EP4707601A1

EP4707601A1 - Rotary compressor and refrigeration device

Info

Publication number: EP4707601A1
Application number: EP25792759.0A
Authority: EP
Inventors: Takazo Sotojima; Arisa KAWAE; Hiromichi Ueno; Tatsuya KATAYAMA; Tomoya KUMAZAKI; Hikaru Wada
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2024-07-18
Filing date: 2025-05-08
Publication date: 2026-03-11
Also published as: WO2026018530A1; JP2026013916A

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 the middle plate and a rear head (43) is formed inside a second cylinder (40). A first piston (50) and a second piston (60) are housed 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 a relational expression expressed as 1/30 ≤ Tm/Ds ≤ 1/10.

Description

TECHNICAL FIELD

The present disclosure relates to a rotary compressor and a refrigeration apparatus.

BACKGROUND ART

Two-cylinder rotary compressors have been known as rotary compressors. The two-cylinder rotary compressors are configured such that an inner rotor type motor, a drive shaft coupled to the motor, and a compression mechanism driven by rotation of the drive shaft are housed inside a cylindrical closed container, and that the axial direction along the axis of the drive shaft is the vertical direction of the rotary compressor. The compression mechanism is of a two-cylinder type, and includes a first head, a first cylinder, a middle plate, a second cylinder, and a second head.
The first cylinder forms a first cylinder chamber, and the second cylinder forms 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 cylinder and the second cylinder to partition the first cylinder chamber and the second cylinder chamber. The second head is provided on the lower surface of the second cylinder and defines the second cylinder chamber.
The first cylinder chamber houses a first roller, and the second cylinder chamber houses a second roller. A crankshaft has a first eccentric portion fitted to the first roller and a second eccentric portion fitted to the second roller, and is supported by the first head and the second head. In the compression mechanism, the first roller is eccentrically rotated in the first cylinder chamber and the second roller is eccentrically rotated in the second cylinder chamber as the crankshaft rotates. As a result, fluid is sucked into the first cylinder chamber and the second cylinder chamber and is then compressed.
An example of such a two-cylinder rotary compressor is disclosed in Patent Document 1.

CITATION LIST

PATENT DOCUMENTS

Patent Document 1: Japanese Unexamined Patent Publication No. 2014-196714

SUMMARY OF THE INVENTION

TECHNICAL PROBLEM

In the rotary compressor such as one described above, there has been a demand for reducing the diameter of the drive shaft to increase a compression efficiency, and for improvement in the reliability, reducing the deflection of the drive shaft by reducing a distance between the first head and the second head which are the points of support for the drive shaft. Thus, it is conceivable to reduce the thickness of the middle plate. However, if the middle plate is made too thin, the strength of the middle plate is reduced, and the middle plate may be deflected and deformed by the pressure of the fluid compressed in the first cylinder chamber and the second cylinder chamber. If this happens, the middle plate comes into contact with the first roller, the second roller, or other components, and the reliability of the rotary compressor is lowered.
It is an object of the present disclosure to improve the reliability of a rotary compressor when the diameter of a drive shaft is reduced.

