US20050045310A1 - Heat pipe, cooling unit having the heat pipe, and electronic apparatus having the cooling unit - Google Patents

Abstract

According to one embodiment of the invention, a heat pipe features a pipe-shaped container in which an operating fluid is sealed, and a wick provided inside the container. The container has a flat heat-receiving end portion, a heat-radiating end portion being flattened in a direction different from that of the heat-receiving end portion, and a middle portion connecting the heat-receiving end portion and the heat-radiating end portion. The middle portion has a circular cross section.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2003-307423, filed Aug. 29, 2003, the entire contents of which are incorporated herein by reference.
BACKGROUND
• 1. Field
• This invention relates to a heat pipe used for conveying heat of electronic components to a heat sink, and a cooling unit using the heat pipe. Further, this invention relates to an electronic apparatus, such as a portable computer, containing heat-generating electronic components inside its housing. In particular, this invention relates to a structure of conveying heat of electronic components to a heat-radiating portion via the heat pipe.
• 2. Description of the Related Art
• The amount of heat generated by CPUs used in notebook portable computers has increased in response to an increase in their processing speed and functions. As a result, CPUs are now more susceptible in exceeding their thermal threshold, which causes a decrease in operation efficiency or causes inoperability.
• Therefore, conventional art provides various heat radiating measures to discharge heat of CPUs to the outside. Heat pipes and heat sinks are known as typical means for cooling CPUs. Jpn. Pat. Appln. KOKAI Pub. No. 2001-251079 discloses an example of a cooling unit having a heat pipe. The heat pipe used in the cooling unit has a pipe-shaped metal container. A wick is housed inside the container, which is sealed to further house operating fluid such as water. The container has a heat receiving end portion and a heat radiating end portion located opposite to the heat receiving end portion. The heat receiving end portion is thermally connected to the CPU with a heat receiving plate interposed therebetween. The heat radiating end portion is thermally connected to a heat sink.
• According to the conventional structure, the heat receiving end portion of the container receives heat of the CPU. Thereby, the operating fluid in the heat receiving end portion is heated and vaporized. This vapor flows from the heat receiving end portion to the heat radiating end portion through a vapor channel inside the container. The vapor guided into the heat-radiating end portion condensed therein. Heat radiated by the condensation is diffused by heat conduction from the heat radiating end portion to the heat sink, and radiated from the surface of the heat sink.
• The operating fluid liquefied in the heat radiating end portion is conveyed through the wick by capillary action and returns to the heat receiving end portion. The operating fluid returned to the heat receiving end portion receives heat of the CPU again. Heat of the CPU is transferred to the heat sink by the repeated evaporation and condensation of the operating fluid.
• In the above conventional cooling unit, the container is flattened through the whole length, to reduce the setting space of the heat pipe. Further, heat is transferred by a heat pipe bent by about ninety degrees (90°) in the horizontal direction, the flattened container is twisted in the third dimension between the heat receiving end portion and the heat radiating end portion, and folded by 180°.
• However, if the flattened container is twisted and folded, the heat receiving end portion and the heat radiating end portion are located on almost the same plane. As a result, the heat receiving end portion and the heat radiating end portion are flat in the same direction. Therefore, when a heat sink is thermally connected to the heat radiating end portion of the container, the shape and the orientation of the heat sink may be restricted.
• In addition, when the flattened container is twisted and folded, it is inevitable that the wick located inside the container is deformed or crushed as well. This interferes with return of the operating fluid liquefied in the heat radiating end portion to the heat receiving end portion, and thus is an obstacle to efficient heat convey.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
• The accompanying drawings, which are incorporated and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.
• FIG. 1 is a perspective view of an exemplary portable computer according to a first embodiment of the invention.
• FIG. 2 is a perspective view of the portable computer of the first embodiment of the invention, illustrating a state where a cooling unit is contained in a housing thereof.
• FIG. 3 is a perspective view of an exemplary cooling unit according to the first embodiment of the present invention.
• FIG. 4 is a cross-sectional view of an exemplary heat pipe according to the first embodiment of the present invention, illustrating a cross section of a heat-receiving end portion of a container.
• FIG. 5 is a cross-sectional view of the exemplary heat pipe according to the first embodiment of the present invention, illustrating a cross section of a heat-radiating end portion of the container.
