US20050022977A1

US20050022977A1 - Counter-stream-mode oscillating-flow heat transport apparatus

Info

Publication number: US20050022977A1
Application number: US10/866,003
Authority: US
Inventors: Kimio Kohara; Seiji Inoue; Kenichi Nara; Koji Fujiki; Katsuhiko Oka; Tomoki Naganawa
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2003-06-12
Filing date: 2004-06-11
Publication date: 2005-02-03
Also published as: JP2005140492A

Abstract

A counter-stream-mode oscillating-flow heat transport apparatus accommodates a change in volume of a liquid while preventing reduction in heat transport capability. A flow path and a buffer tank are placed in communication with each other via a throttle such as a capillary tube. This prevents a channel connecting the flow path and the buffer tank from having an excessively reduced channel resistance (flow path resistance). This prevents the fluid in a heat transport device assembly (the flow path) from only going back and forth between the heat transport device assembly and the buffer tank without experiencing liquid (pressure) oscillations in the heat transport device assembly. Accordingly, the liquid in the heat transport device assembly is prevented from being reduced in amplitude of oscillation, thereby preventing degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon, claims the benefit of priority of, and incorporates by reference Japanese Patent Applications No. 2003-167746 filed Jun. 12, 2003, No. 2003-356304 filed Oct. 16, 2003, and No. 2004-118910 filed Apr. 14, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a counter-stream-mode oscillating-flow heat transport apparatus that induces oscillatory movement in a liquid flowing in opposite directions through adjacent flow paths to transfer heat therebetween and thereby transport heat from a hot area to a cold area. The apparatus is effectively applicable to thermal-quasi-superconductive plates, thermal switches, thermal diodes, and the like.
2. Description of the Related Art
The counter-stream-mode oscillating-flow heat transport apparatus utilizes the enhanced diffusion effect provided by oscillatory movement in a fluid flow based on the following principle.
Take an example shown in FIG. 21, in which a liquid within a conduit has a temperature distribution. For simplicity, consider a rectangular wave oscillation induced in the liquid, in the case of which a portion of the liquid stays at point H for half an oscillation cycle and then immediately moves to point L and stays there for the other half cycle, then moves back again to point H immediately thereafter.
Consider a liquid portion (referred to as an element) at point C in the absence of oscillation. When this element is oscillated to move to point H, heat is transferred from the wall of the conduit to the element because the temperature of the wall at point H is higher than that of the element. When the element is further oscillated to move to point L, heat is transferred from the element to the wall because the temperature of the wall at point L is lower than that of the element.
In other words, one oscillation causes heat to be transferred from point H to point L just as a frog jumps from one place to another. Such a frog jump would never occur in the absence of the oscillation but is caused to take place by the oscillation. Thus, the higher the frequency of the oscillation, the larger the number of times of frog jumps per unit time becomes, while the larger the amplitude, the greater the distance of a frog jump becomes. That is, the additional displacement of heat provided by a frog jump increases with increasing amplitudes and cycles (e.g., see Patent Document 1, or Japanese Patent Laid-Open Publication No. 2002-364991)
A liquid within in a heat transport device that provides a flow path varies in volume due to changes in temperature or a trace amount of leakage. Accordingly, when the liquid expands in volume due to an increase in temperature, it is necessary to accommodate the increase in volume and thus an increase in pressure, to prevent damage to the heat transport device assembly.
On the other hand, when a decrease in volume of the liquid, due to a decrease in temperature, reduces the pressure in the heat transport device, the decrease in pressure results in a gas being produced in the heat transport device. The resulting gas absorbs oscillatory movement in the liquid to reduce the amplitude of the oscillatory movement in the liquid, thereby causing a decrease in heat transport capability. It is thus necessary to accommodate a reduction in volume of the liquid to prevent degradation in heat transport capability.
To this end, the flow path in the heat transport device may be placed in communication with a buffer tank such as a reserve tank. With this configuration, when the liquid in the flow path is expanded, the excessive volume of liquid resulting from the expansion can be introduced into the buffer tank to accommodate the expansion in volume. On the other hand, when the liquid in the flow path is contracted to decrease in volume, the reduced amount of liquid resulting from the contraction can be supplied from the buffer tank to the flow path, thereby accommodating the contraction in volume.
However, since liquid (pressure) oscillations occur everywhere in the flow path, an excessively low channel resistance (flow path resistance) across the channel for connecting between the flow path and the buffer tank would cause the liquid to move only back and forth between the flow path and the buffer tank without experiencing any liquid (pressure) oscillation in the flow path (in the heat transport device). This may cause the liquid in the flow path (in the heat transport device) to be reduced in oscillation amplitude, resulting in a decrease in heat transport capability.