SOLUTION TO THE PROBLEM

A first aspect of the present disclosure is directed to a rotary compressor (10). The rotary compressor (10) of the first aspect includes 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 on one another; and a drive shaft (25) provided so as to penetrate the compression mechanism (30) in a stacking direction and rotatably supported by the first head (31) and the second head (43). Inside the first cylinder (35), a first cylinder chamber (37) defined by the first head (31) and the middle plate (38) is formed. The first cylinder chamber (37) houses a first piston (50) configured to rotate eccentrically along with rotation of the drive shaft (25) and thereby compress a fluid sucked into the first cylinder chamber (37). Inside the second cylinder (40), a second cylinder chamber (42) defined by the middle plate (38) and the second head (43) is formed. The second cylinder chamber (42) houses a second piston (60) configured to rotate eccentrically along with rotation of the drive shaft (25) and thereby compress a fluid sucked into the second cylinder chamber (42). Diameters Ds of both the first cylinder chamber (37) and the second cylinder chamber (42) or a smaller one of the diameters Ds and a thickness Tm of the middle plate (38) satisfy a relational expression expressed as 1/30 ≤ Tm/Ds ≤ 1/10.
According to the first aspect, the thickness Tm of the middle plate (38) is 1/30 to 1/10 of the diameters Ds of both the first cylinder chamber (37) and the second cylinder chamber (42) or the smaller one of the diameters DS. When the thickness Tm of the middle plate (38) is 1/30 or more of the diameter Ds of a predetermined cylinder chamber (the first cylinder chamber (37) or the second cylinder chamber (42)), the deflection of the middle plate (38) in response to the pressure of the fluid compressed in the cylinder chamber can be suitably reduced. Further, when the thickness Tm of the middle plate (38) is 1/10 or less of the diameter Ds of the cylinder chamber, the distance between the first head (31) and the second head (43) can be reduced. This can reduce deflection of the drive shaft (25). Thus, the reliability of the rotary compressor (10) with a reduced diameter of the drive shaft (25) can be improved.
A second aspect of the present disclosure is the rotary compressor (10) of the first aspect, further including: a casing (11) configured to house the compression mechanism (30) and the drive shaft (25); a first suction pipe (15) configured to suck a fluid into the first cylinder chamber (37); and a second suction pipe (16) configured to suck a fluid into the second cylinder chamber (42). Each of the first suction pipe (15) and the second suction pipe (16) penetrates the casing (11). A distance L1 between a center (C1) of a portion of the first suction pipe (15) penetrating the casing (11) and a center (C2) of a portion of the second suction pipe (16) penetrating the casing (11), and a distance L2 between a center (C3) of the first cylinder chamber (37) in a height direction and a center (C4) of the second cylinder chamber (42) in a height direction satisfy a relational expression expressed as L1 > L2.
According to the second aspect, the distance L1 between the centers (C1, C2) of the portions of the first suction pipe (15) and the second suction pipe (16) penetrating the casing (11) is larger 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. This configuration can ensure the strength of the portions of the casing (11) where the first suction pipe (15) and the second suction pipe (16) penetrate.
A third aspect of the present disclosure is the rotary compressor (10) of the first or second aspect. In the third aspect, the first piston (50) and the second piston (60) are eccentric with respect to an axis (AC) of the drive shaft (25). An eccentric distance Le of the first piston (50) or the second piston (60) 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) relate to the diameter Ds satisfying the relational expression of the first aspect and satisfy a relational expression expressed as Le/Rs ≤ 0.25.
According to the third aspect, the ratio (Le/Rs) between the eccentric distance Le of the first piston (50) and the radius Rs of the first cylinder chamber (37) or the ratio (Le/Rs) between the eccentric distance Le of the second piston (60) and the radius Rs of the second cylinder chamber (42) based on the diameter Ds satisfying the relational expression of the first aspect is 0.25 or less. Thus, based on a calculation expression relating to deflection and stress of a circular plate with a hole, the deflection amount of the middle plate (38) can be suitably reduced and can be extremely small with respect to the thickness of the middle plate (38). This is advantageous in improving the reliability of the rotary compressor (10).
A fourth aspect of the present disclosure is the rotary compressor (10) of any one of the first to third aspects. 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).
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 the configuration in which the distance between both the centers (C1, C2) of the portions of the first suction pipe (15) and the second suction pipe (16) penetrating the casing (11) is larger than the distance between both the centers (C1, C2) of the first cylinder chamber (37) and the second cylinder chamber (42) in the height direction.
A fifth aspect of the present disclosure is the rotary compressor (10) of any one of the first to third aspects. 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).
According to 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 makes it possible to achieve the specific configuration in which the distance between the centers (C1, C2) of the portions of the first suction pipe (15) and the second suction pipe (16) penetrating 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. Moreover, 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 through which the fluid flowing toward the compression mechanism (30) via the first suction pipe (15) or the second suction pipe (16) reaches the first cylinder chamber (37) or the second cylinder chamber (42) can be shortened, thereby reducing a fluid pressure loss, as compared with a case where 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).
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 at which the first head (31) is interposed between the electric motor (21) and the first cylinder (35). The drive shaft (25) has a main shaft portion (26) supported by the first head (31). The diameter Ds satisfying the relational expression of the first aspect and a diameter Da of the main shaft portion (26) satisfy a relational expression expressed as Da ≤ Ds × 0.35.
According to 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 of the diameter Ds, satisfying the relational expression of the first aspect, of the first cylinder chamber (37) or the second cylinder chamber (42). When the diameter Da of the main shaft portion (26) is relatively small as described above, a friction loss between the main shaft portion (26) and the first head (31) can be reduced. This can increase the compression efficiency of the rotary compressor (10). On the other hand, the drive shaft (25) having the main shaft portion (26) with a relatively small diameter is likely to deflect during operation of the rotary compressor (10). In the rotary compressor (10) including such a drive shaft (25), the technique of the present disclosure is particularly effective as it can reduce the deflection of the drive shaft (25).
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 at which the first head (31) is interposed between the electric motor (21) and the first cylinder (35). The drive shaft (25) has a main shaft portion (26) supported by the first head (31) and an auxiliary shaft portion (29) supported by the second head (43). A diameter Db of the auxiliary shaft portion (29) and a diameter Da of the main shaft portion (26) satisfy a relational expression expressed as Db < Da.
According to the seventh aspect, the diameter Db of the auxiliary shaft portion (29) of the drive shaft (25) supported by the second head (43) is smaller than the diameter Da of the main shaft portion (26) supported by the first head (31). When the diameter Db of the auxiliary shaft portion (29) is smaller than the diameter Da of the main shaft portion (26), the friction loss between the auxiliary shaft portion (29) and the second head (43) can be reduced as compared with a case where the diameter Db of the auxiliary shaft portion (29) and the diameter Da of the main shaft portion (26) are the same. This is advantageous in increasing the compression efficiency of the rotary compressor (10).
An eighth aspect of the present disclosure is the rotary compressor (10) of any one of the first to seventh aspects. In the eighth aspect, The first head (31) and the second head (43) have bearing holes (33, 45) through which the drive shaft (25) is inserted. An annular groove (34, 46) extending along a periphery of the bearing hole (33, 45) is formed in an end face of the first head (31) or the second head (43) facing the middle plate (38).
According to the eighth aspect, the annular groove (34, 46) is formed in the end face of the first head (31) or the second head (43) facing the middle plate (38). According to this configuration, an elastically deformable bearing portion (32, 44) can be formed between the annular groove (34, 46) and a 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). The resultant compression load is applied to the drive shaft (25), causing deflection of the drive shaft (25) in the radial direction. When the drive shaft (25) deflects, the bearing portion (32, 44) is elastically deformed to the annular groove (34, 46) side in response to the deflection of the drive shaft (25), and deflects together with the drive shaft (25). This makes it possible to prevent the drive shaft (25) from coming into strong and partial contact with the bearing portion (32, 44) of the first head (31) or the second head (43), thereby reducing wear between the drive shaft (25) and the bearing portion (32, 44).
A ninth aspect of the present disclosure is the rotary compressor (10) of any one of the first to eighth aspects. In the ninth aspect, a maximum number of rotations of the drive shaft (25) is 120 rps or more.
According to the ninth aspect, the maximum number of rotations of the drive shaft (25) is 120 rps or more, which is relatively high. As the rotational speed of the drive shaft (25) increases, the deflection of the drive shaft (25) tends to become larger. In the rotary compressor (10) operated with a relatively great number of rotations as described above, the technique of the present disclosure is particularly effective as it can reduce the deflection of the drive shaft (25).
A tenth aspect of the present disclosure is directed to a refrigeration apparatus (1). The refrigeration apparatus (1) of the tenth aspect includes the rotary compressor (10) of any one of the first to ninth aspects.
The tenth aspect includes the rotary compressor (10) according to the technique of the present disclosure. In the rotary compressor (10), the reliability of the rotary compressor (10) with a reduced diameter of the drive shaft (25) can be improved. With this rotary compressor (10), the refrigeration apparatus (1) can improve energy efficiency while maintaining reliability, owing to the higher compression efficiency achieved by reducing the diameter of the drive shaft (25).

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] FIG. 1 is a refrigerant circuit diagram illustrating, as an example, a configuration of a refrigeration apparatus of an embodiment.
[FIG. 2] FIG. 2 is a longitudinal sectional view illustrating, as an example, a configuration of a rotary compressor.
[FIG. 3] FIG. 3 is a longitudinal sectional view illustrating, as an example, a main portion of the rotary compressor.
[FIG. 4] FIG. 4 is a transverse sectional view illustrating, as an example, configurations of a first cylinder and a first piston.
[FIG. 5] FIG. 5 is a transverse sectional view illustrating, as an example, configurations of a second cylinder and a second piston.
[FIG. 6] FIG. 6 is a schematic view illustrating a simplified model of the configurations of a first cylinder chamber and the first piston and the configurations of a second cylinder chamber and the second piston.
[FIG. 7] FIG. 7 is a schematic view illustrating a structural model for a calculation expression relating to the deflection and stress of a circular plate with a hole.
[FIG. 8] FIG. 8 is a graph showing a relationship between the ratio (Ds/Tm) of the diameter of the first cylinder chamber or the second cylinder chamber to the thickness of a middle plate and an index value (y_max/t) indicating the deflection amount of the middle plate.
[FIG. 9] FIG. 9 is a graph showing, as an example, a 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 deflection amount of the middle plate.
[FIG. 10] FIG. 10 is a longitudinal sectional view illustrating, as an example, a main portion of a rotary compressor of a first variation.
[FIG. 11] FIG. 11 is a longitudinal sectional view illustrating, as an example, a main portion of a rotary compressor of a second variation.
[FIG. 12] FIG. 12 is a longitudinal sectional view illustrating, as an example, a main portion of a rotary compressor of a third variation.
[FIG. 13] FIG. 13 is a transverse sectional view illustrating, as an example, configurations of a first cylinder and a first piston of another embodiment.

