EP3006885B1

EP3006885B1 - Hybrid heat pipe assembly with bonded fins on the baseplate

Info

Publication number: EP3006885B1
Application number: EP15188786.6A
Authority: EP
Inventors: Ahmed Zaghlol
Original assignee: Mersen Canada Toronto Inc
Current assignee: Mersen Canada Toronto Inc
Priority date: 2014-10-08
Filing date: 2015-10-07
Publication date: 2020-06-17
Anticipated expiration: 2035-10-07
Also published as: CA2907056A1; EP3006885A1; CA2907056C; US20160102920A1

Description

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/061,311, filed October 8, 2014 .

FIELD OF THE INVENTION

The following disclosure is directed generally to hybrid heat pipe assemblies.

BACKGROUND OF THE INVENTION

US 2005/094375 A1 discloses an integrated heat dissipating device has a heat sink, a first set of fins, a second set of fins and at least one heat pipe. The heat sink has a thermal conductive block embedded therein and a through hole exposing the thermal conductive block from a top surface of the heat sink. The first set of fins has a plurality of horizontally extending fins stacked with each other along a vertical direction over the heat sink. The second set of fins is integrated by a plurality of vertically extending fins arranged in a curved shape between the heat sink and the first set of fins. The heat pipe has a vertical extension across the first set of fins and a horizontal extension underneath a bottom of the first set of fins. The horizontal extension is inserted into the through hole in contact with the thermal conductive block.
EP 1 387 139 A1 discloses a heat pipe unit comprised of a tank a plurality of pipes provided upright and jointed to a side of the tank to be in communication with the tank, and a plurality of fins fitted over and assembled to the plurality of pipes.
US 6,779,595 B1 discloses a first heat dissipating element mounted to the thermal conductive surface of the thermal conductive heat sink and a heat pipe and a second heat dissipating element comprising a plurality of fins with holes through which a heat pipe is mounted.
A device usually generates heat as a result of losses in efficiency. A heat sink is a passive heat exchanger that can cool a device by transferring heat generated by the device into a surrounding cooling medium, such as air. A heat sink may have a baseplate that can extract heat from a device that is in contact with the baseplate. A heat sink may also include an assembly of fins bonded to the baseplate that can transfer the extracted heat from the baseplate to the surrounding cooling medium. Thus, there is a flow of heat from the device through the baseplate and the fins to the surrounding cooling medium, thereby serving to cool the device in contact with the baseplate.
Since the heat sink is a passive heat transfer mechanism, there may be situations in which the heat sink is not able to adequately cool a device in contact therewith. In such cases, a heat pipe apparatus might be applied. A heat pipe apparatus is also a heat exchanger than can cool a device by transferring heat generated by the device into a surrounding cooling medium. The heat pipe apparatus may include an evaporator plate that can extract heat from a device that is in contact with the evaporator plate. The apparatus may also include a plurality of heat pipes in contact with the evaporator plate that can transfer heat from the evaporator plate to another location using liquid-to-vapor phase changes.
Each of the heat pipes includes a working fluid, such as water, sealed in a long thin walled cavity under vacuum. The cavity may be cylindrical or rectangular, but is not limited thereto. When heat is applied to a portion of the heat pipe, the working fluid boils and is converted into vapor. The vapor moves from the heated portion, or an evaporating area, of the pipe to a lower temperature area, or a condensing area, of the heat pipe via an adiabatic portion of the pipe where no phase change takes place. The lower temperature area of the heat pipe is at an opposite end of the heat pipe from the end of the heat pipe in contact with the evaporator plate. In the lower temperature area of the heat pipe, the vapor will condense back into a liquid. The liquid will move back to the heated area of the heat pipe via the adiabatic portion of the pipe to be heated and evaporated again. Thus, a two-phase flow cycle is created.
The condensed liquid moves from the lower temperature area of the heat pipe to the heated area of the heat pipe using gravity or a wicking structure. If the liquid moves back to the heated area as a result of gravity, the heat pipe has been oriented in such a way that gravity can draw the condensed liquid down toward the heated portion of the heat pipe. For example, such an orientation may include a heat pipe being angled downwardly from the lower temperature area of the heat pipe to the heated area of the heated pipe. This allows gravity to draw the condensed liquid from the higher, condensing area of the heat pipe toward the lower, evaporating area of the heat pipe.
A large fin stack is positioned around the lower temperature area, and possibly the adiabatic portion, of the heat pipe. The fin stack can transfer the heat away from the heat pipes into the air through forced or natural convection.
However, even such a heat pipe apparatus may not be effective to dissipate heat from certain devices that are either exceedingly inefficient or of a size significant enough to require a greater cooling capacity than such a heat pipe apparatus can provide on its own.

