Rotary compressor and refrigeration apparatus

Abstract

A rotary compressor including: a casing; a cylinder disposed inside the casing; a piston configured to eccentrically rotate inside the cylinder; a hollow shaft coupled to the piston and having an internal space; 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 into the internal space.

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 hollow shaft coupled to the piston and having an internal space; 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 into the internal space.

[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, including a positioning mechanism configured to position the rear muffler with respect to the lower bearing.

[0009] According to the rotary compressor of the second aspect, coaxiality between the lower bearing and the positive displacement pump attached to the rear muffler can be secured by positioning the rear muffler with respect to the lower bearing.

[0010] A rotary compressor of a third aspect is the rotary compressor of the second aspect, wherein the lower bearing includes a first connection portion at a lower portion thereof, the rear muffler includes a second connection portion at an upper portion thereof, the positioning mechanism is composed of the first connection portion and the second connection portion, and the first connection portion and the second connection portion are fitted and fixed to each other.

[0011] According to the rotary compressor of the third aspect, the rear muffler can be positioned with respect to the lower bearing with a simple configuration.

[0012] A rotary compressor of a fourth aspect is the rotary compressor of the second aspect, including a plurality of positioning pins, wherein the lower bearing includes a plurality of first insertion portions into which the plurality of positioning pins are inserted, the rear muffler includes a plurality of second insertion portions into which the plurality of positioning pins are inserted, and the positioning mechanism is composed of the plurality of positioning pins, the plurality of first insertion portions, and the plurality of second insertion portions.

[0013] According to the rotary compressor of the fourth aspect, the rear muffler can be positioned with respect to the lower bearing in a circumferential direction of the shaft.

[0014] A rotary compressor of a fifth aspect is the rotary compressor of any one of the first to fourth aspects, wherein the positive displacement pump includes a flange portion at an upper portion thereof, and the flange portion is fixed to the rear muffler by a bolt.

[0015] According to the rotary compressor of the fifth aspect, the positive displacement pump can be firmly fixed to the rear muffler.

[0016] A rotary compressor of a sixth aspect is the rotary compressor of any one of the first to fourth aspects, wherein the rear muffler includes a wall portion extending in an up-down direction, and the positive displacement pump is fixed to the wall portion by a bolt.

[0017] According to the rotary compressor of the sixth aspect, the positive displacement pump can be firmly fixed to the rear muffler.

[0018] A rotary compressor of a seventh aspect is the rotary compressor of the sixth aspect, wherein the positive displacement pump is fitted to the wall portion.

[0019] According to the rotary compressor of the seventh aspect, the positive displacement pump can be easily positioned with respect to the rear muffler.

[0020] A rotary compressor of an eighth aspect is the rotary compressor of the seventh aspect, wherein the rear muffler has, in the wall portion, an opening communicating with outside of the wall portion.

[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 any one of the first to fourth aspects, wherein the positive displacement pump is attached to the rear muffler by press-fitting.

[0023] According to the rotary compressor of the ninth aspect, the positive displacement pump can be firmly fixed to the rear muffler.

[0024] A rotary compressor of a tenth aspect is the rotary compressor of any one of the first to ninth aspects, wherein a lower surface of an eccentric portion of the shaft slides on an upper surface of the lower bearing.

[0025] According to the rotary compressor of the tenth aspect, the shaft can be supported on the upper surface of the lower bearing in the up-down direction.

[0026] A rotary compressor of an eleventh aspect is the rotary compressor of any one of the first to tenth aspects, wherein the positive displacement pump is a trochoid pump.

[0027] According to the rotary compressor of the eleventh aspect, the lubricating oil can be stably supplied.

[0028] A rotary compressor of a twelfth aspect is the rotary compressor of the eleventh aspect, wherein the trochoid pump includes a thrust plate, and a lower end of the shaft is spaced apart from the thrust plate.

[0029] According to the rotary compressor of the twelfth aspect, friction between the trochoid pump and the shaft can be suppressed.