DESCRIPTION OF EMBODIMENTS

Exemplary embodiments will be described in detail below with reference to the drawings. In the following embodiment, a case in which a rotary compressor according to the present disclosure is applied to a refrigeration apparatus will be described as an example. The drawings are used for conceptual description of the present disclosure. In the drawings, dimensions, ratios, or numbers may be exaggerated or simplified for easy understanding of the present disclosure.
In the following embodiment, a direction along the axis of a drive shaft of the rotary compressor will be referred to as an "axial direction," a direction perpendicular to the axial direction as a "radial direction," and a direction along the circumference of the drive shaft as a "circumferential direction." In addition, the expressions of "first," "second," . . . are used to distinguish the terms to which these expressions are given, and do not limit the number and order of the terms.

<<Embodiment>>

As illustrated in FIG. 1, a rotary compressor (10) of this embodiment is provided in a refrigeration apparatus (1).

-Refrigeration Apparatus-

The refrigeration apparatus (1) includes a refrigerant circuit (1a). The refrigerant circuit (1a) is filled with refrigerant. The refrigerant is an example of fluid compressed by the rotary compressor (10). The refrigerant circuit (1a) has the rotary compressor (10), a radiator (3), a decompression mechanism (4), and an evaporator (5). The decompression mechanism (4) is an expansion valve, for example. The refrigerant circuit (1a) performs a vapor compression refrigeration cycle.
In the refrigeration cycle, the rotary compressor (10) sucks and compresses low-pressure gas refrigerant, and discharges high-pressure gas refrigerant. The high-pressure gas refrigerant compressed by the rotary compressor (10) dissipates heat to air in the radiator (3). At this time, the refrigerant is liquefied and changed into liquid refrigerant. The liquid refrigerant having dissipated heat is decompressed by the decompression mechanism (4). The decompressed liquid refrigerant is evaporated in the evaporator (5). At this time, the refrigerant is vaporized and changed into low-pressure gas refrigerant. The low-pressure gas refrigerant generated in the evaporator (5) is sucked into the rotary compressor (10).
The refrigeration apparatus (1) is an air conditioner. The air conditioner may be a cooling and heating machine that switches between cooling and heating. In this case, the air conditioner has a switching mechanism that switches the direction of circulation of the refrigerant. The switching mechanism is a four-way switching valve, for example. The air conditioner may be a machine dedicated to cooling or a machine dedicated to heating. The refrigeration apparatus (1) may be a water heater, a chiller unit, or a cooling apparatus configured to cool air in an internal space. The cooling apparatus is for cooling the air inside a water heater, a refrigerator, a freezer, or a container, for example.

-Rotary Compressor-

As illustrated in FIG. 2, the rotary compressor (10) is a two-cylinder rotary compressor. The maximum number of rotations of the rotary compressor (10) is 120 rps or more. The "maximum number of rotations" described herein is the number of rotations of a drive shaft (25) rotated by the operation of an electric motor (21), and refers to the highest possible number of rotations in the product operation range. It is preferable to increase the maximum number of rotations of the rotary compressor (10) in order to increase the amount of circulation of the refrigerant in the refrigerant circuit (1a) and ensure the maximum amount of circulation of the refrigerant.
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 in the casing (11).

The casing (11) is configured as a vertically-long cylindrical closed container with both ends closed. The casing (11) is positioned upright. The casing (11) has a barrel (12), a lower end plate (13), and an upper end plate (14). The barrel (12) is in the shape of a cylinder extending in the up-and-down direction. The lower end plate (13) is fixed to the lower end of the barrel (12) to close the lower end opening of the barrel (12). The upper end plate (14) is fixed to the upper end of the barrel (12) to close the upper end opening of the barrel (12).
A first suction pipe (15) and a second suction pipe (16) are fixed to the barrel (12). Each of the first suction pipe (15) and the second suction pipe (16) penetrates the barrel (12), and is connected to the compression mechanism (30). The first suction pipe (15) of this embodiment is connected to a first cylinder (35), and the second suction pipe (16) is connected to a rear head (43). A discharge pipe (17) is fixed to the upper end plate (14). The discharge pipe (17) penetrates the upper end plate (14), and is open to an upper space in the casing (11).
The casing (11) has, at its bottom, an oil reservoir (18). The oil reservoir (18) is formed by inner walls of a lower portion of the barrel (12) and the lower end plate (13). The oil reservoir (18) stores oil. This oil lubricates sliding portions of the compression mechanism (30) and the drive shaft (25).

The drive mechanism (20) has the electric motor (21) and the drive shaft (25). The electric motor (21) is disposed above the compression mechanism (30). The electric motor (21) is provided at a position at which a front head (31) is interposed between the electric motor (21) and the first cylinder (35). The electric motor (21) has a stator (22) and a rotor (23). Each of the stator (22) and the rotor (23) has a cylindrical shape. The stator (22) is fixed to the inner peripheral surface of the barrel (12) of the casing (11). The rotor (23) is disposed in the hollow of the stator (22).
The drive shaft (25) is inserted into the hollow of the rotor (23). The rotor (23) is fixed to the drive shaft (25). The drive shaft (25) rotates together with the rotor (23) when the electric motor (21) is energized. The drive shaft (25) is a shaft member for driving the compression mechanism (30). The drive shaft (25) is disposed on the axis of the barrel (12) of the casing (11), and extends in the up-and-down direction in the casing (11). The drive shaft (25) has a main shaft portion (26), a first eccentric portion (27), a second eccentric portion (28), and an auxiliary shaft portion (29).
An upper portion of the main shaft portion (26) is fixed to the rotor (23). The first eccentric portion (27) and the second eccentric portion (28) are both provided below the main shaft portion (26). The first eccentric portion (27) is disposed above the second eccentric portion (28). The diameters of the first eccentric portion (27) and the second eccentric portion (28) are greater than the diameter of the main shaft portion (26). The first eccentric portion (27) and the second eccentric portion (28) are eccentric from the axis (AC) of the main shaft portion (26) by a predetermined distance. The first eccentric portion (27) and the second eccentric portion (28) are eccentric from the axis (AC) of the drive shaft (25) to the opposite sides.
The drive shaft (25) is provided so as to penetrate the compression mechanism (30). Part of the main shaft portion (26) above the first eccentric portion (27) is rotatably supported by the front head (31) included in the compression mechanism (30). The auxiliary shaft portion (29) forms part of the drive shaft (25) below the second eccentric portion (28), and is rotatably supported by the rear head (43) included in the compression mechanism (30). The diameter Db of the auxiliary shaft portion (29) of this example is approximately equal to the diameter Da of the main shaft portion (26) (Da = Db or Da ≈ Db) (see FIG. 3).
An oil passage (25a) is formed in the drive shaft (25). The oil passage (25a) extends to the sliding portions of the compression mechanism (30) and the drive shaft (25). An oil supply pump (25b) is provided at the lower end of the drive shaft (25) (auxiliary shaft portion (29). The oil supply pump (25b) is immersed in the oil in the oil reservoir (18), and delivers the oil as the drive shaft (25) rotates. The delivered oil is supplied to the sliding portions of the compression mechanism (30) and the drive shaft (25) through the oil passage (25a).