SUMMARY OF THE INVENTION

The present invention was developed in view of the aforementioned problems. It is therefore a first object of the invention to provide a new counter-stream-mode oscillating-flow heat transport apparatus that is different from the prior art. A second object of the invention is to provide a counter-stream-mode oscillating-flow heat transport apparatus that accommodates changes in volume of a liquid while preventing degradation in heat transport capability.
To achieve the aforementioned objects, a first aspect of the invention offers a counter-stream-mode oscillating-flow heat transport apparatus for inducing oscillatory movement in a liquid flowing in opposite directions through adjacent flow paths (3) to transfer heat between the adjacent flow paths (3) and thereby transport heat from a hot area to a cold area. The apparatus has a buffer tank (6) that is placed in communication with the flow path (3) and accommodates changes in volume of the liquid, such that the flow path (3) and the buffer tank (6) communicate with each other via throttle means having a predetermined channel resistance.
This feature prevents a channel connecting between the flow path (3) and the buffer tank (6) from having an excessively reduced channel resistance (flow path resistance), thereby preventing the liquid in the flow path (3) from only going back and forth between the flow path (3) and the buffer tank (6) due to oscillations in the liquid. Accordingly, the liquid in the flow path (3) is prevented from being reduced in amplitude of oscillation, thereby preventing degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus.
A second aspect of the invention is characterized in that the throttle means (5) includes a capillary tube having a channel of a predetermined length. A third aspect of the invention is characterized in that the throttle means (5) includes an orifice having a hole of a predetermined diameter.
A fourth aspect of the invention is characterized in that the throttle means (5) includes liquid channel means formed in a scroll pattern.
These features allow the throttle means (5) to be reduced in size while ensuring a required length of the liquid channel included in the throttle means (5), thereby preventing the counter-stream-mode oscillating-flow heat transport apparatus from increasing in size. At the same time, the features also prevent the channel connecting between the flow path (3) and the buffer tank (6) from having an excessively reduced channel resistance (flow path resistance), thereby preventing degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus.
These features also allow for elongating the length of the liquid channel to thereby ensure a required channel resistance (flow path resistance). This allows for making the liquid channel more resistant to clogging as compared with a case where the channel resistance is provided by the liquid channel being reduced in cross section, thereby providing higher reliability for the counter-stream-mode oscillating-flow heat transport apparatus.
A fifth aspect of the invention is characterized in that the liquid channel means has a plate (5 a) having a groove (5 b) formed in a scroll pattern. A sixth aspect of the invention is characterized in that the throttle means (5) has liquid channel means formed in a spiral fashion. These features allow the throttle means (5) to be reduced in size while ensuring a required length of the liquid channel included in the throttle means (5), thereby preventing the counter-stream-mode oscillating-flow heat transport apparatus from increasing in size. At the same time, the features also prevent the channel connecting between the flow path (3) and the buffer tank (6) from having an excessively reduced channel resistance (flow path resistance), thereby preventing degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus.
On the other hand, these features also allow for elongating the length of the liquid channel to thereby ensure a required channel resistance (flow path resistance). This allows for making the liquid channel more resistant to clogging as compared with a case where the channel resistance is provided by the liquid channel being reduced in cross section, thereby providing higher reliability for the counter-stream-mode oscillating-flow heat transport apparatus.
A seventh aspect of the invention is characterized in that the liquid channel means has a female screw-shaped member (5 c) having a spiral groove (5 b) formed on an inner circumferential wall thereof and a rod-shaped cover member (5 d) fitted into the female screw-shaped member (5 c). An eighth aspect of the invention is characterized in that the liquid channel means has a male screw-shaped member (5 e) having a spiral groove (5 b) formed on an outer circumferential wall thereof and a cylindrical member (5 g) having a hole portion (5 f) fitted over the male screw-shaped member (5 e). A ninth aspect of the invention is characterized such that the groove (5 b) is generally triangular in cross section. A tenth aspect of the invention is characterized such that the throttle means (5) is in communication with a tank chamber (6 a) in the buffer tank (6), the tank chamber (6 a) being filled with a fluid and changeable in volume.
A tenth aspect of the invention is characterized such that the buffer tank (6) has the tank chamber (6 a) filled with a liquid and a gas tank chamber (6 d) filled with a gas, wherein a partition (6 b, 6 f) for defining the tank chamber (6 a) and the gas tank chamber (6 d) is elastically deformable and displaceable.
A twelfth aspect of the invention is characterized such that the partition (6 b) has a bellows. A thirteenth aspect of the invention is characterized such that the partition (6 f) is formed of a bag-shaped thin-film member of an elastic material. A fourteenth aspect of the invention is characterized such that the buffer tank (6) is filled with a liquid and a gas, and has opening position correction means for positioning a buffer tank (6) side opening of the throttle means (5) below the interface between the liquid and the gas. These features allow for accommodating changes in volume of the liquid while preventing the buffer tank (6) from being installed in a limited orientation (in the vertical direction), thereby preventing degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus.
A fifteenth aspect of the invention, which is based on the counter-stream-mode oscillating-flow heat transport apparatus according to the first aspect, is characterized such that the buffer tank (6) is located in the liquid and formed in the shape of a capsule having a space therein. The throttle means (5) is integrated with the buffer tank (6), the buffer tank (6) having a gas and a liquid filled in the inner space and including a weight portion (6 h, 9, 10 b) for orienting a tank inner opening (5 h) of the throttle means (5) such that the tank inner opening (5 h) is immersed in the liquid.
This feature allows the weight portion (6 h, 9, 10 b) to orient the tank inner opening (5 h) such that the tank inner opening (5 h) is immersed in the liquid irrespective of the orientation in which the counter-stream-mode oscillating-flow heat transport apparatus is installed. Accordingly, an increase in volume of the liquid would cause the gas in the buffer tank (6) to be compressed, thereby accommodating the increase in volume of the liquid. On the other hand, a decrease in volume of the liquid would cause the liquid in the buffer tank (6) to flow into the flow path (3), thereby preventing the decrease in volume of the liquid. The apparatus can make use of these effects without having a movable or elastic portion susceptible to changes over time, thereby providing enhanced durability.
A sixteenth aspect of the invention, which is based on the counter-stream-mode oscillating-flow heat transport apparatus according to the fifteenth aspect, has a female screw portion (6 i) formed in the buffer tank (6) and a bolt-shaped member (10) integrated with a male screw portion (10 a) screwed into the female screw portion (6 i) and the weight portion (10 b). This is accomplished such that the throttle means (5) passes through the male screw portion (10 a) and the weight portion (10 b). This feature allows the buffer tank (6) to be easily integrated with the throttle means (5) and the weight portion (10 b) by the male screw portion (10 a) of the bolt-shaped member (10) being screwed into the female screw portion (6 i) of the buffer tank (6).
According to a seventeenth aspect of the invention, the throttle means (5) of the counter-stream-mode oscillating-flow heat transport apparatus incorporating any of the second to ninth aspects may be used to form the throttle means (5) of the buffer tank (6).
According to an eighteenth aspect of the invention, the counter-stream-mode oscillating-flow heat transport apparatus incorporating any of the fifteenth to seventeenth aspects may include a reserve tank (8) provided with a communication path (7) in communication with the flow path (3) and filled with the liquid therein, such that the buffer tank (6) is located inside the reserve tank (8). According to a nineteenth aspect of the invention, the counter-stream-mode oscillating-flow heat transport apparatus that incorporates the eighteenth aspect of the invention may include a plurality of the buffer tanks (6) located in the reserve tank (8).
According to a twentieth aspect of the invention, the counter-stream-mode oscillating-flow heat transport apparatus incorporating the eighteenth or nineteenth aspect may include a plurality of the communication paths (7), thereby preventing the buffer tank (6) from blocking the communication paths. According to a twenty-first aspect of the invention, the counter-stream-mode oscillating-flow heat transport apparatus according to any one of fifteenth to twentieth aspects may include the buffer tank (6) formed generally in a spherical shape, thereby ensuring that the weight portion (6 h, 9, 10 b) quickly orients the tank inner opening (5 h) of the throttle means (5) such that the tank inner opening (5 h) is immersed in the liquid.
According to a twenty-second aspect of the invention, the counter-stream-mode oscillating-flow heat transport apparatus according to any one of the fifteenth to twenty-first aspects may have the weight portion formed of a fixing material (9) for securing the throttle means (5) to the buffer tank (6), thereby allowing the throttle means (5) to be secured to the buffer tank (6) and the weight portion to be secured to the buffer tank (6) at the same time. A twenty-third aspect is characterized in that the channel resistance across the throttle means (5) is from 0.1% to 5% of the channel resistance across the flow path (3). According to a twenty-fourth aspect, the channel resistance across the throttle means (5) is from 0.5% to 3% of the channel resistance across the flow path (3).
Incidentally, the parenthesized numerals accompanying the foregoing individual means correspondence with concrete means seen in the embodiments to be described later. Additionally, further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
FIG. 1 is a schematic view of a counter-stream-mode oscillating-flow heat transport apparatus according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view of a buffer tank according to a first embodiment of the present invention;
FIG. 3 is a cross-sectional view of a buffer tank according to a second embodiment of the present invention;
FIG. 4 is a cross-sectional view of a buffer tank according to a third embodiment of the present invention;
FIG. 5 is a cross-sectional view of a buffer tank according to a fourth embodiment of the present invention;
FIG. 6 is a cross-sectional view of a buffer tank according to a fifth embodiment of the present invention;
FIGS. 7A is a view of a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a sixth embodiment of the present invention;
FIGS. 7B is a cross-sectional view of a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a sixth embodiment of the present invention;
FIG. 8 is a cross-sectional view of a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to the sixth embodiment of the present invention;
FIG. 9A is a cross-sectional view of a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a seventh embodiment of the present invention;
FIG. 9B is an enlarged cross-sectional view of a portion of FIG. 9A;
FIG. 10 is a cross-sectional view of a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a seventh embodiment of the present invention;
FIG. 11 is a view showing a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a modified example of the seventh embodiment of the present invention;
FIG. 12 is a cross-sectional view showing the feature of a counter-stream-mode oscillating-flow heat transport apparatus according to an eighth embodiment of the present invention;
FIG. 13 is a partial cross-sectional view showing a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a ninth embodiment of the present invention;
FIG. 14A is a cross-sectional view of a feature of a counter-stream-mode oscillating-flow heat transport apparatus installed in a particular orientation according to a tenth embodiment of the present invention;
FIG. 14B is a cross-sectional view of a feature of a counter-stream-mode oscillating-flow heat transport apparatus installed in a particular orientation according to a tenth embodiment of the present invention;
FIG. 15 is a cross-sectional view showing a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to an eleventh embodiment of the present invention;
FIG. 16 is a cross-sectional view showing a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a twelfth embodiment of the present invention;
FIG. 17 is a cross-sectional view showing a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a thirteenth embodiment of the present invention;
FIG. 18 is a cross-sectional view showing a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a fourteenth embodiment of the present invention;
FIG. 19 is a cross-sectional view showing a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a fifteenth embodiment of the present invention;
FIG. 20 is a cross-sectional view showing a feature of a counter-stream-mode oscillating-flow heat transport apparatus according to a sixteenth embodiment of the present invention; and
FIG. 21 is an explanatory view showing the operation of a counter-stream-mode oscillating-flow heat transport apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
[First Embodiment]