[0030] A rotary compressor of a thirteenth aspect is the rotary compressor of the eleventh or twelfth aspect, wherein a tube is disposed in the internal space and is spaced apart from an inner wall of the shaft, the trochoid pump includes an inner rotor, and a lower portion of the tube is fixed to the inner rotor.

[0031] According to the rotary compressor of the thirteenth aspect, the configuration can be simplified.

[0032] A rotary compressor of a fourteenth aspect is the rotary compressor of the eleventh or twelfth aspect, wherein the trochoid pump includes an inner rotor, and a lower portion of the shaft is fixed to the inner rotor.

[0033] According to the rotary compressor of the fourteenth aspect, the configuration can be simplified.

[0034] A refrigeration apparatus of the first aspect includes the rotary compressor of any one of the first to fourteenth aspects.

[0035] 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

[0036] [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 cross-sectional view illustrating the flow of lubricating oil in a first modification of the rotary compressor according to the first embodiment; [FIG. 11] FIG. 11 is a cross-sectional view illustrating a second modification of the rotary compressor according to the first embodiment; [FIG. 12] FIG. 12 is a cross-sectional view illustrating the flow of lubricating oil in the second modification of the rotary compressor according to the first embodiment; [FIG. 13] FIG. 13 is a cross-sectional view illustrating the flow of lubricating oil in the second modification of the rotary compressor according to the first embodiment; [FIG. 14] FIG. 14 is a cross-sectional view of a rotary compressor according to a second embodiment; [FIG. 15] FIG. 15 is a cross-sectional view of the rotary compressor according to the second embodiment; [FIG. 16] FIG. 16 is an exploded perspective view of a positive displacement pump of the rotary compressor according to the second embodiment; [FIG. 17] FIG. 17 is a bottom view of a body of the positive displacement pump of the rotary compressor according to the second embodiment; [FIG. 18] FIG. 18 is a plan view of the body of the positive displacement pump of the rotary compressor according to the second embodiment; [FIG. 19] FIG. 19 is a cross-sectional view illustrating the flow of lubricating oil in the rotary compressor according to the second embodiment; [FIG. 20] FIG. 20 is a cross-sectional view illustrating the flow of lubricating oil in a modification of the rotary compressor according to the second embodiment; [FIG. 21] FIG. 21 is a cross-sectional view illustrating a modification of a positioning mechanism of each of the rotary compressors according to the embodiments of the present disclosure; [FIG. 22] FIG. 22 is a cross-sectional view illustrating a modification of the positioning mechanism of each of the rotary compressors according to the embodiments of the present disclosure; and [FIG. 23] FIG. 23 is a schematic view of a refrigeration apparatus including a rotary compressor according to any one of the embodiments. MODE FOR CARRYING OUT THE INVENTION<First Embodiment>

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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 hollow shaft coupled to the piston and having an internal space. 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 an upper bearing disposed above 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 into the internal space.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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]

[0048] 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.

[0049] 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.

[0050] 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. A tube 85 is inserted into the internal space 81a. The tube 85 is disposed spaced apart from an inner wall defining the internal space 81a of the shaft 81.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The intermediate coupling portion 84 couples the eccentric portion 83 and the eccentric portion 86.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] The compression part 70 includes a positioning mechanism 71 configured to position the rear muffler 34 with respect to the lower bearing 31. The positioning mechanism 71 is composed of a first connection portion 311i and a second connection portion 34p.

[0062] The first connection portion 31i is provided at a lower portion of the lower bearing 31. In other words, the lower bearing 31 includes the first connection portion 311i at a lower portion thereof. The first connection portion 311i is a recessed portion recessed upward (toward the +Z side) from the lower surface of the lower bearing 31. The first connection portion 311i is formed around the shaft 81.

[0063] The second connection portion 34p is provided at an upper portion of the rear muffler 34. In other words, the rear muffler 34 includes the second connection portion 34p at an upper portion thereof. The second connection portion 34p is a projecting portion protruding upward (toward the +Z side) from the upper surface of the rear muffler 34. The second connection portion 34p is formed around the shaft 81.

