Rotary compressor and refrigeration device

Abstract

A rotary compressor includes: a casing (11); a cylinder (41, 42) disposed inside the casing; a piston (61, 62) configured to eccentrically rotate inside the cylinder; a shaft (81) coupled to the piston (61, 62) and having a cavity (81a) therein; piping (85, 185, 285, 385) disposed inside the cavity (81a) and spaced apart from a wall of the cavity (81a); an upper bearing (32) disposed over the cylinder and configured to rotatably support the shaft; a lower bearing (31) disposed under the cylinder and configured to rotatably support the shaft; a rear muffler (34) disposed under the lower bearing; and a positive displacement pump (50) attached to the rear muffler and configured to discharge oil between the piping and the wall.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a rotary compressor and a refrigeration apparatus including the rotary compressor. The rotary compressor is a compressor that compresses gas in a compression chamber formed in a cylinder by eccentrically rotating a roller in the cylinder. The rotary compressor typically includes a vane for partitioning the compression chamber. Examples of the rotary compressor include what is known as a rolling piston type in which a roller eccentrically rotates while a vane formed as a separate member from the roller contacts the roller, what is known as a swing type in which a vane formed integrally with a roller swings in accordance with the eccentric rotation of the roller, what is known as a hinge vane type in which a roller eccentrically rotates while the tip of a vane is rotatably fitted into a recess of the outer peripheral surface of the roller, and the like.BACKGROUND ART

[0002] Patent Document 1 discloses a rotary compressor including a casing, a cylinder disposed in the casing, a piston for forming a suction compression chamber in the cylinder, a shaft coupled to the piston, and an upper bearing disposed over the cylinder and rotatably supporting the shaft. Patent Document 1 discloses that an oil sump space for storing oil is formed in a lower portion of the casing of the rotary compressor, and a main oil supply channel that communicates with the oil sump space and through which the oil stored in the oil sump space flows upward is formed inside the shaft.RELATED-ART DOCUMENTSPATENT DOCUMENTS

[0003] Patent Document 1: Japanese Laid-Open Patent Application No. 2015-197044SUMMARY OF THE INVENTIONPROBLEM TO BE SOLVED BY THE INVENTION

[0004] In a rotary compressor, it is desirable that an oil supply state does not vary depending on the oil level of lubricating oil and the rotational speed of the rotary compressor.

[0005] The present disclosure provides a rotary compressor having an oil supply structure in which a variation in an oil supply state is small even when the oil level of lubricating oil and the rotational speed of the rotary compressor vary.MEANS TO SOLVE THE PROBLEM

[0006] A rotary compressor of a first aspect includes: a casing; a cylinder disposed inside the casing; a piston configured to eccentrically rotate inside the cylinder; a shaft coupled to the piston and having a cavity therein; piping disposed inside the cavity and spaced apart from a wall of the cavity; an upper bearing disposed over the cylinder and configured to rotatably support the shaft; a lower bearing disposed under the cylinder and configured to rotatably support the shaft; a rear muffler disposed under the lower bearing; and a positive displacement pump attached to the rear muffler and configured to discharge oil between the piping and the wall.

[0007] 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 minimized.

[0008] A rotary compressor of a second aspect is the rotary compressor of the first aspect, wherein a lower portion of the piping is fixed to the shaft.

[0009] According to the rotary compressor of the second aspect, the piping can be integrally fixed to the shaft.

[0010] A rotary compressor of a third aspect is the rotary compressor of the first or second aspect, wherein an upper portion of the piping is fixed to the shaft.

[0011] According to the rotary compressor of the third aspect, the piping can be further firmly fixed to the shaft.

[0012] A rotary compressor of a fourth aspect is the rotary compressor of any one of the first to third aspects, wherein the piping has a hole in an upper portion of the piping, and a hydraulic diameter of the hole is greater than or equal to an inner diameter of the piping.

[0013] According to the rotary compressor of the fourth aspect, the lubricating oil can be supplied from the inside of the piping to the outside through the hole without inhibiting the flow of the lubricating oil.

[0014] A rotary compressor of a fifth aspect is the rotary compressor of the fourth aspect, wherein the hole is located at a position higher than an upper-bearing oil supply hole provided in the shaft.

[0015] According to the rotary compressor of the fifth aspect, the lubricating oil can be stably supplied to the upper bearing.

[0016] A rotary compressor of a sixth aspect is the rotary compressor of the second aspect, wherein the lower portion of the piping is fixed to the shaft at a position shifted with respect to the lower bearing in an up-down direction.

[0017] According to the rotary compressor of the sixth aspect, deformation of the lower bearing caused by deformation of the lower portion of the piping can be suppressed.

