Heat dissipater for a central processing unit

[0002] 1. Field of the Invention

[0003] The present invention relates to a heat dissipater, and more particularly to a heat dissipater that is adapted to be mounted on a CPU (Central Processing Unit) and includes a chamber corresponding to a cooling fan and containing liquid to promote the dissipation of heat.

[0004] 2. Description of Related Art

[0005] The working temperature of CPUs corresponds to the frequency of the CPU. A high frequency causes a high working temperature. However, a high working temperature damages the electrical and electronic elements of the computer that contain the CPU. Consequently, a heat dissipater for a central processing unit is marketed.

[0006] With reference to FIG. 11, a conventional heat dissipater for a central processing unit in accordance with the prior art comprises a plate (60) and multiple fins (62). The plate (60) has a first side adapted to abut a heat source (70), such as a CPU, and a second side having multiple parallel heat dissipating fins (62) extending upward from the second side of the plate (60). A cooling fan (80) is attached to the top of the dissipating fins (62) to promote the dissipation of heat.

[0007] However, new CPUs, such as the Pentium 4 manufactured by Intel, operate at a frequency greater than one giga-hertz so that the conventional heat dissipater needs to be altered to dissipate the heat generated by high-frequency CPUs.

[0008] The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional heat dissipater for a central processing unit.

[0009] The main objective of the present invention is to provide an improved heat dissipater for a CPU capable of dissipating much more heat with a device fundamentally the same size as the conventional device.

[0010] To achieve the main objective, the heat dissipater for a CPU in accordance with the present invention comprises an upper block and a lower block abutting each other. The upper block has a series of fins extending upward from a first side of the upper block and a recess defined in a second side of the upper block. The lower block includes a first side having a recess defined to correspond to the recess in the upper block and forming a closed chamber with the recess in the upper block and a second side adapted to abut the CPU. Volatile liquid fills the close chamber to promote the dissipation of heat by the heat dissipater for a CPU.

[0011] Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.

[0012] FIG. 1 is a perspective view of a heat dissipater for a CPU in accordance with the present invention;

[0013] FIG. 2 is an exploded perspective view of the heat dissipater in FIG. 1;

[0014] FIG. 3 is a cross sectional side plan view of a lower block of the heat dissipater in FIG. 2 along line 3—3;

[0015] FIG. 4ais a cross sectional side plan view of a first embodiment of a series of capillary grooves in the heat dissipater in FIG. 1;

[0016] FIG. 4bis a cross sectional side plan view of a second embodiment of a series of capillary grooves of the heat dissipater in FIG. 1;

[0017] FIG. 4cis a cross sectional side plan view of a third embodiment of a series of capillary grooves of the heat dissipater in FIG. 1;

[0018] FIG. 5 is a perspective view of a second embodiment of a heat dissipater for a CPU in accordance with the present invention;

[0019] FIG. 6 is an exploded perspective view of the heat dissipater in FIG. 5;

[0020] FIG. 7 is a cross sectional side plan view of the heat dissipater in FIG. 5 along line 7—7;

[0021] FIG. 8 is a partially exploded view of the heat dissipater in FIG. 5 showing a series of capillary grooves in the second embodiment of the present invention;

[0022] FIG. 9 is a perspective view of a third embodiment of a heat dissipater for a CPU in accordance with the present invention;

[0023] FIG. 10 a schematic side view of the heat dissipater in accordance with the pressure invention showing the air flow and dissipation of heat; and

[0024] FIG. 11 is an exploded perspective view of a conventional heat dissipater for a CPU in accordance with the prior art.

[0025] With reference to the drawings and initially to FIGS. 1, 2 and 3, a heat dissipater for a CPU in accordance with the present invention comprises an upper block (10), a lower block (20) abutting each other to form a closed chamber (30) between the two blocks (10, 20). The lower block (20) is securely attached to the bottom of the upper block (10) by a method selected from a group consisting of welding, ultrasonic wave welding or gluing. The methods for manufacturing the upper block (10) and the lower block (20) are die casting or semi-solid injection molding.

[0026] The upper block (10) comprises a series of fins (16) extending upward from a first side (14) of the upper block (10) and a recess (12) defined in a second side of the upper block (10). The upper block (10) is made of a good thermal conductive material, such as copper, magnesium, aluminum or an alloy of the above materials and the fins (16) integrally extend from the upper block (10). The series of fins (16) are parallel to one another and the topmost of the fins (16) is adapted to mount a cooling fan (40) on the upper block (10). A series of parallel capillary grooves (120) is defined in a periphery of the recess (12) of the upper block (10).

