the first or second thermocouple element or to break the electricity.

Preferably, fins are formed inside and outside of the case. In still another embodiment of the present invention, there is provided an electronic device including a case, a circuit board installed in a main frame of the case, at least one heat generating element installed on the circuit board and an auxiliary memory device installed in the main frame, the electronic device comprising: a cover which surrounds the auxiliary memory device to prevent noise generated by the auxiliary memory device from escaping and to prevent dust from adhering to the auxiliary memory device, and fixes the auxiliary memory device to the main frame; and an air circulating fan installed in the cover, for circulating the air in the cover.

Preferably, the electronic device further comprises at least one auxiliary cooling means having a heat-absorbing portion which has an enlarged surface area and is installed in the cover, and a heat-emitting portion which has an enlarge surface area and installed out of the cover. Preferably, the electronic device further comprises: an auxiliary cooling means attached to the at least one heat generating element; and at least one air circulating fan installed in the main frame, for sending air while rotating at a speed at which noise is not generated.

Preferably, the auxiliary cooling means is a flower-type heat sink. Therefore, in the cooling method for an electronic device and the electronic device adopting the same according to the present invention, the inner elements can be protected dust adhering thereto and can be cooled without generation of noise.

Brief Description of the Drawings

FIG. 1 is a perspective view of a conventional computer;

FIG. 2 is a conceptual view of a computer case, a central processing unit (CPU) and a fan, illustrating a method for cooling an electronic device according to the present invention;

FIGs. 3A and 3B are graphs illustrating the change in the internal temperature of a computer and the temperature of the CPU with time when the temperature of external air is fixed, when the computer is cooled by the conventional method and the method according to the present invention, respectively;

FIG. 4 is an exploded perspective view of a computer adopting the cooling method according to the present invention; FIG. 5 is an assembled perspective view of the computer of FIG. 4;

FIG. 6 is a perspective view showing heat-dissipating fins formed in a case of a computer adopting the cooling method according to the present invention;

FIG. 7 is a perspective view of a heat sink which can be attached to a heat-absorbing surface and a heat-emitting surface of the thermocouple element shown in FIG. 4;

FIG. 8 is a perspective view of a pipe radiator attached to the thermocouple element of FIG. 4, for absorbing heat from the thermocouple element or dissipating the heat of the thermocouple element to the surrounding air; and

FIG. 9 is an exploded perspective view of a noiseless hard disk drive (HDD) case adopted by the present invention.

Best mode for carrying out the Invention Referring to FIG. 2, the temperature of a central processing unit (CPU)

20 installed in a case 10 varies depending on the air volume and air flow pressure of air moved by a fan 30 and the temperature of air 40 within the case 10. That is, when a fan having a length of 29mm rotates at 2,400rpm to achieve an air flow volume of 1.18 rrWmin and the air flow pressure of 3.0 mmH₂O while the inner temperature of the case 10 is maintained at 30° C, the temperature of the CPU 20 is maintained at 40°C. Thus, in order to keep the temperature of the CPU 20 at 40° C when the inner temperature of the case 10 is 35°C, the fan 30 is rotated at 3,600rpm such that the air flow volume and the air flow pressure are 1.58 m³/min and 7.0 mmH₂O, respectively. In other word, the CPU 20 can be maintained at a desired temperature by controlling the rate of rotation of the fan 30 in consideration of the change in temperature within the case 10.

Preferably, a heat sink for the CPU 20 is a flower-type heat sink 83 as shown in FIG. 7. The flower-type heat sink is made of a metal such as copper (Cu) or aluminum (Al), and a plurality of unit heat sink plates each having fixing holes overlap in the lower part of the heat sink and are separated at an angle in the upper part thereof, like a flower in full bloom, such that a heat transfer path becomes short and the heat emission area becomes large. Also, due to low heat resistance, the heat generated by the CPU can be effectively further radiated.

On the other hand, when the inner temperature of the case 10 is higher than the external temperature, heat radiates from inside the case 10 to the outside. Here, a large amount of heat is radiated through the case when the case 10 is formed of a heat conductive material, the contact surface areas between the case 10 and the air 40 therein and between the case 10 and air 50 outside of the case 10 are large, and the difference in temperatures between air inside and outside of the case 10 increases. For example, assuming that the amount of heat generated in the case 10 is 40W and the temperature of the air 50 outside of the case 10 is 25°C, when the case 10 is formed of aluminum (Al), heat is continuously transferred through the case 10 to the outside, thereby keeping the temperature of the air inside the case 10 at 35°C.

