Rotary compressor and refrigeration device

Abstract

In a rotary compressor, when viewed in an axial direction, a region that overlaps a cylinder chamber (S1) between a blade (38) and a thin portion (52) is defined as a first region (77); a region that overlaps the cylinder chamber (S1) between the blade (38) and a suction port is defined as a second region (78); and when a piston (35) is located at a bottom dead center, a gap (CR1) between part of an outer edge of the piston (35) that corresponds to the first region (77) and part of a closing member (50) that corresponds to the first region (77) is larger than a gap (CR2) between part of the piston (35) that corresponds to the second region (78) and part of the closing member (50) that corresponds to the second region (78).

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 eccentrically rotates a piston in the cylinder in order to compress gas in a compression chamber formed in a cylinder. In general, the rotary compressor has a blade for partitioning the compression chamber.BACKGROUND ART

[0002] A conventional rotary compressor is known which includes an annular piston that turns along the inner surface of a cylinder chamber of a cylinder, a blade that is coupled with the piston, and closing members that are disposed on each of the end surface of the piston and both the end surfaces of the cylinder in the axial direction. In this rotary compressor, a refrigerant sucked into the cylinder chamber through a suction hole is compressed by turning of the piston, and then is discharged through a discharge port.

[0003] For example, a rotary compressor of Patent Document 1 includes a first part which is comprised of part of a piston that is near a blade and the blade and a second part which is comprised of part of the piston that excludes the first portion, where the second portion more protrudes than the first portion.CITATION LISTPATENT DOCUMENT

[0004] Patent Document 1: Japanese Unexamined Patent Publication No. 2017-15064SUMMARY OF THE INVENTIONTECHNICAL PROBLEM

[0005] In a rotary compressor, the gap between a piston and a closing member is designed to reduce seizing between the piston and the closing member while allowing the piston to perform turning operation smoothly.

[0006] In the rotary compressor of Patent Document 1, the gap between the piston and the closing member is designed to reduce seizing between the piston and the closing member near the suction hole where the amount of thermal expansion of the cylinder is small. However, upon intensive research, the inventors of the present application have found that in order to reduce seizing between the piston and the closing member, it is necessary to consider not only the influence due to heat but the pressure difference between the inside and outside of the cylinder chamber.

[0007] An object of the present disclosure is to provide a rotary compressor that can reduce seizing between a piston and a closing member.SOLUTION TO THE PROBLEM

[0008] A first aspect of the technique disclosed herein is directed to a rotary compressor. The rotary compressor includes: a cylinder (31, 41, 331, 341, 431) in which a cylinder chamber (S1, S2) is provided; a piston (35, 45, 235, 245) configured not to rotate but to turn along an inner surface of the cylinder chamber (S1, S2); a rotary shaft (90) configured to turn the piston (35, 45, 235, 245); a blade (38, 48) coupled with the piston (35, 45, 235, 245) and dividing the cylinder chamber (S1, S2) into a suction space (71, 75) and a discharge space (72, 76); a suction port (17, 18, 317, 318, 417) configured to supply a refrigerant to the suction space (71, 75); and a closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) configured to close both end portions of the cylinder chamber (S1, S2) in an axial direction of the rotary shaft (90), wherein at a position of the piston (35, 45, 235, 245), the rotary shaft (90) includes an eccentric portion (91, 92) that is eccentric with respect to a center (X) of the rotary shaft (90), the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) includes a discharge port (51, 57, 251, 257) communicating with the discharge space (72, 76) and discharging a compressed refrigerant from the discharge space (72, 76), and a thin portion (52, 58, 252, 258) formed in an area including a surrounding area of the discharge port (51, 57, 251, 257) and having a smaller thickness in the axial direction than another part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456), when viewed in the axial direction, a line segment that connects a first point (P1), one of the intersections between an outer edge of the thin portion (52, 58, 252, 258) and an inner edge of the cylinder (31, 41) that is closer to a bottom dead center of the piston (35, 45, 235, 245), with the center (X) of the rotary shaft (90) is defined as a first line segment (L1), a line segment that connects a second point (P2), one of the intersections between the suction port (17, 18, 317, 318, 417) and the inner edge of the cylinder (31, 41) that is closer to the bottom dead center of the piston (35, 45, 235, 245), with the center (X) of the rotary shaft (90) is defined as a second line segment (L2), a region that overlaps the cylinder chamber (S1, S2) between the blade (38, 48) and the first line segment (L1) when the piston (35, 45, 235, 245) is located at the bottom dead center is defined as a first region (77, 277), a region that overlaps the cylinder chamber (S1, S2) between the blade (38, 48) and the second line segment (L2) when the piston (35, 45, 235, 245) is located at the bottom dead center is defined as a second region (78, 278), and when the piston (35, 45, 235, 245) is located at the bottom dead center, a gap (CR1) between part of an outer edge of the piston (35, 45, 235, 245) that corresponds to the first region (77, 277) and part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that corresponds to the first region (77, 277) is larger than a gap (CR2) between part of the piston (35, 45, 235, 245) that corresponds to the second region (78, 278) and part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that corresponds to the second region (78, 278).

[0009] In the first aspect, near the discharge port (51, 57, 251, 257), the refrigerant tends to have a higher temperature, and the pressure outside the cylinder chamber (S1, S2) tends to become higher than the pressure inside the cylinder chamber (S1, S2). Thus, due to the pressure difference, the piston (35, 45, 235, 245) may thermally expand. By the gap between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) being widened in the first region (77, 277) near the discharge port (51, 57, 251, 257), the rotary compressor can reduce seizing between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456).

[0010] A second aspect of the technique disclosed herein is an embodiment of the first aspect. In the second aspect, part of the piston (35, 45, 235, 245) that corresponds to the first region (77, 277) has a first recessed portion (81) which is a surface recessed in the axial direction compared to the part of the piston (35, 45, 235, 245) that corresponds to the second region (78, 278).

[0011] In the second aspect, the gap between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) can be widened by simple processing. The rotary compressor can reduce seizing between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456).

[0012] A third aspect of the technique disclosed herein is an embodiment of the second aspect. In the third aspect, when viewed in the axial direction, the first recessed portion (81) is located so as to include an area defined by 90° toward the discharge port (51, 57, 251, 257) about a center (DC1, DC2) of the eccentric portion (91, 92) with respect to a center line (CL) of the blade (38, 48) passing through the center (DC1, DC2) of the eccentric portion (91, 92).

[0013] In the third aspect, the first recessed portion (81) is located in the area included in part of the piston (35, 45, 235, 245) that is near the discharge port (51, 57, 251, 257). The rotary compressor can reduce seizing between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456).

[0014] A fourth aspect of the technique disclosed herein is an embodiment of the second or third aspect. In the fourth aspect, the first recessed portion (81) is located on only a surface (35a, 45b) among surfaces (35a, 35b, 45a, 45b) of the piston (35, 45, 235, 245) in the axial direction that is closer to the discharge port (51, 57, 251, 257).

[0015] In the fourth aspect, it is possible to narrow the area in which the gap between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) can be widened. While enhancing the efficiency of compression, the rotary compressor can reduce seizing between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456).

[0016] A fifth aspect of the technique disclosed herein is an embodiment of the second or third aspect. In the fifth aspect, the first recessed portion (81) is located on a surface (35a, 45b) among surfaces (35a, 35b, 45a, 45b) of the piston (35, 45, 235, 245) in the axial direction that is closer to the discharge port (51, 57, 251, 257), and a surface (35b, 45a) among the surfaces (35a, 35b, 45a, 45b) of the piston (35, 45, 235, 245) in the axial direction that is farther from the discharge port (51, 57, 251, 257) has a second recessed portion (82) which is located at a position that overlaps the first recessed portion (81) when viewed in the axial direction and which is recessed in an opposite direction to the first recessed portion (81).

[0017] In the fifth aspect, it is possible to reduce seizing between each of the closing members (50, 56, 250, 256, 350, 355, 356, 450, 456) located on both sides of the cylinder (31, 41, 331, 341, 431) in the axial direction and the piston (35, 45, 235, 245).

[0018] A sixth aspect of the technique disclosed herein is an embodiment of any one of the second to fifth aspects. In the sixth aspect, when the piston (35, 45, 235, 245) is located at a top dead center, part of the first recessed portion (81) that is closer to the discharge port (51, 57, 251, 257) in a circumferential direction of the piston (35, 45, 235, 245) is deeper relative to part of the piston (35, 45, 235, 245) that is on a suction side.

[0019] In the sixth aspect, it is possible to narrow the area in which the gap between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) can be widened. While enhancing the efficiency of compression, the rotary compressor can reduce seizing between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456).

[0020] A seventh aspect of the technique disclosed herein is an embodiment of any one of the second to sixth aspects. In the seventh aspect, the piston (35, 45, 235, 245) has a third recessed portion (83) which is located in part of the piston (35, 45, 235, 245) that is different in the circumferential direction from part on which the first recessed portion (81) is located and which is a surface recessed in the axial direction.

[0021] In the seventh aspect, the rotary compressor can reduce seizing between the piston and the closing member even if there is another part that is likely to be deformed than part of the piston (35, 45, 235, 245) that is near the discharge port (51, 57, 251, 257).

[0022] An eighth aspect of the technique disclosed herein is an embodiment of any one of the first to seventh aspects. In the eighth aspect, a gap between at least part of the blade (38, 48) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) is larger than a gap (CR2) between part of the piston (35, 45, 235, 245) that is on the suction side and part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that is on the suction side.

[0023] In the eighth aspect, the rotary compressor can further reduce seizing of the blade (38, 48) even if the blade (38, 48) is deformed by a high-temperature and high-pressure refrigerant.

[0024] A ninth aspect of the technique disclosed herein is an embodiment of the eighth aspect. In the ninth aspect, the at least part of the blade (38, 48) is part which is located close to the discharge port (51, 57, 251, 257) and which is part of a surface (38b, 48c) that is recessed in the axial direction compared to part of the blade (38, 48) that is closer to the suction port (17, 18, 317, 318, 417).

[0025] In the ninth aspect, the part that is likely to thermally expand is recessed with respect to the part that is less likely to thermally expand, whereby while enhancing the performance of partitioning the blade (38, 48), the rotary compressor can reduce seizing of the blade (38, 48).

