Patent Description:
In general, a compressor is a machine used for generating high pressure or transporting a high-pressure fluid, and in the case of being applied to a refrigeration cycle of a refrigerator or an air conditioner, serves to compress refrigerant gas and transfer the compressed refrigerant gas to a condenser. Scroll compressors are mainly applied to large air conditioners such as system air conditioners installed in buildings.

In a scroll compressor, a fixed scroll is fixed in an inner space of a casing, and an orbiting scroll may be engaged with the fixed scroll to perform an orbiting motion. Suction, gradual compression and discharge of refrigerant are continuously and repeatedly carried out through compression chambers continuously formed between a fixed wrap of the fixed scroll and an orbiting wrap of the orbiting wrap.

Recently, a bottom-compression type high pressure compressor is provided in which a compression unit including a fixed scroll and an orbiting scroll is disposed below a motor unit transferring driving force to turn the orbiting scroll so as to directly receive refrigerant gas, compress the gas, and discharge the compressed gas to an upper space inside a casing. This is disclosed in <CIT> (Patent Document <NUM>).

In the case of such a bottom-compression type scroll compressor, the refrigerant discharged into the inner space of the casing moves to a refrigerant discharge tube located at an upper portion of the casing, while oil is returned to an oil storage space defined below the compression unit. At this time, there is a burden that the oil is mixed with the refrigerant to be discharged to the outside of the compressor or is pushed by the pressure of the refrigerant to thereby stagnate at an upper side of the motor unit.

In addition, in the case of the bottom-compression type, oil is mixed with refrigerant discharged from the compression unit and moves upward through the motor unit (driving motor), and at the same time, oil above the motor unit moves downward through the motor unit. Therefore, the oil that is moving downward may be mixed with the refrigerant discharged from the compression unit to be then discharged to the outside of the compressor, or may fail to move to the lower side of the motor unit due to the refrigerant of high pressure that is moving upward. Then, as an amount of oil returned to the oil storage space is rapidly reduced, an amount of oil supplied to the compression unit is decreased, causing friction loss or wear of the compression unit. <CIT> (Patent Document <NUM>) discloses a technique for separating a refrigerant discharge path and an oil discharge path by providing a flow path guide between a motor unit and a compression unit. In the flow path guide disclosed in Patent Document <NUM>, an outer wall is formed in an annular shape, and a space between a compression unit and a motor unit is divided into an inner space defining a refrigerant discharge passage and an outer space defining an oil return passage. <CIT> relates to a scroll type compressor capable of bypassing refrigerant compressed by a compressing assembly for delivery to a discharger. <CIT> relates to a scroll compressor with a refrigerant discharge flow passage and an oil recovery flow passage separated from each other to improve efficiency and reliability of the compressor.

In the bottom-compression type scroll compressor, a liquid refrigerant may stagnate inside the casing as the internal temperature of the casing does not reach an oil superheat when it is stopped at a low temperature or when it is initially started. Then, as low-viscosity oil is supplied to the compression unit and bearing surfaces, damage to the compression unit and the bearing surfaces may occur. In addition, when an internal temperature of the casing reaches an oil superheat in a state in which liquid refrigerant stagnates inside the casing, the liquid refrigerant dissolved in the oil is vaporized and discharged to the outside of the compressor. At this time, the oil may leak together with vaporized gas refrigerant, thereby causing a shortage of oil inside the casing. This may cause aggravated damage to the compression unit and the bearing surfaces. These drawbacks may be severe in a low-temperature environment or in a large compressor applied to an air conditioning system in a building. Particularly, since the large compressor has a larger inner space, a large quantity of liquid refrigerant is introduced when the compressor is initially started but a time to reach an oil superheat as a condition of vaporizing the liquid refrigerant may be delayed. As a result, the aforementioned problems may be further aggravated, and efficiency and reliability of the air conditioning system may be deteriorated.

The invention is defined by independent claims. The present disclosure describes a scroll compressor capable of suppressing a decrease in oil viscosity or a shortage of oil inside a casing, and an air conditioner having the same.

The present disclosure also describes a scroll compressor capable of suppressing liquid refrigerant from stagnating in an inner space of a casing, and an air conditioner having the same.

The present disclosure further describes a scroll compressor capable of suppressing liquid refrigerant from stagnating in an inner space of a casing by employing a device for discharging the liquid refrigerant from the inner space of the casing, and an air conditioner having the same.

The present disclosure further describes a scroll compressor capable of more rapidly discharging liquid refrigerant from the inner space of a casing while simplifying a device for discharging the liquid refrigerant, and an air conditioner having the same.

The present disclosure further describes a scroll compressor capable of enhancing efficiency and reliability of an air conditioner, to which the scroll compressor is applied, and an air conditioner having the same.

In order to achieve the aspects and other advantages of the subject matter disclosed herein, a liquid refrigerant discharge unit may be disposed to induce liquid refrigerant stagnated in a casing toward a refrigerant discharge tube. This can suppress the liquid refrigerant from excessively stagnating in a compressor during an initial operation of the compressor.

In addition, in order to achieve those aspects of the present disclosure, a venturi tube may be disposed inside or outside the casing. Accordingly, a venturi effect of a fluid discharged at a high flow rate from the inside of the casing can be used, thereby simplifying the liquid refrigerant discharge unit.

Furthermore, in order to achieve those aspects of the subject matter disclosed herein, a venturi tube or a refrigerant discharge tube may be installed at a position with a high flow rate and an end of the liquid refrigerant discharge tube may be installed at a position with a low flow rate. This can effectively discharge stagnated liquid refrigerant while enhancing a venturi effect.

Specifically, the scroll compressor according to an implementation may include a casing, a motor unit, a compression unit, a refrigerant discharge tube, a venturi tube, and a liquid refrigerant discharge tube. The casing may have a hermetic inner space. The motor unit may be disposed in the inner space of the casing to operate a rotating shaft. The compression unit may be disposed at one side of the motor unit in the inner space of the casing, and include a discharge passage through which refrigerant compressed while the compression unit is driven by the rotating shaft is discharged into the inner space of the casing. The refrigerant discharge tube may have one end communicating with the inner space of the casing and another end connected to a refrigeration cycle, such that the refrigerant discharged into the inner space of the casing flows to the refrigeration cycle. The venturi tube may be disposed adjacent to the refrigerant discharge tube in the inner space of the casing. The liquid refrigerant discharge tube may have a first end connected to the venturi tube and a second end communicating with the inner space of the casing at a lower side of the refrigerant discharge tube. This can suppress liquid refrigerant from excessively stagnating in the inner space of the casing.

According to the invention, an inner passage through which spaces of both sides of the motor unit in the axial direction can communicate with each other may be defined inside the motor unit. The venturi tube may be formed such that at least a part of a first large-diameter portion open toward the motor unit overlaps the inner passage. This can increase a flow rate in the venturi tube, such that the liquid refrigerant can be discharged more quickly and effectively.

In one example, the motor unit may include a stator core fixedly fitted to an inner circumferential surface of the casing, and having a plurality of teeth formed on an inner circumferential surface thereof in a circumferential direction with slits interposed therebetween, and stator coils wound around the teeth of the stator core. The venturi tube may at least partially overlap the slit at an upper side of the stator coil. With the configuration, the venturi tube can be disposed at a position with a high flow rate, so as to further increase suction force with respect to the liquid refrigerant.

In another example, the discharge passage may be open toward the motor unit so that at least a part thereof overlaps the slit in the axial direction. The venturi tube may at least partially overlap the discharge passage at an upper side of the stator coil. This can increase a flow rate in the venturi tube, such that the liquid refrigerant can be discharged more quickly and effectively.

According to the invention, the venturi tube may include a first large-diameter portion defining a first open end and facing the motor unit, a second large-diameter portion defining a second open end and opposing the motor unit, and a small-diameter portion communicating the first large-diameter portion and the second large-diameter portion with each other. The second large-diameter portion may be disposed eccentrically with respect to an axial center of the refrigerant discharge tube. A first spacing height from the motor unit to an end of the second large-diameter portion may be lower than or equal to a second spacing height from the motor unit to an inner end of the refrigerant discharge tube. This can reduce flow resistance with respect to the liquid refrigerant passing through the venturi tube, such that the liquid refrigerant can be discharged quickly.

In one example, the venturi tube may include a first large-diameter portion defining a first open end and facing the motor unit, a second large-diameter portion defining a second open end and opposing the motor unit, and a small-diameter portion disposed between the first large-diameter portion and the second large-diameter portion and connected with the liquid refrigerant discharge tube. The second large-diameter portion may be disposed coaxially with the refrigerant discharge tube. This can facilitate manufacturing of the venturi tube and also further increase the flow rate in the venturi tube so as to increase suction force for the liquid refrigerant.

In another example, the first large-diameter portion and the second large-diameter portion may be disposed on different axes. With the configuration, an inlet of the venturi tube can be disposed at a position with a fast flow rate and an outlet of the venturi tube can be disposed adjacent to the refrigerant discharge tube, so that the liquid refrigerant can be discharged more quickly.

In another example, the first large-diameter portion and the second large-diameter portion may be disposed coaxially with each other. The refrigerant discharge tube may be disposed eccentrically with respect to an axial center of the rotating shaft. With the configuration, the venturi tube and the refrigerant discharge tube can be disposed at a position with a high flow rate, so as to further increase the suction force with respect to the liquid refrigerant.

In one example, the discharge passage may be open toward a discharge space between the motor unit and the compression unit. The second end of the liquid refrigerant discharge tube may be located in the discharge space. This can allow liquid refrigerant stagnating in the discharge space to be quickly discharged and secure an appropriate amount of oil in the inner space of the casing.

