EP4745405A1 - ROTARY COMPRESSOR AND COOLING DEVICE - Google Patents

Abstract

A rotary compressor includes: a casing; cylinders disposed inside the casing; pistons configured to eccentrically rotate inside the cylinders; a shaft connected to the pistons and including a cavity; a pipe disposed inside the cavity and apart from a wall of the cavity; an upper bearing disposed over the cylinders and configured to pivotally support the shaft; a lower bearing disposed below the cylinders and configured to pivotally support the shaft; a rear muffler disposed below the lower bearing; and a positive displacement pump attached to the rear muffler and configured to discharge oil into the pipe.

Description

TECHNICAL FIELD
• The present disclosure relates to a rotary compressor and a refrigeration apparatus including the rotary compressor. The rotary compressor compresses gas in a compression chamber formed in a cylinder by eccentrically rotating a roller in the cylinder. The rotary compressor generally includes vanes for partitioning the compression chamber. Types of the rotary compressor include a so-called rolling piston type in which the roller eccentrically rotates while a vane that is separate from the roller contacts the roller, a so-called swing type in which a vane formed integrally with the roller swings with the eccentric rotation of the roller, a so-called hinge vane type in which the roller eccentrically rotates while the tip of the vane is rotatably fitted in a recess on the outer peripheral surface of the roller, and the like.
BACKGROUND ART
• Patent Document 1 discloses a rotary compressor including a casing, a cylinder arranged in the casing, a piston for forming a suction compression chamber in the cylinder, a shaft connected to the piston, and an upper bearing arranged over the cylinder and configured to pivotally support the shaft. Patent Document 1 discloses that an oil sump space for storing oil is formed in the lower portion of the casing of the rotary compressor, and that a main oil supply path communicating with the oil sump space and allowing oil stored in the oil sump space to flow upward is formed in the shaft.
RELATED ART DOCUMENTS PATENT DOCUMENTS
• Patent Document 1: Japanese Laid-Open Patent Application No. 2015-197044
SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION
• In a rotary compressor, it is desirable that the oil supply state does not change depending on the oil level of the lubricating oil and the rotational speed of the rotary compressor.
• Provided is a rotary compressor including an oil supply structure in which the variation of the oil supply state is small even when the oil level of the lubricating oil and the rotational speed of the rotary compressor change.
MEANS FOR SOLVING THE PROBLEMS
• A rotary compressor according to a first aspect includes:
• a casing;
• cylinders disposed inside the casing;
• pistons configured to eccentrically rotate inside the cylinders;
• a shaft connected to the pistons and including a cavity;
• a pipe disposed inside the cavity and apart from a wall of the cavity;
• an upper bearing disposed over the cylinders and configured to pivotally support the shaft;
• a lower bearing disposed below the cylinders and configured to pivotally support the shaft;
• a rear muffler disposed below the lower bearing; and
• a positive displacement pump attached to the rear muffler and configured to discharge oil into the pipe.
• According to the rotary compressor of the first aspect, the influence of the oil level of lubricating oil and the rotational speed of the rotary compressor can be reduced.
• A rotary compressor according to a second aspect is the rotary compressor according to the first aspect, wherein a lower portion of the pipe is fixed to the shaft.
• According to the rotary compressor of the second aspect, the pipe can be integrally fixed to the shaft.
• A rotary compressor according to a third aspect is the rotary compressor according to the first or second aspect, wherein an upper portion of the pipe is fixed to the shaft.
• According to the rotary compressor of the third aspect, the pipe can be further firmly fixed to the shaft.
• A rotary compressor according to a fourth aspect is the rotary compressor according to any one of the first to third aspects, wherein the pipe includes a hole in the upper portion of the pipe, and a hydraulic diameter of the hole is equal to or greater than an inner diameter of the pipe.
• According to the rotary compressor of the fourth aspect, the lubricating oil can be supplied from the inside of the pipe to the outside through the hole without inhibiting the flow of the lubricating oil.
• A rotary compressor according to a fifth aspect is the rotary compressor according to the fourth aspect, wherein the hole is positioned higher than an upper bearing oil supply hole provided in the shaft.
• According to the rotary compressor of the fifth aspect, the lubricating oil can be stably supplied to the upper bearing.
• A rotary compressor according to a sixth aspect is the rotary compressor according to the second aspect, wherein the lower portion of the pipe is fixed to the shaft at a position shifted from the lower bearing in a vertical direction.
• According to the rotary compressor of the sixth aspect, deformation of the lower bearing caused by deformation of the lower portion of the pipe can be suppressed.
• A rotary compressor according to a seventh aspect is the rotary compressor according to the second aspect, wherein the pipe includes a flow path penetrating in a vertical direction at a portion fixed to the shaft.
• According to the rotary compressor of the seventh aspect, the lubricating oil returned through the pipe can be discharged.
• A rotary compressor according to an eighth aspect is the rotary compressor according to the seventh aspect, wherein a total cross-sectional area of flow paths, each of the flow paths being the flow path, is equal to or greater than each of a first cross-sectional area inside the pipe and a second cross-sectional area between the inside of the shaft and the pipe.
• According to the rotary compressor of the eighth aspect, the discharge of the lubricating oil can be further enhanced.
• A rotary compressor according to a ninth aspect is the rotary compressor according to the second aspect, wherein the upper portion of the pipe is provided at a distance from the shaft.
