Patent Publication Number: US-11378080-B2

Title: Compressor

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a U.S. national stage application of International Application PCT/JP2018/009993 filed on Mar. 14, 2018, the contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a compressor, and in particular, relates to a structure for reducing the volume of space in a shell. 
     BACKGROUND ART 
     In existing apparatuses each including a refrigeration cycle circuit, such as air-conditioning apparatuses, a compressor, a condenser, a pressure reducing device, and an evaporator are connected by pipes, and refrigerant is circulated to exchange heat with air. As refrigerant for use in the air-conditioning apparatuses, R32 and R410A are primarily adopted, and have high global warming potentials (GWPs), that is, a GWP value of 675 and a GWP value of 2090, respectively. By contrast, some air-conditioning apparatuses use natural refrigerants. For example, R290 has a GWP value of 3, which is a low value, but it is highly flammable refrigerant. 
     In a refrigeration cycle circuit employing highly flammable refrigerant, it is necessary to reduce the amount of refrigerant provided in the circuit in order to prevent, even if the refrigerant leaks into a given space, the concentration of the refrigerant in the space from falling within a flammable range that is a concentration range of refrigerant that will burn. In order to do so, it is also necessary to reduce the volume of a compressor, which occupies a large volume in the refrigeration cycle circuit. For example, in a hermetic motor-driven compressor disclosed in Patent Literature 1, the distance between a compression mechanism and a motor is small, and as a result the volume of the hermetic motor-driven compressor is also small. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Unexamined Patent Application Publication No. 8-261152 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the hermetic motor-driven compressor disclosed in Patent Literature 1, since the distance between the compression mechanism and the motor is small, an insulation distance between the compression mechanism and coils of the motor is also small. Thus, an insulating plate is provided between the coils of the motor and components of the compression mechanism. Inevitably, the insulating plate provided between the coils of the motor and the component of the compression mechanism hinders circulation of lubricating oil in the hermetic motor-driven compressor. Furthermore, since the space in a shell of the hermetic motor-driven compressor is small in volume, the distance from the compression mechanism to a discharge port through which the refrigerant flows out of the compressor is also small. In such a manner, because the distance from the compression mechanism to the discharge port is small, the lubricating oil does not easily separate from gas refrigerant containing the lubricating oil. Consequently, after flowing out of the hermetic motor-driven compressor, the lubricating oil is dispersed in a refrigeration cycle circuit. 
     The present disclosure is applied to solve the above problems, and relates to a compressor in which a sufficient insulation distance is ensured between a motor and a compression mechanism, and the amount of lubricating oil that flows out along with refrigerant discharged from the compressor is reduced, while the volume of the compressor is reduced. 
     Solution to Problem 
     A compressor according to an embodiment of the present disclosure includes: a compression mechanism that compresses refrigerant; a motor unit provided above the compression mechanism to drive the compression mechanism; a shell that houses the compression mechanism and the motor unit; and a lower insulating member provided between the compression mechanism and the motor unit. The motor unit includes a stator fixed to the shell, and a rotor spaced from an inner circumferential surface of the stator by a predetermined gap. The rotor has a rotor passage that causes spaces located above and below the motor unit to communicate with each other, and the lower insulating member is located in a region outward of the inner circumferential surface of the stator. 
     Advantageous Effects of Invention 
     According to the embodiment of the present disclosure, an appropriate insulation distance is ensured between the motor unit and the compression mechanism, and the lubricating oil is separated from the refrigerant in the compressor, while the volume of the compressor is reduced. It is therefore possible to reduce the amount of refrigerant enclosed in a refrigeration cycle circuit in which the compressor is located, and adopt highly flammable refrigerant. Thus, a refrigeration cycle apparatus having a low GWP can be achieved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram illustrating a section of a compressor according to Embodiment 1. 
         FIG. 2  is a top plan view of a compression mechanism as illustrated in  FIG. 1 . 
         FIG. 3  is a schematic diagram illustrating a section of a compressor according to Embodiment 2. 
         FIG. 4  is a perspective view of an example of a lower insulating member included in the compressor according to Embodiment 2. 
