KR101533251B1 - Scroll compressor - Google Patents

Abstract

The horizontal scroll compressor according to the present invention is provided with an oil separator inside the casing, a recovery pump for recovering the oil separated from the oil separator and pumping the oil into the casing, and a lubricant pump for lubricating the recovered oil, Not only the oil is smoothly separated from the refrigerant discharged from the chamber but also the separated oil does not flow out to the discharge port together with the refrigerant and remains in the casing so that the sliding part of the compressor causes friction loss or wear due to oil shortage Which can improve the performance of the compressor.

Description

[0001] SCROLL COMPRESSOR [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal scroll compressor, and more particularly to a horizontal scroll compressor applicable to a vehicle.

Generally, a compressor is a device for compressing a fluid such as a refrigerant gas, and can be classified into a rotary compressor, a reciprocating compressor, and a scroll compressor depending on a method of compressing a fluid.

The scroll compressor has a structure in which a plurality of compression chambers are formed between both scrolls while two scrolls rotate relative to each other and the refrigerant is sucked and compressed continuously as the volume decreases as the compression chamber continuously moves toward the center, to be.

1 is a cross-sectional view showing the structure of a conventional horizontal scroll compressor.

As shown in the figure, the conventional scroll compressor has a main frame 2 and a sub frame 3 arranged in the inner space of the casing 1 at a predetermined interval in the lateral direction, A drive motor 4 for generating a rotational force is provided between the frame 3 and the center of the rotor 42 of the drive motor 4 is coupled to the orbiting scroll 6 through the main frame 2, And a crankshaft 5 for transmitting the rotational force of the motor 4 is coupled.

The fixed scroll 6 is fixedly provided on the front side of the main frame 2 and the fixed scroll 6 is provided with a pair of compression chambers S for engaging with the fixed scroll 5 and forming two pairs of compression chambers S, An Oldham's ring 8 is provided between the orbiting scroll 7 and the main frame 2 for rotating the orbiting scroll 7 while preventing the orbiting scroll 7 from rotating.

A main bearing 22 for supporting the crank shaft 5 in the radial direction is formed at the center of the main frame 2. A main bearing 22 for supporting the crank shaft 5 in the radial direction is formed in the bearing hole 21, Is installed.

The internal space of the casing 1 is divided into a suction space 15 in which the suction port 11 is formed by the main frame 2 and a discharge space 16 in which the discharge port 12 is formed, A discharge cover 64 for sealing the discharge port 63 of the fixed scroll 6 and forming the intermediate space 17 to communicate with the discharge space 16 is provided in the discharge space 16, Respectively.

An inverter housing 13 in which an inverter 81 for controlling the drive motor 4 is accommodated is provided on the front side of the casing 1 in a manner electrically connected to the drive motor 4. [ An air passage (13a) for cooling the inverter (81) by sucking outside air is formed in the inverter housing (13). A plurality of heat dissipating fins 13b for cooling the inverter housing 13 are formed on the front surface of the inverter housing 13.

Reference numeral 31 denotes a sub bearing for supporting the crankshaft in the radial direction. Reference numeral 32 denotes an oil pump. Reference numeral 41 denotes a stator of the drive motor. Reference numeral 51 denotes an oil passage. Reference numeral 61 denotes a fixed end plate. 72 is a swing lap, 73 is a boss portion, 74 is a pin bearing, and 82 is an agitator (IGBT).

The conventional horizontal scroll compressor as described above operates as follows.

That is, when power is applied to the drive motor 4, the crankshaft 5 rotates together with the rotor 4b of the drive motor 4, and the orbiting scroll 7 is driven by the articulation 8, The pair of compression chambers S are continuously formed between the fixed lap 62 and the orbiting lap 72 together with the pivoting motion of the eccentric distance from the upper surface of the fixed lap 62 and the orbiting lap 72,

The refrigerant gas is sucked into the suction space 15 of the casing 1 through the suction port 11 as the compression chamber S is moved to the center by the continuous pivotal movement of the orbiting scroll 7 and the volume is reduced, The refrigerant gas is sucked into the compression chamber through the suction port provided in the fixed scroll 7 and is compressed and discharged to the discharge space 16 of the casing 1 through the discharge port 63.

At this time, the refrigerant discharged through the discharge port 63 is mixed with the oil to move to the discharge space 16. The refrigerant and the oil are separated from the discharge space 16, and the refrigerant flows through the discharge port 12 into the refrigerating cycle While the oil was collected in the discharge space 16 and supplied to the sliding portion through the oil pump 32. [

However, in the above-described conventional horizontal scroll compressor, the oil is not smoothly separated from the refrigerant discharged from the compression chamber P, but is discharged to the outside of the compressor to increase the oil flow rate. As a result, There is a problem that frictional loss or abrasion occurs in the sliding portion. Particularly, even when the oil separator is installed in the compressor casing 1, the oil separated by the oil separator flows out to the discharge pipe 12 together with the refrigerant due to the pressure difference, and oil shortage can be caused.

SUMMARY OF THE INVENTION An object of the present invention is to prevent the oil from being smoothly separated from the refrigerant discharged from the compression chamber and to allow the separated oil to remain in the compressor casing without flowing out to the discharge port, The present invention is directed to a horizontal scroll compressor which can be used as a scroll compressor.

In order to achieve the object of the present invention, A driving motor installed in an inner space of the casing to generate a rotational force; A crankshaft coupled to a rotor of the drive motor; A compression unit having an orbiting scroll coupled to the crankshaft and pivotally moving and a fixed scroll engaging with the orbiting scroll to form a compression chamber; An oil separator installed in an inner space of the casing to separate refrigerant and oil; A first pump for pumping the oil separated in the oil separator to the internal space of the casing; And a second pump for pumping the oil carried in the inner space of the casing toward the compression portion.

