MXPA98007918A - Complete thermal dissipator - Google Patents

Abstract

The present invention relates to a heat sink with a thermal transfer medium for improving the heat transfer capacity of the heat sink. In one embodiment, the heat sink comprises a plurality of fins with cavities, a base and a fluid heat transfer medium. The fins are in thermal contact with the base and form to form a series of longitudinal channels through which air or a fluid medium can pass. The middle of each of the cavities. The fluid heat transfer medium improves the capacity of the heat sink to transfer heat without increasing surface area, size and / or weight. This improvement is due to the latent heats of evaporation and condensation of the fluid thermal transfer medium. Specifically, a greater amount of energy is required to evaporate the fluid thermal transfer medium. In this way, a large amount of heat can be conducted from the base to the fluid thermal transfer medium. On the contrary, as the evaporated fluid thermal transfer medium condenses in the upper cooler walls of the fins, a large amount of energy is conducted from the evaporated fluid heat transfer medium to the fins. Thus, a greater amount of heat can be conducted from the fluid thermal transfer medium to the fins that can then dissipate the heat to lower temperature environments.

Description

-3- 1 COMPOSITE THERMAL DISSIPATOR FIELD OF INVENTION The invention relates to transferring heat away from thermal sources and more specifically to thermal dissipators. BACKGROUND OF THE RELATED ART Heat sinks are used in designs of electronic equipment to transfer heat from a heat source, such as an electronic component, to environments of lower temperature. The objective of a heat sink is to reduce the temperature of a heat generator to avoid degradation in performance and prolong the duration of the thermal source. A typical heat sink comprises a bottom plate and a plurality of fins.