[0026] A tenth aspect of the technique disclosed herein is an embodiment of the eighth or ninth aspect. In the tenth aspect, the at least part of the blade (38, 48) that is closer to a coupling portion between the piston (35, 45, 235, 245) and the blade (38, 48) is deeper relative to part of the piston (35, 45, 235, 245) that is on a suction side.

[0027] In the tenth aspect, it is possible to narrow the area in which the gap between the blade (38, 48) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) can be widened. While enhancing the performance of partitioning the blade (38, 48), the rotary compressor can reduce seizing of the blade (38, 48).

[0028] An eleventh aspect of the technique disclosed herein is an embodiment of any one of the first to tenth aspects. In the eleventh aspect, part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that corresponds to the first region (77, 277) has a fourth recessed portion (252a, 258a) which is a surface closer to the cylinder chamber (S1, S2) and recessed compared to part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that corresponds to the second region (78, 278), and the fourth recessed portion (252a, 258a) is located only in a part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that is around the discharge port (51, 57, 251, 257).

[0029] In the eleventh aspect, it is possible to narrow the area in which the gap between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) can be widened. While enhancing the efficiency of compression, the rotary compressor can reduce seizing between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456).

[0030] A twelfth aspect of the technique disclosed herein is an embodiment of any one of the first to eleventh aspects. In the twelfth aspect, the refrigerant is carbon dioxide.

[0031] In the twelfth aspect, since carbon dioxide is more likely to create a high pressure compared to other refrigerants, the pressure tends to be high near the discharge port (51, 57, 251, 257), and part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that is near the discharge port (51, 57, 251, 257) is likely to be deformed. The rotary compressor can reduce seizing between the piston (35, 45, 235, 245) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) even if carbon dioxide is used.

[0032] A thirteenth aspect of the technique disclosed herein is directed to a refrigeration apparatus. The refrigeration apparatus includes the rotary compressor (1, 201, 301, 401) of any one of the first to twelfth aspects.BRIEF DESCRIPTION OF THE DRAWINGS

[0033] [FIG. 1] FIG. 1 is a piping system diagram of a refrigeration apparatus including a rotary compressor according to a first embodiment. [FIG. 2] FIG. 2 is a longitudinal sectional view of the rotary compressor. [FIG. 3] FIG. 3 is a lateral sectional view of a first cylinder. [FIG. 4] FIG. 4 is a lateral sectional view according to a second cylinder. [FIG. 5] FIG. 5 is a sectional view taken along line IV-IV in FIG. 3. [FIG. 6] FIG. 6 shows a rear head as viewed in the axial direction from an internal space. [FIG. 7] FIG. 7 shows operation of a compression mechanism. [FIG. 8] FIG. 8 shows a positional relationship between a first recessed portion and a discharge port. [FIG. 9] FIG. 9 is a perspective view of a first piston. [FIG. 10A] FIG. 10A shows the first piston as viewed in the radial direction. [FIG. 10B] FIG. 10B shows the second piston as viewed in the radial direction. [FIG. 11] FIG. 11 is a sectional view of a gap between the piston and a front head. [FIG. 12] FIG. 12 shows a piston as viewed in the radial direction according to a first variation. [FIG. 13] FIG. 13 is a perspective view of a piston according to a second variation. [FIG. 14] FIG. 14 shows a positional relationship between a first recessed portion of the piston and a discharge port according to the second variation. [FIG. 15] FIG. 15 is a perspective view of a piston according to a third variation. [FIG. 16] FIG. 16 is a perspective view of a piston according to a fourth variation. [FIG. 17] FIG. 17 is a perspective view of a piston according to a fifth variation. [FIG. 18] FIG. 18 is a sectional view taken along line XVIII-XVIII in FIG. 17. [FIG. 19] FIG. 19 is a sectional view of part of a rotary compressor that is near a first discharge port according to a second embodiment. [FIG. 20] FIG. 20 is a sectional view of part of the rotary compressor that is near a second discharge port according to the second embodiment. [FIG. 21] FIG. 21 is a longitudinal sectional view of a rotary compressor with two suction pipes. [FIG. 22] FIG. 22 is a longitudinal sectional view of a rotary compressor with a single-cylinder compression mechanism. DESCRIPTION OF EMBODIMENTS

[0034] Embodiments of the present disclosure will be described in detail below with reference to the drawings. The present disclosure is not limited to the embodiments shown below, and various changes can be made within the scope without departing from the technical concept of the present disclosure. Since each of the drawings is intended to illustrate the present disclosure conceptually, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for the sake of ease of understanding. In the following description, unless otherwise specified, the "axial direction" indicates the direction in which the rotation axis extends, the "radial direction" indicates the direction which extends radially from the rotation axis, and the "circumferential direction" indicates the circumferential direction which extends around the rotation axis. The terms "top" and "bottom" refer to the directions of a rotary compressor (1) in front view. Some drawings may be illustrated without hatching for the sake of easy understanding of the description.<First Embodiment>(1) Refrigeration Apparatus

[0035] FIG. 1 shows a refrigeration apparatus (100) including a rotary compressor (1) according to a first embodiment. In the following, the rotary compressor (1) may be simply referred to as a compressor (1). The refrigeration apparatus (100) is an air conditioner that conditions air in an indoor space, for example. The refrigeration apparatus (100) has an outdoor unit (7) disposed outdoors and an indoor unit (8) disposed indoors. The outdoor unit (7) includes the compressor (1), an accumulator (2), a four-way switching valve (3), an outdoor heat exchanger (4a), an expansion valve (5), and an economizer heat exchanger (4b). The indoor unit (8) includes an indoor heat exchanger (6). The outdoor unit (7) and the indoor unit (8) are connected via a connection pipe (9a) to form a refrigerant circuit (9).

[0036] The compressor (1) of this embodiment is a compressor with a blade (38, 48) that eccentrically rotates while being connected to a certain position of an outer peripheral portion of a piston (35, 45), and this compressor is a so-called swing-type compressor where the blade (38, 48) and the piston (35, 45) are integrated together. The compressor (1) compresses a low-pressure gas refrigerant into a high-pressure gas refrigerant. The compressor (1) is driven by a compressor motor. The compressor (1) is supplied with part of an intermediate-pressure refrigerant flowing from the outdoor heat exchanger (4a) toward the expansion valve (5) in order to perform intermediate injection. The intermediate pressure is a predetermined pressure between the pressure of a gas refrigerant sucked into the compressor (1) (the low pressure) and the pressure of a gas refrigerant discharged from the compressor (1) (the high pressure). The refrigerant is not particularly limited but may be carbon dioxide (CO 2 ), for example.

[0037] The four-way switching valve (3) switches a connection state of an internal pipe of the outdoor unit (7). When the refrigeration apparatus (100) performs a cooling operation, the four-way switching valve (3) turns to the connection state indicated by the broken lines in FIG. 1. When the refrigeration apparatus (100) performs a heating operation, the four-way switching valve (3) turns to the connection state indicated by the solid lines in FIG. 1.

[0038] The outdoor heat exchanger (4a) exchanges heat between the refrigerant circulating in the refrigerant circuit (9) and the outdoor air. The outdoor heat exchanger (4a) has a refrigerant flow path through which a refrigerant flows, and a heat transfer fin that is in contact with the outdoor air. The outdoor heat exchanger (4a) functions as a radiator (a condenser) for a refrigerant during the cooling operation, and functions as an absorber (an evaporator) for a refrigerant during the heating operation.

[0039] The expansion valve (5) is an electric valve or an electromagnetic valve of which the opening degree is adjustable. The expansion valve (5) decompresses a refrigerant flowing through the internal pipe of the outdoor unit (7). The expansion valve (5) controls the flow rate of a refrigerant flowing through the internal pipe of the outdoor unit (7).

[0040] The accumulator (2) is disposed in a suction-side pipe of the compressor (1). The accumulator (2) separates a gas-liquid mixture refrigerant flowing through the refrigerant circuit into a gas refrigerant and a liquid refrigerant, and stores the liquid refrigerant. The gas refrigerant separated in the accumulator (2) is sent to a suction port of the compressor (1).

[0041] The economizer heat exchanger (4b) is disposed between the outdoor heat exchanger (4a) and the expansion valve (5). The economizer heat exchanger (4b) exchanges heat between a refrigerant flowing from the outdoor heat exchanger (4a) toward the expansion valve (5) and a refrigerant flowing through an economizer pipe (9b). The economizer pipe (9b) is a pipe branched between the economizer heat exchanger (4b) and the expansion valve (5) in the refrigerant circuit (9) and connected to an injection pipe (9c). An economizer valve (9d) is attached to the economizer pipe (9b). The refrigerant flowing through the economizer pipe (9b) is decompressed by the economizer valve (9d), and then exchanges heat in the economizer heat exchanger (4b) with the refrigerant flowing from the outdoor heat exchanger (4a) toward the expansion valve (5). The refrigerant flowing from the outdoor heat exchanger (4a) toward the expansion valve (5) and the refrigerant having exchanged heat in the economizer heat exchanger (4b) are supplied to the injection pipe (9c) as intermediate-pressure refrigerants.

[0042] The refrigeration apparatus (100) includes the refrigerant circuit (9). The compressor (1), the four-way switching valve (3), the outdoor heat exchanger (4a), the expansion valve (5), the indoor heat exchanger (6), and the economizer heat exchanger (4b) are connected to the refrigerant circuit (9). The refrigerant flows through the refrigerant circuit (9) to create a refrigeration cycle.