[0018] A rotary compressor of a seventh aspect is the rotary compressor of the second aspect, wherein the piping has flow channels penetrating, in an up-down direction, a portion of the piping fixed to the shaft.

[0019] According to the rotary compressor of the seventh aspect, the lubricating oil that has returned through the piping can be discharged.

[0020] A rotary compressor of an eighth aspect is the rotary compressor of the seventh aspect, wherein a total cross-sectional area of the flow channels is greater than or equal to each of a first cross-sectional area of an interior of the piping and a second cross-sectional area between an interior of the shaft and the piping.

[0021] According to the rotary compressor of the eighth aspect, the discharge of the lubricating oil can be facilitated.

[0022] A rotary compressor of a ninth aspect is the rotary compressor of the second aspect, wherein an upper portion of the piping is spaced apart from the shaft.

[0023] According to the rotary compressor of the ninth aspect, the structure of the piping can be simplified.

[0024] A rotary compressor of a tenth aspect is the rotary compressor of the ninth aspect, wherein the upper portion of the piping is located at a position higher than an upper-bearing oil supply hole provided in the shaft.

[0025] According to the rotary compressor of the tenth aspect, the lubricating oil can be stably supplied to the upper bearing.

[0026] A rotary compressor of an eleventh aspect is the rotary compressor of the first aspect, wherein a hydraulic diameter of a first flow channel between an interior of the shaft and the piping is smaller than a hydraulic diameter of an interior of the piping.

[0027] According to the rotary compressor of the eleventh aspect, shortage of the lubricating oil can be suppressed by facilitating the flow of the lubricating oil in the first flow channel and preventing excessive supply of the lubricating oil to the bearings, the piston, and the like.

[0028] A rotary compressor of a twelfth aspect is the rotary compressor of the first aspect, wherein a hydraulic diameter of a first flow channel between an interior of the shaft and the piping is greater than a hydraulic diameter of an interior of the piping.

[0029] According to the rotary compressor of the twelfth aspect, the lubricating oil can be efficiently supplied by reducing the flow velocity of the lubricating oil in the first flow channel.

[0030] A rotary compressor of a thirteenth aspect is the rotary compressor of the first aspect, wherein an upper end of the piping is provided at a position lower than an upper-bearing oil supply hole provided in the shaft.

[0031] According to the rotary compressor of the thirteenth aspect, the piping can be shortened.

[0032] A rotary compressor of a fourteenth aspect is the rotary compressor of the first aspect, wherein the rear muffler includes a wall portion projecting downward, and the positive displacement pump is fixed to the wall portion.

[0033] According to the rotary compressor of the fourteenth aspect, the positive displacement pump can be stably fixed to the rear muffler.

[0034] A rotary compressor of a fifteenth aspect is the rotary compressor of the fourteenth aspect, wherein an interior of the rear muffler is sealed by the positive displacement pump.

[0035] According to the rotary compressor of the fifteenth aspect, the lubricating oil can be stably supplied to the piping.

[0036] A rotary compressor of a sixteenth aspect is the rotary compressor of the fourteenth or fifteenth aspect, wherein the rear muffler has, in the wall portion, an opening that communicates with a lower space in the casing.

[0037] According to the rotary compressor of the sixteenth aspect, the lubricating oil can be stably discharged into the lower space.

[0038] A rotary compressor of a seventeenth aspect is the rotary compressor of any one of the first to sixteenth aspects, wherein the positive displacement pump is a trochoid pump.

[0039] According to the rotary compressor of the seventeenth aspect, the lubricating oil can be stably supplied to the piping.

[0040] A refrigeration apparatus of the first aspect includes the rotary compressor of any one of the first to seventeenth aspects.

[0041] 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 minimized in the rotary compressor.BRIEF DESCRIPTION OF THE DRAWINGS

[0042] [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 of the rotary compressor according to the first embodiment; [FIG. 5] FIG. 5 is a bottom view of a body of the positive displacement pump of the rotary compressor according to the first embodiment; [FIG. 6] FIG. 6 is a plan view of the body of the positive displacement pump of the rotary compressor according to the first embodiment; [FIG. 7] FIG. 7 is a perspective view illustrating a method of attaching the positive displacement pump to a rear muffler in the rotary compressor according to the first embodiment; [FIG. 8] FIG. 8 is a plan view illustrating the operation of the positive displacement pump of the rotary compressor according to the first embodiment; [FIG. 9] FIG. 9 is a cross-sectional view illustrating the flow of lubricating oil in the rotary compressor according to the first embodiment; [FIG. 10] FIG. 10 is a perspective view of piping of the rotary compressor according to the first embodiment; [FIG. 11] FIG. 11 is a cross-sectional view of a rotary compressor according to a second embodiment; [FIG. 12] FIG. 12 is a cross-sectional view of a rotary compressor according to a third embodiment; [FIG. 13] FIG. 13 is a cross-sectional view of a rotary compressor according to a fourth embodiment; [FIG. 14] FIG. 14 is a perspective view of piping of the rotary compressor according to the fourth embodiment; and [FIG. 15] FIG. 15 is a schematic view of a refrigeration apparatus including a rotary compressor according to an embodiment. MODE FOR CARRYING OUT THE INVENTION<First Embodiment>

