Patent Publication Number: US-2020284259-A1

Title: Oil separating apparatus and electronic compressor including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2019-0027046, filed on Mar. 8, 2019, the contents of which are incorporated by reference herein in their entirety. 
     BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
     The present disclosure relates to an oil separating apparatus and an electric compressor (or motor-operated compressor) including the same, and particularly, to an oil separating apparatus capable of effectively separating oil existing in a compressed refrigerant and an electric compressor including the same. 
     2. Background of the Disclosure 
     Compressors serving to compress a refrigerant in automotive air conditioning systems have been developed in various forms. Recently, electric compressors driven by electricity using motors have been actively developed. 
     For example, a scroll compression method suitable for a high compression ratio operation is mainly applied to an electric compressor. Such a scroll-type electric compressor (hereinafter referred to as an “electric compressor”) includes a motor unit, a compression unit, and a rotating shaft connecting the motor unit and the compression unit. 
     Specifically, the motor unit is provided as a rotating motor or the like and installed inside a hermetically sealed casing. The compression unit is located on one side of the motor unit and includes a fixed scroll and an orbiting scroll. The rotating shaft is configured to transmit a rotational force of the motor unit to the compression unit. 
     A refrigerant compressed in the compression unit is discharged to the outside of the electric compressor through an exhaust port. The discharged refrigerant is utilized for operating an automotive air conditioning system. 
     Currently, a lubricant or the like may be generally supplied to the electric compressor so that the refrigerant may be compressed smoothly. However, in the process of compressing the refrigerant, the lubricant and the refrigerant may be mixed. 
     It is not preferable to add a process for separating the lubricant and the refrigerant in the process of compressing the refrigerant in terms of compression efficiency of the refrigerant. Therefore, a technique for separating the refrigerant and the lubricant by providing an apparatus for separating the lubricant and the refrigerant to a discharge port through which the refrigerant is discharged from the outside of the compressor is known. 
     Patent Document 1 discloses an oil separating apparatus of a scroll compressor having an oil separating plate. More specifically, Patent Document 1 discloses an oil separating apparatus provided with an oil separating plate provided with a plurality of oil holes so that a refrigerant gas that has passed through a driving motor collides with the oil separating plate to allow gas and oil to be separated. 
     However, this type of oil separating apparatus has a limitation in that it can effectively separate the refrigerant gas and the oil when the oil separating apparatus is positioned on a lower side. That is, the oil separating apparatus is affected by a direction in which the scroll compressor is installed. 
     In addition, Patent Document 1 discloses a structure in which refrigerant gas is moved toward a gas discharge tube after the refrigerant gas hits the oil separating plate. That is, a solution is not provided when the oil is not separated from the refrigerant gas even after the refrigerant gas hits the oil separating plate. 
     Patent Document 2 discloses an oil separating apparatus for a scroll compressor capable of separating oil and a refrigerant gas by modifying a height of a lower end of a baffle portion or a shape of the baffle portion. Specifically, the height of the lower end of the baffle portion is formed to be a middle height of an intake pipe, or inclined on both upper and lower sides, disclosing an oil separating apparatus of a scroll compressor having the structure in which the refrigerant and oil do not hit the baffle portion or divided to flow into a driving motor. 
     However, this type of oil separating apparatus has limitations in that there is no consideration of a method for effectively separating the refrigerant and the oil. That is, the above related art focuses on a utilization method for a case where the refrigerant and the oil are not separated and does not provide a solution for separating the oil from the refrigerant for driving a refrigerating cycle. 
     Patent Document 3 discloses an electric compressor having an effect of improving oil separation efficiency. Specifically, Patent Document 3 discloses an electric compressor having a structure in which a thread is formed on the outer circumferential surface of an oil separation pipe to increase a movement distance of a refrigerant, thus enhancing oil separation efficiency. 
     However, this type of structure has limitations in that there is no consideration of measures for preventing pressure drop of the refrigerant according to the increase in the movement distance of the refrigerant. That is, maintaining the refrigerant at a high pressure is an essential condition for operating the refrigerating cycle but the pressure of the refrigerant drops to improve the separation efficiency. 
     In addition, the above-mentioned related art uses centrifugal separation, and there is a limitation in that the improvement of the oil separation efficiency is limited to a maximum efficiency of the centrifugal oil separation structure. Furthermore, the efficiency may be deteriorated depending on a size of an oil separating chamber. 
     PATENT DOCUMENTS 
     
         
         (Patent Document 1) Korean Patent Registration No. 10-0677521 (2007 Feb. 2.) 
         (Patent Document 2) Korean Patent Registration No. 10-1334250 (2013 Nov. 29.) 
       
    
     (Patent Document 3) Korean Patent Laid-open Publication No. 10-2015-0105000 (2015 Sep. 16.) 
     SUMMARY OF THE DISCLOSURE 
     Therefore, an aspect of the detailed description is to provide an oil separating apparatus having a structure capable of solving the above-mentioned problems and an electric compressor including the oil separating apparatus. 
     Another aspect of the detailed description is to provide an oil separating apparatus having a structure capable of separating a refrigerant and oil from a mixed fluid of the refrigerant and the oil during a refrigerant compression process, and an electric compressor including the same. 
     Another aspect of the detailed description is to provide an oil separating apparatus having a structure capable of effectively separating a refrigerant and oil without greatly changing a structure of an oil separating chamber, and an electric compressor including the same. 
     Another aspect of the detailed description is to provide an oil separating apparatus having a structure capable of increasing the possibility of collision and the number of collisions between a mixed fluid of a refrigerant and oil and an inner wall of the oil separating apparatus, and an electric compressor including the same. 
     Another aspect of the detailed description is to provide an oil separating apparatus having a structure capable of increasing the possibility of collision and the number of collisions between a mixed fluid of a refrigerant and oil and an inner wall of the oil separating apparatus, but not reducing a centrifugal force in an oil separating chamber, and an electric compressor including the same. 
     Another aspect of the detailed description is to provide an oil separating apparatus having a structure capable of effectively separating a refrigerant and oil while minimizing pressure loss of a compressed refrigerant, and an electric compressor including the same. 
     Another aspect of the detailed description is to provide an oil separating apparatus having a structure in which not only a refrigerant and oil are separated by a collision between a mixed fluid of a refrigerant and oil and an inner wall of the oil separating apparatus but a process of separating the refrigerant and the oil are further separated through a filtration apparatus, and an electric compressor including the same. 
     Another aspect of the detailed description is to provide an oil separating chamber having a structure in which a mixed fluid of a refrigerant and oil introduced into the oil separating apparatus can be effectively rotated, and an electric compressor including the same. 
     Another aspect of the detailed description is to provide an oil separating chamber having a structure in which a refrigerant and oil separated from each other can be effectively discharged, and an electric compressor including the same. 
     To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, an oil separating apparatus includes: a cylinder configured to receive flow of a mixed fluid of a refrigerant and an oil compressed in a compression unit, the cylinder comprising: a plurality of protrusions provided on an inner surface of the cylinder, the protrusions configured to separate the mixed fluid into the refrigerant and the oil, an exhaust port configured to discharge the separated refrigerant; and an oil discharge port configured to discharge the separated oil. 
     In addition, the plurality of protrusions of the oil separating apparatus may be spaced apart from each other by an interval in an inner circumferential direction of the cylinder. 
     The interval of the oil separating apparatus may be larger than a width of the protrusion. 
     In addition, the cylinder of the oil separating apparatus may be elongated in a longitudinal direction, and the plurality of protrusions may be spaced apart from each other by a distance in the longitudinal direction of the cylinder. 
