Patent Publication Number: US-2020300245-A1

Title: Motor-operated compressor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of earlier filing date and the right of priority to Korean Patent Application No. 10-2019-0032498, filed on Mar. 21, 2019, the contents of which are incorporated by reference herein in their entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a compressor, and more particularly, a motor-operated compressor employing a scroll compression method and driven by a motor. 
     2. Description of the Related Art 
     Compressors are classified into a mechanical type driven by an engine and a motor-operated type driven by a motor. A motor-operated compressor typically employs a scroll compression method suitable for a high compression ratio operation among various compression methods. 
     In the scroll type motor-operated compressor (hereinafter, referred to as “motor-operated compressor”), a motor unit configured as a drive motor is installed in a hermetic casing, and a compression unit configured by a fixed scroll and an orbiting scroll is disposed at one side of the motor unit. The motor unit and the compression unit are connected to each other by a rotating shaft so that a rotational force of the motor unit is transferred to the compression unit. The rotational force transmitted to the compression unit allows a fluid, such a refrigerant, to be compressed. 
     The motor-operated compressor can be installed in an electric vehicle to create a refrigeration cycle. Electric cars have a lower power output than engine-powered vehicles, and thus, it is important to reduce weight of automotive components as possible. Accordingly, a small and lightweight motor-operated compressor is more advantageous in terms of reducing an installation space and weight reduction. 
     However, in the related art motor-operated compressor, as a fixed scroll and an orbiting scroll constituting a compression unit is supported by a frame, there is a limitation in reducing a size and weight of the compressor. Korean Patent Laid-Open Publication No. 10-2014-0136796 (hereinafter, “Patent Document 1”), which is hereby incorporated by reference, discloses a compressor in which a frame that supports a fixed scroll and an orbiting scroll is excluded or removed by using the fixed scroll to serve as the frame. However, the compressor disclosed in Patent Document 1 is mainly developed for an air conditioning system, and a vertical-type type compressor in which a motor unit and a compression unit are arranged in a vertical direction. A compressor used in vehicles is, generally, a horizontal-type compressor in which a motor unit and a compression unit are arranged in a horizontal direction. Accordingly, the compressor of Patent Document 1 is not suitable for the vehicles. Thus, there is a need to develop a horizontal and frame scroll type motor-operated compressor applicable to the vehicles. 
     SUMMARY 
     Embodiments disclosed herein provide a motor-operated compressor, capable of reducing the number of components and manufacturing costs by employing a horizontal type compressor equipped with a frame scroll, thereby achieving the small and lightweight motor-operated compressor. 
     Embodiments disclosed herein further provide a motor-operated compressor, capable of reducing friction loss and abrasion by ensuring a sufficient oil storage space for oil separated from a refrigerant discharged from a compression chamber while employing a horizontal type compressor equipped with a frame scroll. 
     Embodiments disclosed herein also provide a motor-operated compressor, capable of securing a sufficient oil storage space while facilitating processing (or fabrication) of a rear housing defining the storage space. 
     Embodiments disclosed herein provide a motor-operated compressor that may include a frame scroll disposed to face a drive motor, an orbiting scroll engaged with the frame scroll to form a compression space, and a housing deposed at an opposite side of the frame scroll to support the orbiting scroll. The housing may be provided with a discharge space, an oil storage space having an annular shape formed along a circumference of the discharge space, and an oil separation space formed between the discharge space and the oil storage space. 
     Embodiments disclosed herein may further provide a motor-operated compressor that may include a frame scroll, an orbiting scroll, and a rear housing sequentially based on a drive motor. A recessed oil storage space may be provided at one side surface of the rear housing that faces the orbiting scroll. The rotating scroll may be provided with an oil passage communicating with the oil storage space. 
     Embodiments disclosed herein may further provide a motor-operated compressor that may include a thrust plate provided between an orbiting scroll and a housing that supports the orbiting scroll in a direction to a frame scroll. A hermetically sealed space may be provided at both side surfaces of the thrust plate, respectively. The hermetically sealed space may be separated from an inner space and a discharge space of the housing. A pressure reducing member may be provided between the hermetically sealed space and the discharge space. 
     Embodiments disclosed herein may further provide a motor-operated compressor that may include a main housing having a suction space, a motor unit disposed at the suction space of the main housing, a rotating shaft coupled to the motor unit, a fixed scroll coupled to the main housing to support the rotating shaft, and provided with an inlet port communicating with the suction space, an orbiting scroll coupled to the rotating shaft to perform an orbiting motion with respect to the fixed scroll, forming a compression space, and provided with a discharge port, and a rear housing coupled to the main housing. 
     The rear housing may be provided with a discharge space communicating with the discharge port of the orbiting scroll formed at a central portion of a surface facing the orbiting scroll, an oil storage space formed at an edge portion of the surface facing the orbiting scroll, and an oil return passage that guides oil separated in the discharge space to the oil storage space. 
     The oil storage space may be formed such that a surface facing the orbiting scroll is opened. 
     A first annular-shaped support surface may be provided at an inner circumferential side of the oil storage space, and the first annular-shaped support surface may be provided with a first sealing member that seals between the oil storage space and the discharge space. 
     In addition, a second annular-shaped support surface may be provided at an outer circumferential side of the oil storage space, and the second annular-shaped support surface may be provided with a second sealing member that seals between the oil storage space and the suction space. 
     At least one oil storage space partitioning protrusion that connects between the first annular-shaped support surface and the second annular-shaped support surface may be provided therebetween. The oil storage space partitioning protrusion may have an axial height lower than an axial height of the first annular-shaped support surface and the second annular-shaped support surface. 
     Further, at least one oil storage space partitioning protrusion that connects between the first annular-shaped support surface and the second annular-shaped support surface may be provided therebetween. The oil storage space partitioning protrusion may be provided with a space communication groove. 
     Furthermore, at least one oil storage space partitioning protrusion that connects between the first annular-shaped support surface and the second annular-shaped support surface may be provided therebetween. The oil storage space partitioning protrusion may be provided with an anti-rotation pin rotatably inserted into an anti-rotation ring provided at the orbiting scroll, so as to prevent rotation of the orbiting scroll. 
     In addition, the oil storage space may be formed in an annular shape, and be provided with a plurality of pin fixing protrusions formed along a circumferential direction with a predetermined distance therebetween. Each of the plurality of pin fixing protrusions may be provided with an anti-rotation pin rotatably inserted into an anti-rotation ring provided at the orbiting scroll. 
     Here, an outlet end of the oil return passage may communicate with the oil storage space at a position lower than a position of the discharge space. 
     In addition, the outlet end of the oil return passage may be provided on a side wall surface of the oil storage space to form a return passage forming protrusion axially protruding to a predetermined height. The return passage forming protrusion may be provided with a flow controller configured to control a flow rate of oil passing through the oil return passage. 
     The orbiting scroll may be provided with an oil guide passage, and one end of the oil guide passage may communicate with the oil storage space of the rear housing. 
     In addition, a central portion of the orbiting scroll may be provided with a rotating shaft coupling portion to which the rotating shaft is coupled. Another end of the oil guide passage may communicate with the rotating shaft coupling portion. 
