Rotary compressor and refrigeration device

Abstract

In a rotary compressor (10), a first cylinder chamber (37) defined by a front head (31) and a middle plate (38) is formed inside a first cylinder (35), and a second cylinder chamber (42) defined by a middle plate and a rear head (43) is formed inside a second cylinder (40). A first piston (50) and a second piston (60) are accommodated in the first cylinder chamber and the second cylinder chamber, respectively. The diameters Ds of both the first cylinder chamber and the second cylinder chamber and the thickness Tm of the middle plate satisfy the relational expression represented by 1 / 30 ≤ Tm / Ds ≤ 1 / 10.

Description

Rotary compressor and refrigeration device

[0001] The present disclosure relates to a rotary compressor and a refrigeration device.

[0002] A known type of rotary compressor is a twin-cylinder rotary compressor. A twin-cylinder rotary compressor houses an inner rotor motor, a drive shaft connected to the motor, and a compression mechanism driven by rotation of the drive shaft within a cylindrical sealed container, with the axial direction of the drive shaft aligned vertically. The compression mechanism is a twin-cylinder type and includes a first head, a first cylinder, a middle plate, a second cylinder, and a second head.

[0003] The first cylinder defines a first cylinder chamber, and the second cylinder defines a second cylinder chamber. The first head is provided on the upper surface of the first cylinder and defines the first cylinder chamber. The middle plate is interposed between the first and second cylinders and separates the first and second cylinder chambers. The second head is provided on the lower surface of the second cylinder and defines the second cylinder chamber.

[0004] A first roller is housed in the first cylinder chamber, and a second roller is housed in the second cylinder chamber. The crankshaft has a first eccentric portion that fits onto the first roller and a second eccentric portion that fits onto the second roller, and is supported by the first head and the second head. In the compression mechanism, as the crankshaft rotates, the first roller rotates eccentrically in the first cylinder chamber and the second roller rotates eccentrically in the second cylinder chamber. This causes fluid to be drawn into the first cylinder chamber and compressed.

[0005] An example of such a two-cylinder rotary compressor is disclosed in Patent Document 1.

[0006] JP 2014-196714 A

[0007] In rotary compressors such as those described above, there is a demand for reducing the distance between the first and second heads, which are the support points of the drive shaft, to reduce the diameter of the drive shaft and improve reliability, thereby suppressing deflection of the drive shaft. One possible solution is to make the middle plate thinner. However, if the middle plate is made too thin, its strength decreases, and it may be deflected and deformed by the pressure of the fluid compressed in the first and second cylinder chambers. This could cause the middle plate to come into contact with the first or second roller, compromising the reliability of the rotary compressor.

[0008] An object of the present disclosure is to improve reliability when the diameter of the drive shaft of a rotary compressor is reduced.

[0009] A first aspect of the present disclosure relates to a rotary compressor (10). The rotary compressor (10) of the first aspect includes a compression mechanism (30) having a stacked structure including a first head (31), a first cylinder (35), a middle plate (38), a second cylinder (40), and a second head (43), and a drive shaft (25) disposed to penetrate the compression mechanism (30) in the stacking direction and rotatably supported by the first head (31) and the second head (43). A first cylinder chamber (37) defined by the first head (31) and the middle plate (38) is formed inside the first cylinder (35). A first piston (50) is accommodated in the first cylinder chamber (37), and the first piston (50) rotates eccentrically in response to rotation of the drive shaft (25) to compress fluid drawn into the first cylinder chamber (37). A second cylinder chamber (42) defined by the middle plate (38) and the second head (43) is formed inside the second cylinder (40). A second piston (60) is accommodated in the second cylinder chamber (42), and the second piston (60) rotates eccentrically with the rotation of the drive shaft (25) to compress the fluid drawn into the second cylinder chamber (42). The diameters Ds of both the first cylinder chamber (37) and the second cylinder chamber (42) or the smaller diameter Ds, and the thickness Tm of the middle plate (38) satisfy the relational expression 1 / 30≦Tm / Ds≦1 / 10.

[0010] In this first aspect, the thickness Tm of the middle plate (38) is 1 / 30 to 1 / 10 of the diameter Ds of both the first cylinder chamber (37) and the second cylinder chamber (42), or the smaller diameter Ds. When the thickness Tm of the middle plate (38) is 1 / 30 or more of the diameter Ds of a specific cylinder chamber (the first cylinder chamber (37) or the second cylinder chamber (42)), bending of the middle plate (38) due to the pressure of the fluid compressed in the cylinder chamber can be suitably suppressed. Furthermore, when the thickness Tm of the middle plate (38) is 1 / 10 or less of the diameter Ds of the specific cylinder chamber, the distance between the first head (31) and the second head (43) can be reduced. This suppresses bending of the drive shaft (25). Therefore, reliability can be improved when the diameter of the drive shaft (25) of the rotary compressor (10) is reduced.

[0011] A second aspect of the present disclosure is the rotary compressor (10) of the first aspect, further comprising: a casing (11) that houses the compression mechanism (30) and the drive shaft (25), a first suction pipe (15) that draws fluid into the first cylinder chamber (37), and a second suction pipe (16) that draws fluid into the second cylinder chamber (42). The first suction pipe (15) and the second suction pipe (16) each penetrate the casing (11). The distance L1 between the center (C1) of the portion of the first suction pipe (15) that penetrates the casing (11) and the center (C2) of the portion of the second suction pipe (16) that penetrates the casing (11), and the distance L2 between the center (C3) in the height direction of the first cylinder chamber (37) and the center (C4) in the height direction of the second cylinder chamber (42) satisfy the relational expression L1 > L2.

[0012] In the second aspect, the distance L1 between the centers (C1, C2) of the first and second suction pipes (15) and (16) at their portions passing through the casing (11) is greater than the distance L2 between the centers (C3, C4) of the first and second cylinder chambers (37) and (42) in the height direction, thereby ensuring the strength of the portions of the casing (11) through which the first and second suction pipes (15) and (16) pass.

[0013] A third aspect of the present disclosure is the rotary compressor (10) of the first or second aspect, wherein the first piston (50) and the second piston (60) are eccentric with respect to the axis (AC) of the drive shaft (25). An eccentric distance Le of the first piston (50) or the second piston (60) associated with the diameter Ds satisfying the relational expression of the first aspect, and a radius Rs of the first cylinder chamber (37) formed inside the first piston (50) or a radius Rs of the second cylinder chamber (42) formed inside the second piston (60) satisfy a relational expression expressed by Le / Rs≦0.25.

[0014] In the third aspect, the ratio (Le / Rs) of the eccentric distance Le of the first piston (50) to the radius Rs of the first cylinder chamber (37) or the ratio (Le / Rs) of the eccentric distance Le of the second piston (60) to the radius Rs of the second cylinder chamber (42), which is related to the diameter Ds that satisfies the relational expression of the first aspect, is 0.25 or less. This makes it possible to suitably suppress the amount of deflection of the middle plate (38) based on a calculation formula for the deflection and stress of a perforated disk, and to make the amount of deflection small relative to the thickness of the middle plate (38). This is advantageous for improving the reliability of the rotary compressor (10).

[0015] A fourth aspect of the present disclosure is the rotary compressor (10) of any one of the first to third aspects, wherein the first suction pipe (15) is connected to the first head (31) or the second suction pipe (16) is connected to the second head (43).

[0016] In the fourth aspect, the first suction pipe (15) is connected to the first head (31), or the second suction pipe (16) is connected to the second head (43). This makes it possible to easily realize a configuration in which the distance between the centers (C1, C2) of the first suction pipe (15) and the second suction pipe (16) at the portions thereof passing through the casing (11) is greater than the distance between the centers (C1, C2) of the first cylinder chamber (37) and the second cylinder chamber (42) in the height direction.

[0017] A fifth aspect of the present disclosure is the rotary compressor (10) of any one of the first to third aspects, wherein the first suction pipe (15) is connected to the first head (31) and the second suction pipe (16) is connected to the second cylinder (40), or the first suction pipe (15) is connected to the first cylinder (35) and the second suction pipe (16) is connected to the second head (43).