[0043] Specific examples of a rotary compressor according to a first embodiment will be described below with reference to the drawings. Note 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 modifications within the meaning and scope equivalent to the scope of the claims.

[0044] Note that, in the specification and the drawings according to each embodiment, components having substantially the same or corresponding functional configurations are denoted by the same reference numerals, and redundant descriptions thereof may be omitted. Further, in order to facilitate understanding, components illustrated in the drawings may not be to scale.

[0045] In directions such as parallel, perpendicular, orthogonal, horizontal, vertical, up and down, left and right, and front and rear, deviation is allowed to the extent that the effects of embodiments are not impaired. The shape of a corner is not limited to a right angle, and may be rounded. The terms "parallel", "perpendicular", "orthogonal", "horizontal", and "vertical" may include "substantially parallel", "substantially perpendicular", "substantially orthogonal", "substantially horizontal", and "substantially vertical", respectively.

[0046] 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 being parallel to each other within manufacturing tolerances. Similarly to the term "substantially parallel", the terms "substantially perpendicular", "substantially orthogonal", "substantially horizontal", and "substantially vertical" are intended to include cases where a positional relationship between two lines or two surfaces is within manufacturing tolerances.

[0047] 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 coupled to the piston and having a cavity therein. The piston typically includes a circular roller and a vane configured to partition a compression chamber. Further, the rotary compressor according to the first embodiment includes piping disposed inside the cavity and spaced apart from a wall of the cavity, an upper bearing disposed above the cylinder and configured to rotatably support the shaft, and a lower bearing disposed under the cylinder and configured to rotatably support the shaft. Further, the rotary compressor according to the first embodiment includes a rear muffler disposed under the lower bearing, and a positive displacement pump attached to the rear muffler and configured to discharge oil between the piping and the wall.

[0048] FIG. 1 is a perspective view of a rotary compressor 1, which is an example of the rotary compressor according to the first embodiment. FIG. 2 and FIG. 3 are cross-sectional views of the rotary compressor 1, which is the example of the rotary compressor according to the first embodiment. FIG. 3 is an enlarged cross-sectional view of a compression part 70 of the rotary compressor 1.

[0049] For convenience of description, 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 paper surface 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 the front side of the paper surface. When a cross mark is indicated in a circle of the coordinate axis, it indicates that the coordinate axis is directed toward the back side of the paper surface.

[0050] However, the coordinate system is defined for the purpose of description and is not intended to limit the orientation of the rotary compressor or the like according to the present embodiment.

[0051] Note that, in the drawings, a shaft 81 of the rotary compressor 1 extends in a direction 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.

[0052] A view of an object viewed along the Z-axis from the +Z side in the negative Z-axis direction is referred to as a plan view. Viewing an object along the Z-axis from the +Z side in the negative Z-axis direction is referred to as viewing in a plan view. A view of an object viewed along the Z-axis from the -Z side in the positive Z-axis direction is referred to as a bottom view. Viewing an object along the Z-axis from the -Z side in the positive Z-axis direction is referred to as viewing in a bottom view.

[0053] The rotary compressor 1 compresses a refrigerant. The refrigerant used in the rotary compressor 1 is, for example, carbon dioxide. Note that the refrigerant is not limited to carbon dioxide, and 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]

[0054] The compressor body 10 includes a casing 11, a suction pipe 12, a discharge pipe 13, and a power terminal 15. The casing 11 further includes a plate 14 for installing the compressor body 10.

[0055] The compressor body 10 includes the 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 forms a compression mechanism.

[0056] The electric drive part 80 rotates the shaft 81. The shaft 81 is coupled 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 eccentrically rotates in response to the rotation of the shaft 81. The rotation of each of the piston 61 and the piston 62 causes the refrigerant to be 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 having an internal space 81a. The shaft 81 is a shaft having a cavity therein. Piping 85 is inserted into the internal space 81a. The piping 85 is disposed spaced apart from an inner wall defining the internal space 81a of the shaft 81.