[0064] The first connection portion 31i and the second connection portion 34p are fitted to each other. By fitting the first connection portion 31i and the second connection portion 34p to each other, the first connection portion 31i and the second connection portion 34p are fixed to each other.

[0065] Because the compression part 70 includes the positioning mechanism 71, coaxiality between the lower bearing 31 and the positive displacement pump 50 attached to the rear muffler 34 can be secured.(Positive Displacement Pump 50)

[0066] 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.

[0067] The positive displacement pump 50 discharges the lubricating oil into the internal space 81a 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.

[0068] 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)

[0069] The body 51 will be described in detail. FIG. 5 is a bottom view of the body 51 of the positive displacement pump 50 of the rotary compressor 1, which is the 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 of the rotary compressor 1, which is the example of the rotary compressor according to the first embodiment.

[0070] 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.

[0071] A groove 51d is formed in the bottom surface 51S of the recess 51g of the body 51.

[0072] The body 51 includes, at an upper portion thereof, a plurality of flange portions 51f extending in a direction parallel to the XY plane. The plurality of flange portions 51f have respective through holes 51h through which bolts 55 pass. An outer surface 51T, which is a part of a cylindrical surface, is formed at a portion of the body 51 where the flange portions 51f are formed.(Outer Rotor 52)

[0073] 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)

[0074] 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)

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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 attached to the wall portion 34b. The positive displacement pump 50 may be attached to the rear muffler 34 by press-fitting.

[0079] 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 portions 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 portions 51f are fixed to the wall portion 34b by the bolts 55. By fixing the flange portions 51f to the wall portion 34b by the bolts 55, the positive displacement pump 50 is fixed to the rear muffler 34.

[0080] Note that a gap is formed in a portion where the inner surface 34S of the wall portion 34b 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 gap.

[0081] 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 rotation of the inner rotor 53 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, after the lubricating oil is discharged downward once, the lubricating oil passes through the groove 51d and is discharged through the through hole 53h of the inner rotor 53.

[0082] As described above, upon the rotation of the inner rotor 53 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 through hole 53h of the inner rotor 53.

[0083] 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 1, which is the example of 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 tube 85 through the groove 51d and into the internal space 81a of the shaft 81. The tube 85 includes a pipe 85p and a flange portion 85f.

[0084] The lubricating oil discharged into the tube 85 of the shaft 81 passes through the inside of the tube 85 as indicated by an arrowed dotted line in FIG. 3 and is supplied between the internal space 81a and the tube 85. The lubricating oil supplied between the internal space 81a and the tube 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.

[0085] Further, of the lubricating oil supplied between the internal space 81a and the tube 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 from the internal space 81a of the shaft 81. The lubricating oil discharged from the internal space 81a of the shaft 81 is discharged into the oil sump SP through a gap between the rear muffler 34 and the positive displacement pump 50 along an arrowed dotted line DR indicated in FIG. 9.

[0086] 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 the flow of lubricating oil in a first modification of the rotary compressor 1, which is the example of the rotary compressor according to the first embodiment. The first modification includes a rear muffler 134, instead of the rear muffler 34. The rear muffler 134 has, in a wall portion 134b , an opening 134h communicating with the outside of the wall portion 134b such that the lubricating oil is discharged into the oil sump SP. As indicated by an arrowed dotted line DR in FIG. 10, the lubricating oil may be discharged into the oil sump SP through the opening 134h.

[0087] A compression part according to the first modification includes a positioning mechanism 171 configured to position the rear muffler 134 with respect to the lower bearing 31. The positioning mechanism 171 is composed of the first connection portion 311i and a second connection portion 134p.

[0088] The second connection portion 134p is provided at an upper portion of the rear muffler 134. In other words, the rear muffler 134 includes the second connection portion 134p at an upper portion thereof. The second connection portion 134p is a projecting portion protruding upward (toward the +Z side) from the upper surface of the rear muffler 34. The second connection portion 134p is formed around the shaft 81.

