JP4097096B2 - Insulation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat insulator for use in a heat retaining and cooling device such as a refrigerator.
[0002]
[Prior art]
FIG. 11 is a cross-sectional view of a conventional heat insulator described in, for example, Japanese Patent Laid-Open No. 61-235671. It is known that when the gas stored in the open cell structure of a predetermined size is depressurized below a predetermined pressure, the thermal conductivity rapidly decreases due to the lean gas effect. A conventional heat insulator is manufactured by utilizing this rare gas effect, and a porous material layer 1 which is a rigid urethane foam having an open cell structure is accommodated in a container 3 made of a metal-plastic laminate film. Furthermore, the air inside the container 3 is made to be depressurized below a predetermined pressure.
[0003]
In order to further improve the heat insulation performance, in the heat insulator described in the above Japanese Patent Application Laid-Open No. 61-235671, the porous material layer 1 is perpendicular to the direction of temperature movement from a high temperature to a low temperature, that is, the heat flow direction. It is cut into a plurality of thin plates, and the thin plates are stacked and stored. Since the thermal resistance increases at the joining surfaces of the thin plates, the heat insulation performance of the heat insulator is improved.
[0004]
FIG. 12 is a schematic view of a joint surface portion of the laminated porous material layer 1. When the degree of vacuum of the air in the container 3 is less than or equal to a predetermined value, the heat hardly propagates through the communicating bubble portion, and is conducted along the skeleton 10 of the porous material layer 1 as shown by the arrows in FIG. Is done. Therefore, the heat insulation performance of the heat insulator depends on the thermal conductivity of the urethane itself forming the skeleton 10, the cross-sectional area of the skeleton 10, and the length of the heat transfer path. Therefore, the smaller the cross-sectional area of the skeleton 10 and the longer the total length of the heat transfer path of the skeleton 10, the better the heat insulation performance.
[0005]
On the other hand, in the series of porous material layers 1 foamed at the same time, the skeleton 10 formed inside is isotropically distributed in a mesh pattern without being interrupted in the middle. Therefore, macroscopically, the length of the heat transfer path of the heat flowing in the thickness direction (heat flow direction) of the porous material layer 1 is the thickness of the porous material layer 1 or slightly longer than this. It wo n’t go much beyond.
[0006]
The prior art described in JP-A-61-2235671, in which the porous material layer 1 is cut into a thin plate and stacked, is partially interrupted during the heat transfer through the skeleton 10. , Has succeeded in improving the insulation performance. The heat transfer at the joint surface (blocking portion) is conducted through the rare air or through the contacted portion of the skeleton 10, but the heat conducted through the lean air is slight. Many of which are conducted through the contact portion of the skeleton 10. Therefore, the heat reaching the non-contact portion is detoured and conducted from the contact portion, and the heat transfer path is lengthened, so that the heat insulation performance is improved.
[0007]
[Problems to be solved by the invention]
However, in the conventional heat insulator having such a configuration, the length of the heat transfer path detouring at the joint surface is not much longer, and the improvement degree of the heat insulation performance is about 20% at most, A significant improvement in heat insulation performance could not be expected.
[0008]
This invention was made in order to solve the above problems, and it aims at obtaining the heat insulating body which has high heat insulation performance.
[0009]
[Means for Solving the Problems]
The heat insulating body according to claim 1, wherein a porous material layer having an open cell structure and a fibrous material layer in which fibers are arranged so as to extend in a direction substantially perpendicular to the heat flow direction are alternately laminated in the heat flow direction. A laminated body and a container in which the laminated body is housed and the inside is decompressed, and a spacer having a predetermined thickness is disposed between adjacent porous material layers, and the fibrous material layer is porous. A gap formed between the porous material layers is filled with a fibrous material .
[0012]
In the heat insulator of claim 2 , the spacer protrudes integrally with the main surface of the porous material layer.
[0013]
In the heat insulator of claim 3 , the spacer is formed with a communication port through which air in the fibrous material layer is sucked.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a sectional view showing a heat insulator of the present invention. In the heat insulator of this embodiment, a laminated body 4 in which a porous material layer 1 made of a rigid urethane foam having an open cell structure and a fibrous material layer 2 made of a fibrous material are alternately stacked is a bag-like container 3. The air inside the container 3 is further reduced in pressure. As the container 3, a bag is used in which an aluminum-laminated resin sheet is formed so that the degree of vacuum during decompression is maintained for a long time.