     The distance of the oil separating apparatus may be larger than a length of the protrusion. 
     In the oil separating apparatus, a vortex finder may be disposed in an axial direction of the cylinder at an upper side and an inner space of the cylinder. 
     The vortex finder may include a mesh at a lower end portion of the vortex finder to separate a residual oil existing in the separated refrigerant. 
     Further, the cylinder of the oil separating apparatus may have a cylindrical shape elongated in the longitudinal direction of the cylinder. 
     In addition, the cylinder may be inclined downward so that a sectional area of the cylinder of the oil separating apparatus becomes narrower toward a lower side of the cylinder. 
     According to another aspect of the present invention, there is provided an electric compressor including: a motor including a stator and a rotated rotor spaced apart by a distance inside the stator; a compression unit including an orbiting scroll rotatably connected to the motor and a fixed scroll positioned adjacent to the orbiting scroll, the compression unit configured to compress a refrigerant by a relative rotation of the orbiting scroll; and an oil separating apparatus in communication with the compression unit to receive the compressed refrigerant from the compression unit, the compressed refrigerant including an oil, wherein the oil separating apparatus includes: a cylinder configured to receive flow of the compressed refrigerant from the compressed unit, the cylinder including a plurality of protrusions provided on an inner surface of the cylinder, the protrusions being configured to separate the oil from the compressed refrigerant. 
     The cylinder of the electric compressor may include: an oil discharge port positioned at a lower side of the cylinder and configured to discharge the separated oil; and an exhaust port positioned at an upper side of the cylinder and configured to discharge a refrigerant separated from the compressed refrigerant. In addition, the plurality of protrusions of the electric compressor may be spaced apart from each other by an interval in an inner circumferential direction of the cylinder. 
     The interval of the electric compressor may be larger than a width of the protrusion. 
     In addition, the cylinder of the electric compressor may be elongated in a longitudinal direction, and the plurality of protrusions may be spaced apart from each other by a distance in the longitudinal direction of the cylinder. 
     The distance of the electric compressor may be larger than a length of the protrusion. 
     A vortex finder disposed in an axial direction of the cylinder may be provided at an upper side and inner space of the cylinder 
     The electric compressor may include a mesh at a lower end portion of the vortex finder to separate a residual oil existing in the separated refrigerant. 
     In addition, the oil separating apparatus and the compression unit may communicate with each other via a mixed fluid inlet positioned on an outer circumference and an inner circumference of the cylinder and eccentric from a center of the cylinder at an interval. 
     According to the present invention, the following effects may be achieved. 
     First, the plurality of protrusions are provided in the cylinder of the oil separating apparatus. The mixed fluid of the refrigerant and the oil which has flowed into the inner space of the cylinder collides not only with the inner wall of the cylinder but also with the plurality of protrusions. 
     Therefore, the refrigerant and the oil may be effectively separated from the mixed fluid of the refrigerant and the oil. 
     Further, the plurality of protrusions are provided on the inner wall of the cylinder, and a large design change is not required for a structure outside the cylinder. 
     Therefore, the refrigerant and the oil may be effectively separated without greatly changing the structure of the oil separating chamber and the compressor. Further, the plurality of protrusions are provided to protrude from the inner wall of the cylinder to the inner side of the cylinder. Thus, a total surface area of the inner wall of the cylinder may be increased. 
     Therefore, the possibility of collision between the mixed fluid of the refrigerant and the oil and the inner wall of the cylinder and the number of collisions may be increased. Furthermore, the increased possibility of collision and the number of collisions allow the refrigerant and oil to be effectively separated from the mixed fluid. 
     Further, even though the plurality of protrusions are provided, the size of the inner diameter of the cylinder is not affected. That is, in the portion of the inner surface of the cylinder where the plurality of protrusions are not provided, the inner diameter of the cylinder is maintained. 
     Therefore, a centrifugal force in a direction from the cylinder center toward the outer circumference of the cylinder is not changed. Accordingly, the possibility of collision and the number of collisions are increased by the plurality of protrusions, but the centrifugal force inside the cylinder is not reduced. 
     Further, the refrigerant introduced into the cylinder further collides with the plurality of protrusions and a movement distance thereof within the cylinder is not increased. 
     Therefore, pressure drop of the refrigerant due to the increase of the movement distance may be prevented. As a result, it is possible to supply the refrigerant with sufficient pressure to operate the refrigerating cycle while effectively separating the refrigerant and the oil. 
     Further, the vortex finder provided in the inner space of the cylinder includes the mesh. Accordingly, the oil that may remain in the refrigerant from which oil was separated due to the collision with the inner wall of the cylinder or the plurality of protrusions may be separated again from the refrigerant by the mesh. 
     Therefore, the refrigerant and the oil may be separated not only by centrifugation and collision but also by the mesh. As a result, the refrigerant and the oil may be effectively separated. 
     Further, the mixed fluid of the refrigerant and the oil flows into the cylinder through the mixed fluid inlet formed so as to be eccentric from the center of the cylinder. 
     Thus, the refrigerant and the mixed fluid may be rotated, while effectively forming a vortex inside the cylinder. Accordingly, separation efficiency by the centrifugal force may be improved. 
     The exhaust port through which the separated refrigerant is discharged is located at an upper side of the cylinder, and the oil discharge port through which the separated oil is discharged is located at a lower side of the cylinder. 
     Therefore, the exhaust port and the oil discharge port are formed at positions corresponding to the respective densities of the separated refrigerant and oil, so that the refrigerant and the oil may be effectively discharged. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an electric compressor according to an embodiment of the present invention. 
         FIG. 2  is an exploded perspective view of each component of the electric compressor of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the electric compressor of  FIG. 1 . 
         FIG. 4  is a cross-sectional view showing an internal structure of an oil separating apparatus provided in the electric compressor of  FIG. 1 . 
         FIG. 5  is a plan view of the oil separating apparatus of  FIG. 4 . 
         FIG. 6  is a cross-sectional view showing an internal structure of an oil separating apparatus according to another embodiment of the present invention. 
         FIG. 7  is a cross-sectional view showing an internal structure of an oil separating apparatus according to another embodiment of the present invention. 
         FIG. 8  is a cross-sectional view showing an internal structure of an oil separating apparatus according to another embodiment of the present invention. 
         FIG. 9  is a view showing a flow of a refrigerant flowing in the electric compressor of  FIG. 1 . 
         FIG. 10  is a view showing a process in which a refrigerant and oil are separated and discharged by the oil separating apparatus of  FIG. 4 . 
         FIG. 11  is a view showing a process in which a refrigerant and oil are separated and discharged according to the oil separating apparatus of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Hereinafter, an oil separating apparatus and an electric compressor including the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
     In the following description, for the sake of clarity, a description of some components may be omitted. 
     The terms “front side,” “rear side,” “upper side,” “lower side,” “right side,” and “left side” as used in the following description may be understood with reference to a coordinate system illustrated in  FIGS. 1, 3, 4, and 6 to 11 . 
     When it is described that a certain element is “connected to” or “electrically connected to” a second element, the first element may be directly connected or electrically connected to the second element, but it should be understood that a third element may intervene therebetween. 
     On the other hand, when it is described that a certain element is “directly connected to” or “directly electrically connected to” a second element, it should be understood that there may be no third element therebetween. 
     In the description, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     The term “refrigerant” used in the following description refers to a certain medium that takes heat from a low temperature object and conveys it to a high temperature object. In one embodiment, the refrigerant may be carbon dioxide (CO 2 ), R134a, and the like. 