This embodiment is implemented by the present invention being applied to a cooling device for use with electronic components. FIG. 1 is a schematic view showing a counter-stream-mode oscillating-flow heat transport apparatus 1 according to this embodiment. FIG. 2 is a partially enlarged cross-sectional view showing a buffer tank 6.
Referring to FIG. 1, a heat transport device assembly 2 formed generally in the shape of a swath of plate has meandering flow paths 3 filled with a liquid, and includes a target to be cooled or a heating element (not shown) with a heat source on a plate face generally at a longitudinal end (at the upper end in the figure). The configuration of the heat transport device assembly 2 will be described later.
In this embodiment, the heating element is intended to represent electronic components such as integrated circuits for use in computers. The heat transport device assembly 2 is also provided with a heat sink (not shown) on the plate face opposite to that on which the heating element is provided. The heat sink has a plurality of heat-radiating thin-plate fins for radiating heat transported from the heating element (hot side) to the atmosphere (cold side).
An oscillator 4 serves as a pumping means for inducing oscillations in the liquid within the heat transport device assembly 2. The oscillator 4 works as a vibrator for oscillating a liquid, e.g., by reciprocating a plunger integrated with a movable element displaced by electromagnetic force and a piston for inducing oscillations in the liquid.
This embodiment employs water as a liquid filled in the flow paths 3; however, it is also possible to employ such water that is mixed with an additive for preventing corrosion of metal or reducing the viscosity of liquid or with an antifreeze such as ethylene glycol for preventing of freezing. The heat transport device assembly 2 according to this embodiment has a plurality of meandering flow paths 3, which are formed therein as follows. That is, metal plates such as of copper or aluminum having a high thermal conductivity are first etched to form meandering grooves thereon, and the resulting plates are then stacked in the direction of their thickness to be joined together by brazing or by thermal compression.
A flow path 3 near the oscillator 4 is in communication with the buffer tank 6 via a capillary tube 5 included in the throttle means having a predetermined channel resistance. FIG. 1 shows the capillary tube 5 included in the throttle means in the form that conforms to JIS B 0125 No. 2-3.7; however, the throttle means includes a thin tube having a predetermined channel length as shown in FIG. 2.
As shown in FIG. 2, the buffer tank 6 includes a bellows 6 b defining a liquid tank chamber 6 a, which is filled with a liquid and changeable in volume, and a cover 6 c for surrounding the bellows 6 b to protect the bellows 6 b or the buffer tank 6. The cover 6 c is preferably provided with a hole 6 h that serves to prevent a closed space from being formed outside the liquid tank chamber 6 a. This embodiment has the bellows 6 b made of a stainless steel alloy and allows the cover 6 c to work as a stopper for limiting the maximum displacement of the bellows 6 b, i.e., the maximum volume of the liquid tank chamber 6 a.
Suppose that the temperature of the liquid changes from 0° C. to 80° C. In this case, the liquid increases in volume by several percent (about 3% for water or about 4% for water mixed with an antifreeze such as ethylene glycol). Accordingly, this embodiment is designed such that the bellows 6 b is 26 mm in its outer dimensions and allowed to displace 12 mm at the maximum.
Now, the operation of the counter-stream-mode oscillating-flow heat transport apparatus 1 according to this embodiment will be generally explained. Oscillations being induced in the liquid in the flow paths 3 (the heat transport device assembly 2) by the oscillator 4 allow heat to be transferred between the liquid flowing through adjacent flow paths 3. This causes heat from the heating element located at one longitudinal end of the heat transport device assembly 2 to be transported toward the other longitudinal end of the heat transport device assembly 2, thus spreading the heat throughout the heat transport device assembly 2. The heat thus spread throughout the heat transport device assembly 2 and collected at the other longitudinal end thereof is released into the atmosphere via the heat sink.
Now, the operation and effects of the buffer tank 6 will be described. Suppose that the liquid in the heat transport device assembly 2 (the f low paths 3) is expanded by a certain amount of volume. This volume of liquid flows into the buffer tank 6 (the liquid tank chamber 6 a) via the capillary tube 5, thereby accommodating the expansion in volume of the liquid flowing through the heat transport device assembly 2.
On the other hand, when the liquid flowing through the heat transport device assembly 2 (the flow paths 3) is reduced in volume, the liquid in the buffer tank 6 (the liquid tank chamber 6 a) flows back into the heat transport device assembly 2 via the capillary tube 5, thereby accommodating the reduction in volume of the liquid.
At this time, since the heat transport device assembly 2 (the flow path 3) and the buffer tank 6 are in communication with each other via the capillary tube 5 that has a predetermined channel resistance, the channel connecting the flow path 3 and the buffer tank 6 will never have an excessively reduced channel resistance (flow path resistance).
Therefore, the liquid in the heat transport device assembly 2 (the flow path 3) can be prevented from moving only back and forth between the heat transport device assembly 2 and the buffer tank 6 without experiencing any liquid (pressure) oscillation in the heat transport device assembly 2. It is thus possible to prevent the liquid in the heat transport device assembly 2 from being reduced in oscillation amplitude as well as the counter-stream-mode oscillating-flow heat transport apparatus 1 from being reduced in heat transport capability.
As can be seen from the aforementioned description on the operation, the liquid tank chamber 6 a and the heat transport device assembly 2 are preferably filled with a liquid. That is, the liquid tank chamber 6 a and the flow path 3 may be first evacuated using a vacuum pump or the like allowing no gas to remain in the liquid tank chamber 6 a and the flow path 3, and thereafter a liquid (water in this embodiment) may be injected therein.
An excessively high channel resistance across the capillary tube 5 would make it impossible to quickly supply the liquid from the buffer tank 6 to the heat transport device assembly 2 when the liquid is reduced in volume. Therefore, the channel resistance across the capillary tube included in the throttle means is from 0.1% to 5%, preferably from 0.5% to 3% of the channel resistance across the flow path 3. In this context, this embodiment is adapted such that the length of the capillary tube 5 is 30 mm and the hole in the capillary tube 5 is 0.12 mm to 0.19 mm in diameter, thereby providing the capillary tube 5 with a channel resistance which is from 0.5% to 3% of the channel resistance across the flow path 3.