As described above, in the method for cooling an electronic device and the electronic device adopting the same according to the present invention, heat generating elements, for example, the CPU 20, are completely enclosed by the case 10 made of a heat conductive material such that heat is actively radiated through the case 10 as the temperature of the air 40 inside the airtight case 10 increases. In addition, the air 40 within the case 10 is circulated by the fan 30, such that the temperature of the CPU 20 is kept at an appropriate level.

Referring to FIGs. 1 , 2, 3A and 3B, when the external air (A) of the computer is maintained at 25°C, the temperature of the air (B) 40' in the computer increases and reaches equilibrium within a predetermined time as the conventional computer of FIG. 1 which is not completely air tight operates. Here, the temperature of the CPU 5 increases as indicated by line D to reach equilibrium within a predetermined time. Meanwhile, the temperature of the air 40 within the airtight computer (see FIG. 2) according to the present invention increases (B') to reach equilibrium within a predetermined time. When the air flow volume and the air flow pressure within the case increase by increasing the rotation rate of the fan 30, the temperature of the CPU 20 is kept at the same temperature (D') as that of the conventional CPU. The temperature of the CPU 20 increases (E) if the airflow volume and the airflow pressure within the case are equal to those as in the conventional computer. As the elements of the computer are completely sealed by the case to be protected from noise and dust, the noise generated inside does not come out of the case and inflow of dust from the outside is prevented. At the same time, the heat generated in the case can be radiated actively to the outside, and the temperature of the inner heat generating elements can be kept at a desired temperature by controlling the size and the number of turns of the cooling fans. The technology for controlling cooling efficiently by sensing the temperatures of the heat generating elements and then adjusting the number of turns of the cooling fans, as another embodiment of the present invention, is obvious to those skilled in the art, thus an explanation thereof is not provided. An explanation of designing the cooling fans in consideration of cooling capacity according to the heat value of each heat generating element is also omitted.

In the structure and operation of an electronic device adopting the cooling method according to a preferred embodiment of the present invention, referring to FIGs. 4 and 5, a mother board 60, a CPU 20, a power supply 71 , an auxiliary memory device 70, a fan 30 are installed in a computer, and these elements are sealed airtight by a case 10. Also, a door 11 is attached to the case 10 such that a recording medium can be inserted into and withdrawn from the auxiliary memory device 70. A hole 90 through which a bundle of wires (not shown) come outside is formed in the bottom of the case 10, and a plug 91 is plugged in the hole 90, to prevent noise within the case from escaping and infiltration of dust therein.

Preferably, the case 10 is formed of a heat conductive metal such as aluminum (Al), copper (Cu) or iron (Fe). However, the case 10 may be formed of a non-metallic material such as glass, plastic or acryl resin, which has a comparatively low heat conductivity, in consideration of the quantity of heat generated within the computer. In consideration of the sound insulation effect and cost, it is preferable that the case 10 and the door 11 are formed of glass, plastic or acryl resin having excellent sound insulation effect. Also, in order to further radiate the heat to the outside, a general heat sink or the flower-type heat sink 83 shown in FIG. 7 may be adopted as an auxiliary cooling means, and alternatively, a thermocouple element capable of forcibly radiating heat to the outside is further installed in the case 10 in consideration of the heat value in the case.

As shown in FIG. 7, a plurality of unit heat sink plates each having a plurality of fixing holes are overlapped at the lower part of the heat sink, forming a heat-absorbing surface, and the other sides of the unit heat sinks are bent at an angle along protrusions formed in each unit heat sink, which form a heat-emitting surface, to be separated from each other, resulting in the flower-type heat sink 83 shown in FIG. 7. Here, the heat-emitting surface is larger than the heat-absorbing surface, thereby improving the cooling effect. The shape of the flower-type heat sink is not limited to the shape shown in FIG. 7 and can be varied according to the shapes of heat generating elements to be cooled.

Because the heat transfer capacity of the thermocouple element 80 improves as the temperature of its heat-absorbing surface becomes higher than that of its heat-emitting surface, preferably, heat sinks 81 and 82 as an auxiliary cooling means are attached to the heat-absorbing surface and the heat-emitting surface of the thermocouple element 80, thereby actively radiating the heat to the outside. More preferably, the heat sinks to be attached are the flower-type heat sink 83 shown in FIG. 7. Even more preferably, two thermocouple elements, i.e., first and second thermocouple elements 80a and 80b, are used together with a pipe radiator 100 as shown in FIG. 8. Also, the heat sink may be used instead of a general heat sink 21 for the CPU 20 shown in FIG. 4.