[0057] The shaft 81 includes a main shaft portion 82, an eccentric portion 83, an intermediate coupling portion 84, an eccentric portion 86, and a sub-shaft portion 87. In the shaft 81, the main shaft portion 82, the eccentric portion 83, the intermediate coupling portion 84, the eccentric portion 86, and the sub-shaft portion 87 are integrally formed.

[0058] The main shaft portion 82 has a cylindrical shape or a tubular shape. The upper end of the main shaft portion 82 is connected to a rotor of a motor of the electric drive part 80. The lower end of the main shaft portion 82 is rotatably supported by an upper bearing 32. The lower end of the main shaft portion 82 constitutes a journal.

[0059] The eccentric portion 83 is a cylindrical portion having a diameter greater than the main shaft portion 82. The central axis of the eccentric portion 83 is eccentric from the central axis of the main shaft portion 82. The piston 62 is attached to the eccentric portion 83.

[0060] The intermediate coupling portion 84 couples the eccentric portion 83 and the eccentric portion 86.

[0061] The eccentric portion 86 is a cylindrical portion having a diameter greater than the main shaft portion 82. The central axis of the eccentric portion 86 is eccentric from the central axis of the main shaft portion 82. The eccentric portion 86 is eccentric to the side opposite to the eccentric portion 83 with respect to the central axis of the main shaft portion 82. 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.

[0062] The sub-shaft portion 87 has a cylindrical shape or a tubular shape. The sub-shaft portion 87 is rotatably supported by the lower bearing 31. The sub-shaft portion 87 constitutes a journal.

[0063] The compression part 70 includes the lower bearing 31, a cylinder 41, a middle plate 33, a cylinder 42, and the 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 this order from the lower side. The upper bearing 32 is disposed over the cylinder 41 and the cylinder 42. The lower bearing 31 is disposed under 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 has an oil supply hole, through which lubricating oil is supplied, in a portion through which the shaft 81 penetrates. Further, the shaft 81 has 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 has 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 have a communication hole through which the lubricating oil is supplied to the middle plate 33.

[0064] Further, the compression part 70 includes, inside the cylinder 41, the piston 61 configured to eccentrically rotate by the shaft 81. The lower surface of the piston 61 slides on the upper surface of the lower bearing 31. Further, the upper surface of the piston 61 slides on the lower surface of the middle plate 33.

[0065] Further, the compression part 70 includes, inside the cylinder 42, the piston 62 configured to eccentrically rotate by the shaft 81. The lower surface of the piston 62 slides on the upper surface of the middle plate 33. Further, the upper surface of the piston 62 slides on the lower surface of the upper bearing 32.

[0066] Further, the compression part 70 includes a rear muffler 34 disposed under the lower bearing 31. Further, the compression part 70 includes a positive displacement pump 50 attached to the rear muffler 34.(Positive Displacement Pump 50)

[0067] The positive displacement pump 50 will be described in detail. FIG. 4 is an exploded perspective view of the positive displacement pump 50 of the rotary compressor 1, which is the example of the rotary compressor according to the first embodiment.

[0068] The positive displacement pump 50 discharges the lubricating oil into the internal space 81a of the shaft 81. More specifically, the positive displacement pump 50 discharges the lubricating oil between the piping 85 and the wall defining the internal space 81a (the wall defining the cavity) of the shaft 81. The positive displacement pump 50 is a trochoid pump. Note that, 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.

[0069] 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)

[0070] The body 51 will be described in detail. FIG. 5 is a bottom view of the body 51 of the positive displacement pump 50, which is an example of a positive displacement pump included in the rotary compressor according to the second embodiment. FIG. 6 is a plan view of the body 51 of the positive displacement pump 50, which is the example of the positive displacement pump included in the rotary compressor according to the second embodiment.

[0071] The body 51 has a recess 51g in which the outer rotor 52 and the inner rotor 53 are accommodated. Further, the body 51 has a through hole 51s penetrating through the body 51 from a lower surface 51D, which is the lowermost surface of the body 51, to a bottom surface 51S of the recess 51g. The positive displacement pump 50 suctions the lubricating oil accumulated in an oil sump SP through the through hole 51s.

[0072] A through hole 51t penetrating to the lower surface 51D is formed in the center of the bottom surface 51S of the recess 51g of the body 51.