     An oil supply passage may be provided at an end portion of the rotating shaft inserted into the rotating shaft coupling portion, so as to communicate with the oil guide passage. The oil supply passage may include an oil supply groove formed at the end portion of the rotating shaft in an axial direction, and a plurality of oil supply holes penetrating toward the rotating shaft coupling portion and the fixed scroll from the oil supply groove. 
     The oil guide passage may be located higher than the oil return passage. 
     The orbiting scroll may be further provided with a low-pressure side oil supply passage communicating with the oil guide passage. The low-pressure side oil supply passage may include a low-pressure side oil supply hole axially penetrating through an orbiting wrap provided at the orbiting scroll. 
     An oil supply communication groove may be further provided at an end portion of the orbiting wrap facing the fixed scroll. The oil supply communication groove may be formed to be connected to a side wall surface of the orbiting wrap from an end portion of the low-pressure side oil supply hole. 
     Here, a thrust plate may be provided between the orbiting scroll and the rear housing. A plurality of scroll-side sealing members may be provided between the thrust plate and the orbiting scroll to be spaced apart by predetermined intervals in a radial direction. A plurality of housing-side sealing members may be provided between the thrust plate and the rear housing in the radial direction with the oil storage space interposed therebetween. 
     The thrust plate may be provided with a plurality of pin holes formed along a circumferential direction so that an anti-rotation pin that prevents rotation of the orbiting scroll is penetratingly coupled. At least one communication hole may be formed to provide communication between the plurality of scroll-side sealing members and the plurality of housing-side sealing members. 
     Embodiments disclosed herein may further provide a motor-operated compressor that may include a first housing having a suction space, a motor unit provided at one end of the first housing, a rotating shaft coupled to the motor unit to be rotatable, a first scroll disposed at the suction space of the first housing and provided at another end of the first housing to face the motor unit, coupled to the first housing to support the rotating shaft, and provided with an inlet port communicating with the suction space, a second scroll coupled to the rotating shaft to perform an orbiting motion with respect to the first scroll, forming a compression space at a first side surface thereof facing the first scroll, and provided with a discharge port, and a second housing disposed to face a second side surface opposite to the first side surface of the second scroll so as to be coupled to the first housing. 
     The second housing may be provided with a discharge space communicating with the discharge port of the second scroll formed at a central portion of a surface facing the second scroll, an oil separation space formed at one side of the discharge space to communicate with the discharge space, and an oil storage space formed at an edge portion of the surface facing the second scroll to communicate with the oil separation space. 
     The second scroll may be provided with an oil guide passage communicating with the oil storage space of the second housing. The rotating shaft may be provided with an oil supply passage communicating with the oil guide passage, so as to guide oil in the oil storage space to a bearing surface that supports the rotating shaft. 
     In a motor-operated compressor according embodiments, a horizontal type compressor equipped with a frame scroll may be employed to reduce the number of components and manufacturing costs, thereby achieving the small and lightweight motor-operated compressor. 
     In addition, in the motor-operated compressor according embodiments, a discharge space for accommodating a refrigerant discharged from a compression chamber, and an oil storage space formed at the adjacent to the discharge space to store oil separated from the refrigerant discharged from the compression chamber are provided, thereby sufficiently securing the oil storage space. This allows oil in the oil storage space to be quickly supplied to a portion or part requiring lubrication. As a result, friction loss or abrasion caused by an insufficient amount of oil can be reduced. 
     Further, in the motor-operated compressor according embodiments, the oil storage space may be formed to be opened to one side surface of a rear housing, allowing the rear housing to be easily fabricated (or processed) and manufacturing costs of the rear housing to be reduced. 
     In addition, in the motor-operated compressor according embodiments, as an outlet end of an oil return passage that provides communication between an oil separation space and the oil storage space is formed through a side wall surface of the oil storage space at a position lower than the discharge space, oil separated from the oil separation space can be quickly introduced into the oil storage space. 
     Furthermore, in the motor-operated compressor according embodiments, a plurality of scroll-side sealing members may be provided between a thrust plate and an orbiting scroll to be spaced apart by predetermined intervals in a radial direction, and a plurality of housing-side sealing members may be provided in the radial direction with the oil storage space interposed therebetween. Accordingly, the oil storage space may be sealed with respect to each of a discharge pressure space and a suction pressure space, and thus the oil storage space can maintain an intermediate pressure. As a result, oil supplied can be maintained at an intermediate pressure, thereby preventing performance of the compressor from being degraded or lowered. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating an outer appearance of a motor-operated compressor according to an embodiment; 
         FIG. 2  is an exploded perspective view of the motor-operated compressor of  FIG. 1 ; 
         FIG. 3  is an assembled cross-sectional view illustrating an inside of the motor-operated compressor of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view illustrating a coupled state of a fixed scroll and an orbiting scroll in a compression unit according to an embodiment; 
         FIG. 5  is an enlarged cross-sectional view illustrating a portion with respect to a rotating shaft in  FIG. 3 ; 
         FIG. 6  is a perspective view of the orbiting scroll according to an embodiment, viewed from the rear; 
         FIG. 7  is a cross-sectional view taken along line “V-V” of  FIG. 6 ; 
         FIG. 8  is a perspective view of a rear housing according to an embodiment, viewed from the front; 
         FIG. 9  is a planar view of the rear housing of  FIG. 8 , viewed from the front; 
         FIG. 10  is a cross-sectional view taken along line “VI-VI” of  FIG. 9 ; 
         FIG. 11  is a planar view of an oil storage space according to another embodiment; 
         FIG. 12  is a cross-sectional view of an oil guide passage according to another embodiment; 
         FIG. 13  is an enlarged cross-sectional view illustrating a portion of the motor-operated compressor according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Description will now be given in detail of a motor-operated compressor according to exemplary embodiments disclosed herein, with reference to the accompanying drawings. 
       FIG. 1  is a perspective view illustrating an outer appearance of a motor-operated compressor according to an embodiment. 
     Referring to  FIG. 1 , a motor-operated compressor  100  according to this embodiment may include a compression module  101  and an inverter module  102 . The compression module  101  refers to a set of parts (or components) for compressing a fluid such as a refrigerant, and the inverter module  102  refers to a set of parts for controlling driving of the compression module  101 . The inverter module  102  may be coupled to a front side of the compression module  101 . Hereinafter, a side where the inverter module  102  is installed is referred to as a “front side”, and a side where the compression module  101  is installed is referred to as a “rear side”, respectively. As a fluid (hereinafter, “refrigerant”) to be compressed or pressurized is introduced into an inlet port  111  and is then discharged to an exhaust port  126 , the inverter module  102  disposed close to the inlet port  111  should be coupled to the front side of the compression module  101 , which is more suitable for cooling the inverter module  101 . 
     The outer appearance of the compression module  101  may be defined by a main housing  110 , which is a first housing, and a rear housing  120 , which is a second housing. For example, the main housing  110  may have a closed front end and an opened rear end, and the rear housing  120  may have an opened front end and a closed rear end. Accordingly, the rear end of the main housing  110  and the front end of the rear housing  120  may communicate with each other to form a sealed casing for the compression module  101 . 