[0018] In the fifth aspect, the first suction pipe (15) is connected to the first head (31) and the second suction pipe (16) is connected to the second cylinder (40), or the first suction pipe (15) is connected to the first cylinder (35) and the second suction pipe (16) is connected to the second head (43). This specifically realizes a configuration in which the distance between the centers (C1, C2) of the first suction pipe (15) and the second suction pipe (16) at their portions passing through the casing (11) is greater than the distance between the centers (C3, C4) of the first cylinder chamber (37) and the second cylinder chamber (42) in the height direction. Furthermore, since the first suction pipe (15) is connected to the first cylinder (35) or the second suction pipe (16) is connected to the second cylinder (40), the flow path of the fluid sent to the compression mechanism (30) via the first suction pipe (15) and the second suction pipe (16) to reach the first cylinder chamber (37) or the second cylinder chamber (42) can be made shorter, thereby reducing the pressure loss of the fluid, compared to when the first suction pipe (15) is connected to the first header (31) and the second suction pipe (16) is connected to the second header (43).

[0019] A sixth aspect of the present disclosure is the rotary compressor (10) of any one of the first to fifth aspects, further including an electric motor (21) coupled to the drive shaft (25). The electric motor (21) is disposed at a position where the electric motor (21) is positioned between the electric motor and the first cylinder (35) via the first head (31). The drive shaft (25) has a main shaft portion (26) supported by the first head (31). The diameter Ds that satisfies the relational expression of the first aspect and the diameter Da of the main shaft portion (26) satisfy the relational expression Da≦Ds×0.35.

[0020] In the sixth aspect, the diameter Da of the main shaft portion (26) of the drive shaft (25) supported by the first head (31) is 0.35 times or less the diameter Ds of the first cylinder chamber (37) or the second cylinder chamber (42) that satisfies the relational expression of the first aspect. When the diameter Da of the main shaft portion (26) is relatively small, friction loss between the main shaft portion (26) and the first head (31) can be reduced. This can improve the compression efficiency of the rotary compressor (10). On the other hand, a drive shaft (25) having a relatively small diameter main shaft portion (26) is prone to bending during operation of the rotary compressor (10). The technology of the present disclosure is particularly effective for a rotary compressor (10) including such a drive shaft (25) because it can suppress bending of the drive shaft (25).

[0021] A seventh aspect of the present disclosure is the rotary compressor (10) of any one of the first to sixth aspects, further including an electric motor (21) coupled to the drive shaft (25). The electric motor (21) is disposed at a position between the electric motor (21) and the first cylinder (35) with the first head (31) interposed therebetween. The drive shaft (25) has a main shaft (26) supported by the first head (31) and a counter shaft (29) supported by the second head (43). A diameter Db of the counter shaft (29) and a diameter Da of the main shaft (26) satisfy the relational expression Db<Da.

[0022] In the seventh aspect, the diameter Db of the countershaft (29) of the drive shaft (25), which is supported by the second head (43), is smaller than the diameter Da of the main shaft (26) which is supported by the first head (31). When the diameter Db of the countershaft (29) is smaller than the diameter Da of the main shaft (26), the friction loss between the countershaft (29) and the second head (43) can be reduced compared to when the diameter Db of the countershaft (29) is the same as the diameter Da of the main shaft (26). This is advantageous for increasing the compression efficiency of the rotary compressor (10).

[0023] An eighth aspect of the present disclosure is the rotary compressor (10) of any one of the first to seventh aspects, wherein a bearing hole (33, 45) through which the drive shaft (25) is inserted is formed in the first head (31) and the second head (43). An annular groove (34, 46) extending along the periphery of the bearing hole (33, 45) is formed in an end surface of the first head (31) or the second head (43) on the side of the middle plate (38).

[0024] In the eighth aspect, an annular groove (34, 46) is formed in an end surface of the first head (31) or the second head (43) on the side of the middle plate (38). This allows an elastically deformable bearing portion (32, 44) to be formed between the annular groove (34, 46) and the through hole (72) in the first head (31) or the second head (43). During operation of the rotary compressor (10), the pressure of the fluid compressed in the first cylinder chamber (37) acts on the first piston (50), and the pressure of the fluid compressed in the second cylinder chamber (42) acts on the second piston (60). This compressive load is applied to the drive shaft (25), causing the drive shaft (25) to bend in the radial direction. When the drive shaft (25) bends, the bearings (32, 44) elastically deform toward the annular grooves (34, 46) in response to the bending of the drive shaft (25), and bend together with the drive shaft (25). This prevents the drive shaft (25) from coming into strong, one-sided contact with the bearings (32, 44) of the first head (31) or the second head (43), thereby reducing wear between the drive shaft (25) and the bearings (32, 44).

[0025] A ninth aspect of the present disclosure is the rotary compressor (10) according to any one of the first to eighth aspects, wherein the maximum rotation speed of the drive shaft (25) is 120 rps or more.

[0026] In the ninth aspect, the maximum rotation speed of the drive shaft (25) is relatively high, at 120 rps or more. The higher the rotation speed of the drive shaft (25), the greater the tendency for the drive shaft (25) to bend. The technique of the present disclosure is particularly effective in a rotary compressor (10) operated at such a relatively high rotation speed, since it can suppress bending of the drive shaft (25).

[0027] A tenth aspect of the present disclosure is directed to a refrigeration system (1). The refrigeration system (1) of the tenth aspect includes the rotary compressor (10) of any one of the first to ninth aspects.

[0028] In the tenth aspect, the refrigeration system (1) includes a rotary compressor (10) according to the technique of the present disclosure. The rotary compressor (10) improves reliability when the diameter of the drive shaft (25) of the rotary compressor (10) is reduced. The rotary compressor (10) improves compression efficiency by reducing the diameter of the drive shaft (25), thereby improving energy efficiency while maintaining reliability of the refrigeration system (1).

[0029] FIG. 1 is a refrigerant circuit diagram illustrating the configuration of a refrigeration device according to an embodiment. FIG. 2 is a longitudinal cross-sectional view illustrating the configuration of a rotary compressor. FIG. 3 is a longitudinal cross-sectional view illustrating a main portion of a rotary compressor. FIG. 4 is a transverse cross-sectional view illustrating the configuration of a first cylinder and a first piston. FIG. 5 is a transverse cross-sectional view illustrating the configuration of a second cylinder and a second piston. FIG. 6 is a schematic diagram illustrating a simplified model of the configuration of a first cylinder chamber and a first piston, and the configuration of a second cylinder chamber and a second piston. FIG. 7 is a schematic diagram illustrating a structural model for a calculation formula relating to the deflection and stress of a perforated disk. FIG. 8 is a graph illustrating an index value (y ) indicating the deflection amount of the middle plate relative to the ratio (Ds / Tm) of the diameter of the first cylinder chamber or the second cylinder chamber to the thickness of the middle plate. ｍａｘ / t). Fig. 9 is a graph illustrating the relationship between the ratio (Ds / Tm) of the diameter of the first cylinder chamber or the second cylinder chamber to the thickness of the middle plate and the amount of deflection of the middle plate. Fig. 10 is a longitudinal sectional view illustrating a main part of a rotary compressor of a first modified example. Fig. 11 is a longitudinal sectional view illustrating a main part of a rotary compressor of a second modified example. Fig. 12 is a longitudinal sectional view illustrating a main part of a rotary compressor of a third modified example. Fig. 13 is a transverse sectional view illustrating a configuration of a first cylinder and a first piston of another embodiment.

[0030] Exemplary embodiments will be described in detail below with reference to the drawings. In the following embodiments, a rotary compressor according to the present disclosure is applied to a refrigeration system. The drawings are intended to conceptually explain the technology of the present disclosure. Therefore, in the drawings, dimensions, ratios, or numbers may be exaggerated or simplified to facilitate understanding of the technology of the present disclosure.

[0031] In the following embodiments, the direction along the axis of the drive shaft of the rotary compressor is referred to as the "axial direction," the direction perpendicular to the axial direction is referred to as the "radial direction," and the direction along the periphery of the drive shaft is referred to as the "circumferential direction." Furthermore, the terms "first," "second," etc. are used to distinguish between terms to which these terms are attached, and do not limit the number of terms or any order thereof.

[0032] <Embodiment> As shown in FIG. 1, a rotary compressor (10) of this embodiment is provided in a refrigeration system (1).

[0033] - Refrigeration Device - The refrigeration device (1) includes a refrigerant circuit (1a). The refrigerant circuit (1a) is filled with a refrigerant. The refrigerant is an example of a fluid compressed by a rotary compressor (10). The refrigerant circuit (1a) includes the rotary compressor (10), a radiator (3), a pressure reduction mechanism (4), and an evaporator (5). The pressure reduction mechanism (4) is, for example, an expansion valve. The refrigerant circuit (1a) performs a vapor compression refrigeration cycle.

[0034] In the refrigeration cycle, the rotary compressor (10) draws in and compresses low-pressure gas refrigerant, and discharges it as high-pressure gas refrigerant. The high-pressure gas refrigerant compressed by the rotary compressor (10) dissipates heat to the air in the radiator (3). At this time, the refrigerant is liquefied and changes into liquid refrigerant. The liquid refrigerant that has dissipated heat is depressurized by the depressurization mechanism (4). The depressurized liquid refrigerant evaporates in the evaporator (5). At this time, the refrigerant vaporizes and changes into low-pressure gas refrigerant. The low-pressure gas refrigerant produced in the evaporator (5) is drawn into the rotary compressor (10).

[0035] The refrigeration system (1) is an air conditioner. The air conditioner may be a dual-purpose air conditioner that switches between cooling and heating. In this case, the air conditioner has a switching mechanism that switches the refrigerant circulation direction. The switching mechanism is, for example, a four-way switching valve. The air conditioner may be a dedicated cooling or heating unit. The refrigeration system (1) may also be a water heater, a chiller unit, a cooling device that cools the air inside a storage unit, or the like. A cooling device is a device that cools the air inside a water heater, refrigerator, freezer, container, or the like.

[0036] -Rotary Compressor- As shown in Figure 2, the rotary compressor (10) is a two-cylinder rotary compressor. The maximum rotation speed of the rotary compressor (10) is 120 rps or more. The "maximum rotation speed" here refers to the rotation speed of the drive shaft (25) caused by the operation of the electric motor (21), and means the highest rotation speed that can occur within the operating range of the product. Increasing the maximum rotation speed of the rotary compressor (10) is preferable for increasing the amount of refrigerant circulating in the refrigerant circuit (1a) and ensuring the maximum amount of refrigerant circulating.

[0037] The rotary compressor (10) includes a casing (11), a drive mechanism (20), and a compression mechanism (30). The drive mechanism (20) and the compression mechanism (30) are housed inside the casing (11).

[0038] <Casing> The casing (11) is composed of a vertically long, cylindrical, sealed container with both ends closed. The casing (11) is installed in an upright position. The casing (11) has a body (12), a lower head plate (13), and an upper head plate (14). The body (12) is formed in a cylindrical shape extending vertically. The lower head plate (13) is fixed to the lower end of the body (12) and closes the lower end opening. The upper head plate (14) is fixed to the upper end of the body (12) and closes the upper end opening.

[0039] A first suction pipe (15) and a second suction pipe (16) are fixed to the body portion (12). The first suction pipe (15) and the second suction pipe (16) each pass through the body portion (12) and are connected to the compression mechanism (30). In this embodiment, the first suction pipe (15) is connected to the first cylinder (35), and the second suction pipe (16) is connected to the rear head (43). A discharge pipe (17) is fixed to the upper head (14). The discharge pipe (17) passes through the upper head (14) and opens into an upper space inside the casing (11).

[0040] An oil reservoir (18) is provided at the bottom of the casing (11). The oil reservoir (18) is formed by the inner walls of the lower part of the body (12) and the lower head (13). Oil is stored in the oil reservoir (18). This oil serves to lubricate the sliding parts of the compression mechanism (30) and the drive shaft (25).

[0041] <Drive Mechanism> The drive mechanism (20) has an electric motor (21) and a drive shaft (25). The electric motor (21) is arranged above the compression mechanism (30). The electric motor (21) is provided at a position with the front head (31) interposed between the electric motor (21) and the first cylinder (35). The electric motor (21) has a stator (22) and a rotor (23). The stator (22) and the rotor (23) are each formed in a cylindrical shape. The stator (22) is fixed to the inner circumferential surface of the body portion (12) of the casing (11). The rotor (23) is arranged in a hollow portion of the stator (22).

[0042] The drive shaft (25) is inserted into the hollow portion of the rotor (23). The rotor (23) is fixed to the drive shaft (25). When the electric motor (21) is energized, the drive shaft (25) rotates integrally with the rotor (23). The drive shaft (25) is a shaft body that drives the compression mechanism (30). The drive shaft (25) is disposed on the axis of the body portion (12) of the casing (11) and extends vertically inside the casing (11). The drive shaft (25) has a main shaft portion (26), a first eccentric portion (27), a second eccentric portion (28), and a counter shaft portion (29).

[0043] An upper portion of the main shaft portion (26) is fixed to the rotor (23). Both the first eccentric portion (27) and the second eccentric portion (28) are provided at a lower portion of the main shaft portion (26). The first eccentric portion (27) is disposed above the second eccentric portion (28). The first eccentric portion (27) and the second eccentric portion (28) are each formed to have a larger diameter than the main shaft portion (26). The first eccentric portion (27) and the second eccentric portion (28) are eccentric by a predetermined distance from the axis (AC) of the main shaft portion (26). The first eccentric portion (27) and the second eccentric portion (28) are eccentric to opposite sides of the axis (AC) of the drive shaft (25).

[0044] The drive shaft (25) is disposed to pass through the compression mechanism (30). The portion of the main shaft (26) above the first eccentric portion (27) is rotatably supported by a front head (31) included in the compression mechanism (30). The countershaft (29) constitutes the portion of the drive shaft (25) below the second eccentric portion (28), and is rotatably supported by a rear head (43) included in the compression mechanism (30). In this example, the diameter Db of the countershaft (29) is approximately the same as the diameter Da of the main shaft (26) (Da = Db, or Da ≈ Db) (see FIG. 3 ).

[0045] An oil passage (25a) is formed inside the drive shaft (25). The oil passage (25a) extends to the compression mechanism (30) and the sliding portions of the drive shaft (25). An oil supply pump (25b) is provided at the lower end of the drive shaft (25) (countershaft portion (29)). The oil supply pump (25b) is immersed in the oil in the oil reservoir (18) and transports oil as the drive shaft (25) rotates. The transported oil is supplied to the compression mechanism (30) and the sliding portions of the drive shaft (25) through the oil passage (25a).

[0046] <Compression Mechanism> The compression mechanism (30) is a mechanism for sucking in and compressing a refrigerant, and is disposed below the electric motor (21). The compression mechanism (30) includes a front head (31), a first cylinder (35), a middle plate (38), a second cylinder (40), and a rear head (43). The front head (31), the first cylinder (35), the middle plate (38), the second cylinder (40), and the rear head (43) are made of metal such as cast iron. The front head (31) is an example of a first head. The rear head (43) is an example of a second head.

[0047] 3, the compression mechanism (30) has a structure in which a front head (31), a first cylinder (35), a middle plate (38), a second cylinder (40), and a rear head (43) are stacked one on top of the other. The front head (31), the first cylinder (35), the middle plate (38), the second cylinder (40), and the rear head (43) are stacked in order from top to bottom and fixed by bolts (70).