In another example, the discharge passage may be provided by at least one along a circumferential direction. The second end of the liquid refrigerant discharge tube may be spaced apart from the discharge passage in the circumferential direction. With the configuration, the liquid refrigerant can be more effectively discharged as an inlet of the liquid refrigerant discharge tube is disposed at a portion where the liquid refrigerant stagnates the most.

In one example, a flow path guide may be disposed in the discharge space between the motor unit and the compression unit to divide the discharge space into an inner space and an outer space. At least one discharge through hole defining the discharge passage and communicating with the inner space may be formed through the flow path guide. The second end of the liquid refrigerant discharge tube may be spaced apart from the discharge through hole in the circumferential direction. With the configuration, the liquid refrigerant can be more effectively discharged as an inlet of the liquid refrigerant discharge tube is disposed at a portion where the liquid refrigerant stagnates the most.

Also, in order to achieve those aspects of the subject matter disclosed herein, there is provided an air conditioner that may include a compressor, a condenser, an expander, and an evaporator. Here, the compressor may be configured as the scroll compressor described above. This can suppress a large amount of liquid refrigerant from stagnating in the compressor when the compressor is initially started, thereby preventing friction loss and wear between members due to a shortage of oil in the compressor.

Hereinafter, a scroll compressor and an air conditioner having the same according to the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, a description of some components may be omitted to clarify features of the present disclosure.

In addition, the term "upper side" used in the following description refers to a direction away from the support surface for supporting a scroll compressor according to an implementation of the present disclosure, that is, a direction toward a motor unit when viewed based on the motor unit and a compression unit. The term "lower side" refers to a direction toward the support surface, that is, a direction toward the compression unit when viewed based on the motor unit and the compression unit.

The term "axial direction" used in the following description refers to a lengthwise (longitudinal) direction of a rotating shaft. The "axial direction" may be understood as an up and down (or vertical) direction. The term "radial direction" refers to a direction that intersects the rotating shaft.

In addition, a description will be given of a bottom-compression type scroll compressor in which a motor unit and a compression unit are arranged vertically in an axial direction and the compression unit is located below the motor unit.

In addition, a description will be given of a bottom-compression high-pressure type scroll compressor in which a refrigerant suction tube defining a suction passage is directly connected to the compression unit and communicates with an inner space of a casing.

<FIG> is a diagram illustrating a refrigeration cycle apparatus to which a bottom-compression type scroll compressor in accordance with one implementation of the present disclosure is applied.

Referring to <FIG>, a refrigeration cycle apparatus to which the scroll compressor according to the implementation is applied may be configured such that a compressor <NUM>, a condenser <NUM>, an expander <NUM>, and an evaporator <NUM> define a closed loop. The condenser <NUM>, the expander <NUM>, and the evaporator <NUM> may be sequentially connected to a discharge side of the compressor <NUM> and a discharge side of the evaporator <NUM> may be connected to a suction side of the compressor <NUM>.

Accordingly, refrigerant compressed in the compressor <NUM> may be discharged toward the condenser <NUM>, and then sucked back into the compressor <NUM> sequentially through the expander <NUM> and the evaporator <NUM>. The series of processes may be repeatedly carried out.

<FIG> is a longitudinal sectional view of a bottom-compression type scroll compressor in accordance with an implementation, <FIG> is an enlarged sectional view of a surrounding of a liquid refrigerant discharge unit in <FIG>, and <FIG> is a horizontal sectional view illustrating an installation position of the liquid refrigerant discharge unit in <FIG>.

Referring to <FIG>, a high-pressure and bottom-compression type scroll compressor (hereinafter, referred to as a scroll compressor) according to an implementation may include a driving motor <NUM> constituting a motor unit disposed in an upper portion of a casing <NUM>, and a main frame <NUM>, a fixed scroll <NUM>, an orbiting scroll <NUM>, and a discharge cover <NUM> sequentially disposed below the driving motor <NUM>. In general, the driving motor <NUM> may constitute a motor unit, and the main frame <NUM>, the fixed scroll <NUM>, the orbiting scroll <NUM>, and the discharge cover <NUM> may constitute a compression unit.

The motor unit may be coupled to an upper end of a rotating shaft <NUM> to be explained later, and the compression unit may be coupled to a lower end of the rotating shaft <NUM>. Accordingly, the compressor may have the bottom-compression type structure described above, and the compression unit may be connected to the motor unit by the rotating shaft <NUM> to be operated by a rotational force of the motor unit.

Referring to <FIG>, the casing <NUM> according to the implementation may include a cylindrical shell <NUM>, an upper shell <NUM>, and a lower shell <NUM>. The cylindrical shell <NUM> may be formed in a cylindrical shape with upper and lower ends open. The upper shell <NUM> may be coupled to cover the opened upper end of the cylindrical shell <NUM>. The lower shell <NUM> may be coupled to cover the opened lower end of the cylindrical shell <NUM>. Accordingly, the inner space 110a of the casing <NUM> may be sealed. The sealed inner space 110a of the casing <NUM> may be divided into a lower space S1 and an upper space S2 based on the driving motor <NUM>.

The lower space S1 may be a space defined below the driving motor <NUM>. The lower space S1 may be further divided into an oil storage space S11 and a discharge space S12 with the compression unit therebetween.

The oil storage space S11 may be a space defined below the compression unit to store oil or mixed oil in which liquid refrigerant is mixed. The discharge space S12 may be a space defined between an upper surface of the compression unit and a lower surface of the driving motor <NUM>. Refrigerant compressed in the compression unit or mixed refrigerant in which oil is contained may be discharged into the discharge space S12.

The upper space S2 may be a space defined above the driving motor <NUM> to form an oil separating space in which oil is separated from refrigerant discharged from the compression unit. The upper space S2 may communicate with the refrigerant discharge tube.

The driving motor <NUM> and the main frame <NUM> may be fixedly inserted into the cylindrical shell <NUM>. An outer circumferential surface of the driving motor <NUM> and an outer circumferential surface of the main frame <NUM> may be respectively provided with an oil return passages Po1 and Po2 each spaced apart from an inner circumferential surface of the cylindrical shell <NUM> by a predetermined distance. This will be described again later together with the oil return passage.

A refrigerant suction tube <NUM> may be coupled through a side surface of the cylindrical shell <NUM>. Accordingly, the refrigerant suction tube <NUM> may be coupled through the cylindrical shell <NUM> forming the casing <NUM> in a radial direction.

The refrigerant suction tube <NUM> may be formed in an L-like shape. One end of the refrigerant suction tube <NUM> may be inserted through the cylindrical shell <NUM> to directly communicate with a suction port <NUM> of the fixed scroll <NUM>, which configures the compression unit. Accordingly, refrigerant can be introduced into a compression chamber V through the refrigerant suction tube <NUM>.

Another end of the refrigerant suction tube <NUM> may be connected to an accumulator <NUM> which defines a suction passage outside the cylindrical shell <NUM>. The accumulator <NUM> may be connected to an outlet side of the evaporator <NUM> through a refrigerant tube. Accordingly, while refrigerant flows from the evaporator <NUM> to the accumulator <NUM>, liquid refrigerant may be separated in the accumulator <NUM>, and only gaseous refrigerant may be directly introduced into the compression chamber V through the refrigerant suction tube <NUM>.

A terminal bracket (not shown) may be coupled to an upper portion of the cylindrical shell <NUM> or the upper shell <NUM>, and a terminal (not shown) for transmitting external power to the driving motor <NUM> may be coupled through the terminal bracket.

An inner end 116a of the refrigerant discharge tube <NUM> may be coupled through an upper portion of the upper shell <NUM> to communicate with the inner space 110a of the casing <NUM>, specifically, the upper space S2 defined above the driving motor <NUM>.

The refrigerant discharge tube <NUM> may correspond to a passage through which compressed refrigerant discharged from the compression unit to the inner space 110a of the casing <NUM> is externally discharged toward the condenser <NUM>. The refrigerant discharge tube <NUM> may be disposed coaxially with the rotating shaft <NUM> to be described later. Accordingly, a venturi tube <NUM> to be described later disposed in parallel with the refrigerant discharge tube <NUM> may be eccentrically disposed with respect to an axial center of the rotating shaft <NUM>.

The refrigerant discharge tube <NUM> may be provided therein with an oil separator (not shown) for separating oil from refrigerant discharged from the compressor <NUM> to the condenser <NUM>, or a check valve (not shown) for suppressing refrigerant discharged from the compressor <NUM> from flowing back into the compressor <NUM>.

One end portion of an oil circulation tube (not illustrated) may be coupled through a lower end portion of the lower shell <NUM>. Both ends of the oil circulation tube may be open, and another end portion of the oil circulation tube may be coupled through the refrigerant suction tube <NUM>. An oil circulation valve (not illustrated) may be installed in a middle portion of the oil circulation tube.

The oil circulation valve may be open or closed according to an amount of oil stored in the oil storage space S11 or according to a set condition. For example, the oil circulation valve may be open to circulate oil stored in the oil storage space to the compression unit through the suction refrigerant tube at the beginning of the operation of the compressor, while being closed to prevent an excessive outflow of oil within the compressor during a normal operation.

Hereinafter, a driving motor constituting the motor unit will be described.

Referring to <FIG>, the driving motor <NUM> according to the implementation may include a stator <NUM> and a rotor <NUM>. The stator <NUM> may be fixed onto the inner circumferential surface of the cylindrical shell <NUM>, and the rotor <NUM> may be rotatably disposed in the stator <NUM>.