[0073] The body 51 includes a flange portion 51f at an upper portion thereof. The flange portion extends in a direction parallel to the XY plane. The flange portion 51f has a plurality of through holes 51h through which bolts 55 penetrate. An outer surface 51T, which is a part of a cylindrical surface, is formed in a portion where the flange portion 51f is formed.(Outer Rotor 52)

[0074] The outer rotor 52 is fixed in the recess 51g of the body 51. The outer rotor 52 has, in the center thereof, a through hole 52h into which the inner rotor 53 is inserted. An inner surface 52S of the through hole 52h has a trochoidal cross-sectional shape.(Inner Rotor 53)

[0075] The inner rotor 53 is inserted into the through hole 52h of the outer rotor 52. The inner rotor 53 is rotatable within the through hole 52h of the outer rotor 52. An outer surface 53S of the inner rotor 53 has a trochoidal cross-sectional shape. Note that 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 has a through hole 53h in the center thereof.(Thrust Plate 54)

[0076] The thrust plate 54 is a plate for holding down the inner rotor 53. The thrust plate 54 has a through hole 54h in the center thereof. Further, the thrust plate 54 has a discharge hole 54t through which the lubricating oil is discharged.

[0077] A method of attaching the positive displacement pump 50 to the rear muffler 34 will be described. FIG. 7 is a perspective view illustrating the method of attaching the positive displacement pump 50 to the rear muffler 34 in the rotary compressor 1, which is the example of the rotary compressor according to the first embodiment.

[0078] The rear muffler 34 includes a flat plate portion 34a extending in the X-axis direction and the Y-axis direction, and a wall portion 34b extending from the flat plate portion 34a in the negative Z-axis direction along the Y-axis direction (up-down direction). The wall portion 34b has an inner surface 34S. The wall portion 34b projects downward from the flat plate portion 34a.

[0079] The positive displacement pump 50 is attached by being 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 attached to the rear muffler 34 by press fitting.

[0080] The wall portion 34b has screw holes 34s into which the bolts 55 are inserted. The bolts 55 pass through the through holes 51h of the flange portion 51f and are screwed into the screw holes 34s of the wall portion 34b. By screwing the bolts 55 into the screw holes 34s, the flange portion 51f is fixed to the wall portion 34b by the bolts 55. By fixing the flange portion 51f to the wall portion 34b by the bolts 55, the positive displacement pump 50 is fixed to the rear muffler 34.

[0081] By attaching the positive displacement pump 50 to the rear muffler 34, the interior of the rear muffler 34 is sealed. The lubricating oil discharged into the internal space 81a of the shaft 81 is discharged into the oil sump SP (lower space) through the through hole 51t.

[0082] Next, the operation of the positive displacement pump 50 will be described. FIG. 8 is a plan view illustrating the operation of the positive displacement pump 50 of the rotary compressor 1, which is the example of the rotary compressor according to the first embodiment. More specifically, FIG. 8 is a plan view, that is, a top view of the outer rotor 52 and the inner rotor 53 of the positive displacement pump 50. Upon the inner rotor 53 being rotated in a direction indicated by an arrowed line R with respect to the outer rotor 52, the lubricating oil accumulated in the oil sump SP is suctioned in a range DS. Note that the through hole 51s communicates with the range DS. Then, the lubricating oil is discharged in a range DE. Note that the lubricating oil is discharged through the discharge hole 54t of the thrust plate 54.

[0083] As described above, upon the inner rotor 53 being rotated with respect to the outer rotor 52, the lubricating oil is suctioned from the through hole 51s of the body 51. Then, the suctioned 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 discharge hole 54t of the thrust plate 54.

[0084] The flow of the lubricating oil will be described in detail. FIG. 9 is a cross-sectional view illustrating the flow of the lubricating oil in the rotary compressor according to the first embodiment. The lubricating oil accumulated in the oil sump SP is suctioned from the through hole 51s as indicated by an arrowed dotted line SC. The suctioned lubricating oil is transferred by the rotation of the inner rotor 53 with respect to the outer rotor 52. Then, as indicated by an arrowed dotted line DC, the transferred lubricating oil is discharged into the internal space 81a of the shaft 81.

[0085] The lubricating oil discharged between the internal space 81a of the shaft 81 and the piping 85 is supplied between the internal space 81a and the piping 85 as indicated by arrowed dotted lines in FIG. 3. The lubricating oil supplied between the internal space 81a and the piping 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. Of the lubricating oil supplied between the internal space 81a and the piping 85, lubricating oil remaining without being supplied to the lower bearing 31, the cylinder 41, the cylinder 42 and the upper bearing 32 is discharged into the piping 85. The lubricating oil discharged into the piping 85 is discharged from the internal space 81a of the shaft 81.

[0086] The lubricating oil discharged from the internal space 81a of the shaft 81 is discharged into the oil sump SP through the through hole 51t along an arrowed dotted line DR illustrated in FIG. 9.

[0087] Further, as illustrated in FIG. 9, a lower end 81e of the shaft 81 may be disposed spaced apart from the thrust plate 54. The lower end 81e of the shaft 81 and the thrust plate 54 are separated by a distance h.