       FIG. 2  is an exploded perspective view of the motor-operated compressor of  FIG. 1 , and  FIG. 3  is an assembled cross-sectional view illustrating an inside of the motor-operated compressor of  FIG. 1 . 
     Referring to these drawings, the main housing  110  may have a hollow cylindrical shape, a hollow polygonal cylinder shape, or the like. The main housing  110  may be disposed to extend toward a horizontal direction. The main housing  110  may surround or cover a motor unit  130  to be described hereinafter. One axial end of the main housing  110  may be closed, and another axial end of the main housing  110  may be open. 
     The inlet port  111  may be formed on an outer circumferential surface of the main housing  110 . The inlet port  111  may provide a flow path that supplies a refrigerant (e.g., R134a, R32, CO2, etc.) to an inner space of the compression module  101 . 
     A first scroll support surface  112  that axially supports a support protrusion  143  of a fixed scroll  140  to be described hereinafter may be provided on an inner circumferential surface of the rear end of the main housing  110 . The first scroll support surface  112  may be formed in a stepped manner to have an arc shape, or may be formed in a stepped manner to have an annular shape. The first scroll support surface  112  may be provided with a plurality of coupling grooves  112   a  formed along a circumferential direction with a predetermined distance therebetween so as to correspond to a bolt passing groove  143   c  of the fixed scroll  140  and a coupling hole  120   b  of the rear housing  120 , which will be described hereinafter. 
     The rear housing  120  may be coupled to the rear end of the main housing  110 . The rear housing  120  may cover the rear end of the main housing  110 . The exhaust port  126  may be provided at the rear housing  120 , and an oil separator  123   a  may be installed at the exhaust port  126 . 
     In addition, the rear housing  120  may be disposed to face a rear surface of an orbiting scroll  150  to be described hereinafter, so as to form a compression unit accommodating space  121 , a discharge space  122 , an oil separation space  123 , and an oil storage space  124 , which are important features of the present disclosure, so this will be described in detail later together with relevant members. 
     Referring back to  FIGS. 2 and 3 , as for the compression module  101 , the motor unit  130  (drive unit or drive motor) and a compression unit  105  may be axially disposed in an inner space of the main housing  110  defining a portion or part of the casing, and the motor unit  130  and the compression unit  105  may be connected by a rotating shaft  160 . The motor unit  130  may be located at a front side of the main housing  110 , and the compression unit  105  may be located at a rear side of the main housing  110 . 
     Here, as the inlet port  111  is provided at the main housing  110 , the inner space of the main housing  110  may form a suction space S 1 , and thus, the motor unit  130  and the compression unit  105  are located at the suction space S 1  forming a suction pressure. Therefore, the suction space S 1  may also be referred to as a motor chamber. 
     The motor unit  130  may be configured to generate a driving force required for the orbiting scroll  150  of the compression unit  105  to perform an orbiting motion. The motor unit  130  may also be referred to as a drive motor, and configured as an electric motor. 
     The motor unit  130 , or the drive motor may include a stator  131  and a rotor  132 . The stator  131  may be fixedly inserted into an inner circumferential surface of the main housing  110  in a shrink-fitting manner (or hot press fitting). Alternatively, the stator  131  may be fixed by welding after insertion or may be fixed by using another fixing member. 
     The rotor  132  may be disposed inside the stator  131  in a rotatable manner. When an electric power is applied to the stator  131 , the rotor  132  is rotated by electromagnetic interaction with the stator  131 . 
     The rotating shaft  160  may be coupled to a center of the rotor  132 . An eccentric portion  164  may be provided at the rotating shaft  160  to be eccentrically coupled to the orbiting scroll  150 . This allows a rotational force of the drive motor to be transferred to the orbiting scroll  150  by the rotating shaft  60 . This will be described again later since the rotating shaft  160  is related to the present disclosure. 
       FIG. 4  is a cross-sectional view illustrating a coupled state of a fixed scroll and an orbiting scroll in a compression unit according to an embodiment, and  FIG. 5  is an enlarged cross-sectional view illustrating a portion with respect to a rotating shaft in  FIG. 3 . 
     Referring to  FIG. 4 , the compression unit  105  is configured to compress a refrigerant. The compression unit  105  may include the fixed scroll  140  defining the frame scroll (a frame scroll and the fixed scroll are the same member, so hereinafter the terms frame scroll and fixed scroll may be used interchangeably) and the orbiting scroll  150 . The compression unit  105  may be defined by the fixed scroll  140  and the orbiting scroll  150 . The fixed scroll  140  and the orbiting scroll  150  may also be referred to as a first scroll and a second scroll, respectively. 
     The fixed scroll  140  and the orbiting scroll  150  may be coupled to each other to form a pair of compression chambers. As the orbiting scroll  150  performs an orbiting motion, a volume of the compression chambers is repeatedly changed, and a refrigerant is compressed in the compression chambers, accordingly. 
     The fixed scroll and the orbiting scroll will be described in detail with reference to  FIG. 3 . 
     The fixed scroll  140  may be located relatively close to the motor unit  130 , and the orbiting scroll  150  may be located relatively far from the motor unit  130 . The fixed scroll  140  may be disposed between the orbiting scroll  150  and the main housing  110  in an axial direction. The orbiting scroll  150  may be disposed between the fixed scroll  140  and the rear housing  120  in the axial direction. 
     The fixed scroll  140  may include a fixed end plate  141  and a fixed wrap  142 . The fixed end plate  141  may have a substantially disk shape. A plurality of support protrusions  143  may be formed on an outer circumferential surface of the fixed end plate  141  along a circumferential direction with a predetermined distance therebetween. The bolt passing groove  143   c  through which a coupling bolt described hereinafter passes may be provided between the support protrusions  143 . Accordingly, an edge of a first side surface  143   a  of the support protrusion  143  facing the drive motor may be axially supported with respect to the front side by the first scroll support surface  112  provided on the inner circumferential surface of the main housing  110 . A coupling bolt B passing through the coupling hole  120   b  of the rear housing  120  and the bolt passing groove  143   c  of the fixed scroll  140  may be fastened to the coupling groove  112   a , so that the main housing  110  of the fixed scroll  140  and the rear housing  120  are coupled to each other. 
     Of both side surfaces of the support protrusion  143 , a second side surface  143   b  facing the orbiting scroll  150  may be in close contact with an open end surface  120   a  of the rear housing  120 . Accordingly, the first side surface  143   a  of the support protrusion  143  of the fixed scroll  140  may be in close contact with the first scroll support surface  112  of the main housing  110  to be axially supported, and the second side surface  143   b  of the support protrusion  143  of the fixed scroll  140  may be in close contact with the opened end surface  120   a  of the rear housing  120  to be axially supported. 
     In addition, a suction port  145  may be formed through the support protrusion  143  so that the suction space S 1  and a suction chamber V 1  communicate with each other. Accordingly, a height (i.e. radial extent) of the first scroll support surface  112  may be preferably formed to an extent that does not cover the suction port  145 . 