[0043] The refrigeration apparatus (100) performs the heating operation and the cooling operation by switching the four-way switching valve (3). In the cooling operation, a first refrigeration cycle is performed. Specifically, in the connection state indicated by the broken lines in FIG. 1, the indoor heat exchanger (6) functions as an evaporator, and the outdoor heat exchanger (4a) functions as a radiator. In the heating operation, a second refrigeration cycle is performed. Specifically, in the connection state indicated by the solid lines in FIG. 1, the indoor heat exchanger (6) functions as a radiator, and the outdoor heat exchanger (4a) functions as an evaporator.(2) Rotary Compressor

[0044] As shown in FIG. 2, the compressor (1) includes a closed container (10), an electric motor (20), and a compression mechanism (30). The electric motor (20) and the compression mechanism (30) are housed in the closed container (10). The compressor (1) is a so-called high-pressure dome-type compressor where the refrigerant compressed in the compression mechanism (30) is discharged into an internal space (R) of the closed container (10) so that the pressure in the internal space (R) becomes high.(2-1) Rotary Compressor

[0045] The closed container (10) is vertically long. Specifically, the closed container (10) includes a barrel portion (11) formed in a cylindrical shape and extending in the top-bottom direction, an upper lid portion (12) closing the upper end of the barrel portion (11), and a lower lid portion (13) closing the lower end of the barrel portion (11). A discharge pipe (15) is inserted into an upper portion of the barrel portion (11). A suction pipe (14) is disposed in a lower portion of the barrel portion (11).(2-2) Electric Motor

[0046] The electric motor (20) is housed in the closed container (10). The electric motor (20) drives the compression mechanism (30). The electric motor (20) is disposed above a mounting plate (54). The electric motor (20) has a stator (21) formed in a tubular shape along the inner peripheral surface of the barrel portion (11), and a rotor (22) disposed inside the stator (21).(2-3) Rotary Shaft

[0047] A rotary shaft (90) is disposed so as to extend in the top-bottom direction in the closed container (10). The rotary shaft (90) is driven by the electric motor (20). An upper portion of the rotary shaft (90) is coupled to the rotor (22) of the electric motor (20).

[0048] A lower portion of the rotary shaft (90) has an upper shaft portion (90a), a first eccentric portion (91), an intermediate shaft portion (90b), a second eccentric portion (92), and a lower shaft portion (90c) in sequence from top to bottom. The upper shaft portion (90a), the first eccentric portion (91), the intermediate shaft portion (90b), the second eccentric portion (92), and the lower shaft portion (90c) are integrated together.

[0049] The first eccentric portion (91) and the second eccentric portion (92) are eccentric with respect to the axis of the rotary shaft (90). The first eccentric portion (91) and the second eccentric portion (92) have larger diameters than the upper shaft portion (90a), the intermediate shaft portion (90b), and the lower shaft portion (90c). The eccentric direction of the first eccentric portion (91) with respect to the rotation axis of the rotary shaft (90) is different by 180° from the eccentric direction of the second eccentric portion (92) with respect to the rotation axis of the rotary shaft (90).

[0050] The intermediate shaft portion (90b) is disposed between the first eccentric portion (91) and the second eccentric portion (92). The intermediate shaft portion (90b) couples the first eccentric portion (91) and the second eccentric portion (92).(2-4) Compression Mechanism

[0051] As shown in FIG. 2, the compression mechanism (30) is housed in the closed container (10). The compression mechanism (30) compresses a sucked refrigerant and discharges a compressed refrigerant to the internal space (R) of the closed container (10). The compression mechanism (30) is fixed to the mounting plate (54) fixed to the inner peripheral surface of the barrel portion (11). Specifically, the compression mechanism (30) is disposed on the lower surface of the mounting plate (54). The compression mechanism (30) has two cylinders. The compression mechanism (30) includes the rotary shaft (90), a front head (50), a first cylinder (31), the first piston (35), the first blade (38), a middle plate (55), a second cylinder (41), the second piston (45), the second blade (48), and a rear head (56). The front head (50), the first cylinder (31), the middle plate (55), the second cylinder (41), and the rear head (56) are fixed by a plurality of through bolts (B) in order not to move relative to each other.(2-4-1) Cylinder

[0052] As shown in FIGS. 2 to 4, the first cylinder (31) and the second cylinder (41) are thick disk-shaped members. The first cylinder (31) and the second cylinder (41) include a cylinder bore (32, 42), a blade housing hole (33, 43), a suction port (17, 18), an injection passage (61, 62), and an injection port (63, 64).

[0053] The cylinder bore (32, 42) is a circular hole penetrating the cylinder (31, 41) in the thickness direction. The cylinder bore (32, 42) is formed in a center portion of the cylinder (31, 41). The first cylinder bore (32) of the first cylinder (31) houses the first piston (35). The second cylinder bore (42) of the second cylinder (41) houses the second piston (45).

[0054] In the first cylinder (31), a first cylinder chamber (S1) is formed between the wall surface of the first cylinder bore (32) and the first piston (35). In the second cylinder (41), a second cylinder chamber (S2) is formed between the wall surface of the second cylinder bore (42) and the second piston (45).

[0055] The blade housing hole (33, 43) is a hole extending from the inner peripheral surface of the cylinder (31, 41) (i.e., the outer edge of the cylinder bore (32, 42)) toward the outside of the cylinder (31, 41) in the radial direction. The blade housing hole (33, 43) penetrates the cylinder (31, 41) in the thickness direction. The first blade housing hole (33) of the first cylinder (31) houses the first blade (38). The second blade housing hole (43) of the second cylinder (41) houses the second blade (48).

[0056] The first cylinder (31) has a first passage (16a) as part of a suction passage (16). The first passage (16a) is a hole having a bottom and extending in the thickness direction of the first cylinder (31). The first passage (16a) is disposed to the right side of the first blade housing hole (33) in FIG. 3. The second cylinder (41) has a second passage (16b) as part of the suction passage (16). The second passage (16b) penetrates the second cylinder (41) in the thickness direction. The second passage (16b) is disposed to the right side of the second blade housing hole (43) in FIG. 4.

[0057] The suction port (17, 18) extends from the suction passage (16) toward the cylinder chamber (S1, S2). The first suction port (17) of the first cylinder (31) extends from the first passage (16a) toward the first cylinder chamber (S1). The second suction port (18) of the second cylinder (41) extends from the second passage (16b) toward the second cylinder chamber (S2). The suction port (17, 18) extends toward the cylinder chamber (S1, S2) so as to be closer to the blade housing hole (33, 43) than the suction passage (16) is.

[0058] The injection passage (61, 62) is a passage for supplying a refrigerant to the cylinder chamber (S1, S2) separately from the suction passage (16). The first injection passage (61) of the first cylinder (31) is disposed to the left side of the first blade housing hole (33) in FIG. 3. That is, the first injection passage (61) of the first cylinder (31) is disposed opposite to the first passage (16a) with the first blade housing hole (33) sandwiched therebetween. The second injection passage (62) of the second cylinder (41) is disposed to the left side of the second blade housing hole (43) in FIG. 4. That is, the second injection passage (62) of the second cylinder (41) is disposed opposite to the second passage (16b) with the second blade housing hole (43) sandwiched therebetween.

[0059] The injection port (63, 64) extends from the injection passage (61, 62) toward the cylinder chamber (S1, S2). The injection port (63, 64) extends toward the cylinder chamber (S1, S2) so as to be closer to the blade housing hole (33, 43) than the injection passage (61, 62) is.(2-4-2) Piston

[0060] The first piston (35) is housed in the first cylinder (31). The first piston (35) turns inside the first cylinder chamber (S1). The first piston (35) slides on both the front head (50) and the middle plate (55).

[0061] The first piston (35) is formed in an annular shape centered on the center (DC1) of the first eccentric portion (91). The first piston (35) is formed in a cylindrical shape that is slightly thick. The first eccentric portion (91) of the rotary shaft (90) is inserted into the first piston (35). The first piston (35) turns along the inner peripheral surface of the first cylinder chamber (S1) of the first cylinder (31) as the first eccentric portion (91) rotates.

[0062] The second piston (45) is a member identical in shape, dimension, and material to the first piston (35). The first piston (35) and the second piston (45) are disposed inversely to each other in the top-bottom direction.

[0063] The second piston (45) is housed in the second cylinder (41). The second piston (45) turns inside the second cylinder chamber (S2). The second piston (45) slides on both the rear head (56) and the middle plate (55).

[0064] The second piston (45) is formed in an annular shape centered on the center (DC2) of the second eccentric portion (92). The second piston (45) is formed in a cylindrical shape that is slightly thick. The second eccentric portion (92) of the rotary shaft (90) is inserted into the second piston (45). The second piston (45) turns along the inner peripheral surface of the second cylinder chamber (S2) of the second cylinder (41) as the second eccentric portion (92) rotates.(2-4-3) Blade

[0065] As shown in FIGS. 3 and 4, the first blade (38) and the second blade (48) are rectangular flat plate members that are slightly thick. The first blade (38) is integrated with the first piston (35). The second blade (48) is integrated with the second piston (45). The blade (38, 48) extends outward in the radial direction from the outer peripheral surface of the piston (35, 45).

[0066] The first blade (38) is fitted in the first blade housing hole (33). The first blade (38) is sandwiched from both sides between a pair of first bushes (70) provided in the first cylinder (31). The first blade (38) integrated with the first piston (35) is supported by the first cylinder (31) via the first bushes (70) so as to be freely swingable and freely movable back and forth.

[0067] The first blade (38) divides the first cylinder chamber (S1) into a first suction space (71) and a first discharge space (72). The first blade (38) restricts the first piston (35) from rotating when the first piston (35) is turning. Accordingly, the first piston (35) does not rotate but turns along the inner surface of the first cylinder chamber (S1).

[0068] The second blade (48) is fitted in the second blade housing hole (43). The second blade (48) is sandwiched from both sides between a pair of second bushes (74) provided in the second cylinder (41). The second blade (48) integrated with the second piston (45) is supported by the second cylinder (41) via the second bushes (74) so as to be freely swingable and freely movable back and forth.

[0069] The second blade (48) divides the second cylinder chamber (S2) into a second suction space (75) and a second discharge space (76). The second blade (48) restricts the second piston (45) from rotating when the second piston (45) is turning. Accordingly, the second piston (45) does not rotate but turns along the inner surface of the second cylinder chamber (S2).(2-4-4) Front Head

[0070] As shown in FIG. 2, the front head (50) closes an end portion of the first cylinder (31) in the axial direction. Specifically, the front head (50) closes the upper end surface of the first cylinder (31) (the surface close to the electric motor (20)). The front head (50) is an example of a closing member of the present disclosure. The front head (50) includes a first body portion (50a) and an upper bearing portion (50b). The first body portion (50a) and the upper bearing portion (50b) are integrated together.