[0088] In order to rotate the inner rotor 53, a lower portion of the piping 85 may be fixed to the inner rotor 53. Further, in order to rotate the inner rotor 53, a lower portion of the shaft 81 may be fixed to the inner rotor 53.

[0089] The piping 85 will be described. FIG. 10 is a perspective view of the piping 85 of the rotary compressor 1, which is the example of the rotary compressor according to the first embodiment. The piping 85 includes a pipe 85p and a flange portion 85f.

[0090] The pipe 85p is disposed in the internal space 81a and is spaced apart from the wall defining the internal space 81a (the wall defining the cavity) of the shaft 81. An upper portion of the pipe 85p is inserted into a hole provided in the shaft 81 and fixed. The flange portion 85f is provided at a lower portion of the piping 85. A lower portion of the pipe 85p is fixed to the inner wall of the flange portion 85f by press fitting. There may be a gap between the lower end of the pipe 85p and a step on the inner wall, or the lower end of the pipe 85p may be in contact with the step on the inner wall. The flange portion 85f is fixed to the shaft 81. In other words, the piping 85 has a double-support structure with respect to the shaft 81. Accordingly, the piping 85 is firmly fixed, and thus the influence of vibration can be minimized. Note that the flange portion 85f is fixed to the shaft 81 at a position shifted with respect to the lower bearing 31 in the up-down direction. 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.

[0091] The pipe 85p has a hole 85ph. The hole 85ph is located at a position higher than the oil supply hole (the upper-bearing oil supply hole 81h4) provided for the upper bearing 32. Because the hole 85ph is at a position higher than the oil supply hole (the upper-bearing oil supply hole 81h4) provided for the upper bearing 32, the oil can be supplied to the upper bearing 32. The hydraulic diameter of the hole 85ph may be greater than the inner diameter of the pipe 85p. By setting the hydraulic diameter of the hole 85ph to be greater than or equal to the inner diameter of the pipe 85p, obstruction of the lubricating oil flowing through the pipe 85p by the hole 85ph can be suppressed.

[0092] The number of holes 85ph is not limited to one and may be more than one. 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.

[0093] Further, the hydraulic diameter of a flow channel (a first flow channel) between the internal space 81a of the shaft 81 and the pipe 85p may be smaller than the hydraulic diameter of the interior of the pipe 85p. By setting the hydraulic diameter of the first flow channel to be smaller than the hydraulic diameter of the interior of the pipe 85p, pressure loss caused by surplus oil is reduced, thereby preventing excessive oil supply to each oil supply hole and contributing to reducing oil carry-over.

[0094] The hydraulic diameter of the flow channel (the first flow channel) between the internal space 81a of the shaft 81 and the pipe 85p may be greater than the hydraulic diameter of the interior of the pipe 85p. By setting the hydraulic diameter of the first flow channel to be greater than the hydraulic diameter of the interior of the pipe 85p, the flow velocity in the first flow channel is reduced, thereby allowing for efficient oil supply to each oil supply hole.

[0095] The pipe 85p has the hole 85ph. The hydraulic diameter of the hole 85ph may be greater than or equal to the inner diameter of the pipe 85p. By setting the hydraulic diameter of the hole 85ph to be greater than or equal to the inner diameter of the pipe 85p, obstruction of the lubricating oil flowing through the pipe 85p by the hole 85ph can be suppressed.

[0096] The flange portion 85f is provided with cutout portions 85fh serving as flow channels that penetrate the flange portion 85f in the up-down direction and through which the lubricating oil flows when the piping 85 is fixed to the lower portion of the shaft 81. The lubricating oil is supplied into the internal space 81a through the cutout portions 85fh. The total cross-sectional area of the flow channels defined by the cutout portions 85fh is greater than or equal to each of the cross-sectional area of the interior of the pipe 85p (a first cross-sectional area) and the cross-sectional area between the interior of the shaft 81 and the pipe 85p (a second cross-sectional area). The flow of the lubricating oil can be facilitated by setting the total cross-sectional area of the flow channels defined by the cutout portions 85fh to be greater than or equal to each of the first cross-sectional area and the second cross-sectional area.

[0097] The rotary compressor according to the first embodiment includes the positive displacement pump. Thus, the 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>

[0098] A rotary compressor according to a second embodiment will be described. The rotary compressor according to the second embodiment includes different piping from that of the rotary compressor according to the first embodiment. In the rotary compressor according to the second embodiment, the piping has a cantilever structure.