         FIG. 5  is a schematic diagram illustrating a section of a compressor according to Embodiment 3. 
         FIG. 6  is a schematic diagram illustrating a section of a compressor according to Embodiment 4. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
       FIG. 1  is a schematic diagram illustrating a section of a compressor  100  according to Embodiment 1. The compressor  100  compresses refrigerant that is circulated in a refrigeration cycle circuit included in an apparatus such as an air-conditioning apparatus. As the refrigerant, a flammable refrigerant or a slightly flammable refrigerant can be used. In the refrigeration cycle circuit including the compressor  100  according to Embodiment 1, as the refrigerant, any of R290, R600a, R32, R454B, R1234yf, and R1234ze is used. R290 and R600a are flammable refrigerants and classified as A3, and R32, R454B, R1234yf, and R1234ze are slightly flammable refrigerants and classified as A2L. The compressor  100  includes a shell  10  as an outer shell, and has a suction port  14  located in lower part of the shell  10  and a discharge port  15  located in upper part of the shell  10 . In the compressor  100 , the refrigerant that circulates in the refrigeration cycle circuit flows into the compressor  100  through the suction port  14 , and is compressed by a compression mechanism  20 . The compressed refrigerant is discharged from the shell  10  to the refrigeration cycle circuit through the discharge port  15 . The suction port  14  is connected with an accumulator  2 . The refrigerant that circulates in the refrigeration cycle circuit is separated into gas refrigerant and liquid refrigerant in the accumulator  2  and flows into the compressor  100 . 
     In the shell  10 , the compression mechanism  20  and a motor unit  30  are provided. The refrigerant sucked through the suction port  14  is compressed by the compression mechanism  20 . In the shell  10 , the compressed refrigerant is discharged from the compression mechanism  20 . Then, in the shell  10 , the discharged refrigerant passes through a region in which the motor unit  30  is located, and is discharged to the refrigeration cycle circuit through the discharge port  15  provided in the upper part of the shell  10 . 
     (Compression Mechanism  20 ) 
     In Embodiment 1, the compression mechanism  20  is a rotary compression mechanism  20  including a cylinder  21 , a rolling piston  22 , an upper bearing  23 , a lower bearing  24 , and a vane (not illustrated). However, the compression mechanism  20  may be another type compression mechanism, such as a scroll type compression mechanism or a reciprocating type compression mechanism. 
     In the compression mechanism  20 , the cylinder  21  and the rolling piston  22  are provided between a lower surface of the upper bearing  23  and an upper surface of the lower bearing  24 . The rolling piston  22  is provided in an internal space of the cylinder  21 , and is located on an outer circumferential side of an eccentric portion  62  of a main shaft  60  coupled to the motor unit  30 . The rolling piston  22  is rotated by the main shaft  60  in the internal space of the cylinder  7 , and thus compresses together with the vane, the refrigerant. The compressed refrigerant is discharged through a discharge opening portion  25  in the upper bearing  23  located above the cylinder  21 . 
     At the discharge opening portion  25 , a discharge valve is provided. When a pressure in the cylinder  21  is higher than that in the shell  10 , the discharge valve is pressed upwards, whereby the refrigerant is discharged from the cylinder  21 . When the pressure in the cylinder  21  is lower than that in the shell  10 , the discharge opening portion  25  is closed by the discharge valve. 
     The upper bearing  23  and the lower bearing  24  serve as bearings for the main shaft  60 , and support along with a rotor  32 , the main shaft  60  being rotated. The upper bearing  23  and the lower bearing  24  have respective cylindrical portions over which the main shaft  60  is slidable. In the following, the cylindrical portions may also be each referred to as a main shaft bearing. 
       FIG. 2  is a top plan view of the compression mechanism  20  as illustrated in  FIG. 1 . To an upper surface of the compression mechanism  20 , a muffler member  26  is attached in such a manner as to cover the discharge opening portion  25 . In an upper surface of the muffler member  26 , an opening portion  27  is formed. The refrigerant is discharged through the discharge opening portion  25  into space defined by the muffler member  26  and the upper surface of the compression mechanism  20 , and is then discharged into space in the shell  10  through the opening portion  27 . 