The compression mechanism (30) is a mechanism for sucking and compressing the refrigerant, and is disposed below the electric motor (21). The compression mechanism (30) includes the front head (31), the first cylinder (35), a middle plate (38), a second cylinder (40), and the 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.
As illustrated in FIG. 3, the compression mechanism (30) has a structure in which the front head (31), the first cylinder (35), the middle plate (38), the second cylinder (40), and the rear head (43) are stacked on one another. The front head (31), the first cylinder (35), the middle plate (38), the second cylinder (40), and the rear head (43) are stacked in this order from top to bottom and fixed with a bolt (70).
Specifically, the front head (31) has a screw hole (71). A through hole (72) is formed at a position corresponding to the screw hole (71) in each of the first cylinder (35), the middle plate (38), the second cylinder (40), and the rear head (43). The bolt (70) is inserted into the holes from the rear head (43) side, and fastens the front head (31), the first cylinder (35), the middle plate (38), the second cylinder (40), and the rear head (43) to one another.
The front head (31) is an end closure member serving as an upper lid of the first cylinder (35). The front head (31) is fixed to the barrel (12) of the casing (11). The front head (31) is stacked on top of the first cylinder (35). The front head (31) is disposed so as to cover the hollow of the first cylinder (35) from above. The front head (31) forms the upper surface of a first cylinder chamber (37).
A first bearing portion (32) is provided at a center portion of the front head (31). The first bearing portion (32) has a tubular shape, and protrudes upward. The first bearing portion (32) forms a sliding bearing. The first bearing portion (32) has a first bearing hole (33). The first bearing hole (33) is a circular hole penetrating the front head (31). The main shaft portion (26) of the drive shaft (25) is inserted in the first bearing hole (33).
A first annular groove (34) is formed in the end face of the front head (31) facing the middle plate (38), which is the lower surface in this example. The first annular groove (34) extends in an annular shape 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 elastically deformable. The front head (31) rotatably supports the main shaft portion (26) of the drive shaft (25) by the first bearing portion (32).
The first cylinder (35) is a thick substantially annular member. The first cylinder (35) has a first cylinder hole (36) in a center portion. The first cylinder hole (36) is a circular hole penetrating the first cylinder (35) in the thickness direction. The first cylinder (35) is provided in a posture in which the centerline of the first cylinder hole (36) is directed in the axial direction (up-and-down direction). The openings of the first cylinder hole (36) at both its ends are closed with the front head (31) and the middle plate (38).
The first cylinder chamber (37) is formed inside the first cylinder (35). The first cylinder chamber (37) is a space formed by the first cylinder hole (36) and surrounded by the inner peripheral 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 peripheral boundary of the first cylinder chamber (37) is defined by the inner peripheral surface of the first cylinder (35). Both boundaries of the first cylinder chamber (37) in the axial direction are defined by the lower surface of the front head (31) and the upper surface of the middle plate (38).
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 a center portion of the middle plate (38). The shaft through hole (39) is a circular hole penetrating 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 in the shaft through hole (39).
The middle plate (38) is disposed so as to cover the hollow (first cylinder hole (36)) of the first cylinder (35) from below. The middle plate (38) is disposed so as to cover the hollow (second cylinder hole (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 a second cylinder chamber (42).
The second cylinder (40) is a thick substantially annular member. The second cylinder (40) has the second cylinder hole (41) in a center portion. The second cylinder hole (41) is a circular hole penetrating the second cylinder (40) in the thickness direction. The second cylinder (40) is provided in a posture in which the centerline of the second cylinder hole (41) is directed in the axial direction (up-and-down direction). The openings of the second cylinder hole (41) at both its ends are closed with the middle plate (38) and the rear head (43).
The second cylinder chamber (42) is formed inside the second cylinder (40). The second cylinder chamber (42) is a space formed by the second cylinder hole (41) and surrounded by the inner peripheral 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 peripheral boundary of the second cylinder chamber (42) is defined by the inner peripheral surface of the second cylinder (40). Both boundaries of the second cylinder chamber (42) in the axial direction are defined by the lower surface of the middle plate (38) and the upper surface of the rear head (43).
The rear head (43) is an end closure member serving as a lower lid of the second cylinder (40). The rear head (43) is stacked on the bottom of the second cylinder (40). The rear head (43) is disposed so as to cover the hollow (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).
A second bearing portion (44) is provided at a center portion of the rear head (43). The second bearing portion (44) has a tubular shape, and protrudes downward. The second bearing portion (44) forms a sliding bearing. The second bearing portion (44) has a second bearing hole (45). The second bearing hole (45) is a circular hole penetrating the rear head (43). The auxiliary shaft portion (29) of the drive shaft (25) is inserted in the second bearing hole (45).
A second annular groove (46) is formed in the end face of the rear head (43) facing the middle plate (38), which is the upper surface in this example. The second annular groove (46) extends in an annular shape along the periphery of the second bearing hole (45). A portion of the second bearing portion (44) between the second annular groove (46) and the second bearing hole (45) is elastically deformable. The rear head (43) rotatably supports the auxiliary shaft portion (29) of the drive shaft (25) by the second bearing portion (44).
As illustrated in FIG. 4, the first cylinder (35) has a first bush hole (47) and a first blade hole (48). The first bush hole (47) and a second blade hole (58) penetrate the first cylinder (35) in the axial direction (thickness direction). Each of the first bush hole (47) and the first blade hole (48) has a substantially circular shape. The first bush hole (47) is open to the first cylinder hole (36) in the radial direction. The first blade hole (48) is located outside the first bush hole (47) in the radial direction, and communicates with the first bush hole (47).
A pair of first bushes (49) is fitted in the first bush hole (47). Each of the first bushes (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) is freely oscillatable about the centerline of the first bush hole (47). The pair of first bushes (49) sandwiches a first blade (52), which will be described later, and restricts rotation of a first piston (50) on its own axis.
The first cylinder chamber (37) houses the first piston (50). The first piston (50) has a first roller (51) and the first blade (52). The first roller (51) is an annular member. The first eccentric portion (27) of the drive shaft (25) is fitted in the hollow of the first roller (51). The outer peripheral surface of the first roller (51) is in contact with the inner peripheral surface of the first cylinder (35) so as to be slidable in the circumferential direction. The first roller (51) rotates together 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.
The first blade (52) is provided on the outer peripheral surface of the first roller (51), and extends outward in the radial direction of the first roller (51). The first blade (52) is sandwiched between the pair of first bushes (49) so as to be movable back and forth. A tip end portion of the first blade (52) is housed in the first blade hole (48). In the first cylinder chamber (37), a first operation space (53) for compressing the 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 blade (52) divides the first operation space (53) into a first low-pressure chamber and a first high-pressure chamber.
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) is open in the inner peripheral surface of the first cylinder (35) and communicates with the first low-pressure chamber at a position adjacent to the first bushes (49) (position on the right side of the first bushes (49) in FIG. 4). The other end of the first suction passage (54) is open in the outer peripheral surface of the first cylinder (35) and forms an inflow end. The first suction pipe (15) is connected to the inflow end of the first suction passage (54) (see FIG. 3).
A first discharge passage (55) is formed in the front head (31). The first discharge passage (55) penetrates the front head (31) in the axial direction. One end of the first discharge passage (55) is open in the lower surface of the front head (31) and communicates with the first high-pressure chamber at a position on the opposite side to the first suction passage (54) with respect to the first bushes (49) (position on the left side of the first bushes (49) in FIG. 4). The other end of the first discharge passage (55) is open in the upper surface of the front head (31).
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, for example, a reed valve. The first discharge valve (56) is in a closed state closing the first discharge passage (55) while a gas pressure in the first high-pressure chamber is lower than a gas pressure in the casing (11) (dome internal pressure). The first discharge valve (56) is in an open state opening the first discharge passage (55) when the gas pressure in the first high-pressure chamber exceeds the dome internal pressure.
As illustrated in FIG. 5, the second cylinder (40) has a second bush hole (57) and a second blade hole (58). The second bush hole (57) and the second blade hole (58) penetrate the second cylinder (40) in the axial direction (thickness direction). Each of the second bush hole (57) and the second blade hole (58) has a substantially circular shape. The second bush hole (57) is open to the second cylinder hole (41). The second blade hole (58) is located outside the second bush hole (57) in the radial direction of the second cylinder (40), and communicates with the second bush hole (57).
A pair of second bushes (59) is fitted in the second bush hole (57). Each of the second bushes (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) is freely oscillatable about the centerline of the second bush hole (57). The pair of second bushes (59) sandwiches a second blade (62), which will be described later, and restricts rotation of a second piston (60) on its own axis.
The second cylinder chamber (42) houses the second piston (60). The second piston (60) has a second roller (61) and the second blade (62). The second roller (61) is an annular member. The second eccentric portion (28) of the drive shaft (25) is fitted in the hollow of the second roller (61). The outer peripheral surface of the second roller (61) is in contact with the inner peripheral surface of the second cylinder (40) so as to be slidable in the circumferential direction. The second roller (61) rotates together 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.
The second blade (62) is provided on the outer peripheral surface of the second roller (61), and extends outward in the radial direction of the second roller (61). The second blade (62) is sandwiched between the pair of second bushes (59) so as to be movable back and forth. A tip end portion of the second blade (62) is housed in the second blade hole (58). In the second cylinder chamber (42), a second operation space (63) for compressing the 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 blade (52) divides the second operation space (63) into a second low-pressure chamber and a second high-pressure chamber.
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).
The cylinder-side passage (65) extends in the radial direction in the second cylinder (40). One end of the cylinder-side passage (65) is open in the inner peripheral surface of the second cylinder (40) and communicates with the second low-pressure chamber at a position adjacent to the second bushes (59) (position on the right side of the second bushes (59) in FIG. 5). The other end of the cylinder-side passage (65) is open in a surface (lower surface in FIG. 3) on the rear head (43) side, and forms an inflow end. The head-side passage (66) extends in the radial direction in the rear head (43). As illustrated in FIG. 3, the head-side passage (66) has a first passage (66a) and a second passage (66b).
The first passage (66a) extends outward in the radial direction of the rear head (43). One end of the first passage (66a) is open in the outer peripheral surface of the rear head (43), and forms an inflow end. The second suction pipe (16) is connected to the inflow 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 upward of the first passage (66a) in the axial direction. One end of the second passage (66b) is open in the upper surface of the rear head (43), and forms an outflow end. The outflow end of the second passage (66b) corresponds to the inflow end of the cylinder-side passage (65), and communicates with the second cylinder chamber (42) through the cylinder-side passage (65).
This configuration can increase the distance between the first suction pipe (15) and the second suction pipe (16) as compared with a case in which the second suction pipe (16) is connected to the second cylinder (40). A distance L1 between the center (C1) of a portion of the first suction pipe (15) penetrating the barrel (12) of the casing (11) and the center (C2) of a portion of the second suction pipe (16) penetrating the barrel (12) of the casing (11), and a distance L2 between the center (C3) of the first cylinder chamber (37) in the height direction and the center (C4) of the second cylinder chamber (42) in the height direction satisfy a relational expression given by Expression (1) below: $L 1 > L 2$
As illustrated in FIG. 5, a second discharge passage (67) is also formed in the rear head (43). The second discharge passage (67) penetrates the rear head (43) in the axial direction. One end of the second discharge passage (67) is open in the upper surface of the rear head (43) and communicates with the second high-pressure chamber at a position on the opposite side to the second suction passage (64) with respect to the second bushes (59) (position on the left side of the second bushes (59) in FIG. 5). The other end of the second discharge passage (67) is open in the lower surface of the rear head (43).
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, for example, a reed valve. The second discharge valve (68) is in a closed state closing the second discharge passage (67) while a gas pressure in the second high-pressure chamber is lower than the dome internal pressure. The second discharge valve (68) is in an open state opening the second discharge passage (67) when the gas pressure in the second high-pressure chamber exceeds the dome internal pressure.
In the compression mechanism (30), the first piston (50) eccentrically rotates in the first cylinder chamber (37) along with rotation of the drive shaft (25). When the volume of the first low-pressure chamber gradually increases along with the eccentric rotation of the first piston (50), the refrigerant flowing through the first suction pipe (15) is sucked through the first suction passage (54) into the first low-pressure chamber. Further eccentric rotation of the first piston (50) causes isolation of the first low-pressure chamber from the first suction passage (54), and the isolated space serves as the first high-pressure chamber.
The gas pressure in the first high-pressure chamber increases as the volume of the first high-pressure chamber gradually decreases along with further eccentric rotation of the first piston (50). When the gas pressure in the first high-pressure chamber exceeds the dome internal pressure, the first discharge valve (56) is opened, and the refrigerant in the first high-pressure chamber flows out of the compression mechanism (30) through the first discharge passage (55).
As the drive shaft (25) rotates, the second piston (60) rotates eccentrically in the second cylinder chamber (42) along with the eccentric rotation of the first piston (50). When the volume of the second low-pressure chamber gradually increases along with the eccentric rotation of the second piston (60), the refrigerant flowing through the second suction pipe (16) is sucked through the second suction passage (64) into the second low-pressure chamber. Further eccentric rotation of the second piston (60) causes isolation of the second low-pressure chamber from the second suction passage (64), and the isolated space serves as the second high-pressure chamber.
The gas pressure in the second high-pressure chamber increases as the volume of the second high-pressure chamber gradually decreases along with further eccentric rotation of the second piston (60). When the gas pressure in the second high-pressure chamber exceeds the dome internal pressure, the second discharge valve (68) is opened, and the refrigerant in the second high-pressure chamber flows out of the compression mechanism (30) through the second discharge passage (67).
The high-pressure refrigerant having 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) or other portions of the stator (22). Then, the high-pressure refrigerant having flowed upward of the electric motor (21) is transferred to the refrigerant circuit (1a) through the discharge pipe (17).

