COOLING DEVICE, AND ELECTRONIC APPARATUS WITH THE COOLING DEVICE
According to one embodiment, a cooling device is provided with a heat receiving member connected to a heat generator, a heat pipe connected to the heat receiving member, a heat dissipation fin connected to the heat pipe at an opposite side of the heat receiving member, and a fan configured to cool the heat dissipation fin. The cooling device is also provided with a tank containing a liquid and thermally connected to the heat receiving member.
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-262294, filed Nov. 30, 2012, the entire contents of which are incorporated herein by reference.
FIELDEmbodiments described herein relate generally to cooling devices using heat pipes, and electronic apparatuses with the cooling devices.
BACKGROUNDSome portable electronic apparatuses, such as note PCs, are provided with a cooling device for cooling a heat emitting component, such as a CPU. It is known that cooling devices of this type include those using a heat pipe. The heat pipe has one end thereof thermally connected to a heat generation component, and the other end thereof thermally connected to a heat dissipation component, such as a fin. The liquid in the heat pipe receives heat from the heat generation component to be evaporated at the one end of the pipe, and the resultant gas is cooled to be re-liquidized at the other end. The liquid obtained at the other end is returned to the one end. Thus, circulation is performed in the heat pipe.
When such a heat pipe as the above is used, if an electronic device is constructed such that its heat generation component is at a vertically higher position than its heat dissipation component (i.e., if the electronic device is in a top heat state), it is difficult to upwardly move a liquidized coolant to the heat generation component against the gravity. A cooling device, which has been developed in light of this to include two heat pipes extending from a heat generation component in different directions, is known.
Although this cooling device exhibits enhanced cooling performance, it is too large and too heavy.
Under the above circumstances, there is a demand for development of a small and light cooling device that can exert constant cooling performance regardless of the condition of use, and for an electronic device with such a cooling device.
A general architecture that implements the various features of the embodiments will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate the embodiments and not to limit the scope of the invention.
Various embodiments will be described hereinafter with reference to the accompanying drawings.
In general, according to one embodiment, a cooling device is provided with a heat receiving member connected to a heat generator; a heat pipe connected to the heat receiving member; a heat dissipation fin connected to the heat pipe at an opposite side of the heat receiving member; and a fan configured to cool the heat dissipation fin. The cooling device is also provided with a tank containing a liquid and thermally connected to the heat receiving member.
The tablet PC 100 comprises a display unit 105 that is located at its front side and is provided with a touch panel 106 through which an input operation using a touch pen 104 is possible. The touch pen 104 is provided so that it can be housed in the housing of the tablet PC 100.
The tablet PC 100 further comprises a circuit board 108, a battery 110, a camera module 111, a loudspeaker 112, a memory device 114, a cooling device 10, etc., as shown in
As shown in
As shown, the cooling device 10 comprises a heat receiving plate 2 (heat receiving member) attached to the circuit board 108, directly urged against the surface of a heat generator 5 (see
On the surface of the heat receiving plate 2 away from the heat generator 5 is thermally connected to one end 4a of a heat pipe 4. In the first embodiment, the heat pipe 4 is fixed to the heat receiving plate 2 by solder excellent in heat conductance. As shown in the cross section of
The heat pipe 4 contains water and the interior of the heat pipe is kept under negative pressure. The interior of the heat pipe 4 may contain a thin line or a wick for moving the liquid toward the one end 4a utilizing capillary phenomenon. If the heat pipe 4 is much thinned, the wick or thin line cannot be contained in the pipe. However, the wick is not indispensable element for the invention. The invention is also applicable to a cooling device using a heat pipe that is too thin to contain the wick.
A heat dissipation fin unit 6 is thermally connected to the other end 4b of the heat pipe 4. The heat dissipation fin unit 6 has a structure in which a plurality of plate-like fins are stacked with gaps defined therebetween. The heat dissipation fin unit 6 opposes the above-mentioned exhaust ports 103 of the housing 102. More specifically, the gaps of the plate-like fins oppose openings of the exhaust ports 103. In other words, the heat pipe 4 is angled in an L-shape to enable the heat dissipation fin unit 6 to oppose the exhaust ports 103.
A fan 8 that blows wind for cooling the heat dissipation fin unit 6 is attached to the opposite side of the heat dissipation fin unit 6 with respect to the exhaust ports 103. Namely, the wind of the fan 8 is exhausted through the exhaust ports 103 after passing through the plate-like fins of the heat dissipation fin unit 6. At this time, the fins of the heat dissipation fin unit 6 are cooled by the wind. A suction port 8a is formed through the fan 8 from the front side to the rear side thereof.
A tank 1 containing a liquid L (water in the first embodiment) is thermally connected to the surface of the heat receiving plate 2. In the first embodiment, the tank 1 is fixed to the heat receiving plate 2 using solder of a high heat conductivity. The interior of the tank 1 is kept under atmospheric pressure, and the liquid L occupies substantially half the volume of the tank 1. A detailed description will be given later of the appropriate liquid intake capacity of the tank 1.
As shown in the cross sectional view of
Further, to enhance the thermal transmission efficiency of the cooling device 10, the tank 1, the heat receiving plate 2 and the heat pipe 4 are formed of cooper that has a high heat transmission efficiency. Further, in the embodiment, the tank 1 is fixed to the heat receiving plate 2, after it is positioned so that the heat receiving plate 2 can be made in contact with the tank 1 with as a large area as possible.
Referring mainly to
The tablet PC 100 of the first embodiment is mainly used in the landscape mode, i.e., it is mainly operated in the attitude shown in
When the tablet PC is used in the landscape mode that is assumed most frequently, the cooling device 10 assumes the attitude shown in
In this state, the heat of the heat generator 5 is transmitted to one end 4a of the heat pipe 4 via the heat receiving plate 2 to thereby heat the liquid in the heat pipe 4. The gas resulting from evaporation of the liquid by the heat passes through the heat pipe 4 to the other end 4b, where it is cooled and re-liquidized by the heat dissipation fin unit 6. The resultant liquid flows downward through the heat pipe 4 due to gravity and returns to the end 4a of the heat pipe 4. Thus, in accordance with transmission of heat, coolant of a liquid phase or gas phase circulates in the heat pipe 4, thereby effectively cooling the heat generator 5.
In this state, the liquid L in the tank 1 attached to the heat receiving plate 2 pools in the lower portion of the tank 1 as shown in the enlarged view of
In contrast, when the tablet PC 100 is set in the inverted landscape mode shown in
If the tablet PC 100 is used in this state, it is difficult for the liquid, which results from cooling by the heat dissipation fin unit 6 at the other end 4b of the heat pipe 4, to upwardly flow in the heat pipe 4 against the gravity. In particular, if the cooling device 10 is made too thin to encapsulate, for example, a wick in the heat pipe 4, little liquid moves to the end 4a of the heat pipe 4, whereby the heat pipe 4 will easily assume a dry-out state. If this state is not eliminated, the capacity of the cooling device 10 for cooling the heat generator 5 may significantly reduce.
In the first embodiment, in such a inversed landscape mode as the above, the liquid L in the tank 1 attached to the heat receiving plate 2 moves and overlaps with the heat receiving plate 2 (i.e., the liquid surface becomes higher than the upper end of the heat receiving plate 2), with the result that part of the heat of the heat receiving plate 2 is transmitted to the liquid L. The heat transmission continues until the temperature of the liquid L is saturated. In other words, in the first embodiment, the amount of the liquid L in the tank 1, the attachment position of the tank 1 with respect to the heat receiving plate 2, etc., are set so that the liquid L can overlap with the heat receiving plate 2 with as a large area as possible at least in the top heat state. It is further preferable that the amount of the liquid L in the tank 1 should be set such that the liquid L in the tank 1 does not overlap with the heat receiving plate 2 when the cooling device 10 assumes the attitude shown in
Namely, in the first embodiment, by attaching the tank 1 to the heat receiving plate 2, reduction of the cooling function of the cooling device 10 can be retarded in the top heat state (shown in
Since in the first embodiment, the tank 1 is attached closer to the suction port 8a of the fan 8 than to the heat pipe 4, the liquid L in the tank 1 can also be cooled, which can relatively increase the period of suppression effect of the performance reduction at the top heat time.
Also, since the first embodiment employs a structure in which the tank 1 containing the liquid L is attached to the heat receiving plate 2, the whole device can be prevented from being increased in size and from being significantly increased in weight, whereby the whole device can be manufactured at relatively low cost.
If the liquid L in the tank 1 is water, and a copper body having a high heat conductivity is attached to the heat receiving plate 2 in place of the tank 1, the volume of copper having the same heat capacity as the tank 1 will be ten times or more the volume of the tank 1, since the specific heat of water is 4.2 J/gK and that of copper is 0.379 J/gK. In this case, since weight percent of water is 0.99 and that of copper is 8.82, if the copper body is attached instead of tank 1, the resultant weight will be about 8 times heavier than in the case where the tank 1 is attached. Namely, by employing the apparatus structure of the embodiment where the tank 1 containing the liquid L is attached to the heat receiving plate 2, the cooling device 10 can be made small and light.
Referring then to
As shown in
When a tablet PC 100 provided with the cooling device 20 is used in a landscape mode in which the tablet PC assumes the attitude shown in
In contrast, when the tablet PC 100 of the attitude shown in
Further, when the tablet PC with the cooling device 20 is used in the portrait mode shown in
In contrast, when the tablet PC 100 of the attitude shown in
In other words, the tank 1 is attached to the heat receiving plate 21, such that when the portion (first portion) of the heat pipe 4 between the end 4a connected to the heat receiving plate 21 and the angled portion 4c of the (L-shaped) heat pipe 4 is positioned vertically, and the end 4b of the heat pipe 4 connected to the heat dissipation fin unit 6 is positioned gravitationally above the end 4a (i.e., when the cooling device is in the attitude shown in
Namely, in the second embodiment, when the tablet PC is used in the landscape mode shown in
Referring then to
The heat receiving plate 31 of the cooling device 30 is slightly longer than the heat receiving plate 2 of the first embodiment. Namely, in order to arrange the tank 1 on the backside of the heat receiving plate 31 kept in contact with the heat generator 5, the heat receiving plate 31 is elongated along the heat generator 5 and the tank 1 that are located in line.
When the tablet PC 100 with the cooling device 30 is used, placed on, for example, a desk with the touch panel 105 directed upward, the liquid L in the tank 1 of the cooling device 30 pools in the lower portion of the tank and is away from the heat receiving plate 31 as shown in
Also when the tablet PC 100 with the cooling device 30 is used in the landscape mode (shown in
Further, when the tablet PC 100 with the cooling device 30 is used in such an inverted landscape mode as shown in
Thus, the cooling device 30 of the third embodiment can provide the same advantage as the cooling device 10 of the first embodiment, and the liquid L in the tank 1 can be prevented from being heated when, for example, the tablet PC is used, placed on a desk.
In the cooling device according to at least one of the above-described embodiments, since the tank 1 containing the liquid L is kept in thermal contact with a heat receiving plate connected to a heat generator, the cooling device can have a constant cooling performance regardless of the attitude (state of use) of an electronic device with the cooling device.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
For instance, although in the above-described embodiments, the invention is applied to the cooling device of a tablet PC as an example of an electronic apparatus, it may also be applicable to another type of electronic apparatus, such as a note PC and a cellular phone.
Claims
1. A cooling device comprising:
- a heat receiving member connected to a heat generator;
- a heat pipe connected to the heat receiving member;
- a heat dissipation fin connected to the heat pipe at an opposite side of the heat receiving member;
- a fan configured to cool the heat dissipation fin; and
- a tank containing a liquid and thermally connected to the heat receiving member.
2. The cooling device of claim 1, wherein when an end of the heat pipe connected to the heat receiving member is positioned gravitationally above another end of the heat pipe connected to the heat dissipation fin, the liquid in the tank overlaps with the heat receiving member.
3. The cooling device of claim 2, wherein when the end of the heat pipe connected to the heat receiving member is positioned gravitationally below the another end of the heat pipe connected to the heat dissipation fin, the liquid in the tank does not overlap with the heat receiving member.
4. The cooling device of claim 1, wherein the tank is located closer to a suction port of the fan than the heat pipe.
5. The cooling device of claim 1, wherein
- the heat pipe is angled in an L shape; and
- the tank is attached to the heat receiving member in a positional relationship in which the liquid in the tank does not overlap with the heat receiving member when a first portion of the heat pipe between the end of the heat pipe and an angled portion of the heat pipe extends vertically and the another end of the heat pipe connected to the fin is positioned gravitationally above the end of the heat pipe, and when a second portion between the angled portion of the heat pipe and the another end of the heat pipe extends vertically and the another end of the heat pipe is positioned gravitationally above the end of the heat pipe.
6. The cooling device of claim 1, wherein the tank is attached to the heat receiving member by solder.
7. An electronic apparatus comprising:
- a housing with an exhaust port;
- a heat generator in the housing; and
- a cooling device attached to the heat generator,
- wherein
- the cooling device comprises:
- a heat receiving member connected to the heat generator;
- a heat pipe connected to the heat receiving member;
- a heat dissipation fin connected to the heat pipe at an opposite side of the heat receiving member, and opposing an inside of the exhaust port;
- a fan located near the exhaust port with the heat dissipation fin interposed therebetween, and configured to cool the heat dissipation fin; and
- a tank containing a liquid and thermally connected to the heat receiving member.
8. The electronic apparatus of claim 7, wherein when the housing assumes an attitude in which an end of the heat pipe connected to the heat receiving member is positioned gravitationally above another end of the heat pipe connected to the heat dissipation fin, the liquid in the tank overlaps with the heat receiving member.
9. The electronic apparatus of claim 7, wherein when the housing assumes an attitude in which the end of the heat pipe connected to the heat receiving member is positioned gravitationally below the another end of the heat pipe connected to the heat dissipation fin, the liquid in the tank does not overlap with the heat receiving member.
10. The electronic apparatus of claim 7, wherein the tank is located closer to a suction port of the fan than the heat pipe.
11. The electronic apparatus of claim 7, wherein
- the heat pipe is angled in an L shape; and
- the tank is attached to the heat receiving member in a positional relationship in which the liquid in the tank does not overlap with the heat receiving member when a first portion of the heat pipe between the end of the heat pipe and an angled portion of the heat pipe extends vertically and the another end of the heat pipe connected to the fin is positioned gravitationally above the end of the heat pipe, and when a second portion between the angled portion of the heat pipe and the another end of the heat pipe extends vertically and the another end of the heat pipe is positioned gravitationally above the end of the heat pipe.
12. The electronic apparatus of claim 7, wherein the tank is attached to the heat receiving member by solder.
Type: Application
Filed: Jun 18, 2013
Publication Date: Jun 5, 2014
Inventor: Yukihiko Hata (Hamura-shi)
Application Number: 13/920,931
International Classification: F28D 15/02 (20060101);