     Meanwhile, a scroll bearing portion  146  axially extending toward the drive motor may be provided at a central portion of the fixed end plate  141 , and a rotating shaft accommodating portion  147  may be formed through the scroll bearing portion  146  in the axial direction. 
     A main bearing  171  (see  FIG. 5 ) may be fixedly inserted into an inner circumferential surface of the rotating shaft bearing portion  147 , so that a main bearing portion  162  of the rotating shaft  160  is inserted and radially supported. The main bearing  171  may be configured as a ball bearing. In this embodiment, however, a bush bearing is employed to reduce manufacturing costs. 
     A sealing member (not shown) may be provided at a front end of the rotating shaft accommodating portion  147 , so as to provide a seal between the rotating shaft  160  and the fixed scroll  140 . Accordingly, as for the rotating shaft  160 , the main bearing portion  162  provided at a rear side with respect to the rotor  132  of the drive motor (motor unit  130 ) may be radially supported by the fixed scroll  140 . 
     A sub bearing portion  163  formed at a front side of the rotating shaft  160  may be supported by a sub bearing  172  provided at a front side surface of the main housing  110 . The sub bearing  172 , configured as a ball bearing, may be inserted into a shaft support portion  113  provided on a front inner surface of the main housing  110 . As the sub bearing  172  is implemented as the ball bearing, the rotating shaft  160  may be radially and axially supported by the sub bearing  172 . 
     Referring to  FIGS. 3 and 4 , the fixed wrap  142  may protrude toward the orbiting scroll  150  from a second side surface  141   b  of the fixed end plate  141  facing the orbiting scroll  150 . The fixed wrap  142  may have an involute shape. In this embodiment, however, the fixed wrap  142  may have a non-volute shape as the rotating shaft  160  penetrates through the fixed scroll  140  and is inserted into and coupled to the orbiting scroll  150 . The shape of the fixed wrap will be discussed later together with an orbiting wrap. 
       FIG. 6  is a perspective view of the orbiting scroll according to an embodiment, viewed from the rear, and  FIG. 7  is a cross-sectional view taken along line “V-V” of  FIG. 6 . 
     Referring back to  FIG. 3 , the orbiting scroll  150  may be disposed to face the fixed scroll  140 . The orbiting scroll  150  may be coupled to the eccentric portion  164  (see  FIG. 5 ) provided at a rear end of the rotating shaft  160 . Accordingly, the orbiting scroll  150  may be eccentrically coupled to the rotating shaft  160 . The orbiting scroll  150  may receive a rotational force from the eccentric portion  164  and may perform an orbiting motion by an anti-rotation mechanism  190 . 
     Referring to  FIGS. 3 to 7 , the orbiting scroll  150  may include an orbiting end plate  151 , an orbiting wrap  152 , and a rotating shaft coupling portion  153 . 
     The orbiting end plate  151  may have a disk shape corresponding to the fixed end plate  141 . If the fixed end plate  141  has a cross section that correspond to a disk (disc), then the orbiting end plate  151  has a disk-shaped cross section. 
     Of both axial side surfaces of the orbiting end plate  151 , when a surface facing the fixed scroll  140  is a first side surface  151   a  and a surface facing the rear housing  120  is a second side surface  151   b , the orbiting wrap  152  may be provided on the first side surface  151   a , and an anti-rotation groove  154  may be formed on the second side surface  151   b.    
     The orbiting wrap  152  may protrude from the first side surface  151   a  of the orbiting end plate  151  toward the fixed scroll  140  into an involute curve shape, an Archimedean spiral shape, or a logarithmic spiral shape. 
     However, in this embodiment, the orbiting wrap  152  together with the fixed wrap  142  may be formed in a non-involute shape. This is to reduce a pressure difference between compression pockets formed at an outer side with respect to the fixed wrap  142  and formed at an inner side with respect to the fixed wrap  142 , as the rotating shaft  160  penetrates through the fixed scroll  140  to be coupled to the orbiting wrap  152  of the orbiting scroll  150  in a radially overlapping manner. For example, as illustrated in  FIG. 4 , the orbiting wrap  152  according to this embodiment may be provided with a protruding portion  153   a  formed at an end portion of a discharge side constituting the rotating shaft coupling portion  153 , so as to extend a crank angle (compression angle) of the inner side compression pocket. This allows a compression period (or cycle) to be extended. Further, the pressure difference between the opposite compression pockets may be minimized by increasing a compression ratio of the inner side compression pocket. 
     The rotating shaft coupling portion  153  may be provided at a central portion of the orbiting end plate  151 . The rotating shaft coupling portion  153  may protrude toward the fixed scroll  140  from the first side surface  151   a  of the orbiting end plate  151 . The rotating shaft coupling portion  153  may be provided at a position corresponding to an involute base circle defining the orbiting wrap  152 . Accordingly, the rotating shaft coupling portion  153  may form the innermost part or portion of the orbiting wrap  152 . 
     The rotating shaft coupling portion  153  may have a hollow cylindrical shape so as to accommodate the eccentric portion  164  of the rotating shaft  160  therein. The rotating shaft coupling portion  153  may be formed to cover or surround the eccentric portion  164  of the rotating shaft  160 . 
     The rotating shaft coupling portion  153  of the orbiting scroll  150  may have one open side. For example, the rotating shaft coupling portion  153  of the orbiting scroll  150  may be open toward the fixed scroll  140 , but a rear surface thereof opposite to the open side may be blocked by the orbiting end plate  151 . Accordingly, the eccentric portion  164  of the rotating shaft  160  may be inserted into the rotating shaft coupling portion  153  of the orbiting scroll  150 , but may not penetrate through the orbiting end plate  151 . 
     Referring to  FIGS. 6 and 7 , a plurality of anti-rotation grooves  154 , a plurality of sealing grooves  155   a  and  155   b , and a discharge guide groove  156  are provided on the second side surface  151   b  of the orbiting end plate  151 . 
     The plurality of anti-rotation grooves (precisely, anti-rotation rings)  154  and an anti-rotation pin  192  (see  FIG. 11 ) to be described hereinafter defining the anti-rotation mechanism  190  may be provided to suppress a rotary motion of the orbiting scroll  150 . The plurality of anti-rotation grooves  154  may be disposed to be spaced apart by predetermined intervals along a circumferential direction. The plurality of anti-rotation grooves  154  may be formed to correspond to a plurality of anti-rotation pins  192 . An anti-rotation ring  191  may be inserted and coupled to each of the plurality of anti-rotation grooves  154 , respectively. Accordingly, the anti-rotation pin  192  may be rotatably inserted into the anti-rotation ring  191 . 
     Sealing members  181 ,  182  may be inserted into the plurality of sealing grooves  155   a  and  155   b , respectively, so as to provide a seal between the orbiting scroll  150  and a thrust plate  180  to be described hereinafter. This is to form a rear-side intermediate pressure space S 22  so that the oil storage space  124  described hereinafter maintains an intermediate pressure. The plurality of sealing grooves  155   a  and  155   b  may be disposed radially inward and outward, respectively, with the plurality of anti-rotation grooves  154  interposed therebetween. The sealing groove disposed radially inward may be referred to as a scroll-side first sealing groove  155   a  and the sealing groove disposed radially outward may be referred to as a scroll-side second sealing groove  155   b.    
