CN112629130B

CN112629130B - Heat insulation door and refrigerator with same

Info

Publication number: CN112629130B
Application number: CN202010144463.0A
Authority: CN
Inventors: 丹野洋平; 河井良二; 内田麻理; 岛崎幸治; 平子贵之
Original assignee: Hitachi Global Life Solutions Inc
Current assignee: Hitachi Global Life Solutions Inc
Priority date: 2019-10-08
Filing date: 2020-03-04
Publication date: 2022-10-14
Anticipated expiration: 2040-03-04
Also published as: JP2021060159A; CN112629130A; JP7499014B2

Abstract

The invention provides a heat insulation door capable of ensuring the rigidity and heat insulation of the door without using polyurethane foam and a refrigerator with the heat insulation door. The heat-insulating door (200) of the present invention comprises a front panel (201), a back panel (204) facing the front panel (201), and a pull-out guide rail (205) attached to the back panel (204), wherein the surface of the back panel (204) has a plurality of extending ribs (204 b, 204 c), the ribs (204 b, 204 c) have portions intersecting the surface of the back panel (204), the back panel (204) and the pull-out guide rail (205) are joined at positions where the ribs (204 b, 204 c) intersect, and a region surrounded by the front panel (201) and the back panel (204) forms a space.

Description

Heat insulation door and refrigerator with same

Technical Field

The present invention relates to a heat-insulating door and a refrigerator having the same.

Background

In a household refrigerator, there is a demand for energy saving performance and low price by saving electric power. Nowadays, a door of a refrigerator is filled with polyurethane foam for heat insulation between the inside and the outside of the refrigerator. The leakage of cold air from the inside of the refrigerator to the outside of the refrigerator is prevented by the urethane foam having high heat insulation.

Further, the polyurethane foam secures rigidity of the door by integrating a front panel and a back panel constituting the door. However, special jigs and processes are required to fill the interior of the door with polyurethane foam, to prevent the polyurethane from leaking to the exterior of the door, or to prevent the structural members of the door from being deformed by the foaming pressure of the polyurethane. Therefore, the special jig and the special process become a factor of increasing the cost of the refrigerator.

As a known example relating to a refrigerator not using a polyurethane foam, patent document 1 describes: "a vacuum heat insulating material is sandwiched substantially over the entire surface between the inner box and the outer box, and a heat insulating material such as polystyrene foam is provided on the inner space side of the throat member".

As a known example of a structure for securing rigidity of a refrigerator door, patent document 2 describes: "A metal reinforcing plate having a plate thickness of about 1.0 to 2.0mm is provided along the inner door panel.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-195009 (paragraphs 0014 and 0015, FIG. 3, etc.)

Patent document 2: japanese patent laid-open publication No. 2011-237118 (paragraphs 0043 to 0047, FIG. 6 and FIG. 7, etc.)

Disclosure of Invention

Problems to be solved by the invention

However, in order to contribute to cost reduction of the refrigerator, it is required to secure rigidity and heat insulation of the door in a structure in which the interior of the door does not use polyurethane foam.

In patent document 1, a vacuum heat insulating material or polystyrene foam is provided to ensure heat insulation without using polyurethane foam inside the box. Therefore, the cost may be increased by the material cost and the processing cost.

In patent document 2, rigidity of the door is improved by providing a reinforcement plate along the inner door panel. Further, the polyurethane foam is filled in the door, which may increase the cost due to the process cost.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a heat insulating door capable of ensuring rigidity and heat insulating property of the door without using urethane foam, and a refrigerator including the same.

Means for solving the problems

In order to solve the above problem, a heat-insulating door according to a first aspect of the present invention includes a front panel, a back panel facing the front panel, and a pull-out rail attached to the back panel, wherein a plurality of extending ribs are provided on a panel surface of the back panel, the ribs have portions intersecting on the panel surface of the back panel, the back panel and the pull-out rail are joined at positions where the ribs intersect, and a region surrounded by the front panel and the back panel forms a space.

A heat-insulating door according to a second aspect of the present invention includes a front panel, a back panel facing the front panel, and a pull-out rail attached to the back panel, wherein the back panel has a plurality of extending ribs on a panel surface thereof, the ribs have portions intersecting with the panel surface of the back panel, the back panel and the pull-out rail are joined to each other at positions where the ribs intersect with each other, a vacuum heat-insulating material is provided between the front panel and the back panel, and a region surrounded by the front panel and the back panel forms a space.