     The term “oil” as used in the following description refers to any fluid which may be mixed with or separated from a refrigerant, for the purpose of preventing or dispersing heat or abrasion that may occur in a frictional portion of a machine. In one embodiment, the oil may be a lubricant. 
     Referring to  FIGS. 1 to 3 , an electric compressor  1  according to the illustrated embodiment includes a compressor module  10 , an inverter module  20 , and a connector module  30 . 
     The compressor module  10  is a portion where a refrigerant is compressed. As will be described later, the compressor module  10  includes a compression unit  400  for compressing a refrigerant, a motor unit  200  for providing a rotational force to the compression unit  400 , and a rotating shaft unit  300  for transmitting a rotational force generated in the motor unit  200  to the rotating shaft unit  300 . In addition, the compressor module  10  includes a flow path portion  500  for flowing a refrigerant and oil therein, and an oil separating apparatus  600  for separating oil from the compressed refrigerant. A detailed description thereof will be given later. 
     The inverter module  20  controls the motor unit  200 . Specifically, the inverter module  20  controls rotation of the motor unit  200  and a rotation speed thereof. 
     Accordingly, a flow rate and pressure of the refrigerant compressed in the compression unit  400  may be controlled. To this end, the inverter module  20  may include a switching element (not shown), a semiconductor device (not shown), a printed circuit board (not shown), and the like. 
     The connector module  30  applies power and control signal to the inverter module  20 . In the illustrated embodiment, the connector module  30  includes a communication connector  32  for transmitting and receiving control signals and a power connector  34  for inputting power. 
     In the illustrated embodiment, the connector module  30  is provided in the inverter housing  130  to be described later, but it may also be provided at any position where power and control signal may be received. 
     The present invention further includes the oil separating apparatus  600  for effectively separating oil from a mixed fluid of compressed refrigerant and oil. The oil separating apparatus  600  will be described separately. 
     The housing unit  100  forms an appearance of the electric compressor  1 . That is, the housing unit  100  is a part where the electric compressor  1  is exposed to the outside. Therefore, it is preferable that the housing unit  100  is formed of a material having high insulation and high durability. 
     In the illustrated embodiment, the housing unit  100  includes a main housing  110 , a rear housing  120 , an inverter housing  130 , and an inverter cover  140 . 
     The main housing  110  forms a part of the appearance of the compressor module  10 . The main housing  110  accommodates the motor unit  200  that is rotated in response to a control signal from the inverter module  20 , the rotating shaft unit  300  that transmits a rotational force of the motor unit  200 , and the compression unit  400  driven by the rotational force transmitted by the rotating shaft unit  300 . 
     The main housing  110  has a refrigerant flow path portion  510  through which the refrigerant flows in and is compressed and discharged and an oil flow path portion  520  in which oil flows for smooth operation of the motor unit  200 , the rotating shaft unit  300 , and the compression unit  400 . 
     Inside the main housing  110 , a motor chamber S 1  in which the motor unit  200  is accommodated and a back pressure chamber S 3  in which the refrigerant is compressed are formed. 
     The main housing  110  is provided in a cylindrical shape elongated in a longitudinal direction, that is, in a front-rear direction in the illustrated embodiment. 
     The shape of the main housing  110  may be changed. However, considering that the main housing  110  is provided with the compression unit  400  that compresses the refrigerant at a high pressure, it is preferable that the main housing  110  is provided in a cylindrical shape having the highest rigidity with respect to an internal pressure. 
     The rear housing  120  is located on one side of the main housing  110 , and in the illustrated embodiment, the rear housing  120  is positioned on a front side. The main housing  110  is fluidly coupled with the rear housing  120 . 
     Specifically, a fixed scroll  420 , which will be described later, is provided between the main housing  110  and the rear housing  120 . The main housing  110  and the rear housing  120  are each fluidly connected to the fixed scroll  420 . 
     Accordingly, the compressed refrigerant may be discharged to the outside of the electric compressor  1  through the exhaust port  122  formed in the rear housing  120 . Further, the oil separated from the compressed refrigerant may be returned to the main housing  110  through the oil flow path portion  520 . 
     The inverter housing  130  is coupled to the other side of the main housing  110 , that is, to the rear side in the illustrated embodiment. In an embodiment not shown, the main housing  110  may be fluidly connected with the inverter housing  130 . 
     Accordingly, the refrigerant flowing into the main housing  110  flows into the inverter housing  130 , so that various devices (not shown) accommodated in the inverter housing  130  may be cooled. In this case, cooling efficiency of the inverter module  20  may be improved. 
     An intake port  112  is formed on one side of an outer circumferential surface of the main housing  110 , that is, on the rear side adjacent to the inverter housing  130  in the illustrated embodiment. 
     The intake port  112  communicates with the inside and the outside of the main housing  110 . The refrigerant may be introduced into the main housing  110  through the intake port  112 . The introduced refrigerant is compressed, while sequentially passing through the motor chamber  51 , the back pressure chamber S 3 , and the discharge chamber S 4 , and discharged to the outside of the electric compressor  1  through the exhaust port  122 . 
     An oldham ring  114  is provided between the main housing  110  and an orbiting scroll  410  to be described later. The oldham ring  114  serves to prevent rotation of the orbiting scroll  410 . The oldham ring  114  transmits the rotational force of the motor part  200  transmitted by the rotating shaft unit  300  to the orbiting scroll  410 . 
     Accordingly, the orbiting scroll  410  may be configured to be rotated by the oldham ring  114  only when the motor unit  200  is operated. 
     In an embodiment not shown, a rotation preventing mechanism including a pin and a ring other than the oldham ring  114  may be provided. The oldham ring  114  may be replaced with any form capable of preventing rotation of the orbiting scroll  410  and transmitting the rotational force of the rotating shaft unit  300  to the orbiting scroll  410 . 
     The rear housing  120  forms a part of the appearance of the electric compressor  1 . The rear housing  120  is provided with a discharge chamber S 4  through which the compressed refrigerant flows and the oil separating apparatus  600  for separating oil from the compressed refrigerant. 
     An oil flow path portion  520  for returning the oil separated from the compressed refrigerant to the main housing  110  is formed in the rear housing  120 . In addition, a separate flow path (not shown) may be provided in the rear housing  120  so that the compressed refrigerant may smoothly flow into the oil separating apparatus  600 . 
     The rear housing  120  is provided in the form of a cap having a circular cross-section. The shape of the rear housing  120  may be changed but is preferably determined to correspond to shapes of the main housing  110  and the fixed scroll  420 . 
     The rear housing  120  is located on one side of the main housing  110 , that is, on the front side in the illustrated embodiment. The rear housing  120  and the main housing  110  are fluidly connected. 
     Specifically, a fixed scroll  420 , which will be described later, is connected between the rear housing  120  and the main housing  110 . The rear housing  120  and the main housing  110  are fluidly connected with the fixed scroll  420 . 
     Accordingly, the compressed refrigerant may be discharged to the outside of the electric compressor  1  through the exhaust port  122  formed in the rear housing  120 . Further, the oil separated from the compressed refrigerant may be returned to the main housing  110  through the oil flow path portion  520 . 
     The discharge chamber S 4  is formed between the rear housing  120  and the fixed scroll  420 . The refrigerant compressed in the compression unit  400  is discharged to the discharge chamber S 4  and then flows into the oil separating apparatus  600  to be described later. 
     Accordingly, pressure drop of the refrigerant due to discharge resistance, which may occur when the compressed refrigerant flows directly into the oil separating apparatus  600 , may be prevented. 
