WO2021019639A1

WO2021019639A1 - Compressor and refrigeration cycle device

Info

Publication number: WO2021019639A1
Application number: PCT/JP2019/029634
Authority: WO
Inventors: 克也前田; 雅章上川; 伊藤　健
Original assignee: 三菱電機株式会社
Priority date: 2019-07-29
Filing date: 2019-07-29
Publication date: 2021-02-04

Abstract

This compressor (1) has a casing (11) having formed therein a suction port (70a) through which a refrigerant is suctioned, and a plate-like strainer (80) installed facing the suction port inside the casing.

Description

Compressor and refrigeration cycle equipment

The present invention relates to a compressor equipped with a strainer and a refrigeration cycle device.

Inside the casing of the compressor, a strainer is installed to remove foreign substances such as dust sucked into the casing together with the refrigerant (see Patent Document 1). The strainer of Patent Document 1 is formed in a tubular shape and is connected to a suction port formed in a casing. By removing foreign matter flowing into the casing from the suction port, the compression portion slides from damage caused by the foreign matter. It plays a role of protecting the surface and the motor part.

JP-A-2007-303319

In a compressor, a strainer is required to remove foreign matter, but installing a strainer causes pressure loss in the refrigerant. The pressure loss of the refrigerant causes a decrease in the performance of the compressor. In Patent Document 1, since the tubular strainer is connected to the suction port, the flow path of the refrigerant is narrowed from the inside of the casing to the inside of the strainer in a sense, so that the pressure loss is increased.

In Patent Document 1, in order to reduce the pressure loss while installing the strainer in the casing, the flow path of the strainer, that is, the diameter of the strainer may be increased. However, in Patent Document 1, the diameter of the strainer cannot be increased due to structural restrictions. In Patent Document 1, the end portion of the strainer opposite to the suction port is arranged so as to enter the inner space of the circumferential coil end of the motor. Therefore, if the diameter of the strainer is increased, there is a concern that it may interfere with the coil end of the motor or the like. Therefore, there is a problem that the diameter of the strainer cannot be increased and it is difficult to reduce the pressure loss.

The present invention has been made in view of these points, and an object of the present invention is to provide a compressor and a refrigeration cycle device capable of reducing an increase in pressure loss due to installation of a strainer.

The compressor according to the present invention has a casing in which a suction port for sucking the refrigerant is formed, and a flat plate-shaped strainer installed in the casing facing the suction port.

According to the present invention, by making the strainer flat, it is possible to avoid shrinkage of the flow path due to the installation of the strainer, and it is possible to reduce an increase in pressure loss.

FIG. 5 is a schematic cross-sectional view of the compressor according to the first embodiment. It is a figure which shows the cover casing of the compressor which concerns on Embodiment 1. FIG. It is a figure which shows the strainer of the compressor which concerns on Embodiment 1. FIG. It is a figure which shows the photograph of the strainer of the compressor which concerns on Embodiment 1. FIG. It is a figure which shows the strainer of the compressor which concerns on Embodiment 2. FIG. It is sectional drawing of the main part including the strainer of the compressor which concerns on Embodiment 3. FIG. It is sectional drawing of the main part including the strainer of the compressor which concerns on Embodiment 4. FIG. It is a figure which shows the refrigerant circuit of the refrigerating cycle apparatus which concerns on Embodiment 5.

Hereinafter, embodiments of the compressor according to the present invention will be described with reference to the drawings. The present invention is not limited by these embodiments. Further, in each drawing, the same or corresponding parts are designated by the same reference numerals, and the description thereof will be omitted or simplified as appropriate. In addition, the shape, size, arrangement, etc. of the configurations shown in each figure can be appropriately changed within the scope of the present invention.

Embodiment 1.
The compressor according to the first embodiment will be described with reference to FIGS. 1 to 4.
FIG. 1 is a schematic cross-sectional view of the compressor according to the first embodiment. FIG. 2 is a diagram showing a cover casing of the compressor according to the first embodiment.
The compressor 1 according to the first embodiment has a compressor main body 10 and an oil separator 20. The oil separator 20 is fastened to the casing 11 of the compressor main body 10 by bolts (not shown). Although the demista type oil separator is shown here, a cyclone type oil separator may be used. Further, the oil separator may not be provided in the compressor but may be provided in the refrigeration cycle apparatus.