The stator <NUM> may include a stator core <NUM> and a stator coil <NUM>.

The stator core <NUM> may be formed in an annular shape or a hollow cylindrical shape and may be shrink-fitted onto the inner circumferential surface of the cylindrical shell <NUM>.

A rotor accommodating portion 1211a may be formed in a circular shape through a central portion of the stator core <NUM> such that the rotor <NUM> can be rotatably inserted therein. A plurality of stator-side return grooves 1211b may be recessed or cut out in a D-cut shape at an outer circumferential surface of the stator core <NUM> along the axial direction and disposed at preset distances along a circumferential direction.

A plurality of teeth 1211c and slots 1211d may be alternately formed on an inner circumferential surface of the rotor accommodating portion 1211a in the circumferential direction, and the stator coil <NUM> may be wound on each tooth 1211c by passing through the slots 1211d at both sides of the tooth 1211c.

Each slot (precisely, a space between adjacent stator coils in the circumferential direction) 1211d may define an inner passage 120a, and a gap passage 120b may be defined between an inner circumferential surface of the stator core <NUM> and an outer circumferential surface of the rotor core <NUM>. Each of the oil return grooves 1211b may define an outer passage 120c. The inner passages 120a and the gap passage 120b may define a passage through which refrigerant discharged from the compression unit moves to the upper space S2, and the outer passages 120c may define a first oil return passage Po1 through which oil separated in the upper space S2 is returned to the oil storage space S11.

The stator coil <NUM> may be wound around the stator core <NUM> and may be electrically connected to an external power source through a terminal (not illustrated) that is coupled through the casing <NUM>. An insulator <NUM>, which is an insulating member, may be inserted between the stator core <NUM> and the stator coil <NUM>.

The insulator <NUM> may be provided at an outer circumferential side and an inner circumferential side of the stator coil <NUM> to accommodate a bundle of the stator coil <NUM> in the radial direction, and may extend to both sides in the axial direction of the stator core <NUM>.

The rotor <NUM> may include a rotor core <NUM> and permanent magnets <NUM>.

The rotor core <NUM> may be formed in a cylindrical shape to be accommodated in the rotor accommodating portion 1211a defined in the central portion of the stator core <NUM>.

Specifically, the rotor core <NUM> may be rotatably inserted into the rotor accommodating portion 1211a of the stator core <NUM> with a predetermined gap 120a therebetween. The permanent magnets <NUM> may be embedded in the rotor core <NUM> at preset intervals along the circumferential direction.

A balance weight <NUM> may be coupled to a lower end of the rotor core <NUM>. Alternatively, the balance weight <NUM> may be coupled to a main shaft portion <NUM> of the rotating shaft <NUM> to be described later. This implementation will be described based on an example in which the balance weight <NUM> is coupled to the rotating shaft <NUM>. The balance weight <NUM> may be disposed on each of a lower end side and an upper end side of the rotor, and the two balance weights <NUM> may be installed symmetrically to each other.

The rotating shaft <NUM> may be coupled to the center of the stator core <NUM>. An upper end portion of the rotating shaft <NUM> may be press-fitted to the rotor <NUM>, and a lower end portion of the rotating shaft <NUM> may be rotatably inserted into the main frame <NUM> to be supported in the radial direction.

The main frame <NUM> may be provided with a main bearing <NUM> configured as a bush bearing to support the lower end portion of the rotating shaft <NUM>. Accordingly, a portion, which is inserted into the main frame <NUM>, of the lower end portion of the rotating shaft <NUM> may smoothly rotate inside the main frame <NUM>.

The rotating shaft <NUM> may transfer a rotational force of the driving motor <NUM> to an orbiting scroll <NUM> constituting the compression unit. Accordingly, the orbiting scroll <NUM> eccentrically coupled to the rotating shaft <NUM> may perform an orbiting motion with respect to the fixed scroll <NUM>.

Referring to <FIG>, the rotating shaft <NUM> according to the implementation may include a main shaft portion <NUM>, a first bearing portion <NUM>, a second bearing portion <NUM>, and an eccentric portion <NUM>.

The main shaft portion <NUM> may be an upper portion of the rotating shaft <NUM> and may be formed in a cylindrical shape. The main shaft portion <NUM> may be partially press-fitted into the stator core <NUM>.

The first bearing portion <NUM> may be a portion extending from a lower end of the main shaft portion <NUM>. The first bearing portion <NUM> may be inserted into a main bearing hole <NUM> of the main frame <NUM> so as to be supported in the radial direction.

The second bearing portion <NUM> may be a lower portion of the rotating shaft <NUM>. The second bearing portion <NUM> may be inserted into a sub bearing hole 143a of a fixed scroll <NUM> to be described later so as to be supported in the radial direction. A central axis of the second bearing portion <NUM> and a central axis of the first bearing portion <NUM> may be aligned on the same line. That is, the first bearing portion <NUM> and the second bearing portion <NUM> may have the same central axis.

The eccentric portion <NUM> may be formed between a lower end of the first bearing portion <NUM> and an upper end of the second bearing portion <NUM>. The eccentric portion <NUM> may be inserted into a rotating shaft coupling portion <NUM> of the orbiting scroll <NUM> to be described later.

The eccentric portion <NUM> may be eccentric with respect to the first bearing portion <NUM> or the second bearing portion <NUM> in the radial direction. That is, a central axis of the eccentric portion <NUM> may be eccentric with respect to the central axis of the first bearing portion <NUM> and the central axis of the second bearing portion <NUM>. Accordingly, when the rotating shaft <NUM> rotates, the orbiting scroll <NUM> may perform an orbiting motion with respect to the fixed scroll <NUM>.

On the other hand, an oil supply passage <NUM> for supplying oil to the first bearing portion <NUM>, the second bearing portion <NUM>, and the eccentric portion <NUM> may be formed in a hollow shape in the rotating shaft <NUM>. The oil supply passage <NUM> may include an inner oil passage <NUM> defined in the rotating shaft <NUM> along the axial direction.

As the compression unit is located below the motor unit <NUM>, the inner oil passage <NUM> may be formed in a grooving manner from the lower end of the rotating shaft <NUM> approximately to a lower end or a middle height of the stator <NUM> or up to a position higher than an upper end of the first bearing portion <NUM>. Although not illustrated, the inner oil passage <NUM> may alternatively be formed through the rotating shaft <NUM> in the axial direction.

An oil pickup <NUM> for pumping up oil filled in the oil storage space S11 may be coupled to the lower end of the rotating shaft <NUM>, namely, a lower end of the second bearing portion <NUM>. The oil pickup <NUM> may include an oil supply tube <NUM> inserted into the inner oil passage <NUM> of the rotating shaft <NUM>, and a blocking member <NUM> accommodating the oil supply tube <NUM> to block an introduction of foreign materials. The oil supply tube <NUM> may extend downward through the discharge cover <NUM> to be immersed in the oil filled in the oil storage space S11.

The rotating shaft <NUM> may be provided with a plurality of oil supply holes communicating with the inner oil passage <NUM> to guide oil moving upward along the inner oil passage <NUM> toward the first and second bearing portions <NUM> and <NUM> and the eccentric portion <NUM>.

Hereinafter, the compression unit will be described.

Referring to <FIG>, the compression unit according to the implementation may include a main frame <NUM>, a fixed scroll <NUM>, an orbiting scroll <NUM>, a discharge cover <NUM>, and a flow path guide <NUM>.

The main frame <NUM> may include a frame end plate <NUM>, a frame side wall <NUM>, and a main bearing portion <NUM>.

The frame end plate <NUM> may be formed in an annular shape and installed below the driving motor <NUM>. The frame side wall <NUM> may extend in a cylindrical shape from an edge of a lower surface of the frame end plate <NUM>, and an outer circumferential surface of the frame side wall <NUM> may be fixed to the inner circumferential surface of the cylindrical shell <NUM> in a shrink-fitting or welding manner. Accordingly, the oil storage space S11 and the discharge space S12 constituting the lower space S1 of the casing <NUM> may be separated from each other by the frame end plate <NUM> and the frame side wall <NUM>.

A frame discharge hole (hereinafter, a second discharge hole) <NUM> forming a part of a discharge passage may be formed through the frame side wall <NUM> in the axial direction. The second discharge hole <NUM> may be formed to correspond to a scroll discharge hole (first discharge hole) <NUM> of the fixed scroll <NUM> to be described later, to define a refrigerant discharge passage (no reference numeral given) together with the first discharge hole <NUM>.

The second discharge hole <NUM> may be elongated in the circumferential direction, or may be provided in plurality disposed at preset intervals along the circumferential direction. Accordingly, the second discharge hole <NUM> can secure a volume of a compression chamber relative to the same diameter of the main frame <NUM> by maintaining a minimum radial width with securing a discharge area. This may equally be applied to the first discharge hole <NUM> that is formed in the fixed scroll <NUM> to define a part of the discharge passage.

A discharge guide groove <NUM> to accommodate the plurality of second discharge holes 132a may be formed in an upper end of the second discharge hole <NUM>, namely, an upper surface of the frame end plate <NUM>. At least one discharge guide groove <NUM> may be formed according to positions of the second discharge holes <NUM>. For example, when the second discharge holes <NUM> form three groups, the number of discharge guide grooves <NUM> may be three to accommodate the three groups of second discharge holes <NUM>, respectively. The three discharge guide grooves <NUM> may be located on the same line in the circumferential direction.