• FIG. 6 is a cross-sectional view of the heat pipe according to the first embodiment of the present invention, illustrating a cross section of a middle portion of the container.
• FIG. 7 is a perspective view of a cooling unit according to a second embodiment of the invention.
• FIG. 8 is a perspective view of a cooling unit according to a third embodiment of the invention.
• FIG. 9 is a perspective view of a cooling unit according to a fourth embodiment of the invention.
• FIG. 10 is a perspective view of a cooling unit according to a fifth embodiment of the invention.
• FIG. 11 is a perspective view of a cooling unit according to a sixth embodiment of the invention.
• FIG. 12 is a perspective view of a portable computer according to a seventh embodiment of the present invention, illustrating a state where a cooling unit is contained in a housing thereof.
• FIG. 13A is a plan view of a heat pipe according to the seventh embodiment of the invention.
• FIG. 13B is a side view of the heat pipe according to the seventh embodiment of the present invention.
• FIG. 14A is a plan view of a heat pipe according to an eighth embodiment of the invention.
• FIG. 14B is a side view of the heat pipe according to the eighth embodiment of the invention.
DETAILED DESCRIPTION
• A first embodiment of the present invention will now be described based on FIGS.1 to6.
• FIG. 1 illustrates aportable computer1 being an example of an electronic apparatus of the present invention. Theportable computer1 comprises a computermain body2 and adisplay unit3. The computermain body2 has a flat box-shapedhousing4. Thehousing4 comprises abottom wall4a, anupper wall4b, right and left side walls4c, afront wall4dand a rear wall (not shown). Theupper wall4bsupports akeyboard5.
• Thedisplay unit3 comprises a flat box-shapeddisplay housing6 and a liquidcrystal display panel7. Thedisplay housing6 is supported on the rear end portion of thehousing4 with hinges (not shown). The liquidcrystal display panel7 is contained in thedisplay housing6. The liquidcrystal display panel7 has ascreen7a, which displays images. Thescreen7ais exposed to the outside of thedisplay unit3 through anopening8 formed in the front surface of thedisplay housing6.
• As shown inFIG. 2, thehousing4 contains a printedwiring board10 and acooling unit11. Anelectronic component12 as a heat generating component is mounted on an upper surface of the printedwiring board10. Theelectronic component12 is, for example, a CPU serving as the nerve center of theportable computer1. Theelectronic component12 produces a very large amount of heat during operation, due to an increase in the processing speed and functions. Theelectronic component12 requires cooling to maintain its stable operation.
• The coolingunit11 is provided to cool theelectronic component12. The coolingunit11 comprises a heat-receivingportion13, a coolingfan14 serving as a heat-radiating portion, and aheat pipe15.
• The heat-receivingportion13 has a plate shape larger than theelectronic component12, and is formed of a metal material having excellent thermal conductivity, such as aluminum alloy. The heat-receivingportion13 is fixed on the printedwiring board10 so as to cover theelectronic component12. A lower surface of the heat-receivingportion13 is thermally connected to theelectronic component12. The heat-receivingportion13 has afan supporting portion16. Thefan supporting portion16 projects in a direction away from theelectronic component12 and forms one unitary piece with the heat-receivingportion13.
• The coolingfan14 comprises afan casing18 and animpeller19. Thefan casing18 is formed of a metal material having excellent thermal conductivity, such as aluminum alloy. Thefan casing18 has anupper wall20 and aperipheral wall21. Theupper wall20 is opposed to thefan supporting portion16. Theperipheral wall21 extends downward from a peripheral edge of theupper wall20. A lower end portion of theperipheral wall21 is fixed on the upper surface of thefan supporting portion16 with screws.
• In the first embodiment, the heat-receivingportion13 and thefan casing18 are connected via thefan supporting portion16. Therefore, a portion of the heat provided by theelectronic component12 is conveyed from the heat-receivingportion13 to thefan casing18 through thefan supporting portion16. Thus, thefan casing18 also functions as a heat radiator.
• Theperipheral wall21 of thefan casing18 has a flat connectingsurface21a. The connectingsurface21astands on the upper surface of thefan supporting portion16. The connectingsurface21aand the upper surface of thefan supporting portion16 have such positional relationship that they are substantially perpendicular to each other.
• Theimpeller19 is supported by theupper wall20 of thefan casing18 with aflat motor22 interposed therebetween. Theflat motor22 rotates theimpeller19 when, for example, the power of theportable computer1 is turned on or the temperature of theelectronic component12 reaches a predetermined value.
• Theupper wall20 of thefan casing18 has anintake23a. Thefan supporting portion16 has anintake23b. Theintakes23aand23bare opened to a rotation center portion of theimpeller19, and opposed to each other with theimpeller19 interposed therebetween. Theperipheral wall21 of thefan casing18 has anoutlet24. Theoutlet24 is opposed to a circumferential portion of theimpeller19, and communicates withexhaust ports25 opened at the side wall4cof thehousing4.