[0048] Specifically, a threaded hole (71) is formed in the front head (31). A through hole (72) is formed in each of the first cylinder (35), the middle plate (38), the second cylinder (40), and the rear head (43) at a position corresponding to the threaded hole (71). A bolt (70) is inserted from the rear head (43) side to fasten the front head (31), the first cylinder (35), the middle plate (38), the second cylinder (40), and the rear head (43) together.

[0049] The front head (31) is an end plate member forming an upper cover of the first cylinder (35). The front head (31) is fixed to the body (12) of the casing (11). The front head (31) is stacked on top of the first cylinder (35). The front head (31) is arranged so as to cover the hollow portion of the first cylinder (35) from above. The front head (31) forms the upper surface of the first cylinder chamber (37).

[0050] A first bearing portion (32) is provided in the center of the front head (31). The first bearing portion (32) is cylindrical and protrudes upward. The first bearing portion (32) constitutes a plain bearing. A first bearing hole (33) is formed in the first bearing portion (32). The first bearing hole (33) is a circular hole that passes through the front head (31). The main shaft portion (26) of the drive shaft (25) is inserted into the first bearing hole (33).

[0051] A first annular groove (34) is formed in the end face of the front head (31) on the side of the middle plate (38), i.e., in this example, the lower face. The first annular groove (34) extends annularly along the periphery of the first bearing hole (33). A portion of the first bearing portion (32) between the first annular groove (34) and the first bearing hole (33) is configured to be elastically deformable. By means of this first bearing portion (32), the front head (31) rotatably supports the main shaft portion (26) of the drive shaft (25).

[0052] The first cylinder (35) is a thick, substantially annular member. A first cylinder hole (36) is formed in the center of the first cylinder (35). The first cylinder hole (36) is a circular hole that penetrates the first cylinder (35) in the thickness direction. The first cylinder (35) is oriented such that the center line of the first cylinder hole (36) faces the axial direction (vertical direction). Openings at both ends of the first cylinder hole (36) are closed by the front head (31) and the middle plate (38).

[0053] A first cylinder chamber (37) is formed inside the first cylinder (35). The first cylinder chamber (37) is formed by a first cylinder bore (36) and is a space surrounded by the inner circumferential surface of the first cylinder (35), the lower surface of the front head (31), and the upper surface of the middle plate (38). The outer circumferential boundary of the first cylinder chamber (37) is defined by the inner circumferential surface of the first cylinder (35). Both axial boundaries of the first cylinder chamber (37) are defined by the lower surface of the front head (31) and the upper surface of the middle plate (38).

[0054] The middle plate (38) is a substantially annular plate member and is sandwiched between the first cylinder (35) and the second cylinder (40). A shaft through hole (39) is formed in the center of the middle plate (38). The shaft through hole (39) is a circular hole that penetrates the middle plate (38) in the thickness direction. A portion of the main shaft portion (26) of the drive shaft (25) between the first eccentric portion (27) and the second eccentric portion (28) is inserted into the shaft through hole (39).

[0055] The middle plate (38) is arranged so as to cover the hollow portion (first cylinder bore (36)) of the first cylinder (35) from below. The middle plate (38) is arranged so as to cover the hollow portion (second cylinder bore (41)) of the second cylinder (40) from above. The upper surface of the middle plate (38) forms the lower surface of the first cylinder chamber (37). The lower surface of the middle plate (38) forms the upper surface of the second cylinder chamber (42).

[0056] The second cylinder (40) is a thick, substantially annular member. A second cylinder hole (41) is formed in the center of the second cylinder (40). The second cylinder hole (41) is a circular hole that penetrates the second cylinder (40) in the thickness direction. The second cylinder (40) is oriented such that the center line of the second cylinder hole (41) faces the axial direction (vertical direction). Openings at both ends of the second cylinder hole (41) are closed by the middle plate (38) and the rear head (43).

[0057] A second cylinder chamber (42) is formed inside the second cylinder (40). The second cylinder chamber (42) is formed by the second cylinder bore (41) and is a space surrounded by the inner circumferential surface of the second cylinder (40), the lower surface of the middle plate (38), and the upper surface of the rear head (43). The outer circumferential boundary of the second cylinder chamber (42) is defined by the inner circumferential surface of the second cylinder (40). Both axial boundaries of the second cylinder chamber (42) are defined by the lower surface of the middle plate (38) and the upper surface of the rear head (43).

[0058] The rear head (43) is an end plate member forming a lower cover of the second cylinder (40). The rear head (43) is stacked on the lower part of the second cylinder (40). The rear head (43) is arranged so as to cover the hollow part (second cylinder hole (41)) of the second cylinder (40) from below. The rear head (43) forms the lower surface of the second cylinder chamber (42).

[0059] A second bearing portion (44) is provided in the center of the rear head (43). The second bearing portion (44) is cylindrical and protrudes downward. The second bearing portion (44) constitutes a plain bearing. A second bearing hole (45) is formed in the second bearing portion (44). The second bearing hole (45) is a circular hole that passes through the rear head (43). The countershaft portion (29) of the drive shaft (25) is inserted into the second bearing hole (45).

[0060] A second annular groove (46) is formed in the end surface of the rear head (43) on the side of the middle plate (38), i.e., in this example, the upper surface. The second annular groove (46) extends annularly along the periphery of the second bearing hole (45). The portion of the second bearing portion (44) between the second annular groove (46) and the second bearing hole (45) is configured to be elastically deformable. By means of this second bearing portion (44), the rear head (43) rotatably supports the countershaft portion (29) of the drive shaft (25).

[0061] As shown in FIG. 4 , a first bushing hole (47) and a first blade hole (48) are formed in the first cylinder (35). The first bushing hole (47) and the second blade hole (58) penetrate the first cylinder (35) in the axial direction (thickness direction). The first bushing hole (47) and the first blade hole (48) are each formed in a substantially circular shape. The first bushing hole (47) opens radially into the first cylinder hole (36). The first blade hole (48) is located radially outward of the first bushing hole (47) and communicates with the first bushing hole (47).

[0062] A pair of first bushes (49) are fitted into the first bush holes (47). Each first bush (49) is a semi-cylindrical member. The flat surfaces of the pair of first bushes (49) face each other with a gap therebetween. The pair of first bushes (49) are oscillating about the center line of the first bush hole (47) as their axis. The pair of first bushes (49) restrict the rotation of the first piston (50) by sandwiching a first blade (52) described below between them.

[0063] The first cylinder chamber (37) accommodates a first piston (50). The first piston (50) includes a first roller (51) and a first blade (52). The first roller (51) is an annular member. The first eccentric portion (27) of the drive shaft (25) is fitted into the hollow portion of the first roller (51). The outer peripheral surface of the first roller (51) contacts the inner peripheral surface of the first cylinder (35) so as to be able to slide in the circumferential direction. The first roller (51) rotates integrally with the first eccentric portion (27). A predetermined first gap (not shown) is formed between the first roller (51) and the lower surface of the front head (31) or the upper surface of the middle plate (38). The first gap is, for example, 10 μm or less.

[0064] The first blade (52) is provided on the outer peripheral surface of the first roller (51) and extends radially outward from the first roller (51). The first blade (52) is sandwiched between a pair of first bushings (49) so as to be movable forward and backward. The tip of the first blade (52) is housed in the first blade hole (48). In the first cylinder chamber (37), a first working space (53) for compressing refrigerant is formed between the outer peripheral surface of the first roller (51) and the inner peripheral surface of the first cylinder (35). The first working space (53) is divided into a first low-pressure chamber and a first high-pressure chamber by the first blade (52).

[0065] A first suction passage (54) is formed in the first cylinder (35). The first suction passage (54) penetrates the first cylinder (35) in the radial direction. One end of the first suction passage (54) opens at a position adjacent to the first bush (49) on the inner circumferential surface of the first cylinder (35) (a position immediately to the right of the first bush (49) in FIG. 4 ) and communicates with the first low-pressure chamber. The other end of the first suction passage (54) opens at the outer circumferential surface of the first cylinder (35) and constitutes an inlet end. The first suction pipe (15) is connected to the inlet end of the first suction passage (54) (see FIG. 3 ).