As illustrated in FIG. 2, an accumulator (80) is connected upstream of the rotary compressor (10). The accumulator (80) temporarily stores the refrigerant to be sucked into the rotary compressor (10) and performs gas-liquid separation for the liquid refrigerant and oil contained in the gas refrigerant. The accumulator (80) includes a closed container (81), an inlet pipe (82), a first outlet pipe (83), and a second outlet pipe (84).
The closed container (81) is configured as a vertically long cylindrical member. The inlet pipe (82) is a pipe through which the refrigerant flows into the closed container (81). The inlet pipe (82) is connected to an upper portion of the closed container (81). The lower end of the inlet pipe (82) is open to the internal space of the closed container (81) at a position near the top of the closed container (81). The upper end of the inlet pipe (82) is connected to the refrigerant circuit (1a).
The first outlet pipe (83) and the second outlet pipe (84) are pipes through which the refrigerant flows out of the closed container (81). The first outlet pipe (83) and the second outlet pipe (84) are connected to a lower portion of the closed container (81). The first outlet pipe (83) and the second outlet pipe (84) have upper end portions extending in the up-and-down direction in the closed container (81) and opening to the internal space of the closed container (81) at a position near the top of the closed container (81).
The first outlet pipe (83) has a lower end portion which extends downward from the lower end of the closed container (81), bends toward the first suction pipe (15) of the rotary compressor (10), and is connected to the first suction pipe (15). The second outlet pipe (84) has a lower end portion which extends downward from the lower end of the closed container (61), bends toward the second suction pipe (16) of the rotary compressor (10), and is connected to the second suction pipe (16).