     In a lower space of the rear housing  120 , an oil chamber S 5  is formed. In the oil chamber S 5 , the oil separated from the refrigerant in the oil separating apparatus  600  to be described later may be collected. The collected oil may be supplied to the compression unit  400  through the oil flow path portion  520  to be described later. 
     The exhaust port  122  is formed on one side of the outer circumferential surface of the rear housing  120 , that is, on the upper side of the front side facing the main housing  110  in the illustrated embodiment. 
     The exhaust port  122  allows the inside and the outside of the rear housing  120  to communicate with each other. The compressed refrigerant is discharged to the outside of the electric compressor  1  through the exhaust port  122 . 
     The position of the exhaust port  122  may be changed. However, considering a difference in density of the oil separated from the refrigerant discharged through the exhaust port  122 , the exhaust port  122  is preferably located at least above the oil discharge port  616 . 
     The exhaust port  122  communicates with the oil separating apparatus  600  to be described later. That is, the refrigerant compressed in the compression unit  400  flows into the oil separating apparatus  600  through the discharge chamber S 4 . The refrigerant flowing into the oil separating apparatus  600  is separated from the oil and then discharged to the outside of the electric compressor  1  through the exhaust port  122 . 
     The inverter housing  130  together with the inverter cover  140  forms an appearance of the inverter module  20 . Various electronic circuits or the like constituting the inverter module  20  are accommodated in a space formed by the inverter housing  130  and the inverter cover  140  being coupled to each other, that is, in the inverter chamber S 2 . 
     The inverter housing  130  is located on one side of the main housing  110 , that is, on the rear side of the main housing  110  in the illustrated embodiment. The inverter housing  130  is coupled to the main housing  110 . 
     In addition, in an embodiment not shown, the inverter housing  130  may be fluidly coupled with the main housing  110 . In this case, various electronic circuits constituting the inverter module  20  may be cooled by the refrigerant as described above. 
     A connector module  30  is provided on one side of the inverter housing  130 , that is, on the front side of the inverter housing  130  in the illustrated embodiment. The position of the connector module  30  may be changed as described above. 
     The inverter cover  140  is coupled to the inverter housing  130  to form an inverter chamber S 2  capable of accommodating various electronic circuits constituting the inverter module  20 . 
     The inverter cover  140  is located on one side of the inverter housing  130 , that is, on the rear side of the inverter housing  130  facing the main housing  110  in the illustrated embodiment. 
     The inverter cover  140  and the inverter housing  130  may be coupled by a separate fastening means (not shown). 
     A process of controlling the motor unit  200  to be described later by applying power and control signal to various electronic circuits accommodated in the inverter chamber S 2  and the like is a well-known technique, and a detailed description thereof will be omitted. 
     The motor unit  200  is accommodated in the motor chamber S 1  of the main housing  110  so that the compression unit  400  provides power for compressing the refrigerant. The motor unit  200  may be operated and controlled by power and control signal applied from the inverter module  20 . 
     The motor unit  200  is rotatably connected to the rotating shaft unit  300 . A rotational force generated by the motor unit  200  may be transmitted to the orbiting scroll  410  of the compression unit  400  through the rotating shaft unit  300 . 
     The motor unit  200  includes a stator  210  and a rotor  220 . When power is applied to the motor unit  200 , the stator  210  is not rotated but the rotor  220  is rotated relative to the stator  210 . The rotational force generated by rotation of the rotor  220  is transmitted to the orbiting scroll  410  through the rotating shaft unit  300 . 
     The stator  210  forms a magnetic field required for the motor unit  200  to be driven in accordance with power and control signal applied from the inverter module  20 . The magnetic field formed by the stator  210  provides a rotational force by which a magnet (not shown) provided in the rotor  220  may rotate. 
     In the illustrated embodiment, the stator  210  is positioned to surround the rotor  220  radially outside of the rotor  220 . That is, the stator  210  is provided in a cylindrical shape to partially accommodate the cylindrical rotor  220 . 
     An outer circumferential surface of the stator  210  may contact an inner circumferential surface of the motor chamber S 1 . In other words, the stator  210  may be fixed to the motor chamber S 1 . 
     In the illustrated embodiment, the stator  210  is provided in a cylindrical shape having a cylindrical hollow portion therein. The rotor  220  may be inserted into the hollow portion. 
     The stator  210  may be provided with a plurality of coils (not shown). When power and control signal are applied from the inverter module  20 , the plurality of coils (not shown) form a magnetic field. 
     A magnetic field formed by a plurality of coils (not shown) applies an electromagnetic force to a plurality of magnets (not shown) provided in the rotor  220 . At this time, it is preferable that the plurality of coils (not shown) are arranged so that a direction of the electromagnetic force applied to the plurality of magnets (not shown) is the same. 
     That is, the plurality of coils (not shown) may be arranged so that directions of magnetic fields formed by the respective coils (not shown) are alternately changed. 
     The rotor  220  is rotated by a magnetic field formed by the stator  210 . To this end, a plurality of coils (not shown) for forming a magnetic field are provided in the stator  210 , and a plurality of magnets (not shown) for receiving an electromagnetic force by the formed magnetic field are provided in the rotor  220 . 
     The rotating shaft unit  300  is rotatably coupled to the rotor  220  to be described later. Specifically, when the rotor  220  is rotated, the rotating shaft unit  300  is also configured to rotate together with the rotor  220 . With this configuration, the orbiting scroll  410 , which is rotatably coupled to the rotating shaft unit  300 , may receive the rotational force of the motor unit  200 . 
     The rotating shaft unit  300  transmits a rotational force generated by rotation of the motor unit  200  to the orbiting scroll  410 . 
     To this end, one side of the rotating shaft unit  300 , that is, the rear side in the illustrated embodiment, is coupled to the rotor  220 . Further, the other side of the rotating shaft unit  300 , that is, the front side in the illustrated embodiment, is coupled to the orbiting scroll  410 . 
     In the illustrated embodiment, the rotating shaft unit  300  is provided in a cylindrical shape extending in a longitudinal direction, but the shape thereof may be any shape capable of transmitting the rotational force of the motor unit  200  to the compression unit  400 . 
     The rotating shaft unit  300  includes a shaft portion  310 , a main bearing portion  320 , an eccentric portion  330 , a sub-bearing portion  340 , and an oil supply guide flow path  350 . 
     The shaft portion  310  is rotatably coupled to the rotor  220  of the motor unit  200 . The shaft portion  310  is located on one side of the rotating shaft unit  300  adjacent to the rotor  220 . 
     The main bearing portion  320  is rotatably supported in a radial direction by a shaft coupling portion (not shown) provided in the main housing  110 . In other words, the main bearing portion  320  is a portion where the rotating shaft unit  300  is coupled with the main housing  110 . 
     To this end, the main bearing portion  320  is formed to have a radius larger than the shaft portion  310 . The main bearing portion  320  is also located on one side of the shaft portion  310 , that is, on the front side facing the rotor  220  in the illustrated embodiment. 
     A balance weight  322  is provided on the rear side of the main bearing portion  320 . The balance weight  322  adjusts the center of gravity of the rotating shaft unit  300  so that the rotating shaft unit  300  may be stably rotated in accordance with rotation of the motor unit  200 . 
     The eccentric portion  330  is rotatably coupled to a rotating shaft coupling portion  416  of the orbiting scroll  410  of the compression unit  400 . The eccentric portion  330  is formed to have a central axis different from that of the rotating shaft unit  300 . In other words, when the rotating shaft unit  300  is rotated, the eccentric portion  330  is rotated about an axis different from the central axis of the rotating shaft unit  300 . 