     For example, the scroll-side first sealing groove  155   a  may be provided adjacent to a central portion of the second side surface  151   b  of the orbiting end plate  151 , and the scroll-side second sealing groove  155   b  may be provided adjacent to an edge portion of the second side surface  151   b  of the orbiting end plate  151 . A scroll-side first sealing member  181  inserted into the scroll-side first sealing groove  155   a  may have a smaller diameter than a scroll-side second sealing member  182  inserted into the scroll-side second sealing groove  155   b . Accordingly, the rear-side intermediate pressure space S 22  may be separated from the discharge space  122  by the scroll-side first sealing member  181 , and may be separated from the suction space S 1  by the scroll-side second sealing member  182 . 
     In addition, the scroll-side first sealing groove  155   a  and the scroll-side second sealing groove  155   b  may be eccentrically disposed with respect to each other. In more detail, the scroll-side second sealing groove  155   b  may be substantially coaxial with an axial center Oc (see  FIG. 11 ) of the rotating shaft  160 , but the scroll-side first sealing groove  155   a  may be eccentrically formed from the axial center Od (see  FIG. 11 ) of the rotating shaft  160 . This is because as the motor-operated compressor according to this embodiment has a shaft through structure, a discharge port  157  to be described hereinafter may be eccentrically disposed from the axial center. 
     The discharge guide groove  156  may be engraved or depressed from the second side surface  151   b  of the orbiting end plate  151  by a predetermined depth. Discharge guide groove  156  may be formed at a central portion of the second side surface  151   b  of the orbiting plate  151 . As described above, as the discharge port  157  is eccentrically disposed from the axial center Oc, the discharge guide groove  156  may also be eccentrically disposed from the axial center Oc. The scroll-side first sealing groove  155   a  (see  FIG. 6 ) may be provided on an inner circumferential surface of the discharge guide groove  156  in a stepped manner. 
     In addition, the discharge port  157  may be provided in the discharge guide groove  156 . The discharge port  157  may penetrate between the first side surface  151   a  and the second side surface  151   b  of the orbiting end plate  151 . An end portion of the discharge port  157  may be provided with a check valve  158  to open and close the discharge port  157 , which acts a kind of a discharge valve. 
     The orbiting end plate  151  may be provided with an oil guide passage  159  that guides oil introduced into the oil storage space  124  of the rear housing  120  to an oil supply passage  165  of the rotating shaft  160 . This is a feature of the present disclosure, so this will be discussed later together with the rear housing. 
     Referring back to  FIGS. 2 and 3 , the rotating shaft  160  may be connected to the motor unit  130  and the orbiting scroll  150 , respectively, so that a driving force generated in the motor unit  130  is transferred to the orbiting scroll  150 . To this end, the rotating shaft  160  may extend from the front to the rear of the motor-operated compressor  100 . A direction to which the rotating shaft  160  extends may be an axial direction of the rotating shaft  160 . The rotating shaft  160  may be fixed to the rotor  132  in a shrink-fitting manner (or hot press fitting). 
     Referring to  FIG. 5 , the rotating shaft  160  may include a motor coupling portion  161 , the main bearing portion  162 , the sub bearing portion  163 , and the eccentric portion  164 . 
     The motor coupling portion  161  may be coupled through the center of the rotor  132 . 
     The main bearing portion  162  corresponds to a rear side of the motor coupling portion  161 , and the sub bearing portion  163  corresponds to a front side of the motor coupling portion  161 . Accordingly, the main bearing portion  162  and the sub bearing portion  163  may axially extend from the motor coupling portion  161  to directions opposite from each other. Each of the main bearing portion  162  and the sub bearing portion  163  may have an outer diameter different from a diameter of the motor coupling portion  161 . A center of the main bearing portion  162  and a center of the sub bearing portion  163  may coincide with a center of the motor coupling portion  161 , respectively. 
     The main bearing portion  162  may be inserted to axially penetrate through the rotating shaft accommodating portion  147  of the fixed scroll  140  to be described hereinafter. The main bearing  171  implemented as a bush bearing may be coupled to the rotating shaft accommodating portion  147 . Accordingly, the main bearing portion  162  may be radially supported by the main bearing  171  in a rotatable manner. 
     The sub bearing portion  163  may be coupled to the shaft support portion  113  provided on a front surface of the main housing  110 . The sub-bearing  172  implemented as a ball bearing may be coupled to the shaft support portion  113 . Accordingly, the sub bearing portion  163  may be radially and axially supported by the sub bearing  172  in a rotatable manner. 
     The eccentric portion  164  is a portion that corresponds to a rear side of the main bearing portion  162 . The eccentric portion  164  may axially extend from the main bearing portion  162 . The eccentric portion  164  may have an outer diameter smaller than the outer diameter of the main bearing portion  162 . 
     A center of the eccentric portion  164  may be eccentrically disposed with respect to the center of the main bearing portion  162 . Referring to  FIG. 4 , a center Oe of the eccentric portion  164  may be eccentrically disposed from the center of the motor coupling portion  161  in the axial direction of the rotating shaft  160  or from the axial center Oc of the rotating shaft  160  which is coaxial with the center of the motor coupling portion  161 . The eccentric portion  164  may be formed at the rear end of the rotating shaft  160  to be inserted into the rotating shaft coupling portion  153  of the orbiting scroll  150 . 
     The oil supply passage  165  may be provided in the rotating shaft  160  so as to guide oil introduced into the rotating shaft coupling portion  154  of the orbiting scroll  150  to the main bearing portion  162  and the eccentric portion  164 . The oil supply passage  165  may include an oil supply groove  165   a  and a plurality of oil supply holes  165   b  and  165   c.    
     The oil supply groove  165   a  may be formed as a groove recessed from the rear end of the rotating shaft  160  to a predetermined depth, and the oil supply holes  165   b ,  165   c  may be implemented as holes, respectively, each penetrating from the oil supply groove  165   a  to an outer circumferential surface of the rotating shaft  160 , namely, to an outer circumferential surface of the main bearing portion  162  and an outer circumferential surface of the eccentric portion  164 , respectively. The oil supply hole formed through the main bearing portion  162  may be referred to as a first oil supply hole  165   b , and the oil supply hole formed through the eccentric portion  164  may be referred to as a second oil supply hole  165   c.    
     The first oil supply hole  165   b  and the second oil supply hole  165   c  may have the same inner diameter and may penetrate in the same direction. In some cases, however, an inner diameter of the second oil supply hole  165   c  may be larger than an inner diameter of the first oil supply hole  165   b . This may allow more oil to be supplied to the eccentric portion  164  than the main bearing portion  162 , and thus, oil may be supplied to the compression chambers more quickly. 
     Meanwhile, as described above, the casing according to this embodiment may be configured as the main housing  110  and the rear housing  120 . The fixed scroll  140  provided between the main housing  110  and the rear housing  120  may be axially supported to be fixed. 