[0066] A first discharge passage (55) is formed in the front head (31). The first discharge passage (55) axially penetrates the front head (31). One end of the first discharge passage (55) opens at a position on the underside of the front head (31) relative to the first bush (49) on the opposite side from the first suction passage (54) (a position adjacent to the left of the first bush (49) in FIG. 4 ), and communicates with the first high-pressure chamber. The other end of the first discharge passage (55) opens at the top surface of the front head (31).

[0067] A first discharge valve (56) is provided on the upper surface of the front head (31). The first discharge valve (56) opens and closes the first discharge passage (55). The first discharge valve (56) is configured, for example, by a reed valve. The first discharge valve (56) is in a closed state that closes the first discharge passage (55) while the gas pressure in the first high-pressure chamber is lower than the gas pressure (dome pressure) in the casing (11). When the gas pressure in the first high-pressure chamber exceeds the dome pressure, the first discharge valve (56) is in an open state that opens the first discharge passage (55).

[0068] As shown in FIG. 5 , a second bushing hole (57) and a second blade hole (58) are formed in the second cylinder (40). The second bushing hole (57) and the second blade hole (58) penetrate the second cylinder (40) in the axial direction (thickness direction). The second bushing hole (57) and the second blade hole (58) are each formed in a substantially circular shape. The second bushing hole (57) opens into the second cylinder hole (41). The second blade hole (58) is located outside the second bushing hole (57) in the radial direction of the second cylinder (40) and communicates with the second bushing hole (57).

[0069] A pair of second bushes (59) are fitted into the second bush holes (57). Each second bush (59) is a semi-cylindrical member. The flat surfaces of the pair of second bushes (59) face each other with a gap therebetween. The pair of second bushes (59) are oscillating about the center line of the second bush hole (57) as their axis. The pair of second bushes (59) restrict the rotation of the second piston (60) by sandwiching a second blade (62) described below between them.

[0070] The second cylinder chamber (42) accommodates a second piston (60). The second piston (60) includes a second roller (61) and a second blade (62). The second roller (61) is an annular member. The second eccentric portion (28) of the drive shaft (25) is fitted into the hollow portion of the second roller (61). The outer circumferential surface of the second roller (61) contacts the inner circumferential surface of the second cylinder (40) so as to be able to slide in the circumferential direction. The second roller (61) rotates integrally with the second eccentric portion (28). A predetermined second gap (not shown) is formed between the second roller (61) and the lower surface of the middle plate (38) or the upper surface of the rear head (43). The second gap is, for example, 10 μm or less.

[0071] The second blade (62) is provided on the outer peripheral surface of the second roller (61) and extends radially outward from the second roller (61). The second blade (62) is movably held between a pair of second bushings (59). The tip of the second blade (62) is housed in the second blade hole (58). In the second cylinder chamber (42), a second working space (63) for compressing refrigerant is formed between the outer peripheral surface of the first roller (51) and the inner peripheral surface of the first cylinder (35). The second working space (63) is partitioned by the first blade (52) into a second low-pressure chamber and a second high-pressure chamber.

[0072] A second suction passage (64) is formed in the second cylinder (40) and the rear head (43). The second suction passage (64) includes a cylinder-side passage (65) formed in the second cylinder (40) and a head-side passage (66) formed in the rear head (43).

[0073] The cylinder-side passage (65) extends radially through the second cylinder (40). One end of the cylinder-side passage (65) opens at a position adjacent to the second bush (59) on the inner circumferential surface of the second cylinder (40) (at a position immediately to the right of the second bush (59) in FIG. 5 ), and communicates with the second low-pressure chamber. The other end of the cylinder-side passage (65) opens at a surface on the rear head (43) side (the lower surface in FIG. 3 ), and constitutes an inlet end. The head-side passage (66) extends radially through the rear head (43). As shown in FIG. 3 , the head-side passage (66) has a first passage (66a) and a second passage (66b).

[0074] The first passage (66a) extends radially outward from the rear head (43). One end of the first passage (66a) opens into the outer peripheral surface of the rear head (43) and constitutes an inlet end. The second suction pipe (16) is connected to the inlet end of the first passage (66a). The second passage (66b) is provided on the other end side of the first passage (66a). The second passage (66b) extends axially upward from the first passage (66a). One end of the second passage (66b) opens into the upper surface of the rear head (43) and constitutes an outlet end. The outlet end of the second passage (66b) corresponds to the inlet end of the cylinder-side passage (65) and communicates with the second cylinder chamber (42) via the cylinder-side passage (65).

[0075] With this configuration, the distance between the first suction pipe (15) and the second suction pipe (16) can be increased compared to when the second suction pipe (16) is connected to the second cylinder (40). A distance L1 between the center (C1) of the first suction pipe (15) at the portion where it penetrates the body (12) of the casing (11) and the center (C2) of the second suction pipe (16) at the portion where it penetrates the body (12) of the casing (11), and a distance L2 between the center (C3) in the height direction of the first cylinder chamber (37) and the center (C4) in the height direction of the second cylinder chamber (42) satisfy the relational expression expressed by the following formula (1): L1>L2 (1)

[0076] As shown in Figure 5, the rear head (43) is further formed with a second discharge passage (67). The second discharge passage (67) axially penetrates the rear head (43). One end of the second discharge passage (67) opens at a position on the upper surface of the rear head (43) relative to the second bush (59) on the opposite side from the second suction passage (64) (to the left of the second bush (59) in Figure 5), and communicates with the second high-pressure chamber. The other end of the second discharge passage (67) opens at the lower surface of the rear head (43).

[0077] A second discharge valve (68) is provided on the lower surface of the rear head (43). The second discharge valve (68) opens and closes the second discharge passage (67). The second discharge valve (68) is configured, for example, by a reed valve. The second discharge valve (68) is in a closed state that closes the second discharge passage (67) while the gas pressure in the second high-pressure chamber is lower than the pressure in the dome. On the other hand, when the gas pressure in the second high-pressure chamber exceeds the pressure in the dome, the second discharge valve (68) is in an open state that opens the second discharge passage (67).

[0078] In the compression mechanism (30), the first piston (50) rotates eccentrically in the first cylinder chamber (37) as the drive shaft (25) rotates. As the volume of the first low-pressure chamber gradually increases with the eccentric rotation of the first piston (50), refrigerant flowing through the first suction pipe (15) is sucked into the first low-pressure chamber from the first suction passage (54). As the first piston (50) continues to rotate eccentrically, the first low-pressure chamber is isolated from the first suction passage (54), and the isolated space forms a first high-pressure chamber.

[0079] As the volume of the first high-pressure chamber gradually decreases due to further eccentric rotation of the first piston (50), the gas pressure in the first high-pressure chamber increases. When the gas pressure in the first high-pressure chamber exceeds the pressure in the dome, the first discharge valve (56) opens, and the refrigerant in the first high-pressure chamber flows out of the compression mechanism (30) through the first discharge passage (55).

[0080] Furthermore, as the drive shaft (25) rotates, the first piston (50) rotates eccentrically and the second piston (60) rotates eccentrically in the second cylinder chamber (42). As the volume of the second low-pressure chamber gradually increases with the eccentric rotation of the second piston (60), refrigerant flowing through the second suction pipe (16) is sucked into the second low-pressure chamber from the second suction passage (64). As the second piston (60) continues to rotate eccentrically, the second low-pressure chamber is isolated from the second suction passage (64), and the isolated space forms a second high-pressure chamber.

[0081] As the volume of the second high-pressure chamber gradually decreases due to further eccentric rotation of the second piston (60), the gas pressure in the second high-pressure chamber increases. When the gas pressure in the second high-pressure chamber exceeds the pressure in the dome, the second discharge valve (68) opens, and the refrigerant in the second high-pressure chamber flows out of the compression mechanism (30) through the second discharge passage (67).