[0089] The first connection portion 311i and the second connection portion 134p are fitted to each other. By fitting the first connection portion 31i and the second connection portion 134p to each other, the first connection portion 311i and the second connection portion 134p are fixed to each other.

[0090] Note that in a case where the rear muffler has the opening, a gap is not necessarily provided between the rear muffler and the positive displacement pump as in the rotary compressor 1.

[0091] Further, as illustrated in FIG. 9 and FIG. 10, 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.

[0092] In order to rotate the inner rotor 53, a lower portion of the tube 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.

[0093] Further, in the rotary compressor according to the first embodiment, the tube in the internal space of the shaft is not limited to the tube 85 illustrated in the above example. FIG. 11 is a cross-sectional view of a rotary compressor 2 in a second modification of the rotary compressor 1, which is the example of the rotary compressor according to the first embodiment. FIG. 12 is a cross-sectional view illustrating the flow of lubricating oil in the second modification of the rotary compressor 1, which is the example of the rotary compressor according to the first embodiment. FIG. 13 is a cross-sectional view illustrating the flow of lubricating oil in the second modification of the rotary compressor 1, which is the example of the rotary compressor according to the first embodiment. The second modification includes a tube 185 instead of the tube 85. The tube 185 includes only a flange portion 85f, and the pipe 85p of the tube 85 is omitted. As shown in the second modification, the pipe may be included or omitted in the rotary compressor according to the first embodiment. In the rotary compressor according to the first embodiment, the shape of the pipe is not limited.

[0094] 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 >

[0095] A rotary compressor according to a second embodiment will be described. The rotary compressor according to the second embodiment differs from the rotary compressor according to the first embodiment in details of a positive displacement pump. FIG. 14 and FIG. 15 are cross-sectional views of a rotary compressor 3, which is an example of the rotary compressor according to the second embodiment. FIG. 15 is an enlarged cross-sectional view of a compression part 170 of the rotary compressor 3.(Positive Displacement Pump 150)

[0096] A positive displacement pump 150 will be described in detail. FIG. 16 is an exploded perspective view of the positive displacement pump 150, which is an example of a positive displacement pump included in the rotary compressor according to the second embodiment.

[0097] The positive displacement pump 150 discharges lubricating oil into the internal space 81a of the shaft 81. The positive displacement pump 150 is a trochoid pump.

[0098] The positive displacement pump 150 includes a body 151, an outer rotor 152, an inner rotor 153, and a thrust plate 154.(Body 151)

[0099] The body 151 will be described in detail. FIG. 17 is a bottom view of the body 151 of the positive displacement pump 150, which is the example of the positive displacement pump included in the rotary compressor according to the second embodiment. FIG. 18 is a plan view of the body 151 of the positive displacement pump 150, which is the example of the positive displacement pump included in the rotary compressor according to the second embodiment.

[0100] The body 151 has a recess 151g in which the outer rotor 152 and the inner rotor 153 are accommodated. Further, the body 151 has a through hole 151s penetrating through the body 151 from a lower surface 151D, which is the lowermost surface of the body 151, to a bottom surface 1518S of the recess 151g. The positive displacement pump 150 suctions the lubricating oil accumulated in the oil sump SP through the through hole 151s.

[0101] A through hole 151t penetrating to the lower surface 151D is formed in the center of the bottom surface 151S of the recess 151g of the body 151.

