JP2000188493A - Cooler with electromagnetic shield function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase noise suppressing function as much as possible while keeping the cooling function. SOLUTION: A cooler comprises a heat dissipating element 3 arranged to receive heat conducted from an electric apparatus element 1 and to dissipate the received heat into the outer space, and a tubular conductor duct 2 made of a conductive material to have an opening (21) 22 communicating with the outer space at at least one end with the tube wall part being arranged to cover the electric apparatus element 1. The heat dissipating element 3 is contained in the inner space 27 of the conductor duct 2 and arranged to dissipate the received heat through the opening (21) 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a CPU (Central
The present invention relates to a cooling device having an electromagnetic shielding function used to simultaneously suppress generation of noise from electronic device elements such as a processing unit (central processing unit) and cool the electronic device elements.

[0002]

2. Description of the Related Art Conventionally, in an electronic device element such as a CPU, the element generates heat in accordance with the operation thereof. Cooling is taking place. On the other hand, the operation frequency of the CPU tends to be higher due to a demand for high-speed processing, and a harmonic component (noise) is generated along with this. May be exerted.

For this reason, a cooling device that performs electromagnetic shielding in addition to cooling has been proposed (for example, Japanese Patent Application Laid-Open No. 8-125).
No. 363). In this device, a cooling unit having an electric fan is mounted on an integrated circuit, and a shield is mounted on a circuit board so as to cover the entire unit via an elastic body while the cooling unit is mounted. It is.

However, in the cooling device proposed above, it is necessary to provide a suction port and an exhaust port for forced air cooling by an electric fan in the shield, and the shield only electromagnetically shields the shield. Therefore, there is an inconvenience that generation of noise is not sufficiently suppressed.

Here, it is considered that if the entire CPU including the electric fan is completely shielded with a highly magnetically permeable metal, even if radiated noise is generated, it can be prevented from leaking to the outside. However, when the shield is completely shielded, heat dissipation is hindered, and the cooling function is hindered.

[0006] In addition, the operating frequency in recent years has been remarkably increased (for example, 350 to 450 MHz). As a result, the heat generated from the CPU is further increased and higher harmonic components (for example, the operating frequency) are increased. (1 GHz or more, which is 3 times or more of the above) tends to be radiated as noise, and a higher suppression technology and a higher cooling technology for noise generation are required.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has an electromagnetic shielding function capable of enhancing a noise generation suppressing function as much as possible while maintaining a cooling function. It is an object to provide a cooling device having the same.

[0008]

According to the present invention, there is provided a cooling apparatus having an electromagnetic shielding function, which is provided so as to receive heat conduction from an electronic device element to the electronic device element, and transfers the received heat to an external space. A heat dissipating element that dissipates heat, and is formed in a tubular shape by using a conductive material so as to have an opening communicating with the external space at least at one end, and a tube wall portion is disposed on the electronic device element so as to cover the electronic device element. Wherein the heat dissipation element is housed in an internal space of the conductor duct, and is arranged such that the conduction heat is radiated through the opening.

In the present invention, the heat radiation element is formed integrally with the conductor duct so as to project from the inner peripheral surface of the pipe wall of the conductor duct toward the internal space of the conductor duct,
Further, it is preferable that the outer peripheral surface of the tube wall of the conductor duct is disposed so as to cover the electronic device element with the electronic device element and to be in contact with receiving the heat conduction, and the conductor duct is open at both ends. It is preferable that the opening has one end and the one end opening is arranged apart from the electronic device element, while the other end opening is provided so as to surround the periphery of the electronic device element including the heat radiation element, and Preferably, the opening of the conductor duct is dimensioned to block the emission of harmonic components radiated from the electronic device element from the opening, and furthermore, the outer surface of the conductor duct is made of a high dielectric loss material or It is preferably covered by a film formed of any of the soft magnetic materials, and also creates an air flow circulating between the inner space and the outer space of the conductor duct through the opening It is preferably provided with a dynamic fan, further thereon the surface layer constituting at least the outer surface of the electric fan is formed by one of a high dielectric loss material or a soft magnetic material is preferable.

Here, the heat radiating element is constituted by, for example, one or more heat radiating fins.

