KR102273886B1 - Vacuum adiabatic body and refrigerator - Google Patents

Abstract

A vacuum insulator according to an aspect of the present invention includes a first plate member; a second plate member; a sealing part sealing the first plate member and the second plate member to provide a third space that is a space in a vacuum state; a supporting unit for maintaining the third space; a heat resistance unit for reducing an amount of heat transfer between the first plate member and the second plate member; and an exhaust port for discharging the gas of the third space, and the heat resistance unit includes a conductive resistance sheet connected to at least one of the plate members and capable of resisting heat conduction flowing along the wall of the third space. The conductive resistance sheet includes a seating portion for seating on the plate member and a curved portion at least partially recessed into the third space, and the seating portion includes a coupling portion for fixing the conductive resistance sheet to the plate member. The curved portion includes a first curved portion that is depressed toward the third space and a second curved portion that extends from the first curved portion and surrounds the edge of the plate member.

Description

Vacuum insulator and refrigerator {Vacuum adiabatic body and refrigerator}

The present invention relates to a vacuum insulator and a refrigerator.

A vacuum insulator is an article that suppresses heat transfer by maintaining a vacuum inside the body. Since the vacuum insulator can reduce heat transfer by convection and conduction, it is being applied to a heating device and a refrigeration device. On the other hand, although the insulation method applied to the conventional refrigerator differs depending on refrigeration and freezing, it was a general method to provide a foamed polyurethane insulation wall having a thickness of about 30 cm or more. However, there is a problem in that the internal volume of the refrigerator is reduced by this.

There is an attempt to apply a vacuum insulator to the refrigerator in order to increase the internal volume of the refrigerator.

First, there is the applicant's registered patent 10-0343719 (cited document 1). According to the registered patent, a vacuum insulation panel is manufactured, the vacuum insulation panel is built into the wall of the refrigerator, and the outside of the vacuum insulation panel is finished with a separate molded product made of Styrofoam. According to the above method, foaming is not required, and the effect of improving thermal insulation performance can be obtained. This method has problems in that the cost increases and the manufacturing method becomes complicated. As another example, Laid-Open Patent Publication 10-2015-0012712 (Citation Document 2) provides a wall with a vacuum insulation material and in addition, it is presented in a technique for providing an insulation wall with a foam filler. This method also has problems in that the cost increases and the manufacturing method is complicated.

As another example, there was an attempt to manufacture the wall of the refrigerator as a single product, a vacuum insulator. For example, US Patent Publication No. US2040226956A1 (Citation 3) discloses providing an insulating structure of a refrigerator in a vacuum state. However, it is difficult to obtain a practical level of insulation effect by providing the wall of the refrigerator in a sufficient vacuum state. In detail, it is difficult to prevent the heat transfer phenomenon between the contact part of the outer case and the inner case having different temperatures, it is difficult to maintain a stable vacuum state, and it is difficult to prevent deformation of the case due to the negative pressure of the vacuum state, etc. There is a problem of Due to these problems, the technology of Citation 3 is also limited to cryogenic refrigeration equipment, and it does not provide a level of technology that can be applied at home.

Registered Patent 10-0343719 7 of Patent Publication 10-2015-0012712 US Patent Publication No. US2040226956A1

The present invention is proposed in the background described above, obtains a sufficient thermal insulation effect by vacuum, and proposes a vacuum insulator and a refrigerator that can be commercially applied.

In order to solve the above problems, the vacuum insulator according to an aspect of the present invention includes a first plate member; a second plate member; a sealing part sealing the first plate member and the second plate member to provide a third space that is a space in a vacuum state; a supporting unit for maintaining the third space; a heat resistance unit for reducing an amount of heat transfer between the first plate member and the second plate member; and an exhaust port for discharging the gas of the third space, and the heat resistance unit includes a conductive resistance sheet connected to at least one of the plate members and capable of resisting heat conduction flowing along the wall of the third space. The conductive resistance sheet includes a seating portion for seating on the plate member and a curved portion at least partially recessed into the third space, and the seating portion includes a coupling portion for fixing the conductive resistance sheet to the plate member. The curved portion includes a first curved portion that is depressed toward the third space and a second curved portion that extends from the first curved portion and surrounds the edge of the plate member.

In order to solve the above problems, the vacuum insulator according to another aspect of the present invention includes a first plate member; a second plate member; a sealing part sealing the first plate member and the second plate member to provide a third space that is a space in a vacuum state; a supporting unit for maintaining the third space; a heat resistance unit for reducing an amount of heat transfer between the first plate member and the second plate member; and an exhaust port for discharging the gas of the third space, and the heat resistance unit includes a conductive resistance sheet connected to at least one of the plate members and capable of resisting heat conduction flowing along the wall of the third space. The conductive resistance sheet includes a curved portion formed by being depressed into the third space due to a pressure difference, and a seating portion provided at both ends of the curved portion and seated on the plate member.

In order to solve the above problems, a refrigerator according to an aspect of the present invention includes a main body; and a door, and in order to supply a refrigerant to the main body, a compressor; condenser; inflator; and an evaporator, wherein at least one of the main body and the door includes a vacuum insulator, and the vacuum insulator includes: a first plate member; a second plate member; a sealing part sealing the first plate member and the second plate member to provide a vacuum space part; a supporting unit for maintaining the vacuum space; heat resistance unit; and an exhaust port for discharging the gas of the vacuum space, wherein the heat resistance unit includes a conductive resistance sheet connected to at least one of the plate members and capable of resisting heat conduction flowing along the wall of the third space, , The conductive resistance sheet includes at least a portion of a curved portion recessed into the third space and a seating portion that is seated on the plate member.

The vacuum insulation effect according to the present invention can be obtained.