SUMMARY OF THE INVENTION

Described herein are multiple example embodiments related to hybrid heat pipe assemblies.
According to the invention, a hybrid heat pipe assembly is provided according to claim 1.
The complex heat pipe extends from the baseplate and through the fins and the heat pipe fin stack. In an embodiment, the fins are bonded to the baseplate in a plurality of groups. The groups are separated from each other by the complex heat pipe. In a further embodiment, the complex heat pipe extends from the baseplate and through two of the fin groups and the heat pipe fin stack. Each of the complex heat pipes extends through the heat pipe fin stack.
The heat pipe fin stack includes a heat pipe protective fin into which the complex heat pipe extends. The heat pipe protective fin is positioned on an opposite side of the heat pipe fin stack from the fins. The heat pipe protective fin is positioned adjacent to one end of the complex heat pipe. Another end of the complex heat pipe is embedded in the baseplate.
In an embodiment, the fins bonded to the baseplate are mounted to an opposite side of the baseplate from a side of the baseplate in contact with the device. In still another embodiment, the complex heat pipe is embedded in the baseplate.
The complex heat pipes extend from the chamber through the fins and the heat pipe fin stack. In an embodiment, the fins are bonded to the baseplate in a plurality of groups, and the groups are separated from each other by the complex heat pipes. In an embodiment, the complex heat pipes extend from the chamber through two of the fin groups and the heat pipe fin stack. In an example, the chamber is mounted horizontally in the baseplate. The chamber is embedded in the baseplate. The chamber is positioned in a baseplate channel comprising walls defining the baseplate channel, the chamber being secured to the walls.
Other features and aspects may be apparent from the following detailed description, the drawings and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an example of a hybrid heat pipe assembly.
FIG. 2 is front view illustrating an example of the hybrid heat pipe assembly shown in FIG. 1.
FIG. 3 is a side cross-sectional view taken along lines 3-3 of FIG. 2 illustrating an example of the hybrid heat pipe assembly shown in FIG. 1.
FIG. 4 is a close-up view of area 4 of FIG. 3 illustrating an example of an interface of a baseplate and a complex heat pipe of the hybrid heat pipe assembly shown in FIG. 1.
FIG. 5 is a perspective view illustrating an example of a complex heat pipe of the hybrid heat pipe assembly shown in FIG. 1.
FIG. 6 is a perspective view illustrating an example of the hybrid heat pipe assembly shown in FIG. 1 with devices in contact therewith.

Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration and convenience.

DETAILED DESCRIPTION

Examples incorporating one or more embodiments are described and illustrated in the drawings. These illustrated examples are not intended to be limiting. For example, one or more aspects of an embodiment may be utilized in other embodiments and even other types of devices.
FIGS. 1-6 illustrate an example hybrid heat pipe assembly in surface contact with a plurality of devices 4. While the devices 4 illustrated in FIG. 6 bear a common resemblance with electronic modules, embodiments described herein are not limited thereto. In fact, one having ordinary skill in the art may use the hybrid heat pipe assembly 2 to cool any applicable heat-generating device having the ability to be in contact with the hybrid heat pipe assembly 2.
While the devices 4 illustrated in FIG. 6 are mounted to the hybrid heat pipe assembly 2 using fasteners 6, embodiments described herein are not limited thereto. For example, the devices 4 may merely be in contact with the hybrid heat pipe assembly 2 without being fixed or mounted thereto. In addition, the devices 4 contacting the hybrid heat pipe assembly 2 may be related or unrelated to each other. Moreover, the devices 4 may be in contact with or isolated from each other. Whatever the case, the devices 4 to be cooled by the hybrid heat pipe assembly 2 are positioned with respect to the hybrid heat pipe assembly in such a way as to maximize surface contact with the hybrid heat pipe assembly 2, thereby serving to increase an amount of heat extracted from the devices 4 by the hybrid heat pipe assembly 2.
The illustrated hybrid heat pipe assembly 2 may combine various aspects and elements of a bonded fin heat sink and a heat pipe apparatus. However, the hybrid heat pipe assembly 2 is not limited thereto and can be further supplemented by other heat transfer means known by those of ordinary skill in the art.
The example hybrid heat pipe assembly 2 described and illustrated herein includes a baseplate 8 in contact with the devices 4, baseplate fins 10 bonded to the baseplate 8, a complex heat pipe 12 extending from the baseplate 8 and having an end positioned within the baseplate 8, and a heat pipe fin stack 14 joined to the complex heat pipe 12.
The baseplate 8 is configured to extract heat from the devices 4 in contact with the baseplate 8. As was previously noted with respect to the hybrid heat pipe assembly 2, while the devices 4 illustrated in FIG. 6 are mounted to the baseplate 8 using fasteners 6, embodiments described herein are not limited thereto. For example, the devices 4 may be in contact with the baseplate 8 without being fixed or mounted thereto. In addition, the devices 4 may be related or unrelated to each other or other items contacting the baseplate 8.
The baseplate 8 may have a shape consistent with that of a rectangular block. However, embodiments disclosed herein are not limited thereto as the baseplate 8 can have any shape or structure that is effective in cooling devices in contact therewith. Further, while the baseplate 8 is illustrated in the example herein as being flat or planar, embodiments described here are not limited thereto, as the baseplate 8 may be curved or otherwise to maximize surface contact with the devices 4 and extract heat from the devices 4 as efficiently as possible. Thus, the shape and design of the baseplate 8 may be adjusted for effective extraction of heat from whatever device might be in surface contact therewith.
The baseplate 8 may be mounted on a corresponding structure such that an edge line 20 of the baseplate 8 is parallel with gravity. However, embodiments disclosed herein are not limited thereto, as the baseplate 8 can be mounted in any plane particularly suited for cooling the devices 4 in contact therewith, as long as requirements for cooling the heat-generating devices 4 are met and acceptable support is provided for the baseplate 8.
The heat extracted from the devices 4 by the baseplate 8 may be transferred therefrom to the baseplate fins 10 bonded to the baseplate 8. The heat received by the baseplate fins 10 may be directly transferred to the air surrounding the baseplate fins 10.
The baseplate fins 10 may be mounted directly on the baseplate 8 or on a fin plate 30 that is subsequently mounted on the baseplate 8. If mounted directly on the baseplate 8, each of the baseplate fins 10 may include a flange (not shown) via which the baseplate fin 10 is fastened to the baseplate 8. The flange may extend from an edge of a body 32 of the baseplate fin 10 in a substantially perpendicular manner that is additionally substantially parallel with the sides 16, 18 of the baseplate 8. The baseplate fins 10 may be bonded to the baseplate 8 in a plurality of groups. In addition, the baseplate fins 10 may be mounted to an opposite side 16 of the baseplate 8 from a side 18 of the baseplate 8 in contact with the devices 4.
In some cases, when cooling requirements for the devices 4 are great, the heat generated by the devices 4 may be too substantial to be effectively dissipated solely by the baseplate fins 10. When this occurs, the excess heat may be dissipated from the baseplate 8 through the complex heat pipe 12. The complex heat pipe 12 may transfer the received excess heat from the baseplate 8 to the heat pipe fin stack 14 for subsequent dissipation to air surrounding the heat pipe fin stack 14.
As is the case with the baseplate fins 10, the complex heat pipe 12 is positioned on the opposite side 16 of the baseplate 8 from the side 18 of the baseplate 8 in contact with the devices 4.
The complex heat pipe 12 may be similar in design to a clarinet heat pipe or a tube that has been fabricated to seal a working fluid under vacuum pressure. Several complex heat pipes 12 may be mounted in the baseplate 8 to extend therefrom. Ends of the complex heat pipes 12 may also be embedded in the baseplate 8.
As such, a complex heat pipe 12 may separate one group of the baseplate fins 10 from another group of the baseplate fins 10. The complex heat pipe 12 may extend from the baseplate 8 and through the baseplate fins 10 and the heat pipe fin stack 14. The baseplate fins 10 may be mounted to and arranged on the baseplate 8 in a plurality of separated groups. In such cases, the groups of the baseplate fins 10 may be separated from each other by a complex heat pipe 12 extending from the baseplate 8, between the groups of the baseplate fins 10, and through the heat pipe fin stack 14. For example, two groups of baseplate fins 10 may be separated by a complex heat pipe 12 mounted to the baseplate 8 in an area between the two groups of the baseplate fins 10. The complex heat pipe 12 may extend between and past the baseplate fins 10 and into the heat pipe fin stack 14. The heat pipe fin stack 14 may be separated from the baseplate 8 by the baseplate fins 10.
Further, a complex heat pipe apparatus 22 includes a plurality of the complex heat pipes 12 secured within a closed chamber 24 that is positioned within the baseplate 8. The complex heat pipes 12 are secured within respective recesses in the closed chamber 24 by brazing the heat pipes 12 to respective walls that define the recesses. The chamber 24 is embedded in a baseplate channel 26 formed within the baseplate 8 such that chamber 24 can fit therein. The chamber 24 is welded to walls that define the baseplate channel 26. The closed chamber 24 is configured to act as a fluid reservoir within the baseplate 8 to expedite the transfer of heat from the baseplate 8 using a two-phase flow cycle created within the complex heat pipes 12.
Moreover, the closed chamber 24 may be mounted at a location in the baseplate 8 that enhances or maximizes heat extraction from the devices 4. The baseplate channel 26 location on the side 16 is essentially opposite a location on the side 18 at which the devices 4 are in surface contact therewith.
Further, the chamber 24 and the channel 26 may be correspondingly oriented to maximize exposure to devices 4 in surface contact with the baseplate 8 in order to enhance or maximize extraction of heat therefrom. For example, while both the chamber 24 and the channel 26 are illustrated herein as being straight, embodiments disclosed herein are not limited thereto, as the channel 24 can be correspondingly curved to a curved channel 26 and of the baseplate 8 in order to maximize heat extraction from a correspondingly positioned and/or shaped group of devices 4 making surface contact with the baseplate 8.
The heat pipe fin stack 14 includes a heat pipe protective fin 28 to provide protection for a complex heat pipe 12 extending therethrough. The heat pipe protective fin 28 is positioned on an opposite side of the heat pipe fin stack 14 from the baseplate fins 10 and adjacent to one end 36 of the complex heat pipe 12. The pipe end 36 may extend through the heat pipe protective fin 28, such that the pipe end 36 is separated from a remainder of the complex heat pipe 12 by the heat pipe protective fin 28. Further, an end cap 34 is positioned on the pipe end 36 of the complex heat pipe 12 to provide additional protection to the complex heat pipe 12.
In the examples described herein, the complex heat pipe 12 is positioned to absorb excess heat from the baseplate 8 when cooling requirements are high enough that the baseplate fins 10 are unable to effectively cool the devices 4 contacting the baseplate 8. As a result, melting of a devices 4 due to insufficient cooling may be inhibited.
A number of examples have been described above. Nevertheless, it will be understood that various modifications may be made. For example, suitable results may be achieved if the described elements are combined in a different manner and/or replaced or supplemented by other elements or their equivalents. Accordingly, other implementations are within the scope of the following claims.

Claims

A hybrid heat pipe assembly comprising:
a baseplate (8) dimensioned to be placed in surface contact with a device, the baseplate being configured to extract heat from the device, the baseplate having a channel (26) formed within the baseplate (8) at a location on one side (16) of the base plate (8) that is essentially opposite a location on another side (18) of the baseplate at which the device (4) is in surface contact with the baseplate (8);

a plurality of fins (10) bonded to the baseplate in parallel, the fins bonded to the baseplate being configured to transfer a first portion of the extracted heat from the baseplate (8) to air surrounding the fins bonded to the baseplate;

a complex heat pipe apparatus (22) comprising a closed chamber (24) positioned within the baseplate (8), embedded within the channel (26), and welded to walls that define the channel (26), the apparatus further comprising a plurality of complex heat pipes (12), the complex heat pipes (12) being secured within respective recesses of said closed chamber (24) by brazing the complex heat pipes (12) to respective walls that define the recesses, the complex heat pipes (12) extending from the baseplate (8) through the fins bonded to the baseplate, the closed chamber (24) being configured to act within the baseplate as a reservoir for the fluid to expedite the transfer of a second portion of the extracted heat from the baseplate (8) using a two-phase flow cycle created within the complex heat pipes (12), the closed chamber (24) being configured to transfer the second heat portion from the chamber to the complex heat pipes, the complex heat pipes being configured to receive the second heat portion; and

a heat pipe fin stack (14) through which the complex heat pipes (12) extend and to which the complex heat pipes are configured to transfer the second portion of heat, the heat pipe fin stack (14) being joined to the complex heat pipes and configured to transfer the second portion of the extracted heat received from the complex heat pipes to air surrounding the stack,

wherein the heat pipe fin stack comprises a heat pipe protective fin (28) into which the complex heat pipe extends,

wherein the heat pipe protective fin is positioned on an opposite side of the heat pipe fin stack from the fins bonded to the baseplate,

wherein the heat pipe protective fin (28) is positioned adjacent to one end of each of the complex heat pipes (12),

wherein an end cap (34) is positioned on the one end (36) of the complex heat pipes (12), wherein each of the complex heat pipes (12) extends from the baseplate to an end of each of the complex heat pipes at an oblique angle, and

wherein fins of the heat pipe fin stack (14) extend in parallel to a side (16) of the baseplate in which the channel (26) is formed.
The assembly of any one of the previous claims, wherein the heat pipe fin stack is separated from the baseplate by the fins bonded to the baseplate.
The assembly of any one of the previous claims, wherein the fins bonded to the baseplate are bonded to the baseplate in a plurality of groups, and
wherein each of the complex heat pipes separates one of the fin groups from another one of the fin groups.
The assembly of claim 3, wherein the complex heat pipes extend through two of the fin groups and the heat pipe fin stack.
The assembly of any one of the previous claims, wherein the fins (10) bonded to the baseplate are mounted to an opposite side of the plate from a side of the baseplate (8) in contact with the device.
The assembly of any one of the previous claims, wherein the complex heat pipes (12) are embedded in the baseplate.