The pipe radiator 100 comprises a first tank 101 for absorbing heat generated in contact with the heat-emitting surface of the first thermocouple element 80a attached to the case, a second tank 102 for absorbing heat generated in contact with the heat-emitting surface 80b attached to the case, a fluid path 103, and fluid contained in one tank, which is evaporated by absorbing heat in the tank, cooled passing the fluid path and condensed into a liquid. The returned liquid is contained in the other tank. Here, the pressures of the first and second tanks 101 and 102 and the fluid path 103 are controlled such that the fluid is vaporized and then condensed at a desired temperature. When electricity is applied to the first thermocouple element 80a and current flow through the second thermocouple element 80b is blocked by a controller (not shown), the first thermocouple element 80a absorbs heat from the heat generating elements or from the inner space of the case, and the heat is transferred to the fluid contained in the first tank 101. As a result, the fluid contained in the first tank 101 is vaporized and then moved into the second tank 102 through the fluid path 103 by the inner pressure of the first tank 101. Meanwhile, when electricity is applied to the second thermocouple element 80b and the electricity flow through the first thermocouple element 80a is blocked by the controller, the second thermocouple element 80b absorbs heat from the heat generating elements or from the inner space of the case, and the heat is transferred to the fluid contained in the second tank 101. As above, the heat transferred to the fluid is cooled while the fluid flows through the narrow and thin fluid path 103, thereby emitting the heat generated in the case to the outside.

As shown in FIG. 6, when the case 10 is processed to have sides formed of heat-dissipating fins 12 in order to increase the heat-emitting area, the contact surface area between the case 10 and the inner or outer air increases, so that the amount of heat emitted increases. In other words, when the computer is completely airtight by the case, the temperature within the case 10 is increased to a higher level than the external temperature of the case 10. In this state, if the air-to-case contact surface area is large, the heat generated in the case can effectively be transferred to the outside.

Alternatively, a noiseless computer can be attained by making airtight a hard disk drive (HDD) which is a heat and noise generating element, instead of making the entire computer airtight, using a sound insulation member and a case, according to the cooling method of the present invention. Here, the cooling fans for a power supply unit and a CPU which are noise sources installed in the computer, are operated at a rotation rate at which noises is nearly not generated, so that the problem of noise can be solved.

Referring to FIG. 9, an HDD 200 is almost completely enclosed by a sound insulation member 201 and a cover 202, and a fan 203 is installed in the cover 202. Also, a heat sink 204 is installed in the cover 202. As a result, noise generated by the HDD 200 is blocked by the sound insulation member 201 and the cover 202, and the heat generated by the HDD 200 is moved to an inner heat sink 204a with a stream of air generated by the fan 203 and then emitted to the outside through an external heat sink 204b. In the case of limiting the rotation rate of the cooling fans for cooling the power supply unit and CPU so as not to generate noise, preferably, the size of those cooling fans is increased to generate a large amount of air and a heat sink having a large heat-emitting area is adopted. Also, a heat sink for a CPU may be the flower-type heat sink shown in FIG. 7.

When the inner temperature of the cover 202 exceeds a desired temperature because a fan 203 installed in the cover 202 does not work or due to other reasons, the HDD 200 may be damaged. Thus, an electronic circuit for operating a buzzer 206 or an alarm lamp (not shown) by sensing the inner temperature of the cover 202 and the rotation of the fan 203 may be installed to indicate an excess increase in the inner temperature of the cover 202. Preferably, the electronic circuit comprises a temperature switch 205 installed in the cover 202 and the buzzer 206 which can be installed inside or outside of the cover 202, wherein the temperature switch 205 operates when the inner temperature of the cover 202 reaches a predetermined temperature, sounding the buzzer 206.

Industrial Applicability

As described above, in the method for cooling an electronic device and the electronic device adopting the method according to the present invention, the electronic device are completely sealed airtight to block noise generated by the inner elements from escaping, and the air flow in the apparatus is controlled to be strong, such that the heat generated within the case is actively emitted to the outside. As a result, the temperatures of the inner elements are maintained at an appropriate level, preventing noise generated within the case from being heard. Also, dust adhering to the inner elements is prevented. While the present invention has been illustrated and described with reference to specific embodiments, further modifications and alterations within the spirit and scope of this invention as defined by the appended claims will occur to those skilled in the art.