[0011]

In the present invention, since the electronic device element and the heat radiation element are both housed and covered in the inner space of the conductor duct, the noise radiated from the electronic device element and the tip of the heat radiation element become an antenna. Noise radiated through the conductor duct is confined inside the conductor duct. And the noise propagates through the conductor duct,
Alternatively, loss and attenuation occur while the light is repeatedly reflected in the inside of the conductor duct and reaches the opening, so that a frequency component equal to or lower than the cut frequency determined by the size of the opening leaks into the external space. Therefore, by setting the size of the opening so that the cut frequency is higher than the noise generated from the electronic device element,
The noise of the harmonic component unique to the electronic device element is reliably suppressed from being released from the opening of the conductor duct to the external space, that is, the internal space of the housing of a so-called personal computer or the like to which the electronic device element is mounted. Will be. This makes it possible to reliably prevent a malfunction from occurring due to the noise riding on a signal such as a signal line wired in the internal space of the housing.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments, but the present invention is not limited to only such embodiments.

Embodiment 1 A cooling device according to Embodiment 1 of the present invention is shown in FIG. 1, in which reference numeral 1 denotes an electronic device element (specifically, a CPU), reference numeral 2 denotes a conductor duct, reference numeral 3 denotes a heat radiation element, Reference numeral 4 indicates an electric fan. In the first embodiment, the heat radiation element 3 and the conductor duct 2 are integrally formed, and the duct wall of the conductor duct 2 covers the CPU 1 and conducts heat to the heat radiation element 3.

Hereinafter, the positional relationship between the CPU 1 and the conductor duct 2 will be described with reference to FIG.
Therefore, if the actual mounting direction of the CPU 1 with respect to the housing of the personal computer changes, the installation direction of the conductor duct and the like also changes accordingly. This is the same in the following embodiments.

The conductor duct 2 has openings 21 and 22 at both ends in the axial direction of the duct. The conductor duct 2 is made of the above-described conductive material so that the size of one side is a rectangular tube having a rectangular cross section substantially the same as the width Y of the CPU 1. It was formed. The conductor duct 2 is arranged so that its duct axis extends in the length X direction of the CPU 1, and is attached to the upper surface of the CPU 1 so that the duct wall 23 is in close contact with the upper surface of the CPU 1. Thus, the duct wall 23 covers the entire upper surface of the CPU 1. The attachment may be performed by means of bonding, screwing, crimping, fitting, etc.,
In the example shown in the figure, the protrusions (see FIG. 2) formed on the upper surface of the CPU 1 are pressed into the fitting holes formed in the duct wall portion 23 so as to be pressed.

Here, the conductor duct 2 is formed of a conductive material and functions as a kind of waveguide, and functions as a high-pass filter that blocks (cuts) electromagnetic waves (noise) of a certain frequency or less. . In this case, regardless of whether a rectangular shape is adopted as the cross-sectional shape of the conductor duct 2 as shown in the drawing, or any shape such as a circular shape, an elliptical shape, or a tapered shape, the opening of the conductor duct 2 is formed. It is preferable to set the size according to the frequency of the noise to be suppressed so as to cut off noise below a specific frequency from the conductor duct 2 to the outside.

The dimensions may be set by a well-known method for a waveguide. Specifically, the cut frequency is f (Hz), the light speed is ν (3 × 108 m), and the length in the case of a rectangular duct is long. If the side is a (m) and the diameter of the circular duct is a (m), formula (1) is used when the conductor duct 2 has a rectangular cross section, and (2) when the conductor duct has a circular cross section. The dimension or the diameter a of the long side a may be determined so as to satisfy the respective expressions. At this time, the dimensions may be determined with respect to the propagation mode having the highest cut frequency among the modes of the propagating electromagnetic wave.

F = ν / (2 · a) (1) f = ν / (2.613 · a) (2)

For example, as the electronic device element 1, a Pentium II (trade name) CP having an operating frequency of 350 MHz is used.
When U1 is selected, it is a triple harmonic component.
A high radiation intensity level of 05 GHz has been verified theoretically and experimentally. When the operating frequency is set as the cutoff frequency f, the opening size of the rectangular conductor duct 2 is determined by the equation (1) from the CPU of the Pentium II.
Dimension (143mm ×
65 mm).

Further, with respect to the plate thickness and duct length of the conductor duct 2, the conductor duct 2 of the present invention is unlikely to be an original waveguide, and makes it difficult for electromagnetic waves to propagate as much as possible, thereby attenuating noise in the conductor duct 2. Therefore, it is preferable to make the plate thickness as thin as possible (for example, 1.0 mm) and also make the duct length as long as possible.