[0082] The high-pressure refrigerant that has flowed out of the compression mechanism (30) flows upward in the internal space of the casing (11) and passes through a core cut (not shown) of the stator (22), etc. Then, the high-pressure refrigerant that has flowed above the electric motor (21) is sent to the refrigerant circuit (1a) through the discharge pipe (17).

[0083] <Accumulator> As shown in Fig. 2, an accumulator (80) is connected upstream of the rotary compressor (10). The accumulator (80) temporarily stores the refrigerant before it is sucked into the rotary compressor (10) and separates the liquid refrigerant and oil contained in the gas refrigerant into gas and liquid. The accumulator (80) has a sealed container (81), an inlet pipe (82), a first outlet pipe (83), and a second outlet pipe (84).

[0084] The sealed container (81) is formed of a vertically long cylindrical member. The inlet pipe (82) is a pipe body that allows the refrigerant to flow into the sealed container (81). The inlet pipe (82) is connected to the upper part of the sealed container (81). The lower end of the inlet pipe (82) opens at a position near the upper part of the internal space of the sealed container (81). The upper end of the inlet pipe (82) is connected to the refrigerant circuit (1a).

[0085] The first outlet pipe (83) and the second outlet pipe (84) are pipes that allow the refrigerant to flow out of the sealed container (81). The first outlet pipe (83) and the second outlet pipe (84) are connected to the lower part of the sealed container (81). The upper ends of the first outlet pipe (83) and the second outlet pipe (84) extend in the vertical direction within the sealed container (81) and open at positions near the upper part of the internal space of the sealed container (81).

[0086] The lower end of the first outlet pipe (83) extends downward from the lower end of the sealed container (81), then bends toward the first suction pipe (15) of the rotary compressor (10), and is connected to the first suction pipe (15). The lower end of the second outlet pipe (84) extends downward from the lower end of the sealed container (61), then bends toward the second suction pipe (16) of the rotary compressor (10), and is connected to the second suction pipe (16).

[0087] <Various Designs Related to Diameters or Radii of First and Second Cylinder Chambers> The thickness Tm of the middle plate (38), the diameter Da of the main shaft portion (26), the eccentric distance Le1 of the first piston (50), and the eccentric distance Le2 of the second piston (60) are designed based on the diameter Ds1 of the first cylinder chamber (37) or the diameter Ds2 of the second cylinder chamber (42), respectively. As shown in Fig. 3 , the diameter Ds1 of the first cylinder chamber (37) and the diameter Ds2 of the second cylinder chamber (42) are the same. Hereinafter, the diameter Ds1 of the first cylinder chamber (37) and the diameter Ds2 of the second cylinder chamber (42) will not be distinguished from each other and will be referred to as the diameter Ds.

[0088] The outer diameter of the first piston (50) and the outer diameter of the second piston (60) are the same. The eccentric distance Le1 of the first piston (50) and the eccentric distance Le2 of the second piston (60) are the same. Hereinafter, the eccentric distance Le1 of the first piston (50) and the eccentric distance Le2 of the second piston (60) will not be distinguished from each other and will be referred to as the eccentric distance Le. Herein, the "eccentric distance Le1 of the first piston (50)" means the distance from the axis (AC) of the drive shaft (25) to the center (C5) of the first piston (50), and the "eccentric distance Le2 of the second piston (60)" means the distance from the axis (AC) of the drive shaft (25) to the center (C6) of the second piston (60).

[0089] The thickness Tm of the middle plate (38) is designed in relation to the diameter Ds of the first cylinder chamber (37) and the second cylinder chamber (42). Specifically, the diameter Ds of both the first cylinder chamber (37) and the second cylinder chamber (42) and the thickness Tm of the middle plate (38) satisfy the relational expression expressed by the following formula (2): 1 / 30≦Tm / Ds≦1 / 10 (2) The relational expression expressed by the above formula (2) was devised based on a calculation formula for the deflection and stress of a circular plate with a hole.

[0090] As shown in FIG. 6, when the configuration of the first cylinder chamber (37) and the first piston (50) and the configuration of the second cylinder chamber (42) and the second piston (60) are considered as a simplified model in which the first piston (50) is located at the center of the first cylinder chamber (37) and the second piston (60) is located at the center of the second cylinder chamber (42), the amount of deflection y of the middle plate (38) can be calculated from the formula for calculating the deflection and stress of the holed disk for the structural model shown in FIG. ｍａｘ is expressed by the following equation (3). Here, "k" is a coefficient that changes depending on the value of a / b. "a" is the radius of the area of ​​the middle plate (38) facing the first working space (53) or the second working space (63) (hereinafter referred to as the "outer radius of the middle plate (38)"). "b" is the radius of the portion of the area of ​​the middle plate (38) facing the first working space (53) or the second working space (63) that overlaps with the first piston (50) or the second piston (60) (hereinafter referred to as the "inner radius of the middle plate (38)"). The inner radius b of the middle plate (38) is expressed as b = a - e. "e" is the distance corresponding to the difference between the outer radius a and the inner radius b of the middle plate (38) and corresponds to the eccentric distance Le of the first piston (50) or the second piston (60). "P" is the load applied to the middle plate (38) in the thickness direction. "E" is the elastic modulus of the middle plate (38).

[0091] The outer radius a of the middle plate (38) is half the diameter Ds of the first cylinder chamber (37) and the second cylinder chamber (42), and is therefore expressed as a=Ds / 2. By modifying the above equation (3) in light of this, the following equation (4) is obtained. From the above formula (4), the deflection amount y with respect to the thickness Tm of the middle plate (38) is ｍａｘ The ratio (y ｍａｘ / Tm) is (Ds / Tm) ４ is proportional to.

[0092] The index value y, which indicates the amount of deflection of the middle plate (38) on the left side of the above formula (4), ｍａｘ The relationship between Ds / Tm and Ds / Tm appearing on the right side of the above formula (4) is shown in a graph in Fig. 8. The data in Fig. 8 was calculated assuming that the material of the middle plate (38) is cast iron (E = 110 GPa) and the differential pressure between the first cylinder chamber (37) and the second cylinder chamber (42) is 3 MPa (P = 3 MPa). As shown in Fig. 8, the index value y ｍａｘ The larger the value of Ds / Tm, the larger the value of Ds / Tm.

[0093] Furthermore, when the diameter Ds of the first cylinder chamber (37) and the second cylinder chamber (42) is 50 mm, the eccentric distance Le of the first piston (50) and the eccentric distance Le of the second piston (60) are 5 mm, and k=0.00077, as shown in Fig. 9, when the function Ds / Tm is in the range of 10 to 30, the amount of deflection of the middle plate (38) can be made sufficiently smaller than the first gap and the second gap (10 µm or less). Therefore, the diameters Ds of both the first cylinder chamber (37) and the second cylinder chamber (42) and the thickness Tm of the middle plate (38) are designed to satisfy the relationship (1 / 30≦Tm / Ds≦1 / 10) expressed by the above formula (2).

[0094] The diameter Da of the main shaft portion (26) is designed in relation to the diameter Ds of the first cylinder chamber (37) and the second cylinder chamber (42). Specifically, the diameter Ds of both the first cylinder chamber (37) and the second cylinder chamber (42) and the diameter Da of the main shaft portion (26) satisfy the relational expression expressed by the following formula (5). As a result, the diameter Da of the main shaft portion (26) in this example is designed to be relatively small compared to the diameter Ds of the first cylinder chamber (37) and the second cylinder chamber (42): Da≦Ds×0.35 (5)

[0095] The eccentric distance Le of the first piston (50) and the second piston (60) is designed in relation to the radius Rs of the first cylinder chamber (37) and the second cylinder chamber (42). Specifically, the radius Rs of both the first cylinder chamber (37) and the second cylinder chamber (42) and the eccentric distance Le of the first piston (50) and the second piston (60) satisfy the relational expression expressed by the following equation (6): Le / Rs≦0.25 (6)

[0096] As described above, the outer radius a of the middle plate (38) is expressed as a = Ds / 2, and the inner radius b of the middle plate (38) is expressed as b = a - e. Based on this, the above formula (6) can be transformed to the following formula (7): a / b≦1.333 (7) In this case, the coefficient k in the above formula (3) can be considered to be 0.00077, the same as when a / b = 1.25 in the known table showing the relationship between the coefficient k and a / b. Furthermore, the above formula (4) can be transformed to the following formula (8): Furthermore, since a / Tm=0.5×Ds / Tm, the above formula (2) can be transformed to the following formula (9): 5≦a / Tm≦15 (9)

[0097] In the above formula (8), when the data in FIG. 8 are the same as above, E = 110 GPa and P = 3 MPa, from the above formula (9), y ｍａｘ The range of / Tm is expressed by the following formula (10): 0.000013≦y ｍａｘ / Tm≦0.0001 ... (10) Therefore, by designing the ratio (Le / Rs) of the radius Rs of each of the first cylinder chamber (37) and the second cylinder chamber (42) to the eccentric distance Le of each of the first piston (50) and the second piston (60) within an appropriate range so as to satisfy the above formula (6), it is possible to suppress the deflection of the middle plate (38) to 1 / 1000 or less of the thickness Tm.