Claims

What is claimed is:

1. A method for cooling an electronic device, wherein the electronic device comprising at least one heat generating element is sealed airtight by a case to block noise generated therein from escaping and infiltration of dust, and air in the case is forcibly circulated to transfer heat generated from the heat generating element to the case by forced air cooling, and to thus radiate heat from the heat generating element to the outside.

2. The method of claim 1 , wherein an auxiliary cooling means having a heat-absorbing portion which has an enlarged surface area and faces the inside of the case, and a heat-emitting portion which has an enlarged surface area and faces the outside of the case, is installed at the case so that the heat transferred to the heat-absorbing portion with forced air circulation is radiated to the outside through the heat-emitting portion.

3. The method of claim 2, wherein the heat-absorbing portion or heat-emitting portion of the auxiliary cooling means is a flower-type heat sink having a large surface area.

4. The method as in one of claims 1 -3, wherein the heat generated by the heat generating element is radiated by a thermocouple element which is installed between the heat-absorbing portion and heat-emitting portion of the auxiliary cooling means and forcibly transfers the heat from the heat- absorbing portion to the heat-emitting portion by applying electricity.

5. The method of any one of claims 1 -4, wherein a flower-type heat sink is used to radiate the heat of the heat generating element to the air in the case while being closed to the at least one heat generating element.

6. An electronic device comprising at least one heat generating element, comprising: a case which blocks noise generated within the electronic device from escaping and infiltration of dust and can radiate the heat generated therein; at least one air circulating fan installed in the case, which facilitates heat transfer to the outside through the case by forcibly circulating the air in the case to cool the heat generated by the heat generating element through air flow.

7. The electronic device of claim 6, further comprising an auxiliary cooling means installed at the case, having a heat-absorbing portion which has an enlarged surface area and faces the inside of the case, and a heat- emitting portion which has an enlarged surface area and faces the outside of the case, the auxiliary cooling means for radiating the heat transferred to the heat-absorbing portion through the forced air circulation by the air circulating fan, to the outside through the heat-emitting portion.

8. The electronic device of claim 7, further comprising a thermocouple element installed between the heat-absorbing portion and heat- emitting portion of the auxiliary cooling means, for forcibly transferring heat from the heat-absorbing portion to the heat-emitting portion by applying electricity.

9. The electronic device as in one of claims 6-8, further comprising a flower-type heat sink for radiating the heat of the heat generating element to the air in the case while being closed to the at least one heat generating element.

10. The electronic device of claim 6, further comprising: first and second thermocouple elements installed in the case; first and second tanks attached to heat-emitting surfaces of the first and second thermocouple elements, respectively; heat sinks attached to heat-absorbing surfaces of the first and second thermocouple elements; a radiator installed outside of the case, connecting the first and second tanks, through which fluid contained in one of the tanks, attached to either the first or second thermocouple element to which electricity is applied, flows while being vaporized, so that the heat transferred to the fluid is cooled; and a controller for controlling whether to apply electricity to the first or second thermocouple element or to break the electricity.

11. The electronic device as in one of claims 6-10, wherein fins for radiating heat are formed inside and outside of the case.

12. An electronic device including a case, a circuit board installed in a main frame of the case, at least one heat generating element installed on the circuit board and an auxiliary memory device installed in the main frame, the electronic device comprising: a cover which surrounds the auxiliary memory device to prevent noise generated by the auxiliary memory device from escaping and to prevent dust from adhering to the auxiliary memory device, and fixes the auxiliary memory device to the main frame; and an air circulating fan installed in the cover, for circulating the air in the cover.

13. The electronic device of claim 12, further comprising at least one auxiliary cooling means having a heat-absorbing portion which has an enlarged surface area and is installed in the cover, and a heat-emitting portion which has an enlarge surface area and installed out of the cover.

14. The electronic device of claim 13, further comprising: an auxiliary cooling means attached to the at least one heat generating element; and at least one air circulating fan installed in the main frame, for sending air while rotating at a speed at which noise is not generated.

15. The electronic device of claim 13 or 14, wherein the auxiliary cooling means is a flower-type heat sink.

16. The electronic device as in one of claims 12-14, further comprising: a temperature switch installed in the cover; and a buzzer or an alarm lamp installed in or out of the cover.