     (Motor Unit  30 ) 
     The motor unit  30  includes a stator  31  and the rotor  32 . The stator  31  has an outer circumferential surface fixed to an inner wall of the shell  10 . The stator  31  includes a plurality of coils arranged circularly. The coils are formed by winding wires made of, for example, copper or aluminum, around an iron core. Between the coils and the iron core, an electrical insulating material is provided to reduce leak current. In the motor unit  30 , current flows through the coils of the stator  31  to produce a magnetic field, thereby driving the rotor  32 . 
     The rotor  32  is cylindrical, and to a central portion of the rotor  32 , the main shaft  60  is attached. The rotor  32  is spaced from an inner circumferential surface of the stator  31  by a predetermined gap. The rotor  32  is driven and rotated by the magnetic field produced by the stator  31 , thereby rotating the main shaft  60 . The main shaft  60  transmits a driving force produced by the rotor  32  to the compression mechanism  20 . 
     The rotor  32  has a rotor passage that causes spaces located above and below the motor unit  30  to communicate with each other. For example, the rotor passage is, for example, a hole that extends through the rotor  32  in a vertical direction. The refrigerant can move from the compression mechanism  20  toward the discharge port  15  through the rotor passage 
     (Lower Insulating Member  40 ) 
     Since current flows through the coils of the stator  31 , the compression mechanism  20  is spaced from the motor unit  30  by a predetermined distance to achieve insulation between the compression mechanism  20  and the motor unit  30 . In Embodiment 1, a lower insulating member  40  is provided in the space between the motor unit  30  and the compression mechanism  20  located below the motor unit  30 . The lower insulating member  40  is provided at a location outward of the inner circumferential surface of the stator  31 . Also, the lower insulating member  40  is located in a region extending from a lower end face of the stator  31  to a position close to the upper surface of the compression mechanism  20 . Furthermore, the lower insulating member  40  is, for example, cylindrical, and is provided in such a manner to reduce the space in a region between the motor unit  30  and the compression mechanism  20 . The lower insulating member  40  is located close to an outer circumferential surface of the muffler member  26  attached to the upper surface of the compression mechanism  20  such that the lower insulating member  40  does not hinder the flow of the refrigerant discharged from the muffler member  26  through the opening portion  27  upward an upper region in the shell  10 . It should be noted that the shape of the lower insulating member  40  is not limited to the cylindrical shape. The lower insulating member  40  may be provided in part of the region between the motor unit  30  and the compression mechanism  20 . It is not indispensable that the lower insulating member  40  has a continuous cylindrical shape. For example, the lower insulating member  40  can be formed to have divided portions arranged cylindrically. 
     The lower insulating member  40  may have a width that is at least equal to a coil length of each of the coils of the stator  31  between an inner circumferential edge and an outer circumferential edge of the stator  31 . Because of provision of such a configuration, a passage from each coil to a peripheral component has a greater length, thus preventing leak current. 
     The lower insulating member  40  may be formed integrally with the insulating material of the stator  31  of the motor unit  30 , or may be fixed to the stator  31 . The lower insulating member  40  can be fixed to the stator  31  by, for example, a fastener such as a screw, or by welding or bonding. 
     (Upper Insulating Member  50 ) 
     In Embodiment 1, an upper insulating member  50  is provided in a region above the motor unit  30 . The upper insulating member  50  is located at a location outward of the inner circumferential surface of the stator  31 . Furthermore, the upper insulating member  50  is located in a region above an upper end face of the stator  31 , and is provided in such a manner to reduce the space above the motor unit  30  in the shell  10 . The upper insulating member  50  may be cylindrically shaped, as well as the lower insulating member, or may be provided in part of the region above the stator  31 . In Embodiment 1, an oil separator  64  is provided above the rotor  32 . The upper insulating member  50  is separated from the oil separator  64  by a predetermined distance, and located outward of the oil separator  64 . 
     (Flow of Refrigerant in Shell  10 ) 
     The flow of the refrigerant in the compressor  100  according to Embodiment 1 will be described with reference to  FIG. 1 . The refrigerant sucked through the suction port  14  is compressed by rotating the rolling piston  22  in the internal space of the cylinder  21  in the compression mechanism  20 . The compressed refrigerant is discharged through the discharge opening portion  25  into the space defined by the muffler member  26  and the upper surface of the compression mechanism  20 . Then, the refrigerant flows out of the muffler member  26  through the opening portion  27  provided in the upper surface of the muffler member, and enters the region between the compression mechanism  20  and the motor unit  30 . The lower insulating member  40  is provided close to the outer circumferential surface of the muffler member  26 , and the refrigerant thus does not easily flow toward the outer circumferential surface of the muffler member  26 . The refrigerant mostly flows into a first passage which is a hole extending in the vertical direction, through the rotor  32  located above the muffler member  26 . 
     The refrigerant that has flowed into the first passage flows upwards and strikes against the oil separator  64  located above the rotor  32  and attached to the main shaft  60 . Then, the refrigerant flows upwards around the oil separator  64  and flows into the discharge port  15  provided in the upper part of the shell  10 . 
     The refrigerant is in a gaseous state in the shell  10 . When compressed in the compression mechanism  20 , the refrigerant is discharged together with lubricating oil, from the compression mechanism  20 . The lubricating oil moves together with the refrigerant that flows in the above manner, and the lubricating oil collects as it moves upwards, and then flows downwards in the shell  10  because of gravity. In such a manner, the lubricating oil flows downwards, and is thus separated from the refrigerant. The lubricating oil does not easily flow to the refrigeration cycle circuit. 
     In particular, since the shell  10  is formed to have a great length in the vertical direction, the lubricating oil can be easily separated from the refrigerant. In the compressor  100  according to Embodiment 1, a path from the compression mechanism  20  to the discharge port  15  is long. The lubricating oil can be easily separated from the refrigerant when the refrigerant is flowing. In  FIG. 1 , arrows indicate the flow of the refrigerant. The oil separator  64  is located on a path along which the refrigerant flows to reach the discharge port  15 , and the refrigerant flows around the oil separator  64 . As a result, the path along which the refrigerant flows is long, whereby the lubricating oil can be easily separated from the refrigerant. 
     In Embodiment 1, the lower insulating member  40  and the upper insulating member  50  are arranged along the path along which the refrigerant flows. Thus, the lubricating oil touches and adheres to the lower insulating member  40  and the upper insulating member  50 , and can thus be easily separated from the refrigerant. 
     Furthermore, in the shell  10 , a main passage in which refrigerant flows is located on inner circumferential sides of the lower insulating member  40 , the stator  31 , and the upper insulating member  50 . Between the inner wall of the shell  10  and each of the lower insulating member  40 , the stator  31 , and the upper insulating member  50 , passages are provided to cause an upper region located above the lower insulating member  40 , the stator  31 , and the upper insulating member  50  and a lower region located below the lower insulating member  40 , the stator  31 , and the upper insulating member  50  to communicate with each other. The lubricating oil separated from the refrigerant and adhering to the inner wall of the shell  10  passes through the above passage and reaches a lubricating oil sump  16  provided in the lower part of the shell  10 . The passage provided between an outer circumferential surface of the lower insulating member  40  and the inner wall of the shell  10  will be referred to as a lower insulating-member passage  80 . The passage provided between the outer circumferential surface of the stator  31  and the inner wall of the shell  10  will be referred to as a stator circumferential passage  81 . The passage provided between an outer circumferential surface of the upper insulating member  50  and the inner wall of the shell  10  will be referred to as an upper insulating-member passage  82 . 
     As illustrated in  FIG. 1 , each of the lower insulating member  40  and the upper insulating member  50  is spaced from the inner wall of the shell  10  by a gap. However, the lower insulating member  40  and the upper insulating member  50  may be provided in contact with the inner wall of the shell  10 . In this case, in outer circumferential surfaces of the lower insulating-member passage  80  and the upper insulating-member passage  82 , grooves are provided. The grooves and the inner wall of the shell  10  define the lower insulating-member passage  80  and the upper insulating-member passage  82 . 
     In the compressor  100 , the refrigerant compressed by the compression mechanism  20  passes through the passages indicated by the arrows in  FIG. 1  and reaches the discharge port  15 . Thus, the lubricating oil is separated from the refrigerant, and at the same time the refrigerant is discharged out of the compressor  100 . The lower insulating member  40  and the upper insulating member  50  are arranged outside the inner circumferential surface of the stator  31 , and thus reduce the volume of the shell  10  without hindering the flow of the refrigerant. In addition, on the outer circumferential side of the lower insulating member  40 , the lower insulating-member passage  80  is provided, and on the outer circumferential side of the upper insulating member  50 , the upper insulating-member passage  82  is provided, thereby providing passages through which the lubricating oil separated from the refrigerant and adhering to the inner wall of the shell  10  returns to the lubricating oil sump  16 . The lower insulating-member passage  80  and the upper insulating-member passage  82  are separated from the main passage for the flow of the refrigerant by the lower insulating member  40  and the upper insulating member  50 , thereby enabling the lubricating oil to efficiently return to the lubricating oil sump  16 . 
     As illustrated in  FIG. 2 , an upper surface of the upper bearing  23  corresponds to an upper surface of the compression mechanism  20 , and the upper bearing  23  has compression-mechanism passages  28  that extend through the compression mechanism  20 . In Embodiment 1, the upper bearing  23  has an outer circumferential surface fixed to the inner wall of the shell  10 . The circumference of each of the cylinder  21  and the lower bearing  24  is smaller than that of the upper bearing  23 . In particular, the cylinder  21  and the lower bearing  24  each have an outer circumferential surface located inward of the compression-mechanism passages  28  arranged in the upper bearing  23 . Thus, the compression-mechanism passages  28  cause regions above and below the compression mechanism  20  to communicate with each other. 
     The compression-mechanism passages  28  are arranged below the upper insulating-member passage  82 , the stator circumferential passage  81 , and the lower insulating-member passage  80 . It is therefore possible to efficiently return the lubricating oil that flows from an upper region, to the lubricating oil sump  16 . 
     Embodiment 2 
     In a compressor  200  according to Embodiment 2, the lower insulating member  40  of the compressor  100  according to Embodiment 1 is modified. Embodiment 2 will be described by referring mainly to the difference between Embodiments 1 and 2. 
       FIG. 3  is a schematic diagram illustrating a section of the compressor  200  according to Embodiment 2. In the compressor  200 , a lower insulating member  240  is provided in the region between the lower end face of the stator  31  and the upper surface of the compression mechanism  20 . A lower end face of the lower insulating member  240  is in contact with the upper surface of the compression mechanism  20 , that is, the upper surface of the upper bearing  23 . 
     Since the lower insulating member  240  is in contact with the upper surface of the compression mechanism  20 , the lower insulating member  240  can be easily positioned in the shell  10 . For example, after the compression mechanism  20  is fixed to a shell cylindrical member  12 , the lower insulating member  240  is inserted into the shell cylindrical member  12  and is brought into contact with the upper surface of the compression mechanism  20 , whereby the lower insulating member  240  is positioned. After that, the stator  31  of the motor unit  30  is inserted into the shell cylindrical member  12 , and is moved until the stator  31  is brought into contact with the lower insulating member  240 , thereby positioning the compression mechanism  20 , the lower insulating member  240 , and the stator  31 . 
     In the compression mechanism  20 , the outer circumferential surface of the upper bearing  23  is fixed to the shell cylindrical member  12  by, for example, spot welding or caulking. The stator  31  is fixed to the shell cylindrical member  12  by, for example, shrink fitting, caulking, or spot welding. 
     In Embodiment 2, when the lower insulating member  240  is in contact with the stator  31  and the compression mechanism  20 , the distance between the stator  31  and the compression mechanism  20  is determined. Thus, at the time of assembly, it is possible to set the stator  31  and the compression mechanism  20  without a jig, while accurately determining the distance between the stator  31  and the compression mechanism  20 . Furthermore, a flow passage through which the refrigerant compressed by the compression mechanism  20  flows and a return passage through which the lubricating oil returns to the lubricating oil sump  16  are ensured as in Embodiment 1. 
       FIG. 4  is a perspective view of an example of the lower insulating member  240  of the compressor  200  according to Embodiment 2. The lower insulating member  240  has a lower end face  242  or lower end faces  242 . To be more specific, in the lower insulating member  240 , a single lower end face  242  may be provided. Alternatively, a plurality of lower end faces  242  may be provided and arranged in a circumferential direction as illustrated in  FIG. 4 . In this case, the lower end faces  242  of the lower insulating member  240  do not close the compression-mechanism passages  28  provided in the compression mechanism  20 . Thus, the passage in which the lubricating oil returns to the lubricating oil sump  16  is ensured. To be more specific, the lower insulating member  240  has recesses  244  in its lower portion such that the recesses  244  are arranged in such a manner as to correspond to the compression-mechanism passages  28 , thereby ensuring the passage through the lubricating oil flows. In addition, since the lower end face or faces  242  of the lower insulating member  240  are brought into contact with the upper surface of the compression mechanism  20 , an appropriate distance between the stator  31  and the compression mechanism  20  is ensured. 
     Referring to in  FIG. 4 , the lower insulating member  240  has a single flat upper end face  241 . However, the shape of the upper end face  241  can be appropriately changed in order that the upper end face  241  be in contact with the stator  31 . For example, upper end faces  241  may be provided as portions to be in contact with insulating portions of the stator  31 . Furthermore, the upper end face  241  may be shaped in accordance with the shape of the stator  31 . 
     Embodiment 3 
     In a compressor  300  according to Embodiment 3, a lower portion of the lower insulating member  40  of the compressor  100  according to Embodiment 1 is modified such that the lower portion also serves as the muffler member  26  of the compression mechanism  20 . Embodiment 3 will be described by referring mainly to the difference between Embodiments 1 and 3. 
       FIG. 5  is a schematic diagram illustrating a section of the compressor  300  according to Embodiment 3. In Embodiment 3, a lower portion of a lower insulating member  340  serves as a muffler member  326 . The muffler member  326  is shaped in such a manner as to cover the discharge opening portion  25  of the compression mechanism  20 . The muffler member  326  has a lower end face  342  that is in contact with the upper surface of the compression mechanism  20 . The muffler member  326  and the upper surface of the compression mechanism  20  define space into which the compressed refrigerant is discharged. 
     The muffler member  326  is made of a resin material. Preferably, the muffler member  326  should be made of an electrical insulating material. The muffler member  326  is, for example, a molded component made of a resin material. The muffler member  326  is shaped such that the muffler member  326  has a great thickness to have required rigidity and strength and to reduce the volume of the space between the motor unit  30  and the compression mechanism  20 . Furthermore, the muffler member  326  is coupled to the lower insulating member  340  by coupling members  346  such as screws or bolts. That is, the muffler member  326  and the lower insulating member  340  are provided as a single component. 
     Since the lower insulating member  340  and the muffler member  326  are provided as a single component, the lower end face of the muffler member  326  is in contact with the upper surface of the compression mechanism  20  as in Embodiment 2. Because of such a configuration, the single component that is a combination of the lower insulating member  340  and the muffler member  326  serves as a positioning mechanism that accurately sets the compression mechanism  20  and the stator  31  such that the distance between the compression mechanism  20  and the stator  31  is set to a correct distance. For example, after the compression mechanism  20  is fixed to the shell cylindrical member  12 , the single component that is the combination of the lower insulating member  340  and the muffler member  326  is inserted into the shell cylindrical member  12 , and the muffler member  326  is brought into contact with the compression mechanism  20 . Then, the stator  31  is brought into contact with an upper end face  341  of the lower insulating member  340  and is positioned at the shell cylindrical member  12 . As a result, it is ensued that the distance between the stator  31  and the compression mechanism  20  is accurately determined without using a jig at the time of assembly. 