[0099] FIG. 11 is a cross-sectional view of the rotary compressor according to the second embodiment. The rotary compressor according to the second embodiment includes piping 185, instead of the piping 85 of the rotary compressor 1. The piping 185 includes a pipe 185p and a flange portion 185f. The pipe 185p is disposed in the internal space 81a and spaced apart from the wall defining the internal space 81a (the wall defining the cavity) of the shaft 81. An upper portion of the pipe 185p is disposed spaced apart from the shaft 81. The flange portion 185f is provided at a lower portion of the piping 185. The flange portion 185f is fixed to the shaft 81. That is, the piping 185 has a cantilever structure with respect to the shaft 81. As illustrated in FIG. 11, the upper portion of the piping 185 is not necessarily fixed to the shaft 81. In other words, the upper portion of the piping 185 may be spaced apart from the shaft 81. Note that the upper end of the piping 185 is located at a position higher than the oil supply hole (the upper-bearing oil supply hole 81h4) provided for the upper bearing 32.

[0100] The rotary compressor according to the second embodiment has the same effects as the rotary compressor according to the first embodiment. Further, in the rotary compressor according to the second embodiment, the upper portion of the piping is not fixed, and thus the manufacturing cost can be reduced.<Third Embodiment>

[0101] A rotary compressor according to a third embodiment will be described. The rotary compressor according to the third embodiment includes different piping from that of the rotary compressor according to the first embodiment. In the rotary compressor according to the third embodiment, the piping has a cantilever structure.

[0102] FIG. 12 is a cross-sectional view of the rotary compressor according to the third embodiment. The rotary compressor according to the third embodiment includes piping 285, instead of the piping 85 of the rotary compressor 1. The piping 285 includes a pipe 285p and a flange portion 285f. The pipe 285p is disposed in the internal space 81a and spaced apart from the wall defining the internal space 81a (the wall defining the cavity) of the shaft 81. An upper portion of the pipe 285p is disposed spaced apart from the shaft 81. The flange portion 285f is provided at a lower portion of the piping 285. The flange portion 285f is fixed to the shaft 81. That is, the piping 285 has a cantilever structure with respect to the shaft 81. The piping 285 is even shorter than the piping 185. The lubricating oil can be supplied by spouting the lubricating oil from the piping 285.

[0103] The rotary compressor according to the third embodiment has the same effects as the rotary compressor according to the second embodiment. Further, in the rotary compressor according to the third embodiment, the piping is short, and thus the influence of vibration can be minimized.<Fourth Embodiment>

[0104] A rotary compressor according to a fourth embodiment will be described. The rotary compressor according to the fourth embodiment includes different piping from that of the rotary compressor according to the first embodiment. In the rotary compressor according to the fourth embodiment, the upper portion of the piping of the rotary compressor according to the second embodiment is fixed by an elastic member.

[0105] FIG. 13 is a cross-sectional view of the rotary compressor according to the fourth embodiment. FIG. 14 is a perspective view of piping 385, which is an example of the piping of the rotary compressor according to the fourth embodiment. The piping 385 includes a pipe 385p, a flange portion 385f, and an elastic member 386. The pipe 385p has a hole 385ph. The flange portion 385f is provided with cutout portions 385fh serving as flow channels that penetrate the flange portion 385f in the up-down direction and through which the lubricating oil flows when the piping 385 is fixed to the lower portion of the shaft 81. The rotary compressor according to the fourth embodiment includes the piping 385, instead of the piping 85 of the rotary compressor 1. As illustrated in FIG. 13, an upper portion of the piping 385 is fixed to the shaft 81 by the elastic member 386. The hole 385ph of the piping 385 is located at a position higher than the oil supply hole (upper-bearing oil supply hole 81h4) provided for the upper bearing 32.

[0106] The rotary compressor according to the fourth embodiment has the same effects as the rotary compressor according to the second embodiment. In the rotary compressor according to the fourth embodiment, the piping has a double-support structure, and thus the influence of vibration can be minimized.<Refrigeration Apparatus>

[0107] A refrigeration apparatus including a rotary compressor according to an embodiment will be described. FIG. 15 is a schematic view of a refrigeration apparatus 100, which is an example of the refrigeration apparatus including the rotary compressor according to the embodiment.

[0108] 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 embodiment.

[0109] First, an example in which cooling is performed by the heat exchanger 105 in the refrigeration apparatus 100 will be described. FIG. 15 illustrates connections in the refrigeration apparatus 100 when cooling is performed by the heat exchanger 105.

[0110] A 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 air or the like in the heat exchanger 103. The refrigerant cooled by the heat exchanger 103 is condensed and liquefied, and is 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. The refrigerant evaporates and vaporizes in the heat exchanger 105. Then, the refrigerant discharged from the heat exchanger 105 returns to the compressor 101 and is compressed again. The refrigeration apparatus 100 cools an object by heat of vaporization caused by the evaporation of the refrigerant in the heat exchanger 105.