[0071] The first body portion (50a) is formed in a substantially circular thick plate shape. The lower surface of the first body portion (50a) is in close contact with the upper end surface of the first cylinder (31). The upper bearing portion (50b) is formed in a cylindrical shape extending from the first body portion (50a) toward the electric motor (20) (or toward the upper side in FIG. 2). The upper bearing portion (50b) is disposed in a center portion of the first body portion (50a). The upper bearing portion (50b) rotatably supports the upper shaft portion (90a) of the rotary shaft (90).

[0072] As shown in FIG. 5, the first body portion (50a) has a first discharge port (51). The first discharge port (51) penetrates the first body portion (50a) in the thickness direction. The first discharge port (51) allows the internal space (R) and the first discharge space (72) to communicate with each other.

[0073] Part of the first body portion (50a) that is around the first discharge port (51) is a first thin portion (52) that is thinner in the axial direction than the other part of the first body portion (50a). Part of the first thin portion (52) that is continuous with the first discharge port (51) is slightly thicker compared to the other part of the first thin portion (52).

[0074] The first discharge port (51) is provided with a first discharge valve (53). The first discharge valve (53) is disposed so as to cover the first discharge port (51). The first discharge valve (53) is released from the first discharge port (51) if the pressure of a refrigerant in the first discharge space (72) is more than or equal to a predetermined value. The refrigerant is discharged from the first discharge space (72) to the internal space (R) through the first discharge port (51) when the first discharge valve (53) is released from the first discharge port (51). The first discharge valve (53) covers the first discharge port (51) again after the refrigerant is discharged to the internal space (R).(2-4-5) Middle Plate

[0075] As shown in FIG. 2, the middle plate (55) is sandwiched in the axial direction between the first cylinder (31) and the second cylinder (41). The middle plate (55) closes an end portion of the first cylinder (31) in the axial direction and an end portion of the second cylinder (41) in the axial direction. Specifically, the middle plate (55) closes the lower end surface of the first cylinder (31) and the upper end surface of the second cylinder (41). The middle plate (55) is an example of the closing member of the present disclosure.

[0076] A center hole penetrating the middle plate (55) in the axial direction is formed in a center portion of the middle plate (55). The intermediate shaft portion (90b) of the rotary shaft (90) is inserted into the center hole.

[0077] The middle plate (55) has an intermediate passage (16c) as part of the suction passage (16). The intermediate passage (16c) penetrates the middle plate (55) in the axial direction. The intermediate passage (16c) allows the first passage (16a) and the second passage (16b) to communicate with each other.

[0078] Although not shown in detail, the middle plate (55) has a passage which allows the first injection passage (61) and the second injection passage (62) to communicate with each other.(2-4-6) Rear Head

[0079] As shown in FIG. 2, the rear head (56) closes an end portion of the second cylinder (41) in the axial direction. Specifically, the rear head (56) closes the lower end surface of the second cylinder (41) (the surface opposite to the electric motor (20)). The rear head (56) is an example of the closing member of the present disclosure. The rear head (56) includes a second body portion (56a), a lower bearing portion (56b), and an extension portion (56c). The second body portion (56a) and the lower bearing portion (56b) form a single member.

[0080] As shown in FIG. 6, the second body portion (56a) is formed in a substantially circular thick plate shape. The lower surface of the second body portion (56a) is in close contact with the lower end surface of the second cylinder (41). The lower bearing portion (56b) is formed in a cylindrical shape extending from the second body portion (56a) toward the opposite side to the second cylinder (41) (or toward the lower side in FIG. 2). The lower bearing portion (56b) is disposed in a center portion of the second body portion (56a). The lower bearing portion (56b) rotatably supports the lower shaft portion (90c) of the rotary shaft (90).

[0081] The extension portion (56c) extends outward in the radial direction from the second body portion (56a). The extension portion (56c) has a first insertion hole (19) into which the suction pipe (14) is inserted and a second insertion hole (60) into which an injection pipe (not shown) is inserted. The first insertion hole (19) and the second insertion hole (60) each extend in the radial direction.

[0082] A lower passage (16d) as part of the suction passage (16) extends from the first insertion hole (19). The lower passage (16d) extends upward in the axial direction from the end of the first insertion hole (19). An upper end portion of the lower passage (16d) communicates with the second passage (16b).

[0083] A lower injection passage (65) extends from the second insertion hole (60). The lower injection passage (65) extends upward in the axial direction from the end of the second insertion hole (60). An upper end portion of the lower injection passage (65) communicates with the second injection passage (62).

[0084] As shown in FIGS. 5 and 6, the second body portion (56a) has a second discharge port (57). The second discharge port (57) penetrates the second body portion (56a) in the thickness direction. The second discharge port (57) allows the internal space (R) and the second discharge space (76) to communicate with each other.

[0085] Part of the second body portion (56a) that is around the second discharge port (57) is a second thin portion (58) that is thinner in the axial direction than the other part of the second body portion (56a). Part of the second thin portion (58) that is continuous with the second discharge port (57) is slightly thicker compared to the other part of the second thin portion (58).

[0086] The second discharge port (57) is provided with a second discharge valve (59). The second discharge valve (59) is disposed so as to cover the second discharge port (57). The second discharge valve (59) is released from the second discharge port (57) if the pressure of a refrigerant in the second discharge space (76) is more than or equal to a predetermined value. The refrigerant is discharged from the second discharge space (76) to the internal space (R) through the second discharge port (57) when the second discharge valve (59) is released from the second discharge port (57). The second discharge valve (59) covers the second discharge port (57) again after the refrigerant is discharged to the internal space (R).(3) Operation

[0087] Next, operation of the compressor (1) will be described with reference to FIG. 7. The operation of compressing a refrigerant by the first cylinder (31) and the first piston (35) and the operation of compressing a refrigerant by the second cylinder (41) and the second piston (45) are basically the same except that the phases are different by 180°. In the following, the operation of compressing a refrigerant by the first cylinder (31) and the first piston (35) will be described in detail, and the operation of compressing a refrigerant by the second cylinder (41) and the first piston (35) will not be described.

[0088] In the compressor (1), when the electric motor (20) is started to rotate the rotor (22), the rotary shaft (90) rotates and the first eccentric portion (91) rotates eccentrically. Then, as the first eccentric portion (91) rotates eccentrically, the first piston (35), which is restricted from rotating, turns along the inner peripheral surface of the first cylinder (31).

[0089] A suction phase of sucking a refrigerant into the first cylinder chamber (S1) will be described. When the rotary shaft (90) slightly rotates from the state in which the rotational angle is 0° (the state (A) in FIG. 7), the position at which the first piston (35) and the first cylinder (31) contact each other passes the inner peripheral end of the first suction port (17). At this time, suction of a refrigerant into the first suction space (71) starts.

[0090] The refrigerant is sucked from the suction pipe (14) via the suction passage (16) and the first suction port (17). Then, as the rotational angle of the rotary shaft (90) increases, the volume of the first suction space (71) gradually increases, and then the amount of the refrigerant sucked into the first suction space (71) increases (the states (B) to (H) in FIG. 7). This suction phase of sucking the refrigerant continues until the rotational angle of the rotary shaft (90) reaches 360°, and then it shifts to a discharge phase.

[0091] The discharge phase of compressing and discharging a refrigerant in the first cylinder chamber (S1) will be described. When the rotary shaft (90) slightly rotates from the state in which the rotational angle is 0° (the state (A) in FIG. 7), the position at which the first piston (35) and the first cylinder (31) contact each other passes the inner peripheral end of the first suction port (17) again. At this time, confinement of the refrigerant in the first suction space (71) is completed.

[0092] The first suction space (71) connected to the first suction port (17) turns into the first discharge space (72) connected to only the first discharge port (51). From this state, compression of the refrigerant in the first discharge space (72) starts. As the rotational angle of the rotary shaft (90) increases, the volume of the first discharge space (72) decreases and the pressure of the first discharge space (72) increases. When the pressure of the first discharge space (72) exceeds a predetermined pressure, the first discharge valve (53) opens.

[0093] When the first discharge valve (53) opens, the refrigerant in the first discharge space (72) is discharged from the first discharge port (51), flows into the internal space (R) of the closed container (10), and then is discharged to the outside of the compressor (1) through the discharge pipe (15). This discharge phase of discharging the refrigerant continues until the rotational angle of the rotary shaft (90) reaches 360°, and then it shifts to the suction phase.

[0094] In this manner, the suction phase and the discharge phase are repeated in the first cylinder chamber (S1). In the second cylinder chamber (S2), the suction phase and the discharge phase are repeated with the phase different by 180° from the phase of the first cylinder chamber (S1). Accordingly, the compressor (1) can continuously perform operation of compressing a refrigerant.(4) Seizing during Operation

[0095] In the discharge phase, when the rotational angle of the rotary shaft (90) is 360°, or in other words, when the piston (35, 45) is located at the top dead center, the volume of the discharge space (72, 76) is substantially zero. Meanwhile, a high-pressure refrigerant stays near the discharge port (51, 57) of the internal space (R). Since part of the front head (50) that is near the first discharge port (51) is the first thin portion (52), the first thin portion (52) is deformed so as to enter the first cylinder chamber (S1) as the pressure difference between the inside and outside of the first cylinder chamber (S1) increases. Also since part of the rear head (56) that is near the second discharge port (57) is the second thin portion (58), the second thin portion (58) is deformed so as to enter the second cylinder chamber (S2) as the pressure difference between the inside and outside of the second cylinder chamber (S2) increases.

[0096] Meanwhile, part of the piston (35, 45) that is near the discharge port (51, 57) is exposed to a compressed high-temperature refrigerant. In particular, in the first embodiment, the same portions of the pistons (35, 45) are exposed to a high-temperature refrigerant. Thus, when the piston (35, 45) is located at the top dead center, part of the piston (35, 45) that is near the discharge port (51, 57) is more likely to thermally expand compared to the suction-side part of the piston (35, 45), that is, part of the piston (35, 45) that is near the suction port (17, 18). Although the cylinder (31, 41) also thermally expands, the amount of deformation of the piston (35, 45) due to thermal expansion is larger because the piston (35, 45) has a lower heat capacity than the cylinder (31, 41). Thus, when the first piston (35) thermally expands, the first piston (35) is deformed so as to approach the front head (50) and the middle plate (55). Similarly, when the second piston (45) thermally expands, the second piston (45) is deformed so as to approach the rear head (56) and the middle plate (55).