[0102] The body 151 includes a flange portion 151f at an upper portion thereof. The flange portion 151f extends in a direction parallel to the XY plane. The flange portion 151f has through holes 151h through which bolts 155 pass. The bolts 155 pass through the through holes 151h of the flange portion 151f and are screwed into the screw holes 34s of the wall portion 34b. By screwing the bolts 155 into the screw holes 34s, the flange portion 151f is fixed to the wall portion 34b by the bolts 155. By fixing the flange portion 151f to the wall portion 34b by the bolts 155, the positive displacement pump 150 is fixed to the rear muffler 34.(Outer Rotor 152)

[0103] The outer rotor 152 is fixed in the recess 151g of the body 151. The outer rotor 152 has, in the center thereof, a through hole 152h into which the inner rotor 153 is inserted. An inner surface of the through hole 152h has a trochoidal cross-sectional shape.(Inner Rotor 153)

[0104] The inner rotor 153 is inserted into the through hole 152h of the outer rotor 152. The inner rotor 153 is rotatable within the through hole 152h of the outer rotor 152. An outer surface of the inner rotor 153 has a trochoidal cross-sectional shape. Note that the number of teeth of the inner rotor 153 is one less than the number of teeth of the outer rotor 152. The inner rotor 153 has a through hole 153h in the center thereof.(Thrust Plate 154)

[0105] The thrust plate 154 is a plate for holding down the inner rotor 153. The thrust plate 154 has a through hole 154h in the center thereof. Further, the thrust plate 154 has a discharge hole 154t through which the lubricating oil is discharged.

[0106] The flow of the lubricating oil will be described in detail. FIG. 19 is a cross-sectional view illustrating the flow of the lubricating oil in the rotary compressor according to the second embodiment. The lubricating oil accumulated in the oil sump SP is suctioned from the through hole 151s as indicated by an arrowed dotted line SC. The suctioned lubricating oil is transferred by the rotation of the inner rotor 153 with respect to the outer rotor 152. Then, as indicated by an arrowed dotted line DC, the transferred lubricating oil is discharged into the internal space 81a of the shaft 81.

[0107] The lubricating oil discharged between the internal space 81a of the shaft 81 and the tube 85 is supplied between the internal space 81a and the tube 85 as indicated by arrowed dotted lines in FIG. 15. The lubricating oil supplied between the internal space 81a and the tube 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 tube 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 tube 85. The lubricating oil discharged into the tube 85 is discharged from the internal space 81a of the shaft 81.

[0108] The lubricating oil discharged from the internal space 81a of the shaft 81 is discharged into the oil sump SP through the through hole 151t along an arrowed dotted line DR illustrated in FIG. 19.

[0109] Upon rotation of the inner rotor 153 with respect to the outer rotor 152, the lubricating oil is suctioned from the through hole 151s of the body 151. The suctioned lubricating oil is transferred as the outer rotor 152 rotates. Then, the transferred lubricating oil is discharged into the internal space 81a of the shaft 81 through the discharge hole 154t of the inner rotor 153.

[0110] Further, in the rotary compressor according to the second embodiment, the tube in the internal space of the shaft is not limited to the tube 85 illustrated in the above example. FIG. 20 is a cross-sectional view illustrating the flow of lubricating oil in a modification of the rotary compressor according to the second embodiment. This modification includes a tube 185 instead of the tube 85. The tube 185 includes only a flange portion 85f, and the pipe 85p of the tube 85 is omitted. As shown in this modification, the pipe may be included or omitted in the rotary compressor according to the second embodiment. In the rotary compressor according to the second embodiment, the shape of the pipe is not limited.

[0111] Similar to the rotary compressor according to the first embodiment, the rotary compressor according to the second embodiment includes the positive displacement pump, and 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.<Modifications of Positioning Mechanism>

[0112] A modification of the positioning mechanism will be described. FIG. 21 is a cross-sectional view illustrating a positioning mechanism 271, which is the modification of the positioning mechanism of each of the rotary compressors according the embodiments of the present disclosure. FIG. 21 is a cross-sectional view in which the positioning mechanism 71 of FIG. 9 is changed to the positioning mechanism 271.

[0113] The positioning mechanism 271 has a first connection portion 231p that is a projecting portion of a lower bearing 231 and a second connection portion 234i that is a recessed portion of a rear muffler 234. The positioning mechanism 271 has the first connection portion 231p that is the projecting portion, instead of the first connection portion 31i that is the recessed portion. Further, the positioning mechanism 271 has the second connection portion 234i that is the recessed portion, instead of the second connection portion 34p that is the projecting portion.