       FIG. 8  is a perspective view of a rear housing according to an embodiment, viewed from the front,  FIG. 9  is a planar view of the rear housing of  FIG. 8 , viewed from the front, and  FIG. 10  is a cross-sectional view taken along line “VI-VI” of  FIG. 9 . 
     Referring to these drawings, the rear housing  120  may be coupled to the rear end of the main housing  110  while axially supporting the fixed scroll  140 . Accordingly, the front end of the rear housing  120 , namely, an open end surface  120   a  of the rear housing  120  may be wider (or larger) than a width of the rear end (opened end surface) of the main housing  110 , so as to support both the rear end of the main housing  110  and the support protrusion  143  of the fixed scroll  140 . 
     In addition, the open end of the rear housing  120  may be provided with a plurality of coupling holes  120   b  and a bolt accommodating grooves  120   c , respectively, formed along an inner circumferential surface of the rear housing  120 , so that the coupling bolt B penetrates therethrough. A gasket or an O-ring may be provided on the open end surface  120   a  of the rear housing  120  to be coupled to the main housing  110 , thereby enhancing a sealing effect. The coupling hole  120   b  and the bolt accommodating groove  120   c  may be formed in line with the bolt passing groove  143   c  provided between the support protrusions  143  of the fixed scroll  140 , and the coupling groove  112   a  of the main housing  110 . 
     The inner space of the rear housing  120  may include sequentially the compression unit accommodating space  121 , the discharge space  122 , the oil separation space  123 , and the oil storage space  124  starting from the compression chamber V in a refrigerant flowing direction. An inner diameter of the compression unit accommodating space  121  may be wider (or larger) than an inner diameter of the discharge space  122 . Accordingly, a second scroll support surface  125  may be provided between the compression unit accommodating space  121  and the discharge space  122  in a stepped manner, so as to support the rear surface of the orbiting scroll  150 . An outer circumference and an inner circumference of the second scroll support surface  125  may extend to the compression unit accommodating space  121  and the discharge space  122 , respectively. 
     The second scroll support surface  125  may be provided with a plurality of sealing grooves  125   a  and  125   b  spaced apart from each other in a radial direction. For example, a housing-side first sealing groove  125   a  may be provided at a central portion of the second scroll support surface  125  so that the housing-side first sealing member  183  (see  FIG. 10 ) that comes into close contact with a central portion of a rear surface of the thrust plate  180  is inserted, and a housing-side second sealing groove  125   b  may be provided at an edge portion of the second scroll support surface  125  so that the housing-side second sealing member  184  (see  FIG. 10 ) that comes into close contact with an edge portion of the rear surface of the thrust plate  180  is inserted. 
     The rear-side intermediate pressure space S 22  communicating with a front-side intermediate pressure space S 21  provided between the scroll-side first sealing member  181  and the scroll-side second sealing member  182  may be provided between the housing-side first sealing member  183  and the housing-side second sealing member  184 . The front-side intermediate pressure space S 21  and the rear-side intermediate pressure space S 22  may communicate with each other through a pin hole  180   a  formed at the thrust plate  180  or an oil communication hole  180   b.    
     The discharge space  122  may be provided inside the housing-side first sealing member  183 . The discharge space  122  may be further recessed toward the rear side than the compression unit accommodating space  121 . The discharge space  122  may be disposed to face the discharge guide groove  156  of the orbiting scroll  150  to communicate with the discharge port  157 . As shown in  FIG. 9 , a center Od of the discharge space  122  may be eccentrically disposed with respect to a center of the rear housing  120 , namely, the axial center Oc of the rotating shaft  165 , like the discharge guide groove  156 . The housing-side first sealing member  183  may be eccentrically disposed with respect to the housing-side second sealing member  184 . Accordingly, the rear-side intermediate pressure space S 22  to be described hereinafter may be disposed eccentrically with respect to the axial center Oc. This is also the case for the front-side intermediate pressure space S 21 . 
     Referring to  FIGS. 8 and 10 , the discharge space  122  may be formed in a cylindrical shape having a closed rear surface on which the oil separation space  123  is provided. Accordingly, the rear surface of the discharge space  122  may slightly protrude forward to secure the oil separation space  123 . An oil separation communication hole  122   a  may be provided at the rear surface of the discharge space  122  to communicate with the oil separation space  123 . 
     The oil separation space  123  may be formed in a vertical direction or in a direction slightly inclined with respect to the vertical direction. The oil separator  123   a  may be installed in the oil separation space  123  to separate oil from a refrigerant introduced into the oil separation space  123 . After separation, the refrigerant flows into a refrigeration cycle via the exhaust port  126  formed through an upper end of the oil separation space  123 , while the oil in a mist state flows into the oil storage space  124  via an oil return (or recovery) passage  127  formed though a lower end of the oil separation space  123 . 
     The oil storage space  124  may be provided between the housing-side first sealing member  183  and the housing-side second sealing member  184 . That is, the oil storage space  124  may be formed on the second scroll support surface  125  to cover or surround an outer circumference of the discharge space  122 . 
     An inner diameter of the storage space  124  may be larger (or greater) than an inner diameter of the second scroll support surface  125 . Of the second scroll support surface  125 , a first annular-shaped support surface  128   a  may be provided between the discharge space  122  and the oil storage space  124 , and the housing-side first sealing groove  125   a  may be provided on the first annular-shaped support surface  128   a . The first annular-shaped support surface  128   a  may be formed in an annular-shaped partition wall so as to separate the discharge space  122  and the oil storage space  124  from each other. 
     In addition, an outer diameter of the oil storage  124  may be smaller than an outer diameter of the second scroll support surface  125 . Accordingly, of the scroll support surface  125 , a second annular-shaped support surface  128   b  may be formed outside of the oil storage space  124 . The housing-side second sealing groove  125   b  may be provided on the second annular-shaped support surface  128   b.    
     As such, as the oil storage space  124  is separately provided but is opened toward the opened end of the rear housing, the rear housing  120  may be easily manufactured while expanding a volume of the storage space  124 . 
     In the oil storage space  124  according to this embodiment, rigidity of the rear housing  120  may be enhanced by a plurality of connecting ribs  128   c  (or oil storage space partitioning protrusion). Accordingly, the oil storage space  124  may be divided into a plurality of oil storage chambers  124   a , allowing rigidity of the rear housing  120  to be enhanced while forming the oil storage space  124 . 
     For example, the connecting rib  128   c  may radially connect between the first annular-shaped support surface  128   a  and the second annular-shaped support surface  128   b . Accordingly, the oil storage space  124  may be divided into the plurality of oil storage chambers  124   a  having an arc shape. As a result, as described above, the rear housing  120  may be physically reinforced while distributing a pressure of the storage space  124 . Further, as shown in  FIG. 9 , the connecting rib  128   c  may be formed such that the coupling hole  120   b  is radially located at a portion where the coupling bolt B is fastened, namely, a width range of the connecting rib  128   c . This may prevent the rear housing  120  from being deformed by a coupling force applied when the rear housing  120  is coupled to the main housing  110 . 