[0111] Next, an example in which heating is performed by the heat exchanger 105 in the refrigeration apparatus 100 will be described. A refrigerant compressed by the compressor 101 is supplied to the heat exchanger 105 through the four-way valve 102. The refrigeration apparatus 100 heats an object by supplying the compressed high-temperature refrigerant to the heat exchanger 105. The refrigerant subjected to heat exchange in the heat exchanger 105 is condensed and liquefied, and is 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 evaporates and vaporizes by heat exchange with 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, returns to the compressor 101, and is compressed again.

[0112] Although embodiments have been described above, it will be understood that various changes can be made to the configurations and details without departing from the spirit and scope of the claims. Various modifications and improvements such as combinations or substitutions with some or all of other embodiments are possible.

[0113] This application is based on and claims priority to Japanese Patent Application No. 2024-162421, filed on September 19, 2024, the entire contents of which are incorporated herein by reference.DESCRIPTION OF THE REFERENCE NUMERALS

[0114] 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 piping 100 refrigeration apparatus 101 compressor 103, 105 heat exchanger 104 expansion valve

Claims

1. A rotary compressor (1) comprising: a casing (11); a cylinder (41, 42) disposed inside the casing (11); a piston (61, 62) configured to eccentrically rotate inside the cylinder (41, 42); a shaft (81) coupled to the piston (61, 62) and having a cavity (81a) therein; piping (85, 185, 285, 385) disposed inside the cavity (81a) and spaced apart from a wall of the cavity (81a); an upper bearing (32) disposed over the cylinder (41, 42) and configured to rotatably support the shaft (81); a lower bearing (31) disposed under the cylinder (41, 42) and configured to rotatably support the shaft (81); a rear muffler (34) disposed under the lower bearing (31); and a positive displacement pump (50) attached to the rear muffler (34) and configured to discharge oil between the piping (85, 185, 285, 385) and the wall.

2. The rotary compressor (1) according to claim 1, wherein a lower portion of the piping (85, 185, 285, 385) is fixed to the shaft (81).

3. The rotary compressor (1) according to claim 1 or 2, wherein an upper portion of the piping (85, 385) is fixed to the shaft (81).

4. The rotary compressor (1) according to any one of claims 1 to 3, wherein the piping (85) has a hole (85ph) in an upper portion of the piping (85), and a hydraulic diameter of the hole (85ph) is greater than or equal to an inner diameter of the piping (85).

5. The rotary compressor (1) according to claim 4, wherein the hole (85ph) is located at a position 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 piping (85, 185, 285, 385) is fixed to the shaft (81) at a position shifted with respect to the lower bearing (31) in an up-down direction.

7. The rotary compressor (1) according to claim 2, wherein the piping (85, 185, 285, 385) has flow channels (85fh, 385fh) penetrating, in an up-down direction, a portion of the piping (85, 185, 285, 385) fixed to the shaft (81).

8. The rotary compressor (1) according to claim 7, wherein a total cross-sectional area of the flow channels is greater than or equal to each of a first cross-sectional area of an interior of the piping (85, 185, 285, 385) and a second cross-sectional area between an interior of the shaft (81) and the piping (85, 185, 285, 385).

9. The rotary compressor (1) according to claim 2, wherein an upper portion of the piping (185, 285, 385) is spaced apart from the shaft (81).

10. The rotary compressor (1) according to claim 9, wherein the upper portion of the piping (85, 185, 385) is located at a position 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 of a first flow channel between an interior of the shaft (81) and the piping (85, 185, 385) is smaller than a hydraulic diameter of an interior of the piping (85, 185, 385).

12. The rotary compressor (1) according to claim 1, wherein a hydraulic diameter of a first flow channel between an interior of the shaft (81) and the piping (85, 185, 385) is greater than a hydraulic diameter of an interior of the piping (85, 185, 385).

13. The rotary compressor (1) according to claim 1, wherein an upper end of the piping (285) is provided at a position lower than 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) includes a wall portion (34b) projecting downward, and the positive displacement pump (50) is fixed to the wall portion (34b).

15. The rotary compressor (1) according to claim 14, wherein an interior of the rear muffler (34) is sealed by the positive displacement pump (50).

16. The rotary compressor (1) according to claim 14 or 15, wherein the piping (85, 185, 285, 385) communicates with a lower space (SP) in the casing (11).

17. The rotary compressor (1) according to any one of claims 1 to 16, wherein the positive displacement pump (50) is a trochoid pump.

18. A refrigeration apparatus (100) comprising: the rotary compressor (1) according to any one of claims 1 to 17.

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