Heat pipe excellent in reflux characteristic

• US 20040177946A1
• Filed: 02/13/2004
• Published: 09/16/2004
• Est. Priority Date: 02/17/2003
• Status: Active Grant

• Current Assignee: Lenovo PC International Limited (Lenovo Group Ltd.)
• Original Assignee: Fujikura Limited, International Business Machines Corporation
• Inventors: Agata, Hiroaki, Mochizuki, Masataka, Kiyooka, Fumitoshi, Mashiko, Koichi, Kawahara, Youji
• Granted Patent: US 7,261,142 B2
• Time in Patent Office: Days
• US Class Current: 165/104.11
• CPC Class Codes: F28D 15/0233 the conduits having a particular shape, e.g. non-circular cross-section, annular F28D15/0241, F28D15/0266 take precedence
• CPC Class Codes: F28D 15/046 characterised by the material or the construction of the capillary structure

Abstract

A heat pipe wherein a condensable liquid phase working fluid is encapsulated in a container sealed in air-tight condition; wherein the wick composed of the porous body for refluxing the liquid phase working fluid by a capillary pressure is provided in the container; wherein a part of the container functions as an evaporating part for evaporating the working fluid by means of inputting the heat from outside; and wherein another part of the container functions as a condensing part for condensing a vapor of the working fluid by means of radiating the heat to the outside; comprises a direct reflux flow passage for flowing the liquid phase working fluid to the evaporating part, which has a flow cross-sectional area greater than that of a cavity formed in the porous body.

Claims

1. A heat pipe comprising a direct reflux flow passage having a flow cross-sectional area greater than that of a cavity formed in a wick;

wherein the condensable, liquid phase working fluid is encapsulated in a container sealed in an air-tight condition;

wherein the wick provided in the container is composed of a porous body for refluxing the condensable, liquid phase working fluid by a capillary pressure to an evaporating part of the container;

wherein a part of the container functions as the evaporating part for evaporating the condensable, liquid phase working fluid by means of inputting heat from outside; and

wherein another part of the container functions as a condensing part for condensing a vapor of the condensed working fluid by means of radiating heat to the outside.

2. A heat pipe according to claim 1,

wherein the direct reflux flow passage includes a plurality of flow paths extending from the evaporating part to a plurality of portions on the side of the condensing part.

3. A heat pipe according to claim 1,

wherein the direct reflux flow passage includes a thin slit or thin slits formed on the surface of the porous body.

4. A heat pipe according to claim 2,

wherein the direct reflux flow passage includes thin slits formed on the surface of the porous body.

5. A heat pipe according to claim 3,

wherein a clearance between the thin slits in the width direction of the porous body changes flexibly in accordance with the width of the porous body.

6. A heat pipe according to claim 1,

wherein the direct reflux flow passage is formed between the porous body and an inner face of the container where the porous body is mounted.

7. A heat pipe according to claim 6,

wherein the direct reflux flow passage comprises a concave slit formed on the surface of the porous body disposed opposite to a concave slit formed on the inner face of the container.

8. A heat pipe according to claim 1,

wherein a cross-sectional shape of the direct reflux flow passage is selected from the group consisting of a triangular shape, a circular shape, a trapezoidal shape, a semicircular shape, and a square shape.

9. A heat pipe according to claim 5,

wherein a cross-sectional shape of the direct reflux flow passage is selected from the group consisting of a triangular shape, a circular shape, a trapezoidal shape, a semicircular shape, and a square shape.

10. A heat pipe according to claim 1,

wherein the encapsulating amount of the condensable liquid phase working fluid is governed by:

(Volume of wick×

porosity+predetermined value α

).

11. A heat pipe according to claim 1,

wherein the wick is composed of a porous sintered compact, and its material is copper powder or ceramic powder.

12. A heat pipe according to claim 1,

wherein a part of the container functions as an evaporating part for evaporating the condensable, liquid phase working fluid by means of an exothermic element contacted or joined to the evaporating part in a heat transmittable manner.

13. A heat pipe according to claim 1,

wherein the direct reflux flow passage includes a plurality of flow paths extending from the plurality of portions of the condensing part side to the evaporating part.

14. A heat pipe according to claim 1,

wherein a clearance between the plurality of flow paths on the evaporating part side is wider than that on the condensing part side in connection with that the width of the wick is wider on the evaporating part side, in order to arrange the reflux flow passages evenly in the width direction of the wick.

15. A heat pipe according to claim 1,

wherein a dent is created in the liquid surface of the condensable, liquid phase working fluid at the portion corresponding to the reflux flow passage, and a vapor flow passage is secured therein.

16. A heat pipe according to claim 2,

wherein dents are created in the liquid surface of the condensable, liquid phase working fluid at the portions corresponding to the plurality of flow paths of the reflux flow passage, and vapor flow passages are secured therein.

17. A heat pipe according to claim 1,

wherein the inputted heat from outside to the evaporating part is 25 to 45 W (watt).

18. A heat pipe according to claim 1,

wherein a direct reflux flow passage has a flow resistance less than that of a cavity formed in a wick composed of a porous body.