[0097] If there occur both the deformation of the first thin portion (52) and the second thin portion (58) and the thermal expansion of the first piston (35) and the second piston (45), the gaps in the axial direction between the first thin portion (52) and the first piston (35) and between the second thin portion (58) and the second piston (45) may become zero. If the gaps become zero, seizing occurs between the first thin portion (52) and the first piston (35) and between the second thin portion (58) and the second piston (45).

[0098] The blade (38, 48) is also exposed to a high-temperature refrigerant, and thus is more likely to thermally expand compared to the suction-side part of the piston (35, 45). Thus, seizing may occur also between the first thin portion (52) and the first blade (38) and between the second thin portion (58) and the second blade (48).

[0099] In order to solve this problem, the piston (35, 45) and the blade (38, 48) of the first embodiment have devised surface shapes.(5) Surface Shape of Piston

[0100] The surface shapes of the piston (35, 45) and the blade (38, 48) will be described below. Since the first piston (35) and the second piston (45), as well as the first blade (38) and the second blade (48), are shaped inversely to each other in the top-bottom direction, the surface shapes of the first piston (35) and the first blade (38) will be mainly described below, and the surface shapes of the second piston (45) and the second blade (48) will not be described in detail below.

[0101] The first piston (35) has a first recessed portion (81) which is a surface recessed in the axial direction. FIG. 8 shows the area in which the first recessed portion (81) is provided. As shown in FIG. 8, when viewed in the axial direction, one of the intersections between the peripheral edge of the first discharge valve (53) and the inner edge of the first cylinder (31) that is closer to the bottom dead center of the first piston (35) is defined as a first point (P1), and the line segment that connects the first point (P1) with the center (X) of the rotary shaft (90) is defined as a first line segment (L1). When viewed in the axial direction, one of the intersections between the first suction port (17) and the inner edge of the first cylinder (31) that is closer to the bottom dead center of the first piston (35) is defined as a second point (P2), and the line segment that connects the second point (P2) with the center (X) of the rotary shaft (90) is defined as a second line segment (L2). When viewed in the axial direction, when the first piston (35) is located at the bottom dead center, the region which is closer to the first discharge space (72) between the side surface of the first blade (38) that is closer to the first discharge space (72) and the first line segment (L1), where the region is a region that overlaps the first cylinder bore (32), or particularly a region that overlaps the first cylinder chamber (S1), is defined as a first region (77). When viewed in the axial direction, when the first piston (35) is located at the bottom dead center, the region which is closer to the first suction space (71) between the side surface of the first blade (38) that is closer to the first suction space (71) and the second line segment (L2), where the region is a region that overlaps the first cylinder bore (32), or particularly a region that overlaps the first cylinder chamber (S1), is defined as a second region (78). The first recessed portion (81) is located in an area including the first region (77) when the first piston (35) is located at the bottom dead center. Specifically, when viewed in the axial direction, the first recessed portion (81) is located so as to include the area defined by 90° toward the first discharge port (51) about the center (DC1) of the first eccentric portion (91) with respect to the center line (CL) of the first blade (38) passing through the center (DC1) of the first eccentric portion (91). The first recessed portion (81) is located from the inner edge to the outer edge of the first piston (35) in the radial direction. The first recessed portion (81) is also formed so as to include the entire part of a coupling portion (38a) between the first piston (35) and the first blade (38). Accordingly, when the first piston (35) is located at the top dead center, the first recessed portion (81) is located in the area that overlaps the first discharge port (51).

[0102] As shown in FIGS. 9 and 10A, the first recessed portion (81) is a surface of the first piston (35) that is recessed in the axial direction compared to part of the first piston (35) that corresponds to the second region (78) (hereinafter simply referred to as "the part that corresponds to the second region (78)") when the first piston (35) is located at the bottom dead center. The first recessed portion (81) is formed on only one of the surfaces of the first piston (35) in the axial direction that is closer to the first discharge port (51). Specifically, in the first piston (35), the first recessed portion (81) is disposed on only the upper surface (35a) of the first piston (35) and is not disposed on the lower surface (35b) of the first piston (35).

[0103] In the first embodiment, the first recessed portion (81) is formed as a step portion. A bottom portion of the first recessed portion (81) is a flat surface extending in the radial direction. The thickness of the first blade (38) in the axial direction is smaller than the thickness of part of the first piston (35) that corresponds to the second region (78). The upper surface (38b) of the first blade (38) is flush with the bottom surface of the first recessed portion (81). The lower surface (38c) of the first blade (38) is flush with the lower surface of the first piston (35).

[0104] In FIGS. 9 and 10A, the depth of the first recessed portion (81) is illustrated in an enlarged scale for the sake of easy understanding of formation of the first recessed portion (81). Actually, the depth of the first recessed portion (81) is 2 µm to 20 µm, preferably 2 µm to 10 µm, and more preferably 2 µm to 5 µm.

[0105] The first recessed portion (81) is formed by processing the lower surface of the first piston (35). The processing method of forming the first recessed portion (81) is not particularly limited but may be laser processing or roller burnishing, for example.

[0106] As shown in FIG. 11, since the first recessed portion (81) is formed, there is a larger gap in the axial direction between the first piston (35) and the front head (50). Specifically, when the first piston (35) is located at the bottom dead center, a gap (CR1) in the axial direction between part of the outer edge of the first piston (35) that corresponds to the first region (77) and part of the front head (50) that corresponds to the first region (77) is larger than a gap (CR2) in the axial direction between part of the first piston (35) that corresponds to the second region (78) and part of the front head (50) that corresponds to the second region (78). The same applies to the position of the inner edge of the first piston (35). The "part of the front head (50) that corresponds to the first region (77)" means not only the entire part of the front head (50) that is included in the first region (77) but also only a partial part of the front head (50) that is included in the first region (77).

[0107] As shown in FIG. 10B, in the second piston (45), the first recessed portion (81) is disposed on only the lower surface (45b) of the second piston (45) and is not disposed on the upper surface (45a) of the second piston (45). The upper surface (48b) of the second blade (48) is flush with the upper surface (45a) of the second piston (45), and the lower surface (48c) of the second blade (48) is flush with the bottom surface of the first recessed portion (81). The area of the second piston (45) in which the first recessed portion (81) is located is the same as the area of the first piston (35) in which the first recessed portion (81) is located.

[0108] Although not shown in detail, when the second piston (45) is located at the bottom dead center, a gap (CR1) in the axial direction between part of the outer edge of the second piston (45) that corresponds to the first region (77) and part of the rear head (56) that corresponds to the first region (77) is larger than a gap (CR2) in the axial direction between part of the second piston (45) that corresponds to the second region (78) and part of the rear head (56) that corresponds to the second region (78). The same applies to the position of the inner edge of the second piston (45). The "part of the rear head (56) that corresponds to the first region (77)" means not only the entire part of the rear head (56) that is included in the first region (77) but also only a partial part of the rear head (56) that is included in the first region (77).(6) Advantages of First Embodiment

[0109] In the rotary compressor (1) of the first embodiment, when the first piston (35) is located at the bottom dead center, the gap (CR1) in the axial direction between part of the outer edge of the first piston (35) that corresponds to the first region (77) and part of the front head (50) that corresponds to the first region (77) is larger than the gap (CR2) in the axial direction between part of the first piston (35) that corresponds to the second region (78) and part of the front head (50) that corresponds to the second region (78). Accordingly, even if there occur both the deformation of the thin portion (52, 58) and the thermal expansion of the piston (35, 45) where the pressure outside the cylinder chamber (S1, S2) is higher than the pressure inside the cylinder chamber (S1, S2), it is possible to prevent the gap in the axial direction between the first piston (35) and the front head (50) and the gap in the axial direction between the second piston (45) and the rear head (56) from becoming zero. Thus, the rotary compressor (1) of the first embodiment can reduce seizing between the piston (35) and the front head (50) and between the piston (45) and the rear head (56).

[0110] In particular, the outer edge of the piston (35, 45) comes into direct contact with a compressed refrigerant, and thus the amount of expansion due to thermal expansion tends to be large. Since the gap (CR1) is larger at the outer edge of the piston (35, 45), the rotary compressor (1) of the first embodiment can effectively reduce seizing between the piston (35) and the front head (50) and between the piston (45) and the rear head (56).

[0111] In the rotary compressor (1) of the first embodiment, part of the piston (35, 45) that corresponds to the first region (77) has the first recessed portion (81) which is a surface recessed in the axial direction compared to part of the piston (35, 45) that corresponds to the second region (78). The first recessed portion (81) can widen the gap (CR1) in the axial direction between the piston (35, 45) and the thin portion (52, 58). It is possible to easily form the first recessed portion (81) on the piston (35, 45) by laser processing, roller burnishing, or the like, after forming the piston (35, 45). With simple processing, the rotary compressor (1) of the first embodiment can reduce seizing between the piston (35) and the front head (50) and between the piston (45) and the rear head (56).

[0112] In the rotary compressor (1) of the first embodiment, the first recessed portion (81) is formed as a step portion. Thus, it is possible to easily form the first recessed portion (81) on the piston (35, 45). With simple processing, the rotary compressor (1) of the first embodiment can reduce seizing between the piston (35) and the front head (50) and between the piston (45) and the rear head (56).

[0113] In the rotary compressor (1) of the first embodiment, when viewed in the axial direction, the first recessed portion (81) is located so as to include the area defined by 90° toward the discharge port (51, 57) about the center (DC1, DC2) of the eccentric portion (91, 92) with respect to the center line (CL) of the blade (38, 48) passing through the center (DC1, DC2) of the eccentric portion (91, 92). The first recessed portion (81) is limited to the area included in part of the piston (35, 45) that is near the discharge port (51, 57). Accordingly, it is possible to narrow the area in which the gaps in the axial direction between the piston (35) and the front head (50) and between the piston (45) and the rear head (56) can be widened. While enhancing the efficiency of compression, the rotary compressor (1) of the first embodiment can reduce seizing between the piston (35) and the front head (50) and between the piston (45) and the rear head (56).