A heat-insulating door according to a third aspect of the present invention includes a front panel, a back panel facing the front panel, and a pull-out rail attached to the back panel, wherein the back panel has a plurality of extending ribs on a panel surface thereof, the ribs have portions intersecting with the panel surface of the back panel, the back panel and the pull-out rail are joined at positions where the ribs intersect with each other, a block-shaped heat insulator is provided between the front panel and the back panel, and a region surrounded by the front panel and the back panel forms a space.

A heat-insulating door according to a fourth aspect of the present invention includes a front panel, a back panel facing the front panel, and a pull-out rail attached to the back panel, wherein the back panel has a plurality of extending ribs on a panel surface thereof, the ribs have portions intersecting with the panel surface of the back panel, the back panel and the pull-out rail are joined at positions where the ribs intersect with each other, at least one or more flat plates arranged substantially parallel to the front panel are provided between the front panel and the back panel, and a space is formed in a region surrounded by the front panel and the back panel.

A refrigerator according to a fifth aspect of the present invention includes the insulated door according to any one of the first to fourth aspects of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a low-cost heat-insulating door maintaining heat insulation properties, and a refrigerator including the same.

Drawings

Fig. 1 is a front view of a refrigerator according to embodiment 1 of the present invention as viewed from the front.

Fig. 2 isbase:Sub>A sectional view of the ice-making chamber door of fig. 1 cut on the linebase:Sub>A-base:Sub>A.

Fig. 3 is a front view of an exemplary back plate as viewed from the front.

Fig. 4 is a front view of another example of the back plate as viewed from the front.

Fig. 5 is a sectional view of a door of a refrigerator according to embodiment 2 of the present invention.

Fig. 6 is a sectional view of a door of a refrigerator according to embodiment 3 of the present invention.

Description of the symbols

100-refrigerator, 103-ice making chamber door (insulated door), 200, 500, 600-door (insulated door), 201, 505, 605-front panel, 202, 503, 603-upper panel, 203, 504, 604-lower panel, 204, 300, 400, 508, 606-back panel, 204 a-back panel protrusion (back panel), 204b, 301, 302, 303, 304, 401, 402, 506, 607-longitudinal rib (rib, rib extending on the panel surface of the back panel), 204c, 305, 306, 403, 404, 507, 608-transverse rib (rib), 205-pull-out guide rail, 206, 501, 601-space, 208, 209, 210, 211, 212-flat panel, 307, 308, 309, 310, 405, 406, 407, 408-threaded joint (intersecting part), 502-vacuum insulation material, 602-insulation block (insulator).

Detailed Description

The invention relates to a heat insulation door and a refrigerator with the same, which is a technology for improving heat insulation performance and reducing cost.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

EXAMPLE 1

Fig. 1 is a front view of a refrigerator 100 according to embodiment 1 of the present invention as viewed from the front. In the drawings of fig. 1 and later, the horizontal direction is shown by the X-axis, the vertical direction is shown by the Y-axis, and the front-rear direction is shown by the Z-axis.

Refrigerator 100 includes a refrigerating compartment left door 101, a refrigerating compartment right door 102, an ice making compartment door 103, a quick freezing compartment door 104, a freezing compartment door 105, and a vegetable compartment door 106 at the front side of cabinet 100H.

The refrigerating room left door 101 is rotatable about the Y axis by hinges provided at the upper and lower left ends of the front. The refrigerating chamber right door 102 is rotatable about the Y axis by a hinge provided at the front right end up and down.

A pull-out guide rail extending in the front-rear direction (the direction toward the front and rear side of the paper surface in fig. 1) is provided in each of ice making chamber door 103, quick freezing chamber door 104, freezing chamber door 105, and vegetable chamber door 106. The doors (103, 104, 105, 106) are extractable in the Z direction (forward direction) via extraction guides.

In addition, a shelf for vertically dividing the inside of the refrigerator 100 is provided in a space covered by the cabinet 100H of the refrigerator. The casing 100H itself is provided with a pipe through which a cooling refrigerant flows, a cooling device, and the like.

Fig. 2 isbase:Sub>A left sectional view of door 200 of an example of refrigerator 100 according to embodiment 1, and showsbase:Sub>A sectional view of ice making chamber door 103 in fig. 1 cut along linebase:Sub>A-base:Sub>A.

The door 200 is provided with a front plate 201, an upper plate 202, a lower plate 203, a back plate 204, and a pull-out guide rail 205. The pull-out guide rail 205 is a guide rail for moving the door 200 in the front-rear direction (the left-right direction in fig. 2).

Although not shown in fig. 2, the door 200 has a left plate (the back side of the sheet of fig. 2) and a right plate (the front side of the sheet of fig. 2) parallel to the Y-Z plane. The front plate 201, the upper plate 202, the lower plate 203, the back plate 204, the left plate, and the right plate are joined together, and a space 206 is formed inside the plates. The space 206 is a space for thermally insulating the inside of the refrigerator 100 from the outside thereof. The front plate 201, the upper plate 202, the lower plate 203, the back plate 204, the left plate, and the right plate may be formed in an integrated shape. A backboard convex portion 204a protruding rearward is formed on the backboard 204.

The back plate 204 and the pull-out rail 205 are joined by tightening a coupling screw 207 on the back plate boss 204a. A fixing projection 204d is formed on the joining portion of the back plate 204 so as to extend in a forward protruding manner. A female screw for screwing the fixing screw 207 is screwed into the fixing boss 204d.

< Ribs (301-306, 401-404) >

A plate-shaped vertical rib 204b extending substantially in the Y direction (vertical direction) and a plate-shaped horizontal rib 204c extending substantially in the X direction (horizontal direction) are provided inside the plate convex portion 204a.

Fig. 3 is a front view of an example of the back plate 300 as viewed from the front of the back plate 204 (see fig. 2). Fig. 3 shows an example of arrangement of the

vertical ribs

301, 302, 303, 304 and the

horizontal ribs

305, 306 provided inside the back projection 204a shown in fig. 2.

In the back panel 300,

longitudinal ribs

301, 302, 303, 304 extending in the Y direction and

lateral ribs

305, 306 extending in the X direction are provided. The longitudinal ribs (301 to 304) and the

lateral ribs

305 and 306 intersect on the front surface of the back plate 300.

The

longitudinal ribs

301 and 304 and the lateral rib 305 are arranged to intersect at each position of the

screw engagement portions

307 and 310 of the pull-out rail 205 and the back plate 300. The

longitudinal ribs

302, 303 and the lateral rib 306 are arranged so as to intersect at each position of the threaded

engagement portions

308, 309 of the drawer rail 205 and the back plate 300.

The vertical ribs (301 to 304) intersect the

lateral ribs

305, 306, thereby improving the strength of the screwed

portions

307, 308, 309, 310. Further, as shown in fig. 3, when the vertical ribs (301 to 304) and the

horizontal ribs

305 and 306 are arranged substantially orthogonally to each other, the load applied to the back plate 300 is uniformly dispersed, and the rigidity is improved. Further, the vertical ribs (301 to 304) and the

horizontal ribs

305 and 306 are easy to design and manufacture.

Fig. 4 is a front view of another example of the back plate 400 of the back plate 204 (see fig. 2) as viewed from the front. Fig. 4 shows an example of the arrangement of the

vertical ribs

401 and 402 and the

horizontal ribs

403 and 404 provided inside the backboard convex portion 204a (see fig. 2).

The back panel 400 is provided with

longitudinal ribs

401 and 402 extending substantially obliquely to the Y direction and

lateral ribs

403 and 404 extending in the X direction. The

longitudinal ribs

401, 402 and the

lateral ribs

403, 404 intersect on the front surface of the back plate 400.

The vertical rib 401 and the horizontal rib 403 cross at a screwed portion 405, and the vertical rib 401 and the horizontal rib 404 cross at a screwed portion 406. Vertical rib 402 and horizontal rib 403 intersect at threaded joint 408, and vertical rib 402 and horizontal rib 404 intersect at threaded joint 407. That is, the

ribs

401, 402, 403, and 404 are disposed so as to pass through any two of the threaded portions 405 to 408 at two locations, respectively. Further, the

ribs

401, 402, 403, and 404 may be arranged so that at least one of the ribs passes through any of the three or more

screw engagement portions

401, 402, 403, and 404.

The

longitudinal ribs

401, 402 intersect the

transverse ribs

403, 404, and the strength of the screwed

portions

405, 406, 407, 408 is improved. In the back plate 400, the

ribs

401, 402, 403, and 404 pass through any one of the screw joints 405, 406, 407, and 408 at two points, so that the strength is increased and the number of ribs is reduced. Therefore, material cost is reduced, and productivity is improved, achieving cost reduction.

The pull-out guide rails 205 (see fig. 2), the threaded engagement portions 307 to 310 of the back plate 300 shown in fig. 3, and the threaded engagement portions 405 to 408 of the back plate 400 shown in fig. 4 are partially deformed by the weight of the food or the like in the box and the pull-out load of pulling out the food or the like toward the front plate 201 (see fig. 2).

By disposing ribs (301 to 306) on the front surface of the back plate 300 and ribs (401 to 404) on the front surface of the back plate 400 so as to intersect the threaded joints 307 to 310 shown in fig. 3 and the threaded joints 405 to 408 shown in fig. 4, the vicinity of the threaded joints 307 to 310 and 405 to 408 can be reinforced, respectively. Therefore, deformation and breakage of the threaded portions 307 to 310 and 405 to 408 can be suppressed.

Further, as shown in fig. 4, by arranging the ribs (401 to 404) so as to pass through a plurality of portions of the screwed portions 405 to 408 in consideration of the deformation distribution of the back plate 400, it is possible to effectively suppress deformation of the back plate 400 and the screwed portions 405 to 408, and to reduce the material cost of the ribs.

The vertical ribs 301 to 304, 401, 402 and the

horizontal ribs

305, 306, 403, 404 may be arranged at positions and directions other than the rib arrangement example shown in fig. 3 and 4.

The ribs (301 to 306, 401 to 404) may have any thickness and height (Z direction), and the ribs (301 to 306, 401 to 404) may be formed integrally with the back plate 204 (300, 400) by injection molding or the like, or the ribs (301 to 306, 401 to 404) may be joined to the surface of the back plate 204 (300, 400) by an adhesive or the like. The back plate 204 (300, 400) is not limited to a flat plate shape, and may have a concave-convex shape or a truss structure in order to increase rigidity. The method of joining the drawer guide 205 and the

back plates

204, 300, and 400 is not limited to screws, and may be joining by fitting, an adhesive, or the like.

Plates

208, 209, 210, 211, 212 (see FIG. 2)

The

flat plates

208, 209, 210, 211, and 212 may be disposed inside the space 206 shown in fig. 2 substantially parallel to the XY plane. By dividing the interior of the space 206 by the flat plates 208 to 212, convection of gas in the space 206 is suppressed, heat transfer is reduced, and heat insulation is improved. Further, by applying a material such as aluminum having a low emissivity to the flat plates 208 to 212, the heat conductivity is reduced while suppressing radiant heat, and the heat insulation is improved. For example, a film having a low emissivity such as an aluminum tape may be attached to the surfaces of the resin flat plates 208 to 212 to suppress radiant heat.

The flat plates 208 to 212 disposed in the space 206 have arbitrary plate thicknesses, heights (Y direction), and numbers, and the distances between the flat plates 208 to 212 may or may not be equal to each other.

In addition, a material having a low emissivity may not be used for all the flat plates 208 to 212, and the material of each plate may be different.

The gas inside the space 206 may be air, or may be filled with argon gas or carbon dioxide having low thermal conductivity. The thermal insulation of the door 200 is improved by introducing argon gas, carbon dioxide, or the like having low thermal conductivity.

Further, the inside of the space 206 may be in a vacuum state, which further improves the heat insulation property.

According to embodiment 1 described above, no urethane foam is used inside the door (103, 200). Therefore, special jigs and processes are not required for preventing the polyurethane from leaking to the outside of the door (103, 200) or for preventing the structural members of the door (103, 200) from being deformed by the foaming pressure of the polyurethane. As a result, the cost of the refrigerator 100 can be reduced.

In screw engagement portions 307 to 310, 405 to 408 between back plate 204 (300, 400) and pull-out rail 205 which partially receive a load in doors (103, 200) of refrigerator 100,

ribs

204b, 204c, (301 to 306), and 401 to 404 which intersect on the surface of back plate 204 (300, 400) are provided, and rigidity and strength of doors (103, 200) are ensured. The space between the back plate 204 (300, 400) of the door (103, 200) and the front plate 201 is a space as a whole, and the inside of the space 206 is filled with air, for example, to ensure thermal insulation.

The inside of the space 206 is filled with a gas having a lower thermal conductivity than that of polyurethane, or the space is evacuated to a low heat transfer rate, thereby further improving the thermal insulation property. Further, the heat transfer due to radiation may be reduced by surface treatment or the like of the inner surface of the door (103, 200).

Furthermore, according to the structure without using polyurethane foam, the adhesiveness of the polyurethane to the constituent members of the doors (103, 200) does not need to be considered, so that the appearance design such as the material and shape of the doors (103, 200) is also improved.

In addition, the interior of the door (103, 200) is used as a space as a whole, so that the weight of the door (103, 200) is reduced by the weight of the polyurethane foam. The present configuration can be applied to various structures having a heat insulating function in general, in addition to the refrigerator 100.

As described above, it is possible to provide a technique that contributes to cost reduction of refrigerator 100 while ensuring rigidity and heat insulation of doors (103, 200) with a structure that does not use urethane foam inside doors (103, 200).

EXAMPLE 2

Fig. 5 shows a sectional view of a door 500 of the refrigerator 100 according to embodiment 2 of the present invention.

The door 500 according to embodiment 2 has a vacuum heat insulating material 502 provided in an internal space 501.

The space 501 is formed by bonding and covering a front plate 505, an upper plate 503, a lower plate 504, a back plate 508, and a left plate (back side of the drawing sheet of fig. 5) and a right plate (front side of the drawing sheet of fig. 5) which are not shown.

Note that, in the door 500, a description of a portion having the same configuration and function as those in fig. 2, 3, and 4 of embodiment 1 described above is omitted.

The vacuum insulation material 502 is formed by, for example, laying glass wool in an outer film and evacuating the film. In the case where it is difficult to make the entire space 501 inside the door 500 vacuum, as shown in fig. 5, by partially providing the vacuum insulation material 502, the heat insulation property is improved as compared with the case where only air is present in the space. By providing the vacuum insulation material 502 in the space 501, convection and radiation of heat in the space 501 can be suppressed. Further, heat conduction is suppressed by replacing a part of the space 501 with air by the vacuum heat insulating material 502 having a higher heat insulating property.

In fig. 5, the vacuum insulation material 502 is shown in contact with the upper plate 503 and the lower plate 504, but may be in contact with plate-shaped vertical ribs 506, plate-shaped horizontal ribs 507, and a plate-shaped back plate 508 provided on the front plate 505 and the back plate 508, without being in contact with each other.

The flat plates 208 to 212 for suppressing convection and radiation described in fig. 2 may be used together with the vacuum insulation material 502. Further, the inner surface of the door 500 may be surface-treated to suppress heat conduction due to radiation.

EXAMPLE 3

Fig. 6 shows a sectional view of a door 600 of the refrigerator 100 according to embodiment 3 of the present invention.

In the door 600 of embodiment 3, an insulating block 602 is provided in the internal space 601.

The space 601 is formed by bonding and covering a front plate 605, an upper plate 603, a lower plate 604, a back plate 606, and a left plate (back side of the paper surface of fig. 6) and a right plate (front side of the paper surface of fig. 6) which are not shown.

A description of a portion of the door 600 having the same configuration and function as those of fig. 2, 3, and 4 of embodiment 1 described above is omitted.

The heat insulating block 602 is formed by molding polyurethane into a block shape, for example, and a material having a lower thermal conductivity than air is preferable. For example, polystyrene foam is mentioned in addition to polyurethane. It is needless to say that materials other than polyurethane and polystyrene foam can be used for the heat insulating block 602.

By providing the heat insulating block 602 in a part of the space 601, heat insulation is improved as compared with a case where only air is present inside the space 601. The rigidity of the door 600 is improved by disposing the heat insulating block 602 in contact with any one of the plates forming the space 601.