The discharge guide groove <NUM> may be formed wider than the second discharge hole <NUM>. For example, the second discharge hole <NUM> may be formed on the same line in the circumferential direction together with a first oil return groove <NUM> to be described later. Therefore, when a flow path guide <NUM> to be described later is provided, the second discharge hole <NUM> having a small cross-sectional area may be difficult to be located at an inner side of the flow path guide <NUM>. With this reason, the discharge guide groove <NUM> may be formed at an end portion of the second discharge hole <NUM> while an inner circumferential side of the discharge guide groove <NUM> extends radially up to the inner side of the flow path guide <NUM>.

Accordingly, the second discharge hole <NUM> can be located adjacent to the outer circumferential surface of the main frame <NUM> by reducing an inner diameter of the second discharge hole <NUM>, and simultaneously can be prevented from being located at an outer side of the flow path guide <NUM>, namely, adjacent to the outer circumferential surface of the stator <NUM>.

A frame oil return groove (hereinafter, first oil return groove) <NUM> that defines a part of a second oil return passage Po2 may be formed axially through an outer circumferential surface of the frame end plate <NUM> and an outer circumferential surface of the frame side wall <NUM> that define the outer circumferential surface of the main frame <NUM>. The first oil return groove <NUM> may be provided by only one or may be provided in plurality disposed in the outer circumferential surface of the main frame <NUM> at preset intervals in the circumferential direction. Accordingly, the discharge space S12 of the casing <NUM> can communicate with the oil storage space S11 of the casing <NUM> through the first oil return groove <NUM>.

The first oil return groove <NUM> may be formed to correspond to a scroll oil return groove (hereinafter, second oil return groove) <NUM> of the fixed scroll <NUM>, which will be described later, and define the second oil return passage together with the second oil return groove <NUM> of the fixed scroll <NUM>.

The main bearing portion <NUM> may protrude upward from an upper surface of a central portion of the frame end plate <NUM> toward the driving motor <NUM>. The main bearing portion <NUM> may be provided with a main bearing hole <NUM> formed therethrough in a cylindrical shape along the axial direction. The first bearing portion <NUM> of the rotating shaft <NUM> may be inserted into the main bearing hole <NUM> to be supported in the radial direction.

Hereinafter, the fixed scroll will be described.

Referring to <FIG>, the fixed scroll <NUM> according to the implementation may include a fixed end plate <NUM>, a fixed side wall <NUM>, a sub bearing portion <NUM>, and a fixed wrap <NUM>.

The fixed end plate <NUM> may be formed in a disk shape having a plurality of concave portions on an outer circumferential surface thereof, and a sub bearing hole <NUM> defining the sub bearing portion <NUM> to be described later may be formed through a center of the fixed end plate <NUM> in the vertical direction. Discharge ports <NUM> and <NUM> may be formed around the sub bearing hole <NUM>. The discharge ports <NUM> and <NUM> may communicate with a discharge pressure chamber Vd so that compressed refrigerant is moved into the discharge space S12 of the discharge cover <NUM> to be explained later.

Although not shown, only one discharge port may be provided to communicate with both of a first compression chamber V1 and a second compression chamber V2 to be described later. In the implementation, however, a first discharge port (no reference numeral given) may communicate with the first compression chamber V1 and a second discharge port (no reference numeral given) may communicate with the second compression chamber V2. Accordingly, refrigerant compressed in the first compression chamber V1 and refrigerant compressed in the second compression chamber V2 may be independently discharged through the different discharge ports.

The fixed side wall <NUM> may extend in an annular shape from an edge of an upper surface of the fixed end plate <NUM> in the vertical direction. The fixed side wall <NUM> may be coupled to face the frame side wall <NUM> of the main frame <NUM> in the vertical direction.

A scroll discharge hole (hereinafter, first discharge hole) <NUM> may be formed through the fixed side wall <NUM> in the axial direction. The first discharge hole <NUM> may be elongated in the circumferential direction, or may be provided in plurality disposed at preset intervals along the circumferential direction. Accordingly, the first discharge hole <NUM> can secure a volume of a compression chamber relative to the same diameter of the fixed scroll <NUM> by maintaining a minimum radial width with securing a discharge area.

The first discharge hole <NUM> may communicate with the second discharge hole <NUM> in a state in which the fixed scroll <NUM> is coupled to the cylindrical shell <NUM>. Accordingly, the first discharge hole <NUM> can define a refrigerant discharge passage together with the second discharge hole <NUM>.

A second oil return groove <NUM> may be formed in an outer circumferential surface of the fixed side wall <NUM>. The second oil return groove <NUM> may communicate with the first oil return groove <NUM> provided at the main frame <NUM> to guide oil returned along the first oil return groove <NUM> to the oil storage space S11. Accordingly, the first oil return groove <NUM> and the second oil return groove <NUM> may define the second oil return passage Po2 together with an oil return groove <NUM> of the discharge cover <NUM> to be described later.

The fixed side wall <NUM> may be provided with a suction port <NUM> formed through the fixed side wall <NUM> in the radial direction. An end portion of the refrigerant suction tube <NUM> inserted through the cylindrical shell <NUM> may be inserted into the suction port <NUM>. Accordingly, refrigerant can be introduced into a compression chamber V through the refrigerant suction tube <NUM>.

The sub bearing portion <NUM> may extend in the axial direction from a central portion of the fixed end plate <NUM> toward the discharge cover <NUM>. A sub bearing hole <NUM> having a cylindrical shape may be formed through a center of the sub bearing portion <NUM> in the axial direction, and the second bearing portion <NUM> of the rotating shaft <NUM> may be inserted into the sub bearing hole <NUM> to be supported in the radial direction. Therefore, the lower end (or the second bearing portion) of the rotating shaft <NUM> can be radially supported by being inserted into the sub bearing portion <NUM> of the fixed scroll <NUM>, and the eccentric portion <NUM> of the rotating shaft <NUM> can be supported in the axial direction by an upper surface of the fixed end plate <NUM> defining the surrounding of the sub bearing portion <NUM>.

A fixed wrap <NUM> may extend from the upper surface of the fixed end plate <NUM> toward the orbiting scroll <NUM> in the axial direction. The fixed wrap <NUM> may be engaged with an orbiting wrap <NUM> to be described later to define the compression chamber V. The fixed wrap <NUM> will be described later together with the orbiting wrap <NUM>.

Hereinafter, the orbiting scroll will be described.

Referring to <FIG>, the orbiting scroll <NUM> according to the implementation may include an orbiting end plate <NUM>, an orbiting wrap <NUM>, and a rotating shaft coupling portion <NUM>.

The orbiting end plate <NUM> may be formed in a disk shape and accommodated in the main frame <NUM>. An upper surface of the orbiting end plate <NUM> may be supported in the axial direction by the main frame <NUM> with interposing a back pressure sealing member (no reference numeral given) therebetween.

The orbiting wrap <NUM> may extend from a lower surface of the orbiting end plate <NUM> toward the fixed scroll <NUM>. The orbiting wrap <NUM> may be engaged with the fixed wrap <NUM> to define the compression chamber V.

The orbiting wrap <NUM> may be formed in an involute shape together with the fixed wrap <NUM>. However, the orbiting wrap <NUM> and the fixed wrap <NUM> may be formed in various shapes other than the involute shape.

For example, the orbiting wrap <NUM> may be formed in a substantially elliptical shape in which a plurality of arcs having different diameters and origins are connected and the outermost curve may have a major axis and a minor axis. The fixed wrap <NUM> may also be formed in a similar manner.

An inner end portion of the orbiting wrap <NUM> may be formed at a central portion of the orbiting end plate <NUM>, and the rotating shaft coupling portion <NUM> may be formed through the central portion of the orbiting end plate <NUM> in the axial direction.

The eccentric portion <NUM> of the rotating shaft <NUM> may be rotatably inserted into the rotating shaft coupling portion <NUM>. An outer circumferential part of the rotating shaft coupling portion <NUM> may be connected to the orbiting wrap <NUM> to define the compression chamber V together with the fixed wrap <NUM> during a compression process.

The rotating shaft coupling portion <NUM> may be formed at a height at which it overlaps the orbiting wrap <NUM> on the same plane. That is, the rotating shaft coupling portion <NUM> may be disposed at a height at which the eccentric portion <NUM> of the rotating shaft <NUM> overlaps the orbiting wrap <NUM> on the same plane. Accordingly, repulsive force and compressive force of refrigerant can cancel each other while being applied to the same plane based on the orbiting end plate <NUM>, and thus inclination of the orbiting scroll <NUM> due to interaction between the compressive force and the repulsive force can be suppressed.

On the other hand, the compression chamber V may be formed in a space defined by the fixed end plate <NUM>, the fixed wrap <NUM>, the orbiting end plate <NUM>, and the orbiting wrap <NUM>. The compression chamber V may include a first compression chamber V1 defined between an inner surface of the fixed wrap <NUM> and an outer surface of the orbiting wrap <NUM>, and a second compression chamber V2 defined between an outer surface of the fixed wrap <NUM> and an inner surface of the orbiting wrap <NUM>.

Hereinafter, the discharge cover will be described.

Referring to <FIG>, the discharge cover <NUM> may include a cover housing portion <NUM> and a cover flange portion <NUM>.

The cover housing portion <NUM> may have a cover space <NUM> defining the discharge space S3 together with the lower surface of the fixed scroll <NUM>.