     In an upper surface of the muffler member  326 , an opening  327  is formed. The refrigerant is discharged from the compression mechanism  20  through the discharge opening portion  25  into the space defined by the muffler member  326 , and then flows into the opening  327 . In Embodiment 3, since the lower insulating member  340  is located at a location outward of the inner circumferential surface of the stator  31 , the refrigerant that has flowed out through the opening  327  flows toward the discharge port  15  without being obstructed by the lower insulating member  340 . 
     In Embodiment 3, since the muffler member  326  combined with the lower insulating member  340  is made to have a great thickness, the muffler member  326  can reduce the volume of space located inward of the inner circumferential surface of the stator  31  in the region between the motor unit  30  and the compression mechanism  20 . It is therefore possible to more greatly reduce the volume of the inside of the compressor  300  than in Embodiments 1 and 2, thus further reducing the amount of refrigerant provided in the refrigeration cycle circuit. 
     Embodiment 4 
     In a compressor  400  according to Embodiment 4, the upper insulating member  500  in the compressor  100  according to Embodiment 1 is modified to further have an oil separator function. Embodiment 4 will be described by referring mainly to the difference between Embodiments 1 and 4. 
       FIG. 6  is a schematic diagram illustrating a section of the compressor  400  according to Embodiment 4. In Embodiment 4, an upper insulating member  450  and an oil separator member  464  are combined into a single component. The oil separator member  464  is shaped in such a manner as to cover the rotor  32 . The refrigerant that have passed through the holes provided in the rotor  32  strikes against the oil separator member  464 , passes through lubricating-oil separation holes  466  and  467  provided in the oil separator member  464 , and flows to the discharge port  15 . The oil separator member  464  includes a bypass structure  465 . The oil separator member  464  and the bypass structure  465  are shaped in such a manner as to increase the length of a passage through which the refrigerant flows. Thus, when moving together with the refrigerant toward the upper part of the shell  10 , the lubricating oil adheres to the oil separator member  464  and the bypass structure  465 , and then flows downwards toward the lower part of the shell  10 . 
     The oil separator member  464  is coupled to the upper insulating member  450  by coupling members  456  such as screws or bolts. The oil separator member  464  and the bypass structure  465  can be made of, for example, a resin material. The oil separator member  464  and the bypass structure  465  can be made to have a great thickness and can thus reduce the volume of the space above the motor unit  30 . Furthermore, since the oil separator member  464  and the bypass structure  465  are provided in such a manner as to cover the upper side of the rotor  32 , the oil separator member  464  and the bypass structure  465  can more greatly reduce the space above the motor unit  30  than the upper insulating member  50  in Embodiment 1. Therefore, in the compressor  400 , it is possible to further reduce the amount of refrigerant provided in the refrigeration cycle circuit than in Embodiment 1. 
     The upper insulating member  450 , the oil separator member  464 , and the bypass structure  465  in the compressor  400  according to Embodiment 4 may be incorporated into each of the compressors  100 ,  200 , and  300  according to Embodiments 1 to 3. In this case, it is possible to further reduce the volume of the shell  10 , thus further reducing the amount of refrigerant provided in the refrigeration cycle circuit. 
     REFERENCE SIGNS LIST 
       2  accumulator  7  cylinder  10  shell  12  shell cylindrical member  14  suction port  15  discharge port  16  lubricating oil sump  20  compression mechanism  21  cylinder  22  rolling piston  23  upper bearing  24  lower bearing discharge opening portion  26  muffler member  27  opening portion  28  compression-mechanism passage  30  motor unit  31  stator  32  rotor  40  lower insulating member  50  upper insulating member  60  main shaft  61  main shaft  62  eccentric portion  64  oil separator  80  lower insulating-member passage  81  stator circumferential passage  82  upper insulating-member passage  100  compressor  200  compressor  240  lower insulating member  241  upper end face  242  lower end face  244  recess  300  compressor  326  muffler member  327  opening portion  340  lower insulating member  341  upper end face  342  lower end face  346  coupling member  400  compressor  450  upper insulating member  456  coupling member  464  oil separator member  465  bypass structure  466  lubricating-oil separation hole  467  lubricating-oil separation hole