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). As illustrated 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) are not distinguished from each other and are referred to as a diameter Ds.
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) are not distinguished from each other and are referred to as an eccentric distance Le. The "eccentric distance Le1 of the first piston (50)" described herein means a 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 a distance from the axis (AC) of the drive shaft (25) to the center (C6) of the second piston (60).
The thickness Tm of the middle plate (38) is designed in relation to the diameters Ds of the first cylinder chamber (37) and the second cylinder chamber (42). Specifically, 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) satisfy a relational expression given by Expression (2) below: $1 / 30 \leq Tm / Ds \leq 1 / 10$
The relational expression given by Expression (2) above is obtained based on a calculation expression relating to deflection and stress of a circular plate with a hole.
As illustrated 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 deflection amount y_max of the middle plate (38) is expressed by Expression (3) below according to a calculation expression for the structural model illustrated in FIG. 7, relating to deflection and stress of a circular plate with a hole.
[Math 1] $y_{\max} = k \cdot \frac{P \cdot a^{4}}{E \cdot {Tm}^{3}}$ wherein "k" is a coefficient variable according to the value of a/b; "a" is the radius of a region of the middle plate (38) facing the first operation space (53) or the second operation space (63) (hereinafter referred to as the "outer radius of the middle plate (38)"); and "b" is the radius of a portion of the middle plate (38) overlapping with the first piston (50) or the second piston (60) in the region facing the first operation space (53) or the second operation space (63) (hereinafter referred to as the "inner radius of the middle plate (38)"). The inner radius b of the middle plate (38) is expressed by b = a-e, wherein "e" is a distance corresponding to a difference between the outer radius a and 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 a load applied to the middle plate (38) in the thickness direction. "E" is the elastic modulus of the middle plate (38).
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 therefore is expressed by a = Ds/2. When Expression (3) above is modified based on the above-described point, Expression (4) below is obtained.
[Math 2] $\frac{y_{\max}}{Tm} = k \cdot \frac{P}{16 \cdot E} \cdot {(\frac{Ds}{Tm})}^{4}$
From Expression (4) above, the ratio (y_max/Tm) of the deflection amount y_max to the thickness Tm of the middle plate (38) is proportional to (Ds/Tm)⁴.
FIG. 8 is a graph showing a relationship between an index value y_max/Tm indicating the deflection amount of the middle plate (38) on the left side of the above Expression (4) and Ds/Tm on the right side of the above Expression (4). The data of FIG. 8 are calculated on the assumption that the middle plate (38) is made of cast iron (E = 110 GPa) and that a pressure difference between the first cylinder chamber (37) and the second cylinder chamber (42) is 3 MPa (P = 3 MPa). As illustrated in FIG. 8, the index value y_max/Tm indicating the deflection amount of the middle plate (38) increases as the value of Ds/Tm increases.
Further, when a calculation is performed for a case in which the diameters 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, it is found that the deflection amount of the middle plate (38) can be sufficiently smaller than the first gap and the second gap (10 µm or less) if the function Ds/Tm is in a range of 10 or more and 30 or less, as illustrated in FIG. 9. From this point, 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 relational expression (1/30 ≤ Tm/Ds ≤ 1/10) expressed by Expression (2) above.
The diameter Da of the main shaft portion (26) is designed in relation to the diameters Ds of the first cylinder chamber (37) and the second cylinder chamber (42). Specifically, the diameters 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 a relational expression given by Expression (5) below. Thus, the diameter Da of the main shaft portion (26) of this example is designed to be relatively smaller than the diameters Ds of the first cylinder chamber (37) and the second cylinder chamber (42). $Da \leq Ds \times 0.35$
The eccentric distances Le of the first piston (50) and the second piston (60) are designed in relation to the radii Rs of the first cylinder chamber (37) and the second cylinder chamber (42). Specifically, the radii Rs of both the first cylinder chamber (37) and the second cylinder chamber (42) and the eccentric distances Le of the first piston (50) and the second piston (60) satisfy a relational expression given by Expression (6) below: $Le / Rs \leq 0.25$
As described above, the outer radius a of the middle plate (38) is expressed by a = Ds/2, and the inner radius b of the middle plate (38) is expressed by b = a-e. When Expression (6) above is modified based on the above-described point, Expression (7) below is obtained. $a / b \leq 1.333$
In this case, the coefficient k in Expression (3) above can be considered to be 0.00077, assuming that the case is similar to a case of a/b = 1.25 in a known table showing a relationship between the coefficient k and a/b. Further, when Expression (4) above is modified, Expression (8) below is obtained.
[Math 3] $\frac{y_{\max}}{Tm} = k \cdot \frac{P}{E} \cdot {(\frac{a}{Tm})}^{4}$
Further, since a/Tm = 0.5 × Ds/Tm, Expression (9) below is obtained by modifying Expression (2) above. $5 \leq a / Tm \leq 15$
In Expression (8) above, when E = 110 GPa and P = 3 MPa for the data of FIG. 8, the range of y_max/Tm is expressed by Expression (10) below from Expression (9) above. $0.000013 \leq y_{\max} / Tm \leq 0.0001$
Thus, by designing the ratio (Le/Rs) between the radius Rs of each of the first cylinder chamber (37) and the second cylinder chamber (42) and the eccentric distance Le of each of the first piston (50) and the second piston (60) to an appropriate range so as to satisfy Expression (6) above, it is possible to reduce the deflection of the middle plate (38) to 1/1000 or less of the thickness Tm.