An outer circumferential surface of the cover housing portion <NUM> may come in close contact with the inner circumferential surface of the casing <NUM>. Here, a portion of the cover housing portion <NUM> may be spaced apart from the casing <NUM> in the circumferential direction to define an oil return groove <NUM>. The oil return groove <NUM> may define a third oil return groove together with an oil return groove <NUM> formed in an outer circumferential surface of the cover flange portion <NUM>. The third oil return groove <NUM> of the discharge cover <NUM> may define the second oil return passage Po2 together with the first oil return groove of the main frame <NUM> and the second oil return groove of the fixed scroll <NUM>.

At least one discharge hole accommodating groove <NUM> may be formed in an inner circumferential surface of the cover housing portion <NUM> in the circumferential direction. The discharge hole accommodating groove <NUM> may be recessed outward in the radial direction, and the first discharge hole <NUM> of the fixed scroll <NUM> defining the discharge passage may be located inside the discharge hole accommodating groove <NUM>. Accordingly, an inner surface of the cover housing portion <NUM> excluding the discharge hole accommodating groove <NUM> may be brought into close contact with an outer circumferential surface of the fixed scroll <NUM>, namely, an outer circumferential surface of the fixed end plate <NUM> so as to configure a type of sealing part.

An entire circumferential angle of the discharge hole accommodating groove <NUM> may be formed to be smaller than or equal to an entire circumferential angle with respect to an inner circumferential surface of the discharge space S3 except for the discharge hole accommodating groove <NUM>. In this manner, the inner circumferential surface of the discharge space S3 except for the discharge hole accommodating groove <NUM> can secure not only a sufficient sealing area but also a circumferential length for forming the cover flange portion <NUM>.

The cover flange portion <NUM> may extend radially from a portion defining the sealing part, namely, an outer circumferential surface of a portion, excluding the discharge hole accommodating groove <NUM>, of an upper surface of the cover housing portion <NUM>.

The cover flange portion <NUM> may be provided with coupling holes (no reference numeral given) for coupling the discharge cover <NUM> to the fixed scroll <NUM> with bolts, and a plurality of oil return grooves <NUM> may be formed in a radially recessed manner at preset intervals along the circumferential direction between the adjacent coupling holes. The oil return groove <NUM> may define the third oil return groove together with the oil return groove <NUM> of the cover housing portion <NUM>.

Hereinafter, the flow path guide will be described.

Referring to <FIG> and <FIG>, the flow path guide <NUM> according to this implementation may be installed between the motor unit and the compression unit, for example, in the discharge space S12. Specifically, the flow path guide <NUM> may be disposed at the upper end of the main frame <NUM> that faces the lower end of the driving motor <NUM>.

The flow path guide <NUM> may divide the discharge space S12 into a refrigerant discharge flow path and an oil return flow path. Accordingly, refrigerant discharged from the compression unit to the discharge space S12 may move to the upper space S2 through the inner passages 120a and the gap passage 120b. Oil separated from the refrigerant in the upper space S2 may be returned to the oil storage space S11 through the outer passages 120c.

The flow path guide <NUM> may be formed in a single annular shape or may be formed in a shape defined by a plurality of arcuate parts. Hereinafter, an example in which the flow path guide <NUM> is formed in a single annular shape will be mainly described, but even when it is formed in a shape defined by a plurality of arcuate parts, the basic configuration for separating refrigerant and oil and operating effects thereof may be similar.

For example, the flow path guide <NUM> may include a bottom portion <NUM>, an outer wall <NUM>, and an inner wall <NUM>.

The bottom portion <NUM> may be formed in an annular shape and fixed to the upper surface of the main frame <NUM>. A discharge passage cover portion <NUM> may radially extend from an outer circumferential surface of the bottom portion <NUM>. A discharge through hole <NUM> may be formed through the discharge passage cover portion <NUM> to overlap the discharge guide groove <NUM> of the main frame <NUM>.

The outer wall <NUM> may extend from a substantially outer circumferential surface of the bottom portion <NUM> toward the insulator <NUM>. The outer wall <NUM> may be fitted to an inner side or outer side of the insulator <NUM> to overlap the insulator <NUM>. The outer wall <NUM> may be formed in an annular shape extending in the circumferential direction or may be formed in an arcuate shape.

When the outer wall <NUM> is formed in an annular shape, a diameter of the outer wall <NUM> may be smaller or larger than a diameter of the insulator <NUM> or an upper end of the outer wall <NUM> may be spaced apart from a lower end of the insulator <NUM>. Accordingly, a gap may be formed between the outer wall <NUM> and the insulator <NUM>, such that refrigerant (liquid refrigerant) discharged to the inner side of the outer wall <NUM> can move toward an outer space S12b in which a second end 192b of a liquid refrigerant discharge tube <NUM> to be explained later is located. This can allow the liquid refrigerant to be rapidly discharged to the outside of the compressor through a liquid refrigerant discharge unit <NUM>.

Although not illustrated, when a communication path such as the gap is not formed between the annular outer wall <NUM> and the insulator <NUM>, a communication groove (not illustrated) through which an inner space S12a and the outer space S12b communicate with each other may be formed in the bottom portion <NUM> or the main frame <NUM> facing the bottom portion <NUM>.

The inner wall <NUM> may extend from a substantially inner circumferential surface of the bottom portion <NUM> toward the insulator <NUM>. The inner wall <NUM> may extend in the axial direction or may extend by being bent to cover the balance weight <NUM>.

Meanwhile, referring to <FIG>, a liquid refrigerant discharge unit <NUM> for discharging liquid refrigerant stagnated in the inner space 110a of the casing <NUM> to the refrigerant discharge tube <NUM> may be disposed inside the casing <NUM>. The liquid refrigerant discharge unit <NUM> may include a venturi tube <NUM> and a liquid refrigerant discharge tube <NUM> connected to a small-diameter portion <NUM> of the venturi tube <NUM>.

The venturi tube <NUM> may be separately installed between the driving motor <NUM> and the refrigerant discharge tube <NUM> inside the casing <NUM> or may be configured by using the refrigerant discharge tube <NUM>. Hereinafter, a description will be given of an example of installing the venturi tube <NUM> separately which is a first implementation, and an example using the refrigerant discharge tube <NUM> which is a second implementation. The first and second implementations will be described again later.

In the drawings, unexplained reference numeral <NUM> denotes a condenser fan, and <NUM> denotes an evaporator fan.

The scroll compressor according to the implementation of the present disclosure may operate as follows.

That is, when power is applied to the motor unit <NUM>, rotational force may be generated and the rotor <NUM> and the rotating shaft <NUM> may rotate accordingly. As the rotating shaft <NUM> rotates, the orbiting scroll <NUM> eccentrically coupled to the rotating shaft <NUM> may perform an orbiting motion relative to the fixed scroll <NUM> by the Oldham ring <NUM>.

Accordingly, the volume of the compression chamber V may decrease gradually along a suction pressure chamber Vs defined at an outer side of the compression chamber V, an intermediate pressure chamber Vm continuously formed toward a center, and a discharge pressure chamber Vd defined in a central portion.

Then, refrigerant may move to the accumulator <NUM> sequentially via the condenser <NUM>, the expander <NUM>, and the evaporator <NUM> of the refrigeration cycle. The refrigerant may flow toward the suction pressure chamber Vs forming the compression chamber V through the refrigerant suction tube <NUM>.

The refrigerant suctioned into the suction pressure chamber Vs may be compressed while moving to the discharge pressure chamber Vd via the intermediate pressure chamber Vm along a movement trajectory of the compression chamber V. The compressed refrigerant may be discharged from the discharge pressure chamber Vd to the discharge space S12 of the discharge cover <NUM> through the discharge ports <NUM> and <NUM>.

Then, the refrigerant (refrigerant is oil-mixed refrigerant, but in description, mixed refrigerant or refrigerant will all be used) that has been discharged to the discharge space S12 of the discharge cover <NUM> may move to the discharge space S12 defined between the main frame <NUM> and the driving motor <NUM> through the discharge hole accommodating groove <NUM> of the discharge cover <NUM> and the first discharge hole <NUM> of the fixed scroll <NUM>. The mixed refrigerant may pass through the driving motor <NUM> to move to the upper space S2 of the casing <NUM> defined above the driving motor <NUM>.

The mixed refrigerant moved to the upper space S2 may be separated into refrigerant and oil in the upper space S2. The refrigerant (or some mixed refrigerant from which oil is not separated) may be discharged out of the casing <NUM> through the refrigerant discharge tube <NUM> so as to move to the condenser <NUM> of the refrigeration cycle.

On the other hand, the oil separated from the refrigerant in the upper space S2 (or mixed oil with liquid refrigerant) may move to the lower space S1 along the first oil return passage Po1 between the inner circumferential surface of the casing <NUM> and the stator <NUM>. The oil moved to the lower space S1 may be returned to the oil storage space S11 defined in the lower portion of the compression unit along the second oil return passage Po2 between the inner circumferential surface of the casing <NUM> and the outer circumferential surface of the compression unit.

This oil may thusly be supplied to each bearing surface (not illustrated) through the oil supply passage <NUM>, and partially supplied into the compression chamber V. Oil supplied to bearing surfaces and the compression chamber V may be discharged to the discharge cover <NUM> together with refrigerant and then returned. This series of processes may be repeatedly performed.

At this time, as the flow path guide <NUM> by which the refrigerant discharge passage and the oil return passage are separated is disposed in a space, namely, the discharge space S12 defined between the lower end of the driving motor <NUM> and the upper end of the main frame <NUM>, the refrigerant that is discharged from the compression unit and moves toward the upper space S2 can be suppressed from being mixed with the oil moving from the upper space S2 to the lower space S1.