[0114] In the rotary compressor (1) of the first embodiment, the first recessed portion (81) is located on only the surface (35a, 45b) among the surfaces (35a, 35b, 45a, 45b) of the piston (35, 45) in the axial direction that is closer to the discharge port (51, 57). Accordingly, it is possible to narrow the area in which the gaps in the axial direction between the piston (35) and the front head (50) and between the piston (45) and the rear head (56) can be widened. While enhancing the efficiency of compression, the rotary compressor (1) of the first embodiment can reduce seizing between the piston (35) and the front head (50) and between the piston (45) and the rear head (56).

[0115] In the rotary compressor (1) of the first embodiment, the gap in the axial direction between the surface (38b) of the first blade (38) that is closer to the first discharge port (51) and the front head (50) is larger than the gap (CR2) in the axial direction between part of the first piston (35) that corresponds to the second region (78) and part of the front head (50) that corresponds to the second region (78). In addition, the gap in the axial direction between the surface (48c) of the second blade (48) that is closer to the second discharge port (57) and the rear head (56) is larger than the gap (CR2) in the axial direction between part of the second piston (45) that corresponds to the second region (78) and part of the rear head (56) that corresponds to the second region (78). Accordingly, it is possible to reduce seizing between the blade (38) and the front head (50) and between the blade (48) and the rear head (56) even if the blade (38, 48) thermally expands due to a high-temperature and high-pressure refrigerant.

[0116] In the rotary compressor (1) of the first embodiment, the surface (38b) of the first blade (38) that is closer to the first discharge port (51) is flush with the bottom surface of the first recessed portion (81) of the first piston (35). In addition, the surface (48c) of the second blade (48) that is closer to the second discharge port (57) is flush with the bottom surface of the first recessed portion (81) of the second piston (45). Processing of the blade (38, 48) can be conducted simultaneously with a process of forming the first recessed portion (81) on the piston (35, 45). With simple processing, the rotary compressor (1) of the first embodiment can reduce seizing between the first piston (35) and the front head (50) and seizing between the second piston (45) and the rear head (56).

[0117] In the rotary compressor (1) of the first embodiment, the refrigerant is carbon dioxide. Carbon dioxide is more likely to create a high pressure near the discharge port (51, 57) outside the cylinder chamber (S1, S2) compared to other refrigerants. Thus, when carbon dioxide is employed, the thin portion (52, 58) is likely to be deformed toward the cylinder chamber (S1, S2). The rotary compressor (1) of the first embodiment can reduce seizing between the piston (35) and the front head (50) and between the piston (45) and the rear head (56) even if carbon dioxide is used.(7) Variations

[0118] The first embodiment may be modified as the following variations. In the following description, the differences from the first embodiment will be described in principle.(7-1) First Variation

[0119] A rotary compressor (1) of a first variation has a piston (35, 45) and a blade (38, 48) configured differently from those of the first embodiment.

[0120] In addition to the first recessed portion (81), the piston (35, 45) of the first variation has a second recessed portion (82) provided on a surface (35b, 45a) among the surfaces of the piston (35, 45) in the axial direction that is farther from the discharge port (51, 57). FIG. 12 shows the first piston (35) and the first blade (38) of the first variation. The second recessed portion (82) of the first piston (35) is located on the lower surface (35b) of the first piston (35). Although not shown, the second recessed portion (82) of the second piston (45) is located on the upper surface (45a) of the second piston (45).

[0121] The second recessed portion (82) is located at a position that overlaps the first recessed portion (81) when viewed in the axial direction. Specifically, the second recessed portion (82) is located so as to include the area defined by 90° toward the second discharge port (57) about the center (DC2) of the second eccentric portion (92) with respect to the center line of the second blade (48) passing through the center (DC2) of the second eccentric portion (92). The area of the second recessed portion (82) is not necessarily the same as the area of the first recessed portion (81). The second recessed portion (82) may be located in a different area from the first recessed portion (81) as long as overlapping the first recessed portion (81) when viewed in the axial direction.

[0122] The second recessed portion (82) is recessed in the axially opposite direction to the first recessed portion (81). The depth of the second recessed portion (82) is the same as the depth of the first recessed portion (81). The depth of the second recessed portion (82) is not necessarily the same as the depth of the first recessed portion (81), and may be shallower or may be deeper than the first recessed portion (81).

[0123] The blade (38, 48) has a smaller thickness in the axial direction compared to the first embodiment. As shown in FIG. 12, the upper surface (38b) of the first blade (38) is flush with the bottom surface of the first recessed portion (81), and the lower surface (38c) of the first blade (38) is flush with the lower surface of the bottom portion of the second recessed portion (82).

[0124] Although not shown, the second piston (45) and the second blade (48) are configured inversely in the top-bottom direction to the first piston (35) and the first blade (38). Specifically, the second recessed portion (82) of the second piston (45) is located on the upper surface (45a) of the second piston (45). The upper surface (48b) of the second blade (48) is flush with the bottom surface of the second recessed portion (82), and the lower surface (48c) of the second blade (48) is flush with the lower surface of the bottom portion of the first recessed portion (81).

[0125] If the piston (35, 45) thermally expands significantly, there occurs seizing between the discharge-side part of the piston (35, 45) and the middle plate (55). In the rotary compressor (1) of the first variation, the piston (35, 45) has the second recessed portion (82), and thus it is possible to reduce seizing between the discharge-side part of the piston (35, 45) and the middle plate (55).

[0126] When like this first variation the second recessed portion (82) is formed at the same position and in the same shape as the first recessed portion (81), the piston (35, 45) has a symmetrical shape in the axial direction. Thus, it is unnecessary to consider the orientation in the top-bottom direction to install the piston (35, 45) in the cylinder (31, 41). The rotary compressor (1) of the first variation can be manufactured easily.(7-2) Second Variation

[0127] A rotary compressor (1) of a second variation has a piston (35, 45) and a blade (38, 48) configured differently from those of the first embodiment.

[0128] FIGS. 13 and 14 show the first piston (35) and the first blade (38) of the second variation. In the first piston (35) of the second variation, the bottom surface of the first recessed portion (81) is an inclined surface. When the first piston (35) is located at the top dead center, part of the first recessed portion (81) that is closer to the first discharge port (51) in the circumferential direction is deeper relative to part of the first piston (35) that corresponds to the second region (78). The first recessed portion (81) is deeper at the outer edge than at the inner edge of the first piston (35). When the first piston (35) is located at the top dead center, the part that overlaps the first discharge port (51) when viewed in the axial direction is a valley portion (81a). The depth of the first recessed portion (81) is 2 µm to 20 µm, preferably 2 µm to 10 µm, and more preferably 2 µm to 5 µm at the deepest position of the valley portion (81a).

[0129] As shown in FIG. 13, the upper surface (38b) of the first blade (38) is an inclined surface. Part of the upper surface (38b) of the first blade (38) that is closer in the radial direction to the coupling portion (38a) between the first piston (35) and the first blade (38) is deeper relative to the suction-side part of the first piston (35). At the coupling portion (38a), there is no step between the first blade (38) and the first piston (35).

[0130] Although not shown, the first recessed portion (81) of the second piston (45) and the second blade (48) have inclined surfaces similarly to the first recessed portion (81) of the first piston (35) and the first blade (38). The first recessed portion (81) of the second piston (45) and the second blade (48) are configured inversely in the top-bottom direction to the first recessed portion (81) of the first piston (35) and the first blade (38).

[0131] When the thin portion (52, 58) is deformed toward the cylinder chamber (S1, S2) with the coupling portion between the thin portion (52, 58) and the other part as the point of support, part of the thin portion (52, 58) that is closer to the discharge port (51, 57) yields a larger amount of displacement. Thus, seizing is likely to occur particularly at part of the thin portion (52, 58) that is around the discharge port (51, 57). In the rotary compressor (1) of the second variation, part of the first recessed portion (81) that is closer to the discharge port (51, 57) in the circumferential direction is deeper relative to part of the piston (35, 45) that corresponds to the second region (78). The rotary compressor (1) of the second variation can reduce seizing between the piston (35) and the front head (50) and between the piston (45) and the rear head (56) even when part of the thin portion (52, 58) that is around the discharge port (51, 57) is displaced significantly.

[0132] Part of the piston (35, 45) that is on the outer side in the radial direction is closer to the discharge space (72, 76), and thus the amount of deformation due to thermal expansion tends to be large. In the rotary compressor (1) of the second variation, the first recessed portion (81) is deeper at the outer edge than at the inner edge of the first piston (35). The rotary compressor (1) of the second variation can reduce seizing between the piston (35) and the front head (50) and between the piston (45) and the rear head (56) even when the amount of deformation of the piston (35, 45) due to thermal expansion is large.

[0133] Part of the blade (38, 48) that is closer to the coupling portion (38a, 48a) coupling with the piston (35, 45) is closer to the discharge port (51, 57). In the rotary compressor (1) of the second variation, the surface of the blade (38, 48) that is closer to the discharge port (51, 57) is the surface (38b, 48c), where part of the surface (38b, 48c) that is closer in the radial direction to the coupling portion (38a, 48a) between the piston (35, 45) and the blade (38, 48) is deeper relative to part of the piston (35, 45) that corresponds to the second region (78). The rotary compressor (1) of the second variation can reduce seizing between the blade (38) and the front head (50) and between the blade (48) and the rear head (56) even when part of the thin portion (52, 58) that is around the discharge port (51, 57) is displaced significantly.(7-3) Third Variation

[0134] A rotary compressor (1) of a third variation has a piston (35, 45) and a blade (38, 48) configured differently from those of the first embodiment.

[0135] FIG. 15 shows the first piston (35) and the first blade (38) of the third variation. In the first piston (35) of the third variation, the area of the first recessed portion (81) in the circumferential direction is smaller compared to the first embodiment. Specifically, the first recessed portion (81) is disposed on only half of the coupling portion (38a) between the first piston (35) and the first blade (38) on which the first discharge port (51) is disposed (the left side in FIG. 15). In other words, the first recessed portion (81) is not disposed on half of the coupling portion (38a) that is on the suction side. In addition, in the first blade (38), only half of the upper surface (38b) that extends from the center line (CL) toward the first discharge port (51) is recessed relative to part of the first piston (35) that corresponds to the second region (78). In the first blade (38), half of the upper surface (38b) that extends from the center line (CL) toward the first suction port (17) is flush with part of the first piston (35) that corresponds to the second region (78).