The channel resistance across the throttle means or the channel resistance across the capillary tube 5 and the channel resistance across the flow path 3 refer to a pressure loss produced by a reference liquid (water in this embodiment) being allowed to flow at a predetermined flow rate. The channel resistance across the capillary tube 5 can be adjusted to an appropriate value, thereby preventing the liquid in the buffer tank 6 from resonating with vibrations created by the oscillator 4. This in turn makes it possible to prevent the occurrence of oscillatory noise and damage otherwise caused by the resonance.
[Second Embodiment]
In the first embodiment, the space in the bellows 6 b was employed as the liquid tank chamber 6 a. However, as shown in FIG. 3, this embodiment is adapted such that the buffer tank 6 includes a liquid tank chamber 6 a filled with a liquid and a gas tank chamber 6 d filled with a gas. Also employed is a bellows 6 b, which is elastically deformable and displaceable, as a partition for defining the liquid tank chamber 6 a and the gas tank chamber 6 d.
In this second embodiment, the space defined by the bellows 6 b and a cylindrical housing 6 e serves as the liquid tank chamber 6 a, while the space in the bellows 6 b serves as the gas tank chamber 6 d. Since the gas tank chamber 6 d is a closed space in this embodiment, a gas to be sealed in the gas tank chamber 6 d is preferably an inert gas such as nitrogen. However, to provide a hole 6 h for the gas tank chamber 6 d to define an open space, the buffer tank 6 is configured substantially in the same manner as in the first embodiment.
[Third Embodiment]
This embodiment is a modified example of the second embodiment. More specifically, as shown in FIG. 4, a partitioning member for defining the liquid tank chamber 6 a and the gas tank chamber 6 d is a thin-film bag-shaped member 6 f made of an elastic material such as rubber. In this embodiment, the space defined by the bag-shaped member 6 f and the housing 6 e serves as the liquid tank chamber 6 a, while the closed space in the bag-shaped member 6 f serves as the gas tank chamber 6 d.
[Fourth Embodiment]
In this embodiment, as shown in FIG. 5, the buffer tank 6 is filled with a liquid and a gas, and the capillary tube 5 is made of a flexible material as used for a rubber hose or the like. The capillary tube 5 is provided with a weight 6 g at an opening thereof at the buffer tank 6 side such that the buffer tank 6 side opening of the capillary tube 5 is always located below the interface between the liquid and the gas.
This feature allows for preventing the gas from flowing into the heat transport device assembly 2 (the flow path 3) irrespective of the orientation of installation of the buffer tank 6. The feature also allows for accommodating changes in volume of the liquid, thereby preventing degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus 1.
With the buffer tank 6 being sealed, it is preferable to employ a gas, such as nitrogen, which is hardly soluble in a liquid. However, the buffer tank 6 may also be defined as an open space. For example, suppose that the liquid (water in this embodiment) has a volume of 100 cc and the gas has a volume of 10 cc, and the liquid and the gas are sealed under atmospheric pressure (0.1 MPa). Since the maximum pressure is about 0.14 MPa in this case, the buffer tank 6 being formed as a closed tank would never be manufactured at significantly increased costs.
[Fifth Embodiment]
In this embodiment, as shown in FIG. 6, the capillary tube 5 is provided with the weight 6 g at the opening thereof at the buffer tank 6 side such that the buffer tank 6 side opening of the capillary tube 5 is always located below the interface between the liquid and the gas. In this embodiment, the capillary tube 5 is inserted into the buffer tank 6 so as to extend from top to bottom. It is thus not necessary to make the capillary tube 5 of a flexible material as used for a rubber hose or the like; nevertheless, the capillary tube 5 may be made of a flexible material.
[Sixth Embodiment]
The capillary tube 5 serving as the throttle means was formed in a straight line in the first to third embodiments; however, in this embodiment, the liquid channel serving as the throttle means is formed in a scroll pattern. That is, as shown in FIG. 7, this embodiment is designed such that a scroll-patterned groove 5 b is formed on a plate 5 a of metal or resin. Additionally, as shown in FIG. 8, the groove 5 b side of the plate 5 a is joined to the heat transport device assembly 2, thereby blocking the groove 5 b at the heat transport device assembly 2 to form the scroll-patterned liquid channel, i.e., the throttle means.
For example, the plate 5 a is secured to the heat transport device assembly 2 by bonding or brazing or with mechanical means such as a spring providing a spring-back force or a screw. Additionally, in this embodiment, the center portion of the scroll-patterned groove 5 b is placed in communication with the flow path 3 of the heat transport device assembly 2, while the end of the scroll-patterned groove 5 b is placed in communication with the inside of the liquid tank chamber 6 a.
These features allow for reducing the size of the plate 5 a having the groove 5 b formed thereon while ensuring a required length of the liquid channel serving as the throttle means or of the groove 5 b, thereby preventing the counter-stream-mode oscillating-flow heat transport apparatus 1 from increasing in size. At the same time, the features also prevent the channel connecting between the heat transport device assembly 2 (the flow path 3) and the buffer tank 6 from having an excessively reduced channel resistance (flow path resistance), thereby preventing degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus 1.
On the other hand, these features also allow for elongating the length of the liquid channel or the groove 5 b to thereby ensure a required channel resistance (flow path resistance). This allows for making the liquid channel more resistant to clogging as compared with a case where the channel resistance is provided by the liquid channel being reduced in cross section, thereby providing higher reliability for the counter-stream-mode oscillating-flow heat transport apparatus 1.
This embodiment can be implemented with the capillary tube 5 being formed in a scroll pattern. However, since it is more difficult to form the capillary tube 5 in a scroll pattern than to form the scroll-patterned groove 5 b on the plate 5 a, this embodiment is designed such that the scroll-patterned groove 5 b is engraved on the plate 5 a to form a scroll-patterned liquid channel or the throttle means. In this embodiment, the groove 5 b is generally triangular in cross section because the triangular cross section can be easily formed when the groove 5 b is engraved by cutting. Therefore, the groove 5 b according to this embodiment is not limited to a triangular shape, but may also be formed in a rectangular or semi-circular shape when the groove 5 b is formed using dies, e.g., by stamping or by injection molding.
In another way, in this embodiment, the opening side of the groove 5 b is blocked at the heat transport device assembly 2; however, this embodiment is not limited thereto, and the opening side of the groove 5 b may also be blocked with a specially prepared plate. Furthermore, the center portion of the scroll-patterned groove 5 b is placed in communication with the flow path 3 of the heat transport device assembly 2, while the end of the scroll-patterned groove 5 b is placed in communication with the inside of the liquid tank chamber 6 a; however, this embodiment is not limited thereto. In contrast to this, the center portion of the scroll-patterned groove 5 b may be placed in communication with the inside of the liquid tank chamber 6 a, with the end of the scroll-patterned groove 5 b being placed in communication with the flow path 3 of the heat transport device assembly 2.