Meanwhile, as described above, when the compressor is started, liquid refrigerant may excessively stagnate in the inner space of the casing. This problem may occur more severely due to a delay of a point of time at which an internal temperature of the compressor reaches an oil superheat when an outdoor unit including a large compressor, such as an air conditioner, is exposed to a low-temperature stop state for a long time.

When the liquid refrigerant excessively stagnates in the inner space of the compressor, viscosity of oil mixed in the liquid refrigerant may be lowered, which may cause friction loss and wear on the compression unit and the bearing surfaces during the initial operation of the compressor. In addition, when the internal temperature of the compressor reaches the oil superheat, a large amount of liquid refrigerant may be vaporized and flow out together with oil to the outside of the compressor, which may further aggravate the friction loss and wear on the compression unit and the bearing surfaces.

Accordingly, in this implementation, a liquid refrigerant discharging device for discharging liquid refrigerant from the inner space of the casing may be installed so that the liquid refrigerant does not stagnate inside the compressor. The liquid refrigerant discharging device according to this implementation may be installed in the inner space of the casing. Hereinafter, the liquid refrigerant discharging device will be defined as the liquid refrigerant discharge unit <NUM> and a description thereof will be given.

Referring to <FIG> and <FIG> again, the liquid refrigerant discharge unit <NUM> according to the implementation may include a venturi tube <NUM> and a liquid refrigerant discharge tube <NUM>.

The venturi tube <NUM> may be disposed between the upper end of the driving motor <NUM> and the refrigerant discharge tube <NUM>, to be in parallel to an axial center O of the rotating shaft <NUM> at a position eccentric from the axial center of the rotating shaft <NUM> by a preset distance. For example, a lower end of the venturi tube <NUM> facing the drive motor <NUM> may be spaced apart from the upper end of the stator coil <NUM> constituting a part of the driving motor <NUM> by a preset distance, and an upper end of the venturi tube <NUM> (linearly or obliquely) facing the refrigerant discharge tube <NUM> may be spaced apart from the inner circumferential surface of the upper shell <NUM> by a preset distance.

Specifically, the venturi tube <NUM> may be formed in a hollow shape with both ends open. For example, the venturi tube <NUM> may include a first large-diameter portion <NUM> and a second large-diameter portion <NUM> formed at both ends thereof to define a first open end and a second open end, respectively, and at least one small-diameter portion <NUM> formed between the first large-diameter portion <NUM> and the second large-diameter portion <NUM>. In this implementation, an example in which one small-diameter portion <NUM> is provided will be mainly described. Also, for convenience of explanation, the first large-diameter portion <NUM> may be defined as an inlet of the venturi tube <NUM> open toward the driving motor <NUM> and the second large-diameter portion <NUM> may be defined as an outlet of the venturi tube <NUM> open toward the refrigerant discharge tube <NUM>.

A lower end of the first large-diameter portion <NUM> may face the stator coil <NUM> and also may be located at a position where a flow rate of refrigerant is the fastest in the upper space S2 of the casing <NUM>. This can enhance a venturi effect in the venturi tube <NUM>.

In other words, a lower end of the first large-diameter portion <NUM> may at least partially overlap the inner passage 120a between the adjacent stator coils (coil bundles) <NUM> in the driving motor <NUM>, and the lower end of the inner passage 120a may at least partially overlap the discharge through hole <NUM> of the flow path guide <NUM> (or the discharge guide groove of the main frame), which is open toward the discharge space S12 in the compression unit. Since the first large-diameter portion <NUM> overlaps the discharge through hole <NUM> of the flow path guide <NUM> in the axial direction through the inner passage 120a, the first large-diameter portion <NUM> can be located at the position where the flow rate of the refrigerant is the fastest. Accordingly, some of refrigerant flowing through the discharge through hole <NUM> of the flow path guide <NUM> and the inner passage 120a between the stator coils <NUM> can be quickly introduced into the venturi tube <NUM>, thereby enhancing a liquid refrigerant suction effect in the venturi tube <NUM>.

The first large-diameter portion <NUM> may have a circular cross section. However, in some cases, it may have a rectangular or arcuate cross section. For example, when the first large-diameter portion <NUM> is formed in the rectangular shape, the first large-diameter portion <NUM> may be formed to overlap the plurality of slots (more precisely, the inner passages) adjacent to each other. Accordingly, a larger amount of refrigerant can be introduced into the venturi tube <NUM>.

The first large-diameter portion <NUM> may have a cross-sectional area that is larger than or equal to a cross-sectional area of one slot (to be precise, one inner passage) 1211d. With the configuration, the refrigerant flowing toward the upper space S2 through the slots 1211d can be guided not to flow aside the venturi tube <NUM>, thereby increasing an introduction of the refrigerant into the venturi tube <NUM>.

The first large-diameter portion <NUM> may have a cross-sectional area larger than that of the small-diameter portion <NUM> and equal to that of the second large-diameter portion <NUM>. This can facilitate the manufacturing of the venturi tube <NUM>. However, it may not be always necessary that the cross-sectional area of the first large-diameter portion <NUM> is the same as that of the second large-diameter portion <NUM>. For example, the first large-diameter portion <NUM> may have an inner diameter that is larger than an inner diameter of the second large-diameter portion <NUM>. This can allow more refrigerant moving to the upper space S2 to be introduced into the venturi tube <NUM>, so as to increase the flow rate of the refrigerant.

The second large-diameter portion <NUM> may be formed to be symmetrical with the first large-diameter portion <NUM> based on the small-diameter portion <NUM>. This can facilitate the manufacturing of the venturi tube <NUM>. However, it may not be always necessary that the second large-diameter portion <NUM> is symmetrical with the first large-diameter portion <NUM> based on the small-diameter portion <NUM>. For example, the first large-diameter portion <NUM> may be formed to have a rectangular cross-section but the second large-diameter portion <NUM> may be formed to have a circular cross-section to correspond to the refrigerant discharge tube <NUM>. Accordingly, a larger amount of refrigerant can flow into the first large-diameter portion <NUM> while refrigerant passing through the second large-diameter portion <NUM> can flow toward the refrigerant discharge tube <NUM> without leakage (while minimizing leakage).

The second large-diameter portion <NUM> may be formed on the same axis (coaxially) with the small-diameter portion <NUM> and/or the first large-diameter portion <NUM>. This can reduce flow resistance that is caused when the refrigerant having passed through the first large-diameter portion <NUM> and the small-diameter portion <NUM> flows into the second large-diameter portion <NUM> or flows through the second large-diameter portion <NUM>. In this case, an end surface of the second large-diameter portion <NUM> may be cut to be inclined or stepped toward the refrigerant discharge tube <NUM>. Accordingly, the refrigerant passing through the second large-diameter portion <NUM> can flow to the refrigerant discharge tube <NUM> more quickly.

However, it may not be always necessary that the second large-diameter portion <NUM> is formed on the same axis as the first large-diameter portion <NUM> based on the small-diameter portion <NUM>. For example, the second large-diameter portion <NUM> may be in parallel with the first large-diameter portion <NUM>. In this case, the first large-diameter portion <NUM> or the second large-diameter portion <NUM> may be bent or the small-diameter portion <NUM> may be bent. This will be described again later in another implementation.

An upper end of the second large-diameter portion <NUM> may preferably be lower than or equal to an inner end of the refrigerant discharge tube <NUM>. For example, based on the upper end of the driving motor <NUM> (stator core or rotor core), a first spacing height H1 from the upper end of the stator core <NUM> to the upper end (second open end) of the second large-diameter portion <NUM> may be lower than or equal to a second spacing height H2 from the upper end of the stator core <NUM> to the inner end 116a of the refrigerant discharge tube <NUM>. Accordingly, the refrigerant passing through the second large-diameter portion <NUM> can flow to the refrigerant discharge tube <NUM> quickly.

On the other hand, the small-diameter portion <NUM> may have a cross-sectional area that is smaller than the cross-sectional area of the first large-diameter portion <NUM> and/or the second large-diameter portion <NUM>. Both ends of the small-diameter portion <NUM> may be connected to the first large-diameter portion <NUM> and the second large-diameter portion <NUM>, respectively. Here, a connected portion between the small-diameter portion <NUM> and the first large-diameter portion <NUM> and a connected portion between the small-diameter portion <NUM> and the second large-diameter portion <NUM> may preferably be curved to smooth the flow of fluid.

The small-diameter portion <NUM> may communicate with an upper end (first end) 192a of a liquid refrigerant discharge tube <NUM> to be described later. The inner diameter of the small-diameter portion <NUM> may be almost the same as that of the liquid refrigerant discharge tube <NUM>. Accordingly, the liquid refrigerant suctioned into the venturi tube <NUM> through the liquid refrigerant discharge tube <NUM> can be mixed with refrigerant, which flows from the first large-diameter portion <NUM> to the second large-diameter portion <NUM> of the venturi tube <NUM>, and then quickly discharged into the refrigerant discharge tube <NUM>.

The liquid refrigerant discharge tube <NUM> according to this implementation may be configured as a smooth tube having a circular cross section and a single inner diameter. However, in some cases, the liquid refrigerant discharge tube <NUM> may be configured as a tube having a non-circular cross section and a plurality of inner diameters. For example, the liquid refrigerant discharge tube <NUM> may have a rectangular or triangular cross section to correspond to the shape of the oil return groove 1211b of the stator core <NUM>. Here, a first end 192a of the liquid refrigerant discharge tube <NUM> connected to the small-diameter portion <NUM> may have a small inner diameter and a second end 192b as another end may have a large inner diameter.

The first end 192a of the liquid refrigerant discharge tube <NUM> may be connected to the venturi tube <NUM> as described above, and the second end 192b may communicate with the discharge space S12 through the driving motor <NUM>. For example, the first end 192a may be connected to the small-diameter portion <NUM> of the venturi tube <NUM> in the upper space and the second end 192b may communicate with the discharge space S12, more precisely, the outer space through the oil return groove 1911b of the stator core <NUM>. Accordingly, when the liquid refrigerant stagnates up to an upper side of the compression unit, namely, the discharge space S12, the liquid refrigerant can be suctioned into the venturi tube <NUM> through the liquid refrigerant discharge tube <NUM>, move toward the upper space together with refrigerant inside the venturi tube <NUM>, and then flow out of the casing through the refrigerant discharge tube <NUM>.

In some cases, the second end 192b of the liquid refrigerant discharge tube <NUM> may be inserted up to a position where it partially overlaps the compression unit in the axial direction, that is, into the first oil return groove <NUM> of the main frame <NUM> or the second oil return groove <NUM> of the fixed scroll <NUM>. However, in this case, oil returned or stored in the inner space 110a of the casing <NUM> may leak. Therefore, the second end 192b of the liquid refrigerant discharge tube <NUM> may preferably be located as low as possible within a range in which oil returned or stored in the inner space 110a of the casing <NUM> does not leak out.

Although not illustrated in the drawings, the second end 192b of the liquid refrigerant discharge tube <NUM> may be inserted into the upper end of the oil return groove 1911b without passing through the oil return groove 1911b of the stator core <NUM>. In this case, the oil return groove 1911b to which the second end 192b of the liquid refrigerant discharge tube <NUM> is connected may serve as a liquid refrigerant discharge tube.

The second end 192b of the liquid refrigerant discharge tube <NUM> may preferably be located, if possible, at a position where a flow rate of fluid (liquid refrigerant) is the slowest, that is, a position where the liquid refrigerant is likely to stagnate the most. For example, the second end 192b of the liquid refrigerant discharge tube <NUM> may be located furthest from the discharge through hole (or discharge guide groove) <NUM> of the refrigerant. Specifically, when there are a plurality of discharge through holes <NUM>, the second end 192b of the liquid refrigerant discharge tube <NUM> may be disposed between the plurality of discharge through holes <NUM> at a position where it does not overlap the discharge through holes <NUM> in the circumferential direction.

Hereinafter, a description will be given of operating effects of the liquid refrigerant discharge unit according to the implementation of the present disclosure.

That is, as described above, at the initial operation of the compressor <NUM> that is exposed to a low-temperature stop state, a large amount of liquid refrigerant may be introduced into the compression unit together with gas refrigerant and oil, and discharged into the inner space S12a of the discharge space S12 that is located in the inner space 110a of the casing <NUM>, namely, between the motor unit and the compression unit.

Some of the liquid refrigerant discharged into the inner space S12a together with the gas refrigerant and oil may move to the outer space S12b through a communication path (not illustrated) disposed in the flow path guide or a communication groove (not illustrated) disposed between the lower surface of the flow path guide <NUM> and the upper surface of the compression unit. This liquid refrigerant may then stagnate in the lower space S1 of the casing <NUM> including the oil storage space S11 and the discharge space S12 through the series of processes that the liquid refrigerant moves to the oil storage space s11 together with returned oil.

On the other hand, the gas refrigerant, the oil, and some of the liquid refrigerant, discharged to the discharge space S12, may mainly flow toward the upper space S2 of the casing <NUM> through the inner passage 120a. Some of this fluid may be accelerated while flowing through the venturi tube <NUM> disposed in the upper space S2. This acceleration force may allow the liquid refrigerant in the discharge space S12, in which the second end 192b of the liquid refrigerant discharge tube <NUM> is located, to be suctioned toward the venturi tube <NUM>.

At this time, the gas refrigerant and the like may move toward the upper space S2 while maintaining the fastest speed through several inner passages 120a, which are located coaxially with or adjacent to the discharge through hole <NUM> among the inner passages 120a. Accordingly, when the venturi tube <NUM> overlaps the corresponding inner passages 120a in the axial direction as illustrated in this implementation, the liquid refrigerant within the discharge space S12 can be more quickly suctioned toward the upper space S2 by the gas refrigerant and the like that pass through the venturi tube <NUM> at the fast speed.

Then, the liquid refrigerant stagnated in the inner space 110a of the casing <NUM> through the liquid refrigerant discharge tube <NUM> connected to the small-diameter portion <NUM> of the venturi tube <NUM> may be suctioned into refrigerant passing through the venturi tube <NUM>, thereby being discharged to the outside of the compressor <NUM>. This can suppress an excessive amount of liquid refrigerant from remaining in the inner space 110a of the casing <NUM>, thereby preventing viscosity of oil within the casing <NUM> from being lowered.

This can also suppress the discharge of oil mixed with vaporized refrigerant during a normal operation. Accordingly, even if the compressor <NUM> is restarted after being exposed to a low-temperature state for a long time, a predetermined amount of oil or more can be secured in the casing <NUM> at the initial operation, thereby suppressing friction loss and wear due to a shortage of oil in the compressor <NUM>. In addition, when the air conditioner is re-operated, heating and cooling can be quickly resumed, thereby increasing satisfaction with use.

Hereinafter, a description will be given of another implementation of a liquid refrigerant discharge unit.

That is, the venturi tube is formed in the linear shape in the previous implementation but may also be formed in a bent shape in some cases.

<FIG> is a longitudinal sectional view illustrating another implementation of the venturi tube in <FIG>.

Referring to <FIG>, the venturi tube <NUM> according to this implementation may be configured such that the first large-diameter portion <NUM> and the second large-diameter portion <NUM> are parallel or intersect with each other. For example, the center line of the first large-diameter portion <NUM> and the center line of the second large-diameter portion <NUM> may not be coaxially disposed but may be disposed in parallel or to intersect with each other.

In this case, the first large-diameter portion <NUM> and the second large-diameter portion <NUM> may be bent in opposite directions and the small-diameter portion <NUM> may be linearly formed. Alternatively, although not illustrated in the drawings, the first large-diameter portion <NUM> and the second large-diameter portion <NUM> may be symmetrical with each other, and the small-diameter portion <NUM> may be bent a plurality of times. Otherwise, any structure in which the first large-diameter portion <NUM> and the second large-diameter portion <NUM> are parallel to each other may be applied.

The first large-diameter portion <NUM>, as illustrated in the previous implementation, may be disposed to axially face the slot 1211d, which is located at a portion at which the flow rate of refrigerant is the fastest, namely, coaxially with or adjacent to the discharge through hole <NUM>. The basic configuration of the first large-diameter portion <NUM> and the small-diameter portion <NUM> and the operating effects thereof are the same as those of the previous implementation of <FIG>, and thus a description thereof will be omitted.

However, the second large-diameter portion <NUM> may be disposed such that at least part of an upper end thereof overlaps the refrigerant discharge tube <NUM> in the axial direction. In other words, the second large-diameter portion <NUM> may be located eccentrically with respect to the first large-diameter portion <NUM>, but the upper end of the second large-diameter portion <NUM> may be disposed to face the inner end of the refrigerant discharge tube <NUM> in the axial direction.

As described above, the lower end of the first large-diameter portion <NUM> defining the inlet of the venturi tube <NUM> may be disposed at a position where the flow rate of refrigerant moving to the upper space S2 is the fastest. For example, the upper end of the second large-diameter portion <NUM> defining the outlet of the venturi tube <NUM> may be disposed to face the refrigerant discharge tube <NUM>.

In this case, most of the liquid refrigerant suctioned into the venturi tube <NUM> through the liquid refrigerant discharge tube <NUM> may be guided directly to the refrigerant discharge tube <NUM> without passing through the upper space S2. Accordingly, the liquid refrigerant stagnated in the inner space 110a of the casing <NUM> can be discharged more quickly and effectively, compared to the previous implementation.

Hereinafter, a description will be given of still another implementation of the liquid refrigerant discharge unit.

That is, in the previous implementation, the refrigerant discharge tube is disposed coaxially with the rotating shaft. However, in some cases, the refrigerant discharge tube may be disposed eccentrically with respect to the axial center of the rotating shaft.

<FIG> is a longitudinal sectional view illustrating another implementation of the refrigerant discharge tube in <FIG>.

As illustrated in <FIG>, the venturi tube <NUM> according to this implementation may be formed in a linear shape. For example, the first large-diameter portion <NUM> and the second large-diameter portion <NUM> may be coaxially disposed with each other. Since this is the same as the implementation of <FIG>, a detailed description thereof will be omitted.

However, in this implementation, the refrigerant discharge tube <NUM> may be disposed at an eccentric position with respect to the axial center O of the rotating shaft <NUM>. For example, the refrigerant discharge tube <NUM> may be located coaxially with the venturi tube <NUM>.

Specifically, the inner end 116a of the refrigerant discharge tube <NUM> may be disposed to overlap the inner passage 120a (or discharge through hole) in the axial direction above the stator coil <NUM>.

As described above, when the inner end 116a of the refrigerant discharge tube <NUM> overlaps the inner passage 120a (or discharge through hole) together with the venturi tube <NUM> in the axial direction, the liquid refrigerant passing through the venturi tube <NUM> may be guided directly toward the refrigerant discharge tube <NUM> without passing through the upper space S2. Accordingly, the liquid refrigerant stagnated in the inner space 110a of the casing <NUM> through the liquid refrigerant discharge tube <NUM> at the time of initial operation can be quickly discharged to the outside of the casing <NUM>.