[0027] The lower block (20) is made of a good thermal conductive material, such as copper, magnesium, aluminum or an alloy of the above materials. The lower block (20) comprises a recess (22) defined in a first side of the lower block (20) and corresponding to the recess (12) in the upper block (10). The two recesses (12, 22) of the two blocks (10, 20) define the chamber (30) when the two blocks (10, 20) are securely attached to each other. A series of parallel capillary grooves (220) are defined in a periphery of the recess (22) of the lower block (20). Each capillary groove (220) in the lower block (20) aligns and communicates with a corresponding one of the capillary grooves (120) in the upper block (10). An inlet (26) is defined in the lower block (20) and communicates with the chamber (30) to allow the chamber (30) to be partially filled with liquid. The liquid is volatile, such as pure water, methanol, toluene, coolant or the like.

[0028] The closed chamber (30) is drawn to be vacuum via the inlet (26). Then volatile liquid, such as pure water, methanol, toluene, coolant or the like, is charged into the vacuum close chamber (30). The inlet (26) is sealed as the adequate liquid is charged into. Creating a vacuum in the chamber (30) is to prevent the non-condensable gas and contamination in the air from staying in the chamber (30). It will have an adverse influence on the performance of dissipating heat. The other reason to vacuum is that the operating temperature is often lower than the vaporized temperature at atmospheric pressure. The volume of volatile liquid depends on the operating temperature and dissipating heat flux that you intend.

[0029] Heat from heat source, such as CPU, thermally conducts through the lower block (20) then, conducts through the volatile liquid filled evaporator capillaries thereby heating the volatile liquid until it vaporizes at the designed operating temperature then, the high temperature (thus high pressure) vapor flow adiabatically (without heat loss or gain) toward the far end which is in lower temperature (thus low pressure). Then the heated vapor condenses and gives up its latent heat of vaporization due to fanned air current guided by fins (16). The condensed volatile liquid returns to the evaporator through the capillaries of the upper and lower blocks (10, 20).

[0030] The cross sectional shape of the capillary groove (120, 220) can be several types. With reference to FIG. 4-A, the cross sectional shape of the capillary groove (120X,220X) is rectangular. With reference to FIG. 4-B, the cross sectional shape of the capillary groove (120Y/220Y) is trapezoid. With reference to FIG. 4-C, the cross sectional shape of the capillary groove (120Z/220Z) is triangle.

[0031] With reference to FIGS. 5-7, a second embodiment of the heat dissipater for a CPU in accordance with the present invention comprises an upper block (10a), a lower block (20a) and a fan (40a). The upper block (10a) includes multiple fins (16a) extending upwardly from the first side (14a) of the upper block (10a). Each fin (16a) is directed toward the center of the upper block (10a) and has a cutout (not numbered) near the center of the upper block (10a) to form a receiving space (160a) to accommodate the cooling fan (40a) in the upper block (10a).

[0032] With reference to FIGS. 6 and 8, the recesses (12a, 22a) in the upper and lower blocks (10a, 20a) are respectively divided into four isosceles triangles each having an apex at the center of the upper and the lower blocks (10a, 20a). The capillary grooves (120a, 220a) of opposite triangles are parallel to each other, and the capillary grooves (120a, 220a) of adjacent triangles communicates with each other. The capillary grooves (120a) in the upper block (10a) align with the corresponding capillary grooves (220a) in the lower block (20a).

[0033] With reference to FIG. 9, a third embodiment of the heat dissipater for a CPU in accordance with the present invention has an inlet (15b) formed on the upper block (10b) that communicates with the chamber (30) defined by the recesses (12, 13) of the upper block (10b) and the lower block (20b).

[0034] With reference to FIG. 10, in use the bottom of the lower block (20) the heat dissipater abuts a heat source (A), such as a CPU. The vapor-liquid balance in the chamber (30) changes when the CPU operates and raises the temperature. The liquid in the chamber (30) is vaporized due to the increased temperature caused by the CPU, and the vapor (B) from the liquid completely fills the chamber (30). The liquid vapor (B) condenses in the capillary grooves (120) in the upper block (10) because the cooling fan (40) generates an air current (D) that blows on the first side (14) of the upper block (10) to reduce the temperature of the upper block (10) and the lower block (20). The condensed vapor (C) flows into the recess (22) in the lower block (20) along the capillary grooves (120, 220) in the upper and lower blocks (10, 20). The liquid is vaporized again after flowing into the recess (22) in the lower block (20). By such an arrangement and vapor-liquid circulation, the temperature of the CPU is effectively reduced by the heat dissipater in accordance with the present invention when the CPU is operating.

[0035] The liquid in the chamber (30) absorbs the heat generated by a working CPU to reduce the temperature of the working CPU. Consequently, the heat dissipation of the heat dissipater in accordance with the present invention is more effective than that of the conventional heat dissipater. A lower working temperature effectively lengthens the useful life of the electrical and electronic elements.

[0036] Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.