-Features of 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 diameters 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 each of the first cylinder chamber (37) and the second cylinder chamber (42), the deflection of the middle plate (38) in response to the pressure of the fluid compressed in the first cylinder chamber (37) and the second cylinder chamber (42) can be suitably reduced. Further, when the thickness Tm of the middle plate (38) is 1/10 or less of the diameter Ds of each 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 reduced. This can reduce deflection of the drive shaft (25). Thus, the reliability of the rotary compressor (10) with a reduced diameter of the drive shaft (25) can be improved.
In the rotary compressor (10) of this embodiment, the distance L1 between the centers (C1, C2) of the portions of the first suction pipe (15) and the second suction pipe (16) penetrating the casing (11) is larger 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. This configuration can ensure the strength of the portions of the casing (11) where the first suction pipe (15) and the second suction pipe (16) penetrate.
In the rotary compressor (10) of this embodiment, the ratio (Le/Rs) between the eccentric distance Le of the first piston (50) and the radius Rs of the first cylinder chamber (37) and the ratio (Le/Rs) between 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. Thus, based on a calculation expression relating to deflection and stress of a circular plate with a hole, the deflection amount of the middle plate (38) can be suitably reduced and can be extremely small with respect to the thickness of the middle plate (38). This is advantageous in improving the reliability of the rotary compressor (10).
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 achieve the specific configuration in which the distance L1 between the centers (C1, C2) of the portions of the first suction pipe (15) and the second suction pipe (16) 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. Moreover, the first suction pipe (15) is connected to the first cylinder (35). Thus, as compared with a case where the first suction pipe (15) is connected to the front head (31), the flow path through which refrigerant flowing toward the compression mechanism (30) via the first suction pipe (15) reaches the first cylinder chamber (37) can be shortened, thereby reducing a refrigerant pressure loss.
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 of the diameter Ds of the first cylinder chamber (37) or the second cylinder chamber (42). When the diameter Da of the main shaft portion (26) is relatively small as described above, a friction loss between the main shaft portion (26) and the front head (31) can be reduced. This can increase the compression efficiency of the rotary compressor (10). On the other hand, the drive shaft (25) having the main shaft portion (26) with a relatively small diameter is likely to deflect during operation of the rotary compressor (10). In the rotary compressor (10) including such a drive shaft (25), the technique of the present disclosure is particularly effective as it can reduce the deflection of the drive shaft (25).
In the rotary compressor (10) of this embodiment, the first annular groove (34) is formed in the end face of the front head (31) facing the middle plate (38). According to this configuration, the first bearing portion (32) of the front head (31) is elastically deformable between the first annular groove (34) and the first bearing hole (33). The second annular groove (46) is also formed in the end face of the rear head (43) facing the middle plate (38). According to this configuration, the second bearing portion (44) of the rear head (43) is elastically deformable between the second annular groove (46) and the second bearing hole (45).
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). The resultant compression load is applied to the drive shaft (25), causing deflection of the drive shaft (25) in the radial direction. When the drive shaft (25) deflects, the first bearing portion (32) and the second bearing portion (44) are elastically deformed to the first annular groove (34) side or the second annular groove (46) side in response to the deflection of the drive shaft (25), and deflect together with the drive shaft (25). This makes it possible to prevent the drive shaft (25) from coming into strong and partial contact with the front head (31) or the rear head (43), thereby reducing wear between the drive shaft (25) and each of the first bearing portion (32) and the second bearing portion (44).
In the rotary compressor (10) of this embodiment, the maximum number of rotations of the drive shaft (25) is 120 rps or more, which is relatively high. As the rotational speed of the drive shaft (25) increases, the deflection of the drive shaft (25) tends to become larger. In the rotary compressor (10) operated with a relatively great number of rotations as described above, the technique of the present disclosure is particularly effective as it can reduce the deflection of the drive shaft (25).
The refrigeration apparatus (1) of this embodiment includes the rotary compressor (10). In the rotary compressor (10), the reliability of the rotary compressor (10) with a reduced diameter of the drive shaft (25) can be improved. With this rotary compressor (10), the refrigeration apparatus (1) can improve energy efficiency while maintaining reliability, owing to the higher compression efficiency achieved by reducing the diameter of the drive shaft (25).

-First Variation-

In the rotary compressor (10) of the first variation, as illustrated in FIG. 10, the main shaft portion (26) and auxiliary shaft portion (29) of the drive shaft (25) are designed to have different diameters Da and Db. Specifically, in the drive shaft (25), the diameter Da of the main shaft portion (26) and the diameter Db of the auxiliary shaft portion (29) satisfy a relational expression given by Expression (11) below. $Db < Da$
In the rotary compressor (10) of the first variation, the diameter Db of the auxiliary shaft portion (29) of the drive shaft (25) supported by the rear head (43) is smaller than the diameter Da of the main shaft portion (26) supported by the front head (31). When the diameter Db of the auxiliary shaft portion (29) is smaller than the diameter Da of the main shaft portion (26), the friction loss between the auxiliary shaft portion (29) and the rear head (43) can be reduced as compared with a case where the diameter Db of the auxiliary shaft portion (29) and the diameter Da of the main shaft portion (26) are the same. This is advantageous in increasing the compression efficiency of the rotary compressor (10).

-Second Variation-

As illustrated in FIG. 11, in the rotary compressor (10) of the second variation, the connection portions of the first suction pipe (15) and the second suction pipe (16) are different from those of the above-described 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 the cylinder-side passage (65) and the head-side passage (66), similarly to the second suction passage (64) of the above-described embodiment. The second suction passage (64) is formed similarly to the first suction passage (54) of the above-described embodiment.

