1 DESCRIPTION HERMETIC COMPRESSOR 5 Technical Field This invention relates to a hermetic compressor, specifically a discharge passage for a refrigerant and a lubricating oil. 10 Background Art A hermetic compressor of a type to which the present invention relates comprises a scroll unit arranged inside a hermetic container to perform a process of sucking in, compressing and discharging a refrigerant, and supplies a 15 lubricating oil to the scroll unit and a scroll-unit driving part. The lubricating oil not only lubricates sliding surfaces of the scroll unit, bearings, etc., but also seals the sliding surfaces. The lubricating oil is held in an oil holding chamber at the bottom of the 20 hermetic container and circulates inside the hermetic container, temporarily mixing with the refrigerant. If a large amount of the lubricating oil is discharged with the refrigerant through a discharge hole after serving as a lubricant and a sealant in relevant parts inside the 25 container, it leads to problems, such as unsatisfactory lubrication and a reduction in thermal efficiency. In order not to allow the lubricating oil to be discharged with the refrigerant but to guide it to the oil holding chamber at the bottom of the hermetic container, 30 there are known a configuration including an oil discharge passage or an oil discharge guide provided on an inner wall surface of the container body, and a configuration including an oil discharge pipe extending along the inner 2 wall surface of the container body (see patent documents 1, 2 and 3). In many cases, the refrigerant is discharged from the hermetic container through a discharge pipe fitted at the 5 top of the hermetic container. However, when the discharge pipe is fitted at the top of the hermetic container, the hermetic compressor requires a device provided above the scroll unit to guide the lubricant oil and refrigerant discharged from the scroll unit, toward the oil holding 10 chamber at the bottom of the hermetic container, thereby preventing them from flowing directly into the discharge pipe. This results in an increase in components, and the hermetic compressor is likely to have a complicated structure. 15 In view of this, the aforementioned patent documents each disclose a configuration with a discharge pipe fitted at the body of the hermetic container, resulting in a simplified structure above the scroll unit. Patent document 1: Japanese Patent Application Laid 20 open No. Hei 9-287579 Publication Patent document 2: Japanese Patent Application Laid open No. 2004-316500 Publication Patent document 3: Japanese Patent Application Laid open No. 2006-132419 Publication 25 The configurations disclosed in the patent documents may reliably guide the lubricating oil and refrigerant toward the oil holding chamber at the bottom of the hermetic container by virtue of having the oil discharge 30 passage or the like, but do not ensure that the lubricating oil and the refrigerant are satisfactorily separated from each other, and thus, are still likely to experience the discharge of a large amount of the lubricating oil with the 3 refrigerant, and problems caused by this, such as unsatisfactory lubrication and a reduction in thermal efficiency. Further, the fitting of the discharge pipe at the body 5 of the hermetic container accompanies a problem of how to discharge the refrigerant smoothly and efficiently from the hermetic container, minimizing its interference with the components of the hermetic compressor. The present disclosure addresses some of the above 10 problems. An object is to provide a hermetic compressor which has a simplified structure and can satisfactorily separate a lubricating oil from a refrigerant and efficiently discharge the refrigerant from a hermetic container. 15 Summary In an aspect there is provided, a hermetic compressor comprising a hermetic container including a cylindrical body and defining a discharge chamber to an upper side of 20 the body and a lubricating oil holding chamber to a lower side of the body, an interior of the body being at discharge pressure; a rotary shaft extending inside the body and rotatably supported by a bearing; an electric motor disposed inside the body to drive the rotary shaft by 25 being supplied with current, the electric motor including a rotor fixed on the rotary shaft to cause the rotary shaft to rotate integrally with it, a stator including coils and disposed to surround the rotor to cause the rotor to rotate, and a supply passage through the stator to guide a 30 lubricating oil to the oil holding chamber; a compression unit disposed inside the body, above the electric motor, to perform a process of sucking in, compressing and discharging a refrigerant by being driven by the rotary 4 shaft; a primary shaft frame disposed between the compression unit and the electric motor to allow the compression unit to be fixed thereon and receive the rotary shaft supported by the bearing; a discharge passage 5 extending at least either through the compression unit and the primary shaft frame, or between an inner wall surface of the body and the compression unit and primary shaft frame, to guide the refrigerant compressed by the compression unit and the lubricating oil contained therein 10 from the discharge chamber directly to the stator; an oil separation plate disposed over the stator and having a plurality of constriction holes arranged in a concentric circle in a top plan view to make the lubricating oil separate from the refrigerant when they pass through the 15 construction holes, an oil discharge passage for guiding the lubricating oil separated from the refrigerant by means of the oil separation plate to turn approximately at a right angle and flow in a radial direction of the rotary shaft and a discharge pipe fitted to the body, below the 20 primary shaft frame, to allow the refrigerant having passed through the oil separation plate and the stator to be discharged from the hermetic container. The discharge passage may be a pipe extending at least either through the compression unit and the primary shaft 25 frame, or between the inner wall surface of the body and the compression unit and primary shaft frame, toward the stator. The discharge passage may include a hole extending through the compression unit and the primary shaft frame. 30 The hermetic container may further comprise wires laid on the inner wall surface of the body to operate the electric motor, the discharge pipe being in a position opposite to the wires with the rotary shaft between.