[0114] The lower bearing 231 has a configuration common to that of the lower bearing 31 except for the first connection portion 231p. Further, the rear muffler 234 has a configuration common to that of the rear muffler 34 except for the second connection portion 234i.

[0115] The positioning mechanism 271 is configured to position the rear muffler 234 with respect to the lower bearing 231. The positioning mechanism 271 is composed of the first connection portion 231p and the second connection portion 234i.

[0116] The first connection portion 231p is provided at a lower portion of the lower bearing 231. In other words, the lower bearing 231 includes the first connection portion 231p at a lower portion thereof. The first connection portion 231p is the projecting portion protruding downward (toward the -Z side) from the lower surface of the lower bearing 231. The first connection portion 231p is formed around the shaft 81.

[0117] The second connection portion 234i is provided at an upper portion of the rear muffler 234. In other words, the rear muffler 234 includes the second connection portion 234i at an upper portion thereof. The second connection portion 234i is the recess portion recessed downward (toward the -Z side) from the upper surface of the rear muffler 234. The second connection portion 234i is formed around the shaft 81.

[0118] The first connection portion 231p and the second connection portion 234i are fitted to each other. By fitting the first connection portion 231p and the second connection portion 234i to each other, the first connection portion 231p and the second connection portion 234i are fixed to each other.

[0119] Another modification of the positioning mechanism will be described. FIG. 22 is a cross-sectional view illustrating a positioning mechanism 371, which is a modification of the positioning mechanism of each of the rotary compressors according to the embodiments of the present disclosure. FIG. 22 is a cross-sectional view in which the positioning mechanism 71 of FIG. 9 is changed to the positioning mechanism 371.

[0120] The positioning mechanism 371 has a positioning pin 372, a first insertion portion 331h that is provided in a lower bearing 331 and into which the positioning pin 372 is inserted, and a second insertion portion 334h that is provided in a rear muffler 234 and into which the positioning pin 372 is inserted.

[0121] The lower bearing 331 has a configuration common to that of the lower bearing 31 except for the first insertion portion 331h. The rear muffler 334 has a configuration common to that of the rear muffler 34 except for the second insertion portion 334h.

[0122] The positioning mechanism 371 is configured to position the rear muffler 334 with respect to the lower bearing 331. The positioning mechanism 371 is composed of a plurality of positioning pins 372, a plurality of first insertion portions 331h, and a plurality of second insertion portions 334h.

[0123] The first insertion portions 331h are provided in lower portions of the lower bearing 331. In other words, the lower bearing 331 includes the first insertion portions 331h in lower portions thereof. The first insertion portions 331h are fitting holes recessed upward (toward the +Z side) from the lower surface of the lower bearing 331. The plurality of first insertion portions 331h are formed around the shaft 81 at equal intervals.

[0124] The second insertion portions 334h are provided in upper portions of the rear muffler 334. In other words, the rear muffler 34 includes the second insertion portions 334h in upper portions thereof. The second insertion portions 334h are fitting holes recessed downward (toward the -Z side) from the upper surface of the rear muffler 334. The plurality of the second insertion portions 334h are formed around the shaft 81 at equal intervals.

[0125] Each of the positioning pins 372 is inserted into a corresponding one of the first insertion portions 331h and a corresponding one of the second insertion portions 334h. By inserting each of the positioning pins 372 into the corresponding one of the first insertion portions 331h and the corresponding one of the second insertion portions 334h, the corresponding one of the first insertion portions 331h and the corresponding one of the second insertion portions 334h are positioned. At least two or more, that is, the plurality of positioning pins 372, the plurality of first insertion portions 331h, and the plurality of second insertion portions 334h are provided.<Refrigeration Apparatus>

[0126] A refrigeration apparatus including a rotary compressor according to any one of the embodiments will be described. FIG. 23 is a schematic view of a refrigeration apparatus 100, which is an example of the refrigeration apparatus including the rotary compressor according to any one of the embodiments.

[0127] 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.