-Third Variation-

As illustrated in FIG. 12, in the rotary compressor (10) of the third variation, the connection portion of the first suction pipe (15) is different from that of the above-described 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 by the cylinder-side passage (65) and the head-side passage (66), similarly to the second suction passage (64) of the above-described embodiment. Moreover, the second suction pipe (16) is formed by the cylinder-side passage (65) and the head-side passage (66), similarly to the above-described embodiment.

<<Other Embodiments>>

As illustrated in FIG. 13, the compression mechanism (30) of the rotary compressor (10) of the above-described embodiment may be of a rolling piston type in which the first blade (52) of the first piston (50) is formed separately from the first roller (51). In such a compression mechanism (30), the flat plate-shaped first blade (52) is fitted in a first blade groove (90) extending in the radial direction of the first cylinder (35) so as to be movable back and forth, and the first bushes (49) are omitted. The first blade (52) is pressed against the outer peripheral surface of the first roller (51) by a spring (91). The tip end portion of the first blade (52) is in contact with the outer peripheral surface of the first roller (51) so as to be slidable. The same may also be applied to the second piston (60).
The diameter Ds1 of the first cylinder chamber (37) and the diameter Ds2 of the second cylinder chamber (42) may differ from each other. In this case, at least the smaller one of the diameter Ds1 of the first cylinder chamber (37) or the diameter Ds2 of the second cylinder chamber (42) is referred to as the diameter Ds. The diameter Ds satisfies the relational expression (1/30 ≤ Tm/Ds ≤ 1/10) given in Expression (2) above. 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 relational expression given by Expression (2) above.
The first annular groove (34) does not have to be formed in the lower surface of the front head (31). The second annular groove (46) does not have to 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 face of one of the front head (31) or the rear head (43) facing the middle plate (38), and only one of the first bearing portion (32) or the second bearing portion (44) may be partially elastically deformable.
The compression mechanism (30) may be configured as a two-stage compression type in which the refrigerant compressed in one of the first cylinder chamber (37) or the second cylinder chamber (42) is further compressed in the other. The compression mechanism (30) may include three or more cylinders. For example, the compression mechanism (30) may have a structure in which the front head (31), the first cylinder (35), a first middle plate corresponding to the middle plate (38), the second cylinder (40), a second middle plate, a third cylinder, and the rear head (43) are stacked on one another.
While the embodiments and 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 foregoing embodiments and variations thereof may be combined and replaced with each other without deteriorating the intended functions of the present disclosure.

INDUSTRIAL APPLICABILITY

As described above, the present disclosure is useful for a rotary compressor and a refrigeration apparatus.

DESCRIPTION OF REFERENCE CHARACTERS

1: Refrigeration Apparatus
10: Rotary Compressor
11: Casing
15: First Suction Pipe
16: Second Suction Pipe
21: Electric Motor
25: Drive Shaft
26: Main Shaft Portion
29: Auxiliary Shaft Portion
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: Axis

Claims

A rotary compressor comprising:
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 on one another; and

a drive shaft (25) provided so as to penetrate the compression mechanism (30) in a stacking direction and rotatably supported by the first head (31) and the second head (43),

inside the first cylinder (35), a first cylinder chamber (37) defined by the first head (31) and the middle plate (38) being formed,

the first cylinder chamber (37) housing a first piston (50) configured to rotate eccentrically along with rotation of the drive shaft (25) and thereby compress a fluid sucked into the first cylinder chamber (37),

inside the second cylinder (40), a second cylinder chamber (42) defined by the middle plate (38) and the second head (43) being formed,

the second cylinder chamber (42) housing a second piston (60) configured to rotate eccentrically along with rotation of the drive shaft (25) and thereby compress a fluid sucked into the second cylinder chamber (42),

diameters Ds of both the first cylinder chamber (37) and the second cylinder chamber (42) or a smaller one of the diameters Ds and a thickness Tm of the middle plate (38) satisfying a relational expression expressed as 1/30 ≤ Tm/Ds ≤ 1/10.
The rotary compressor of claim 1, further comprising:
a casing (11) configured to house the compression mechanism (30) and the drive shaft (25);

a first suction pipe (15) configured to suck a fluid into the first cylinder chamber (37); and

a second suction pipe (16) configured to suck a fluid into the second cylinder chamber (42), wherein

each of the first suction pipe (15) and the second suction pipe (16) penetrates the casing (11), and

a distance L1 between a center (C1) of a portion of the first suction pipe (15) penetrating the casing (11) and a center (C2) of a portion of the second suction pipe (16) penetrating the casing (11), and a distance L2 between a center (C3) of the first cylinder chamber (37) in a height direction and a center (C4) of the second cylinder chamber (42) in a height direction satisfy a relational expression expressed as L1 > L2.
The rotary compressor of claim 1 or 2, wherein
the first piston (50) and the second piston (60) are eccentric with respect to an axis (AC) of the drive shaft (25), and

an eccentric distance Le of the first piston (50) or the second piston (60) 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) relate to the diameter Ds satisfying the relational expression and satisfy a relational expression expressed as Le/Rs ≤ 0.25.
The rotary compressor of 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).
The rotary compressor of 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).
The rotary compressor of any one of claims 1 to 5, further comprising:
an electric motor (21) coupled to the drive shaft (25), wherein

the electric motor (21) is disposed at a position at which the first head (31) is interposed between the electric motor (21) and the first cylinder (35),

the drive shaft (25) has a main shaft portion (26) supported by the first head (31), and

the diameter Ds satisfying the relational expression and a diameter Da of the main shaft portion (26) satisfy a relational expression expressed as Da ≤ Ds × 0.35.
The rotary compressor of any one of claims 1 to 6, further comprising:
an electric motor (21) coupled to the drive shaft (25), wherein

the electric motor (21) is disposed at a position at which the first head (31) is interposed between the electric motor (21) and the first cylinder (35),

the drive shaft (25) has a main shaft portion (26) supported by the first head (31) and an auxiliary shaft portion (29) supported by the second head (43), and

a diameter Da of the main shaft portion (26) and a diameter Db of the auxiliary shaft portion (29) satisfy a relational expression expressed as Db < Da.
The rotary compressor of any one of claims 1 to 7, wherein
the first head (31) and the second head (43) have bearing holes (33, 45) through which the drive shaft (25) is inserted, and

an annular groove (34, 46) extending along a periphery of the bearing hole (33, 45) is formed in an end face of the first head (31) or the second head (43) facing the middle plate (38).
The rotary compressor of any one of claims 1 to 8, wherein
a maximum number of rotations of the drive shaft (25) is 120 rps or more.
A refrigeration apparatus comprising:
the rotary compressor (10) of any one of claims 1 to 9.