5 In the hermetic compressor, the refrigerant with the lubricating oil is conveyed to the stator through the oil discharge passage. The oil discharge passage mayextend at 5 least either through the compression unit and the primary shaft frame, or between the inner wall surface of the body and the compression unit and primary shaft frame, and the refrigerant is discharged from the hermetic container through the discharge pipe fitted at the body of the 10 hermetic container. Thus, the hermetic compressor does not require a device (discharge head) provided above the compression unit to guide the lubricant oil and refrigerant toward the oil holding chamber at the bottom of the hermetic container, thereby preventing them from flowing 15 directly into the discharge pipe. The hermetic container can therefore have a simplified upper structure, resulting in a reduction in costs. The refrigerant with the lubricating oil passes through not only the oil separation plate but also the 20 stator having coils. This ensures that the lubricating oil is separated from the refrigerant so that only the refrigerant is satisfactorily discharged from the hermetic container. In the hermetic compressor, the discharge passage may 25 be provided in the form of a pipe. Thus, with a simple structure, the refrigerant with the lubricating oil is reliably guided toward the stator of the electric motor. In the hermetic the discharge passage may include a hole extending through the compression unit and the primary 30 shaft frame. This enables the refrigerant with the lubricating oil to be reliably guided toward the stator of the electric motor with a simpler structure, and also enables a reduction in costs.
6 In the hermetic compressor, the discharge pipe may be in a position opposite to the wires connected to the electric motor, with the rotary shaft between. This allows the refrigerant to be smoothly and efficiently discharged 5 from the hermetic container, minimizing its interference with the wires connected to the electric motor. Brief Description of the Drawings FIG. 1 is a vertical cross-sectional view of a 10 hermetic compressor according to the present invention, and FIG. 2 is a cross-sectional view along line A-A in FIG. 1. Explanation of the Reference Characters 15 1 Hermetic compressor 2 Housing (hermetic container) 3 Body 6 Motor 8 Stator 20 12 Rotary shaft 14 Primary shaft frame 30 Scroll unit 32 Stationary scroll 52 Movable scroll 25 60 Discharge chamber 72 Discharge pipe 90 Discharge passage 96 Oil separation plate 98 Discharge hole 7 100 Wires Best Mode of Carrying out the Invention With reference to the drawings, the mode of carrying 5 out the present invention will be described below in detail. Embodiment FIG. 1 is a vertical cross-sectional view of a hermetic compressor according to the present invention. 10 The compressor 1 is a scroll compressor and incorporated in a refrigeration circuit of a refrigeration system, a heat pump water heater or the like. The circuit provides a path along which carbon dioxide refrigerant (hereinafter referred to simply as "refrigerant"), which is 15 an example of a working fluid, circulates. The compressor 1 sucks in and compresses the refrigerant, thereby forcing it to circulate along the path. The compressor 1 has a housing (hermetic container) 2. A body 3 of the housing 2 is hermetically sealed with upper 20 and lower covers 4, 5 hermetically fitted in the body 3 at the top and bottom thereof, respectively. The interior of the body is at high discharge pressure. An electric motor (electromotor, hereinafter referred to simply as "motor") 6 is disposed inside the body 3, and 25 a rotary shaft 12 is disposed inside the motor 6. Specifically, the motor 6 includes a rotor 7 including a permanent magnet and fixed on the rotary shaft 12, and a stator 8 having coils 9 and disposed to surround the rotor 7. The stator 8 is press-fitted in the body 3 to be fixed 30 with a part thereof in contact with the body. Current supplied to the coils 9 generates a rotating electromagnetic field, which causes the rotor 7 to rotate, and thus, causes the rotary shaft 12 to rotate integrally 8 with the rotor. The rotary shaft 12 is rotatably supported by a bearing 16 within a primary shaft frame 14, at the upper side. The primary shaft frame 14 is fixedly joined to the body 3 by welding or the like. 5 Above the motor 6 is disposed a shielding member 80, which allows the primary shaft frame 14 to be inserted through it and extends radially up to near the rim of the stator 8. The shielding member 80 thus divides the outer circumferential part of the stator 8 from the other part of 10 the stator 8 and the rotor 7. The rotary shaft 12 is rotatably supported by a bearing 20 within a secondary shaft frame 18, at the lower side. An oil pump 22 is provided at the lower end of the rotary shaft 12. The pump 22 draws up a lubricating oil 15 from an oil holding chamber 12 inside the lower cover 5. The lubricating oil, which ascends in an oil passage 24 extending axially through the rotary shaft 12, is supplied from the upper end of the rotary shaft 12 to the motor 6, the scroll unit (compression unit) 30, etc. to lubricate 20 sliding parts, bearings, etc. and seal the sliding surfaces. The frame 18 has a lubricating oil introduction hole 19 at an appropriate location so that the lubricating oil supplied to the sliding parts of the compressor 1 can be collected into the oil holding chamber 23 through the 25 introduction hole 19 as described below. The scroll unit 30 is disposed inside the body 3, above the motor 6, to perform a process of sucking in, compressing and discharging the refrigerant. Specifically, the scroll unit 30 comprises a movable scroll 52 and a 30 stationary scroll 32. The movable scroll 52 comprises a plate portion 54 and a spiral wrap integrally formed on the plate portion 54, and is disposed with the spiral wrap directed to a plate portion 34 of the stationary scroll 32 9 so that the spiral wraps of the movable and stationary scrolls define compression pockets between them. As the movable scroll 32 orbits relative to the stationary scroll 32, the compression pockets move from the radially outer 5 end of the spiral wrap toward the center thereof, reducing their volumes, and thus, the refrigerant trapped in the compression pockets is compressed. In order to cause the movable scroll 52 to perform the orbital motion, the movable scroll has a boss 66 on the 10 lower side of the plate portion 54. The boss 66 is rotatably supported by a bearing 28 on an eccentric shaft 26. The eccentric shaft 26 is integrally formed on top of the rotary shaft 12. The movable scroll 52 is prevented from rotating about its axis by a rotation prevention pin 15 68. The stationary scroll 32 is fixed on the primary shaft frame 14, and its plate portion 34 divides a compression chamber from a discharge chamber 60. The stationary scroll 32 has a discharge hole 36 extending through the plate 210 portion 34 to connect to the compression chamber, at an appropriate location in the center. As seen in FIG. 1, the discharge chamber 60 is connected to the rotor 7 and stator 8 of the motor 6 by a discharge passage 90. In other words, the discharge 25 passage 90 is provided to guide the refrigerant containing the lubricating oil from the discharge chamber 60 to the top of the stator 8. Specifically, the discharge passage 90 consists of a passage 92 in the form of a hole extending through the 30 scroll unit 30 and the primary shaft frame 14, and a pipe 94 connected to the passage 92. The pipe 94 extends through the shielding member 80 to guide the refrigerant containing the lubricating oil directly to the top of the 10 stator 8. Over the stator 8 is disposed an oil separation plate 96 to separate the lubricating oil from the refrigerant conveyed through the discharge passage 90. 5 Thus, the refrigerant containing the lubricating oil, entering the discharge chamber 60 from the compression chamber and conveyed through the discharge passage 90, is separated into the refrigerant and the lubricating oil, while passing through the oil separation plate 96 and the 10 stator 8. FIG. 2 is a cross-sectional view along line A-A in FIG. 1, showing the top plan view of the oil separation plate 96. As seen in this Figure, the oil separation plate 96 has a plurality of constriction holes 98 arranged in a 15 concentric circle in the top plan view. The refrigerant containing the lubricating oil is separated into the compressed refrigerant and the lubrication oil by passing through these constriction holes 98. More specifically, the refrigerant and the lubricating 20 oil are separated from each other, not only with the oil separation plate 98, but also by the lubricating oil adhering to the coils 9 while flowing down through the stator 8 having the coils 9. The refrigerant and the lubricating oil are therefore reliably separated from each 25 other. A discharge pipe 72 is fitted to the body 3, below the primary shaft frame 14, and the refrigerant with the lubricating oil removed is discharged from the housing 2, or the compressor 1 through the discharge pipe 72. 30 Specifically, as seen in FIG. 2, wires 100 to operate the motor 6 are laid on the inner wall surface of the body 3, and the discharge pipe 72 is in a position opposite to the wires 100 with the rotary shaft 12 between.
11 In the compressor 1 structured as described above, the rotation of the rotary shaft 12 causes the movable scroll 52 to perform an orbital motion without rotating about its axis. By the movable scroll 52 performing the orbital 5 motion, the refrigerant is sucked in through the suction pipe 70, and compressed and transferred from the radially outer end of the scroll unit 30 to the center thereof by the compression pockets moving toward the center while reducing their volumes. As a result, the refrigerant 10 compressed to high pressure, with tiny droplets of the lubricating oil suspended therein, due to stirring, is discharged into the discharge chamber 60 through the discharge hole 36. The refrigerant then flows through the discharge passage 90 and flows around inside the housing 2 15 and leaves the compressor 1 through the discharge pipe 72 fitted at the body 3. From the refrigerant compressed to high pressure and containing the lubricating oil, the lubricating oil is reliably separated at the oil separation plate 98 and the 20 stator 8, so that only the refrigerant is discharged from the compressor 1 through the discharge pipe 72. The lubricating oil separated from the refrigerant drops down and enters the oil chamber 23 at the bottom of the housing 2, through the introduction hole 19, and is held therein. 25 The lubricating oil supplied to the scroll unit 30, the bearings 16, 28, etc. is guided by an oil discharge passage 84 to turn approximately at a right angle, then flows down through the stator 8, similarly to the compressed refrigerant containing the lubricating oil, 30 conveyed through the discharge passage 90. The lubricating oil then enters the oil holding chamber 23 through the introduction hole 19 and is held therein. As stated above, the hermetic compressor according to 12 the present invention has a discharge passage 90 to guide the refrigerant with the lubricating oil directly to the top of the stator 8 of the motor 6, and a discharge pipe 72 fitted to the body 3, below the primary shaft frame 14. 5 The hermetic compressor with the discharge pipe 72 fitted to the body 3 does not require a discharge head, which would be provided above the scroll unit 30 according to the prior art, and thus, the housing 2 can have a simplified upper structure, resulting in a reduction in 10 costs. The discharge passage 90 guides the refrigerant containing the lubricating oil directly to the stator 8, and the refrigerant containing the lubricating oil passes through not only the oil separation plate 96 but also the 15 stator 8 having coils 9. This ensures that the refrigerant and the lubricating oil are separated from each other so that only the refrigerant is satisfactorily discharged from the compressor 1. In the described embodiment, the discharge passage 90 20 consists of a passage 92 in the form of a hole extending through the scroll unit 30 and the primary shaft frame 14 and a pipe (copper pipe, for example) 94 connected to the passage 92. Thus, with a simple structure attributed to the use of the pipe 94, the refrigerant with the 25 lubricating oil is reliably guided to the stator 8 of the motor 6. Also the fact that the passage 92 in the form of a hole constitutes part of the discharge passage 90 contributes to structural simplification and reduction in costs. 30 The discharge pipe 72 is in a position opposite to the wires 100 with the rotary shaft 12 between. This allows the refrigerant with the lubricating oil removed to be smoothly and efficiently discharged from the compressor 1, 13 minimizing its interference with the wires 96 connected to the motor 6. In the above, an embodiment of the present invention has been described. The present invention is however not 5 limited to the described embodiment, but can be modified in various ways without departing from the scope and spirit thereof. For example, in the above embodiment, the discharge passage 90 consists of a passage 92 in the form of a hole 10 extending through the scroll unit 30 and the primary shaft frame 14 and a pipe 94 connected to the passage 92. The discharge passage 90 may however consist only of a pipe 94. Such pipe 94 may be provided to extend through the scroll unit 30 and the primary shaft frame 14, or between the 15 inner wall surface of the body 3 and the scroll unit 30 and primary shaft frame 14. In this case, the discharge chamber 60 is connected to the rotor 7 and stator 8 only by the pipe 94. If possible, the discharge passage 90 may consist only of a passage 92 in the form of a hole 20 extending through the primary shaft frame 14. In this case, the discharge chamber 60 is connected to the rotor 7 and stator 8 only by the passage 92 in the form of a hole. In the above embodiment, the compressor 1 is a hermetic scroll compressor including a scroll unit 30. The 25 present invention is however applicable to not only the scroll compressor but also other types of the hermetic compressor performing a process of sucking in, compressing and discharging a refrigerant. 30 Industrial Applicability The present invention can provide a hermetic compressor which has a simplified structure and can satisfactorily separate a lubricating oil from a 14 refrigerant and efficiently discharge the refrigerant from a hermetic container. Such hermetic compressor has a wide range of applications including air conditioning, freezing, refrigeration and hot-water supply. 5 In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, 10 i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. It is to be understood that, if any prior art publication is referred to herein, such reference does not 15 constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.