[Seventh Embodiment]
Although the sixth embodiment employs the scroll-patterned liquid channel serving as the throttle means, this embodiment employs a spiral liquid channel serving as the throttle means. That is, as shown in FIGS. 9A and 9B, a rod-shaped cover member 5 d is fitted into a female screw-shaped member 5 c, on the inner circumferential wall of which is formed a spiral groove 5 b, to block the opening side of the groove 5 b formed on the female screw-shaped member 5 c, thus forming a spiral liquid channel.
Like the sixth embodiment, this feature also allows this embodiment to reduce the size of the plate 5 a having the groove 5 b formed thereon while ensuring a required length of the liquid channel serving as the throttle means or of the groove 5 b, thereby preventing the counter-stream-mode oscillating-flow heat transport apparatus 1 from increasing in size. At the same time, the feature also prevents the channel connecting between the heat transport device assembly 2 (the flow path 3) and the buffer tank 6 from having an excessively reduced channel resistance (flow path resistance), thereby preventing degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus 1.
On the other hand, this feature also allows for elongating the length of the liquid channel or the groove 5 b to thereby ensure a required channel resistance (flow path resistance). This allows for making the liquid channel more resistant to clogging as compared with a case where the channel resistance is provided by the liquid channel being reduced in cross section, thereby providing higher reliability for the counter-stream-mode oscillating-flow heat transport apparatus 1.
Furthermore, the groove 5 b serving as the throttle means can be easily tapped, thereby readily providing the throttle means without an increase in manufacturing man-hours. As shown in FIG. 9, the cover member 5 d has a ridge diameter d that is smaller than the root diameter D of the female screw-shaped member 5 c. Alternatively, as shown in FIG. 10, the cover member 5 d may be formed in a simple cylindrical or tubular shape, which has the same diameter as the ridge diameter of the female screw-shaped member 5 c, so as to be securely fitted into the female screw-shaped member 5 c. The cover member 5 d can be made of any material such as resin or metal.
As shown in FIG. 11, in this embodiment, a communication hole formed in the heat transport device assembly 2 to communicate with the liquid tank chamber 6 a is employed as the female screw-shaped member 5 c, on the inner circumferential wall of which formed is the spiral groove 5 b; however, this embodiment is not limited thereto. Furthermore, in this embodiment, the groove 5 b is generally triangular in cross section considering the machinability of forming the groove 5 b; however, this embodiment is not limited thereto but may also employ a rectangular or semi-circular shape, for example.
[Eighth Embodiment]
In the seventh embodiment, the rod-shaped cover member 5 d was fitted into the female screw-shaped member 5 c, on the inner circumferential wall of which was formed the spiral groove 5 b, to block the opening side of the groove 5 b formed on the female screw-shaped member 5 c, thus forming a spiral liquid channel. In contrast to this, as shown in FIG. 12, this embodiment has a spiral liquid channel that is defined by a male screw-shaped member 5 e on the outer circumferential wall of which is formed a spiral groove 5 b and a cylindrical member 5 g having a hole portion 5 f into which the male screw-shaped member 5 e is fitted. In this configuration, the male screw-shaped member 5 e is securely fitted into the cylindrical member 5 g.
Like the seventh embodiment, this feature also allows this embodiment to reduce the size of the plate 5 a closing the groove 5 b formed on the male screw-shaped member 5 e while ensuring a required length of the liquid channel serving as the throttle means or of the groove 5 b, thereby preventing the counter-stream-mode oscillating-flow heat transport apparatus 1 from increasing in size. At the same time, the feature also prevents the channel connecting the heat transport device assembly 2 (the flow path 3) and the buffer tank 6 from having an excessively reduced channel resistance (flow path resistance), thereby preventing degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus 1.
On the other hand, this feature also allows for elongating the length of the liquid channel or the groove 5 b to thereby ensure a required channel resistance (flow path resistance). This allows for making the liquid channel more resistant to clogging as compared with a case where the channel resistance is provided by the liquid channel being reduced in cross section, thereby providing higher reliability for the counter-stream-mode oscillating-flow heat transport apparatus 1. In this embodiment, the communication hole formed in the heat transport device assembly 2 to communicate with the liquid tank chamber 6 a is employed as the cylindrical member 5 g; however, this embodiment is not limited thereto.
[Ninth Embodiment]
In the sixth to eighth embodiments, the spiral groove 5 b or the throttle means was provided on the heat transport device assembly 2; however, as shown in FIG. 13, in this embodiment, the spiral groove 5 b or the throttle means is provided in the oscillator 4. In FIG. 13, the groove 5 b has a spiral shape; however, this embodiment is not limited thereto but may also employ a scroll-patterned groove 5 b.
[Tenth Embodiment]
Unlike the aforementioned embodiments, this embodiment is adapted such that the buffer tank 6 is formed in a spherical and capsular shape so as to be movable through a liquid. As shown in FIGS. 14A and 14B, the buffer tank 6 includes a weight portion 6 h provided by the outer shell of the tank being increased in thickness and a throttle portion 5 that passes through the weight portion 6 h for fluid communication between the inside and outside of the buffer tank. The buffer tank 6 is filled with a liquid L and a gas G in its inner space.
Furthermore, the buffer tank 6 is located within a reserve tank 8 that communicates with the flow path 3 via a communication path 7 and is filled with the liquid L. The communication path 7 has the maximum diameter that is smaller than the minimum diameter of the buffer tank 6, thereby preventing the buffer tank 6 from flowing into the flow path 3.
According to this feature, the weight portion 6 h is naturally located in the direction of gravity (downwardly in FIG. 14), thereby allowing a tank inner opening 5 h of the throttle portion 5 to be always immersed in the liquid. Accordingly, even when the buffer tank 6 rotates by 90 degrees to change its orientation from that shown in FIG. 14A to FIG. 14B, this feature prevents a gas from going into the heat transport device assembly 2 (the flow path 3). At the same time, the feature prevents degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus while accommodating changes in volume of the liquid.
