CN104241513A - High-power LED multi-hole phase-changing heat sink structure - Google Patents

Abstract

A high-power LED porous phase-change heat sink structure, including a radiator cavity with several radiator fins on the top surface, a metal porous structure is sintered in the radiator cavity, and the pores of the metal porous structure are filled with phase-change Material; the bottom surface of the inner cavity of the radiator is provided with an LED electronic chip, and the melting point of the phase change material is lower than the normal working temperature of the LED electronic chip. The invention can improve the response rate of the phase change latent heat storage, and reduce the weight and cost of the LED heat dissipation structure, and when the LED is working, part of the heat emitted by the chip is dissipated in the form of natural convection, and most of it is absorbed by the latent heat absorbed during the melting process of the phase change material. At the same time, the temperature of the LED chip is controlled by the melting point of the phase change material, and the heat dissipation performance is improved. The structure of the invention has the advantages of simple structure, light weight, small volume, good adjustability, good heat dissipation effect, long service life, no external energy consumption and no environmental pollution.

Description

A High Power LED Porous Phase Change Heat Sink Structure

technical field

The invention relates to the lighting field, in particular to a high-power LED porous phase-change heat sink structure.

technical background

In recent years, with the shortage of energy supply, semiconductor light-emitting diode (Light Emitting Diode) lighting has received extensive attention from all over the world. Because of its advantages of high luminous efficiency, long life, safety and environmental protection, it is called the fourth generation lighting. Light source or green light source, LED lighting has been widely used in special-purpose lighting systems such as mobile phone flashlights, display backlights, signs and signal lights, and miner's lamps. In view of the advantages of LEDs, it will be used in household lighting, automotive headlights, stage lighting and architectural The field of high-power lighting such as construction site lighting has shown great potential and prospects. However, although the brightness of high-power LED lights is higher, the heat generated inside will also increase significantly, which will increase the temperature of the semiconductor PN junction, reduce the luminous efficiency, and change the peak wavelength of the LED, thus causing light decay. Seriously reduce the service life of LED. Therefore, the temperature of the PN junction of the LED needs to be controlled below a given safe temperature (such as 125°C). Traditional incandescent light dissipates heat in the form of infrared radiation, while LED emits light by exciting electrons and causing electrons to jump in energy levels. The spectrum does not contain infrared parts, and the heat generated cannot be dissipated through radiation. 80% of the electrical energy is converted into heat and lost to the external environment. Therefore, the heat dissipation and effective temperature control of high-power LED lighting have become one of the bottlenecks in the application of high-power LEDs.

The existing cooling technology for high-power LED lighting mainly adopts a heat sink package structure, which transfers the heat generated by the LED chip to the lamp housing through heat conduction, and then takes it away by natural convection for cooling. Patent CN2735548 discloses a cooling box packaged with silicon oil and a disturbance system is designed in the box to reduce the temperature of the LED chip. The disadvantage is that the disturbance system requires additional energy consumption and has poor reliability. Patent CN1828956A discloses a high-power LED heat-dissipating package. Its principle is to use the heat pipe of the phase change boiling heat transfer method to dissipate heat to the environment. The terminal ambient temperature has a great influence and is not suitable for LED devices with a light array structure. Patent CN101315927A discloses a high-power LED phase-change heat sink structure. The principle is to use the liquid-gas phase change of the working medium to realize the thermal isothermal effect of the heat sink body to reduce the temperature of the LED chip. The disadvantage is that the heat transfer capacity depends on the phase change. Variable material encapsulation. Patent WO2009110987A1 discloses a heat storage system using phase-change materials for LED lamps. Its structure is to replace the traditional metal heat sink with a heat sink with a cavity. When the material melts, it absorbs heat and stores energy to reduce the temperature of the LED chip. The disadvantage is that the thermal conductivity of the phase change material is low and the heat transfer capacity is limited. Patent US20090322229A1 discloses a new type of LED lighting device. Its principle is to reduce the temperature of the LED chip by transferring the heat of the LED chip to the phase-change material buried in the ground through a heat pipe. The disadvantage is that the cost of this structure is high. Occasions are limited, not conducive to promotion.

Contents of the invention

The object of the present invention is to provide a high-power LED porous phase-change heat sink structure, which has a good heat dissipation effect, reduces the dependence of the LED packaging temperature on the heat dissipation method, and prolongs the heat dissipation time.

In order to achieve the above object, the technical solution adopted by the present invention is: a radiator inner chamber with several radiator fins arranged on the top surface, a metal porous structure is sintered in the radiator inner chamber, and the pores of the metal porous structure are filled with phase A change material; the bottom surface of the inner cavity of the radiator is provided with an LED electronic chip, and the melting point of the phase change material is lower than the normal working temperature of the LED electronic chip.

Interference chutes are processed on each radiator fin, and the total width of the interference chutes on each radiator fin is less than or equal to 20-30% of the total width of each radiator fin.

Along the height direction of the radiator fins, the thickness of each radiator fin gradually increases, and the part of the radiator fins in contact with the top surface of the radiator inner cavity is the thickest.