1 is a perspective view of a refrigerator according to an embodiment.
2 is a diagram schematically illustrating a vacuum insulator used for a main body and a door of a refrigerator.
3 is a view showing various embodiments of the internal configuration of the vacuum space part.
4 is a view showing various embodiments of a conductive resistance sheet and its peripheral portion.
5 is a cross-sectional view of the conductive resistance sheet and the first plate member.
6 is a graph for explaining the design criteria of the conductive resistance sheet.
7 is a view showing the action of atmospheric pressure on the conductive resistance sheet.
8 is a view for explaining the relationship between atmospheric pressure and the tension acting on the conductive resistance sheet.
9 is a graph showing a change in thermal insulation performance and a change in gas conductivity according to vacuum pressure by applying a simulation.
10 is a graph for observing the process of evacuating the inside of the vacuum insulator with time and pressure when the supporting unit is used.
11 is a graph comparing vacuum pressure and gas conductivity.

Hereinafter, specific embodiments of the present invention are proposed with reference to the drawings. However, the spirit of the present invention is not limited to the embodiments presented below, and those skilled in the art who understand the spirit of the present invention may add, change, delete, and add components to other embodiments included within the scope of the same spirit. It will be easy to suggest by, etc., this will also be included within the scope of the present invention.

In the drawings presented below, different from the actual article, exaggerated, simple or detailed parts may be omitted, but this is for the convenience of understanding the technical idea of the present invention, and the size, structure and shape presented in the drawings should not be construed as limited.

In the following description, vacuum pressure means any pressure state lower than atmospheric pressure. And, the expression that A has a higher degree of vacuum than B means that the vacuum pressure of A is lower than that of B.

1 is a perspective view of a refrigerator according to an embodiment.

Referring to FIG. 1 , a refrigerator 1 includes a main body 2 provided with a cavity 9 for storing stored items, and a door 3 provided to open and close the main body 2 . The door 3 may be rotatably arranged or slidably arranged to open and close the cavity 9 . The cavity 9 may provide at least one of a refrigerating compartment and a freezing compartment.

A component constituting a refrigeration cycle for supplying cold air to the cavity is provided. Specifically, a compressor 4 for compressing the refrigerant, a condenser 5 for condensing the compressed refrigerant, an expander 6 for expanding the condensed refrigerant, and an evaporator 7 for evaporating the expanded refrigerant to take heat ) is included. As a typical structure, a fan may be installed at a position adjacent to the evaporator 7 , and the fluid blown from the fan may be blown into the cavity 9 after passing through the evaporator 7 . By adjusting the amount of air blown by the fan and the blowing direction, adjusting the amount of circulating refrigerant, or adjusting the compression ratio of the compressor, the refrigeration load may be adjusted, thereby controlling the refrigerating space or the freezing space.

2 is a view schematically showing a vacuum insulator used for the main body and door of the refrigerator. The vacuum insulator on the body side is shown with the upper and side walls removed, and the vacuum insulator on the door side is part of the front wall. is a diagram of the removed state. In addition, the cross-section of the portion where the conductive resistance sheets 60 and 63 are provided is schematically shown to facilitate understanding.

Referring to FIG. 2 , the vacuum insulator includes a first plate member 10 providing a wall of a low temperature space, a second plate member 20 providing a wall of a high temperature space, and the first plate member 10 ) and a vacuum space portion 50 defined as a gap between the second plate member 20 is included. Conduction resistance sheets 60 and 63 for preventing heat conduction between the first and second plate members 10 and 20 are included. A sealing part 61 for sealing the first plate member 10 and the second plate member 20 is provided in order to seal the vacuum space part 50 . When the vacuum insulator is applied to a refrigerator or a refrigerator, the first plate member 10 may be referred to as an inner case, and the second plate member 20 may be referred to as an outer case. A machine room 8 is placed on the lower rear side of the vacuum insulator on the main body side, in which parts providing a refrigeration cycle are accommodated, and on either side of the vacuum insulator, air in the vacuum space part 50 is exhausted to create a vacuum state. An exhaust port 40 is provided for In addition, a conduit 64 passing through the vacuum space 50 may be further installed for the installation of defrost water and electric lines.

The first plate member 10 may define at least a part of a wall for a first space provided on the side of the first plate member. The second plate member 20 may define at least a part of a wall for a second space provided on the side of the second plate member. The first space and the second space may be defined as spaces having different temperatures. Here, the wall for each space may function not only as a wall in direct contact with the space but also as a wall not in contact with the space. For example, the vacuum insulator of the embodiment may be applied even to an article having a separate wall in contact with each space.

Factors causing the loss of thermal insulation effect of the vacuum insulator include heat conduction between the first plate member 10 and the second plate member 20 and heat radiation between the first plate member 10 and the second plate member 20, and gas conduction of the vacuum space part 50 .

Hereinafter, a heat resistance unit provided to reduce adiabatic loss in relation to the factor of heat transfer will be described. On the other hand, the vacuum insulator and the refrigerator of the embodiment do not exclude further having another heat insulating means on at least one side of the vacuum insulator. Therefore, it may further have a heat insulating means using foam or the like on the other surface.

3 is a view showing various embodiments of the internal configuration of the vacuum space part.

First, referring to FIG. 3A , the vacuum space unit 50 is provided as a third space at a pressure different from that of the first space and the second space, preferably in a vacuum state, so that insulation loss can be reduced. The third space may be provided at a temperature corresponding to a temperature between the temperature of the first space and the temperature of the second space. Since the third space is provided as a space in a vacuum state, the first plate member 10 and the second plate member 20 contract in a direction approaching each other by a force equal to the pressure difference in each space. The vacuum space 50 may be deformed in a smaller direction because of the In this case, an increase in the amount of radiation transmission due to the contraction of the vacuum space portion and an increase in the amount of conduction transmission due to the contact of the plate members 10 and 20 may cause thermal insulation loss.