As shown in FIG. 1, the compressor main body 10 is fixed to a tubular casing 11, a motor 12 housed in the casing 11, a screw shaft 13 rotationally driven by the motor 12, and a screw shaft 13. It is provided with a screw rotor 14 and a strainer 80.

The casing 11 has a motor casing 50 for accommodating the motor 12, a cover casing 60, and a suction casing 70. The suction casing 70 is formed with a suction port 70a in which a refrigerant suction pipe (not shown) is connected from the outside to suck the refrigerant. The casing 11 has a configuration in which these are sequentially arranged and fixed in the axial direction of the screw shaft 13.

The screw rotor 14 has a columnar shape, and a plurality of screw grooves 14a extending spirally from one end to the other end of the screw rotor 14 are formed on the outer peripheral surface. One end side of the screw rotor 14 is the suction side of the refrigerant gas, and the screw groove 14a communicates with the suction pressure side. The other end side of the screw rotor 14 is the discharge side of the refrigerant gas, and the screw groove 14a communicates with the discharge pressure side.

On the side surface of the screw rotor 14, a pair of gate rotors 15 arranged so as to be axisymmetric with respect to the screw shaft 13 are arranged. Further, a tubular slide valve 16 is arranged between the side surface of the casing 11 and the screw rotor 14.

The gate rotor 15 has a disk shape, and a plurality of tooth portions 15a are provided on the outer peripheral surface along the circumferential direction. The tooth portions 15a of the gate rotor 15 are arranged so as to mesh with the screw grooves 14a of the screw rotor 14. A compression chamber 19 for compressing the refrigerant is formed by a space surrounded by the screw groove 14a, the tooth portion 15a of the gate rotor 15, the inner peripheral surface of the casing 11, and the slide valve 16. Oil for lubricating the bearing 17 and sealing the compression chamber 19 flows into the compression chamber 19 together with the refrigerant. The refrigerant compressed in the compression chamber 19 flows into the oil separator 20 and is separated into the refrigerant and the oil in the oil separator 20.

The slide valve 16 is provided so as to be slidable in the axial direction of the screw rotor 14 along the outer peripheral surface of the screw rotor 14. An opening 16a is formed at the center of the slide valve 16 in the sliding direction. The slide valve 16 may be used for the purpose of mechanical capacity control, or may be used for the purpose of changing the discharge timing to change the internal volume.

The motor 12 has a stator 12a that is inscribed and fixed in the motor casing 50, and a motor rotor 12b that is arranged inside the stator 12a. The motor rotor 12b is fixed to the screw shaft 13 and is arranged on the same line as the screw rotor 14. The end of the screw shaft 13 on the side not fixed to the motor 12 is rotatably supported by the bearing 17, and the end on the side fixed to the motor 12 is rotatably supported by the bearing 18. .. The rotation speed of the motor 12 can be changed by driving the inverter, and the motor 12 is driven by the inverter. The motor 12 may be a motor 12 having a constant speed that rotates at a constant rotation speed.

The bearing 18 is housed in the cover casing 60. The cover casing 60 is connected to the motor casing 50 by bolting, and a sealing component (not shown) such as a gasket or an O-ring is arranged on the joint surface. The cover casing 60 and the casing 11 may be fixed by welding instead of bolting. When welding is used, sealing parts can be eliminated.

As shown in FIG. 2, a plurality of bolt holes 60a are formed in the cover casing 60. The strainer 80, which will be described later, is fixed to the cover casing 60 by bolting using the bolt holes 60a, and the suction casing 70 is also fixed by bolting.

Sealing parts (not shown) such as gaskets or O-rings are arranged on the joint surface between the cover casing 60 and the suction casing 70. The cover casing 60 and the suction casing 70 do not have to be fastened with bolts, but may be welded. When welding is used, sealing parts can be eliminated.

The suction casing 70 is formed with a suction port 70a into which the refrigerant is sucked. A refrigerant suction pipe (not shown) is connected to the suction port 70a from the outside, and the refrigerant is sucked into the casing 11.

A strainer 80 is installed in the casing 11 so as to face the suction port 70a. The strainer 80 catches foreign matter such as fine dust sucked into the casing 11 from the suction port 70a together with the refrigerant, and has a role of preventing seizure of the compression chamber 19 and wear of the sliding portion of the bearing 18. Have.

FIG. 3 is a diagram showing a strainer of the compressor according to the first embodiment. In FIG. 3, (a) is a side view and (b) is a front view. FIG. 4 is a diagram showing a photograph of the strainer of the compressor according to the first embodiment, and is a partially enlarged view.
As shown in FIG. 3, the strainer 80 is formed in a circular flat plate shape. The strainer 80 has two disc-shaped plates 81 having a plurality of holes 81a formed therein and a disc-shaped filter member 82, and the filter member 82 is sandwiched between the two disc-shaped plates 81. Has a configuration. The material of the plate 81 is preferably a metal plate such as SPCC (cold rolled steel plate) in consideration of workability, but may be a resin plate. The filter member 82 is made of a metal mesh. The metal mesh is constructed by weaving a metal wire into a mesh shape. The filter member 82 is not limited to this structure, and may be made of filter paper. The filter member 82 may be selected in consideration of the required filtration accuracy and strength.

When the plate 81 is made of metal, the plate 81 and the filter member 82 are fixed by welding the outer periphery. When the plate 81 is made of resin, the plate 81 and the filter member 82 are fixed by using an adhesive or the like.

The drilling of the plate 81 is preferably performed by punching or edging from the viewpoint of productivity and cost. The plurality of holes 81a formed in the plate 81 are classified into a flow path hole 81aa forming a flow path and a bolt hole 81ab for fixing the strainer 80 and the cover casing 60. In FIG. 3, the flow path hole 81aa is indicated by a white hole, and the bolt hole 81ab is indicated by a hatched hole.

It is desirable that the flow path hole 81aa and the bolt hole 81ab have the same diameter from the same viewpoint of productivity and cost. The size of these holes and the pitch between the holes are determined in consideration of the required flow path area, aperture ratio and strength. When the aperture ratio is increased, the flow path area is increased, but the strength is inevitably decreased. Therefore, the aperture ratio is preferably set to, for example, 30% to 80%, and by setting it within this range, it is possible to secure both the flow path area and the strength.

It is preferable that the pitches of the plurality of holes 81a are equal pitches or close to equal pitches from the viewpoint of productivity and cost. Further, it is preferable that the bolt holes 81ab are provided in the outer peripheral portion and the inner peripheral portion of the plate 81, respectively, because vibration due to pulsation can be reduced. In this example, six bolt holes 81ab are formed on the outer peripheral portion of the plate 81 at intervals in the circumferential direction, and three bolt holes 81ab are formed on the inner peripheral portion of the plate 81 at intervals in the circumferential direction. The configuration is shown, but the number is arbitrary.

Next, the operation of the flat plate strainer 80 configured as described above will be described.
First, as a comparative example, the strainer has conventionally been tubular. Therefore, it is necessary to make the diameter of the strainer smaller than the diameter of the peripheral coil end of the motor so that the strainer does not interfere with the motor, and the smaller flow path diameter causes an increase in pressure loss.

On the other hand, in the first embodiment, the strainer 80 has a flat plate shape, so that the portion of interference with other parts in the casing 11 can be reduced and the strainer 80 does not interfere with the motor 12. Therefore, the diameter of the strainer 80 can be set without being subject to structural restrictions due to the positional relationship with the motor 12. Therefore, the diameter of the strainer 80 can be set larger than the diameter of the coil end, and can be expanded to the diameter of the installation location of the strainer 80 in the casing 11. From a different point of view, this corresponds to avoiding the reduction of the flow path diameter due to the installation of the strainer 80 in the casing 11, and the increase in pressure loss can be reduced.

In addition, some conventional tubular strainers have a structure in which the side surface of the cylinder is composed of a filter member through which the refrigerant passes, and the bottom surface of the cylinder is closed with a plate. In the strainer having this configuration, the refrigerant flowing in from the suction port once collides with the bottom surface of the cylinder, and the refrigerant rebounded by the collision passes through the filter member on the side surface.

On the other hand, since the strainer 80 of the first embodiment has a plurality of holes 81a penetrating in the flow direction of the refrigerant, the pressure loss can be reduced as compared with the conventional configuration, which is preferable.

As described above, the compressor 1 of the first embodiment has a casing 11 in which a suction port 70a for sucking the refrigerant is formed, and a flat plate-shaped compressor 11 installed in the casing 11 facing the suction port 70a. It has a strainer 80 and. As described above, by using the flat plate strainer 80, it is possible to avoid the reduction of the flow path due to the installation of the strainer 80 in the casing 11. As a result, the increase in pressure loss can be reduced, and the performance of the compressor 1 can be improved.

In the first embodiment, since the outer diameter of the strainer 80 is larger than the diameter of the suction port 70a, an increase in pressure loss can be reduced as compared with the case where a strainer having the same outer diameter as the suction port 70a is used, and the performance can be improved. Can be planned.

In the first embodiment, the strainer 80 has two plates 81 having a plurality of holes 81a and a filter member 82, and the filter member 82 is sandwiched between the two plates 81. As described above, the flat plate strainer 80 can be composed of the two plates 81 and the filter member 82. Further, the plurality of holes 81a can be classified into a flow path hole 81aa forming a flow path and a bolt hole 81ab for fixing, and the flow path hole 81aa and the bolt hole 81ab are round holes and have the same diameter. Therefore, productivity can be improved and costs can be reduced.

A metal mesh can be used for the filter member 82. A metal plate can be used for the two plates 81 of the strainer 80, and the strainer 80 can be fixed to the filter member 82 by welding at the outer peripheral portion.

The casing 11 includes a motor casing 50 that houses the motor 12, a cover casing 60, and a suction casing 70 in which a suction port 70a is formed. The casing 11 has a configuration in which these are arranged and fixed in order in the axial direction of the motor 12, and the strainer 80 may be fixed to the cover casing 60.

Embodiment 2.
In the second embodiment, the configuration of the strainer 80 is different from that of the first embodiment. Other configurations are the same as or equivalent to those of the first embodiment. Hereinafter, the configuration in which the second embodiment is different from the first embodiment will be mainly described, and the configurations not described in the second embodiment are the same as those in the first embodiment.

If the filter member 82 of the strainer 80 is clogged with foreign matter, or if the so-called liquid back operation in which the liquid refrigerant returns to the compressor is performed intermittently or continuously, excessive pressure is locally applied to the filter member 82 to filter the filter. The member 82 may be damaged. In order to prevent the filter member 82 from being damaged, the strength of the filter member 82 may be increased, but in order to increase the strength, it is necessary to increase the wire diameter of the metal wire rod constituting the filter member 82, and the wire diameter of the metal wire rod must be increased. The thicker the filter, the coarser the filter. If the mesh of the filter becomes coarse, the filtration accuracy of the filter member 82 deteriorates and the strainer cannot fulfill its original role. That is, foreign matter to be filtered may flow into the compression chamber 19 to cause seizure of the screw rotor 14, or foreign matter may flow into the motor 12 to cause insulation failure of the motor 12.

Therefore, in the second embodiment, we propose a strainer that has both filtration accuracy and mesh strength.

FIG. 5 is a diagram showing a strainer of the compressor according to the second embodiment. In FIG. 5, (a) is a side view and (b) is a front view.
The strainer 80 of the second embodiment has a plurality of filter members 82. By having a plurality of filter members 82, it is possible to achieve both filtration accuracy and strength. In the example of FIG. 5, the fine-meshed filter member 82a is sandwiched between two coarse-meshed filter members 82b. The coarse-meshed filter member 82b has a higher strength than the fine-meshed filter member 82a because the wire diameter of the metal wire is larger. Here, one fine-meshed filter member 82a and two coarse-meshed filter members 82b are used, but the number of each is arbitrary. Since the cost of the coarse filter member 82b is higher than that of the fine filter member 82a, one coarse filter member 82b may be used for cost reduction.

As the configuration of the plurality of filter members 82, for example, a plurality of filter members having the same number of meshes may be combined. Further, filter members having different numbers of meshes, such as 120 meshes, 30 meshes and 20 meshes, may be combined. Further, when a plurality of coarse filter members 82b are used, it is preferable that the filter members 82b are arranged so that the positions of the meshes of the respective meshes are overlapped for the purpose of reducing pressure loss.

As described above, in the second embodiment, the same effect as that of the first embodiment can be obtained, and since the strainer 80 is configured to include a plurality of filter members 82, both filtration accuracy and strength can be achieved. The planned strainer 80 can be realized.

Embodiment 3.
The third embodiment differs from the first embodiment only in the fastening structure of the strainer 80 and the cover casing 60. Other configurations are the same as or equivalent to those of the first embodiment. Hereinafter, the configuration in which the third embodiment is different from the first embodiment will be mainly described, and the configurations not described in the third embodiment are the same as those in the first embodiment.

FIG. 6 is a schematic cross-sectional view of a main part including the strainer of the compressor according to the third embodiment.
Since the strainer 80 is thin, the flatness may not be good. If the flatness of the strainer 80 is not good, the joint surface between the strainer 80 and the cover casing 60 has a metal touch, so that a gap is generated in the joint surface between the strainer 80 and the cover casing 60, and minute dust is generated through this gap. There is a possibility that it will flow into the compression chamber 19. Depending on the type of compressor, there is a risk of failure even with minute dust.

Therefore, in the third embodiment, as shown in FIG. 6, the seal component 84 and the seal component 85 are provided on the joint surface between the strainer 80 and the cover casing 60. A gasket or an O-ring can be used for each of the sealing component 84 and the sealing component 85. By providing the sealing component on the joint surface between the strainer 80 and the cover casing 60 in this way, it is possible to prevent dust from flowing into the compression chamber 19.

As described above, in the third embodiment, the same effect as that of the first embodiment can be obtained, and the following effects can be obtained. That is, since the seal component 84 and the seal component 85 are provided on the joint surface between the strainer 80 and the cover casing 60, the inflow of dust from the joint surface between the strainer 80 and the cover casing 60 into the compression chamber 19 is reliably prevented. , Can provide a highly reliable compressor.

Embodiment 4.
In the fourth embodiment, the shape of the strainer 80 is different from that of the first embodiment. Other configurations are the same as or equivalent to those of the first embodiment. Hereinafter, the configuration in which the fourth embodiment is different from the first embodiment will be mainly described, and the configurations not described in the fourth embodiment are the same as those in the first embodiment.

FIG. 7 is a schematic cross-sectional view of a main part including the strainer of the compressor according to the fourth embodiment.
In the fourth embodiment, the strainer 80 has a structure divided into a plurality of parts. Specifically, the strainer 80 has a split strainer 86 on the inner diameter side and a split strainer 87 on the outer diameter side. The split strainer 86 is formed in a circular shape. The split strainer 87 is formed in an annular shape. The roughness of each of the filter members 82 of the split strainer 86 and the split strainer 87 may be the same or different.

By adopting the structure in which the strainer 80 is divided in this way, each divided strainer is reduced in weight and easy to handle, so that maintenance work can be simplified. Further, at the time of maintenance, the bolt 90 provided on the screw shaft 13 may be manually rotated with a tool such as a torque wrench. In this operation, it is necessary to remove the strainer 80, but in the case where the strainer 80 is not divided, it is necessary to first remove the suction casing 70 from the cover casing 60 and then remove the strainer 80. On the other hand, in the fourth embodiment, since the strainer 80 is divided, the divided strainer 86 on the inner diameter side is taken out of the suction casing 70 through the suction port 70a without removing the suction casing 70. Can be done. That is, the work on the bolt 90 becomes possible only by removing the split strainer 86 on the inner diameter side, and the maintainability is improved.

Further, as the outer diameter of the strainer 80 becomes larger, the number of strainers taken for one base material is reduced, and the cost may increase significantly. On the other hand, in the fourth embodiment, the strainer 80 has a divided structure, so that the number of strainers can be increased, which is effective in reducing the cost.

As described above, in the fourth embodiment, the same effect as that of the first embodiment can be obtained, and since the strainer 80 is divided into a plurality of structures, the maintenance work can be simplified and the cost can be reduced. it can.

Although each embodiment of the compressor of the present invention has been described above, the present invention is not limited to each of these embodiments, and each embodiment can be appropriately combined. For example, the second embodiment and the third embodiment may be combined, and the strainer 80 having a plurality of filter members 82 may be fastened to the cover casing 60 by using a seal component. Further, the third embodiment and the fourth embodiment are combined to form the strainer 80 having a divided structure as shown in FIG. 7, and the divided strainers 86 and the divided strainers 87 are fastened to the cover casing 60 by using seal parts. It may be configured. Further, the second embodiment and the fourth embodiment may be combined, and each of the split strainers 86 and the split strainers 87 shown in FIG. 7 may have a plurality of filter members 82.

Embodiment 5.
The fifth embodiment relates to a refrigeration cycle apparatus including the compressor according to any one of the first to fourth embodiments.

FIG. 8 is a diagram showing a refrigerant circuit of the refrigeration cycle device according to the fifth embodiment.
The refrigeration cycle device 100 includes a compressor 101, a condenser 102, an expansion valve 103 as a depressurizing device, and an evaporator 104. As the compressor 101, the compressor 1 according to any one of the first to fourth embodiments is used.

In the refrigeration cycle device 100 configured as described above, the compressor 101 sucks in the refrigerant, compresses it, and then discharges it. The gas refrigerant discharged from the compressor 101 flows into the condenser 102, exchanges heat with the air passing through the condenser 102, and flows out as a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flowing out of the condenser 102 is depressurized by the expansion valve 103 to become a low-pressure gas-liquid two-phase refrigerant, and flows into the evaporator 104. The low-pressure gas-liquid two-phase refrigerant that has flowed into the evaporator 104 exchanges heat with the air that passes through the evaporator 104 to become a low-pressure gas refrigerant, which is again sucked into the compressor 101.

The refrigerating cycle device 100 configured in this way can be improved in performance by providing the compressor 1 according to any one of the first to fourth embodiments.

The refrigerating cycle device 100 can be applied to an air conditioner, a refrigerator / freezer, and the like.

1 compressor, 10 compressor body, 11 casing, 12 motor, 12a stator, 12b motor rotor, 13 screw shaft, 14 screw rotor, 14a screw groove, 15 gate rotor, 15a teeth, 16 slide valve, 16a opening , 17 bearings, 18 bearings, 19 compression chambers, 20 oil separators, 50 motor casings, 60 cover casings, 60a bolt holes, 70 suction casings, 70a suction ports, 80 strainers, 81 plates, 81a holes, 81aa flow path holes, 81ab bolt hole, 82 filter member, 82a filter member, 82b filter member, 84 seal part, 85 seal part, 86 split strainer, 87 split strainer, 90 bolt, 100 refrigeration cycle device, 101 compressor, 102 condenser, 103 expansion Valve, 104 evaporator.

Claims

A casing with a suction port for sucking refrigerant,
A compressor having a flat plate-shaped strainer installed in the casing facing the suction port.
The compressor according to claim 1, wherein the outer diameter of the strainer is larger than the diameter of the suction port.
The compressor according to claim 1 or 2, wherein the strainer has two plates having a plurality of holes and a filter member, and the filter member is sandwiched between the two plates.
The compressor according to claim 3, wherein the plurality of holes have a flow path hole forming a flow path and a bolt hole for fixing.
The compressor according to claim 3 or 4, wherein the plurality of holes are round holes.
The compressor according to claim 5, which is subordinate to claim 4, wherein the flow path hole and the bolt hole have the same diameter.
The compressor according to any one of claims 3 to 6, wherein the filter member is made of a metal mesh.
The compressor according to any one of claims 3 to 7, wherein the two plates of the strainer are metal plates.
The compressor according to any one of claims 3 to 8, wherein the two plates are fixed to the filter member by welding at the outer peripheral portion.
The compressor according to any one of claims 3 to 9, wherein the strainer includes a plurality of the filter members.
The compressor according to claim 10, wherein the plurality of filter members include a fine-mesh filter member and a coarse-mesh filter member.
The compressor according to any one of claims 1 to 11, wherein the strainer is divided into a plurality of parts.
The compressor according to claim 12, wherein the mesh roughness of each strainer divided into the plurality of strainers is different.
The compressor according to claim 12 or 13, wherein the strainer is divided into two parts, an inner diameter side and an outer diameter side.
The casing has a motor casing for accommodating a motor, a cover casing, and a suction casing in which the suction port is formed, and these have a configuration in which they are sequentially arranged and fixed in the axial direction of the motor.
The compressor according to any one of claims 1 to 14, wherein the strainer is fixed to the cover casing.
The compressor according to claim 15, wherein the strainer is fixed to the cover casing via a sealing component.
A refrigeration cycle device provided with the compressor according to any one of claims 1 to 16.