The metal porous structure is a metal foam porous structure or a metal fiber mat porous structure.

The porosity of the metal porous structure ranges from 30% to 99%.

The volume filling rate of the phase change material in the metal porous structure is less than 95%.

The phase change material is sodium citrate, sodium phosphate, nitrate or paraffin.

An expansion board is provided between the bottom surface of the inner cavity of the radiator and the LED electronic chip, and a sealing end cover for sealing the inner cavity of the radiator is arranged on the side of the inner cavity of the radiator.

The plurality of fins of the radiator are connected to the top surface of the inner cavity of the radiator by welding or machining, the expansion board and the LED electronic chip, and the bottom surface of the inner cavity of the radiator and the expansion board Connected by welding or thermal grease bonding.

When the LED electronic chip stops working, the phase change material releases heat and solidifies; when the LED works normally, the phase change material absorbs heat and melts.

Compared with prior art, the beneficial effect of the present invention is:

1. The present invention is provided with several radiator fins on the top surface of the radiator cavity, therefore, a part of the heat generated when the LED electronic chip is working can be transferred to the surface of the radiator cavity, and with the help of the radiator fins At the same time, there is a metal porous structure sintered in the inner cavity of the radiator, and phase change materials are encapsulated in the pores of the metal porous structure. Therefore, most of the heat generated by the LED electronic chip is absorbed by the phase change material. Storage of latent heat absorbed during melting. At the same time, the temperature of the LED chip is controlled by the melting point of the phase change material. After the LED stops working, the phase change material releases heat and solidifies again, and the filling amount of the phase change material can be adjusted according to the power and working time, which improves the heat dissipation performance. The invention can also use the melting point of the phase change material to effectively control the temperature of the LED, so that the dependence of the LED temperature on the heat dissipation method is reduced, and the heat dissipation time is prolonged. Therefore, the heat dissipation effect of the invention is good and can be applied to high-power LED.

2. The present invention utilizes the advantages of large solid-liquid phase change latent heat, small volume expansion and easy control of phase change materials, and a metal porous structure is sintered in the heat dissipation inner cavity to improve the effective thermal conductivity of the phase change material, thereby increasing the latent heat of phase change The stored response rate makes the melting process of the phase change material more uniform, more conducive to the temperature control of the phase change, and reduces the weight and cost of the LED heat dissipation structure. Therefore, the present invention has simple structure, light weight, small volume, and adjustable Good, long life, and no external energy consumption and no environmental pollution and other advantages.

Further, the phase change material used in the present invention is cheap, has small change in phase change volume, and is easy for industrial application.

Description of drawings

Fig. 1 is the schematic diagram of high-power LED porous phase change heat sink structure of the present invention;

Fig. 2 is A-A sectional view among Fig. 1;

Fig. 3 is a partial top view schematic diagram of Fig. 1;

Fig. 4 is a comparison diagram of the temperature control effect of an embodiment of the structure of the present invention under three experimental conditions; wherein, h1 is the melting zone 1, and h2 is the melting zone 2.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the present invention includes a radiator cavity 2 with a plurality of radiator fins 1 on the top surface, and a metal porous structure 3 with a porosity ranging from 30% to 99% is sintered in the radiator cavity 2. The porous structure 3 is a metal foam porous structure or a metal fiber felt porous structure prepared by high thermal conductivity metal materials such as aluminum or copper; the pores of the metal porous structure 3 are filled with phase change materials 4, and the metal porous structure 3 can improve the performance of phase change materials. The effective thermal conductivity coefficient of 4, thereby improving the response rate of phase change latent heat storage; the volume filling rate of phase change material 4 in metal porous structure 3 is less than 95%, in order to consider the volume expansion of phase change material after melting; radiator cavity 2 An expansion board 5 made of aluminum or copper is provided on the bottom surface of the base. The bottom of the expansion board 5 is used to combine with the LED electronic chip 6 , and the melting point of the phase change material 4 is lower than the normal operating temperature of the LED electronic chip 6 . These phase change materials 4 can be selected from sodium citrate, sodium phosphate, nitrate or paraffin, but not limited thereto.

The side of the inner cavity of the radiator 2 is provided with a sealing end cap 7 for sealing the inner cavity of the radiator 2; the sealing end cap 7 encapsulates the phase change material 4 in the inner cavity of the radiator 2 by welding, bolting or cementing, filling For phase change materials, directly open the sealing end cap 7, and fill the phase change material 4 in the molten state in the pores of the metal porous structure; wherein between the expansion board 5 and the LED electronic chip 6, the bottom surface of the radiator cavity 2 and the The expansion boards 5 are all connected by welding or heat-conducting silicone grease bonding, and the LED electronic chip 6 adopts a single LED package, multiple LED packages or an LED lamp array (circular array or rectangular array).

As shown in accompanying drawing 2 and Fig. 3, some radiator fins 1 on the top of the radiator cavity 2 in the present invention can increase the heat exchange area, and these radiator fins 1 and the top of the radiator cavity 2 are welded or machined. connected by way of processing; each radiator fin 1 is processed with some interference flow grooves, and the total width of several winding chutes on each radiator fin 1 is less than or equal to the total width of each radiator fin 1 20-30%. Along the height direction of the radiator fin 1, the thickness of each radiator fin 1 gradually increases, and the part of the radiator fin 1 in contact with the top surface of the radiator cavity 2 is the thickest (that is, the radiator fin The root of the chip is thicker and gradually becomes thinner along the height direction), the inclination angle of the radiator fin 1 and the width of the spoiler groove are determined by the power of the LED, but the total width of the spoiler groove does not exceed 20-20% of the total width of the fin. 30%, which can improve the efficiency of natural convection. .

A metal porous structure 3 is sintered in the inner cavity of the radiator 2 to increase the effective thermal conductivity of the phase change material 4 , thereby increasing the response rate of phase change latent heat storage. When the LED is working, part of the heat emitted by the chip is taken away by the convective heat transfer of the fin 1, and most of it is stored by the phase change material 4. After the LED stops working, the phase change material 4 releases heat and re-solidifies, and the heat will be released according to the power and working time. Adjust the filling amount of the phase change material 4 . The bottom of the heat sink is bonded with a copper or aluminum expansion board 5 by welding or thermal grease, and the other side of the expansion board 5 is bonded with a single LED package 6, multiple LED packages or LED lamps by welding or thermal grease. array (circular array or rectangular array).

Fig. 4 is a comparison diagram of the temperature control effect of an embodiment of the structure of the present invention under three experimental conditions, wherein the metal porous structure 3 is copper foam (porosity 0.98, 5PPI), and the phase change material 4 is paraffin. There are 3 curves in the figure, one is the 6-junction thermal resistance curve of the LED package without paraffin, and the other two are the paraffin wax melting points of 52-54°C (melting zone 1) and 60-62°C ( Thermal resistance curve in melting zone 2). As shown in Figure 4, the melting zone of the two cases containing paraffin corresponds to the normal working range of the LED electronic chip. When the LED electronic chip stops working, the paraffin wax stored in the metal porous structure just completely melts, exactly corresponding to the normal working range of the LED electronic chip in Figure 4. At the end of the melting zone, the heat stored in the paraffin begins to be released gradually, and the paraffin re-solidifies, thus forming a cycle of use. As shown in Figure 4, the thermal resistance under the condition of paraffin wax is 25% to 30% smaller than that without paraffin wax, and the improvement effect of the temperature control effect is quite obvious.

Claims (10)

1. A high-power LED porous phase-change heat sink structure, characterized in that: the top surface is provided with a radiator cavity (2) with several radiator fins (1), and the radiator cavity (2) is sintered There is a metal porous structure (3), the pores of the metal porous structure (3) are filled with a phase change material (4); the bottom surface of the inner cavity of the radiator (2) is provided with an LED electronic chip (6), and the phase change material (4 ) has a melting point lower than the normal operating temperature of the LED electronic chip (6). 2. The high-power LED porous phase-change heat sink structure according to claim 1, characterized in that: each radiator fin (1) is processed with several interference flow grooves, and each radiator fin (1) If the total width of the interference chute is less than or equal to 20-30% of the total width of each radiator fin (1). 3. The high-power LED porous phase-change heat sink structure according to claim 1 or 2, characterized in that: along the height direction of the radiator fins (1), the thickness of each radiator fin (1) gradually increases Large, and the part where the radiator fins (1) contact with the top surface of the radiator inner cavity (2) is the thickest. 4. The high-power LED porous phase-change heat sink structure according to claim 1 or 2, characterized in that: the metal porous structure (3) is a metal foam porous structure or a metal fiber mat porous structure. 5. The high-power LED porous phase-change heat sink structure according to claim 1, characterized in that: the porosity of the metal porous structure (3) ranges from 30% to 99%. 6. The high-power LED porous phase change heat sink structure according to claim 1 or 5, characterized in that: the volume filling rate of the phase change material (4) in the metal porous structure (3) is less than 95%. 7. The high-power LED porous phase-change heat sink structure according to claim 1, characterized in that: the phase-change material (4) is sodium citrate, sodium phosphate, nitrate or paraffin. 8. The high-power LED porous phase-change heat sink structure according to claim 1, characterized in that: an expansion board (5 ), the side of the inner cavity of the radiator (2) is provided with a sealing end cover (7) for sealing the inner cavity of the radiator (2). 9. The high-power LED porous phase-change heat sink structure according to claim 8, characterized in that: the plurality of radiator fins (1) and the top surface of the radiator cavity (2) are welded Or machined connection, between the expansion board (5) and the LED electronic chip (6), between the bottom surface of the radiator inner cavity (2) and the expansion board (5) are all welded or bonded with heat-conducting silicone grease connect. 10. The high-power LED porous phase-change heat sink structure according to claim 1, characterized in that: when the LED electronic chip (6) stops working, the phase-change material (4) releases heat and solidifies; , the phase change material (4) absorbs heat and melts.