A supporting unit 30 may be provided to reduce deformation of the vacuum space 50 . The supporting unit 30 includes a bar 31 . The bar 31 may extend in a direction substantially perpendicular to the plate member to support a gap between the first plate member and the second plate member. A support plate 35 may be additionally provided at at least one end of the bar 31 . The support plate 35 may connect at least two or more bars 31 and extend in a horizontal direction with respect to the first and second plate members 10 and 20 . The support plate may be provided in a plate shape, and may be provided in a grid shape so that an area in contact with the first and second plate members 10 and 20 is reduced to reduce heat transfer. The bar 31 and the support plate may be fixed in at least one part and inserted together between the first and second plate members 10 and 20 . The support plate 35 may contact at least one of the first and second plate members 10 and 20 to prevent deformation of the first and second plate members 10 and 20 . In addition, based on the extension direction of the bar 31 , the total cross-sectional area of the support plate 35 is greater than the total cross-sectional area of the bar 31 , so that the heat transferred through the bar 31 is It may be diffused through the support plate 35 .

As a material of the supporting unit 30, in order to obtain high compressive strength, low outgassing and water absorption, low thermal conductivity, high compressive strength at high temperature, and excellent workability, PC, glass fiber PC, low outgassing PC , PPS, and a resin selected from LCP may be used.

A radiation resistance sheet 32 for reducing thermal radiation between the first and second plate members 10 and 20 through the vacuum space portion 50 will be described. The first and second plate members 10 and 20 may be made of a stainless material capable of preventing corrosion and providing sufficient strength. Since the stainless material has a relatively high emissivity of 0.16, a lot of radiant heat transfer may occur. In addition, the emissivity of the supporting unit made of resin is lower than that of the plate member, and since it is not entirely provided on the inner surfaces of the first and second plate members 10 and 20, it does not significantly affect radiant heat. Therefore, the radiation resistance sheet is provided in a plate shape across most of the area of the vacuum space part 50 in order to focus on the reduction of radiant heat transfer between the first plate member 10 and the second plate member 20 . can be As a material of the radiation-resisting sheet 32, an article having a low emissivity is preferable, and in an embodiment, an aluminum thin plate having an emissivity of 0.02 may be preferably used. In addition, since it is not possible to obtain a sufficient radiation heat shielding effect with one sheet of radiation resistance sheet, at least two sheets of radiation resistance sheet 32 may be provided at a predetermined interval so as not to contact each other. In addition, at least one radiation resistance sheet may be provided in a state in contact with the inner surfaces of the first and second plate members 10 and 20 .

Referring to FIG. 3B , the spacing between the plate members may be maintained by the supporting unit 30 , and the porous material 33 may be filled in the vacuum space 50 . The porous material 33 may have a higher emissivity than stainless steel, which is a material of the first and second plate members 10 and 20, but since the vacuum space is filled, the resistance efficiency of radiant heat transfer is high.

In the case of this embodiment, there is an effect that the vacuum insulator can be manufactured without the radiation resistance sheet 32 .

Referring to FIG. 3C , the supporting unit 30 for maintaining the vacuum space part 50 is not provided. Instead of this, the porous material 33 was provided in a state wrapped in the film 34 . At this time, the porous material 33 may be provided in a compressed state so as to maintain a gap between the vacuum space portions. The film 34 may be provided in a state in which a hole is punched, for example, as a PE material.

In the case of this embodiment, the vacuum insulator can be manufactured without the supporting unit 30 . In other words, the porous material 33 may perform the function of the radiation resistance sheet 32 and the function of the supporting unit 30 together.

4 is a view showing various embodiments of a conductive resistance sheet and its peripheral portion. Although the structure of each conductive resistance sheet is simply illustrated in FIG. 2 , it will be understood in more detail through this drawing.

First, the conductive resistance sheet shown in FIG. 4A can be preferably applied to the vacuum insulator on the main body side. In detail, the second plate member 20 and the first plate member 10 must be sealed to maintain the vacuum inside the vacuum insulator. In this case, since the two plate members have different temperatures, heat transfer may occur between them. A conductive resistance sheet 60 is provided to prevent heat conduction between two plate members of different types.

The conductive resistance sheet 60 may be provided as a sealing portion 61 that is sealed at both ends to define at least a part of a wall for the third space and maintain a vacuum state. The conductive resistance sheet 60 is provided as a micrometer thin plate in order to reduce the amount of heat conduction flowing along the wall of the third space. The sealing part 610 may be provided as a welding part. That is, the conductive resistance sheet 60 and the plate members 10 and 20 may be fused to each other. In order to induce a fusion action between each other, the conductive resistance sheet 60 and the plate members 10 and 20 may use the same material, and stainless steel may be used as the material. The sealing part 610 is not limited to a welding part and may be provided through a method such as caulking. The conductive resistance sheet 60 may be provided in a curved shape. Accordingly, the distance of heat conduction of the conductive resistance sheet 60 is provided longer than the linear distance of each plate member, so that the amount of heat conduction can be further reduced.

A temperature change occurs along the conductive resistance sheet 60 . Therefore, in order to block the heat transfer with the outside, it is preferable that the shielding part 62 is provided on the outside of the conductive resistance sheet 60 so that the heat insulating action occurs. In other words, in the case of a refrigerator, the second plate member 20 is at a high temperature and the first plate member 10 is at a low temperature. In addition, the conductive resistance sheet 60 undergoes heat conduction from high temperature to low temperature, and the temperature of the sheet changes rapidly along the heat flow. Therefore, when the conductive resistance sheet 60 is opened to the outside, heat transfer through the open place may occur severely. In order to reduce such heat loss, a shielding part 62 is provided on the outside of the conductive resistance sheet 60 . For example, even when the conductive resistance sheet 60 is exposed to either a low temperature space or a high temperature space, the conductive resistance sheet 60 does not perform the role of conductive resistance as much as the exposed amount, which is undesirable. do.

The shielding part 62 may be provided as a porous material in contact with the outer surface of the conductive resistance sheet 60, or may be provided as a heat insulating structure exemplified by a separate gasket placed on the outside of the conductive resistance sheet 60. , when the vacuum insulator on the main body side is closed with respect to the vacuum insulator on the door side, it may be provided as a part of the vacuum insulator provided at a position facing the corresponding conductive resistance sheet 60 . In order to reduce heat loss even when the body and the door are opened, it is preferable that the shielding part 62 is provided with a porous material or a separate heat insulating structure.

The conductive resistance sheet shown in FIG. 4B can be preferably applied to the door-side vacuum insulator, and the different parts will be described in detail with respect to FIG. 4A, and the same description will be applied to the same parts. A side frame 70 is further provided outside the conductive resistance sheet 60 . The side frame 70 may include parts for sealing the door and the body, an exhaust port necessary for an exhaust process, and a getter port for maintaining a vacuum. This is because, in the case of the vacuum insulator on the main body side, it may be convenient to install parts, but the position of the door side is limited.

In the case of the door-side vacuum insulator, it is difficult for the conductive resistance sheet 60 to be placed on the front end of the vacuum space, that is, on the side of the corner. This is because the corner edge portion of the door 3 is exposed to the outside unlike the body. In more detail, when the conductive resistance sheet 60 is placed on the front end of the vacuum space portion, the corner edge portion of the door 3 is exposed to the outside, so a separate heat insulating part must be constructed for the insulation of the conductive resistance sheet 60 Because there are disadvantages.

The conductive resistance sheet shown in FIG. 4C may be preferably installed in a pipe passing through the vacuum space, and different parts will be described in detail with respect to FIGS. 4A and 4B, and the same description will be applied to the same parts. The peripheral portion where the conduit 64 is provided may be provided in the same shape as that of FIG. 4A , and more preferably, a corrugated conductive resistance sheet 63 may be provided. According to this, the heat transfer path can be lengthened and deformation due to the pressure difference can be prevented. In addition, a separate shield for insulation of the conductive resistance sheet may be provided.

A heat transfer path between the first plate member 10 and the second plate member 20 will be described with reference to FIG. 4A again. The heat passing through the vacuum insulator includes a surface of the vacuum insulator, more specifically, a surface conductive heat (①) transmitted along the conductive resistance sheet 60, and a supporting unit 30 provided inside the vacuum insulator. ) can be divided into supporter conduction heat (②), gas conduction heat through the internal gas of the vacuum space (③), and radiant transfer heat transferred through the vacuum space portion (④).

The transfer heat may be modified according to various design values. For example, the supporting unit can be changed so that the first and second plate members 10 and 20 can withstand the vacuum pressure without being deformed, the vacuum pressure can be changed, and the interval length of the plate members can be varied, The length of the conduction resistance unit may be changed, and may vary depending on how much the temperature difference between the spaces (the first space and the second space) provided by the plate member is made. In the case of the embodiment, a preferable configuration was found when considering that the total heat transfer amount is made smaller than the heat-insulating structure provided by foaming the conventional polyurethane. Here, the actual heat transfer coefficient in the conventional polyurethane foaming refrigerator may be presented as 19.6 mW/mK.

If the heat transfer amount of the vacuum insulator according to the embodiment is relatively analyzed, heat transfer by the gas conduction heat (③) can be made the smallest. For example, this can be controlled to less than 4% of the total heat transfer. Heat transfer by solid conduction heat, which is defined as the sum of the surface conduction heat (①) and the supporter conduction heat (②), is the largest. For example, it can reach 75%. The radiation transfer heat (③) is smaller than the solid conduction heat, but larger than the heat transfer by gas conduction heat. For example, the radiation transfer heat (③) may account for approximately 20% of the total heat transfer amount.

According to this heat transfer distribution, the effective heat transfer coefficient (eK) (W/mK) may have the order of Equation 1 when comparing the heat transfer heat (①②③④).

Here, the real heat transfer coefficient (eK) is a value that can be measured using the shape and temperature difference of the target article, and is a value that can be obtained by measuring the total heat transfer amount and the temperature of at least one part to which heat is transferred. For example, by placing a quantitatively measurable heating source in the refrigerator, the amount of heat is known (W), the temperature distribution of the door is measured for the heat transmitted through the door body of the refrigerator and the edge of the door, respectively (K), and the heat is transmitted The actual heat transfer coefficient can be obtained by confirming the path that becomes a converted value (m).

The actual heat transfer coefficient (eK) of the entire vacuum insulator is a value given by k=QL/AΔT, Q is the heat transfer amount (W) and can be obtained by using the calorific value of the heater, and A is the The cross-sectional area (m ² ), L is the thickness (m) of the vacuum insulator, ΔT can be defined as a temperature difference.

The surface conduction heat is the temperature difference (ΔT) at the entrance and exit of the conductive resistance sheet 60 and 63, the cross-sectional area of the conductive resistance sheet (A), the length of the conductive resistance sheet (L), and the thermal conductivity of the conductive resistance sheet (k) ( The thermal conductivity of the conductive resistance sheet can be found out in advance as the physical properties of the material) to find out the amount of conduction heat. The supporter conduction heat, the temperature difference (ΔT) at the entrance and exit of the supporting unit 30, the cross-sectional area (A) of the supporting unit, the length (L) of the supporting unit, the thermal conductivity of the supporting unit (k). . Here, the thermal conductivity of the supporting unit can be found in advance as a physical property value of the material. The sum of the gas conduction heat (③) and the radiation transfer heat (④) can be found by subtracting the surface conduction heat and the supporter conduction heat from the heat transfer amount of the entire vacuum insulator. The ratio of the gas conduction heat to the radiative transfer heat can be found out by finding the radiant transfer heat when the vacuum degree of the vacuum space is significantly lowered so that there is no gas conduction heat.

When the porous material is provided inside the vacuum space unit 50, the porous material conduction heat (⑤) can be considered as the sum of the supporter conduction heat (②) and radiant heat (④). The heat of conduction of the porous material may be changed by various variables such as the type and amount of the porous material.