• According to the rotary compressor of the ninth aspect, the structure of the pipe can be simplified.
• A rotary compressor according to a tenth aspect is the rotary compressor according to the ninth aspect, wherein the upper portion of the pipe is positioned higher than an upper bearing oil supply hole provided in the shaft.
• According to the rotary compressor of the tenth aspect, lubricating oil can be stably supplied to an upper bearing.
• A rotary compressor according to an eleventh aspect is the rotary compressor according to the first aspect, wherein a hydraulic diameter in a first flow path between the inside of the shaft and the pipe is smaller than the hydraulic diameter inside the pipe.
• According to the rotary compressor of the eleventh aspect, a shortage of lubricating oil can be suppressed by suppressing free fall of the lubricating oil in the first flow path and filling the first flow path with the lubricating oil.
• A rotary compressor according to a twelfth aspect is a rotary compressor according to the first aspect, wherein the hydraulic diameter in a first flow path between inside of the shaft and the pipe is greater than the hydraulic diameter inside the pipe.
• According to the rotary compressor of the twelfth aspect, the lubricating oil can be efficiently supplied by suppressing the flow velocity of the lubricating oil in the first flow path.
• A rotary compressor according to a thirteenth aspect is the rotary compressor according to the first aspect, wherein the upper end of the pipe is provided below an upper bearing oil supply hole provided in the shaft.
• According to the rotary compressor of the thirteenth aspect, the length of the pipe can be shortened.
• A rotary compressor according to a fourteenth aspect is the rotary compressor according to the first aspect, wherein the rear muffler includes a wall portion projecting downward, and the positive displacement pump is fixed to the wall portion.
• According to the rotary compressor of the fourteenth aspect, the positive displacement pump can be stably fixed to the rear muffler.
• A rotary compressor according to a fifteenth aspect is the rotary compressor according to the fourteenth aspect, wherein the rear muffler includes in the wall portion, an opening that communicates with a lower space in the casing.
• According to the rotary compressor of the fifteenth aspect, lubricating oil can be stably discharged to the lower space.
• A rotary compressor according to a sixteenth aspect is the rotary compressor according to any one of the first to fifteenth aspects, wherein the positive displacement pump is a trochoid pump.
• According to the rotary compressor of the sixteenth aspect, the lubricating oil can be stably supplied to the pipe.
• A refrigeration apparatus according to a first aspect is a refrigeration apparatus including the rotary compressor according to any one of the first to sixteenth aspects.
• According to the refrigeration apparatus of the first aspect, the influence of the oil level of the lubricating oil and the rotational speed of the rotary compressor can be reduced in the rotary compressor.
BRIEF DESCRIPTION OF THE DRAWINGS
• [FIG. 1] FIG. 1 is a perspective view of a rotary compressor according to a first embodiment.
• [FIG. 2] FIG. 2 is a cross-sectional view of the rotary compressor according to the first embodiment.
• [FIG. 3] FIG. 3 is a cross-sectional view of the rotary compressor according to the first embodiment.
• [FIG. 4] FIG. 4 is an exploded perspective view of a positive displacement pump in the rotary compressor according to the first embodiment.
• [FIG. 5] FIG. 5 is a bottom plan view of a body of the positive displacement pump in the rotary compressor according to the first embodiment.
• [FIG. 6] FIG. 6 is a plan view of the body of the positive displacement pump in the rotary compressor according to the first embodiment.
• [FIG. 7] FIG. 7 is a perspective view illustrating how the positive displacement pump is installed in the rotary compressor according to the first embodiment.
• [FIG. 8] FIG. 8 is a plan view for explaining the operation of the positive displacement pump in the rotary compressor according to the first embodiment.
• [FIG. 9] FIG. 9 is a cross-sectional view illustrating the flow of the lubricating oil in the rotary compressor according to the first embodiment.
• [FIG. 10] FIG. 10 is a cross-sectional view illustrating a flow of the lubricating oil in a modified example of the rotary compressor according to the first embodiment.
• [FIG. 11] FIG. 11 is a perspective view of a pipe in the rotary compressor according to the first embodiment.
• [FIG. 12] FIG. 12 is a cross-sectional view of a rotary compressor according to a second embodiment.
• [FIG. 13] FIG. 13 is a cross-sectional view of a rotary compressor according to a third embodiment.
• [FIG. 14] FIG. 14 is a cross-sectional view of a rotary compressor according to a fourth embodiment.
• [FIG. 15] FIG. 15 is a perspective view of a pipe in the rotary compressor according to the fourth embodiment.
• [FIG. 16] FIG. 16 is a schematic view of a refrigeration apparatus including the rotary compressor according to the present embodiment.
DETAILED DESCRIPTION OF THE INVENTION <First embodiment>
• Specific examples of a rotary compressor of a first embodiment will be described in the following with reference to the drawings. It is to be noted that the present disclosure is not limited to these examples, but is indicated by the scope of the claims and is intended to include all changes within the meaning and scope of the claims.
• It should be noted that, with respect to descriptions in the description and drawings according to each embodiment, components having substantially the same or corresponding functional configurations may be given the same reference numerals, thereby omitting redundant descriptions. In order to facilitate understanding, the scale of each component in the drawings may be different from the actual scale.