As a conductive material for forming the conductor duct 2, a metal such as Cu is generally used, but any material other than a metal may be used as long as the material can transmit electromagnetic waves. More preferably, the conductor duct is formed using a material that has conductivity but has high propagation resistance and causes greater attenuation. Preferred conductive materials used in the present invention, for example, beryllium,
Aluminum, brass, iron, etc., having a large internal surface roughness may be used. Also, its thickness is
It is preferable that the distance be 2 mm or less.

Except for the lower duct wall 23 of the conductor duct 2, a predetermined radio wave absorbing material is provided on each of the three outer surfaces of the upper duct wall 24 and the left and right duct walls 25 and 26. A radio wave absorbing sheet 5 (shown only in FIG. 2) formed of (non-conductive material) is adhered by means such as bonding, and the entire surface of the conductor duct 2 that contacts the external space is covered by the radio wave absorbing sheet 5. It is covered. Accordingly, noise that may be radiated from each outer surface of the conductor duct 2 is also absorbed, and the noise leakage to the external space is reliably suppressed. Note that, instead of the radio wave absorbing sheet 5, a film made of a high dielectric loss material or a soft magnetic material may be used.

The duct wall 23 of the conductor duct 2
As shown in FIG. 2, the lower radiating fins 31 are located on the inner surface of each
Project upward, and these lower radiation fins 31, 31,
... extend parallel to each other over the entire length in the direction of the length X. Further, the duct wall 24 on the upper side of the conductor duct 2
Are formed on the inner surface of each of the lower heat radiation fins 31 so as to protrude toward the inner space of the conductor duct 2, and each of the upper heat radiation fins 31, 31 The lower radiating fins 31 are vertically opposed to each other. In addition, by connecting the protruding ends of the heat radiation fins 31 on the upper and lower sides, both openings 21,
The amount of protrusion of each of the heat radiation fins 31 on the upper and lower sides is set so that a circular space 27 penetrating through the heat sink 22 is formed. Has become.

As is apparent from the above description, in the first embodiment, the plurality of radiation fins 31 and 3 on the upper and lower sides are used.
The heat dissipating element 3 is constituted by 1,. In addition, when using a radiation fin, it may be one, but it is preferable to install two or more radiation fins apart from each other, and when installing two or more radiation fins, increase the number as much as possible and It is preferable to make the gap between two adjacent radiation fins as large as possible. Further, in order to receive the heat conduction from the electronic device element, it is preferable that the heat radiating element is attached to the electronic device element as closely as possible over a large area, and is directly attached thereto. An adhesive layer made of a good conductor may be provided.

An electric fan 4 having a size smaller than the inner dimension and covering the circular space 27 is attached to the opening 21 at one end side of the conductor duct 2 in the duct axis direction. An air flow through the circular space 27 is forcedly generated from one of the openings 21 and 22 to the other. Case 4 of this electric fan 4
1. Each outer surface layer of the fan blades 42 and a motor case (not shown) is formed of the same radio wave absorbing material as described above. The formation of each outer surface layer may be performed by means such as attaching or coating a flexible thin film sheet made of the above material. Note that a flexible thin film sheet of a high dielectric loss material or a soft magnetic material may be attached instead of the radio wave absorbing material.

In the first embodiment, however, C
Heat generated from the PU 1 is transmitted to the lower radiation fins 31 through the duct wall 23 of the conductor duct 2 and to the duct walls 25 and 2.
6 and 24, heat is conducted to the upper radiation fins 31, respectively, and the electric heat is radiated from the upper and lower radiation fins 31 to mainly the circular space 27 in the conductor duct 2, and the circular space 27 and the opening 21 or 22 are formed. Through to the outside space. At this time, the heat radiation is forcibly discharged by the operation of the electric fan 4.

On the other hand, noise radiated from the CPU 1 into the internal space of the conductor duct 2 is cut at both openings 21 and 22, while radiation from the outer surface of the conductor duct 2 is also suppressed by absorption loss by the radio wave absorbing film 5. Will be done. Moreover, since each of the heat radiation fins 31 is accommodated in the internal space of the conductor duct 2, noise radiated from the projecting tip of each of the heat radiation fins 31 as an antenna is confined in the conductor duct 2 and attenuated.

Embodiment 2 FIGS. 3 and 4 show Embodiment 2 of the present invention. In Embodiment 2, a conductor duct 6 having a rectangular cross section and a heat radiation element 7 are formed separately from each other. The duct shaft is arranged so as to extend in a direction perpendicular to the upper surface of the CPU 1 (vertical direction in FIGS. 3 and 4).