• When theimpeller19 is rotated, the air inside thehousing4 is taken into the rotation center portion of theimpeller19 through theintakes23aand23b. The air is emitted as cooling air from the circumferential portion of theimpeller19 by centrifugal force. The cooling air cools thefan casing18 and thefan supporting portion16, and is discharged from theoutlet24 to theexhaust ports25.
• Theheat pipe15 comprises a substantially straight circuit operating as acontainer30. According to this embodiment of the invention, thecontainer30 is elongated and hollow so as to be pipe-shaped. Thecontainer30 is formed of a metal material having excellent heat conductivity, such as aluminum, stainless steel or copper, and basically has a circular cross section. As shown inFIGS. 4 and 6, awick31 comprising a plurality of grooves is formed on an internal surface of thecontainer30. Thewick31 extends along the axis of thecontainer30, with the grooves thereof arranged in the circumferential direction of thecontainer30 at regular intervals. An operating fluid such as ammonia, alcohol, and water, is sealed in thecontainer30.
• As shown inFIG. 3, thecontainer30 comprises a heat-receivingend portion32, a heat-radiatingend portion33, and amiddle portion34. The heat-receivingend portion32, the heat-radiatingend portion33 and themiddle portion34 are arranged in-line in the axial direction of thecontainer30. The heat-receivingend portion32 is located at one end of thecontainer30, and extends over a fixed length in the axial direction of thecontainer30. The heat-receivingend portion32 is formed by flattening the one end of thecontainer30, and thus, has a (flat) cross section elongated in the lateral direction as shown inFIG. 4. In other words, the heat-receivingend portion32 has two flat heat receiving surfaces32aand32b, and a pair ofedge portions32cand32d. The heat receiving surfaces32aand32bare arranged in parallel so as to be opposed to each other in the radial direction of thecontainer30. Each of theedge portions32cand32dspreads over the heat receiving surfaces32aand32b, and extends in the axial direction of thecontainer30.
• The heat-radiatingend portion33 is located at the other end of thecontainer30, and extends over a fixed length in the axial direction of thecontainer30. The heat-radiatingend portion33 is formed by flattening the other end of thecontainer30, and thus, has a (flat) cross section elongated in the vertical direction as shown inFIG. 5. In other words, the heat-radiatingend portion33 has two flatheat radiating surfaces33aand33b, and a pair ofedge portions33cand33d. The heat radiating surfaces33aand33bare arranged in parallel so as to be opposed to each other in the radial direction of thecontainer30. Each of theedge portions33cand33dspreads over theheat radiating surfaces33aand33b, and extends in the axial direction of thecontainer30.
• The heat-radiatingend portion33 is flattened in a direction different from a direction in which the heat-receivingend portion32 is flattened. In the first embodiment, flattened portions of the heat-radiatingend portion33 and those of the heat-receivingend portion32 are arranged in positions twisted by 90° in the circumferential direction of thecontainer30. Thereby, the orientation of the heat receiving surfaces32aand32band the orientation of theheat radiating surfaces33aand33bare different from each other by approximately 90°.
• Themiddle portion34 connects the heat-receivingend portion32 and the heat-radiatingend portion33, being interposed between them. As shown inFIG. 6, themiddle portion34 has a circular or oval cross section, maintaining the basic cross section shape of thecontainer30. The term “circular” in the present invention is defined as including shapes of a circle, an ellipse, and an oval.
• As shown inFIG. 3, thecontainer30 has a pair ofboundary portions35 and36. Oneboundary portion35 is located between the heat-receivingend portion32 and themiddle portion34. The cross section of theboundary portion35 gradually changes from a flat shape on the side of the heat-receivingend portion32 to a circular shape on the side of themiddle portion34. Theother boundary portion36 is located between the heat-radiatingend portion33 and themiddle portion34. The cross section of theboundary portion36 gradually changes from a flat shape on the side of the heat-radiatingend portion33 to a circular shape on the side of themiddle portion34.
• Thecontainer30 of theheat pipe15 extends over the upper surface of the heat-receivingportion13 and thefan casing18. The oneheat receiving surface32aof the heat-receivingend portion32 is thermally connected to the upper surface of the heat-receivingportion13 by soldering or the like. Theheat receiving surface32ais opposed to theelectronic component12 with the heat-receivingportion13 interposed therebetween.
• The oneheat radiating surface33aof the heat-radiatingend portion33 is thermally connected to the connectingsurface21aof thefan casing18 by soldering or the like. The connectingsurface21aof thefan casing18 and the upper surface of theheat receiving surface13 have such a positional relationship that they are orthogonal to each other. In conformity with this, in theheat pipe15, the orientations of the heat-receivingend portion32 and the heat-radiatingend portion33 are shifted by 90° in the circumferential direction of thecontainer30. Therefore, it is possible to thermally connect the heat-radiatingend portion33 of theheat pipe15 to the connectingsurface21aof thefan casing18, in the state where the heat-receivingend portion32 of theheat pipe15 is thermally connected to the upper surface of the heat-receivingportion13.