     Accordingly, the orbiting scroll  410  coupled to the eccentric portion  330  may also be eccentrically rotated relative to rotation of the motor unit  200 . As a result, the refrigerant may be compressed in the space between the orbiting wrap  414  of the orbiting scroll  410  and the fixed wrap  424  of the fixed scroll  420 . 
     For this eccentric rotation, the eccentric portion  330  may be formed such that the center of gravity of the eccentric portion  330  is different from the center axis of the rotating shaft unit  300 . 
     The eccentric portion  330  is located on one side of the main bearing portion  320 , that is, the front side facing the shaft portion  310  in the illustrated embodiment. 
     A third oil flow path  526 , which will be described later, is formed through the outer circumferential surface of the eccentric portion  330 . The oil separated from the compressed refrigerant may be supplied again to the compression unit  400  through the third oil flow path  526 . A detailed description thereof will be given later. The sub-bearing portion  340  is rotatably coupled to a rotating shaft coupling portion (not shown) of the fixed scroll  420  of the motor unit  400  and is supported in a radial direction. The sub-bearing portion  340  may pass through the rotating shaft coupling portion  416  of the orbiting scroll  410 . 
     Specifically, the eccentric portion  330  penetrates so as to be coupled to the rotating shaft coupling portion  416  formed on the orbiting end plate portion  412  of the orbiting scroll  410 . The sub-bearing portion  340  passes through the rotating shaft coupling portion  416  of the orbiting scroll  410  and is rotatably coupled to the rotating shaft coupling portion (not shown) of the fixed scroll  420 . 
     In the illustrated embodiment, the sub-bearing portion  340  is formed to have a radius smaller than the eccentric portion  330 . Therefore, the sub-bearing portion  340  is not constrained in the radial direction by the rotating shaft coupling portion  416  of the orbiting scroll  410 . 
     The sub-bearing portion  340  is located on one side of the eccentric portion  330 , that is, the front side facing the main bearing portion  320  in the illustrated embodiment. 
     The oil supply guide flow path  350  is a passage through which the oil separated from the compressed refrigerant flows into the third oil flow path  526 . To this end, the oil supply guide flow path  350  communicates with the third oil flow path  526  and the first oil flow path  522 . 
     The oil supply guide flow path  350  may be formed in the longitudinal direction of the sub-bearing portion  340 , that is, in the front-rear direction in the illustrated embodiment. In one embodiment, the oil supply guide flow path  350  may be formed on the center axis of the sub-bearing portion  340 . 
     The compression unit  400  is rotated according to rotation of the motor unit  200  to substantially compress the refrigerant. The compression unit  400  is rotatably connected to the motor unit  200  by the rotating shaft unit  300 . 
     The compression unit  400  includes the orbiting scroll  410  and the fixed scroll  420 . 
     The orbiting scroll  410  is rotated by rotation of the motor unit  200 . Specifically, the orbiting scroll  410  is rotatably connected to the eccentric portion  330  of the rotating shaft unit  300 . 
     When the motor unit  200  is rotated, the eccentric unit  330  is rotated to have a center axis different from that of the rotating shaft unit  300  and the motor unit  200 . That is, the eccentric portion  330  is eccentrically rotated about the central axis of the motor unit  200 . 
     Accordingly, the orbiting scroll  410  rotatably coupled to the eccentric portion  330  is also eccentrically rotated with respect to the center axis of the motor unit  200 . As will be described later, the fixed scroll  420  is disposed so as to have the same central axis as that of the motor unit  200 . 
     Accordingly, the orbiting scroll  410  is rotated relative to the fixed scroll  420 , but eccentrically rotated. Accordingly, the refrigerant may be compressed in the space between the orbiting wrap  414  of the orbiting scroll  410  and the fixed wrap  424  of the fixed scroll  420 . 
     The orbiting scroll  410  may be accommodated in the main housing  110 . 
     The orbiting scroll  410  includes an orbiting disk plate portion  412 , an orbiting wrap  414 , and a rotating shaft coupling portion  416 . 
     The orbiting disk plate portion  412  forms one side of the orbiting scroll  410 . In the illustrated embodiment, the orbiting disk plate portion  412  forms the rear side of the orbiting scroll  410 . 
     One side of the orbiting disk plate portion  412 , that is, the front side surface in the illustrated embodiment, may be in contact with the rear side surface of the fixed scroll  420 . 
     The orbiting wrap  414  is coupled with the fixed wrap  424  of the fixed scroll  420  to form a predetermined space. The orbiting wrap  414  in a state of being coupled with the fixed wrap  424  may be eccentrically rotated with respect to the rotating shaft unit  300 . Thus, the refrigerant may be compressed in the space between the orbiting wrap  414  and the fixed wrap  424 . 
     The orbiting wrap  414  protrudes from the orbiting disk plate portion  412 . In the illustrated embodiment, the orbiting wrap  414  protrudes from the front side surface of the orbiting disk plate portion  412 . 
     In the illustrated embodiment, the orbiting wrap  414  is formed in a spiral shape but may be any shape which can be coupled and engaged with the fixed wrap  424  and eccentrically rotated relative to the fixed wrap  424 . 
     The rotating shaft coupling portion  416  is a portion to which the rotating shaft unit  300  is coupled. Specifically, the eccentric portion  330  of the rotating shaft unit  300  penetrates to be coupled to the rotating shaft coupling portion  416 . 
     The rotating shaft coupling portion  416  is formed to pass through the orbiting disk plate portion  412 . In the illustrated embodiment, the rotating shaft coupling portion  416  is formed to pass through the orbiting scroll  410  in a front-rear direction of the orbiting scroll  410 . 
     A radius of the rotating shaft coupling portion  416  is preferably determined to be equal to or slightly larger than an outer diameter of the eccentric portion  330  so that the eccentric portion  330  penetrates to be coupled to the rotating shaft coupling portion  416 . 
     The fixed scroll  420  is not rotated regardless of rotation of the motor unit  200 . Accordingly, when the motor unit  200  is rotated, the orbiting scroll  410  may be eccentrically rotated relative to the fixed scroll  420 . 
     The fixed scroll  420  is positioned on one side of the main housing  110 , that is, the front side facing the inverter module  20  in the illustrated embodiment. The outer surface of the fixed scroll  420  may be exposed to the outside. 
     One side of the fixed scroll  420 , that is, the rear side in the illustrated embodiment, may be in contact with the front side of the main housing  110 . Further, a separate fastening member (not shown) may be provided to couple the fixed scroll  420  and the main housing  110  together. 
     The fixed scroll  420  is rotatably coupled with the orbiting scroll  410 . As described above. The fixed scroll  420  is fixed and the orbiting scroll  410  is rotated relative to the fixed scroll  420 . 
     The fixed scroll  420  includes a fixed disk plate portion  422 , a fixed wrap  424 , a discharge valve  426 , and a refrigerant discharge port  428 . 
     In addition, a rotating shaft coupling portion (not shown) is formed in the fixed scroll  420 , so that the sub-bearing portion  340  of the rotation shaft portion  300  may be rotatably coupled thereto. 
     However, as described above, the fixed scroll  420  is not rotated regardless of rotation of the motor unit  200 . Accordingly, the rotating shaft coupling portion (not shown) of the fixed scroll  420  may be considered to support the rotating shaft unit  300 . 
     The fixed disk plate portion  422  forms one side of the fixed scroll  420 . In the illustrated embodiment, the fixed disk plate portion  422  forms the rear side of the fixed scroll  420 . 