[0098] Features of the Embodiment In the rotary compressor (10) of this embodiment, the thickness Tm of the middle plate (38) is 1 / 30 to 1 / 10 of the diameter Ds of both the first cylinder chamber (37) and the second cylinder chamber (42). When the thickness Tm of the middle plate (38) is 1 / 30 or more of the diameter Ds of the first cylinder chamber (37) and the second cylinder chamber (42), bending of the middle plate (38) due to the pressure of the fluid compressed in the first cylinder chamber (37) and the second cylinder chamber (42) can be suitably suppressed. Furthermore, when the thickness Tm of the middle plate (38) is 1 / 10 or less of the diameter Ds of the first cylinder chamber (37) and the second cylinder chamber (42), the distance between the front head (31) and the rear head (43) can be shortened. This suppresses bending of the drive shaft (25). Therefore, reliability can be improved when the diameter of the drive shaft (25) of the rotary compressor (10) is reduced.

[0099] In the rotary compressor (10) of this embodiment, the distance L1 between the centers (C1, C2) of the first and second suction pipes (15) and (16) at their portions passing through the casing (11) is greater than the distance L2 between the centers (C3, C4) in the height direction of the first and second cylinder chambers (37) and (42). This ensures the strength of the portions of the casing (11) through which the first and second suction pipes (15) and (16) pass.

[0100] In the rotary compressor (10) of this embodiment, the ratio (Le / Rs) of the eccentric distance Le of the first piston (50) to the radius Rs of the first cylinder chamber (37) and the ratio (Le / Rs) of the eccentric distance Le of the second piston (60) to the radius Rs of the second cylinder chamber (42) are each 0.25 or less. Therefore, based on a calculation formula for the deflection and stress of a perforated disk, the amount of deflection of the middle plate (38) can be suitably suppressed and made small relative to the thickness of the middle plate (38). This is advantageous for improving the reliability of the rotary compressor (10).

[0101] In the rotary compressor (10) of this embodiment, the first suction pipe (15) is connected to the first cylinder (35), and the second suction pipe (16) is connected to the rear head (43). This makes it possible to specifically realize a configuration in which the distance L1 between the centers (C1, C2) of the first suction pipe (15) and the second suction pipe (16) at their portions penetrating the casing (11) is greater than the distance L2 between the centers (C3, C4) of the first cylinder chamber (37) and the second cylinder chamber (42) in the height direction. Furthermore, since the first suction pipe (15) is connected to the first cylinder (35), the flow path of the refrigerant sent to the compression mechanism (30) through the first suction pipe (15) to the first cylinder chamber (37) is shortened compared to when the first suction pipe (15) is connected to the front head (31), thereby reducing the pressure loss of the refrigerant.

[0102] In the rotary compressor (10) of this embodiment, the diameter Da of the main shaft portion (26) of the drive shaft (25) supported by the front head (31) is 0.35 times or less the diameter Ds of the first cylinder chamber (37) or the second cylinder chamber (42). Such a relatively small diameter Da of the main shaft portion (26) can reduce friction loss between the main shaft portion (26) and the front head (31). This can improve the compression efficiency of the rotary compressor (10). On the other hand, a drive shaft (25) having a relatively small diameter main shaft portion (26) is prone to bending during operation of the rotary compressor (10). The technology of the present disclosure is particularly effective for a rotary compressor (10) including such a drive shaft (25) because it can suppress bending of the drive shaft (25).

[0103] In the rotary compressor (10) of this embodiment, a first annular groove (34) is formed in the end surface of the front head (31) facing the middle plate (38). This allows the first bearing portion (32) of the front head (31) to be elastically deformable between the first annular groove (34) and the first bearing hole (33). Furthermore, a second annular groove (46) is formed in the end surface of the rear head (43) facing the middle plate (38). This allows the second bearing portion (44) of the rear head (43) to be elastically deformable between the second annular groove (46) and the second bearing hole (45).

[0104] During operation of the rotary compressor (10), the pressure of the refrigerant compressed in the first cylinder chamber (37) acts on the first piston (50), and the pressure of the refrigerant compressed in the second cylinder chamber (42) acts on the second piston (60), resulting in a compression load being applied to the drive shaft (25), causing the drive shaft (25) to bend in the radial direction. When the drive shaft (25) bends, the first bearing (32) and the second bearing (44) elastically deform toward the first annular groove (34) or the second annular groove (46) depending on the bending of the drive shaft (25), and bend together with the drive shaft (25). This prevents the drive shaft (25) from strongly contacting the front head (31) or the rear head (43), thereby reducing wear between the first bearing (32) and the second bearing (44) and the drive shaft (25).

[0105] In the rotary compressor (10) of this embodiment, the maximum rotation speed of the drive shaft (25) is relatively high, at 120 rps or more. The higher the rotation speed of the drive shaft (25), the greater the tendency for the drive shaft (25) to bend. The technique of the present disclosure is particularly effective in a rotary compressor (10) operated at such a relatively high rotation speed, since it can suppress bending of the drive shaft (25).

[0106] The refrigeration system (1) of this embodiment includes a rotary compressor (10). The reliability of the rotary compressor (10) is improved when the diameter of the drive shaft (25) of the rotary compressor (10) is reduced. By including the rotary compressor (10), the compression efficiency is increased by reducing the diameter of the drive shaft (25), thereby improving the energy efficiency of the refrigeration system (1) while maintaining its reliability.

[0107] -First Modification- In the rotary compressor (10) of the first modification, the main shaft portion (26) and the counter shaft portion (29) of the drive shaft (25) are designed to have different diameters Da and Db, as shown in Fig. 10. Specifically, in the drive shaft (25), the diameter Da of the main shaft portion (26) and the diameter Db of the counter shaft portion (29) satisfy the relational expression expressed by the following equation (11): Db<Da (11)

[0108] In the rotary compressor (10) of the first modified example, the diameter Db of the countershaft (29) of the drive shaft (25), which is supported by the rear head (43), is smaller than the diameter Da of the main shaft (26) which is supported by the front head (31). When the diameter Db of the countershaft (29) is smaller than the diameter Da of the main shaft (26), friction loss between the countershaft (29) and the rear head (43) can be reduced compared to when the diameter Db of the countershaft (29) is the same as the diameter Da of the main shaft (26). This is advantageous for increasing the compression efficiency of the rotary compressor (10).

[0109] -Second Modification- In a rotary compressor (10) of this second modification, as shown in Fig. 11, the connection portions of the first suction pipe (15) and the second suction pipe (16) differ from those of the above embodiment. Specifically, the first suction pipe (15) is connected to the front head (31), and the second suction pipe (16) is connected to the second cylinder (40). In this example, the first suction passage (54) is formed by a cylinder-side passage (65) and a head-side passage (66) similar to the second suction passage (64) of the above embodiment. Furthermore, the second suction passage (64) is formed in the same manner as the first suction passage (54) of the above embodiment.