[0136] Although not shown, the first recessed portion (81) of the second piston (45) and the second blade (48) are configured inversely in the top-bottom direction to the first recessed portion (81) of the first piston (35) and the first blade (38).

[0137] In the rotary compressor (1) of the third variation, it is possible to narrow the area in which the gaps in the axial direction between the piston (35) and the front head (50); between the piston (45) and the rear head (56); between the blade (38) and the front head (50); and between the blade (48) and the rear head (56) can be widened. While enhancing the efficiency of compression, the rotary compressor (1) of the third variation can reduce seizing between the piston (35) and the front head (50) and between the piston (45) and the rear head (56).(7-4) Fourth Variation

[0138] A rotary compressor (1) of a fourth variation has a piston (35, 45) configured differently from that of the first embodiment.

[0139] FIG. 16 shows the first piston (35) and the first blade (38) of the fourth variation. The first piston (35) of the fourth variation has a third recessed portion (83) which is located in part of the first piston (35) that is different in the circumferential direction from part on which the first recessed portion (81) is located and which is a surface recessed in the axial direction. In the example of FIG. 16, the third recessed portion (83) is located on the upper surface (35a) of the first piston (35). The third recessed portion (83) is located on part of the first piston (35) that is different from the first region (77) and the second region (78). The third recessed portion (83) is located on part of the first piston (35) that is different in the circumferential direction by 180° from part on which the first recessed portion (81) is located. The area of the third recessed portion (83) in the circumferential direction is smaller than the area of the first recessed portion (81) in the circumferential direction. The depth of the third recessed portion (83) is the same as the depth of the first recessed portion (81). The third recessed portion (83) may be disposed on the lower surface (35b) of the first piston (35). The depth of the third recessed portion (83) is not necessarily the same as the depth of the first recessed portion (81), and may be shallower or may be deeper than the first recessed portion (81).

[0140] Although not shown, the third recessed portion (83) of the second piston (45) are configured inversely in the top-bottom direction to the third recessed portion (83) of the first piston (35).

[0141] Due to not only the pressure difference between the inside and outside of the cylinder chamber (S1, S2) or the thermal expansion of the piston (35, 45) but the axial force or thermal deformation of the through bolt (B), the gaps in the axial direction between the piston (35) and the front head (50), between the piston (35, 45) and the middle plate (55), and between the piston (45) and the rear head (56) may become narrower. Since the third recessed portion (83) is disposed, the rotary compressor (1) of the fourth variation can reduce seizing also at the part other than near the discharge port (51, 57) between the piston (35) and the front head (50), between the piston (35, 45) and the middle plate (55), and between the piston (45) and the rear head (56).(7-5) Fifth Variation

[0142] A rotary compressor (1) of a fifth variation has a piston (35, 45) configured differently from that of the first embodiment.

[0143] FIG. 17 shows the first piston (35) and the first blade (38) of the fifth variation. The first piston (35) of the fifth variation has an inclined surface (84) between the first recessed portion (81) and the upper surface (35a). The inclined surface (84) is formed at both end portions of the first recessed portion (81) in the circumferential direction of the first piston (35).

[0144] As shown in FIG. 18, the inclined surface (84) is an inclined curved surface, part of which is near the upper surface (35a) is raised upward, and part of which is near the first recessed portion (81) is raised downward. The inclined surface (84) and the upper surface (35a) are smoothly continuous with each other. The inclined surface (84) and the first recessed portion (81) are smoothly continuous with each other. The "smoothly continuous" means continuous without steps or tangentially continuous.

[0145] Although not shown, the inclined surface (84) of the second piston (45) is configured inversely in the top-bottom direction to the inclined surface (84) of the first piston (35).

[0146] Due to not only the pressure difference between the inside and outside of the cylinder chamber (S1, S2) or the thermal expansion of the piston (35, 45) but the axial force or thermal deformation of the through bolt (B), the gaps in the axial direction between the piston (35) and the front head (50), between the piston (35, 45) and the middle plate (55), and between the piston (45) and the rear head (56) may become narrower. Since the inclined surface (84) is disposed at both ends of the first recessed portion (81), it is possible to prevent a boundary portion between the first recessed portion (81) and the upper surface (35a) from catching on the front head (50), the middle plate (55), and the rear head (56) when the piston (35, 45) rotates. Thus, the rotary compressor (1) of the fifth variation can reduce seizing also at the part other than near the discharge port (51, 57) between the piston (35) and the front head (50), between the piston (35, 45) and the middle plate (55), and between the piston (45) and the rear head (56).

[0147] The inclined surface (84) may be formed as not an inclined curved surface but one or more inclined flat surfaces. If the inclined surface (84) is an inclined flat surface, the inclined surface (84) is not necessarily smoothly continuous with the upper surface (35a) and the first recessed portion (81). Even if the inclined surface (84) is an inclined curved surface, the inclined surface (84) is not necessarily smoothly continuous with the upper surface (35a) and the first recessed portion (81), and the boundary between the inclined surface (84) and the upper surface (35a) and the boundary between the inclined surface (84) and the first recessed portion (81) may be slightly angled.<Second Embodiment>

[0148] A second embodiment of the present disclosure will be described in detail with reference to the drawings. In the following description, the same elements as those of the first embodiment are denoted by the same reference numerals, and the detailed description thereof will be omitted.(8) Front Head and Rear Head

[0149] A rotary compressor (201) of a second embodiment has a front head (250) and a rear head (256) configured differently from those of the first embodiment. Specifically, in the second embodiment, the front head (250) and the rear head (256) have fourth recessed portions (252a, 258a) which are recessed surfaces close to the cylinder chamber (S1, S2). In the second embodiment, the piston (235, 245) does not have the first recessed portion.

[0150] As shown in FIG. 19, the surface of the front head (250) that is closer to the first cylinder chamber (S1) has the fourth recessed portion (252a) located on the part that corresponds to a first region (277) and recessed compared to the part that corresponds to a second region (278). The fourth recessed portion (252a) of the front head (250) is located only in a part of the first region (277) that is around a first discharge port (251).

[0151] Since the fourth recessed portion (252a) is formed on the front head (250), there is a larger gap in the first region (277) and in the axial direction between the first piston (235) and the front head (250). Specifically, when the first piston (235) is located at the bottom dead center, a gap (CR3) in the axial direction between part of the first piston (235) that corresponds to the first region (277) and part of the front head (250) that corresponds to the first region (277) is larger than a gap (CR4) in the axial direction between part of the first piston (235) that corresponds to the second region (278) and part of the front head (250) that corresponds to the second region (278).

[0152] As shown in FIG. 20, the surface of the rear head (256) that is closer to the second cylinder chamber (S2) has the fourth recessed portion (258a) located on the part that corresponds to the first region (277) and recessed compared to the part that corresponds to the second region (278). The fourth recessed portion (258a) of the rear head (256) is located in part of the first region (277) that is around a second discharge port (257).

[0153] Since the fourth recessed portion (258a) is formed on the rear head (256), there is a larger gap in the first region (277) and in the axial direction between the second piston (245) and the rear head (256). Specifically, when the second piston (245) is located at the bottom dead center, a gap (CR5) in the axial direction between part of the second piston (245) that corresponds to the first region (277) and part of the rear head (256) that corresponds to the first region (277) is larger than a gap (CR6) in the axial direction between part of the second piston (245) that corresponds to the second region (278) and part of the rear head (256) that corresponds to the second region (278).

[0154] The depth of the fourth recessed portion (252a, 258a) is 2 µm to 20 µm, preferably 2 µm to 10 µm, and more preferably 2 µm to 5 µm. Part of a thin portion (252, 258) is slightly thinned due to the fourth recessed portion (252a, 258a). However, the area of the fourth recessed portion (252a, 258a) in the thin portion (252, 258) is only in a part of the thin portion (252, 258) that corresponds to the first region (277). The depth of the fourth recessed portion (252a, 258a) is about 20 µm maximum. Thus, the fourth recessed portion (252a, 258a) has little influence that can help deform the thin portion (252, 258).(9) Advantages of Second Embodiment

[0155] In the second embodiment, part of the front head (250) that corresponds to the first region (277) has the fourth recessed portion (252a) which is a surface close the first cylinder chamber (S1) and recessed compared to part of the front head (250) that corresponds to the second region (278). Part of the rear head (256) that corresponds to the first region (277) has the fourth recessed portion (258a) which is a surface closer to the second cylinder chamber (S2) and recessed compared to part of the rear head (256) that corresponds to the second region (278). Accordingly, in the part that corresponds to the first region (277), it is possible to widen the gap in the axial direction between the front head (250) and the first piston (235) and the gap in the axial direction between the rear head (256) and the second piston (245). Even if there occur both the deformation of the thin portion (252, 258) and the thermal expansion of the piston (235, 245) where the pressure outside the cylinder chamber (S1, S2) is higher than the pressure inside the cylinder chamber (S1, S2), it is possible to prevent the gap in the axial direction between the first piston (235) and the front head (250) and the gap in the axial direction between the second piston (245) and the rear head (256) from becoming zero. Thus, the rotary compressor (1) of the second embodiment can reduce seizing between the piston (235) and the front head (250) and between the piston (245) and the rear head (256).

[0156] In the second embodiment, the fourth recessed portion (252a, 258a) of the front head (250) and the rear head (256) is located only in a part of the first region (277) that is around the discharge port (251, 257). Accordingly, in the rotary compressor (201), it is possible to narrow the area in which the gaps between the piston (235) and the front head (250) and between the piston (245) and the rear head (256) can be widened. While enhancing the efficiency of compression, the rotary compressor (201) of the second embodiment can reduce seizing between the piston (235) and the front head (250) and between the piston (245) and the rear head (256).<Other Embodiments>

[0157] As shown in FIG. 21, a compression mechanism (330) of a rotary compressor (301) may have two suction pipes, namely, a first suction pipe (314a) and a second suction pipe (314b). In FIG. 21, the first suction pipe (314a) is connected to a first suction port (317) of a first cylinder (331). The second suction pipe (314b) is connected to a second suction port (318) of a second cylinder (341). In the example shown in FIG. 21, the suction passage provided in the first embodiment is not provided, and the suction port (317, 318) is directly connected to the suction pipe (314a, 314b). The first suction pipe (314a) may be disposed in a front head (350), and the second suction pipe (314b) may be disposed in a rear head (356). One or both of the first suction pipe (314a) and the second suction pipe (314b) may be disposed in a middle plate (355). In these cases, it is necessary to provide the suction passage.