Furthermore, this embodiment allows for accommodating changes in volume of the liquid by dispensing with both the bellows 6 b defining the liquid tank chamber 6 a and the elastic member for defining the gas tank chamber 6 d and the liquid tank chamber 6 a, both of which were employed in the aforementioned embodiments. The bellows 6 band the elastic member, which are movable, may be broken or cracked due to changes over time.
However, in this embodiment, an increase in volume of the liquid would cause the gas in the buffer tank 6 to be compressed, thereby accommodating the increase in volume of the liquid. On the other hand, a decrease in volume of the liquid would cause the liquid in the buffer tank 6 to flow into the flow path 3, thereby preventing the decrease in volume of the liquid. This embodiment allows for making use of these effects without the movable and elastic portions vulnerable to changes over time, thereby providing enhanced durability.
Furthermore, this embodiment employs the spherical buffer tank 6, thereby allowing the weight portion 6 h to quickly orient in the direction of gravity when the buffer tank 6 changes its orientation. The buffer tank 6 would rotate 90 degrees to change its orientation when a device (e.g., a computer or an inverter to be cooled), into which the counter-stream-mode oscillating-flow heat transport apparatus 1 is incorporated and from which heat is to be transported, is placed from one orientation to another by a user, e.g., from vertical to horizontal orientation.
[Eleventh Embodiment]
This embodiment is configured generally in the same manner as the tenth embodiment; however, the throttle portion 5 is secured with a fixing material 9 as shown in FIG. 15. As in this embodiment, the throttle portion 5 can be secured to the buffer tank 6 with the fixing material 9, allowing the fixing material 9 to be used as a weight portion. Any material may be used as the fixing material 9 but a watertight material is preferably used including welding materials, solders, brazing materials, or adhesives.
[Twelfth Embodiment]
This embodiment is configured generally in the same manner as the eleventh embodiment; however, as shown in FIG. 16, the channel in the throttle member 5 is extended and bent as well, thereby allowing the liquid in the throttle member 5 to experience an increased channel resistance. For example, to obtain the same channel resistance as that of the throttle member 5 having a short and straight channel as in the eleventh embodiment, this feature allows the throttle member 5 to have an increased inner diameter. It is thus made possible to prevent the liquid from remaining (clogging) in the throttle member 5.
[Thirteenth Embodiment]
In this embodiment, as shown in FIG. 17, a female screw portion 6 i is formed in the outer shell of the buffer tank 6, allowing a bolt 10, having a male screw portion 10 a and a weight portion 10 b, to be screwed into the female screw portion 6 i. The bolt 10 is provided with a throttle portion 5 formed so as to pass through the weight portion 10 b (the head of the bolt 10) and the male screw portion 10 a. This makes it possible to easily integrate the throttle portion 5 and the weight portion 10 b with the buffer tank 6 by screwing the bolt 10 into the buffer tank 6.
[Fourteenth Embodiment]
This embodiment is configured generally in the same manner as the eleventh embodiment; however, the outer shell of the buffer tank 6 has a polygonal shape with straight faces (FIG. 18). This feature allows for easily manufacturing the buffer tank 6 as compared with the outer shell being spherical in shape, thereby providing the buffer tank 6 at reduced costs.
[Fifteenth Embodiment]
As shown in FIG. 19, this embodiment has a plurality of buffer tanks 6 positioned in the reserve tank 8. This configuration allows for reducing each buffer tank 6 in size as compared with one buffer tank 6 being in use. In other words, the amount of gas present in the buffer tank 6 can be reduced. For example, this feature allows for reducing the amount of gas flowing out of the buffer tank 6 when the weight portion 6 h of a buffer tank 6 is not oriented in the direction of gravity.
The tank inner opening 5 h of the throttle portion 5 may be disposed to project into the buffer tank 6 as shown in FIGS. 15 and 16. This would allow part of the gas to remain in the buffer tank 6 even when the weight portion 6 h of the buffer tank 6 is not oriented in the direction of gravity, thereby reducing the amount of gas flowing out of the buffer tank 6.
[Sixteenth Embodiment]
As shown in FIG. 20, this embodiment has a plurality of communication paths 7 disposed to communicate between the reserve tank 8 and the flow path 3. This configuration prevents the buffer tank 6 from blocking a communication path 7, and ensures that the buffer tank 6 in the reserve tank 8 accommodates an increase in volume of the liquid in the flow path 3. In this embodiment, the number of communication paths 7 is greater than that of the buffer tanks 6 so that the flow path 3 communicates with the reserve tank 8 via at least one communication path 7 even if the remaining communication paths 7 are blocked by the buffer tanks 6.
[Other Embodiments]
The aforementioned embodiments apply the counter-stream-mode oscillating-flow heat transport apparatus according to the present invention to a cooling device used for electronic components such as integrated circuits or the like in computers; however, the present invention is not limited thereto, but may be applied to other devices.
Furthermore, in the aforementioned embodiments, the bellows 6 b was used as a partitioning member for defining the gas tank chamber 6 d or the atmospheric side and the liquid tank chamber 6 a; however, the present invention is not limited thereto, but a thin film such as a diaphragm or a piston may also be used, for example.
Furthermore, in the aforementioned embodiments, the capillary tube 5 was used as the throttle means; however, the present invention is not limited thereto, but the throttle means may also include an orifice (small hole) having a hole of a predetermined diameter, for example. On the other hand, it is also acceptable to provide a plurality of throttle means as the aforementioned throttle means.
Furthermore, in the aforementioned embodiments, the degree of opening of the throttle means was set to a fixed value; however, the present invention is not limited thereto, but the degree of opening of the throttle means may also be varied according to the frequency of oscillations provided by the oscillator 4, for example. Additionally, in the aforementioned embodiments, the buffer tank 6 was placed in communication with the flow path 3 near the oscillator 4; however, the present invention is not limited thereto, but the flow path 3 and the buffer tank 6 may also be placed in communication with each other at any position.
Still furthermore, such an example has been shown in the aforementioned eleventh, and fourteenth to sixteenth embodiments in which the throttle portion 5 is straight; however, the throttle portion 5 may also be naturally implemented in the form of the capillary tube according to the second embodiment or the liquid channel according to the sixth to ninth embodiments.
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Claims