_{According to the embodiment, it is preferable that the temperature difference (ΔT 1} ) between the geometric center formed by the adjacent bars 31 and where the bars are located is less than 0.5°C. _{In addition, the temperature difference (ΔT 2} ) between the geometric center formed by the adjacent bars and the edge portion of the vacuum insulator may preferably be provided to be less than 5 degrees Celsius. In addition, in the second plate member, at a point where the heat transfer path passing through the conduction resistance sheets 60 and 63 meets the second plate member, the temperature difference with the average temperature of the second plate member may be greatest. have. For example, when the second space is a hotter region than the first space, the temperature becomes the lowest at the point of the second plate member where the heat transfer path passing through the conductive resistance sheet meets the second plate member. Similarly, when the second space is a region that is colder than the first space, the temperature becomes the highest at the point of the second plate member where the heat transfer path passing through the conductive resistance sheet meets the second plate member.

This means that the amount of heat transfer through other places except for the surface conduction heat passing through the conductive resistance sheet should be sufficiently controlled, and only when surface conduction heat occupies the largest heat transfer amount, the total amount of heat transfer satisfied by the vacuum insulator as a whole can be achieved. It means getting an advantage. To this end, the temperature change amount of the conductive resistance sheet may be controlled to be greater than the temperature change amount of the plate member.

Physical characteristics of each component providing the vacuum insulator will be described. In the vacuum insulator, a force by vacuum pressure is applied to all parts. Therefore, it is preferable to use a material having a certain level of strength (N/m ^{2 ).}

Under this background, it is preferable that the plate members 10 and 20 and the side frame 70 are made of a material having sufficient strength not to be damaged despite vacuum pressure. For example, when the number of bars 31 is reduced to limit supporter conduction heat, deformation of the plate member by vacuum pressure may occur, which may adversely affect the appearance. The radiation-resisting sheet 32 is preferably an article that can be easily processed into a thin film with low emissivity, and must have a degree of strength that is not deformed by external impact. The supporting unit 30 must be provided with strength to support the force by vacuum pressure and withstand external impact and have workability. The conductive resistance sheet 60 is preferably made of a thin plate-like material that can withstand vacuum pressure.

In an embodiment, the plate member, the side frame, and the conductive resistance sheet may be made of stainless steel having the same strength. The radiation resistance sheet may be made of aluminum having a weaker strength than stainless steel. The supporting unit may use a resin having a weaker strength than aluminum as its material.

Unlike the strength seen in terms of the material as described above, an analysis in terms of rigidity is required. The stiffness (N/m) is a property that is not easily deformed, and even if the same material is used, the stiffness may vary depending on the shape thereof. The conductive resistance sheets 60 and 63 may be made of a material with high strength, but it is preferable to increase the thermal resistance and to spread evenly without a rough surface when vacuum pressure is applied to minimize the radiated heat. The radiation resistance sheet 32 is required to have a certain level of rigidity in order not to touch other parts due to deformation. In particular, the edge portion of the radiation resistance sheet may sag according to its own weight to generate conductive heat. Therefore, a certain level of rigidity is required. The supporting unit 30 is required to be rigid enough to withstand the compressive stress and external impact from the plate member.

In the embodiment, it is preferable that the plate member and the side frame have the highest rigidity to prevent deformation due to vacuum pressure. Preferably, the supporting unit, particularly the bar, has the second greatest stiffness. The radiation resistance sheet is weaker than the supporting unit, but it is preferable to have rigidity than the conductive resistance sheet. Lastly, it is preferable that the conductive resistance sheet be easily deformed by vacuum pressure, so it is preferable to use a material with the lowest rigidity.

Even when the inside of the vacuum space 50 is filled with the porous material 33, it is preferable that the conductive resistance sheet have the lowest rigidity, and it is preferable that the plate member and the side frame have the highest rigidity.

5 is a cross-sectional view of the conductive resistance sheet and the first plate member.

Referring to FIG. 5 , the conduction resistance sheet 60 is connected to the first plate member 10 and may resist heat conduction flowing along the wall of the vacuum space.

The conductive resistance sheet 60 includes curved portions 63 and 65 formed by being depressed into the vacuum space and a seating portion 67 seated on the first plate member.

The thickness t1 of the conductive resistance sheet 60 is thinner than the thickness of the first plate member 10 . As the thickness t1 of the conductive resistance sheet 60 decreases, heat transfer through the first plate member 10 is minimized, thereby improving the thermal insulation effect. Specifically, in order to satisfy the thermal conductivity condition, the thickness t1 of the conductive resistance sheet 60 should be designed to be 300 μm or less. However, in order for the conductive resistance sheet 60 to support atmospheric pressure, it must be designed to have a predetermined thickness or more.

The thickness t1 of the conductive resistance sheet 60 may be manufactured to a level of 0.05 mm. However, the thickness t1 of the conductive resistance sheet 60 may be determined differently depending on the material and shape of the conductive resistance sheet 60 .

The conductive resistance sheet 60 may be made of stainless steel, titanium, or iron. This is because the material has low thermal conductivity and sufficiently high strength characteristics. In addition, the conductive resistance sheet 60 may be made of a material of precipitation hardening stainless steel (AM350), and since the precipitation hardening stainless steel (AM350) has 3 to 4 times the strength of conventional stainless steel, the risk of breakage is reduced.

The curved portions 63 and 65 include a first curved portion 63 and a second curved portion 65 . The first curved portion 63 may be formed in a shape that is depressed toward the vacuum space portion. The second curved portion 65 extends from both ends of the first curved portion 63 .

The second curved portion 65 is disposed to surround the edge portion of the first plate member 10 . Since the conductive resistance sheet 60 is made of a thin material, it is vulnerable to strength. Accordingly, damage to the conduction resistance sheet 60 can be prevented by forming a rounded edge of the first plate member 10 .

Meanwhile, the edge portion of the first plate member 10 may be chamfered to correspond to a direction in which the second curved portion 65 is curved.

A coupling part 61 for fixing the conductive resistance sheet 60 to the first plate member 10 is formed in the seating part 67 . The coupling part 61 may be formed by welding. Therefore, the coupling part 61 may be called a welding part.