• When theelectronic component12 generates heat, the heat of theelectronic component12 is transmitted to the heat-receivingportion13. The heat-receivingend portion32 of theheat pipe15 receives the heat of theelectronic component12 from the heat-receivingportion13. Thereby, the operating fluid inside the heat-receivingend portion32 is heated and vaporized. This vapor flows from the heat-receivingend portion32 toward the heat-radiatingend portion33 through themiddle portion34. The vapor guided into the heat-radiatingend portion33 is condensed therein. Heat liberated by this condensation is diffused by heat conduction from the heat-radiatingend portion33 to thefan casing18, and radiated from the surface of thefan casing18.
• The operating fluid liquefied in the heat-radiatingend portion33 is conveyed through thewick31 by capillary action and returns to the heat-receivingend portion32. The operating fluid returned to the heat-receivingend portion32 receives heat of theelectronic component12 again. Heat of theelectronic component12 is conveyed to thefan casing18 by the repeated evaporation and condensation of the operating fluid.
• According to the above structure, the heat-radiatingend portion33 of theheat pipe15 is flattened in a direction twisted by 90° with respect to the heat-receivingend portion32 of theheat pipe15 in the circumferential direction of thecontainer30. Therefore, it is possible to solder the heat-radiatingend portion33 to the connectingsurface21aof thefan casing18 standing on the heat-receivingportion13, in the state where the heat-receivingend portion32 is soldered to the upper surface of the heat-receivingportion13.
• In other words, supposing that the heat-receivingend portion32 and the heat-radiatingend portion33 of theheat pipe15 are flattened in the same direction, in the state where the heat-receivingend portion32 is soldered to the heat-receivingportion13, the flat portions of the heat-radiatingend portion33 are perpendicular to the connectingsurface21aof thefan casing18. Therefore, the flat surface of the heat-radiatingend portion33 cannot be brought into contact with the connectingsurface21a. Consequently, it is required to change the shape of thefan casing18 or mounting orientation of the coolingfan14.
• On the other hand, according to the above structure, the heat-radiatingend portion33 of theheat pipe15 can be thermally connected to thefan casing18, without changing the shape of thefan casing18 and the mounting orientation of the coolingfan14. Therefore, the shape of thefan casing18 is not restricted, and the flexibility in the mounting orientation of thefan casing18 with respect to the heat-receivingportion13 is increased.
• Further, themiddle portion34 connecting the heat-receivingend portion32 and the heat-radiatingend portion33 still has a circular cross section. Therefore, thewick31 on the internal surface of themiddle portion34 is neither deformed nor crushed. Thus, the operating fluid smoothly flows between the heat-receivingend portion32 and the heat-radiatingend portion33, and heat of theelectronic component12 is efficiently conveyed to thefan casing18.
• In the first embodiment, the heat-receivingend portion32 and the heat-radiatingend portion33 of the container are soldered to the heat-receiving portion and the fan casing, respectively. However, the present invention is not limited to this structure. For example, a structure may be adopted wherein a fitting groove is formed on each of the heat-receiving portion and thefan casing18 and the heat-receivingend portion32 and the heat-radiatingend portion33 of the container are fitted in the respective grooves.
• In addition, the wick is not limited to grooves formed on the internal surface of the container. For example, a wick material formed of glass fiber or net-shaped thin line material may be fitted inside the container.
• The present invention is not limited to the first embodiment.FIG. 7 discloses a second embodiment of the invention.
• The second embodiment is different from the first embodiment mainly in the structure of acooling unit41. The coolingunit41 has a heat-receivingportion42 and a heat-radiatingportion43. The heat-receivingportion42 and the heat-receivingportion43 are separated from each other. The heat-receivingportion42 has a flat board form with a size corresponding to anelectronic component12, and is formed of a metal material having excellent heat conductivity, such as aluminum alloy. The heat-receivingportion42 has a flat connectingsurface42aon the side reverse to the side on which theelectronic component12 exists.
• The heat-radiatingportion43 comprises a plurality ofheat radiating fins44, and aframe45 supporting theheat radiating fins44. Theheat radiating fins44 are arranged in parallel at regular intervals. The cooling air flows between adjacentheat radiating fins44. Theframe45 has a flat connectingsurface45a. The connectingsurface45aextends in a direction in which theheat radiating fins44 are arranged. The connectingsurface45aof theframe45 and the connectingsurface42aof the heat-receivingportion42 have such positional relationship that they are orthogonal to each other.
• The heat-receivingportion42 and the heat-radiatingportion43 are thermally connected by aheat pipe15 having the same structure as in the first embodiment. A heat-receivingend portion32 of theheat pipe15 is soldered to the connectingsurface42aof the heat-receivingportion42. A heat-radiatingend portion33 of theheat pipe15 is soldered to the connectingsurface45aof theframe45.