1. A counter-stream-mode oscillating-flow heat transport apparatus for inducing oscillatory movement in a liquid flowing in opposite directions through adjacent flow paths to transfer heat between the adjacent flow paths and thereby transport heat from a hot area to a cold area, the apparatus comprising:

a buffer tank that is placed in communication with the flow path for accommodating changes in volume of the liquid; and

means for throttling between the flow path and the buffer tank so that the flow path and the buffer tank can communicate with each other, wherein the throttle means has a predetermined channel resistance.

2. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 1, wherein the throttle means comprises a capillary tube having a channel of a predetermined length.

3. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 1, wherein

the throttle means comprises an orifice having a hole of a predetermined diameter.

4. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 1, the throttle means further comprising:

means for channeling liquid, the liquid channel means formed in a scroll pattern.

5. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 4, the liquid channel means further comprising:

a plate having a groove formed in a scroll pattern.

6. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 1, the throttle means further comprising:

means for channeling liquid, the liquid channel means formed in a spiral fashion.

7. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 6, the liquid channel means further comprising:

a female screw-shaped member having a spiral groove formed on an inner circumferential wall thereof and a rod-shaped cover member fitted into the female screw-shaped member.

8. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 6, the liquid channel means further comprising:

a male screw-shaped member having a spiral groove formed on an outer circumferential wall thereof and a cylindrical member having a hole portion fitted over the male screw-shaped member.

9. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 5, wherein

the groove is generally triangular in cross section.

10. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 1, further comprising:

a fluid tank chamber located in the buffer tank, the fluid tank chamber fillable with a fluid, wherein the throttle means is in communication with the tank chamber.

11. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 10, further comprising:

a gas tank chamber located in the buffer tank, the gas tank chamber fillable with a gas; and

a partition for defining the liquid tank chamber and the gas tank chamber, the partition being elastically deformable and displaceable.

12. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 11, wherein

the partition comprises a bellows.

13. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 11, wherein

the partition is formed of a bag-shaped thin-film member of an elastic material.

14. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 1, the buffer tank further comprising:

means for correcting an opening position of a buffer tank side opening of the throttle means below a liquid and gas interface.

15. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 1, wherein

the buffer tank is located in liquid and formed in a capsule shape defining an inner space therein, and

the throttle means is integrated with the buffer tank, the buffer tank having a gas and a liquid filled in the inner space thereof and including a weight portion for orienting a tank inner opening of the throttle means such that the tank inner opening is immersed in the liquid.

16. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 15, further comprising:

a female screw portion formed in the buffer tank, and a bolt-shaped member integrated with a male screw portion screwed into the female screw portion and the weight portion, wherein the throttle means passes through the male screw portion and the weight portion.

17. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 2, wherein

the buffer tank is located in the liquid and formed in a capsule shape defining a space therein, and

18. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 15, further comprising:

a reserve tank provided with a communication path in communication with the flow path and filled with the liquid therein, and wherein

the buffer tank is located inside the reserve tank.

19. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 18, further comprising:

a plurality of the buffer tanks located in the reserve tank.

20. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 18, further comprising:

a plurality of the communication paths.

21. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 15, wherein

the buffer tank is generally spherical in shape.

22. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 15, wherein

the weight portion is formed of a fixing material for securing the throttle means to the buffer tank.

23. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 1, wherein

the channel resistance across the throttle means is from 0.1% to 5% of the channel resistance across the flow path.

24. The counter-stream-mode oscillating-flow heat transport apparatus according to claim 1, wherein

the channel resistance across the throttle means is from 0.5% to 3% of the channel resistance across the flow path.