[0128] First, an example in which cooling is performed by the heat exchanger 105 in the refrigeration apparatus 100 will be described. FIG. 23 illustrates connections in the refrigeration apparatus 100 when cooling is performed by the heat exchanger 105.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] This application is based on and claims priority to Japanese Patent Application No. 2024-162422, filed on September 19, 2024, the entire contents of which are incorporated herein by reference.DESCRIPTION OF THE REFERENCE NUMERALS

[0133] 1, 2, 3 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, 185 tube 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 hollow shaft (81) coupled to the piston (61, 62) and having an internal space (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, 150) attached to the rear muffler (34) and configured to discharge oil into the internal space (81a).

2. The rotary compressor (1) according to claim 1, comprising: a positioning mechanism (71, 171, 271, 371) configured to position the rear muffler (34, 234, 334) with respect to the lower bearing (31, 231, 331).

3. The rotary compressor (1) according to claim 2, wherein the lower bearing (31, 231) includes a first connection portion (31i, 231p) at a lower portion thereof, the rear muffler (34, 234) includes a second connection portion (34p, 234i) at an upper portion thereof, the positioning mechanism (71, 171, 271) is composed of the first connection portion (31i, 231p) and the second connection portion (34p, 234i), and the first connection portion (31i, 231p) and the second connection portion (34p, 234i) are fitted and fixed to each other.

4. The rotary compressor (1) according to claim 2, comprising: a plurality of positioning pins (372), wherein the lower bearing (331) includes a plurality of first insertion portions (331h) into which the plurality of positioning pins (372) are inserted, the rear muffler (334) includes a plurality of second insertion portions (334h) into which the plurality of positioning pins (372) are inserted, and the positioning mechanism (371) is composed of the plurality of positioning pins (372), the plurality of first insertion portions (331h), and the plurality of second insertion portions (334h).

5. The rotary compressor (1) according to any one of claims 1 to 4, wherein the positive displacement pump (50, 150) includes a flange portion (51f, 151f) at an upper portion thereof, and the flange portion (51f, 151f) is fixed to the rear muffler (34) by a bolt (55, 155).

6. The rotary compressor (1) according to any one of claims 1 to 4, wherein the rear muffler (34) includes a wall portion (34b) extending in an up-down direction, and the positive displacement pump (50, 150) is fixed to the wall portion (34b) by a bolt (55, 155).

7. The rotary compressor (1) according to claim 6, wherein the positive displacement pump (50, 150) is fitted to the wall portion (34b).

8. The rotary compressor (1) according to claim 7, wherein the rear muffler (34) has, in the wall portion (134b), an opening (134h) communicating with outside of the wall portion (134b).

9. The rotary compressor (1) according to any one of claims 1 to 4, wherein the positive displacement pump (50, 150) is attached to the rear muffler (34) by press-fitting.

10. The rotary compressor (1) according to any one of claims 1 to 9, wherein a lower surface of an eccentric portion of the shaft slides on an upper surface of the lower bearing (31).

11. The rotary compressor (1) according to any one of claims 1 to 10, wherein the positive displacement pump (50, 150) is a trochoid pump (50, 150).

12. The rotary compressor (1) according to claim 11, wherein the trochoid pump (50, 150) includes a thrust plate (54, 154), and a lower end of the shaft (81) is spaced apart from the thrust plate (54, 154).

13. The rotary compressor (1) according to claim 11 or 12, wherein a tube (85, 185) is disposed in the internal space (81a) and is spaced apart from an inner wall of the shaft (81), the trochoid pump (50, 150) includes an inner rotor (53, 153), and a lower portion of the tube (85, 185) is fixed to the inner rotor (53, 153).

14. The rotary compressor (1) according to claim 11 or 12, wherein the trochoid pump (50, 150) includes an inner rotor (53, 153), and a lower portion of the shaft (81) is fixed to the inner rotor (53, 153).

15. A refrigeration apparatus (100) comprising: the rotary compressor (1) according to any one of claims 1 to 14.

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