Meanwhile, the conductive resistance sheet 60 may be made of a material similar to that of the first plate member 10 . This is to facilitate welding between the conductive resistance sheet 60 and the first plate member 10 .

When the seating portion 67 is welded to the first plate member 10 , the conductive resistance sheet 60 is deformed by heat, and between the seating portion 67 and the first plate member 10 . gaps may occur. In this case, the vacuum degree of the vacuum space part is not maintained, so that the insulation effect may be reduced. Therefore, when welding the seating portion 67, welding should be performed after pressing the peripheral portion of the portion to be welded using a jig. Accordingly, the seating portion 67 may be in close contact with the first plate member 10 .

Accordingly, the welding portion 61 may be spaced apart from the edge portion of the first plate member 10 by a predetermined length. Specifically, the length d1 from the welding portion 61 to the boundary portion 66 between the second curved portion 65 and the seating portion 67 should be secured as much as a space to be pressed with a jig. The length of d1 may be set to at least 5 mm.

In this case, the length d2 from the welding part 61 to the first curved part 63 and the second curved part 65 may be designed to be 7 mm or more.

The first curved portion 63 has a downwardly convex shape, and the second curved portion 65 has an upwardly convex shape. That is, the curvature R1 of the first curved portion 63 and the curvature R2 of the second curved portion 65 have different signs. The boundary portion 64 between the first curved portion 63 and the second curved portion 65 may be formed to have zero curvature.

The curvature R2 of the second curved portion 65 may satisfy the following relational expression.

t2 denotes a vertical distance from the seating portion 67 to the boundary portion 64 between the first curved portion 63 and the second curved portion 65 .

The second curved portion 65 forms a curved surface, and the seating portion 67 forms a flat surface. Accordingly, a flat surface is formed on the left side and a curved surface is formed on the right side based on the boundary portion 66 between the second curved portion 65 and the seating portion 67 .

6 is a graph for explaining the design criteria of the conductive resistance sheet.

Referring to FIG. 6 , the following equation between x and y is applied to the horizontal axis graph of the graph.

Here, x means (depth of conductive resistance sheet)/(width of conductive resistance sheet)^2, and y means (minimum thickness of conductive resistance sheet)*(permissible strength of conductive resistance sheet). That is, if the depth, width, and allowable strength of the conductive resistance sheet 60 are known, the minimum thickness t1 of the conductive resistance sheet can be obtained. Here, the allowable strength of the conductive resistance sheet corresponds to the breaking strength of 240 MPa. However, the allowable strength may be changed according to the material of the conductive resistance sheet 60 .

The depth (H) of the conductive resistance sheet 60 means the vertical distance from the seating portion 71 of the conductive resistance sheet 60 to the lowest point of the first curved portion 63, and the conductive resistance sheet ( The width L of 60) means the width in the transverse direction of the conductive resistance sheet 60 , and the allowable strength of the conductive resistance sheet 60 is a value determined according to the material of the conductive resistance sheet 60 .

Through the graph, if the width (L) of the conductive resistance sheet 60 is constant, as the depth (H) of the conductive resistance sheet 60 is shallower, the minimum thickness value of the conductive resistance sheet 60 is exponentially increased. will increase Accordingly, when the cross-section of the conductive resistance sheet 60 is semicircular or arcuate, the minimum thickness of the conductive resistance sheet 60 can be made thin, and thus, thermal insulation performance can be improved.

The thickness of the conductive resistance sheet 60 should be manufactured to be 300 μm or less. This is because, as the thickness of the conductive resistance sheet 60 decreases, the effect of blocking the cold air transmitted from the first plate member 10 increases. That is, as the thickness of the conductive resistance sheet 60 decreases, thermal conductivity may decrease.

Meanwhile, the thickness of the vacuum insulator may be designed to be 3 mm or more and 30 mm or more in order to satisfy the minimum strength condition and the optimum volume condition. At this time, when the conductive resistance sheet 60 is disposed as shown in FIG. 4(a), the diameter of the semicircle formed by the cross section of the conductive resistance sheet 60 can be approximated to the thickness of the vacuum insulator, so that the The range of the diameter of the semicircle formed by the cross section of the conductive resistance sheet 60 is also designed to be 3 mm or more and 30 mm or more.

Accordingly, the range of the depth of the conductive resistance sheet 60 is designed to be 1.5 mm or more and 15 mm or less, like the radius of a semicircle formed by the cross section of the conductive resistance sheet 60 .

If the range of the depth of the conductive resistance sheet 60 is 1.5 mm or more and 15 mm or less, and the range of the width of the conductive resistance sheet 60 is 3 mm or more and 30 mm or less, the range of the x value on the graph is 0.0167 or more and 0.167 or less. corresponds to When the allowable strength of the conductive resistance sheet is calculated as 240 MPa, the minimum thickness range of the conductive resistance sheet 60 may be set to 0.57 μm or more and 3.98 μm or less. That is, when the thickness of the vacuum insulator is designed to satisfy the minimum strength condition and the optimum volume condition, the minimum thickness range of the conductive resistance sheet 60 may be designed to be 0.57 μm or more and 3.98 μm or less.

7 is a view showing the action of atmospheric pressure on the conductive resistance sheet, and FIG. 8 is a diagram for explaining the relationship between the atmospheric pressure and the tension acting on the conductive resistance sheet.

7 and 8 , the total load applied to the conductive resistance sheet 60 corresponds to the product of atmospheric pressure and the width L of the conductive resistance sheet 60 . A distributed load by atmospheric pressure acts vertically on the surface of the conductive resistance sheet 60 . If this is integrated, it can be expressed as one concentrated load. The magnitude of the concentrated load is a curve of the width L of the conductive resistance sheet 60 and atmospheric pressure, and the direction acts as the center of the arc of the conductive resistance sheet.