• In directions such as parallel, right angle, orthogonal, horizontal, vertical, up and down, right and left, and front and back, a degree of deviation is allowed that does not impair the effect of the embodiment. The shape of the corner portion is not limited to a right angle and may be rounded. The terms parallel, right angle, orthogonal, horizontal, and vertical may include substantially parallel, substantially right angle, substantially orthogonal, substantially horizontal, and substantially vertical, respectively.
• For example, substantially parallel means that even when two lines or two surfaces are not completely parallel to each other, they can be treated as parallel to each other within a manufacturing permissible range. Similarly to substantially parallel, it is intended that each of the other substantially right angle, substantially orthogonal, substantially horizontal, and substantially vertical may be treated as right angle, orthogonal, horizontal, and vertical, respectively, as long as the positional relationship between the two lines or the two surfaces is within a manufacturing permissible range.
• The rotary compressor according to the first embodiment will be described. The rotary compressor according to the first embodiment includes a casing, a cylinder disposed inside the casing, a piston configured to eccentrically rotate inside the cylinder, and a shaft that is connected to the piston and includes a cavity inside. The piston generally includes a circular roller and a vane configured to partition a compression chamber. The rotary compressor according to the first embodiment also includes a pipe disposed inside the cavity apart from the wall of the cavity, an upper bearing disposed above the cylinder and configured to pivotally support the shaft, and a lower bearing disposed below the cylinder and configured to pivotally support the shaft. Furthermore, the rotary compressor according to the first embodiment includes a rear muffler disposed at a lower portion of the lower bearing, and a positive displacement pump mounted to the rear muffler to discharge oil into the pipe.
• FIG. 1 is a perspective view of a rotary compressor 1 as an example of the rotary compressor according to the first embodiment. FIGS. 2 and 3 are cross-sectional views of the rotary compressor 1 as an example of the rotary compressor according to the first embodiment. FIG. 3 is an enlarged cross-sectional view of a compression part 70 in the rotary compressor 1.
• For convenience of explanation, an imaginary three-dimensional coordinate system (XYZ orthogonal coordinate system) consisting of an X-axis, a Y-axis, and a Z-axis (XYZ axes) orthogonal to each other may be set in the drawings. For example, for a coordinate axis perpendicular to the sheet of the drawing, when a black circle is indicated in a circle of the coordinate axis, it indicates that the coordinate axis is directed toward a viewer with respect to the sheet of the drawing. When a cross mark is indicated in a circle of the coordinate axis, it indicates that the coordinate axis is directed toward the front in a direction away from the viewer with respect to the sheet of the drawing.
• However, the coordinate system is defined for the purpose of explanation and is not intended to limit the attitude of the rotary compressor or the like according to the present embodiment.
• In the following drawings, a shaft 81 of the rotary compressor 1 extends along the Z-axis, and a piston 61 and a piston 62 of the rotary compressor 1 rotate in a plane parallel to an XY-plane including the X-axis and the Y-axis.
• A view in which an object is viewed in the opposite direction of the Z-axis from a +Z side along a Z-axis direction is referred to as a plan view. A view in which the object is viewed in the opposite direction of the Z-axis from the +Z side along the Z-axis direction is referred to as a top view. A view in which the object is viewed in the direction of the Z-axis from a -Z side along the Z-axis direction is referred to as a bottom plan view. A view in which the object is viewed in the direction of the Z-axis from the -Z side along the Z-axis direction is referred to as a bottom view.
• The rotary compressor 1 compresses a refrigerant. The refrigerant used in the rotary compressor 1 is, for example, carbon dioxide. The refrigerant is not limited to carbon dioxide, but may be, for example, a fluorocarbon refrigerant, a hydrofluoroolefin refrigerant, or a hydrocarbon refrigerant. The rotary compressor 1 includes a compressor body 10 and an accumulator 20.
[Compressor body 10]
• The compressor body 10 includes a casing 11, a suction pipe 12, a discharge pipe 13, and a power terminal 15. The casing 11 also includes a plate 14 for installing the compressor body 10.
• The compressor body 10 includes a compression part 70 and an electric drive part 80 inside the casing 11. The electric drive part 80 rotates the shaft 81. The compression part 70 compresses the refrigerant supplied from the suction pipe 12. The refrigerant compressed in the compression part 70 is discharged from the discharge pipe 13 to the outside of the rotary compressor 1. The compression part 70 is included in a compression mechanism.
• The electric drive part 80 rotates the shaft 81. The shaft 81 is connected to each of the piston 61 and the piston 62. In the compression part 70, the shaft 81 rotated by the electric drive part 80 rotates each of the piston 61 and the piston 62. Each of the piston 61 and the piston 62 is eccentrically rotated when the shaft 81 rotates. By rotating each of the piston 61 and the piston 62, the refrigerant is compressed in the compression part 70. Each of the piston 61 and the piston 62 includes a cylindrical roller and a vane configured to partition a compression chamber. The shaft 81 is a hollow shaft including an internal space 81a. The shaft 81 is a shaft having a hollow interior. The pipe 85 is inserted into the internal space 81a. The pipe 85 is arranged at a distance from the inner wall forming the internal space 81a of the shaft 81.
• The shaft 81 includes a main shaft 82, an eccentric portion 83, an intermediate connection part 84, an eccentric portion 86, and a countershaft portion 87. In the shaft 81, the main shaft 82, the eccentric portion 83, the intermediate connection part 84, the eccentric portion 86, and the countershaft portion 87 are integrally formed.