[0158] As shown in FIG. 22, a compression mechanism (430) of a rotary compressor (401) may be a single-cylinder-type compression mechanism with one piston (35) and one eccentric portion (91). In the example shown in FIG. 22, a suction pipe (414) is inserted into an insertion hole (419) of a rear head (456). The suction pipe (414) is connected to a suction port (417) via a suction passage (416) formed in the rear head (456) and a cylinder (431). The suction pipe (414) may be disposed in any of a front head (450) and the cylinder (431).

[0159] All of the first recessed portion (81), the second recessed portion (82), and the third recessed portion (83) may be disposed in the piston (35).

[0160] The first recessed portion (81) may be disposed in the piston (35), and the fourth recessed portion (252a, 258a) may be disposed in the front head (50, 250) and the rear head (56, 256, 456).

[0161] The gap in the axial direction between the surface (38b) of the first blade (38) that is closer to the first discharge port (51) and the front head (50) may be equal to the gap (CR2) in the axial direction between part of the first piston (35) that corresponds to the second region (78, 278) and part of the front head (50) that corresponds to the second region (78, 278). The gap in the axial direction between the surface (48c) of the second blade (48) that is closer to the second discharge port (57) and the rear head (56) may be equal to the gap (CR2) in the axial direction between part of the second piston (45) that corresponds to the second region (78, 278) and part of the rear head (56) that corresponds to the second region (78, 278).

[0162] The compressor (1) may be a hinge-vane-type compressor in which a blade separate from the piston (35, 45) is rotatably fixed to an end portion of the piston (35, 45).

[0163] While the embodiments and the variations thereof have been described above, it will be understood that various changes in form and details may be made without departing from the spirit and scope of the claims. The embodiments, the variations thereof, and the other embodiments may be combined and replaced with each other without deteriorating intended functions of the present disclosure.

[0164] The expressions of "first", "second", and "third" described above are used to distinguish the terms to which these expressions are given, and do not limit the number and order of the terms.INDUSTRIAL APPLICABILITY

[0165] As described above, the present disclosure is useful for a rotary compressor.DESCRIPTION OF REFERENCE CHARACTERS

[0166] 1Rotary Compressor 31First Cylinder 35First Piston 35aUpper Surface (Surface Closer to Discharge Port) 35bLower Surface (Surface Farther From Discharge Port) 38First Blade 38aCoupling Portion 38bUpper Surface 41Second Cylinder 45Second Piston 45aUpper Surface (Surface Farther From Discharge Port) 45bLower Surface (Surface Closer to Discharge Port) 48Second Blade 48aCoupling Portion 48cLower Surface 50Front Head (Closing Member) 51First Discharge Port 52First Thin Portion 55Middle Plate (Closing Member) 56Rear Head (Closing Member) 57Second Discharge Port 58Second Thin Portion 77First Region 78Second Region 81First Recessed Portion 82Second Recessed Portion 83Third Recessed Portion 90Rotary Shaft 91First Eccentric Portion 92Second Eccentric Portion 100Refrigeration Apparatus 201Rotary Compressor 235First Piston 245Second Piston 250Front Head (Closing Member) 251First Discharge Port 252First Thin Portion 256Rear Head (Closing Member) 257Second Discharge Port 258Second Thin Portion 252aFourth Recessed Portion 258aFourth Recessed Portion 277First Region 278Second Region 301Rotary Compressor 331First Cylinder 341Second Cylinder 350Front Head (Closing Member) 355Middle Plate (Closing Member) 356Rear Head (Closing Member) 401Rotary Compressor 431Cylinder 450Front Head (Closing Member) 456Rear Head (Closing Member) DC1Center of First Eccentric Portion DC2Center of Second Eccentric Portion L1First Line Segment L2Second Line Segment LCCenter Line P1First Point P2Second Point XCenter of Rotary Shaft

Claims

1. A rotary compressor comprising: a cylinder (31, 41, 331, 341, 431) in which a cylinder chamber (S1, S2) is provided; a piston (35, 45, 235, 245) configured not to rotate but to turn along an inner surface of the cylinder chamber (S1, S2); a rotary shaft (90) configured to turn the piston (35, 45, 235, 245); a blade (38, 48) coupled with the piston (35, 45, 235, 245) and dividing the cylinder chamber (S1, S2) into a suction space (71, 75) and a discharge space (72, 76); a suction port (17, 18, 317, 318, 417) configured to supply a refrigerant to the suction space (71, 75); and a closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) configured to close both end portions of the cylinder chamber (S1, S2) in an axial direction of the rotary shaft (90), wherein at a position of the piston (35, 45, 235, 245), the rotary shaft (90) includes an eccentric portion (91, 92) that is eccentric with respect to a center (X) of the rotary shaft (90), the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) includes a discharge port (51, 57, 251, 257) communicating with the discharge space (72, 76) and discharging a compressed refrigerant from the discharge space (72, 76), and a thin portion (52, 58, 252, 258) formed in an area including a surrounding area of the discharge port (51, 57, 251, 257) and having a smaller thickness in the axial direction than another part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456), when viewed in the axial direction, a line segment that connects a first point (P1), one of the intersections between an outer edge of the thin portion (52, 58, 252, 258) and an inner edge of the cylinder (31, 41) that is closer to a bottom dead center of the piston (35, 45, 235, 245), with the center (X) of the rotary shaft (90) is defined as a first line segment (L1), and a line segment that connects a second point (P2), one of the intersections between the suction port (17, 18, 317, 318, 417) and the inner edge of the cylinder (31, 41) that is closer to the bottom dead center of the piston (35, 45, 235, 245), with the center (X) of the rotary shaft (90) is defined as a second line segment (L2), a region that overlaps the cylinder chamber (S1, S2) between the blade (38, 48) and the first line segment (L1) when the piston (35, 45, 235, 245) is located at the bottom dead center is defined as a first region (77, 277), a region that overlaps the cylinder chamber (S1, S2) between the blade (38, 48) and the second line segment (L2) when the piston (35, 45, 235, 245) is located at the bottom dead center is defined as a second region (78, 278), and when the piston (35, 45, 235, 245) is located at the bottom dead center, a gap (CR1) between part of an outer edge of the piston (35, 45, 235, 245) that corresponds to the first region (77, 277) and part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that corresponds to the first region (77, 277) is larger than a gap (CR2) between part of the piston (35, 45, 235, 245) that corresponds to the second region (78, 278) and part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that corresponds to the second region (78, 278).

2. The rotary compressor of claim 1, wherein part of the piston (35, 45, 235, 245) that corresponds to the first region (77, 277) has a first recessed portion (81) which is a surface recessed in the axial direction compared to the part of the piston (35, 45, 235, 245) that corresponds to the second region (78, 278).

3. The rotary compressor of claim 2, wherein when viewed in the axial direction, the first recessed portion (81) is located so as to include an area defined by 90° toward the discharge port (51, 57, 251, 257) about a center (DC1, DC2) of the eccentric portion (91, 92) with respect to a center line (CL) of the blade (38, 48) passing through the center (DC1, DC2) of the eccentric portion (91, 92).

4. The rotary compressor of claim 2 or 3, wherein the first recessed portion (81) is located on only a surface (35a, 45b) among surfaces (35a, 35b, 45a, 45b) of the piston (35, 45, 235, 245) in the axial direction that is closer to the discharge port (51, 57, 251, 257).

5. The rotary compressor of claim 2 or 3, wherein the first recessed portion (81) is located on a surface (35a, 45b) among surfaces (35a, 35b, 45a, 45b) of the piston (35, 45, 235, 245) in the axial direction that is closer to the discharge port (51, 57, 251, 257), and a surface (35b, 45a) among the surfaces (35a, 35b, 45a, 45b) of the piston (35, 45, 235, 245) in the axial direction that is farther from the discharge port (51, 57, 251, 257) has a second recessed portion (82) which is located at a position that overlaps the first recessed portion (81) when viewed in the axial direction and which is recessed in an opposite direction to the first recessed portion (81).

6. The rotary compressor of any one of claims 2 to 5, wherein when the piston (35, 45, 235, 245) is located at a top dead center, part of the first recessed portion (81) that is closer to the discharge port (51, 57, 251, 257) in a circumferential direction of the piston (35, 45, 235, 245) is deeper relative to part of the piston (35, 45, 235, 245) that is on a suction side.

7. The rotary compressor of any one of claims 2 to 6, wherein the piston (35, 45, 235, 245) has a third recessed portion (83) which is located in part of the piston (35, 45, 235, 245) that is different in the circumferential direction from part on which the first recessed portion (81) is located and which is a surface recessed in the axial direction.

8. The rotary compressor of any one of claims 1 to 7, wherein a gap between at least part of the blade (38, 48) and the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) is larger than a gap (CR2) between the part of the piston (35, 45, 235, 245) that is on the suction side and part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that is on the suction side.

9. The rotary compressor of claim 8, wherein the at least part of the blade (38, 48) is part which is located close to the discharge port (51, 57, 251, 257) and which is part of a surface (38b, 48c) that is recessed in the axial direction compared to part of the blade (38, 48) that is closer to the suction port (17, 18, 317, 318, 417).

10. The rotary compressor of claim 8 or 9, wherein the at least part of the blade (38, 48) that is closer to a coupling portion between the piston (35, 45, 235, 245) and the blade (38, 48) is deeper relative to part of the piston (35, 45, 235, 245) that is on a suction side.

11. The rotary compressor of any one of claims 1 to 10, wherein the part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that corresponds to the first region (77, 277) has a fourth recessed portion (252a, 258a) which is a surface closer to the cylinder chamber (S1, S2) and recessed compared to the part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that corresponds to the second region (78, 278), and the fourth recessed portion (252a, 258a) is located only in a part of the closing member (50, 56, 250, 256, 350, 355, 356, 450, 456) that is around the discharge port (51, 57, 251, 257).

12. The rotary compressor of any one of claims 1 to 11, wherein the refrigerant is carbon dioxide.

13. A refrigeration apparatus comprising: the rotary compressor (1, 201, 301, 401) of any one of claims 1 to 12.

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