• According to the above structure, the heat-receivingportion42 and the heat-radiatingportion43 can be thermally connected by theheat pipe15, even if the connectingsurface42aof the heat-receivingportion42 is orthogonal to the connectingsurface45aof the heat-radiatingportion43. Therefore, it is possible to efficiently convey heat of theelectronic component12, which has been transmitted to the heat-receivingportion42, to the heat-radiatingportion43 by theheat pipe15.
• FIG. 8 discloses a third embodiment of the invention.
• The third embodiment is different from the second embodiment in structure of a heat-radiatingportion51. The other parts of the structure of acooling unit41 are the same as those in the second embodiment.
• As shown inFIG. 8, the heat-radiatingportion51 has a board shape with almost the same size as that of a heat-receivingportion42, and is formed of a material having excellent heat conductivity, such as aluminum alloy. The heat-radiatingportion51 has a flat connectingsurface51a. The connectingsurface51aof the heat-radiatingportion51 and a connectingsurface42aof the heat-receivingportion42 have such a positional relationship that they are orthogonal to each other. A heat-radiatingend portion33 of theheat pipe15 is soldered to the connectingsurface51aof the heat-radiatingportion51.
• FIG. 9 discloses a fourth embodiment of the invention.
• The fourth embodiment is an extension of the second embodiment. As shown inFIG. 9, aheat pipe15 has abent portion61, which has, an arc-shaped bend, in amiddle portion34 of itscontainer30. For example, the bend is approximately ninety degrees (90°) for this embodiment. By the existence of thebent portion61, a heat-receivingend portion32 and a heat-radiatingend portion33 of theheat pipe15 extend in directions orthogonal to each other. In other words, an axis 0₁of the heat-receivingend portion32 and an axis 0₂of the heat-radiatingend portion33 cross at right angles in a position corresponding to thebent portion61. Therefore, the heat conveying direction of theheat pipe15 according to the fourth embodiment turns by approximately 90°.
• Further, in the fourth embodiment, the heat-receivingend portion32 and the heat-radiatingend portion33 are shifted from each other by a 45° twist in a circumferential direction of thecontainer30. Thereby, the orientation of aheat receiving surface32aof the heat-receivingend portion32 is different from the orientation of aheat radiating surface33aof the heat-radiatingend portion33.
• A heat-radiatingportion43 of the coolingunit41 comprises a plurality ofheat radiating fins62 and aframe63 supporting theheat radiating fins62. Eachheat radiating fin62 has a flat plate shape. Theheat radiating fins62 are arranged in parallel at regular intervals, and stand in a vertical direction. Theframe63 has a connectingsurface63a. The connectingsurface63aextends in a direction in which theheat radiating fins62 are arranged, and is inclined by about 45° with respect to the standing direction of theheat radiating fins62. The angle of inclination of the connectingsurface63acorresponds to a twist angle of the heat-radiatingend portion33 with respect to the heat-receivingend portion32 of theheat pipe15. The heat-radiatingend portion33 of theheat pipe15 is soldered to the connectingsurface63aof theframe63.
• According to the above structure, thecontainer30 of theheat pipe15 is bent in the position of themiddle portion34 which keeps a circular cross section. Therefore, it is possible to reduce the radius of thebent portion61 in comparison with the case of bending a flat container. Therefore, the heat-receivingend portion32 and the heat-radiatingend portion33 are close to each other. This makes the coolingunit41 compact, and enables reduction in the space necessary for setting thecooling unit41.
• Besides, thebent portion61 of theheat pipe15 is located in themiddle portion34 having a circular cross section. This prevents deformation and crush of thewick31 on the internal surface of thebent portion61. It is thus possible to efficiently convey heat from the heat-receivingportion42 to the heat-radiatingportion43.
• FIG. 10 discloses a fifth embodiment of the present invention.
• The fifth embodiment is a further extension of the third embodiment. The basic structure of acooling unit41 of the fifth embodiment is the same as that in the third embodiment.
• As shown inFIG. 10, aheat pipe15 has astep portion71 in amiddle portion34 of acontainer30. Thestep portion71 is bent like a crank to couple the openings of thestep portion71 to corresponding laterally offsetboundary portions35 and36. The presence of thestep portion71 generates difference in level between a heat-receivingend portion32 and a heat-radiatingend portion33, and the heat-receivingend portion32 and the heat-radiatingend portion33 are displaced from each other in the radial direction of thecontainer30.
• According to the above structure, thecontainer30 of theheat pipe15 is bent like a crank in the position of themiddle portion34 which keeps a circular cross section. It prevents thewick31 on the internal surface of thecontainer30 from being deformed and crushed, in comparison with the case of bending a flat container. It is thus possible to efficiently convey heat from the heat-receivingportion42 to the heat-radiatingportion43.
• FIG. 11 discloses a sixth embodiment of the present invention.