• The main shaft 82 is tube-shaped or has a cylindrical shape. The upper end of the main shaft 82 is connected to a motor rotor in the electric drive part 80. The lower end of the main shaft 82 is rotatably supported by an upper bearing 32. The lower end of the main shaft 82 is included in a journal.
• The eccentric portion 83 is a cylindrical portion having a diameter greater than that of the main shaft 82. The central axis of the eccentric portion 83 is eccentric from the central axis of the main shaft 82. The piston 62 is attached to the eccentric portion 83.
• The intermediate connection part 84 connects the eccentric portion 83 and the eccentric portion 86.
• The eccentric portion 86 is a cylindrical portion having a diameter greater than that of the main shaft 82. The central axis of the eccentric portion 86 is eccentric from the central axis of the main shaft 82. The eccentric portion 86 is eccentric to the central axis of the main shaft 82 on the side opposite to the eccentric portion 83. The piston 61 is attached to the eccentric portion 86. The lower surface of the eccentric portion 86 slides on the upper surface of a lower bearing 31.
• The countershaft portion 87 is tube-shaped or has a cylindrical shape. The countershaft portion 87 is rotatably supported by the lower bearing 31. The countershaft portion 87 is included in a journal.
• The compression part 70 includes the lower bearing 31, a cylinder 41, a middle plate 33, a cylinder 42, and an upper bearing 32. The lower bearing 31, the cylinder 41, the middle plate 33, the cylinder 42, and the upper bearing 32 are stacked in order from the bottom. The upper bearing 32 is disposed over the cylinder 41 and the cylinder 42. The lower bearing 31 is disposed below the cylinder 41 and the cylinder 42. The shaft 81 penetrates through each of the lower bearing 31, the cylinder 41, the middle plate 33, the cylinder 42, and the upper bearing 32. Each of the lower bearing 31, the cylinder 41, the middle plate 33, the cylinder 42, and the upper bearing 32 is provided with an oil supply hole through which a lubricating oil is supplied to a part through which the shaft 81 penetrates. Furthermore, the shaft 81 includes a communication hole penetrating from the internal space 81a to the outside of the shaft 81 in order to supply the lubricating oil to each of the lower bearing 31, the cylinder 41, the cylinder 42, and the upper bearing 32. Specifically, the shaft 81 includes a lower-bearing oil supply hole 81h1, a communication hole 81h2, a communication hole 81h3, and an upper-bearing oil supply hole 81h4 in order to supply the lubricating oil to the lower bearing 31, the cylinder 41, the cylinder 42, and the upper bearing 32. The shaft 81 may be provided with a communication hole for supplying the lubricating oil to the middle plate 33.
• The compression part 70 includes the piston 61 configured to be eccentrically rotated by the shaft 81 in the cylinder 41. The lower surface of the piston 61 slides on the upper surface of the lower bearing 31. The upper surface of the piston 61 slides on the lower surface of the middle plate 33.
• The compression part 70 is provided with the piston 62 eccentrically rotated by the shaft 81, inside the cylinder 42. The lower surface of the piston 62 slides on the upper surface of the middle plate 33. The upper surface of the piston 62 slides on the lower surface of the upper bearing 32.
• The compression part 70 is provided with a rear muffler 34 arranged below the lower bearing 31. Furthermore, the compression part 70 is provided with a positive displacement pump 50 attached to the rear muffler 34.
(Positive displacement pump 50)
• The positive displacement pump 50 will be described in detail. FIG. 4 is an exploded perspective view of the positive displacement pump 50 in the rotary compressor 1, which is an example of the rotary compressor according to the first embodiment.
• The positive displacement pump 50 discharges lubricating oil into the internal space 81a of the shaft 81. More specifically, the positive displacement pump 50 discharges the lubricating oil into the pipe 85. The positive displacement pump 50 is a trochoid pump. In the rotary compressor according to the first embodiment, the positive displacement pump is not limited to the trochoid pump, and may be, for example, a gear pump, a vane pump, or a piston pump.
• The positive displacement pump 50 is attached to the rear muffler 34. The positive displacement pump 50 includes a body 51, an outer rotor 52, an inner rotor 53, and a thrust plate 54.
(Body 51)
• The body 51 will be described in detail. FIG. 5 is a bottom plan view of the body 51 of the positive displacement pump 50 in the rotary compressor 1, which is an example of the rotary compressor according to the first embodiment. FIG. 6 is a plan view of the body 51 of the positive displacement pump 50 in the rotary compressor 1, which is an example of the rotary compressor according to the first embodiment.
• The body 51 includes a recess 51g in which the outer rotor 52 and the inner rotor 53 are accommodated. The body 51 includes a through hole 51s that penetrates through the body 51 from a bottom surface 51D, which is the lowermost surface of the body 51, to a bottom surface 51S in the recess 51g. The positive displacement pump 50 sucks the lubricating oil accumulated in an oil sump SP (lower space) through the through hole 51s.
• A groove 51d is formed in the bottom surface 51S of a recess 51g of the body 51.
• The body 51 includes a plurality of flange portions 51f extending in a direction parallel to the XY-plane, in the upper portion. Each of the plurality of flange portions 51f includes a through hole 51h through which a bolt 55 penetrates. An outer surface 51T, which is a part of a cylindrical surface, is formed in the portion where each flange portion 51f is formed.
(Outer rotor 52)
• The outer rotor 52 is fixed to the recess 51g in the body 51. The outer rotor 52 includes a through hole 52h at its center into which the inner rotor 53 is inserted. An inner surface 52S of the through hole 52h includes trochoidal curves in cross section.
(Inner rotor 53)
• The inner rotor 53 is inserted into the through hole 52h of the outer rotor 52. The inner rotor 53 is rotatable inside the through hole 52h of the outer rotor 52. An outer surface 53S of the inner rotor 53 includes trochoidal curves in cross section. The number of teeth of the inner rotor 53 is one less than the number of teeth of the outer rotor 52. The inner rotor 53 includes a through hole 53h at its center.
