WO2018086082A1

WO2018086082A1 - Flexible graphite heat sink

Info

Publication number: WO2018086082A1
Application number: PCT/CN2016/105534
Authority: WO
Inventors: 林晓杰
Original assignee: 林晓杰
Priority date: 2016-11-12
Filing date: 2016-11-12
Publication date: 2018-05-17

Abstract

A flexible graphite heat sink, comprising a first metal plate (1) and a second metal plate (2). A surface of the first metal plate (1) is bonded with a first flexible graphite layer by means of heat transfer. A surface of the second metal plate (2) is bonded with a second flexible graphite layer by means of heat transfer. The first metal plate (1) and the second metal plate (2) have, at plate edges, a continuous encapsulation region (5) not covered by the graphite layers. The first flexible graphite layer and the second flexible graphite layer are arranged oppositely and located on inner sides of the first metal plate (1) and the second metal plate (2), respectively. An electric heating wire (6) is placed between the first flexible graphite layer and the second flexible graphite layer. Two electrical connection terminals (7) of the electric heating wire (6) are outside of the outlines of the first metal plate (1) and the second metal plate (2). The continuous encapsulation region (5) of the first metal plate (1) and the second metal plate (2) encapsulates, within a cavity formed by the first metal plate (1) and the second metal plate (2), the first flexible graphite layer, the second flexible graphite layer, the electric heating wire (6), and a heat transfer oil.

Description

Flexible graphite heat sink

Technical field

The invention relates to an electrically heated graphite heat sink, in particular to a flexible graphite heat sink.

Background technique

At present, heating in homes or office places, where there is no central heating, electric heating is commonly used, such as electric oil, using heat-conducting oil as a medium, but the specific heat capacity of the heat-conducting oil is large, resulting in a long warm-up time, and the weight of the electric oil Larger, the outer form is single.

Using the rapid thermal conductivity of graphite, it can be used to make electric heating and heating devices. Flexible graphite has rapid heat conduction, high thermal efficiency and light weight. Compared with electric oil, the electric heater using flexible graphite as the heat conduction medium has the advantages of rapid heating, light weight and can be made into A variety of shapes and other advantages. The Chinese utility model patent specification CN 201976268U discloses a graphite heating plate, which uses a metal foil and a heat insulating material to encapsulate and paste the graphite in the middle, and heats the device to be fixed at the graphite, and the thermostat is connected to the power source to form a graphite heating plate. The form of the rapid heating effect. According to the characteristics of rapid heat transfer of graphite, it can achieve energy-saving effect, and is suitable for wall, floor, bed, mattress, sofa, blanket, felt and so on.

technical problem

However, if the heating device is not in sufficient contact with the heat sink member such as metal foil or graphite, the following problems may occur:

1. The heat of the heating device cannot be dissipated by heat conduction, but is mainly dissipated by heat radiation or heat convection, which lacks a heat dissipation path and affects heat dissipation efficiency;

2, causing local overheating of the heating device and graphite contact, graphite will be oxidized above 500 ° C, if the local superheat temperature is close to 500 ° C, will cause slow oxidation of graphite, thermal conductivity is reduced;

3, causing local overheating of the contact between the heating device and the graphite, which may cause burns to the human body;

4, local heating will cause deformation of the heat sink heat sink, affecting the appearance.

Technical solution

In order to solve the above technical problem, the present invention provides a flexible graphite heat dissipating device, comprising a first metal plate, a second metal plate, and a plate surface of the first metal plate is bonded to the first flexible graphite layer by heat transfer. A plate surface of the second metal plate is heat-transferred to the second flexible graphite layer, and the plate edge of the first metal plate and the second metal plate has a continuous packaging region not covered by the graphite layer, the first flexible graphite The layer and the second flexible graphite layer are respectively disposed opposite to the inner side of the first metal plate and the second metal plate, and the electric heating wire is placed between the first flexible graphite layer and the second flexible graphite layer, and the two electrical connections of the electric heating wire are The end is located outside the outline of the first metal plate and the second metal plate, and the continuous packaging area of the first metal plate and the second metal plate encapsulates the first flexible graphite layer, the second flexible graphite layer, the electric heating wire, and the heat conduction The grease is encapsulated in a cavity formed by the first metal plate and the second metal plate.

Preferably, in the flexible graphite heat sink of the present invention, the size of the first metal plate is equal to the size of the second metal plate, and the area of the first flexible graphite layer and the second flexible graphite layer is smaller than the area of the first metal plate. Its shape is simple and easy to manufacture. Further, the contour edge of the first flexible graphite layer is reduced by 0.2 mm to 50 mm from the edge of the first metal plate, and the reduced size is more suitable for the solder package or the silicone package at the edge of the metal plate.

As a preferred embodiment, the first metal plate and the second metal plate of the flexible graphite heat dissipating device of the present invention may be an iron plate, a steel plate or an aluminum plate, and an alloy plate.

As a preferred embodiment, the electric heating wire of the flexible graphite heat dissipating device of the present invention may be a glass fiber electric heating cable.

Specifically, the flexible graphite heat sink of the present invention is packaged in a solder package or a silicone package.

In order to better prevent leakage, the two connecting ends of the electric heating wire of the flexible graphite heat dissipating device of the present invention have a mica plate between the first metal plate and the second metal plate, and the mica plate functions as electrical insulation.

Beneficial effect

The flexible graphite heat dissipating device provided by the invention is characterized in that the thermal grease is encapsulated in a cavity formed by the first metal plate and the second metal plate, and a part of the space is reserved for filling the gas, and the gas is easily compressed to prevent thermal expansion of the thermal grease. The package is broken, and the volume of the filled air may be ten percent of the volume of the cavity formed by the first metal plate and the second metal plate. The electric heating wire is in direct contact with the flexible graphite (graphite paper), and the flexible graphite (graphite paper) and the thermal grease are used together as a heat transfer and heat dissipation method, and the heat transfer using only the flexible graphite (graphite paper) or simply using the thermal grease is used. Compared with the heat dissipation method, there are at least the following advantages:

First, heat can be transferred by heat conduction, and heat can be transferred by convection. Flexible graphite (graphite paper) has a fast heat transfer rate and a lateral thermal conductivity of 800 to 1500 w/mk. Compared with metal, the flexible graphite layer can rapidly transfer the heat of the heating element, thereby reducing the temperature of the heating element and improving heat transfer. s efficiency. For example, aluminum has a thermal conductivity of 228 w/mk, copper of about 370 w/mk, iron of about 70 w/mk, and carbon steel of about 50 w/mk.

Secondly, the improvement of heat transfer efficiency, plus the addition of thermal grease around the electric heating wire, can more effectively prevent the local temperature of the metal contacted by the electric heating wire from overheating and cause metal deformation, so that the heating temperature of the heating wire is lowered from 350 ° C to At 100 ° C, the local high temperature that can contact the graphite and the metal plate by the electric heating wire causes the graphite to oxidize and the metal plate to be deformed at a high temperature.

Third, the flexible graphite layer has good electrical insulation properties, and the flexible graphite layer is insulated between the heating wire and the metal plate to prevent leakage. The electric heating wire can be selected from the glass fiber heating belt commonly used in the market, but the silicone rubber electric heating belt cannot be used.

Fourth, since the electric heating wire is enclosed in the cavity formed by the first metal plate and the second metal plate, the air can be isolated to avoid the problem of rust failure caused by the humidity of the air.

Fifth, the use of flexible graphite (graphite paper) and thermal grease as a means of heat transfer and heat dissipation, compared with the heat transfer method using only flexible graphite (graphite paper) or simply using thermal grease, the heat transfer efficiency is improved. Compared with the traditional oil heater, the weight of the radiator can be greatly reduced to 13~15kg, which is convenient for transportation, movement and installation, saving Use of raw materials such as thermal grease.

DRAWINGS

Figure 1 is a front view of the flexible graphite heat sink of the present invention

2 is a cross-sectional view of the flexible graphite heat sink of the present invention taken along line A-A

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 1 and FIG. 2, a specific embodiment of the flexible graphite heat dissipating device of the present invention is a planar shape, two pieces of rectangular iron having a length of 80 cm and a width of 50 cm, which are respectively a first metal plate (1) and a second metal plate ( 2), the two metal plates are iron plates, the thermal conductivity is 70w/mk, and the thickness is 4mm. One plate surface of the first metal plate (1) is heat-transferred to the first flexible graphite layer (3), and one plate surface of the second metal plate (2) is heat-transferred to have a second flexibility The graphite layer (4), the thickness of the flexible graphite layer was 1 mm, and the transverse thermal conductivity was measured to be 1200 w/mk. The plate edge of the first metal plate (1) and the second metal plate (2) has a continuous encapsulation region (5) not covered by the graphite layer, that is, the contour edge of the first flexible graphite layer (3) is away from the first metal The edge of the plate (1) is reduced by 10 mm to the inside, leaving a space for the edge of the metal plate, and is encapsulated with a silicone. The first flexible graphite layer (3) and the second flexible graphite layer (4) are respectively placed opposite to the inner side of the first metal plate (1) and the second metal plate (2), and the electric heating wire (6) is electrically heated glass fiber. Line, power 1000w, rated voltage 220V, placed at a pitch of 8cm between the first flexible graphite layer (3) and the second flexible graphite layer (4), two electrical connection ends of the electric heating wire (6) (7) Located outside the outline of the first metal plate (1) and the second metal plate (2), the continuous packaging area (5) of the first metal plate (1) and the second metal plate (2) will be firstly sealed using a silicone package The flexible graphite layer (3), the second flexible graphite layer (4), the electric heating wire (6), and the thermal grease are encapsulated in a cavity formed by the first metal plate (1) and the second metal plate (2).

The flexible graphite heat dissipating device of the present embodiment was measured in a closed 16 square meter room, a rectangular heat sink with a length of 80 cm and a width of 50 cm, inputting 220 v, power of 1000 W, and measuring the temperature of the indoor measuring point with different heating time and different distances. The values are as follows:

加热时间heating time	距离1mDistance 1m	距离2mDistance 2m	距离3mDistance 3m	远方distance
0min0min	24℃24 ° C	24℃24 ° C	24℃24 ° C	23.9℃23.9 ° C
30min30min	24.7℃24.7 ° C	24.5℃24.5 ° C	24.3℃24.3 ° C	23.9℃23.9 ° C
60min60min	25.4℃25.4°C	25.2℃25.2°C	25.3℃25.3 ° C	23.9℃23.9 ° C
120min120min	27.3℃27.3°C	27.1℃27.1°C	26.9℃26.9 ° C	24.1℃24.1 ° C

After heating for 2 hours, the surface temperature of the iron plate was stabilized at 70 ° C, and no high temperature deformation occurred.

Embodiments of the invention

The difference between this embodiment and the above preferred embodiment is that in order to better prevent leakage, heat dissipation in flexible graphite A mica plate is added between the two connection ends of the electric heating wire of the device and the first metal plate (1) and the second metal plate (2), and the mica plate functions to be electrically insulated.

Industrial applicability

The invention can be used industrially for production. However, the present invention is not limited to the above-described contents, and it is within the scope of the present invention to fall within the scope of the present invention without departing from the scope of the present invention.

Claims

A flexible graphite heat dissipating device comprises a first metal plate (1) and a second metal plate (2). One plate surface of the first metal plate (1) is heat-transferred to the first flexible graphite layer (3) a plate surface of the second metal plate (2) is thermally coupled to the second flexible graphite layer (4), and the plate edges of the first metal plate (1) and the second metal plate (2) are a continuous encapsulation region (5) not covered by a graphite layer, the first flexible graphite layer (3) and the second flexible graphite layer (4) are respectively located inside the first metal plate (1) and the second metal plate (2) Placement, the electric heating wire (6) is placed between the first flexible graphite layer (3) and the second flexible graphite layer (4), and the two electrical connection ends (7) of the electric heating wire (6) are located on the first metal plate. (1) and the outline of the second metal plate (2), characterized in that the continuous packaging area (5) of the first metal plate (1) and the second metal plate (2) encapsulates the first flexible graphite in a package manner The layer (3), the second flexible graphite layer (4), the electric heating wire (6), and the thermal grease are encapsulated in a cavity formed by the first metal plate (1) and the second metal plate (2).
The flexible graphite heat sink according to claim 1, wherein the size of the first metal plate (1) is equal to the size of the second metal plate (2), the first flexible graphite layer (3) and the second flexible graphite layer The area of (4) is smaller than the area of the first metal plate (1).
The flexible graphite heat sink according to claim 1 or 2, wherein the contour edge of the first flexible graphite layer (3) is reduced inward by 0.2 mm to 50 mm from the edge of the first metal plate (1).
The flexible graphite heat sink according to claim 1, wherein the first metal plate (1) and the second metal plate (2) are iron plates, steel plates, aluminum plates or alloy plates.
The flexible graphite heat sink according to claim 1, wherein the electric heating wire (4) is a glass fiber electric heating cable.
The flexible graphite heat sink according to claim 1, wherein the package is a solder package or a silicone package.
The flexible graphite heat sink according to claim 1, wherein the heat conductive grease is cutting oil, lubricating oil or high temperature mechanical oil.
The flexible graphite heat dissipating device according to claim 1, wherein the two connecting ends of the electric heating wire (6) and the first metal plate (1) and the second metal plate (2) have mica sheets .