Rotary compressor and refrigeration apparatus

Abstract

A rotary compressor comprising: a casing; a cylinder disposed inside the casing; a piston eccentrically rotating inside the cylinder; a hollow shaft coupled to the piston and having an internal space; an upper bearing disposed above the cylinder and pivotally supporting the shaft; a lower bearing disposed below the cylinder and pivotally supporting the shaft; a rear muffler disposed below the lower bearing; and a positive displacement pump attached to the rear muffler and discharging oil into the internal space.

Description

Rotary Compressor and Refrigeration Device

[0001] The present disclosure relates to a rotary compressor and a refrigeration device including the same. A rotary compressor is a compressor that compresses gas in a compression chamber formed in a cylinder by eccentrically rotating a roller in the cylinder. A rotary compressor generally has a vane for partitioning the compression chamber. Rotary compressors include a so-called rolling piston type in which a vane separate from the roller contacts the roller while the roller eccentrically rotates, a so-called swing type in which a vane formed integrally with the roller swings as the roller eccentrically rotates, a so-called hinge vane type in which the tip of the vane is rotatably fitted in a recess on the outer peripheral surface of the roller and the roller eccentrically rotates, and the like.

[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 connected to the piston, and an upper bearing disposed above the cylinder and supporting the shaft. Patent Document 1 discloses that an oil reservoir space for storing oil is formed at the lower part of the casing of the rotary compressor, and an oil supply main path communicating with the oil reservoir space and through which the oil stored in the oil reservoir space flows upward is formed inside the shaft.

[0003] Japanese Patent Application Laid-Open No. 2015-197044

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

[0006] The rotary compressor of the first aspect comprises a casing, a cylinder disposed inside the casing, a piston that rotates eccentrically inside the cylinder, a hollow shaft connected to the piston and having an internal space, an upper bearing disposed above the cylinder and supporting the shaft, a lower bearing disposed below the cylinder and supporting the shaft, a rear muffler disposed below the lower bearing, and a positive displacement pump attached to the rear muffler and discharging oil into the internal space.

[0007] According to the rotary compressor from the first perspective, the influence of the oil level in the lubricating oil and the rotational speed in the rotary compressor can be reduced.

[0008] The rotary compressor in the second view is the rotary compressor in the first view, which is provided with a positioning mechanism for positioning the rear muffler relative to the lower bearing.

[0009] According to the second perspective of the rotary compressor, by positioning the rear muffler relative to the lower bearing, coaxiality between the lower bearing and the positive displacement pump attached to the rear muffler can be ensured.

[0010] The rotary compressor in the third view is a rotary compressor in the second view, wherein the lower bearing has a first connecting portion at its lower part, the rear muffler has a second connecting portion at its upper part, the positioning mechanism is composed of the first connecting portion and the second connecting portion, and the first connecting portion and the second connecting portion are fitted together and fixed to each other.

[0011] According to the rotary compressor from the third perspective, the rear muffler can be positioned relative to the lower bearing with a simple configuration.

[0012] The rotary compressor of the fourth perspective is a rotary compressor of the second perspective having a plurality of positioning pins, the lower bearing having a plurality of first insertion parts through which the plurality of positioning pins are inserted, the rear muffler having a plurality of second insertion parts through which the plurality of positioning pins are inserted, and the positioning mechanism is composed of a plurality of positioning pins, a plurality of first insertion parts, and a plurality of second insertion parts.

[0013] According to the rotary compressor from the fourth perspective, the rear muffler can be positioned relative to the lower bearing in the circumferential direction of the shaft.

[0014] The rotary compressor in the fifth view is a rotary compressor in any of the first to fourth views, wherein the positive displacement pump has a flange portion at the top, and the flange portion is fixed to the rear muffler by bolts.

[0015] According to the fifth perspective on rotary compressors, the positive displacement pump can be firmly fixed to the rear muffler.

[0016] The rotary compressor of the sixth viewpoint is a rotary compressor of any of the first to fourth viewpoints, wherein the rear muffler has a wall portion extending in the vertical direction, and the positive displacement pump is fixed to the wall portion by bolts.

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

[0018] The rotary compressor in the seventh aspect is a rotary compressor in the sixth aspect in which the positive displacement pump is fitted and mounted to the wall.

[0019] According to the rotary compressor in the seventh perspective, the positioning of the positive displacement pump relative to the rear muffler can be easily facilitated.

[0020] The rotary compressor of the eighth viewpoint is the rotary compressor of the seventh viewpoint, wherein the rear muffler has an opening in the wall portion that communicates with the outside of the wall portion.

[0021] According to the rotary compressor from the eighth perspective, lubricating oil can be discharged more efficiently.

[0022] The rotary compressor of the ninth perspective is a rotary compressor of any of the first to fourth perspectives, in which the positive displacement pump is attached to the rear muffler by press-fitting.

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

[0024] The rotary compressor of the tenth viewpoint is a rotary compressor of any of the first to ninth viewpoints, wherein the lower surface of the eccentric portion of the shaft slides with the upper surface of the lower bearing.

[0025] According to the rotary compressor of the tenth perspective, the shaft can be supported vertically on the upper surface of the lower bearing.

[0026] The rotary compressor in the eleventh viewpoint is a rotary compressor in any of the first to tenth viewpoints, wherein the positive displacement pump is a trochoid pump.

[0027] According to the rotary compressor described in the eleventh perspective, a stable supply of lubricating oil can be achieved.

[0028] The rotary compressor in the twelfth view is the rotary compressor in the eleventh view in which the trochoid pump is equipped with a thrust plate and the lower end of the shaft is separated from the thrust plate.

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

[0030] The rotary compressor of the 13th aspect is a rotary compressor of either the 11th or 12th aspect in which a pipe is arranged in the internal space away from the inner wall of the shaft, the trochoid pump is equipped with an inner rotor, and the lower part of the pipe is fixed to the inner rotor.

[0031] According to the rotary compressor from the 13th perspective, the configuration can be simplified.

[0032] The rotary compressor of the 14th aspect is a rotary compressor of either the 11th or 12th aspect, wherein the trochoid pump is equipped with an inner rotor, and the lower part of the shaft is fixed to the inner rotor.

[0033] According to the rotary compressor from the 14th perspective, the configuration can be simplified.

[0034] The refrigeration system of the first perspective is a refrigeration system equipped with a rotary compressor of any of the first to fourteenth perspectives.

[0035] According to the refrigeration system of the first perspective, the influence of the oil level in the lubricating oil and the rotational speed in the rotary compressor can be reduced in a rotary compressor.

[0036] Figure 1 is a perspective view of a rotary compressor according to the first embodiment. Figure 2 is a cross-sectional view of a rotary compressor according to the first embodiment. Figure 3 is a cross-sectional view of a rotary compressor according to the first embodiment. Figure 4 is an exploded perspective view of a positive displacement pump in a rotary compressor according to the first embodiment. Figure 5 is a bottom view of the body of the positive displacement pump in a rotary compressor according to the first embodiment. Figure 6 is a plan view of the body of the positive displacement pump in a rotary compressor according to the first embodiment. Figure 7 is a perspective view illustrating the mounting of the positive displacement pump in a rotary compressor according to the first embodiment. Figure 8 is a plan view illustrating the operation of the positive displacement pump in a rotary compressor according to the first embodiment. Figure 9 is a cross-sectional view illustrating the flow of lubricating oil in a rotary compressor according to the first embodiment. Figure 10 is a cross-sectional view illustrating the flow of lubricating oil in a first modified example of the rotary compressor according to the first embodiment. Figure 11 is a cross-sectional view of a second modified example of the rotary compressor according to the first embodiment. Figure 12 is a cross-sectional view illustrating the flow of lubricating oil in a second modified example of the rotary compressor according to the first embodiment. Figure 13 is a cross-sectional view illustrating the flow of lubricating oil in a second modified example of the rotary compressor according to the first embodiment. Figure 14 is a cross-sectional view of a rotary compressor according to the second embodiment. Figure 15 is a cross-sectional view of a rotary compressor according to the second embodiment. Figure 16 is an exploded perspective view of a positive displacement pump in a rotary compressor according to the second embodiment. Figure 17 is a bottom view of the body of the positive displacement pump in a rotary compressor according to the second embodiment. Figure 18 is a plan view of the body of the positive displacement pump in a rotary compressor according to the second embodiment. Figure 19 is a cross-sectional view illustrating the flow of lubricating oil in a rotary compressor according to the second embodiment. Figure 20 is a cross-sectional view illustrating the flow of lubricating oil in a modified example of the rotary compressor according to the second embodiment. Figure 21 is a cross-sectional view illustrating a modified example of the positioning mechanism in a rotary compressor according to the embodiment of this disclosure. Figure 22 is a cross-sectional view illustrating a modified example of the positioning mechanism in a rotary compressor according to the embodiment of this disclosure. Figure 23 is a schematic diagram of a refrigeration system equipped with a rotary compressor according to this embodiment.

[0037] <First Embodiment> A specific example of the rotary compressor of the first embodiment will be described below with reference to the drawings. However, this disclosure is not limited to these examples and is intended to include all modifications within the meaning and scope of the equivalents of the claims, as indicated by the claims.

[0038] In addition, regarding the descriptions and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be denoted by the same reference numerals, thereby omitting redundant explanations. Furthermore, for ease of understanding, the scale of each part in the drawings may differ from the actual scale.

[0039] A degree of deviation is permissible in directions such as parallel, right angles, orthogonal, horizontal, vertical, up and down, left and right, and front and back, as long as it does not impair the effects of the embodiment. The shape of the corners is not limited to right angles and may be rounded. Parallel, right angles, orthogonal, horizontal, and vertical may include approximately parallel, approximately right angles, approximately orthogonal, approximately horizontal, and approximately vertical, respectively.

[0040] For example, "approximately parallel" means that two lines or two planes can be treated as parallel to each other within a manufacturingly acceptable range, even if they are not perfectly parallel. Similarly, "approximately right angle," "approximately perpendicular," "approximately horizontal," and "approximately vertical" are intended to apply as long as the relative positions of the two lines or two planes are within a manufacturingly acceptable range.

[0041] A rotary compressor according to the first embodiment will now be described. The rotary compressor according to the first embodiment comprises a casing, a cylinder disposed inside the casing, a piston that rotates eccentrically inside the cylinder, and a hollow shaft connected to the piston and having an internal space. The piston is generally composed of a circular roller and vanes that partition the compression chamber. The rotary compressor according to the first embodiment also comprises an upper bearing disposed above the cylinder and supporting the shaft, a lower bearing disposed below the cylinder and supporting the shaft, a rear muffler disposed below the lower bearing, and a positive displacement pump attached to the rear muffler that discharges oil into the internal space.

[0042] FIG. 1 is a perspective view of a rotary compressor 1 which is an example of a rotary compressor according to the first embodiment. FIGS. 2 and 3 are cross-sectional views of a rotary compressor 1 which is an example of a rotary compressor according to the first embodiment. FIG. 3 is an enlarged cross-sectional view of a compression part 70 in the rotary compressor 1.

[0043] In the drawings, for convenience of explanation, a virtual three-dimensional coordinate system (XYZ orthogonal coordinate system) composed of an X-axis, a Y-axis, and a Z-axis (XYZ axes) orthogonal to each other may be set. For example, for a coordinate axis perpendicular to the paper surface of the drawing, when a black dot is shown in the circle of the coordinate axis, it represents that the coordinate axis is facing the front side with respect to the paper surface. Further, when a cross mark is shown in the circle of the coordinate axis, it represents that the coordinate axis is facing the back side with respect to the paper surface.

[0044] However, the coordinate system is defined for the purpose of explanation and does not limit the posture of the rotary compressor and the like according to the present embodiment.

[0045] In the following drawings, the shaft 81 of the rotary compressor 1 extends in the direction along the Z-axis, and in a plane parallel to the XY plane including the X-axis and the Y-axis, the pistons 61 and 62 of the rotary compressor 1 rotate respectively.

[0046] A view of an object looking from the +Z side in the opposite direction of the Z-axis along the Z-axis direction is called a plan view. Looking at an object from the +Z side in the opposite direction of the Z-axis along the Z-axis direction is called a plan view. A view of an object looking from the -Z side in the direction of the Z-axis along the Z-axis direction is called a bottom view. Looking at an object from the -Z side in the direction of the Z-axis along the Z-axis direction is called 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-based, hydrofluoroolefin-based, or hydrocarbon-based refrigerant. The rotary compressor 1 includes a compressor main body 10 and an accumulator 20.

[0048] [Compressor Main Body 10] The compressor main body 10 includes a casing 11, an intake pipe 12, an exhaust pipe 13, and power terminals 15. Further, the casing 11 includes a plate 14 for installing the compressor main body 10.

[0049] The compressor main body 10 includes a compression section 70 and an electric section 80 inside the casing 11. The electric section 80 rotates a shaft 81. The compression section 70 compresses the refrigerant supplied from the intake pipe 12. The refrigerant compressed in the compression section 70 is discharged from the exhaust pipe 13 to the outside of the rotary compressor 1. The compression section 70 constitutes a compression mechanism.

[0050] The electric section 80 rotates the shaft 81. The shaft 81 is connected to each of the pistons 61 and 62. In the compression section 70, the shaft 81 rotated by the electric section 80 rotates each of the pistons 61 and 62. Each of the pistons 61 and 62 rotates eccentrically when the shaft 81 rotates. When each of the pistons 61 and 62 rotates, the refrigerant is compressed in the compression section 70. Each of the pistons 61 and 62 is constituted by a circular roller and a vane partitioning a compression chamber. The shaft 81 is a hollow shaft having an internal space 81a. The shaft 81 is a shaft with a hollow interior. A pipe 85 is inserted into the internal space 81a. The pipe 85 is arranged separated from the inner wall forming the internal space 81a of the shaft 81.

[0051] The shaft 81 has a main shaft portion 82, an eccentric portion 83, an intermediate connecting 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 connecting portion 84, the eccentric portion 86, and the sub-shaft portion 87 are integrally formed.

[0052] The main shaft portion 82 has a columnar or cylindrical shape. The upper end of the main shaft portion 82 is connected to the rotor of the motor in the electric section 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 part with a larger diameter than the main shaft portion 82. The central axis of the eccentric portion 83 is eccentric to the central axis of the main shaft portion 82. The piston 62 is attached to the eccentric portion 83.

[0054] The intermediate connecting section 84 connects the eccentric section 83 and the eccentric section 86.

[0055] The eccentric portion 86 is a cylindrical part with a larger diameter 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 with respect to the central axis of the main shaft portion 82 on the opposite side from the eccentric portion 83. The piston 61 is attached to the eccentric portion 86. The lower surface of the eccentric portion 86 slides against the upper surface of the lower bearing 31.

[0056] The sub-shaft portion 87 has a cylindrical or cylindrical 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 section 70 comprises a lower bearing 31, a cylinder 41, a middle plate 33, a cylinder 42, and an upper bearing 32. The lower bearing 31, cylinder 41, middle plate 33, cylinder 42, and upper bearing 32 are stacked in order from bottom to top. The upper bearing 32 is positioned above each of the cylinders 41 and 42. The lower bearing 31 is positioned below each of the cylinders 41 and 42. A shaft 81 passes through each of the lower bearing 31, cylinder 41, middle plate 33, cylinder 42, and upper bearing 32. Each of the lower bearing 31, cylinder 41, middle plate 33, cylinder 42, and upper bearing 32 is provided with an oil supply hole through which the shaft 81 passes, for supplying lubricating oil. The shaft 81 also has a communication hole that penetrates from the internal space 81a to the outside of the shaft 81 in order to supply lubricating oil to each of the lower bearing 31, cylinder 41, cylinder 42, and 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, respectively, for supplying lubricating oil to the lower bearing 31, cylinder 41, cylinder 42, and upper bearing 32. The shaft 81 may also have a communication hole for supplying lubricating oil to the middle plate 33.

[0058] The compression section 70 includes a piston 61 inside the cylinder 41 that rotates eccentrically by a shaft 81. The lower surface of the piston 61 slides against the upper surface of the lower bearing 31. The upper surface of the piston 61 also slides against the lower surface of the middle plate 33.

[0059] Furthermore, the compression section 70 includes a piston 62 inside the cylinder 42 that rotates eccentrically by a shaft 81. The lower surface of the piston 62 slides against the upper surface of the middle plate 33. The upper surface of the piston 62 also slides against the lower surface of the upper bearing 32.

[0060] Furthermore, the compression unit 70 includes a rear muffler 34 positioned below the lower bearing 31. In addition, the compression unit 70 includes a positive displacement pump 50 attached to the rear muffler 34.

[0061] The compression section 70 includes a positioning mechanism 71 for positioning the rear muffler 34 relative to the lower bearing 31. The positioning mechanism 71 is composed of a first connecting portion 31i and a second connecting portion 34p.

[0062] The first connecting portion 31i is provided at the lower part of the lower bearing 31. In other words, the lower bearing 31 has the first connecting portion 31i at its lower part. The first connecting portion 31i is a recess that is recessed upward (towards the +Z side) from the lower surface of the lower bearing 31. The first connecting portion 31i is formed around the shaft 81.

[0063] The second connecting portion 34p is provided on the upper part of the rear muffler 34. In other words, the rear muffler 34 has the second connecting portion 34p on its upper part. The second connecting portion 34p is a protrusion that extends upward (towards the +Z side) from the upper surface of the rear muffler 34. The second connecting portion 34p is formed around the shaft 81.

[0064] The first connecting portion 31i and the second connecting portion 34p fit together. By fitting together the first connecting portion 31i and the second connecting portion 34p, they are fixed to each other.

[0065] The compression section 70 is equipped with a positioning mechanism 71, which ensures coaxiality between the lower bearing 31 and the positive displacement pump 50 attached to the rear muffler 34.

[0066] (Positive displacement pump 50) The positive displacement pump 50 will be described in detail. Figure 4 is an exploded perspective view of the positive displacement pump 50 in a rotary compressor 1, which is an example of a rotary compressor according to the first embodiment.

[0067] The positive displacement pump 50 discharges lubricating oil into the internal space 81a of the shaft 81. The positive displacement pump 50 is a trochoid pump. In the rotary compressor according to the first embodiment, the positive displacement pump is not limited to a trochoid pump, but 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 comprises a main body 51, an outer rotor 52, an inner rotor 53, and a thrust plate 54.

[0069] (Main body 51) The main body 51 will be described in detail. Figure 5 is a bottom view of the main body 51 of the positive displacement pump 50 in a rotary compressor 1, which is an example of a rotary compressor according to the first embodiment. Figure 6 is a top view of the main body 51 of the positive displacement pump 50 in a rotary compressor 1, which is an example of a rotary compressor according to the first embodiment.

[0070] The main body 51 has a recess 51g at its top in which the outer rotor 52 and inner rotor 53 are housed. The main body 51 also has a through hole 51s that penetrates from the bottom surface 51D, which is the lowest surface, to the bottom surface 51S of the recess 51g. The positive displacement pump 50 sucks the lubricating oil accumulated in the oil reservoir SP through the through hole 51s.

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

[0072] The main body 51 has a plurality of flange portions 51f extending in a direction parallel to the XY plane at its upper end. Each of the plurality of flange portions 51f has a through hole 51h through which a bolt 55 passes. An outer surface 51T, which is part of a cylindrical surface, is formed in the portion where the flange portion 51f is formed.

[0073] (Outer rotor 52) The outer rotor 52 is fixed to the recess 51g in the main body 51. The outer rotor 52 has a through hole 52h in the center into which the inner rotor 53 is inserted. The inner surface 52S of the through hole 52h has a cross-sectional shape that is a trochoid curve.

[0074] (Inner rotor 53) The inner rotor 53 is inserted into the through hole 52h of the outer rotor 52. The inner rotor 53 is rotatable inside the through hole 52h of the outer rotor 52. The outer surface 53S of the inner rotor 53 has a cross-sectional shape that is a trochoid curve. The number of teeth on the inner rotor 53 is one less than the number of teeth on the outer rotor 52. The inner rotor 53 has a through hole 53h in the center.

[0075] (Thrust plate 54) 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.

[0076] The attachment of the positive displacement pump 50 to the rear muffler 34 will now be described. Figure 7 is a perspective view illustrating the attachment of the positive displacement pump 50 in a rotary compressor 1, which is an example of a rotary compressor according to the first embodiment.

[0077] The rear muffler 34 comprises 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 along the Y-axis direction (vertical direction) in the opposite direction to the Z-axis. The wall portion 34b has an inner surface 34S.

[0078] The positive displacement pump 50 is fitted into the wall portion 34b. Specifically, the positive displacement pump 50 is fitted into the wall portion 34b by fitting the outer surface 51T of the main body 51 of the positive displacement pump 50 with the inner surface 34S of the wall portion 34b. The positive displacement pump 50 may also be fitted into the rear muffler 34 by press-fitting.

[0079] The wall portion 34b has a threaded hole 34s into which a bolt 55 is inserted. The bolt 55 passes through the through hole 51h in the flange portion 51f and is screwed into the threaded hole 34s in the wall portion 34b. By screwing the bolt 55 into the threaded hole 34s, the flange portion 51f is fixed to the wall portion 34b by the bolt 55. By fixing the flange portion 51f to the wall portion 34b by the bolt 55, the positive displacement pump 50 is fixed to the rear muffler 34.

[0080] Furthermore, a gap is formed in the portion where the inner surface 34S and the outer surface 51T of the wall portion 34b are not in contact. Lubricating oil discharged into the internal space 81a of the shaft 81 is discharged into the oil reservoir SP through this gap.

[0081] Next, the operation of the positive displacement pump 50 will be described. Figure 8 is a plan view illustrating the operation of the positive displacement pump 50 in a rotary compressor 1, which is an example of a rotary compressor according to the first embodiment. More specifically, Figure 8 is a plan view showing a top view of the outer rotor 52 and inner rotor 53 in the positive displacement pump 50. When the inner rotor 53 rotates relative to the outer rotor 52 in the direction of the arrowed line R, lubricating oil accumulated in the oil reservoir SP is sucked in range DS. A through hole 51s is connected to range DS. Then, the lubricating oil is discharged in range DE. The lubricating oil is discharged downwards once, then passes through the groove 51d and through the through hole 53h of the inner rotor 53 before being discharged.

[0082] As described above, as the inner rotor 53 rotates relative to the outer rotor 52, lubricating oil is drawn in through the through hole 51s of the main body 51. The drawn-in lubricating oil is then transported as the outer rotor 52 rotates. The transported lubricating oil is then discharged through the through hole 53h of the inner rotor 53 into the internal space 81a of the shaft 81.

[0083] The flow of lubricating oil will be explained in detail. Figure 9 is a cross-sectional view illustrating the flow of lubricating oil in a rotary compressor 1, which is an example of a rotary compressor according to the first embodiment. The lubricating oil accumulated in the oil reservoir SP is sucked in through the through hole 51s, as shown by the dotted line SC with an arrow. The sucked-in lubricating oil is transferred by the rotation of the inner rotor 53 relative to the outer rotor 52. The transferred lubricating oil is then discharged into the inside of the pipe 85 through the groove 51d, as shown by the dotted line DC with an arrow, and discharged into the internal space 81a of the shaft 81. The pipe 85 comprises 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 shown by the dotted line with arrow in Figure 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, cylinder 41, cylinder 42, and upper bearing 32 from the lower bearing oil supply hole 81h1, communication hole 81h2, communication hole 81h3, and upper bearing oil supply hole 81h4, respectively.

[0085] Furthermore, any lubricating oil supplied between the internal space 81a and the pipe 85 that is not supplied to the lower bearing 31, cylinder 41, cylinder 42, and 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 then discharged into the oil reservoir SP through the gap between the rear muffler 34 and the positive displacement pump 50, along the dotted line DR with an arrow shown in Figure 9.

[0086] The method for discharging the lubricating oil discharged into the internal space 81a of the shaft 81 to the oil reservoir SP is not limited to the above example. Figure 10 is a cross-sectional view illustrating the flow of lubricating oil in a first modified example of a rotary compressor 1, which is an example of a rotary compressor according to the first embodiment. The first modified example includes a rear muffler 134 instead of a rear muffler 34. The rear muffler 134 has an opening 134h in its wall portion 134b that communicates with the outside of the wall portion 134b in order to discharge the lubricating oil to the oil reservoir SP. As shown by the dotted line DR with an arrow in Figure 10, the lubricating oil may be discharged to the oil reservoir SP through the opening 134h.

[0087] In the first modified example, the compression section includes a positioning mechanism 171 for positioning the rear muffler 134 with respect to the lower bearing 31. The positioning mechanism 171 is composed of a first connecting portion 31i and a second connecting portion 134p.

[0088] The second connecting portion 134p is provided on the upper part of the rear muffler 134. In other words, the rear muffler 134 has the second connecting portion 134p on its upper part. The second connecting portion 134p is a protrusion that extends upward (towards the +Z side) from the upper surface of the rear muffler 34. The second connecting portion 134p is formed around the shaft 81.

[0089] The first connecting portion 31i and the second connecting portion 134p fit together. By fitting together the first connecting portion 31i and the second connecting portion 134p, they are fixed in place.

[0090] Furthermore, if the rear muffler has an opening, it is not necessary to provide a gap between the rear muffler and the positive displacement pump, as is the case with the rotary compressor 1.

[0091] Furthermore, as shown in Figures 9 and 10, the lower end 81e of the shaft 81 may be positioned at a distance from the thrust plate 54. The distance h is between the lower end 81e of the shaft 81 and the thrust plate 54.

[0092] The lower part of the pipe 85 may be fixed to the inner rotor 53 in order to rotate the inner rotor 53. Alternatively, the lower part of the shaft 81 may be fixed to the inner rotor 53 in order to rotate the inner rotor 53.

[0093] Furthermore, in the rotary compressor according to the first embodiment, the pipe in the internal space of the shaft is not limited to the pipe 85 shown in the above example. Figure 11 is a cross-sectional view of rotary compressor 2, which is a second modification of rotary compressor 1, which is an example of rotary compressor according to the first embodiment. Figure 12 is a cross-sectional view illustrating the flow of lubricating oil in the second modification of rotary compressor 1, which is an example of rotary compressor according to the first embodiment. Figure 13 is a cross-sectional view illustrating the flow of lubricating oil in the second modification of rotary compressor 1, which is an example of rotary compressor according to the first embodiment. In the second modification, pipe 185 is provided instead of pipe 85. Pipe 185 is provided only with a flange portion 85f, excluding the pipe 85p of pipe 85. As shown in the second modification, in the rotary compressor according to the first embodiment, pipe may or may not be present. Furthermore, 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 is equipped with a positive displacement pump, which allows for lubrication without being limited by the oil level in the lubricating oil or the rotational speed of the rotary compressor.

[0095] <Second Embodiment> A rotary compressor according to the second embodiment will now be described. The rotary compressor according to the second embodiment differs from the rotary compressor according to the first embodiment in the details of the positive displacement pump. Figures 14 and 15 are cross-sectional views of a rotary compressor 3, which is an example of a rotary compressor according to the second embodiment. Figure 15 is an enlarged cross-sectional view of the compression section 170 in the rotary compressor 3.

[0096] (Positive displacement pump 150) The positive displacement pump 150 will be described in detail. Figure 16 is an exploded perspective view of a positive displacement pump 150, which is an example of a positive displacement pump in a 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 trochoidal pump.

[0098] The positive displacement pump 150 comprises a main body 151, an outer rotor 152, an inner rotor 153, and a thrust plate 154.

[0099] (Main body 151) The main body 151 will be described in detail. Figure 17 is a bottom view of the main body 151 of a positive displacement pump 150, which is an example of a positive displacement pump in a rotary compressor according to the second embodiment. Figure 18 is a top view of the main body 151 of a positive displacement pump 150, which is an example of a positive displacement pump in a rotary compressor according to the second embodiment.

[0100] The main body 151 has a recess 151g at its upper part in which the outer rotor 152 and inner rotor 153 are housed. The main body 151 also has a through hole 151s that penetrates from the bottom surface 151D, which is the lowest surface, to the bottom surface 151S of the recess 151g. The positive displacement pump 150 sucks the lubricating oil accumulated in the oil reservoir SP through the through hole 151s.

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

[0102] The main body 151 has a flange portion 151f at its upper end that extends in a direction parallel to the XY plane. The flange portion 151f has a through hole 151h through which a bolt 155 passes. The bolt 155 passes through the through hole 151h in the flange portion 151f and is screwed into a threaded hole 34s in the wall portion 34b. By screwing the bolt 155 into the threaded hole 34s, the flange portion 151f is fixed to the wall portion 34b by the bolt 155. By fixing the flange portion 151f to the wall portion 34b by the bolt 155, the positive displacement pump 150 is fixed to the rear muffler 34.

[0103] (Outer rotor 152) The outer rotor 152 is fixed to the recess 151g in the main body 151. The outer rotor 152 has a through hole 152h in the center into which the inner rotor 153 is inserted. The inner surface of the through hole 152h has a cross-sectional shape that is a trochoid curve.

[0104] (Inner rotor 153) The inner rotor 153 is inserted into the through hole 152h of the outer rotor 152. The inner rotor 153 is rotatable inside the through hole 152h of the outer rotor 152. The outer surface of the inner rotor 153 has a cross-sectional shape that is a trochoid curve. The number of teeth on the inner rotor 153 is one less than the number of teeth on the outer rotor 152. The inner rotor 153 has a through hole 153h in the center.

[0105] (Thrust plate 154) The thrust plate 154 is a plate for holding down the inner rotor 153. The thrust plate 154 has a through hole 154h in its center. The thrust plate 154 also has a discharge hole 154t through which lubricating oil is discharged.

[0106] The flow of lubricating oil will be explained in detail. Figure 19 is a cross-sectional view illustrating the flow of lubricating oil in a rotary compressor according to the second embodiment. The lubricating oil accumulated in the oil reservoir SP is sucked in through the through hole 151s, as shown by the dotted line SC with an arrow. The sucked-in lubricating oil is transferred by the rotation of the inner rotor 153 relative to the outer rotor 152. The transferred lubricating oil is then discharged into the internal space 81a of the shaft 81, as shown by the dotted line DC with an arrow.

[0107] Lubricating oil discharged between the internal space 81a of the shaft 81 and the pipe 85 is supplied between the internal space 81a and the pipe 85, as shown by the dotted line with arrow in Figure 15. The lubricating oil supplied between the internal space 81a and the pipe 85 is supplied to the lower bearing 31, cylinder 41, cylinder 42, and upper bearing 32 from the lower bearing oil supply hole 81h1, communication hole 81h2, communication hole 81h3, and upper bearing oil supply hole 81h4, respectively. Any lubricating oil supplied between the internal space 81a and the pipe 85 that is not supplied to the lower bearing 31, cylinder 41, cylinder 42, and upper bearing 32 is discharged into the pipe 85. The lubricating oil discharged into the pipe 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 from the through hole 151t into the oil reservoir SP along the dotted line DR with an arrow shown in Figure 19.

[0109] As the inner rotor 153 rotates relative to the outer rotor 152, lubricating oil is drawn in through the through hole 151s of the main body 151. The drawn-in lubricating oil is then transported as the outer rotor 152 rotates. The transported lubricating oil is then discharged through the discharge hole 154t of the inner rotor 153 into the internal space 81a of the shaft 81.

[0110] Furthermore, in the rotary compressor according to the second embodiment, the pipe in the internal space of the shaft is not limited to the pipe 85 shown in the above example. Figure 20 is a cross-sectional view illustrating the flow of lubricating oil in a modified example of the rotary compressor according to the second embodiment. In this modified example, pipe 185 is provided instead of pipe 85. Pipe 185 has only a flange portion 85f, excluding the pipe 85p of pipe 85. As shown in this modified example, in the rotary compressor according to the second embodiment, the pipe may or may not be present. Also, in the rotary compressor according to the second embodiment, the shape of the pipe is not limited.

[0111] The rotary compressor according to the second embodiment, like the rotary compressor according to the first embodiment, is equipped with a positive displacement pump, allowing for lubrication without being limited by the oil level in the lubricating oil or the rotational speed of the rotary compressor.

[0112] <Modified Positioning Mechanism> Modified positioning mechanisms will now be described. Figure 21 is a cross-sectional view illustrating a modified positioning mechanism 271 in a rotary compressor according to the present disclosure. Figure 21 is a cross-sectional view of Figure 9 in which the positioning mechanism 71 has been changed to the positioning mechanism 271.

[0113] The positioning mechanism 271 has a first connecting portion 231p which is a convex portion in the lower bearing 231 and a second connecting portion 234i which is a concave portion in the rear muffler 234. The positioning mechanism 271 has a first connecting portion 231p which is a convex portion in place of the first connecting portion 31i which is a concave portion. Also, the positioning mechanism 271 has a second connecting portion 234i which is a concave portion in place of the second connecting portion 34p which is a convex portion.

[0114] The lower bearing 231 has the same configuration as the lower bearing 31, except for the first connecting portion 231p. The rear muffler 234 also has the same configuration as the rear muffler 34, except for the second connecting portion 234i.

[0115] The positioning mechanism 271 positions the rear muffler 234 relative to the lower bearing 231. The positioning mechanism 271 is composed of a first connecting portion 231p and a second connecting portion 234i.

[0116] The first connecting portion 231p is provided at the lower part of the lower bearing 231. In other words, the lower bearing 231 has the first connecting portion 231p at its lower part. The first connecting portion 231p is a protrusion that extends downward (towards the -Z side) from the lower surface of the lower bearing 231. The first connecting portion 231p is formed around the shaft 81.

[0117] The second connecting portion 234i is provided on the upper part of the rear muffler 234. In other words, the rear muffler 234 has the second connecting portion 234i on its upper part. The second connecting portion 234i is a recess that is recessed downward (towards the -Z side) from the upper surface of the rear muffler 234. The second connecting portion 234i is formed around the shaft 81.

[0118] The first connecting portion 231p and the second connecting portion 234i fit together. By fitting together the first connecting portion 231p and the second connecting portion 234i, they are fixed to each other.

[0119] Another modification of the positioning mechanism will be described. Figure 22 is a cross-sectional view illustrating a positioning mechanism 371, which is a modification of the positioning mechanism in a rotary compressor according to an embodiment of the present disclosure. Figure 22 is a cross-sectional view of Figure 9 in which the positioning mechanism 71 has been changed to the positioning mechanism 371.

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

[0121] The lower bearing 331 has the same configuration as the lower bearing 31, except for the first insertion portion 331h. The rear muffler 334 also has the same configuration as the rear muffler 34, except for the second insertion portion 334h.

[0122] The positioning mechanism 371 positions the rear muffler 334 relative 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 portion 331h is provided at the lower part of the lower bearing 331. In other words, the lower bearing 331 has the first insertion portion 331h at its lower part. The first insertion portion 331h is a fitting hole that is recessed from the lower surface of the lower bearing 331 toward the upper side (+Z side). Multiple first insertion portions 331h are formed at equal intervals around the shaft 81.

[0124] The second insertion portion 334h is provided on the upper part of the rear muffler 334. In other words, the rear muffler 34 has the second insertion portion 334h on its upper part. The second insertion portion 334h is a fitting hole that is recessed downward (towards the -Z side) from the upper surface of the rear muffler 334. Multiple second insertion portions 334h are formed at equal intervals around the shaft 81.

[0125] The positioning pin 372 is inserted into the corresponding first insertion portion 331h and second insertion portion 334h. By inserting the positioning pin 372 into the corresponding first insertion portion 331h and second insertion portion 334h, the first insertion portion 331h and the second insertion portion 334h are positioned. At least two, i.e., multiple, positioning pins 372, first insertion portion 331h, and second insertion portion 334h are provided.

[0126] <Refrigeration System> A refrigeration system equipped with a rotary compressor according to this embodiment will be described. Figure 23 is a schematic diagram of a refrigeration system 100, which is an example of a refrigeration system equipped with a rotary compressor according to this embodiment.

[0127] The refrigeration system 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 a rotary compressor according to this embodiment.

[0128] First, we will explain the case where the refrigeration system 100 is cooled by the heat exchanger 105. Figure 23 shows the connections when the refrigeration system 100 is cooled by the heat exchanger 105.

[0129] The refrigerant compressed by the compressor 101 is supplied to the heat exchanger 103 through the four-way valve 102. In the heat exchanger 103, the refrigerant supplied to the heat exchanger 103 is cooled by heat exchange with air or the like. The refrigerant cooled in the heat exchanger 103 condenses and liquefies, 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. In the heat exchanger 105, the refrigerant evaporates and vaporizes. The refrigerant discharged from the heat exchanger 105 then returns to the compressor 101 and is compressed again. In the heat exchanger 105, the refrigeration device 100 cools the object by the heat of vaporization caused by the evaporation of the refrigerant.

[0130] Next, we will explain the case where the refrigeration system 100 is heated by the heat exchanger 105. The refrigerant compressed by the compressor 101 is supplied to the heat exchanger 105 through the four-way valve 102. In the heat exchanger 105, the refrigeration system 100 heats the object by supplying the compressed, high-temperature refrigerant. The refrigerant that has undergone heat exchange in the heat exchanger 105 condenses and liquefies, 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. In the heat exchanger 103, the refrigerant evaporates and vaporizes by exchanging heat with air or the like. The refrigerant discharged from the heat exchanger 103 then passes through the four-way valve 102 and returns to the compressor 101 to be compressed again.

[0131] While embodiments have been described above, it will be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. Various modifications and improvements are possible, such as combinations or substitutions with some or all of other embodiments.

[0132] This application claims priority to Basic Patent Application No. 2024-162422, filed with the Japan Patent Office on September 19, 2024, the entire contents of which are incorporated herein by reference.

[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 Section 80 Electric Section 81 Shaft 81a Internal Space 85, 185 Pipe 100 Refrigeration System 101 Compressor 103, 105 Heat Exchanger 104 Expansion Valve

Claims

1. A rotary compressor (1) comprising: a casing (11); cylinders (41, 42) disposed inside the casing (11); pistons (61, 62) that rotate eccentrically inside the cylinders (41, 42); a hollow shaft (81) connected to the pistons (61, 62) and having an internal space (81a); an upper bearing (32) disposed above the cylinders (41, 42) and supporting the shaft (81); a lower bearing (31) disposed below the cylinders (41, 42) and supporting the shaft (81); a rear muffler (34) disposed below the lower bearing (31); and positive displacement pumps (50, 150) attached to the rear muffler (34) for discharging oil into the internal space (81a).

2. The rotary compressor (1) according to claim 1, wherein a positioning mechanism (71, 171, 271, 371) is provided for positioning the rear muffler (34, 234, 334) with respect to the lower bearings (31, 231, 331).

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

4. A rotary compressor (1) according to claim 2, having a plurality of positioning pins (372), the lower bearing (331) having a plurality of first insertion portions (331h) through which the plurality of positioning pins (372) are inserted, the rear muffler (334) having a plurality of second insertion portions (334h) through which the plurality of positioning pins (372) are inserted, and 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).

5. The rotary compressor (1) according to any one of claims 1 to 4, wherein the positive displacement pump (50, 150) has flange portions (51f, 151f) at its upper part, and the flange portions (51f, 151f) are fixed to the rear muffler (34) by bolts (55, 155).

6. The rotary compressor (1) according to any one of claims 1 to 4, wherein the rear muffler (34) is provided with a wall portion (34b) extending in the vertical direction, and the positive displacement pumps (50, 150) are fixed to the wall portion (34b) by bolts (55, 155).

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

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

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

10. The rotary compressor (1) according to any one of claims 1 to 9, wherein the lower surface of the eccentric portion of the shaft slides against the 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) is equipped with thrust plates (54, 154), and the lower end of the shaft (81) is separated from the thrust plates (54, 154).

13. A rotary compressor (1) according to claim 11 or claim 12, wherein pipes (85, 185) are arranged in the internal space (81a) at a distance from the inner wall of the shaft (81), the trochoid pump (50, 150) is equipped with an inner rotor (53, 153), and the lower part of the pipes (85, 185) is fixed to the inner rotor (53, 153).

14. The rotary compressor (1) according to claim 11 or claim 12, wherein the trochoid pump (50, 150) comprises inner rotors (53, 153), and the lower part of the shaft (81) is fixed to the inner rotors (53, 153).

15. A refrigeration system (100) comprising a rotary compressor (1) according to any one of claims 1 to 14.

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