(Thrust plate 54)
• The thrust plate 54 is a plate configured to hold down the inner rotor 53. The thrust plate 54 includes a through hole 54h at its center.
• The mounting of the positive displacement pump 50 to the rear muffler 34 will be described. FIG. 7 is a perspective view illustrating how the positive displacement pump 50 is installed in the rotary compressor 1, which is an example of the rotary compressor according to the first embodiment.
• The rear muffler 34 includes a flat plate portion 34a that extends in the X-axis direction and the Y-axis direction, and a wall portion 34b that extends from the flat plate portion 34a along the Y-axis direction (vertical direction) and in a direction opposite to the Z-axis. The wall portion 34b includes an inner surface 34S. The wall portion 34b projects downward from the flat plate portion 34a.
• The positive displacement pump 50 is fitted to the wall portion 34b. Specifically, the outer surface 51T of the body 51 of the positive displacement pump 50 is fitted to the inner surface 34S of the wall portion 34b, whereby the positive displacement pump 50 is fitted to the wall portion 34b. The positive displacement pump 50 may be fitted to the rear muffler 34 by press-fitting.
• The wall portion 34b includes a plurality of screw holes 34s into which the bolts 55 are inserted. Each bolt 55 penetrates through the through hole 51h in the flange portion 51f and is screwed into the screw hole 34s in the wall portion 34b. By screwing the bolt 55 into the screw hole 34s, the flange portion 51f is fixed to the wall portion 34b by the bolt 55. By fixing the flange portion 51f to the wall portion 34b by the bolt 55, the positive displacement pump 50 is fixed to the rear muffler 34.
• A space is formed in a portion of the wall portion 34b where the inner surface 34S and the outer surface 51T are not in contact with each other. The lubricating oil discharged into the internal space 81a of the shaft 81 is discharged into the oil sump SP through the space.
• Next, the operation of the positive displacement pump 50 will be described. FIG. 8 is a plan view for explaining the operation of the positive displacement pump 50 in the rotary compressor 1, which is an example of the rotary compressor according to the first embodiment. More specifically, FIG. 8 is a plan view illustrating a top view of the outer rotor 52 and the inner rotor 53 in the positive displacement pump 50. When the inner rotor 53 rotates in the direction of an arrowed line R with respect to the outer rotor 52, the lubricating oil accumulated in the oil sump SP is sucked in a range DS. The through hole 51s is connected to the range DS. Then, the lubricating oil is discharged in a range DE. The lubricating oil is discharged downward once and then discharged by passing through the through hole 53h of the inner rotor 53 via the groove 51d.
• As described above, when the inner rotor 53 rotates with respect to the outer rotor 52, the lubricating oil is sucked in from the through hole 51s of the body 51. The sucked lubricating oil is transferred as the outer rotor 52 rotates. The transferred lubricating oil is discharged into the internal space 81a of the shaft 81 through the through hole 53h of the inner rotor 53.
• The flow of the lubricating oil will be described in detail. FIG. 9 is a cross-sectional view for illustrating the flow of the lubricating oil in the rotary compressor 1, which is an example of the rotary compressor according to the first embodiment. The lubricating oil accumulated in the oil sump SP is sucked from the through hole 51s as indicated by an arrowed dotted line SC. The sucked lubricating oil is transferred by the rotation of the inner rotor 53 relative to the outer rotor 52. Then, as indicated by an arrowed dotted line DC, the transferred lubricating oil is discharged to the inside of the pipe 85 through the groove 51d and to the internal space 81a of the shaft 81.
• The lubricating oil discharged into the pipe 85 of the shaft 81 passes through the inside of the pipe 85 and is supplied between the internal space 81a and the pipe 85 as shown by an arrowed dotted line in FIG. 3. The lubricating oil supplied between the internal space 81a and the pipe 85 is supplied to the lower bearing 31, the cylinder 41, the cylinder 42, and the upper bearing 32 through the lower-bearing oil supply hole 81h1, the communication hole 81h2, the communication hole 81h3, and the upper-bearing oil supply hole 81h4, respectively.
• In addition, among the lubricating oil supplied between the internal space 81a and the pipe 85, the lubricating oil remaining without being supplied to the lower bearing 31, the cylinder 41, the cylinder 42, and the upper bearing 32 is discharged from the internal space 81a of the shaft 81. More specifically, the lubricating oil is discharged from a flow path (first flow path) between the internal space 81a and the pipe 85. The lubricating oil discharged from the internal space 81a of the shaft 81 is discharged into the oil sump SP through a space between the rear muffler 34 and the positive displacement pump 50 along an arrowed dotted line DR shown in FIG. 9.
• The method of discharging the lubricating oil discharged from the internal space 81a of the shaft 81 into the oil sump SP is not limited to the above example. FIG. 10 is a cross-sectional view illustrating a flow of the lubricating oil in a modified example of the rotary compressor 1, which is an example of the rotary compressor according to the first embodiment. The modified example includes a rear muffler 134 instead of the rear muffler 34. The rear muffler 134 includes an opening 134h in a wall portion 134b communicating with the outside of the wall portion 134b for discharging the lubricating oil to the oil sump SP. As illustrated by the arrowed dotted line DR in FIG. 10, the lubricating oil may be discharged to the oil sump SP through the opening 134h.
• When the rear muffler includes the opening, there is no need to provide a space between the rear muffler and the positive displacement pump as in the case of the rotary compressor 1.