• The sixth embodiment is an extension of the fourth embodiment. The basic structure of acooling unit41 of the sixth embodiment is the same as that in the fourth embodiment.
• As shown inFIG. 11, aheat pipe15 has astep portion81 in amiddle portion34 of acontainer30. Thestep portion81 is bent like a crank, and located next to abent portion61. The presence of thestep portion81 generates difference in level between a heat-receivingend portion32 and a heat-radiatingend portion33, and the heat-receivingend portion32 and the heat-radiatingend portion33 are displaced from each other in the radial direction of thecontainer30. Therefore, theheat pipe15 of this embodiment is bent in three dimensions.
• FIGS. 12, 13A and13B disclose a seventh embodiment of the present invention.
• The seventh embodiment is different from the first embodiment in the form of aheat pipe15. The other parts of the basic structure of acooling unit11 in the seventh embodiment are the same as those in the first embodiment.
• Theheat pipe15 has amiddle portion91 connecting a heat-receivingend portion32 and a heat-radiatingend portion33. The heat-receivingend portion32 and the heat-radiatingend portion33 have a positional relationship in which they are displaced by 90° in the circumferential direction of acontainer30. The orientation of heat receiving surfaces32aand32bis different by 90° from the orientation ofheat radiating surfaces33aand33b. This is the same as in the first embodiment.
• As shown inFIGS. 13A and 13B, themiddle portion91 of theheat pipe15 has an angular pipe shape. Themiddle portion91 has a pair offirst surfaces92aand92b, and a pair ofsecond surfaces93aand93b. Onefirst surface92aconnects oneheat receiving surface32aof the heat-receivingend portion32 and oneedge portion33cof the heat-radiatingend portion33. Therefore, theedge portion33cof the heat-radiatingend portion33 is connected with theheat receiving surface32awith thefirst surface92ainterposed therebetween.
• The otherfirst surface92bconnects the otherheat receiving surface32bof the heat-receivingend portion32 and theother edge portion33dof the heat-radiatingend portion33. Thefirst surface92bis located on the reverse side of thefirst surface92a. The twofirst surfaces92aand92bare gradually inclined so as to move away from each other, in the direction from the heat-receivingend portion32 to the heat-radiatingend portion33. Therefore, thefirst surfaces92aand92bare not parallel with each other, and connect to the heat receiving surfaces32aand32b, respectively, of the heat-receivingend portion32.
• Thesecond surface93aconnects oneheat radiating surface33aof the heat-radiatingend portion33 and oneedge portion32cof the heat-receivingend portion32. In other words, theedge portion32cof the heat-receivingend portion32 is connected with theheat radiating surface33awith thesecond surface93ainterposed therebetween.
• The othersecond surface93bconnects the otherheat radiating surface33bof the heat-radiatingend portion33 and theother edge portion32dof the heat-receivingend portion32. Therefore, theedge portion32dof the heat-receivingend portion32 is connected with theheat radiating surface33bwith thesecond surface93binterposed therebetween.
• The onesecond surface93ais located on the reverse side of the othersecond surface93b. The twosecond surfaces93aand93bare gradually declined so as to move closer to each other, in the direction from the heat-receivingend portion32 to the heat-radiatingend portion33. Therefore, thesecond surfaces93aand93bare not parallel with each other, and connect with theheat radiating surfaces33aand33b, respectively, of the heat-radiatingend portion33.
• According to the above structure, themiddle portion91 connecting the heat-receivingend portion32 and the heat-radiatingend portion33 has an angular pipe shape having thefirst surfaces92aand92bnot being parallel and thesecond surfaces93aand93bnot being parallel. This prevents deformation and crush ofwick31 on the internal surface of themiddle portion91. It is thus possible to efficiently convey heat from a heat-receivingportion42 to a heat-radiatingportion43, although the orientations of the heat-receivingend portion32 and the heat-radiatingend portion33 are displaced from each other in the circumferential direction of thecontainer30.
• FIGS. 14A and 14B disclose an eighth embodiment of the present invention.
• The eighth embodiment is different from the seventh embodiment in the form of amiddle portion91 of aheat pipe15. The other parts of the structure of theheat pipe15 in the eighth embodiment is the same as those in the seventh embodiment.
• As shown inFIG. 14B, onefirst surface92aof themiddle portion91 is located on the same plane as oneheat receiving surface32aof a heat-receivingend portion32 and oneedge portion33cof a heat-radiatingend portion33. The otherfirst surface92bis gradually inclined to move away from thefirst surface92a, in the direction from the heat-receivingend portion32 to the heat-radiatingend portion33.
• Onesecond surface93aof themiddle portion91 is inclined to become gradually close to the othersecond surface93b, in the direction from the heat-receivingend portion32 to the heat-radiatingend portion33. The othersecond surface93bof themiddle portion91 is located on the same plane as the otherheat radiating surface33bof the heat-radiatingend portion33 and theother edge portion32dof the heat-receivingend portion32.
• Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Claims (29)