[0015]
As shown in FIG. 2, spacers 7 made of a hard material having a strength that does not cause buckling or the like with respect to atmospheric pressure are arranged at equal intervals around the porous material layer 1 at predetermined intervals. It is arranged. The spacer 7 forms a space between the stacked porous material layers 1. The fibrous material layer 2 is formed by filling this space with a fibrous material. As the fibrous material, a material having low thermal conductivity such as pulp is used. And the direction of the fiber of a fibrous material is arrange | positioned so that it may become substantially parallel to the main surface of the porous material layer 1, ie, it extends in a substantially perpendicular direction with respect to a heat flow direction. The material of the spacer 7 is preferably a material having a strength that does not cause buckling or the like with respect to atmospheric pressure and a good heat insulating performance. For example, a hard material having the same open cell structure as the porous material layer 1 is used. It is preferably composed of urethane foam.
[0016]
FIG. 3 is a perspective view of a laminate 4 in which porous material layers 1 and fibrous material layers 2 are alternately laminated. The gap formed between the adjacent spacers 7 becomes a communication port 6 for communication between the fibrous material layer 2 and the outside during lamination. When the laminated body 4 is accommodated in the container 3 and then depressurized, the air inside the fibrous material layer 2 is sucked from the communication port 6 and depressurized. For this reason, by making the size of the communication port 6 appropriate, the air inside the fibrous material layer 2 can be sucked well, and a predetermined degree of vacuum can be obtained in a short time. This shortens the manufacturing time of the insulation.
[0017]
Next, the heat insulation mechanism of this heat insulator will be described. FIG. 4 is an enlarged schematic view of the joint surface portion between the porous material layer 1 and the fibrous material layer 2. The direction of the macroscopic heat flow is indicated by a thick white arrow 13 in FIG. 4, and the microscopic heat flow is indicated by a black arrow 14. When the porous material layer 1 having the open cell structure is enlarged, it is composed of a skeleton 10 and open cells 11 as shown in FIG.
[0018]
In the porous material layer 1, if the distance L [m] between two adjacent skeletons 10 is exponentially equal to the mean free process Lf [m] of the gas, the communicating bubble 11 is generated due to the rare gas effect. The thermal conductivity of the gas present inside falls sharply. When the gas in the communication bubble 11 is air, the thermal conductivity λ [W / mK] of air is calculated as follows from the distance L [m] and the mean free path Lf [m] of air.
λ = 0.0261 / (1 + 15/4 × Lf / L) [W / mK]
[0019]
On the other hand, the mean free path Lf [m] of gas molecules is inversely proportional to the pressure P [Torr]. And when gas is air, it calculates | requires with the following formula | equation.
Lf = 0.07 × 10 ^-6 × 760 / P
Therefore, the thermal conductivity λ [W / mK] of the air is
λ = 0.0261 / {1 + 15/4 × 0.07 × 10 ⁻⁶ × 760 / (P × L) [W / mK]
Sought by.
FIG. 5 shows the relationship between the thermal conductivity λ [W / mK] obtained from this equation, the pressure P [Torr], and the distance L [m]. Generally, the degree of vacuum that can be industrially efficiently produced is around 1 Torr. According to FIG. 5, the distance L [m] at which the thermal conductivity sharply decreases in the vicinity of the degree of vacuum of 1 Torr is 100 μm. Therefore, if the distance L [m] between the skeletons 10 is set to 100 μm or less, a heat insulation effect can be obtained efficiently. This effect is the same also in the fibrous material layer 2, and if the distance between the fibers 12 is 100 μm or less, a heat insulating effect can be obtained efficiently.
[0020]
In the present embodiment, the distance L [m] between the communicating bubbles 11 and the fibers of the fibrous material layer 2 is approximately 100 μm or less. The degree of vacuum is approximately 1 Torr or less. Therefore, very little heat is transmitted through the lean air, and the heat is mainly transmitted through the skeleton 10 and the fibers 12.
[0021]
Heat conduction from the porous material layer 1 to the fibrous material layer 2 is performed through the contact portion between the skeleton 10 and the fibers 12. Since a contact thermal resistance exists between the two, the heat insulation performance is improved. Further, inside the fibrous material layer 2, heat flows along the length direction of the fibers 12, and is transferred to the adjacent fibers 12 one after another at a portion where each fiber 12 is in contact. Each fiber 12 in the fibrous material layer 2 is arranged so as to lie substantially perpendicular to the heat flow direction. Therefore, the heat transfer path becomes very long compared to the thickness of the heat insulator, and the heat insulation performance is improved. Furthermore, each fiber 12 conducts heat at a portion in contact with each other, but each contact portion has a contact thermal resistance, and the contact thermal resistance increases each time it passes through the contact portion. Is further improved.
[0022]
On the other hand, when the heat insulator is composed only of the fibrous material layer 2, when the inside of the container 3 is depressurized, the fibers 12 are compressed due to atmospheric pressure and contract in the thickness direction, and the adjacent fibers 12 contact each other. The area increases. When the contact area increases, the contact thermal resistance increases, so that the desired heat insulation performance cannot be obtained. In the present embodiment, a spacer 7 is provided on the main surface of the porous material layer 1, and the fibrous material layer 2 is disposed in a gap formed by the spacer 7 between the two porous material layers 1. Therefore, the size of the space is maintained by the spacer 7, and the fibrous material layer 2 is not subjected to compression by atmospheric pressure. For this reason, the fibrous material layer 2 does not shrink in the thickness direction, the contact area between the adjacent fibers 12 is kept small, and high heat insulating performance is maintained.
[0023]
In the heat insulator having such a configuration, the heat flow in the fibrous material layer 2 flows largely detouring along the fibers 12, so that the heat transfer path is increased and the heat insulation performance is improved. A spacer 7 having a predetermined thickness is disposed between adjacent porous material layers 1, and the fibrous material layer 2 is formed by filling this space with a fibrous material. Therefore, since it does not receive compression by atmospheric pressure and does not shrink in the thickness direction, the contact area between the adjacent fibers 12 can be kept small, and high heat insulation performance can be maintained.
[0024]
In the present embodiment, a rigid urethane foam having an open cell structure is used as the porous material layer 1, but the porous material layer 1 has an open cell structure such as styrene foam or ceramic porous material. A porous material having In addition, a resin sheet bag laminated with aluminum is used for the container 3, but any container having airtightness may be used.
[0025]
Further, in the present embodiment, the spacers 7 are arranged at equal intervals around the porous material layer 1, but the size, the number, and the installation interval of the spacers 7 are arbitrary. It goes without saying that may be different. And if the position of the communication port 6 formed between the spacers 7 is, for example, a position close to the suction port formed in order to depressurize the container 3, the air inside the fibrous material layer 2 is sucked even better. It is effective. In addition, in the present embodiment, the spacer 7 is provided only at the peripheral portion of the porous material layer 1. However, for the purpose of enhancing the strength, the spacer 7 is additionally provided at the central portion as shown in FIG. Also good.
[0026]
Embodiment 2. FIG.
FIG. 7 is a perspective view of a porous material layer and a fibrous material layer showing another example of the heat insulator of the present invention. The porous material layer 1 of the present embodiment has a generally flat recess 1b formed at the center, leaving an edge 1a having a predetermined width at the periphery. The fibrous material layer 2 is formed by filling the fibers 12 in the indented portion 1b. The porous material layer 1 is integrally formed by, for example, mold foam molding. Other configurations are the same as those of the first embodiment.
[0027]
In the heat insulator having such a configuration, since the number of spacers can be reduced, the number of parts can be reduced and the cost can be reduced. Further, the manufacturing time can be shortened.
[0028]
Embodiment 3 FIG.
FIG. 8 is a perspective view of a porous material layer showing another example of the heat insulator of the present invention. FIG. 9 is a perspective view showing a state in which a porous material layer and a fibrous material layer are laminated. The porous material layer 1 of the present embodiment is formed with a substantially flat recess 1b at the center, leaving an edge 1a of a predetermined width at the periphery, and further at the edge 1a, a recess 1b. A communication groove 1c that communicates with the outside is formed. The communication groove 1 c forms a communication port 6 in cooperation with the back surface of the adjacent porous material layer 1 in a state where the porous material layer 1 is laminated. Other configurations are the same as those of the second embodiment.
[0029]
In the heat insulator having such a configuration, since the number of spacers can be reduced, the number of parts can be reduced and the cost can be reduced. Further, the manufacturing time can be shortened. Moreover, the air inside the fibrous material layer 2 can be satisfactorily sucked, and a predetermined degree of vacuum can be obtained in a short time. This shortens the manufacturing time of the insulation.
[0030]
In the present embodiment, one communication groove 5 is provided on each side of the porous material layer 1 and the size thereof is the same, but the number may be different or the size may be different. Needless to say. Further, a rigid urethane foam having an open cell structure is used as the porous material layer 1, but the porous material layer 1 may be any porous material having an open cell structure such as a styrene foam or a ceramic porous material. good.
[0031]
Embodiment 4 FIG.
FIG. 10 is a perspective view of a porous material layer showing another example of the heat insulator of the present invention. The porous material layer 1 of the present embodiment has a generally flat recess 1b formed at the center, leaving an edge 1a having a predetermined width at the periphery. The edge portion 1a is formed with a communication hole 1d that communicates the recessed portion 1b with the outside. The communication hole 1 d constitutes a communication port that sucks air inside the fibrous material layer 2. Other configurations are the same as those of the second embodiment.
[0032]
In the heat insulator having such a configuration, since the number of spacers can be reduced, the number of parts can be reduced and the cost can be reduced. Further, the manufacturing time can be shortened. Furthermore, the air inside the fibrous material layer 2 can be satisfactorily sucked, and a predetermined degree of vacuum can be obtained in a short time. This shortens the manufacturing time of the insulation.
[0033]
In the present embodiment, the number of communication ports 6 is one for each side, but may be increased or decreased as necessary. Needless to say, the cross-sectional shape of the communication hole is not limited to a circle, and the same effect can be obtained even if the communication hole has a different shape such as a rectangle.
[0034]
【The invention's effect】
The heat insulating body according to claim 1, wherein a porous material layer having an open cell structure and a fibrous material layer in which fibers are arranged so as to extend in a direction substantially perpendicular to the heat flow direction are alternately laminated in the heat flow direction. A laminated body and a container in which the laminated body is housed and the inside is decompressed, and a spacer having a predetermined thickness is disposed between adjacent porous material layers, and the fibrous material layer is porous. A gap formed between the porous material layers is filled with a fibrous material . Therefore, the contact thermal resistance of the joint surface between the porous material layer and the fibrous material layer is large, and the heat insulation performance is improved. Moreover, since the heat flow in the fibrous material layer flows largely detouring along the fiber, the heat transfer path is increased and the heat insulation performance is improved. In addition, since the fibrous material layer is not compressed by atmospheric pressure and does not shrink in the thickness direction, the contact area between the fibers can be kept small, and high heat insulation performance can be maintained. it can.
[0037]
In the heat insulator of claim 2 , the spacer protrudes integrally with the main surface of the porous material layer. Therefore, the number of parts can be reduced and the cost can be reduced. Further, the manufacturing time can be shortened.
[0038]
In the heat insulator of claim 3 , the spacer is formed with a communication port through which air in the fibrous material layer is sucked. For this reason, the air inside the fibrous material layer can be satisfactorily sucked, and a predetermined degree of vacuum can be obtained in a short time, so that the manufacturing time of the heat insulator can be shortened.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a heat insulator according to the present invention.
FIG. 2 is a perspective view of a porous material layer and a spacer disposed on the main surface of the porous material layer.
FIG. 3 is a perspective view of a laminate in which a porous material layer and a fibrous material layer are laminated.
FIG. 4 is an enlarged schematic view of a joint portion between a porous material layer and a fibrous material layer.
FIG. 5 is a graph showing the relationship between the thermal conductivity of air, pressure, and the distance between skeletons or fibers.
FIG. 6 is a perspective view showing an example in which a spacer is disposed at the center of the main surface of the porous material layer.
FIG. 7 is a perspective view of a porous material layer and a fibrous material layer showing another example of the heat insulator of the present invention.
FIG. 8 is a perspective view of a porous material layer showing another example of the heat insulator of the present invention.
FIG. 9 is a perspective view showing a state in which a porous material layer is laminated.
FIG. 10 is a perspective view of a porous material layer showing another example of the heat insulator of the present invention.
FIG. 11 is a cross-sectional view of a conventional heat insulator.
FIG. 12 is a schematic view of a joined portion of laminated porous material layers.
[Explanation of symbols]
1 porous material layer, 1c communication groove (communication port), 1d communication hole (communication port), 2 fibrous material layer, 3 container, 4 laminate, 6 communication port, 7 spacer, 12 fibers.

Claims (3)

A laminate in which a porous material layer having an open cell structure and a fibrous material layer in which fibers are arranged so as to extend in a direction substantially perpendicular to the heat flow direction are alternately laminated in the heat flow direction;
In the heat insulator provided with a container in which the laminate is stored and the inside is decompressed ,
A spacer having a predetermined thickness is disposed between the adjacent porous material layers, and the fibrous material layer is formed by filling a void formed between the porous material layers with a fibrous material. Insulation characterized by. The heat insulating body according to claim 1 , wherein the spacer protrudes integrally with the main surface of the porous material layer. The heat insulator according to claim 1 or 2 , wherein a communication port for sucking air in the fibrous material layer is formed in the spacer.

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