• Furthermore, as illustrated in FIGS. 9 and 10, a lower end 81e of the shaft 81 may be disposed at a distance from the thrust plate 54. The lower end 81e of the shaft 81 and the thrust plate 54 are separated by a distance h.
• In order to rotate the inner rotor 53, a lower portion of the pipe 85 may be fixed to the inner rotor 53. Furthermore, in order to rotate the inner rotor 53, the lower portion of the shaft 81 may be fixed to the inner rotor 53.
• The pipe 85 will be described. FIG. 11 is a perspective view of a pipe 85 in a rotary compressor 1, which is an example of the rotary compressor according to the first embodiment. The pipe 85 includes a pipe 85p and a flange portion 85f.
• The pipe 85p is disposed in the internal space 81a at a distance from a wall (cavity wall) forming the internal space 81a of the shaft 81. An upper portion of the pipe 85p is inserted and fixed in a hole provided in the shaft 81. The flange portion 85f is provided at the lower portion of the pipe 85. The lower portion of the pipe 85p is fixed to the inner wall of the flange portion 85f by press-fitting. The lower end of the pipe 85p may include a space toward the step of the inner wall or may contact the step of the inner wall. The flange portion 85f is fixed to the shaft 81. In other words, the pipe 85 has a double-support structure in the shaft 81. Thus, the pipe 85 is firmly fixed, and the influence of vibration can be suppressed. The flange portion 85f is fixed to the shaft 81 at a position vertically displaced from the lower bearing 31. Thus, when the positive displacement pump 50 is fixed by fitting or press-fitting, deformation of a bearing portion of the lower bearing 31 can be suppressed.
• The pipe 85p includes a hole 85ph. The hole 85ph is located above the oil supply hole (upper-bearing oil supply hole 81h4) provided in the upper bearing 32. Since the hole 85ph is located above the oil supply hole (upper-bearing oil supply hole 81h4) provided in the upper bearing 32, oil can be supplied to a portion of the upper bearing 32. The hydraulic diameter of the hole 85ph may be greater than the inner diameter of the pipe 85p. Since the hydraulic diameter of the hole 85ph is equal to or greater than the inner diameter of the pipe 85p, the flow of the lubricating oil flowing through the pipe 85p can be prevented from being obstructed by the hole 85ph.
• The number of holes 85ph is not limited to one, but may be plural. When a plurality of holes 85ph are provided, the hydraulic diameter described above is the sum of the diameters of the plurality of holes 85ph.
• Furthermore, the hydraulic diameter in the flow path (first flow path) between the internal space 81a of the shaft 81 and the pipe 85p may be smaller than the hydraulic diameter in the pipe 85p. By making the hydraulic diameter in the first flow path smaller than the hydraulic diameter in the pipe 85p, the flow of the lubricating oil in the first flow path is restrained, such that insufficient oil supply due to free fall of the lubricating oil can be prevented and oil supply can be ensured.
• The hydraulic diameter in the flow path (first flow path) between the internal space 81a of the shaft 81 and the pipe 85p may be greater than the hydraulic diameter in the pipe 85p. By making the hydraulic diameter in the first flow path greater than the hydraulic diameter in the pipe 85p, the flow velocity in the pipe in the first flow path is reduced, such that the oil can be efficiently supplied to each oil supply hole.
• The pipe 85p includes the hole 85ph. The hydraulic diameter of the hole 85ph may be equal to or greater than the inner diameter of the pipe 85p. When the hydraulic diameter of the hole 85ph is equal to or greater than the inner diameter of the pipe 85p, the flow of the lubricating oil flowing through the pipe 85p can be prevented from being obstructed by the hole 85ph.
• The flange portion 85f is provided with a cutout portion 85fh that forms a vertically penetrating flow path through which the lubricating oil flows when the pipe 85 is fixed to the lower portion of the shaft 81. The lubricating oil returns to the positive displacement pump 50 through the cutout portion 85fh. The total cross-sectional area of the flow path formed by the cutout portion 85fh is equal to or greater than each of the cross-sectional area inside the pipe 85p (the first cross-sectional area) and the cross-sectional area between the inside of the shaft 81 and the pipe 85p (the second cross-sectional area). The discharge of the lubricating oil can be promoted by making the total cross-sectional area of the flow path formed by the cutout portion 85fh equal to or greater than each of the first cross-sectional area and the second cross-sectional area.
• The rotary compressor according to the first embodiment is provided with the positive displacement pump, such that oil can be supplied without being restricted by the oil level of the lubricating oil and the rotational speed of the rotary compressor.
<Second embodiment>
• A rotary compressor according to a second embodiment will be described. The rotary compressor according to the second embodiment includes a different pipe from the rotary compressor according to the first embodiment. In the rotary compressor according to the second embodiment, the pipe has a cantilever structure.
• FIG. 12 is a cross-sectional view of the rotary compressor according to the second embodiment. In the rotary compressor according to the second embodiment, a pipe 185 is provided instead of the pipe 85 in the rotary compressor 1. The pipe 185 includes a pipe 185p and a flange portion 185f. The pipe 185p is disposed in the internal space 81a at a distance from a wall (cavity wall) forming the internal space 81a of the shaft 81. An upper portion of the pipe 185p is provided at a distance from the shaft 81. The flange portion 185f is provided at a lower portion of the pipe 185. The flange portion 185f is fixed to the shaft 81. That is, the pipe 185 has a cantilever structure in the shaft 81. As illustrated in FIG. 12, the upper portion of the pipe 185 need not necessarily be fixed to the shaft 81. In other words, the upper portion of the pipe 185 may be provided apart from the shaft 81. The upper end of the pipe 185 is located above the oil supply hole (upper-bearing oil supply hole 81h4) provided in the upper bearing 32.