     One side of the fixed disk plate portion  422 , that is, the front side surface in the illustrated embodiment, may be in contact with the front side surface of the orbiting scroll  410 . 
     In the illustrated embodiment, a plurality of recesses are formed on an outer circumferential surface of the fixed disk plate portion  422 . This is to reduce a weight of the electric compressor  1 , and a shape and number of the plurality of recesses may be changed. 
     The fixed wrap  424  is coupled with the orbiting wrap  414  of the orbiting scroll  410 , while forming a predetermined space. When the orbiting scroll  410  is rotated according to rotation of the motor unit  200  after the fixed wrap  424  is coupled with the orbiting wrap  414 , the refrigerant may be compressed in the space between the fixed wrap  424  and the orbiting wrap  414   
     The fixed wrap  424  protrudes from the fixed disk plate portion  422 . In the illustrated embodiment, the fixed wrap  424  protrudes to the rear side from the fixed disk plate portion  422 . 
     In the illustrated embodiment, the fixed wrap  424  is formed in a spiral shape but may have any shape which may be coupled to be engaged with the orbiting wrap  414  so that the orbiting wrap  414  is relatively eccentric so as to be rotated with respect to the fixed wrap  424 . 
     The discharge valve  426  is configured to open or close the refrigerant discharge port  428 , which is a passage through which the refrigerant compressed by the relative rotation of the orbiting scroll  410  and the fixed scroll  420  flows into the discharge chamber S 4 . 
     In one embodiment, the discharge valve  426  may be provided as a check valve, such as a reed valve, which restricts a fluid flow in a single direction of opening and closing according to a pressure. 
     The discharge valve  426  is located on one side of the fixed disk plate portion  422  facing the fixed wrap  424 , that is, on the front side in the illustrated embodiment. Further, the discharge valve  426  is configured to cover the refrigerant discharge port  428 . 
     When a pressure of the compressed refrigerant is equal to or higher than a predetermined pressure, the discharge valve  426  opens the refrigerant discharge port  428 . Thus, the compressed refrigerant may flow into the discharge chamber S 4 . 
     When the pressure of the compressed refrigerant is less than the predetermined pressure, the discharge valve  426  closes the refrigerant discharge port  428 . As a result, the refrigerant with insufficient pressure is prevented from flowing into the discharge chamber S 4 . 
     The refrigerant discharge port  428  is a passage through which the refrigerant compressed by the orbiting scroll  410  and the fixed scroll  420  flows into the discharge chamber S 4 . The refrigerant discharge port  428  fluidly connects the discharge chamber S 4  with the space formed between the orbiting wrap  414  and the fixed wrap  424 . 
     The refrigerant discharge port  428  is configured to be opened or closed. Specifically, the refrigerant discharge port  428  is provided with a discharge valve  426 , and the refrigerant discharge port  428  may be opened or closed according to a pressure of the compressed refrigerant. 
     As the refrigerant discharged through the refrigerant discharge port  428  flows into the oil separating apparatus  600  through the discharge chamber S 4 , without directly flowing into the oil separating apparatus  600  to be described later, a discharge resistance applied to the refrigerant may be reduced. Accordingly, the pressure drop of the compressed refrigerant may be minimized. 
     The flow path portion  500  is a passage through which a refrigerant and oil flow. The flow path portion  500  is formed across the main housing  110  and the rear housing  120 . 
     In an embodiment not shown, the flow path portion  500  may also be formed in the inverter module  20 . In this case, the refrigerant may directly cool various electronic circuits constituting the inverter module  20  as described above. 
     The flow path portion  500  includes a refrigerant flow path portion  510  and an oil flow path portion  520 . 
     The refrigerant flow path portion  510  is a passage through which the refrigerant flows. The refrigerant flow path portion  510  is defined by a space formed in the main housing  110 . Alternatively, the refrigerant flow path portion  510  may be formed by a separate refrigerant flow path forming member (not shown). 
     The refrigerant flow path portion  510  includes a first refrigerant flow path  512  and a second refrigerant flow path  514 . 
     The first refrigerant flow path  512  communicates the motor chamber S 1  and the second refrigerant flow path  514 . The refrigerant flowing into the motor chamber S 1  of the main housing  110  through the intake port  112  is transferred to the second refrigerant flow path  514  through the first refrigerant flow path  512 . In the illustrated embodiment, the first refrigerant flow path  512  is located in a lower space inside the main housing  110 . The first refrigerant flow path  512  may be an arbitrary position that allows the motor chamber S 1  and the second refrigerant flow path  514  to communicate with each other. 
     The second refrigerant flow path  514  allows the first refrigerant flow path  512  and the compression unit  400  to communicate with each other. Specifically, the refrigerant that has passed through the first refrigerant flow path  512  flows into the second refrigerant flow path  514 . 
     The refrigerant flowing into the second refrigerant flow path  514  is moved to a space formed between the orbiting scroll  410  and the fixed scroll  420 , and is compressed to have a predetermined pressure. The compressed refrigerant flows into the discharge chamber S 4  through the refrigerant discharge port  428  of the fixed scroll  420 . 
     The refrigerant flow path portion  510  may include a refrigerant guide member (not shown) configured to restrict a movement direction of the refrigerant flowing in the refrigerant flow path unit  510 . 
     The oil flow path portion  520  is a passage through which oil flows. The oil flow path portion  520  is defined by a space formed in the main housing  110  and the rear housing  120 . Alternatively, the oil flow path portion  520  may be formed by a separate oil flow path forming member (not shown). 
     The oil flow path portion  520  includes a first oil flow path  522 , a second oil flow path  524 , and a third oil flow path  526 . 
     The first oil flow path  522  allows the oil chamber S 5  formed in the inner space of the rear housing  120  and the oil supply guide flow path  350  to communicate with each other. The oil separated from the refrigerant in the oil separating apparatus  600  to be described later is collected in the oil chamber S 5 . 
     The oil collected in the oil chamber S 5  is transferred to the oil supply guide flow path  350  of the rotating shaft unit  300  through the first oil flow path  522 . In order to smoothly move the oil, the first oil flow path  522  may be provided with a power device (not shown) for providing a transfer force to the oil. 
     The second oil flow path  524  allows a space between the eccentric portion  330  and the rotating shaft coupling portion  416  and the oil supply guide flow path  350  to communicate with each other 
     The oil introduced through the second oil flow path  524  is supplied between the eccentric portion  330  and the rotating shaft coupling portion  416  of the orbiting scroll  410 . In other words, the oil flows into the space between the outer circumferential surface of the eccentric portion  330  and the rotating shaft coupling portion  416 . 
     As a result, friction due to rotation of the orbiting scroll  410  is relieved, and the refrigerant may be efficiently compressed. 
     The third oil flow path  526  allows a space between the sub-bearing portion  340  and the rotating shaft coupling portion (not shown) of the fixed scroll  420  and the oil supply guide flow path  350  to communicate with each other. 
     The oil flowing in through the third oil flow path  526  is supplied between the sub-bearing portion  340  and the rotating shaft coupling portion (not shown) of the fixed scroll  420 . In other words, the third oil flow path  526  flows into the space between the outer circumferential surface of the sub-bearing portion  340  and the rotating shaft coupling portion (not shown) of the fixed scroll  420 . 
     As a result, friction due to rotation of the rotating shaft unit  300  is relieved, and the refrigerant may be efficiently compressed. 