The conductor duct 6 has openings 61 and 62 at both ends in the axial direction of the duct.
66 is formed of the above-described conductive material so as to have a size that can cover the outer periphery of the CPU 1. The dimension a of the long side constituting the upper end side opening 62 is determined by the above-mentioned equation (1). That is, for the dimension a, a frequency value higher than the frequency value of the harmonic component is substituted into the formula (1) as a cut frequency f in order to cut a harmonic component three to five times the operating frequency of the CPU 1. It is what I sought. As a result, the higher harmonic component on the lower frequency side than the cut frequency f is cut, and the noise of the higher harmonic component is suppressed from being released from the opening 62 to the external space. The height of the conductor duct 6 is set to be as high as possible according to the internal space of the housing of the personal computer in which the CPU 1 in which the conductor duct 6 is mounted is arranged to attenuate noise. Preferred above. Specifically, when the conductor duct 6 is formed of a 2 mm thick copper plate to have a height of 30 cm, attenuation of 6 dB is obtained at the voltage level.

Further, all of the outer peripheral surfaces of the four duct walls 63 to 66 are the same as in the first embodiment.
Only shown).

The heat dissipating element 7 comprises a substrate 71 and the substrate 7
1 a plurality of radiating fin groups 72 to 74 projecting upward from above
It is composed of Each radiating fin group 72, 73, 7
4 is provided with a plurality of radiating fins 75, 75,. Then, the radiation fin groups 72, 7 adjacent to each other are provided.
A gap is formed at a predetermined interval between 3, 73 and 74, and the board 71 and the CPU 1 are attached using this gap.

The electric fan 4 is mounted on the upper end of the radiating fin group 73 at the central position. The operation of the electric fan 4 causes the space between the radiating fins 75 and the opening 62 on the upper end side of the conductor duct 6 to move. The air circulating between the fins 75 is forcibly generated, so that the heat radiated between the radiating fins 75 is forcibly diffused into the external space through the upper end side opening 62.

Then, each duct wall 6 on the lower opening side
The conductor duct 6 is fixed so as to cover the CPU 1 from above so that the entire periphery of the CPU 1 is shielded by 3-66, whereby both the heat radiation element 7 and the electric fan 4 It is housed in the internal space 67 of the duct 6 and is shielded.

In the second embodiment, the heat generated by the CPU 1 is conducted to the respective radiating fins 75 via the substrate 71,
Heat is radiated from each of the radiating fins 75 to a lower portion of the internal space 67. Then, the air heated by the heat radiation rises toward the upper opening 62 and is discharged to the external space through the opening 62. Thus, the heat radiated from each of the radiating fins 75 is effectively discharged to the external space. At this time, if the electric fan 4 is operated, the radiated heat can be efficiently and rapidly discharged to the external space. Therefore, the electric fan 4
Are not indispensable components, and the internal space 67 and the external space (the internal space of the housing) without the electric fan 4.
By effectively diffusing heat due to the temperature difference between the CPU 1 and the CPU 1, the CPU 1 can be effectively cooled so as not to be heated to a predetermined temperature or higher.

On the other hand, since the entire outer periphery of the CPU 1 is covered by the conductor duct 6, and furthermore, all of the heat radiation element 7 and the electric fan 4 are covered by the conductor duct.
Both the noise radiated from 1 and the noise radiated from the projecting tip of each radiating fin 75 as an antenna are radiated in a state of being confined in the internal space 67 of the conductor duct 1. Then, the noise radiated into the internal space 67 is cut at the opening 62 that is only open to the external space. That is, the opening 62 for heat diffusion also plays a role of cutting noise radiated from the CPU 1 at the same time. Therefore, it is possible to maintain the cooling function for the CPU 1 and at the same time suppress the leakage of noise to the outside as much as possible. In addition, the radiation of the noise from the outer surface of the conductor duct 6 can be suppressed by the radio wave absorbing film 5.

Third Embodiment FIG. 5 shows a third embodiment of the present invention. The third embodiment is based on the structure of the second embodiment, and has a conductor duct having a circular cross section instead of the conductor duct 6 having a rectangular cross section in the second embodiment. 8
Is used.

That is, in the third embodiment, the heat radiating element 9 is mounted on the upper surface of the CPU 1 such that the substrate 91 is in close contact therewith and covers substantially the entire surface of the CPU 1. The lower end opening 81 of the conductor duct 8 is covered and fixed from above so as to surround it. As a result, both the CPU 1 and the heat radiation element 9 are accommodated in the internal space 83 of the conductor duct 8. Also, the diameter a of the upper end opening 82 of the conductor duct 8
Is set based on the above equation (2).