• A rotary compressor according to the second embodiment has the same effect as the rotary compressor according to the first embodiment. In the rotary compressor according to the second embodiment, since the upper portion of the pipe is not fixed, the manufacturing cost can be reduced.
<Third embodiment>
• A rotary compressor according to a third embodiment will be described. The rotary compressor according to the third embodiment includes a different pipe from the rotary compressor according to the first embodiment. In the rotary compressor according to the third embodiment, the pipe has a cantilever structure.
• FIG. 13 is a cross-sectional view of the rotary compressor according to the third embodiment. The rotary compressor according to the third embodiment includes a pipe 285 in place of the pipe 85 in the rotary compressor 1. The pipe 285 includes a pipe 285p and a flange portion 285f. The pipe 285p is disposed in the internal space 81a at a distance from a wall (cavity wall) forming the internal space 81a of the shaft 81. An upper portion of the pipe 285p is provided at a distance from the shaft 81. The flange portion 285f is provided at a lower portion of the pipe 285. The flange portion 285f is fixed to the shaft 81. That is, the pipe 285 has a cantilever structure in the shaft 81. The pipe 285 is shorter than the pipe 185. The lubricating oil can be supplied by spraying the lubricating oil from the pipe 285.
• The rotary compressor according to the third embodiment has the same effect as the rotary compressor according to the second embodiment. The rotary compressor according to the third embodiment can suppress the influence of vibration because the length of the pipe is short.
<Fourth embodiment>
• A rotary compressor according to a fourth embodiment will be described. The rotary compressor according to the fourth embodiment includes a different pipe from the rotary compressor according to the first embodiment. In the rotary compressor according to the fourth embodiment, the upper portion of the pipe in the rotary compressor according to the second embodiment is fixed by an elastic member.
• FIG. 14 is a cross-sectional view of the rotary compressor according to the fourth embodiment. FIG. 15 is a perspective view of a pipe 385 as an example of a pipe in the rotary compressor according to the fourth embodiment. The pipe 385 includes a pipe 385p, a flange portion 385f, and an elastic member 386. The pipe 385p includes a hole 385ph. The flange portion 385f is provided with a cutout portion 385fh which serves as a flow path through which lubricating oil flows vertically when the pipe 385 is fixed to the lower portion of the shaft 81. In the rotary compressor according to the fourth embodiment, the pipe 385 is provided in place of the pipe 85 in the rotary compressor 1. As illustrated in FIG. 14, an upper portion of the pipe 385 is fixed to the shaft 81 by the elastic member 386. The hole 385ph in the pipe 385 is located above the oil supply hole (upper-bearing oil supply hole 81h4) provided in the upper bearing 32.
• The rotary compressor according to the fourth embodiment has the same effect as the rotary compressor according to the second embodiment. In the rotary compressor according to the fourth embodiment, since the upper portion of the pipe is fixed by the elastic member, the influence of vibration can be suppressed.
<Refrigeration apparatus>
• A refrigeration apparatus including the rotary compressor according to the present embodiment will be described. FIG. 16 is a schematic view of a refrigeration apparatus 100 as an example of the refrigeration apparatus including the rotary compressor according to the present embodiment.
• The refrigeration apparatus 100 includes a compressor 101, a four-way valve 102, a heat exchanger 103, an expansion valve 104, and a heat exchanger 105. The compressor 101 is the rotary compressor according to the present embodiment.
• First, a case where cooling is performed by the heat exchanger 105 in the refrigeration apparatus 100 will be described. FIG. 15 is a diagram illustrating a connection of a case where cooling is performed by the heat exchanger 105 in the refrigeration apparatus 100.
• The refrigerant compressed by the compressor 101 is supplied to the heat exchanger 103 through the four-way valve 102. The refrigerant supplied to the heat exchanger 103 is cooled by heat exchange with the air or the like in the heat exchanger 103. The refrigerant cooled by the heat exchanger 103 is condensed and liquefied, and supplied to the expansion valve 104. The refrigerant is depressurized by the expansion valve 104. The depressurized refrigerant is supplied to the heat exchanger 105. In the heat exchanger 105, the refrigerant evaporates and vaporizes. Then, the refrigerant discharged from the heat exchanger 105 returns to the compressor 101 again and is compressed. The refrigeration apparatus 100 cools an object by the heat of vaporization caused by the evaporation of the refrigerant in the heat exchanger 105.
• Next, a case of heating by the heat exchanger 105 in the refrigeration apparatus 100 will be described. The refrigerant compressed by the compressor 101 is supplied to the heat exchanger 105 through the four-way valve 102. In the heat exchanger 105, through the supply of the compressed refrigerant at high temperature, the refrigeration apparatus 100 heats the object. The refrigerant heat-exchanged in the heat exchanger 105 is condensed and liquefied, and supplied to the expansion valve 104. The refrigerant is depressurized by the expansion valve 104. The depressurized refrigerant is supplied to the heat exchanger 103. The refrigerant is vaporized by heat exchange with the air or the like in the heat exchanger 103. Then, the refrigerant discharged from the heat exchanger 103 passes through the four-way valve 102 and returns to the compressor 101 again to be compressed.
• Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Various modifications and enhancements are possible, such as combinations or substitutions with parts or all of other embodiments.
• This application claims priority to Basic Patent Application No. 2024-162420, filed in the Japanese Patent Office on September 19, 2024, the entire contents of which are hereby incorporated by reference.
REFERENCE SIGNS LIST