     The oil flowing into the compression unit  400  may be mixed with the refrigerant flowing into the compression unit  400  through the refrigerant flow path unit  510 . The mixed fluid of the compressed refrigerant and the oil flows into the discharge chamber S 4 , and a process of separating the refrigerant and the oil is performed first. 
     The refrigerant flowing into the main housing  110  is compressed through the above-described structure. At this time, not only the refrigerant but also oil for smooth rotation is supplied to the compression unit  400 . 
     Thus, the oil may be mixed during the compression of the refrigerant. When the mixed fluid of compressed refrigerant and oil (hereinafter referred to as “mixed fluid” is discharged to the outside of the electric compressor  1  and flows into the refrigerating cycle, efficiency of the cycle may deteriorate, and the device may be broken down. 
     Therefore, the mixed fluid discharged from the compression unit  400  undergoes a primary oil separation process in the discharge chamber S 4 . 
     The electric compressor  1  according to an embodiment of the present invention includes the oil separating apparatus  600  for separating the oil from the mixed fluid flowing thereto through the discharge chamber S 4 . The oil separating apparatus  600  may include a plurality of protrusions  640  to effectively separate oil from the mixed fluid. 
     Hereinafter, the oil separating apparatus  600  according to an embodiment of the present invention will be described in detail with reference to  FIGS. 4 to 8 . 
     The oil separating apparatus  600  is located in an upper space inside the rear housing  120  (see  FIG. 3 ). The oil separating apparatus  600  communicates with the discharge chamber S 4  and the oil chamber S 5 . 
     The oil separating apparatus  600  includes a cylinder  610 , a vortex finder  620 , a mesh  630 , and a protrusion  640 . 
     The cylinder  610  forms an appearance of the oil separating apparatus  600 . In the illustrated embodiment, the cylinder  610  is a cylindrical shape elongated in a vertical direction, but its shape may be changed. 
     A plurality of protrusions  640  are formed on an inner wall  612  of the cylinder  610 . The mixed fluid flowing into the inner space of the cylinder  610  collides with the plurality of protrusions  640 , so that the oil of the mixed fluid may be effectively separated. A detailed description thereof will be given later. 
     A mixed fluid inlet  614  is formed on one side of the cylinder  610 , that is, on the rear side in the illustrated embodiment. The mixed fluid inlet  614  allows the internal space of the cylinder  610  and the discharge chamber S 4  to communicate with each other. The mixed fluid flowing into the discharge chamber S 4  may flow into the inner space of the cylinder  610  through the mixed fluid inlet  614 . 
     The mixed fluid inlet  614  may be formed to be eccentric at a predetermined interval with respect to the central axis of the cylinder  610  (see  FIG. 5 ). In other words, the mixed fluid inlet  614  may be formed so that a straight line extending from the mixed fluid inlet  614  is directed to a space separated from a central axis of the cylinder  610 . 
     In this case, the mixed fluid introduced through the mixed fluid inlet  614  may form a vortex more smoothly in the inner space of the cylinder  610 . Therefore, a centrifugation effect of the mixed fluid may be improved. 
     In the illustrated embodiment, the mixed fluid inlet  614  is formed on the upper side of the cylinder  610  but its position may be changed. However, it is preferable that the mixed fluid inlet  614  is located on the upper side, considering that it is preferable that more rotation and collision occur in the process of separating the oil from the mixed fluid. 
     An oil discharge port  616  is formed on one side of the cylinder  610 , that is, on the front side in the illustrated embodiment. A direction of the oil discharge port  616  may be changed. 
     The oil discharge port  616  allows the inner space of the cylinder  610  and the oil chamber S 5  to communicate with each other. The oil separated from the mixed fluid may be discharged through the oil discharge port  616  and collected in the oil chamber S 5 . 
     In the illustrated embodiment, the oil discharge port  616  is formed on the lower side of the cylinder  610 , but its position may be changed. However, it is preferable that the oil discharge port  616  is located below the cylinder  610 , considering that the separated oil is moved downward due to a density difference. 
     The vortex finder  620  allows the mixed fluid flowing into the inner space of the cylinder  610  to effectively form a vortex. 
     The vortex finder  620  is positioned above the cylinder  610 . In the illustrated embodiment, the vortex finder  620  is cylindrical in shape extending downward from the inner space of the cylinder  610 , but its shape may be changed. 
     An extending length of the vortex finder  620  is preferably determined in consideration of oil separation efficiency of the mixed fluid and pressure drop of the compressed refrigerant. 
     Specifically, as the extending length of the vortex finder  620  is increased, a distance in an up-and-down direction of the vortex that may be formed by the mixed fluid increases, so that oil separation efficiency of the mixed fluid may be improved. 
     On the other hand, as the distance in which the mixed fluid flows increases, the pressure drop of the compressed refrigerant also increases. In this case, in order to improve the oil separation efficiency, the refrigerant may be lowered to an appropriate level or less and efficiency of the refrigerating cycle may be lowered. 
     Therefore, it is preferable that the downward extending length of the vortex finder  620  is determined in consideration of the above two factors. 
     The central axis of the vortex finder  620  may be aligned with the central axis of the cylinder  610 . In other words, the vortex finder  620  may be disposed coaxially with the cylinder  610 . 
     In the vortex finder  620 , an exhaust port  122  is formed in a longitudinal direction, that is, in a vertical direction in the illustrated embodiment. The refrigerant in which the oil was separated from the mixed fluid may be discharged to the outside of the electric compressor  1  through the exhaust port  122 . 
     In the embodiment illustrated in  FIG. 6 , a mesh  630  may be provided at one end of the vortex finder  620 , that is, at a lower end of the vortex finder  620  in the illustrated embodiment. The mesh  630  additionally filters the oil that may remain in the refrigerant from which oil was separated by centrifugation and collision with the plurality of protrusions  640  to be described later. 
     Therefore, in the embodiment having the mesh  630 , the oil of the mixed fluid may be additionally separated not only by the centrifugation and the collision but also by the particle size, so that oil separation efficiency may be further improved. 
     In the embodiment shown in  FIGS. 7 and 8 , the cylinder  610  may be formed to be inclined downward. More specifically, the cylinder  610  may be formed to have a reduced cross-sectional area toward a lower side. 
     Accordingly, in the illustrated embodiment, the cylinder  610  may be provided in the form of a cyclone, so centrifugation efficiency may be improved. In addition, the number of collisions with the inner wall of the cylinder  610  and the plurality of protrusions  640  is increased toward a lower side, so that separation efficiency due to the collision may also be improved. 
     In addition, in the illustrated embodiment, the mesh  630  may be provided at the lower end of the vortex finder  620 . As a result, oil separation efficiency may be further improved. 
     A plurality of protrusions  640  are provided and protrude from the inner wall of the cylinder  610 . The plurality of protrusions  640  may be formed to have the same or different width W and length L. 
     In the illustrated embodiment, the plurality of protrusions  640  are in the shape of a rectangular parallelepiped, but the shape thereof may be changed. 
     In the illustrated embodiment, the plurality of protrusions  640  may be a total of 12 protrusions  640  and spaced apart from each other at a predetermined distance D 1  in the inner circumferential direction of the cylinder  610 , but the number of the protrusions  640  may be changed. 
     It is preferable that the predetermined distance D 1  between the plurality of protrusions  640  is at least equal to or larger than the width W of each of the protrusions  640 . 
     The inner circumferential arrangement of each surface of each protrusion  640  facing the center axis of the cylinder  610  may become compact when the predetermined interval D 1  is formed smaller than the width W of the protrusion  640 . 