Although not illustrated in the drawings, the refrigerant discharge tube <NUM> may alternatively be coupled through the casing <NUM> in a direction intersecting with the axial center O of the rotating shaft <NUM>. Even in this case, the refrigerant discharge tube <NUM> can be disposed adjacent to the outlet of the venturi tube <NUM>, thereby increasing a discharge speed of the liquid refrigerant.

That is, in the previous implementations, the separate venturi tube is disposed in the upper space of the casing. However, in some cases, the refrigerant discharge tube may be configured to serve as a kind of venturi tube.

<FIG> is a longitudinal sectional view illustrating another implementation of the liquid refrigerant discharge unit in <FIG> and <FIG> is a longitudinal sectional view illustrating another implementation of the refrigerant discharge tube in <FIG>.

Referring to <FIG>, the inner end of the refrigerant discharge tube <NUM> according to this implementation may communicate with the upper space S2 through the upper shell <NUM>. For example, the inner end 116a of the refrigerant discharge tube <NUM> may be inserted through the upper shell <NUM>. Here, the liquid refrigerant discharge tube <NUM> may be connected to a circumferential surface of the refrigerant discharge tube <NUM> in the upper space S2 of the casing <NUM>.

In other words, the venturi tube <NUM> applied to the previous implementations may be excluded from the upper space S2 of the casing <NUM>. Instead, the first end 192a of the liquid refrigerant discharge tube <NUM> may be connected to a periphery of the inner end 116a of the refrigerant discharge tube <NUM> in the inner space 110a of the casing <NUM>.

Even in this case, the basic configuration of the refrigerant discharge tube <NUM> and the liquid refrigerant discharge tube <NUM> and the operating effects thereof are similar to those of the previous implementations, and thus a detailed description thereof will be omitted. For example, the refrigerant discharge tube <NUM> may have the same inner diameter along its longitudinal direction. Accordingly, the refrigerant discharge tube <NUM> can provide the venturi effect and also the small-diameter portion <NUM> can be excluded from the refrigerant discharge tube <NUM>, such that the refrigerant can smoothly be discharged.

However, in this implementation, as described above, the venturi tube <NUM> may not be separately installed in the upper space S2 of the casing <NUM>, which can simplify the structure of the liquid refrigerant discharge unit <NUM> and facilitate manufacturing and installation of the liquid refrigerant discharge unit <NUM>.

In addition, in this implementation, the venturi tube <NUM> can be excluded, thereby securing a degree of design freedom for the upper space S2 of the casing <NUM>. For example, an expanded tube portion may be formed on or coupled to the inner end 116a of the refrigerant discharge tube <NUM>. Accordingly, the refrigerant within the upper space S2 can be more quickly guided into the refrigerant discharge tube <NUM> so as to be rapidly discharged toward the condenser <NUM>. This can improve the venturi effect in the refrigerant discharge tube <NUM>, resulting in effectively discharging the liquid refrigerant stagnated in the inner space 110a of the casing <NUM> even without the separate venturi tube <NUM>.

Referring to <FIG>, the refrigerant discharge tube <NUM> according to this implementation may be inserted through the upper shell <NUM> eccentrically from the axial center O of the rotating shaft <NUM> so as to communicate with the upper space S2. In this case, the inner end 116a of the refrigerant discharge tube <NUM>, as illustrated in the implementation of <FIG>, may be disposed to overlap the inner passage 120a (or discharge through hole) in the axial direction above the stator coil <NUM>.

As described above, when the inner end 116a of the refrigerant discharge tube <NUM> overlaps the inner passage 120a (or discharge through hole) in the axial direction, the refrigerant discharge tube <NUM> may serve as a kind of venturi tube. Accordingly, the liquid refrigerant stagnated in the inner space 110a of the casing <NUM> at the time of initial operation through the liquid refrigerant discharge tube <NUM> can be quickly discharged to the outside of the casing <NUM>. This can effectively prevent the occurrence of friction loss and wear due to lowered oil viscosity or a shortage of oil at the initial operation.

Although not illustrated in the drawings, the refrigerant discharge tube <NUM> may alternatively be configured as a venturi tube. In this case, the refrigerant discharge tube <NUM> may be formed such that the inner diameter of the small-diameter portion <NUM> is as large as possible or may be diverged into plural parts, so as to prevent or minimize flow resistance of the refrigerant passing through the refrigerant discharge tube <NUM>.

That is, in the previous implementations, the liquid refrigerant discharge tube is connected to the venturi tube or the refrigerant discharge tube inside the casing. However, in some cases, the liquid refrigerant discharge tube may alternatively be connected to the refrigerant discharge tube at the outside of the casing.

<FIG> is a longitudinal sectional view illustrating another implementation of the liquid refrigerant discharge unit in <FIG>.

Referring to <FIG>, the first end 192a of the liquid refrigerant discharge tube <NUM> according to this implementation may be connected to a middle portion of the refrigerant discharge tube <NUM> from the outside of the casing <NUM>, and the second end 192b of the liquid refrigerant discharge tube <NUM> may communicate with the inner space 110a of the casing <NUM> through the casing <NUM>.

The first end 192a of the liquid refrigerant discharge tube <NUM> may be connected between the compressor <NUM> and the condenser <NUM> or between the condenser <NUM> and the expander <NUM>. The second end 192b of the liquid refrigerant discharge tube <NUM> may be connected to the oil return groove 1211b defining the outer passage 120c, as illustrated in the previous implementations, through the casing <NUM>, or may communicate directly with the discharge space S12. <FIG> illustrates an example in which the second end 192b of the liquid refrigerant discharge tube <NUM> is directly connected to the discharge space S12.

When the second end 192b of the liquid refrigerant discharge tube <NUM> directly communicates with the discharge space S12, the entire outer passage 120c may be used as an oil return groove, unlike the previous implementations. This can secure a wider area of the oil return passage through which oil is returned from the upper space S2 to the oil storage space s11, thereby allowing smooth return of the oil.

Even when the refrigerant discharge tube <NUM> and the inner space 110a of the casing <NUM> communicate with each other through the liquid refrigerant discharge tube <NUM> disposed at the outside of the casing <NUM>, the basic configuration and the operating effect thereof are similar to those of the previous implementations, and thus a detailed description thereof will be omitted.

However, in this implementation, a control valve <NUM> may be disposed in the middle portion of the liquid refrigerant discharge tube <NUM>. The control valve <NUM> may be configured as a solenoid valve capable of selectively opening and closing the liquid refrigerant discharge tube <NUM>.

With this configuration, while the compressor <NUM> or an air conditioner including the compressor <NUM> is operating normally, refrigerant discharged through the refrigerant discharge tube <NUM> can be prevented from flowing back into the casing <NUM> through the liquid refrigerant discharge tube <NUM> or the refrigerant mixed with oil can be prevented from being discharged from the inner space 110a of the casing <NUM> through the liquid refrigerant discharge tube <NUM>.

The previous implementations illustrate the example employing the single liquid refrigerant discharge unit <NUM>, but the liquid refrigerant discharge unit <NUM> may be provided in plurality. Even in this case, the configuration of the liquid refrigerant discharging unit <NUM> and its basic effects may be the same as or similar to those of the previous implementations.

Claim 1:
A bottom-compression type high pressure scroll compressor, comprising:
a casing (<NUM>);
a motor unit (<NUM>; <NUM>) disposed in an inner space (110a) of the casing (<NUM>) to operate a rotating shaft (<NUM>; <NUM>);
wherein the inner space (110a) of the casing (<NUM>) is divided into a lower space (S1) and an upper space (S2) based on the motor unit (<NUM>, <NUM>);
a compression unit disposed at one side below the motor unit (<NUM>; <NUM>) in the lower space (S1) of the casing (<NUM>),
a discharge space (S12), which is a space defined between an upper surface of the compression unit a lower surface of the motor unit (<NUM>,<NUM>);
wherein the discharge space (S12) comprises an inner space (S12a) and an outer space (S12b) which communicate with each other;
wherein the compression unit has a discharge passage through which refrigerant compressed while the compression unit is driven by the rotating shaft (<NUM>; <NUM>) is discharged into the inner space (S12a) of the discharge space (S12);
a refrigerant discharge tube (<NUM>) having one end communicating with the upper space (S2) of the casing (<NUM>) and another end connectable to a refrigeration cycle, such that the refrigerant discharged from the inner space (S12a) of the discharge space (S12) into the upper space (S2) of the casing (<NUM>) through at least an inner passage (120a) flows to the refrigeration cycle;
being characterized in that it further comprises:
a venturi tube (<NUM>) disposed adjacent to the refrigerant discharge tube (<NUM>) in the upper space (S2);
wherein the venturi tube (<NUM>) includes a first large-diameter portion (<NUM>) and a second large-diameter portion (<NUM>) formed at both ends thereof to define a first open end and a second open end, respectively, and at least one small-diameter portion (<NUM>) formed between the first large-diameter portion (<NUM>) and the second large-diameter portion (<NUM>);
wherein one of the first and second open end of the venturi tube (<NUM>) overlaps at least partially the inner passage (120a); and
a liquid refrigerant discharge tube (<NUM>) having a first end connected to the at least one small-diameter portion (<NUM>) of the venturi tube (<NUM>) and a second end opposite to the first end of the liquid refrigerant discharge tube (<NUM>) and communicating with the outer space (S12b) of the discharge space (S12).