The plurality of fins are connected vertically to the bottom plate and are configured to constitute a series of longitudinal channels. To transfer heat from a thermal source, the bottom plate of the heat sink is fixed to the heat source such that the thermal contact is achieve with the thermal source. Heat is conducted from the thermal source to the bottom plate which is then led to the fins where it is dissipated by thermal transfer to the lower temperature environments, such as air passing through the longitudinal channels. The speed of typical thermal transfer of a heatsink is REF. 28216 in the range of 50 to 200 watts per .0929 m2 (square foot) and depends on the available extended surface area, ambient operating temperatures, and material / material thickness. The effectiveness of a heat sink depends on its ability to transfer heat from the thermal source to lower temperature environments. Some sectors that influence this capacity include the thermal transfer rate of the material from which the heatsink is built and the surface area of the heatsink. The heat transfer capacity of a heat sink can be increased by using a material with a higher thermal transfer rate to build the heat sink. Heat sinks typically comprise a solid piece of material having high conductivity with adequate mechanical strength for secondary support functions. Materials that possess these qualities include metals or metallized plastics, such as aluminum and copper. The thermal transfer rates for the aforementioned metals and metallized plastics are as follows: 0.19 ° Celsius / Watt-2.54 cm (inch) and 0.1 ° Celsius / att-2.54 cm (inch), respectively. The heat transfer capacity of a heat sink can also be increased by increasing the surface area through which the heat can be dissipated, for example to lengthen the fins. However, this results in increases in the size and weight of the heatsink. These increases are undesirable especially when space is limited. COMPENDIUM OF THE INVENTION The present invention is a heat sink with a thermal transfer medium for improving the heat transfer capacity of the heat sink without increasing its size and / or weight. In one embodiment, the heat sink comprises a plurality of fins with cavities, a base and a fluid heat transfer medium. Each of the fins is in terminal contact with the base and configured to form a series of longitudinal channels through which air or a fluid medium can pass. The fins and base are constructed from thermally conductive material with adequate mechanical strength for secondary support functions. The fluid thermal transfer medium is contained within each of the cavities. The fluid thermal transfer medium can be a fluid, thermal resistance and a boiling point lower than the thermal resistance and softening point, respectively of the material used to build the fins and bases. This fluid transfer medium improves the capacity of the heat sink to transfer heat due to its latent heats of evaporation and condensation. Specifically, a large amount of energy is required to evaporate the fluid thermal transfer medium. In this way, a large amount of heat can be conducted from the base to the fluid thermal transfer medium. On the contrary, as the evaporated fluid thermal transfer medium condenses in the upper cooler walls of the fins, a large amount of energy is conducted from the vaporized fluid heat transfer medium to the fins. In this way, a large amount of heat can be conducted from the fluid heat transfer medium to the fins which can then dissipate the heat to lower temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS The features, aspects and advantages of the present invention will be better understood with respect to the following description, the accompanying claims and drawings in which: Figure 1 illustrates a heat sink according to the present invention, - The Figure 2 illustrates a heat sink with a base that has a reservoir a fluid heat transfer medium is contained; Figure 3 illustrates a heat sink with fins having a rectangular shape; Figure 4 illustrates a non-level application of a heat sink with a base having a reservoir; Figure 5 illustrates a heatsink with a base having a reservoir wherein a fluid heat transfer medium and a wick are contained; Figure 6 illustrates the heat sink of the Figure 1 wherein a porous metal wick 50 is contained within the fin cavities; and Figure 7 illustrates the heat sink of the Figure 2 wherein a porous metal wick is contained within the heat sink cavities. DETAILED DESCRIPTION Figure 1 illustrates a heat sink 10 according to the present invention. The heat sink 10 comprises a base 12, a plurality of fins 14 and a heat transfer medium 16. The base 12 can be of any suitable dimensions or shape depending on the use for which it is intended, such as a flat rectangular plate. In general, the dimensions and shape of the base 12 should allow good thermal contact between the thermal source and the heat sink. For example, if the thermal source has a rectangular shape and a flat upper surface, the base should have a rectangular shape and a flat bottom surface in order to achieve good thermal contact with the upper part of the thermal source. The base 12 is constructed from a thermally conductive material such as aluminum, aluminum alloys, copper, copper alloys and thin-walled polymers or conductors. The fins 14 are in thermal contact with the base 12 and are placed vertically in their base 13 to the upper surface of the base 12 to increase the surface area of the heat sink 10. The fins 14 are configured to form longitudinal channels through which can pass air or a fluid medium and disparate heat. The fins 14 can be of any convenient dimensions and shape. In general, the fins 14 have a tabular, cylindrical or rectangular shape, wherein the width of the fins 14 is gradually reduced from the base 13 to the tip 15 of the fins 1. The fins 12 are constructed from a thermally conductive material, such as aluminum, aluminum alloys, copper and copper alloys. Each of the fins 14 has a fin cavity 18 in which the thermal transfer medium 16 is contained. The fin cavities 18 can be completely circumscribed within the walls of the fins 14 as illustrated in Figure 1, or circumscribed < 9 7 using the base 12. The thermal transfer medium can be a fluid thermal transfer medium or a conductive thermal transfer medium depending on the requirements of the application. Fluid thermal transfer means 5 include any fluids which tends to a thermal resistance at a boiling point lower than the thermal resistance and softening point respectively of the material used to build the fins and the base. Additionally, the means of fluid thermal transfer shall not cause the fins and / or bases to be subjected to corrosion. The fluid thermal transfer medium includes fluids such as tap water, distilled water, alcohol or a combination of those mentioned above. The means of fluid thermal transfer 16 should only partially fill the fin cavities 18 to allow evaporation and condensation. The fluid heat transfer medium improves the capacity of the heat sink to transfer heat without increasing its surface area, size or weight. This improvement is due to the latent heats of evaporation and condensation of the fluid thermal transfer medium. Specifically, high energy levels are required to evaporate the fluid thermal transfer medium. This Thus, a large amount of heat can be conducted from the base (or base of the fins) to the fluid thermal transfer medium. Conversely as the evaporated fluid transfer medium condenses in the upper cooler walls of the fins, high levels of energy are conducted from the evaporated fluid transfer medium to the fins. In this way, a large amount of heat can be conducted from the fluid heat transfer medium to the fins. The fin cavities 18 are evacuated from air and seal to prevent air or fluids from entering or leaving the fin cavities 18. Each of the fins 18 may include a hole through which air is evacuated from the fin cavities. 18 and the fluid heat transfer medium 112 is introduced into the fin cavities 18. The holes are sealed using plugs 19. The seal plugs 19 can be constructed using a thermally conductive material such as brass, tin solder, solder high temperature, polymer resin, a threaded metal valve / plug system. The second type of thermal transfer means are conductive transfer means, which include any conductive thermal material (solid or liquid) with less thermal resistance than the material used to construct the fins and / or base. These heat transfer media should also be lightweight (compared to fins and / or base) and inexpensive. Examples of conductive heat transfer media include conductive polymers, solid metals, tin, tin alloys, tin solders, metal-filled polymers and conductive liquid polymers. The conductive thermal transfer media must completely fill the cavity to achieve good thermal contact between the fins and the base. The dimensions of the heat sink 10 should vary within each thermal application. The following example is given for illustrative purposes and should not be construed as limiting the present invention in any way. In this example, the base 12 is rectangular in shape with a thickness of 75 to 125 mm, a length of 304 mm and a width of 304 mm. The fins 14 are tabular with a height of 500 mm, a base diameter of 20 to 40 mm and a tip diameter of 10 to 20 mm. The thickness of the fin walls is approximately 10 mm. If the conductive thermal transfer medium is distilled water, the thermal transfer rate of the heat sink should be approximately 800 to 1,000 watts per .0929 m2 (square foot) . This is significantly greater than the thermal transfer rate of typical prior art heat sinks.