1. A heat pipe comprising:

a sealed container including an operating fluid, the container comprises a heat-receiving end portion flattened in a first direction, a heat-radiating end portion flattened in a second direction differing from the first direction, and a middle portion having a non-flattened cross section and connecting the heat-receiving end portion and the heat-radiating end portion; and

a wick provided inside the container.

2. A heat pipe according toclaim 1, wherein the middle portion of the container has a circular cross section.

3. A heat pipe according toclaim 1, wherein the middle portion of the container includes an arc-shaped bent portion.

4. A heat pipe according toclaim 1, wherein the middle portion of the container includes a first opening for coupling to the heat-receiving end portion and a second opening for coupling to the heat-radiating end portion, the first opening being laterally offset from the second opening.

5. A heat pipe according toclaim 1, wherein the middle portion of the container being a conduit including an arc-shaped portion coupled to a crank-shaped portion having a first opening laterally offset from a second opening.

6. A heat pipe according toclaim 1, wherein the heat-receiving end portion of the container has two parallel heat receiving surfaces, the heat-radiating end portion of the container has two parallel heat radiating surfaces, and orientation of the heat-receiving surfaces is different from orientation of the heat-radiating surfaces in a circumferential direction of the container.

7. A heat pipe according toclaim 1, wherein the wick is situated inside the middle portion of the container.

8. A heat pipe comprising:

a sealed container housing an operating fluid, the container comprises a heat-receiving end portion flattened in a first direction, a heat-radiating end portion flattened in a second direction different from the first direction, and an arc-shaped middle portion having a circular cross section coupled between the heat-receiving end portion and the heat-radiating end portion; and

a wick provided inside the container.

9. A heat pipe according toclaim 8, wherein the heat-receiving end portion and the heat-radiating end portion extends in directions different from each other, with the middle portion interposed therebetween.

10. A heat pipe according toclaim 8, wherein the wick is situated inside the middle portion of the container.

11. A heat pipe comprising:

a sealed container including an operating fluid, the container comprises a heat-receiving end portion having a cross section elongated in a first direction, a heat-radiating end portion having a cross section elongated in a second direction different than the first direction, and a middle portion coupling the heat-receiving end portion and the heat-radiating end portion, the heat-receiving end portion, the heat-radiating end portion and the middle portion are arranged in-line, each of the heat-receiving end portion and the heat-radiating end portion has two surfaces substantially in parallel, and the middle portion includes a first pair of non-parallel surfaces coupled to the two respective surfaces of the heat-receiving end portion and a second pair of non-parallel surfaces coupled to the two respective surfaces of the heat-radiating end portion; and

a wick provided inside the container.

12. A heat pipe according toclaim 11, wherein each of the heat-receiving end portion and the heat-radiating end portion has a pair of edge portions extending in an axial direction of the container, the edge portions of the heat-receiving end portion are coupled to the two respective surfaces of the heat-radiating end portion with the second pair of non-parallel surfaces of the middle portion interposed therebetween, and the edge portions of the heat-radiating end portion are coupled to the two respective surfaces of the heat-receiving end portion with the first pair of non-parallel surfaces of the middle portion interposed therebetween.

13. A cooling unit comprising:

a heat-receiving portion thermally connected to a heat generating component;

a heat-radiating portion radiating heat from the heat generating component; and

a heat pipe which conveys heat by the heat generating component from the heat-receiving portion to the heat-radiating portion, the heat pipe comprising a pipe-shaped container sealed to house a heat-conveying operating fluid and a wick, the container comprises a heat-receiving end portion having a cross section elongated in a first direction, a heat-radiating end portion having a cross section elongated in a second direction differing from the first direction, and a middle portion connecting the heat-receiving end portion and the heat-radiating end portion, the middle portion having a circular cross section.

14. A cooling unit according toclaim 13, wherein the heat-receiving portion has a supporting portion which supports the heat-radiating portion.

15. A cooling unit according toclaim 13, wherein the heat-radiating portion comprises a fan casing thermally connected to the heat-radiating end portion of the heat pipe and an impeller contained in the fan casing.

16. A cooling unit according toclaim 15, wherein the fan casing includes a peripheral wall extending in a direction perpendicular to the heat-receiving portion and thermally connected to the heat-radiating end portion of the heat pipe.

17. A cooling unit according toclaim 13, wherein the heat-receiving end portion of the container of the heat pipe has two heat receiving surfaces substantially in parallel with each other, the heat-radiating end portion has two heat radiating surfaces substantially in parallel with each other, and orientation of the heat receiving surfaces is different from orientation of the heat radiating surfaces in a circumferential direction of the container.

18. A cooling unit according toclaim 13, wherein the middle portion of the container includes an arc-shaped portion.

19. A cooling unit according toclaim 13, wherein the middle portion of the container includes a first portion for coupling to the heat-receiving end portion and a second portion for coupling to the heat-radiating end portion, the first portion being laterally offset from the second portion.

20. A cooling unit according toclaim 13, wherein the middle portion of the container being a conduit including an arc-shaped first portion coupled to a second portion having a first opening laterally offset from a second opening.

21. A cooling unit according toclaim 13, wherein the heat-radiating portion includes a plurality of heat radiating fins arranged with regular intervals and thermally connected to the heat-radiating end portion of the heat pipe.

22. A cooling unit comprising:

a heat-receiving portion adapted to be thermally connected to a heat generating component;

a heat-radiating portion adapted to radiate heat from the heat generating component; and

a heat pipe for conveying the heat of the heat generating component from the heat-receiving portion to the heat-radiating portion, the heat pipe comprising a container formed as a sealed conduit including a heat-conveying operating fluid and a wick inside the container, the container comprises a flat heat-receiving end portion having a cross section elongated in a first direction, a flat heat-radiating end portion having a cross section elongated in a second direction different than the first direction, and a middle portion connecting the heat-receiving end portion and the heat-radiating end portion and having a circular cross section, the middle portion bent into an arc.

23. A cooling unit according toclaim 22, wherein the heat-receiving end portion and the heat-radiating end portion extend in directions different from each other, with the middle portion interposed therebetween.

24. A cooling unit comprising:

a heat-receiving portion thermally connected to a heat generating component;

a heat-radiating portion adapted to radiate heat from the heat generating component; and

a heat pipe which conveys heat from the heat-receiving portion to the heat-radiating portion, the heat pipe comprising a sealed, pipe-shaped container including a heat-conveying operating fluid and a wick housed inside the container, the container comprises a flat heat-receiving end portion with a cross section elongated in a first direction, a flat heat-radiating end portion having a cross section elongated in a second direction differing from the first direction, and a middle portion connecting the heat-receiving end portion and the heat-radiating end portion, the heat-receiving end portion, the heat-radiating end portion and the middle portion are arranged in-line, each of the heat-receiving end portion and the heat-radiating end portion has two surfaces substantially in parallel, and the middle portion has a first pair of non-parallel surfaces coupled to the two respective surfaces of the heat-receiving end portion, and a second pair of non-parallel surfaces coupled to the two respective surfaces of the heat-radiating end portion.

25. A cooling unit according toclaim 24, wherein each of the heat-receiving end portion and the heat-radiating end portion includes a pair of edge portions extending in an axial direction of the container, the edge portions of the heat-receiving end portion are coupled to the two respective surfaces of the heat-radiating end portion with the second pair of non-parallel surfaces of the middle portion interposed therebetween, and the edge portions of the heat-radiating end portion are coupled to the two respective surfaces of the heat-receiving end portion with the respective first pair of non-parallel surfaces of the middle portion interposed therebetween.

26. An electronic apparatus comprising:

a housing having a heat generating component;

a heat-receiving portion contained in the housing and thermally connected to the heat generating component;

a heat-radiating portion adapted to radiate heat from the heat generating component; and

a heat pipe which conveys the heat from the heat-receiving portion to the heat-radiating portion, the heat pipe comprising a pipe-shaped container in which a heat-conveying operating fluid is sealed, and a wick provided inside the container, the container comprises a flat heat-receiving end portion, a heat-radiating end portion being flattened in a direction different from that of the heat-receiving end portion, and a middle portion connecting the heat-receiving end portion and the heat-radiating end portion and having a circular cross section.

27. An electronic apparatus according toclaim 26, wherein the middle portion of the container of the heat pipe is bent into an arc shaped portion.

28. An electronic apparatus according toclaim 26, wherein the housing has an exhaust port, the heat-radiating portion includes a fan casing thermally connected to the heat-radiating end portion of the container, the fan casing includes an outlet and contained in the housing with the outlet opposed to the exhaust port.

29. An electronic apparatus comprising:

a housing including a heat generating component and a heat-receiving portion thermally connected to the heat generating component;

a heat-radiating portion to radiate heat of the heat generating component; and

a heat pipe which conveys the heat from the heat-receiving portion to the heat-radiating portion, the heat pipe comprises a pipe-shaped container in which a heat-conveying operating fluid is sealed, and a wick provided inside the container, the container having a flat heat-receiving end portion, a heat-radiating end portion being flattened in a direction different from that of the heat-receiving end portion, and a middle portion connecting the heat-receiving end portion and the heat-radiating end portion, the heat-receiving end portion, the heat-radiating end portion and the middle portion are arranged in-line, each of the heat-receiving end portion and the heat-radiating end portion has two surfaces substantially in parallel, and the middle portion has two first non-parallel surfaces connecting with the two respective surfaces of the heat-receiving end portion, and two second non-parallel surfaces connecting with the two respective surfaces of the heat-radiating end portion.

Images