The heat dissipating element 9 is composed of a substrate 91 and a plurality of heat dissipating fins 92, 92,.
It is comprised by these. The heat radiation element 9
An electric fan 4 similar to that of the second embodiment may be provided at the upper end.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to only such embodiments, and various modifications are possible. For example, as shown in FIGS. 6 to 8, radiation fins 7 of conductive ducts 6 and 8 are provided.
An opening O, for example, a slit, a mesh, a small hole, or the like may be provided at a position corresponding to the base end portion of each of the fifth and 92 to improve the cooling efficiency. Further, as the heat radiation element, a heat sink having a heat storage material therein may be used instead of the heat radiation fin. Alternatively, a radiation fin and a Peltier element are used. Further, the electronic device element is not limited to the CPU, and may be various electronic device elements that generate high-frequency noise.

[0040]

As described above, according to the cooling device having a shielding function of the present invention, heat generated from electronic equipment elements such as a CPU is effectively radiated and diffused so that the temperature does not rise above a predetermined temperature. And the noise, which is a harmonic component generated from the electronic device element, is emitted to an external space, that is, an internal space of a housing of an electronic device such as a personal computer to which the electronic device element is mounted. An excellent effect is obtained that the electromagnetic shielding function of more reliably suppressing the noise can be satisfied at the same time.

Further, in order to eliminate the inconvenience that the presence of an opening required for heat dissipation and diffusion hinders the suppression of noise emission, attention is paid to the fact that the opening is used to cut off noise emission. A means for forming a duct for leading out the radiated air from a conductive material and using the conductor duct as a kind of filter for cutting the noise contrary to the original use of the waveguide is adopted. Therefore, an excellent effect that both the cooling function and the electromagnetic shielding function can be easily and reliably realized can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a cooling device having an electromagnetic shielding function according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a partially cutaway perspective view of a cooling device having an electromagnetic shielding function according to a second embodiment of the present invention.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a perspective view of a cooling device having an electromagnetic shielding function according to Embodiment 3 of the present invention.

FIG. 6 is a view corresponding to FIG. 3, showing an opening provided at a position corresponding to the base end of the heat radiation fin of the conductive duct.

FIG. 7 is a diagram corresponding to FIG. 4;

FIG. 8 is a diagram corresponding to FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU (electronic equipment element) 2,6,8 Conductor duct 3,7,9 Heat dissipation element 4 Electric fan 5 Electric wave absorption film (film) 21,22 Opening 61,81 Opening (other end opening) 62,82 Opening (opening at one end) 27, 67, 83 Internal space

Claims (8)

[Claims] 1. A heat dissipating element arranged to receive heat conduction from an electronic device element to the electronic device element, and dissipating the received conductive heat to an external space, and an opening communicating at least one end with the external space. A conductive duct formed of a conductive material so as to have a tube wall portion disposed so as to cover the electronic device element with respect to the electronic device element. A cooling device having an electromagnetic shielding function, wherein the cooling device is housed in an internal space and arranged so that the conduction heat is radiated through the opening. 2. The conductor duct is formed integrally with the conductor duct so as to protrude from the inner peripheral surface of the tube wall of the conductor duct toward the internal space of the conductor duct, and the outer periphery of the tube wall of the conductor duct 2. The cooling device having an electromagnetic shielding function according to claim 1, wherein the surface is disposed so as to cover the electronic device element and contact the electronic device element so as to receive heat conduction. 3. The conductor duct has openings at both ends, one end of which is arranged apart from the electronic device element, and the other end of which opens around the electronic device element including the heat dissipation element. The cooling device having an electromagnetic shielding function according to claim 1, wherein the cooling device is externally provided. 4. The opening of the conductor duct is dimensioned so as to block the emission of harmonic components radiated from an electronic device element from the opening.
A cooling device having the electromagnetic shielding function described in the above. 5. The cooling device having an electromagnetic shielding function according to claim 1, wherein an outer surface of the conductor duct is covered with a film formed of any one of a high dielectric loss material and a soft magnetic material. 6. The cooling device having an electromagnetic shielding function according to claim 1, further comprising an electric fan for generating an air flow circulating between the inner space and the outer space of the conductor duct through the opening. . 7. The cooling device having an electromagnetic shielding function according to claim 6, wherein a surface layer constituting at least the outer surface of the electric fan is formed of one of a high dielectric loss material and a soft magnetic material. 8. The cooling device having an electromagnetic shielding function according to claim 1, wherein the heat radiating element is constituted by one or more heat radiating fins.