     In this case, the inner diameter of the cylinder  610  is reduced by each side of the protrusion  640 , so that the centrifugation efficiency may be reduced. 
     Also, as the inner diameter of the cylinder  610  is reduced, a surface area in which the mixed fluid may collide may also be reduced, so that the separation efficiency due to the collision may be reduced. 
     Therefore, it is preferable that the predetermined interval D 1  is formed to be equal to or larger than the width W of the protrusion  640 . 
     In addition, the plurality of protrusions  640  are spaced apart from each other by a predetermined distance D 2  in a height direction of the cylinder  610 , and a total of four protrusions  640  are provided for each column, but the number thereof may be changed. 
     It is preferable that the predetermined distance D 2  at which the plurality of protrusions  640  are separated is at least equal to or larger than the height L of each protrusion  640 . 
     If the predetermined distance D 2  is formed to be smaller than the length L of the protrusion  640 , the axial arrangement of the respective surfaces of the protrusions  640  toward the center axis of the cylinder  610  may become dense. 
     In this case, the inner diameter of the cylinder  610  may be reduced by each side of the protrusion  640 , so that the centrifugation efficiency may be reduced. 
     Also, as the inner diameter of the cylinder  610  is reduced, the surface area with which the mixed fluid may collide may also be reduced, so that the separation efficiency due to the collision may be reduced. 
     Therefore, it is preferable that the predetermined distance D 2  is formed to be equal to or larger than the length L of the protrusion  640 . 
     The plurality of protrusions  640  may be arranged alternately in each column. More specifically, a row in which the protrusions  640  are arranged and a row in which the protrusions  640  are not arranged along the inner circumference of the cylinder  610  may be alternately arranged on a cross-section of the cylinder  610  at a certain height, 
     An arrangement method of the plurality of protrusions  640  may be any method capable of improving the separation efficiency based on the collision. 
     Hereinafter, a process of separating oil from the mixed fluid in the oil separating apparatus  600  and the electric compressor  1  including the oil separating apparatus  600  according to an embodiment of the present invention will be described in detail with reference to  FIGS. 9 to 11 . 
     The refrigerant introduced through the intake port  112  flows into the refrigerant flow path portion  510  through the motor chamber S 1 . The refrigerant having passed through the first refrigerant flow path  512  and the second refrigerant flow path  514  is moved to the compression unit  400 . 
     The refrigerant is compressed by relative rotation of the orbiting scroll  410  and the fixed scroll  420 . 
     At this time, oil is supplied through the oil flow path portion  520  for smooth rotation of the motor unit  200 , the rotating shaft unit  300  and the compression unit  400 . A portion of the supplied oil is mixed with the compressed refrigerant. 
     The mixed fluid in which the compressed refrigerant and the oil are mixed is discharged to the discharge chamber S 4  through the refrigerant discharge port  428 . The oil of the mixed fluid is primarily separated in the discharge chamber S 4 . 
     The mixed fluid that has passed through the discharge chamber S 4  flows into the inner space of the cylinder  610  through the mixed fluid inlet  614  of the oil separating apparatus  600 . 
     At this time, the mixed fluid inlet  614  is formed to be eccentric from the central axis of the cylinder  610  at a predetermined interval. Further, the vortex finder  620  disposed coaxially with the cylinder  610  is provided on the upper side of the cylinder  610 . 
     Thus, the mixed fluid introduced through the mixed fluid inlet  614  forms a vortex in the inner circumferential direction of the cylinder  610 . Accordingly, the oil having a high density is centrifugated and moved to the lower side of the cylinder  610  (see  0  in  FIGS. 10 and 11 ). 
     On the other hand, the mixed fluid which is rotated in the internal space of the cylinder  610 , while forming a vortex, collides with the inner wall  612  of the cylinder  610 . The mixed fluid also collides with the plurality of protrusions  640  protruding from the inner wall  612  of the cylinder  610 . 
     Therefore, the oil is separated from the mixed fluid by the collision and is moved to the lower side of the cylinder  610  (see  0  in  FIGS. 10 and 11 ). 
     The oil is separated from the mixed fluid and the compressed refrigerant remains. The compressed refrigerant is discharged to the outside of the electric compressor  1  through the exhaust port  122  penetrating through the vortex finder  620 . 
     In the embodiment shown in  FIG. 11 , the mesh  630  is provided at the lower end of the vortex finder  620 . 
     Accordingly, in the process in which the compressed refrigerant enters the exhaust port  122 , the oil that may remain in the refrigerant is further filtered by the mesh  630 . 
     The oil separating apparatus  600  according to an embodiment of the present invention includes a plurality of protrusions  640  provided on the inner wall  612  of the cylinder  610 . 
     The plurality of protrusions  640  increases a surface area of the cylinder  610  with which the mixed fluid may collide, so that the possibility of collision of the mixed fluid is increased. Also, the possibility that the mixed fluid, which rotates as a vortex inside the cylinder  610 , collides with the side surface of the plurality of protrusions  640  is also increased. 
     Thus, the oil of the mixed fluid is not only centrifugated but also may be separated by collision with the inner wall  612  of the cylinder  610  and the plurality of protrusions  640 . As a result, separation efficiency of the oil from the mixed fluid may be improved. 
     The plurality of protrusions  640  protrude from the inner wall  612  of the cylinder  610 . Therefore, the size of the cylinder  610  may not be excessively increased, without requiring a change in an external structure of the cylinder  610 . 
     Therefore, the refrigerant and the oil may be effectively separated without greatly changing the structure of the oil separating apparatus  600  and the electric compressor  1 . 
     The predetermined distance D 1  by which the plurality of protrusions  640  are spaced apart from each other in the inner circumferential direction is determined to be equal to or larger than the width W of the protrusions  640 . Therefore, even though the plurality of protrusions  640  are provided, the inner diameter of the cylinder  610  does not change greatly. 
     Accordingly, centrifugation efficiency due to the mixed fluid flowing as a vortex inside the cylinder  610  is not reduced. As a result, the oil may be effectively separated from the mixed fluid. 
     Further, even though the plurality of protrusions  640  are formed, a movement distance of the mixed fluid introduced into the cylinder  610  is not increased. At the same time, the number of collisions and the possibility of collision between the mixed fluid and the plurality of protrusions  640  are increased. 
     Accordingly, since the movement distance of the mixed fluid in the oil separating apparatus  600  is not increased, pressure drop of the compressed refrigerant may be minimized. 
     Also, the mesh  630  is provided at one end of the vortex finder  620  to filter the oil that may remain in the compressed refrigerant entering the exhaust port  122 . 
     Accordingly, since the oil in the mixed fluid is discharged through the exhaust port  122  after centrifugation, separation by collision, and filtering by the mesh  630 , oil separation efficiency may be improved. 
     The mixed fluid inlet  614  through which the mixed fluid flows into the cylinder  610  from the discharge chamber S 4  is formed to be eccentric by a predetermined distance from the center of the cylinder  610 . 
     Therefore, when the mixed fluid flows into the cylinder  610 , it may naturally form a vortex and flow into the cylinder  610  without a separate member, so that efficiency of centrifugation may be improved. 
     In addition, the refrigerant separated from the mixed fluid is discharged to the outside of the electric compressor  1  through the exhaust port  122  positioned above the cylinder  610 . Further, the oil separated from the mixed fluid is discharged through the oil discharge port  616  located at the lower side of the cylinder  610 . 
     Therefore, the refrigerant and the fluid separated from the mixed fluid may be effectively discharged from the oil separating apparatus  600  without a separate member according to the respective densities. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims.