HEAT PIPE

Abstract

A heat pipe includes a casing having an inner wall. A plurality of protrusions are radially formed on the inner wall of the casing. The plurality of protrusions are spaced from each other and extend longitudinally from one end of the casing to the other end of the casing. A main groove is defined between every two adjacent protrusions. The protrusions each define a plurality of first auxiliary grooves and a plurality of second auxiliary grooves being alternatively arranged with respect to each other along a longitudinal direction of the casing. The first auxiliary and the second auxiliary grooves each communicate two adjacent main grooves. The first auxiliary grooves each are inclined at an angle with respect to a longitudinal axis of the casing, and the second auxiliary grooves each are inclined at another different angle with respect to the longitudinal axis of the casing.

Description

BACKGROUND

1. Technical Field

The present invention relates generally to a heat pipe, and particularly to a grooved heat pipe.

2. Description of Related Art

Heat pipes have excellent heat transfer performance due to their low thermal resistance, and are therefore an effective means for transfer or dissipation of heat from heat sources. Currently, heat pipes are widely used for removing heat from heat-generating components such as central processing units (CPUs) of computers. A heat pipe is usually a vacuum casing containing therein a working medium, which is employed to carry, under phase transitions between liquid state and vapor state, thermal energy from one section of the heat pipe (typically referring to as the “evaporator section”) to another section thereof (typically referring to as the “condenser section”). Preferably, a wick structure is provided inside the heat pipe, lining an inner wall of the casing, for drawing the working medium back to the evaporator section after it is condensed at the condenser section. The wick structure currently available for the heat pipe includes fine grooves integrally formed at the inner wall of the casing.

In operation, the evaporator section of the heat pipe is maintained in thermal contact with a heat-generating component. The working medium contained at the evaporator section absorbs heat generated by the heat-generating component and then turns into vapor. Due to the difference of vapor pressure between the two sections of the heat pipe, the generated vapor moves and thus carries the heat towards the condenser section where the vapor is condensed into condensate after releasing the heat into ambient environment by, for example, fins thermally contacting the condenser section. Due to the difference in capillary pressure which develops in the wick structure between the two sections, the condensate is then brought back by the wick structure to the evaporator section where it is again available for evaporation.

In order to draw the condensate back timely, the wick structure provided in the heat pipe is expected to provide a high capillary force and meanwhile generate a low flow resistance for the condensate. If the condensate is not quickly brought back from the condenser section, the heat pipe will suffer a dry-out problem at the evaporator section.

Therefore, it is desirable to provide a heat pipe with improved heat transfer capability.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a partially isometric view of a heat pipe in accordance with an exemplary embodiment of the present invention.

FIG. 2 is a longitudinally cross-sectional view of the heat pipe of FIG. 1, taken along line II-II thereof.

FIG. 3 is a stretch-out view of the heat pipe of FIG. 1.

FIG. 4 is a partially cross-sectional view of the heat pipe, taken along line IV-IV of FIG. 3.

DETAILED DESCRIPTION

Referring to FIGS. 1-2, a heat pipe 10 includes an elongated, round and tubular casing 11 containing a working fluid (not shown) therein, wherein only a section of the casing 11 is shown in the figures for illustrating the principle of the heat pipe 10.

The casing 11 is made of high thermally conductive material such as copper or aluminum. An inner wall 110 of the casing 11 defines a vapor channel 15 extending from a front end towards a rear end of the casing 11. A plurality of elongated protrusions 13 are radially and inwardly formed on the inner wall 110 of the casing 11 and circumferentially and evenly spaced from each other. The plurality of protrusions 13 each extend longitudinally from the front end towards the rear end of the casing 11. An elongated main groove 12 is defined between every two adjacent protrusions 13.

A plurality of first annular auxiliary channels 14 and a plurality of second annular auxiliary channels 17 are circumferentially defined in the plurality of protrusions 13. The plurality of first annular auxiliary channels 14 and the plurality of second annular auxiliary channels 17 are alternately arranged with respect to each other along a longitudinal direction of the casing 11, whereby each of the protrusions 13 is longitudinally divided into a plurality of sections.

Each of the first annular auxiliary channels 14 includes a plurality of first auxiliary grooves 18 being circumferentially defined in the plurality of protrusions 13. Each of the second annular auxiliary channels 17 includes a plurality of second auxiliary grooves 19 being circumferentially defined in the plurality of protrusions 13. The first auxiliary grooves 18 and the second auxiliary grooves 19 in each protrusion 13 are alternately arranged with respect to each other along the longitudinal direction of the casing 11 and evenly spaced from each other.

Each of the first auxiliary grooves 18 is inclined at an angle a with respect to a longitudinal axis of the casing 11, and each of the second auxiliary grooves 19 is inclined at another different angle β with respect to the longitudinal axis of the casing 11. In the illustrated embodiment, the angle α of the first auxiliary groove 18 is smaller than 90 degrees, and the another angle β of the second auxiliary groove 19 is larger than 90 degrees. The angle α of the first auxiliary groove 18 is complementary to the another angle β of the second auxiliary groove 19 (i.e., α plus β equaling 180 degrees). Preferably, the first auxiliary groove 18 and the second auxiliary groove 19 communicate with a main groove 12 are inclined along the longitudinal direction of the heat pipe 10 from an evaporator section (not shown) to a condenser section (not shown) thereof to two different sides of the main groove 12. The evaporator section is located at the front end of the casing 11, while the condenser section is located at the rear end of the casing 11. The first auxiliary grooves 18 and the second auxiliary grooves 19 are extended toward substantially opposite directions, whereas as shown in FIG. 3, the first auxiliary grooves 18 extend upwardly rightwards and the second auxiliary grooves 19 extend upwardly leftwards.

The first auxiliary groove 18 has a depth equal to the second auxiliary groove 19. Each of the first auxiliary groove 18 and the second auxiliary groove 19 has a depth greater than the main groove 12, as shown in FIG. 4. In alternative embodiments, each of the first auxiliary groove 18 and the second auxiliary groove 19 has a depth smaller than the main groove 12 or equal to the main groove 12.

The working fluid is saturated in the main grooves 12, the first auxiliary grooves 18 and the second auxiliary grooves 19. The working fluid is usually selected from a liquid such as water, methanol, or alcohol, which has a low boiling point. Thus, the working fluid can easily evaporate to vapor when it receives heat at the evaporator section of the heat pipe 10. The generated vapor moves via the vapor channel 15 towards the condenser section of the heat pipe 10. After the vapor releases the heat carried thereby and is condensed into the liquid in the condenser section, the liquid is brought back by a capillary action of the main grooves 12, the first auxiliary grooves 18 and the second auxiliary grooves 19 to the evaporator section of the heat pipe 10 for being available again for evaporation.

The first auxiliary grooves 18 and the second auxiliary grooves 19 defined in the protrusions 13 increase a receiving room for containing the working fluid therein, without increasing a size of the heat pipe 10. Meanwhile, the first auxiliary grooves 18 and the second auxiliary grooves 19 communicate a main groove 12 with an adjacent main groove 12, whereby the working fluid can flow between the two adjacent main grooves 12 via the first auxiliary grooves 18 and the second auxiliary grooves 19. Moreover, the first auxiliary grooves 18 and the second auxiliary grooves 19 function as supplemental wick structures to improve the capillary action of the heat pipe 10.

It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.

Claims

1. A heat pipe comprising:

a casing having an inner wall;

a plurality of protrusions radially formed on the inner wall of the casing, the plurality of protrusions being spaced from each other and extending longitudinally from one end of the casing to another end of the casing, a main groove being defined between every two adjacent protrusions, the protrusions each defining a plurality of first auxiliary grooves and a plurality of second auxiliary grooves therein, the first auxiliary grooves and the second auxiliary grooves in each of the protrusions being alternately arranged with respect to each other along a longitudinal direction of the casing, each of the first auxiliary grooves and the second auxiliary grooves communicating a main groove with an adjacent main groove, the first auxiliary grooves each being inclined at an angle with respect to a longitudinal axis of the casing, the second auxiliary grooves each being inclined at another different angle with respect to the longitudinal axis of the casing.

2. The heat pipe as claimed in claim 1, wherein the first auxiliary grooves and the second auxiliary grooves are inclinedly extended to two oppositely different directions along the longitudinal axis of the casing from the one end of the casing to the another end of the casing.

3. The heat pipe as claimed in claim 1, wherein the angle of the first auxiliary grooves is smaller than 90 degrees, and the another different angle of the second auxiliary grooves is larger than 90 degrees.

4. The heat pipe as claimed in claim 1, wherein the angle of the first auxiliary grooves is complementary to the another different angle of the second auxiliary grooves.

5. The heat pipe as claimed in claim 1, wherein each of the first auxiliary grooves and the second auxiliary grooves has a greater depth than the main groove.

6. A heat pipe comprising:

a casing having an inner wall;

a plurality of protrusions formed on the inner wall of the casing, the plurality of protrusions being spaced from each other and extending longitudinally through two opposite ends of the casing, a main groove being defined between two adjacent protrusions, a plurality of first annular auxiliary channels and a plurality of second annular auxiliary channels being defined in the plurality of protrusions, the first annular auxiliary channels and the second annular auxiliary channels being alternately arranged with respect to each other along a longitudinal direction of the casing, each of the first annular auxiliary channels comprising a plurality of first auxiliary grooves being circumferentially defined in the plurality of protrusions, each of the second annular auxiliary channels comprising a plurality of second auxiliary grooves being circumferentially defined in the plurality of protrusions, the first auxiliary grooves each being inclined at an angle with respect to a longitudinal axis of the casing, the second auxiliary grooves each being inclined at another different angle with respect to the longitudinal axis of the casing.

7. The heat pipe as claimed in claim 6, wherein the first auxiliary grooves and the second auxiliary grooves are inclinedly extended to two oppositely different directions along the longitudinal direction of the casing.

8. The heat pipe as claimed in claim 6, wherein the angle of the first auxiliary grooves is smaller than 90 degrees, the another different angle of the second auxiliary grooves is larger than 90 degrees.

9. The heat pipe as claimed in claim 6, wherein the angle of the first auxiliary grooves is complementary to the another different angle of the second auxiliary grooves.

10. The heat pipe as claimed in claim 6, wherein each of the first auxiliary and second auxiliary grooves has a greater depth than the main groove.