In fig. 6, the adiabatic block 602 is shown in contact with a part of the upper plate 603, the lower plate 604, the front plate 605, and the back plate 606, but may be in contact with the plate-shaped vertical rib 607 and the plate-shaped horizontal rib 608 instead of being in contact with each other.

The flat plates 208 to 212 for suppressing convection and radiation described in fig. 2 may be used together with the heat insulating block 602. Further, a plurality of heat insulating blocks 602 may be disposed in the space 601.

By employing the embodiments described above, the rigidity and the heat insulating property of the door (103, 200, 500, 600) can be secured with a structure in which no urethane foam is used inside the door (103, 200, 500, 600), and the cost reduction of the refrigerator 100 can be facilitated. The present configuration can be applied to various structures having a heat insulating function in general, in addition to the refrigerator 100.

Other embodiments

1. In embodiments 1 to 3, the example in which the configuration of the present invention is applied to ice making chamber door 103 has been described, but the configuration of the present invention may be applied to any one of refrigerating chamber left door 101, refrigerating chamber right door 102, quick freezing chamber door 104, freezing chamber door 105, and vegetable chamber door 106 other than ice making chamber door 103.

2. The vertical ribs 204b (301 to 304, 506, 607) of embodiment 1 are illustrated as extending in the vertical direction, but may be configured to extend in other directions. The vertical ribs 204b (301 to 304, 506, 607) extend in one direction, thereby increasing the rigidity of the door (103, 200, 500, 600) in that direction.

3. When the doors (103, 200, 500, and 600) described in embodiments 1 to 3 are applied to the refrigerator 100, the refrigerator 100 having the same operational effects as those of the doors (103, 200, 500, and 600) described above can be obtained.

4. The present invention is not limited to the above-described embodiments 1 to 3, and includes various modifications. For example, the above-described embodiments have been described in detail to facilitate understanding of the present invention, and are not necessarily limited to having all the structures described. Moreover, a part of the structure of one embodiment may be replaced with the structure of another embodiment, and the structure of another embodiment may be added to the structure of one embodiment. Further, addition, deletion, and replacement of another configuration can be performed on a part of the configurations of the embodiments.

Claims

1. An insulated door, characterized in that,

comprises a front plate, a back plate opposed to the front plate, and a pull-out guide rail attached to the back plate,

the plate surface of the back plate is provided with a plurality of extending ribs,

the rib has a crossing part on the plate surface of the back plate,

the back plate and the pull-out guide rail are engaged at positions where the ribs intersect,

the area surrounded by the front plate and the back plate forms a space,

the region surrounded by the front plate and the back plate is filled with argon gas or carbon dioxide, or is in a vacuum state,

the heat insulating door is not filled with polyurethane foam.

2. An insulated door, characterized in that,

the rib has a crossing part on the plate surface of the back plate,

the back plate is joined to the pull-out guide at a position where the ribs intersect,

a vacuum heat insulating material is provided between the front plate and the back plate,

the area surrounded by the front plate and the back plate forms a space,

the heat insulating door is not filled with polyurethane foam.

3. An insulated door, characterized in that,

the rib has a crossing part on the plate surface of the back plate,

a block-shaped heat insulator is provided between the front plate and the back plate,

the area surrounded by the front plate and the back plate forms a space,

the heat insulating door is not filled with polyurethane foam.

4. An insulated door, characterized in that,

the rib has a crossing part on the plate surface of the back plate,

at least one flat plate disposed substantially parallel to the front plate is provided between the front plate and the back plate,

the area surrounded by the front plate and the back plate forms a space,

the heat insulating door is not filled with polyurethane foam.

5. An insulated door according to any of claims 1-4,

the ribs are arranged substantially perpendicular to the plate surface of the back plate.

6. An insulated door according to any of claims 1 to 4,

the rib is disposed at a portion where the two or more back plates are joined to the pull-out rail.

7. An insulated door according to any of claims 1 to 4,

any one of the ribs extends in the vertical direction.

8. An insulated door according to any of claims 2-4,

the region surrounded by the front plate and the back plate is filled with argon gas or carbon dioxide gas or is in a vacuum state.

9. A refrigerator is characterized in that the refrigerator is provided with a refrigerator door,

an insulated door according to any of claims 1 to 8.