[0110] -Third Modification- In a rotary compressor (10) of this third modification, as shown in Fig. 12, the connection portion of the first suction pipe (15) differs from that of the above embodiment. Specifically, the first suction pipe (15) is connected to the front head (31), and the second suction pipe (16) is connected to the rear head (43). In this example, the first suction pipe (15) is formed of a cylinder-side passage (65) and a head-side passage (66) similar to the second suction passage (64) of the above embodiment. The second suction pipe (16) is also formed of a cylinder-side passage (65) and a head-side passage (66) similar to those of the above embodiment.

[0111] Other Embodiments As shown in Fig. 13 , the compression mechanism (30) of the rotary compressor (10) of the above-described embodiment may be configured as a rolling piston type in which the first blade (52) of the first piston (50) is formed separately from the first roller (51). In this compression mechanism (30), the flat first blade (52) is fitted in a first blade groove (90) extending radially of the first cylinder (35) so as to be movable forward and backward, and the first bushing (49) is omitted. The first blade (52) is pressed against the outer circumferential surface of the first roller (51) by a spring (91). The tip of the first blade (52) is in contact with the outer circumferential surface of the first roller (51) so as to be able to slide and move. These features may also be applied to the second piston (60).

[0112] The diameter Ds1 of the first cylinder chamber (37) and the diameter Ds2 of the second cylinder chamber (42) may be different from each other. In this case, the smaller of the diameter Ds1 of the first cylinder chamber (37) and the diameter Ds2 of the second cylinder chamber (42) is defined as the diameter Ds, and the diameter Ds satisfies the relationship (1 / 30≦Tm / Ds≦1 / 10) expressed by the above formula (2). In short, it is sufficient that the diameters Ds (Ds1, Ds2) of both the first cylinder chamber (37) and the second cylinder chamber (42) or the smaller diameter Ds, and the thickness Tm of the middle plate (38) satisfy the relationship expressed by the above formula (2).

[0113] The first annular groove (34) may not be formed in the lower surface of the front head (31). Also, the second annular groove (46) may not be formed in the upper surface of the rear head (43). That is, the first annular groove (34) or the second annular groove (46) may be formed in the end surface of one of the front head (31) and the rear head (43) on the side of the middle plate (38), and only one of the first bearing portion (32) and the second bearing portion (44) may be configured to be partially elastically deformable.

[0114] The compression mechanism (30) may be configured as a two-stage compression type in which refrigerant compressed in one of the first cylinder chamber (37) and the second cylinder chamber (42) is further compressed in the other. The compression mechanism (30) may also be configured to include three or more cylinders. For example, the compression mechanism (30) may have a stacked structure including a front head (31), a first cylinder (35), a first middle plate corresponding to the middle plate (38), a second cylinder (40), a second middle plate, a third cylinder, and a rear head (43).

[0115] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments and modifications may be combined or substituted as appropriate as long as the functionality of the subject matter of the present disclosure is not impaired.

[0116] INDUSTRIAL APPLICABILITY As described above, the present disclosure is useful for rotary compressors and refrigeration devices.

[0117] 1 Refrigeration unit 10 Rotary compressor 11 Casing 15 First suction pipe 16 Second suction pipe 21 Electric motor 25 Drive shaft 26 Main shaft 29 Sub-shaft 31 Front head (First head) 33 First bearing hole (Bearing hole) 34 First annular groove (Annular groove) 35 First cylinder 37 First cylinder chamber 38 Middle plate 40 Second cylinder 42 Second cylinder chamber 43 Rear head (Second head) 45 Second bearing hole (Bearing hole) 46 Second annular groove (Annular groove) 50 First piston 60 Second piston AC Shaft center

Claims

1. A compression mechanism (30) having a structure in which a first head (31), a first cylinder (35), a middle plate (38), a second cylinder (40), and a second head (43) are stacked; and a drive shaft (25) provided to penetrate the compression mechanism (30) in the stacking direction and rotatably supported by the first head (31) and the second head (43), wherein a first cylinder chamber (37) defined by the first head (31) and the middle plate (38) is formed inside the first cylinder (35), and a first piston (50) is accommodated in the first cylinder chamber (37) that compresses a fluid sucked into the first cylinder chamber (37) by eccentrically rotating in accordance with the rotation of the drive shaft (25), and a second cylinder chamber (42) defined by the middle plate (38) and the second head (43) is formed inside the second cylinder (40), a second piston (60) is accommodated in the second cylinder chamber (42), the second piston (60) rotating eccentrically in association with the rotation of the drive shaft (25) to compress a fluid sucked into the second cylinder chamber (42), and a diameter Ds of both the first cylinder chamber (37) and the second cylinder chamber (42), or a smaller diameter Ds, and a thickness Tm of the middle plate (38) satisfy a relational expression expressed as 1 / 30≦Tm / Ds≦1 / 10.

2. A rotary compressor according to claim 1, further comprising: a casing (11) accommodating the compression mechanism (30) and the drive shaft (25); a first suction pipe (15) for drawing fluid into the first cylinder chamber (37); and a second suction pipe (16) for drawing fluid into the second cylinder chamber (42), wherein the first suction pipe (15) and the second suction pipe (16) each penetrate through the casing (11), and a distance L1 between a center (C1) of the portion of the first suction pipe (15) that penetrates through the casing (11) and a center (C2) of the portion of the second suction pipe (16) that penetrates through the casing (11), and a distance L2 between a center (C3) in the height direction of the first cylinder chamber (37) and a center (C4) in the height direction of the second cylinder chamber (42) satisfy the relational expression L1>L2.

3. A rotary compressor according to claim 1 or 2, wherein the first piston (50) and the second piston (60) are eccentric with respect to the axis (AC) of the drive shaft (25), and an eccentric distance Le of the first piston (50) or the second piston (60) related to the diameter Ds that satisfies the relational expression, and a radius Rs of the first cylinder chamber (37) formed inside the first piston (50) or a radius Rs of the second cylinder chamber (42) formed inside the second piston (60) satisfy a relational expression expressed by Le / Rs≦0.

25.

4. The rotary compressor according to any one of claims 1 to 3, wherein the first suction pipe (15) is connected to the first head (31), or the second suction pipe (16) is connected to the second head (43).

5. A rotary compressor according to any one of claims 1 to 3, wherein the first suction pipe (15) is connected to the first head (31) and the second suction pipe (16) is connected to the second cylinder (40), or the first suction pipe (15) is connected to the first cylinder (35) and the second suction pipe (16) is connected to the second head (43).

6. A rotary compressor according to any one of claims 1 to 5, further comprising an electric motor (21) connected to the drive shaft (25), wherein the electric motor (21) is positioned between the electric motor (21) and the first cylinder (35) via the first head (31), the drive shaft (25) has a main shaft portion (26) supported by the first head (31), and the diameter Ds that satisfies the relational expression and the diameter Da of the main shaft portion (26) satisfy the relational expression expressed as Da≦Ds×0.

35.

7. A rotary compressor according to any one of claims 1 to 6, further comprising an electric motor (21) connected to the drive shaft (25), wherein the electric motor (21) is disposed at a position between the electric motor (21) and the first cylinder (35) with the first head (31) interposed therebetween, the drive shaft (25) having a main shaft portion (26) supported by the first head (31) and a counter shaft portion (29) supported by the second head (43), wherein a diameter Da of the main shaft portion (26) and a diameter Db of the counter shaft portion (29) satisfy the relational expression Db<Da.

8. A rotary compressor according to any one of claims 1 to 7, wherein a bearing hole (33, 45) through which the drive shaft (25) is inserted is formed in the first head (31) and the second head (43), and an annular groove (34, 46) extending along the periphery of the bearing hole (33, 45) is formed in the end face of the first head (31) or the second head (43) on the side of the middle plate (38).

9. The rotary compressor according to any one of claims 1 to 8, wherein the maximum rotation speed of the drive shaft (25) is 120 rps or more.

10. A refrigeration system comprising a rotary compressor (10) according to any one of claims 1 to 9.

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