When the atmospheric pressure acting on the conductive resistance sheet 60 and the tension applied to both ends of the conductive resistance sheet 60 are balanced, the following relational expression is satisfied.

Here, Fy and P satisfy the following equation.

Here, σ means the stress acting on the conductive resistance sheet 60, t means the thickness of the conductive resistance sheet 60, A means atmospheric pressure, L is the conductive resistance sheet 60 means the width of

Therefore, the stress σ acting on the conductive resistance sheet 60 satisfies the following equation.

The strength of the conductive resistance sheet 60 should be greater than or equal to the stress, and in order to reduce the stress applied to the conductive resistance sheet 60 as much as possible, θ should be set large. That is, it is advantageous as the conductive resistance sheet 60 has a shape close to a semicircle. In addition, even when the thickness t of the conductive resistance sheet 60 is increased, the stress applied to the conductive resistance sheet 60 can be reduced.

Hereinafter, a vacuum pressure preferably suggested according to the internal state of the vacuum insulator will be described. As already described, the inside of the vacuum insulator must maintain a vacuum pressure to reduce heat transfer. In this case, it can be easily predicted that it is desirable to maintain a vacuum pressure as low as possible to reduce heat transfer.

The vacuum space may resist heat transfer only by the supporting unit 30, and the porous material 33 may be filled with the supporting unit in the vacuum space 50 to resist heat transfer, and the supporting unit may be It is also possible to resist heat transfer with a porous material without application.

A case in which only the supporting unit is provided will be described.

9 is a graph showing a change in thermal insulation performance and a change in gas conductivity according to vacuum pressure by applying a simulation.

Referring to FIG. 9 , as the vacuum pressure decreases, that is, as the degree of vacuum increases, the heat load in the case of only the body (graph 1) or when the body and the door are combined (graph 2), compared with the conventional polyurethane foamed article Therefore, it can be seen that the heat load is reduced and the thermal insulation performance is improved. However, it can be seen that the degree of improvement in the thermal insulation performance is gradually lowered. In addition, it can be seen that the lower the vacuum pressure, the lower the gas conductivity (graph 3). However, it can be seen that even if the vacuum pressure is lowered, the rate at which the thermal insulation performance and gas conductivity are improved gradually decreases. Therefore, although it is preferable to lower the vacuum pressure as much as possible, there are problems in that it takes a lot of time to obtain an excessive vacuum pressure, and costs are high due to the use of an excessive getter. In the embodiment, the optimum vacuum pressure is proposed from the above point of view.

10 is a graph for observing the process of evacuating the inside of the vacuum insulator with time and pressure when the supporting unit is used.

Referring to FIG. 10 , in order to form the vacuum space part 50 in a vacuum state, while heating (baking), the gas of the vacuum space part is exhausted by a vacuum pump while vaporizing the potential gas remaining in the parts of the vacuum space part. However, when the vacuum pressure exceeds a certain level, it reaches a point where the level of the vacuum pressure no longer increases (Δt ₁ ). After that, the connection of the vacuum space of the vacuum pump is disconnected and heat is applied to activate the getter (Δt ₂ ). When the getter is activated, the pressure in the vacuum space decreases for a certain period of time, but it is normalized and the vacuum pressure is maintained at a certain level. When the vacuum pressure is maintained at a certain level after activation of the getter, the vacuum pressure is approximately 1.8×10 ^-6 Torr.

^{In the embodiment, the lowest internal pressure of the vacuum space is 1.8×10 -6} Torr by setting the point at which the vacuum pressure is no longer substantially lowered even when the gas is exhausted by operating the vacuum pump as the lower limit of the vacuum pressure used in the vacuum insulator. set to

11 is a graph comparing vacuum pressure and gas conductivity.

Referring to FIG. 11 , the actual heat transfer coefficient (eK) of the gas conductivity according to the vacuum pressure according to the size of the gap between the inside of the vacuum space part 50 is shown as a graph. The gap of the vacuum space part was measured in three cases of 2.76 mm, 6.5 mm, and 12.5 mm. The gap of the vacuum space is defined as follows. When there is the radiation resistance sheet 32 inside the vacuum space part, it is the distance between the radiation resistance sheet and an adjacent plate, and when there is no radiation resistance sheet inside the vacuum space part, the first plate member and the second plate member The distance between the two plate members.

The point corresponding to the conventional real heat transfer coefficient of 0.0196 W/mk for providing an insulating material by foaming polyurethane was found to be 2.65×10 ⁻¹ Torr even when the size of the gap was 2.76 mm due to the small size of the gap. On the other hand, even if the vacuum pressure is lowered, it was confirmed that the point at which the reduction effect of the insulation effect due to the gas conduction heat is saturated is approximately 4.5×10 ^{-3 Torr.} The pressure of 4.5×10 ^-3 Torr may be determined as the point at which the reduction effect of gas conduction heat is saturated. Also, when the real heat transfer coefficient is 0.1 W/mk, it is 1.2×10 ^-2 Torr.

When the supporting unit is not provided in the vacuum space and the porous material is provided, the size of the gap ranges from several micrometers to several hundreds of micrometers. In this case, even when the vacuum pressure is relatively high due to the porous material, that is, even when the degree of vacuum is low, radiant heat transfer is small. Therefore, an appropriate vacuum pump suitable for the vacuum pressure is used. The appropriate vacuum pressure for the corresponding vacuum pump is approximately 2.0×10 ^-4 Torr. In addition, the vacuum pressure at the point where the effect of reducing the gas conduction heat is saturated is approximately 4.7×10 ⁻² Torr. In addition, the pressure at which the reduction effect of gas conduction heat reaches the conventional real heat transfer coefficient of 0.0196 W/mk is 730 Torr.

When the supporting unit and the porous material are provided together in the vacuum space, a vacuum pressure intermediate between the case of using only the supporting unit and the case of using only the porous material may be used.

The vacuum insulator presented in the present invention is preferably applied to a refrigerator. However, the application of the vacuum insulator is not limited to the refrigerator, and may be applied to various places such as a cryogenic refrigeration device, a heating device, and a blower device.

The present invention enables the vacuum insulator to be industrially applied to various thermal insulation facilities. It is possible to increase the energy use efficiency by increasing the insulation effect and to increase the effective capacity of the facility, so urgent industrial application is actively expected.

Claims (20)

a first plate member defining at least a portion of a wall for the first space;
a second plate member defining at least a portion of a wall for a second space having a temperature different from that of the first space;
a sealing part sealing the first plate member and the second plate member so as to provide a third space that is a temperature between the temperature of the first space and the temperature of the second space and is a space in a vacuum state;
a supporting unit for maintaining the third space;
a heat resistance unit for reducing an amount of heat transfer between the first plate member and the second plate member;
an exhaust port for discharging the gas of the third space;
a conductive resistance sheet provided as the heat resistance unit, connected to at least one of the plate members, and capable of resisting heat conduction flowing along the wall of the third space;
a seating portion included in the conductive resistance sheet and seated on at least one of the first plate member and the second plate member; and
At least one curved portion included in the conductive resistance sheet, at least a portion of which is recessed into the third space, is included;
At least one of the curved parts is a vacuum insulator that curves and surrounds an end of at least one of the first plate and the second plate so that the conductive resistance sheet is not damaged by the vacuum pressure of the third space. The method of claim 1,
At least one of the curved portion is a vacuum insulator surrounding the curved end of at least one of the first plate and the second plate. The method of claim 1,
The mounting portion includes a coupling portion for fixing the conductive resistance sheet to at least one of the first plate member and the second plate member. 4. The method of claim 3,
A vacuum insulator including a welding part in the coupling part. 5. The method of claim 4,
The welding portion is a vacuum insulator spaced apart from the edge portion of the plate member by a predetermined length. The method of claim 1,
The conductive resistance sheet is a vacuum insulator thinner than at least one of the first plate member and the second plate member. a first plate member defining at least a portion of a wall for the first space;
a second plate member defining at least a portion of a wall for a second space having a temperature different from that of the first space;
a sealing part sealing the first plate member and the second plate member so as to provide a third space that is a temperature between the temperature of the first space and the temperature of the second space and is a vacuum space;
a supporting unit for maintaining the third space;
a heat resistance unit for reducing an amount of heat transfer between the first plate member and the second plate member;
an exhaust port for discharging the gas of the third space;
a conductive resistance sheet provided as the heat resistance unit, connected to at least one of the plate members, and capable of resisting heat conduction flowing along the wall of the third space;
a seating portion included in the conductive resistance sheet and mounted on the plate member; and
At least one curved portion included in the conductive resistance sheet, at least a portion of which is recessed into the third space, is included;
The curved portion includes a first curved portion that is depressed toward the third space, and a second curved portion that extends from the first curved portion and wraps around at least a portion of the plate member,
A vacuum insulator including a boundary portion lying on the boundary between the first curved portion and the second curved portion and having a curvature of 0. 8. The method of claim 7,
The second curved portion is a vacuum insulator surrounding at least one end of the first plate and the second plate by bending. 8. The method of claim 7,
The seating portion is a vacuum insulator connected to the second curved portion. 8. The method of claim 7,
When the curvature of the second curved portion is R and the vertical distance from the seating portion to the boundary portion is t, t/10 < R is satisfied. a plate member forming a vacuum space;
a conductive resistance sheet connected to the plate member;
a supporting unit for maintaining the vacuum space;
a seating portion included in the conductive resistance sheet and mounted on the plate member; and
Contained in the conductive resistance sheet, at least a part of which includes at least one curved portion recessed into the vacuum space portion,
The curved portion includes a first curved portion that is recessed toward the vacuum space to reduce conduction heat,
The curved portion is rounded by bending the periphery of the plate member so that the portion in contact with the conductive resistance sheet and the plate is not damaged by the tensile stress applied to the conductive resistance sheet by the vacuum pressure of the vacuum space portion. A vacuum insulator including a second curved portion surrounding it. 12. The method of claim 11,
The seating portion and the curved portion are continuous vacuum insulator. 12. The method of claim 11,
A periphery of the plate member is an end portion of the plate member. 12. The method of claim 11,
The second curved portion is a vacuum insulator adjacent to the seating portion. 12. The method of claim 11,
The seating portion may include a portion coupled to the plate member and a portion not coupled to the plate member. 12. The method of claim 11,
A vacuum insulator forming a flat surface toward the seating portion and a curved surface toward the curved portion based on a boundary portion that is a boundary between the seating portion and the curved portion. 12. The method of claim 11,
A vacuum insulator in which the radius of curvature of the first curved portion is greater than the radius of curvature of the second curved portion. a first plate member defining at least a portion of a wall for the first space;
a second plate member defining at least a portion of a wall for a second space having a temperature different from that of the first space;
a sealing part sealing the first plate member and the second plate member so as to provide a third space that is a temperature between the temperature of the first space and the temperature of the second space and is a space in a vacuum state;
a supporting unit for maintaining the third space;
a heat resistance unit for reducing an amount of heat transfer between the first plate member and the second plate member;
an exhaust port for discharging the gas of the third space;
a conductive resistance sheet provided as the heat resistance unit, connected to at least one of the plate members, and capable of resisting heat conduction flowing along the wall of the third space;
a seating part included in the conductive resistance sheet and mounted on at least one of the first plate member and the second plate member; and
Included in the conductive resistance sheet, a curved portion of a curved shape is included,
The curved portion includes a first curved portion that is depressed toward the third space,
The curved portion includes a second curved portion extending from the seating portion,
At least one of the curved portions is a vacuum insulator surrounding at least a portion of at least one of the first plate and the second plate to be rounded. 19. The method of claim 18,
The first curved portion and the second curved portion are vacuum insulators having opposite curvature directions. 19. The method of claim 18,
The second curved portion is a vacuum insulator surrounding at least one end of the first plate and the second plate.

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