1

Rotary compressor

10

Compressor body

11

Casing

31

Lower bearing

32

Upper bearing

34

Rear muffler

41, 42

Cylinder

50

Positive displacement pump

52

Outer rotor

53

Inner rotor

54

Thrust plate

61, 62

Piston

70

Compression part

80

Electric drive part

81

Shaft

81a

Internal space

85

Pipe

100

Refrigeration apparatus

101

Compressor

103, 105

Heat exchanger

104

Expansion valve

Claims (17)

1. A rotary compressor (1), comprising:

   a casing (11);

   cylinders (41 and 42) disposed inside the casing (11);

   pistons (61 and 62) configured to eccentrically rotate inside the cylinders (41 and 42);

   a shaft (81) connected to the pistons (61 and 62) and including a cavity (81a);

   a pipe (85, 185, 285, or 385) disposed inside the cavity (81a) and apart from a wall of the cavity (81a);

   an upper bearing (32) disposed over the cylinders (41 and 42) and configured to pivotally support the shaft (81);

   a lower bearing (31) disposed below the cylinders (41 and 42) and configured to pivotally support the shaft (81);

   a rear muffler (34) disposed below the lower bearing (31); and

   a positive displacement pump (50) attached to the rear muffler (34) and configured to discharge oil into the pipe (85, 185, 285, or 385).
2. The rotary compressor (1) according to claim 1, wherein
   a lower portion of the pipe (85, 185, 285, or 385) is fixed to the shaft (81).
3. The rotary compressor (1) according to claim 1 or claim 2, wherein
   an upper portion of the pipe (85 or 385) is fixed to the shaft (81).
4. The rotary compressor (1) according to any one of claims 1 to 3, wherein
   the pipe (85) includes a hole (85ph) in the upper portion of the pipe (85), and
   a hydraulic diameter of the hole (85ph) is equal to or greater than an inner diameter of the pipe (85).
5. The rotary compressor (1) according to claim 4, wherein
   the hole (85ph) is positioned higher than an upper bearing oil supply hole (81h4) provided in the shaft (81).
6. The rotary compressor (1) according to claim 2, wherein
   the lower portion of the pipe (85, 185, 285, or 385) is fixed to the shaft (81) at a position shifted from the lower bearing (31) in a vertical direction.
7. The rotary compressor (1) according to claim 2, wherein
   the pipe (85, 185, 285, or 385) includes a flow path (85fh or 385fh) penetrating in a vertical direction at a portion fixed to the shaft (81).
8. The rotary compressor (1) according to claim 7, wherein
   a total cross-sectional area of flow paths, each of the flow paths being the flow path, is equal to or greater than each of a first cross-sectional area inside the pipe (85, 185, 285, or 385) and a second cross-sectional area between inside of the shaft (81) and the pipe (85, 185, 285, or 385).
9. The rotary compressor (1) according to claim 2, wherein
   an upper portion of the pipe (185, 285, or 385) is provided at a distance from the shaft (81).
10. The rotary compressor (1) according to claim 9, wherein
    the upper portion of the pipe (85, 185, or 385) is positioned higher than an upper bearing oil supply hole (81h4) provided in the shaft (81).
11. The rotary compressor (1) according to claim 1, wherein
    a hydraulic diameter in a first flow path between inside of the shaft (81) and the pipe (85, 185, or 385) is smaller than the hydraulic diameter inside the pipe (85, 185, or 385).
12. The rotary compressor (1) according to claim 1, wherein
    a hydraulic diameter in a first flow path between inside of the shaft (81) and the pipe (85, 185, or 385) is greater than the hydraulic diameter inside the pipe (85, 185, or 385).
13. The rotary compressor (1) according to claim 1, wherein
    an upper end of the pipe (285) is provided below an upper bearing oil supply hole (81h4) provided in the shaft (81).
14. The rotary compressor (1) according to claim 1, wherein
    the rear muffler (34 or 134) includes a wall portion (34b or 134b) projecting downward, and the positive displacement pump (50) is fixed to the wall portion (34b or 134b).
15. The rotary compressor (1) according to claim 14, wherein
    the rear muffler (134) includes in the wall portion (134b), an opening (134h) that communicates with a lower space (SP) in the casing (11).
16. The rotary compressor (1) according to any one of claims 1 to 15, wherein
    the positive displacement pump (50) is a trochoid pump.
17. A refrigeration apparatus (100), comprising:
    the rotary compressor (1) according to any one of claims 1 to 16.