Figure 2 shows a heatsink 20 with a base 22 having a reservoir 24 where the fluid heat transfer medium 26 is contained according to an embodiment of the present invention. Each of the fins 25 has a fin cavity 27 which, in conjunction with the reservoir 24 and other fin cavities 27, form a heat sink cavity 28. Alternatively, the base 22 can have multiple reservoirs to form multiple cavities thermal dissipators with fin cavities. The heat sink 20 includes a single hole through which air is evacuated from the heat sink cavity 28 and the fluid heat transfer medium 26 is inserted into the cavity of the heat sink 28. The hole is sealed using a plug 30. The fins 26 of Figure 2 have a tubular shape. Figure 3 illustrates the heat sink 20 with fins 25 having a rectangular shape. In level applications (or positions) the fluid thermal transfer medium should be evenly distributed through the reservoir 24. Applications that are not at the level of the heatsink 20 of Figures 2 and 3, will cause a non-uniform distribution of the transfer medium thermal fluid in the reservoir 24. Specifically, the fluid thermal transfer medium will be collected to the lower side of the reservoir 24. FIG. 4 illustrates a non-level application of the heatsink 20. A uniform distribution of the fluid thermal transfer medium in the reservoir 24 allows greater thermal contact between the fluid heat transfer medium and the base. The non-uniform distribution of the fluid heat transfer medium adversely affects the thermal contact with the base, which in turn compromises the heat transfer capacity of the heat sink. Figure 5 illustrates a heat sink 40, a base 42 having a reservoir 44 in which a fluid heat transfer medium 46 and a wick 48 are contained according to one embodiment of the present invention. The wick 48 provides a more even distribution of the fluid heat transfer medium through the reservoir 44, particularly in applications not at the level of the heatsink 40. The wick 40 should be porous for capillary transport of the fluid transfer means 46 and can be constructed from metals, such as copper, aluminum, plastics, glass or ceramics. Figure 6 illustrates the heat sink 10 of the Figure 1, wherein a porous metal wick 50 is contained within the fin cavities 18 and Figure 7 illustrates the heatsink 20 of Figure 2 wherein a porous metal wick 60 is contained within the heatsink cavity. 28 according to another embodiment of the present invention. In these embodiments the porous metal wicks 50, 60 provide a more even distribution of fluid heat transfer media through the fin and / or deposit cavities, regardless of the orientation of the heat sinks 20, 30 thereby allowing the transfer operation in any orientation. Although the present invention has been described in considerable detail with reference to certain embodiments, other versions are possible. Therefore, the spirit and scope of the present invention will not be limited in the description of the modalities contained herein. It is stated that in relation to this date, the best method known by. The applicant for carrying out said invention is the conventional one for the manufacture of the objects to which it refers. Having described the invention as above, the content of the following is claimed as property:

Claims (20)

1. CLAIMS 1.- A heat sink, characterized in that it comprises: a base; a plurality of fins having cavities; and a thermal transfer medium contained within the cavities and in thermal contact with the base.
2. 2. - The heat sink according to claim 1, characterized in that the heat transfer medium is a conductive thermal transfer medium.
3. 3. - The heat sink according to claim 1, characterized in that the heat transfer medium is a fluid having thermal resistance and boiling point lower than the thermal resistance and softening points of the base and the plurality of fins.
4. 4. - The heat sink according to claim 3, characterized in that a porous wick contained within the cavities.
5. 5. The heat sink according to claim 1, characterized in that the thermal transfer means comprises water.
6. 6. - The heat sink according to claim 1, characterized in that the thermal transfer means comprises alcohol.
7. 7. - The heat sink according to claim 1, characterized in that the thermal transfer means comprises a conductive thermal material having a thermal resistance lower than the thermal resistance of the base and the plurality of fins.
8. 8. The heat sink according to claim 1, characterized in that the plurality of fins is configured to form longitudinal channels.
9. 9. - The heat sink according to claim 1, characterized in that each of the plurality of fins are constructed of a conductive thermal material.
10. 10. - The heat sink according to claim 1, characterized in that the base is constructed of a conductive thermal material.
11. 11. A thermal dissipator characterized in that it comprises: a base having a 'reservoir; a plurality of fins having fin cavities and positioned such that the fin cavities form one or more heat sink cavities with the reservoir; and a thermal transfer medium contained within the heat sink cavities.
12. 12. - The heat sink according to claim 11, characterized in that the liquid transfer medium is a conductive thermal transfer medium.
13. 13. The heat sink according to claim 11, characterized in that the heat transfer medium is a fluid that has thermal resistance and a lower boiling point than the thermal resistances and softening points of the base and the plurality of fins.
14. 14. - The heat sink according to claim 13, characterized in that a porous wick contained within the tank.
15. 15. - The heat sink according to claim 13, characterized in that a porous wick contained within the fin cavities.
16. 16. The heat sink according to claim 11, characterized in that the thermal transfer means comprises water.
17. 17. The heat sink according to claim 11, characterized in that the thermal transfer medium comprises alcohol.
18. 18. - The heat sink according to claim 11, characterized in that the thermal transfer medium comprises a conductive thermal material that has lower thermal resistance than the thermal resistance of the base and the plurality of fins.
19. 19. - The heat sink according to claim 11, characterized in that the plurality of fins is configured to form longitudinal channels.
20. 20. The heat sink according to claim 11, characterized in that the plurality of fins and the base are constructed of a conductive thermal material. SUMMARY OF THE INVENTION The present invention relates to a heat sink with a thermal transfer medium for improving the heat transfer capacity of the heat sink. In a modality, the heat sink comprises a plurality of fins with cavities, a base and a fluid thermal transfer medium. The fins are in thermal contact with the base and form to form a series of longitudinal channels through which air or a fluid medium can pass. The fluid thermal transfer medium is contained within each of the cavities. The fluid heat transfer medium improves the capacity of the heat sink to transfer heat without increasing its surface area, size and / or weight. This improvement is due to the latent heats of evaporation and condensation of the fluid thermal transfer medium. Specifically, a greater amount of energy is required to evaporate the fluid thermal transfer medium. In this way, a large amount of heat can be conducted from the base to the fluid thermal transfer medium. On the contrary, as the evaporated fluid thermal transfer medium condenses in the upper cooler walls of the fins, a large amount of energy is conducted from the evaporated fluid heat transfer medium to the fins. Thus, a greater amount of heat can be conducted from the fluid thermal transfer medium to the fins which can then dissipate the heat to lower temperature environments.