     In some cases, however, the second annular-shaped support surface  128   b  may be excluded. An outer end of the connecting rib  128   c  may be connected to the inner circumferential surface of the rear housing  120  defining the compression unit accommodation space  121 , allowing the oil storage space  124  to be further increased. 
     The oil storage space  124  according to this embodiment may be divided into the plurality of oil storage chambers  124   a  while communicating with each other. 
     Referring to  FIG. 10 , a height of the connecting rib  128   c  may be lower (or shorter) than a height of the second scroll support surface  125  so that the plurality of storage chambers  124   a  communicate with each other. Alternatively, the height of the connecting rib  128   c  may be equal to the height of the scroll support surface  125 . Here, an oil storage chamber connecting passage  128   d  (or space communication groove), such as a connection groove and a connection hole, may be formed at each of the connecting ribs  128   c  to allow neighboring oil storage chambers to communicate with each other. Also, a connection groove or a connection hole may be provided in each of the connecting ribs  128   c  even when the height of the connecting ribs  128   c  is lower than the height of the second scroll support surface  125 . 
     In addition, each of the connection ribs  128   c  may be provided with a pin groove  128   e , respectively, to which the anti-rotation pin  192  is fixed. Accordingly, the connecting rib  128   c  may form an angle and a position to correspond to the anti-rotation ring  191  inserted into the anti-rotation groove  154  of the orbiting scroll  150 . 
     However, the anti-rotation pin  191  may not necessarily be installed to the connecting rib  128   c . In other words, when the anti-rotation pin  191  is coupled to the connecting rib  128   c , the position of the connecting rib  128   c  may be constrained or limited to a position of the anti-rotation pin  191 . Accordingly, instead of installing the anti-rotation pin  192  to the connecting rib  128   c , a fixed protrusion (not shown) may be provided at the storage space  124  between the connecting ribs  128   c , so as to increase design freedom for the connecting rib  128   c.    
     As described above, the oil storage space  124  may communicate with the oil separation space  123  via the oil return passage  127 . Accordingly, an outlet end of the oil return passage  127  may be formed to communicate with any one of the plurality of oil storage chambers  124   a  constituting the oil storage space  124 . 
     The oil return passage  127  may be formed through a rear wall surface of the respective oil storage chamber. Alternatively, as illustrated in  FIG. 10 , an oil return protrusion (or return passage forming protrusion)  128   f  provided therein with the oil return passage  127  may be formed. This allows rigidity of the rear housing  120  to be enhanced. The oil return protrusion  128   f  may have a similar height to the height of the connecting rib  128   c.    
     Referring to  FIGS. 9 and 10 , a flow (or flow rate) controller  127   a  may be installed at the oil return passage  127 . The flow controller  127   a  may control a flow rate of oil passing through the oil return passage  127 , so that high-pressure oil, separated from the oil separation space  123 , is reduced to an intermediate pressure when the oil is introduced into the oil storage space  124 . Thus, the flow rate controller  127   a  may be made of a pressure reducing member, such as a pressure reducing pin and a pressure reducing rod, having an outer diameter smaller than an inner diameter of the oil return passage  127 . 
     Meanwhile, any one of the plurality of oil storage chambers  124   a  may communicate with the oil guide passage  159  of the orbiting scroll  150 . Accordingly, oil in the oil storage space  124  may flow into the rotating shaft coupling portion  153  via the oil guide passage  159 . The oil may flow into the respective bearing surfaces and compression chambers through the oil supply passage  165  of the rotating shaft  160 . 
     The oil storage space  124  according to this embodiment may have an annular shape.  FIG. 11  is a planar view of an oil storage space according to another embodiment. 
     The oil storage space  124  according to the embodiment of  FIG. 9  is divided into the plurality of oil storage chambers  124   a  having an arc shape, whereas the oil storage space  124  according to the embodiment of  FIG. 11  may have only one oil storage chamber  124   a . In this case, a volume of the storage space  124  may be further increased compared to the previous embodiment (the embodiment of  FIG. 9 ) as the connecting ribs are excluded (or eliminated). 
     In addition, even in the case of this embodiment in which the oil storage space  124  is formed in an annular shape without being divided into a plurality oil storage chambers, the anti-rotation pin  192  may also be installed by forming a pin fixing protrusion  120   d  provided at the oil storage space  124 , as described above. 
     Referring back to  FIGS. 6 and 7 , the orbiting scroll  150  may include the orbiting end plate  151 , the orbiting wrap  152 , and the rotating shaft coupling portion  153 . 
     The orbiting end plate  151  may be provided with a first guide passage  159   a  formed at an edge thereof, and a second guide passage  159   b  formed therein. The first guide passage  159   a  defining an inlet end of the oil guide passage  159  may be recessed from the second side surface  151   b  in an axial direction by a predetermined depth, and the second guide passage  159   b  communicating with the first guide passage  159   a  may be recessed to a predetermined depth in a radial direction. In addition, a third guide passage  159   c  penetrating from the second guide passage  159   b  to the first side surface  151   a  of the orbiting end plate  151  may be formed at the central portion of the orbiting end plate  151 . The third guide passage  159   c  may penetrate through a rear wall surface of the rotating shaft coupling portion  153  to communicate with the rotating shaft coupling portion  153 . 
     Further, the oil guide passage  159  may directly communicate with the suction chamber V 1  or an intermediate pressure chamber V 2 , as well as the rotating shaft coupling portion  153 .  FIG. 12  is a cross-sectional view of an oil guide passage according to another embodiment. 
     Referring to  FIG. 12 , a fourth guide passage  159   d  may be further provided at a middle portion of the oil guide passage  159 , for example, penetrating from the second guide passage  159   b  to an end portion of the orbiting wrap  152 . The fourth guide passage  159   d  may communicate with the end portion of the orbiting wrap  152  at a point or location where the fourth guide passage  159   d  forms a suction pressure or an intermediate pressure. From this location, an oil supply communication groove  159   e  may be further provided at the end portion of the orbiting wrap  152 . The oil supply communication groove  159   e  may be formed though a side wall surface of the orbiting wrap  152  so that oil flowing to the fourth guide passage  159   d  is quickly introduced into the compression chamber V 1  or the intermediate chamber V 2 . 
     Meanwhile, the thrust plate  180  described above may be installed between the orbiting scroll  150  and the rear housing  120 .  FIG. 13  is an enlarged cross-sectional view illustrating a portion of the motor-operated compressor according to an embodiment. 
     Referring to  FIG. 13 , the thrust plate  180  may be made of a material having higher wear resistance than the orbiting scroll  150  or the rear housing  120  since the thrust plate  180  is installed to reduce a friction loss and abrasion against the rear housing  120  while the orbiting scroll  150  performs an orbiting motion. 
     In addition, the thrust plate  180  may have an annular shape, and an outer circumferential surface thereof may be spaced apart from an inner circumferential surface of the compression unit accommodating space  121  of the rear housing  120  and an inner circumferential surface thereof may have the inner diameter equal to or larger than the inner diameter of the discharge space  122  so as to be located at the same position or outside of the discharge space  122 . The thrust plate  180  may be provided with a plurality of pin holes  180   a  to which the anti-rotation pin is coupled in a penetrating manner. The plurality of pin holes  180   a  may be formed along a circumferential direction with a predetermined distance therebetween. The pin hole  180   a  may be approximately equal to or slightly larger than the anti-rotation pin  192 . Accordingly, the front-side intermediate pressure space S 21  may communicate with the rear-side intermediate pressure space S 22  via the pin hole  180   a.    
     In addition, the thrust plate  180  may be further provided with the oil communication hole  180   b  that connects between the oil storage space  124  of the rear housing  120  and the oil guide passage  159  of the orbiting scroll  150 . The oil communication hole  180   b  may be provided at a position facing the oil guide passage  159  of the orbiting scroll  150 . However, the oil communication passage  180   b  may not necessarily be provided at the position facing the oil guide passage  159  if the front-side intermediate pressure space S 21  and the rear-side intermediate pressure space S 22  communicate with each other via the oil communication hole  159 . 
     However, it may be preferable that the oil communication hole  180   b  is disposed substantially at an opposite side of the oil return passage  127  based on the axial center Oc. For example, the outlet end of the oil return passage  127  may be provided at the lowest point of the oil storage space  124  as possible, so that oil separated in the oil separation space  123  is quickly introduced into the oil storage space  124 . Accordingly, the oil communication hole  180   b  may be provided at the highest point or near the highest point of the oil storage space  124 . This allows oil introduced into the oil storage space  124  to almost fill the entire oil storage space  124 . Then, the oil flows into the oil communication hole  180   b , so as to make all of the plurality of anti-rotation pins  192  contact with the oil in the oil storage space  124 , thereby effectively lubricating between the anti-rotation pin  192  and the anti-rotation ring  191 . 
     In the drawings, unexplained reference numerals  135  and V 3  denote a winding coil and a discharge chamber, respectively. 
     The motor-operated compressor according to the embodiments may operate as follows. 
     When power is applied to the drive motor  130 , the rotating shaft  165  may transfer a rotational force to the orbiting scroll  150  while rotating together with the rotor  132 . This allows the orbiting scroll  150  with a pin-and-ring structure to perform an orbiting motion. Accordingly, the compression chamber V is reduced in volume while continuously moving toward a central part or side. 
     Then, a refrigerant flows into the suction space S 1 , which is the motor chamber, through the inlet port  111 , and passes through a flow path provided between an outer circumferential surface of the stator  131  and the inner circumferential surface of the main housing  110 , an air gap between the stator  131  and the rotor  132 , or a gap between a stator core (not shown) and the winding coil  135 , and is then introduced into the compression chamber V via the suction port  145 . 
     Then, the refrigerant is compressed by the fixed scroll  140  and the orbiting scroll  150  while the orbiting scroll  150  orbits (or rotates) with respect to the fixed scroll  140 . The compressed refrigerant is discharged into the discharge space  122  provided at the rear housing  120  via the discharge port  157 . This refrigerant is then introduced into the oil separation space  123  from the discharge space  122  via the oil separation communication hole  122   a , so as to separate oil from the refrigerant. After separation, the refrigerant is discharged to a refrigeration cycle through the exhaust port  126 , whereas the oil in a mist state flows into the oil storage space  124  through the oil return passage  127 . As the oil return passage  127  is provided with the flow controller  127   a  made of a pressure reducing member, the oil in a high-pressure state is depressurized or reduced to an intermediate pressure, and is then introduced into the oil storage space  124 . 
     Then, an amount of the oil introduced into the oil storage space  124  is gradually increased to a predetermined oil level. The oil storage space  124  is divided into the plurality of oil storage chambers  124   a  by the connecting ribs  128   c , and the oil return passage  127  communicates with an oil storage chamber located at the lowest position of the oil storage chambers  124   a . However, as the height of the connecting rib  128   c  is lower than the height of the second scroll support surface  125 , or the oil storage chamber connecting passage  128   d  is provided at the connecting rib  128   c , the oil introduced into the storage chamber located at the lowest position flows into another oil storage chamber, thereby increasing the oil level. 
     Then, oil is filled in the rear-side intermediate pressure space S 22 , and this oil flows into the front-side intermediate pressure space S 21  through the oil communication hole  180   b  provided at the thrust plate  180 . The oil filled in the rear-side intermediate pressure space S 22  fills the front-side intermediate pressure space S 21  sealed between the scroll-side first sealing member  181  and the scroll-side second sealing member  182 . When oil is filled to a predetermined oil level of the front-side intermediate pressure space S 21 , the oil flows to the rotating shaft coupling portion  153  via the oil supply passage  159  provided at the orbiting scroll  150 . As oil is filled in the front-side intermediate pressure space S 21 , the oil is smeared on each of the anti-rotation pins  192  penetrating through the thrust plate  180  to be accommodated in the front-side intermediate pressure space S 21 , thereby lubricating between the anti-rotation pin  192  and the anti-rotation ring  191 . 
     Meanwhile, oil introduced into the rotating shaft coupling portion  153  is supplied to the bearing surface between the main bearing portion  162  of the rotating shaft  165  and the main bearing  171 , and the bearing surface between the eccentric portion  164  of the rotating shaft  165  and the eccentric bearing  173  via the oil supply groove  165   a  provided at the rear end of the rotating shaft  165  and the oil supply holes  165   b  and  165   c , thereby lubricating the respective bearing surfaces. The oil lubricating the respective bearing surfaces lubricates a lubricated surface between the fixed scroll  140  and the orbiting scroll  150  through a gap of the bearing surfaces, and is then introduced into the compression chamber V to be discharged together with a refrigerant. Such series of processes are repeated. 
     Here, as the fourth guide hole  159   d  formed through the orbiting wrap  152  at a middle portion of the guide passage  159  is provided at the orbiting scroll  150  toward the suction chamber V 1 , some or part of oil flowing into the rotating shaft coupling portion  153  flows into the suction chamber V 1  through the oil guide passage  159 , thereby evenly lubricating between the fixed scroll  140  and the orbiting scroll  150 . 
     Although not illustrated in the drawings, instead of separately providing the oil separation space described above, an inlet end of the oil return passage may communicate with the discharge space. Here, an oil separation portion (e.g., a collision-type oil separation portion or separator) may be separately provided in the discharge space, so that oil separated from the oil separation portion may be returned to the oil storage space via the oil return passage. 
     In a motor-operated compressor according to embodiments, a horizontal and frame scroll type motor-operated compressor is employed to exclude or remove a frame. This allows the number of components and manufacturing costs to be reduced, thereby achieving the smaller and lighter weight motor-operated compressor. 
     In addition, a sufficient oil storage space for oil separated from a refrigerant in a compression chamber can be ensured by providing the oil storage space at the adjacent to a discharge space of a rear housing. This allows stored oil to be quickly supplied to an area requiring lubrication. Accordingly, friction loss or abrasion caused by an insufficient amount of oil can be reduced, thereby improving compressor efficiency. 
     Further, the rear housing may be easily fabricated by providing the oil storage space at one side surface of the rear housing in an opened manner. Accordingly, manufacturing costs of the rear housing can be reduced and a sufficient oil storage space can be secured.