The horizontal scroll compressor according to the present invention is provided with an oil separator inside the casing, a recovery pump for recovering the oil separated from the oil separator and pumping the oil into the casing, and a lubricant pump for lubricating the recovered oil, Not only the oil is smoothly separated from the refrigerant discharged from the chamber but also the separated oil does not flow out to the discharge port together with the refrigerant and remains in the casing so that the sliding part of the compressor causes friction loss or wear due to oil shortage Which can improve the performance of the compressor.

1 is a longitudinal sectional view showing an example of a conventional horizontal scroll compressor,
FIG. 2 is a perspective view showing an appearance of a lateral scroll compressor of the present invention,
FIG. 3 is a perspective view of a transverse scroll compressor according to FIG. 2,
Fig. 4 is a longitudinal sectional view showing the interior of the transverse scroll compressor according to Fig. 2,
Fig. 5 is a plan view showing the wrap thickness shape of the orbiting wrap in the transverse scroll compressor according to Fig. 2,
Fig. 6 is a front view of the oil separator in a rear view of the oil separator in the transverse scroll compressor according to Fig. 4, Fig.
7 is a sectional view taken along the line "II" in Fig. 6,
FIG. 8 is a schematic view showing a process in which oil is separated by the oil separator in the transverse scroll compressor according to FIG. 6 and recovered into the internal space of the casing;
FIG. 9 is a schematic view showing a process of pumping oil contained in an inner space of a casing into a crankshaft in the transverse scroll compressor according to FIG. 6;

Hereinafter, a lateral scroll compressor according to the present invention will be described in detail with reference to an embodiment shown in the accompanying drawings.

FIG. 2 is a perspective view showing the outer appearance of the lateral scroll compressor of the present invention, FIG. 3 is a perspective view of the transverse scroll compressor according to FIG. 2, .

As shown in the drawing, the horizontal scroll compressor according to the present invention includes a casing 101, a driving motor 102 for generating a rotating force at one side of an inner space of the casing 101, 101 is provided with a compression section including a fixed scroll 104 and an orbiting scroll 105 and receiving a rotational force of the drive motor 102 to form a pair of two compression chambers P, A control unit 106 for controlling the operation of the compressor is installed at one side of the unit.

The drive motor 102 can be wound on the stator 121 in a concentrated winding manner. A constant speed motor having the same rotational speed of the rotor 122 may be used as the drive motor 102. However, in consideration of multi-functioning of the refrigeration apparatus to which the compressor is applied, A motor can be used. A crankshaft 125 which is rotatably coupled to the orbiting scroll 105 to be described later and transmits the rotational force of the drive motor 102 to the orbiting scroll 105 is coupled to the rotor 122 of the drive motor 102 .

The fixed scroll (104) may be fixedly coupled to one side of the main frame (102). A fixed scroll plate 141 is formed in a disk shape so as to be fixed to the main frame 102. A fixed scroll 142 for forming a compression chamber P is formed on one side of the fixed scroll plate 141 A suction port 143 directly connected to the suction port 1125 is formed at the edge of the fixed plate 141 and a discharge port 144 may be formed at the center of the fixed plate 141. A discharge cover 145 for guiding the refrigerant discharged through the discharge port 144 to move to the first space S1 without passing through the second space S2 is provided on the back surface of the fixed scroll 104 . The discharge cover 145 may be fastened to the fixed scroll 104 and the fixed scroll 104 may be fastened to the main frame 102. The discharge cover 145 may be fixed to the main frame 102 together with the fixed scroll 104, And the discharge cover 145, the fixed scroll 104, and the main frame 102 can be fastened to the shell 111 together. When the discharge cover 145 and the fixed scroll 104 or the discharge cover 145 and the fixed scroll 104 and the main frame 102 are fastened together, the number of fastening bolts and the number of assembly bolts are reduced, Can be saved.

An orbiting scroll 105 may be installed between the upper surface of the main frame 102 and the bottom surface of the fixed scroll 104 to form a pair of compression chambers P together with the fixed scroll 104. The orbiting scroll (105) is formed in a disc shape so as to perform a swing motion between the main frame (102) and the fixed scroll (104), and a fixed lap (142) And a boss unit 153 coupled to the crankshaft 125 may be formed on the other side of the swivel rigger 151. [

An orbiting ring 171 is provided between the orbiting scroll 105 and the main frame 102 to allow the orbiting scroll 105 to rotate only without revolving by receiving the rotational force of the driving motor 102, Can be installed. Although not shown in the drawing, the anti-rotation member may be made of a keyless bearing in addition to a bearing having a key, a pin having a ring on the orbiting scroll and a ring having a ring on the opposite side, .

The fixed lap 142 and the orbiting wrap 152 may be formed in an involute shape having a uniform wrap thickness or a constant number in which the wrap thickness becomes thicker at a constant rate in the starting end direction at the end of the wrap, Or may be formed in a spiral shape.

In the case where the fixed wraps 142 and the orbiting wraps 152 are formed in the usual involute shape, the thickness of the wraps becomes constant, and the volume change rate becomes constant. Therefore, in order to obtain a high compression ratio in a scroll compressor using an involute curve, it is necessary to increase the number of windings of the wrap or increase the height of the wrap. However, if the number of turns of the lap increases, the size of the compressor also increases. If the height of the lap is increased, the lap strength may be weakened and the reliability may be deteriorated.

On the other hand, when the fixed wraps 142 and the revolving wraps 152 are formed in the form of a logarithmic spiral, the compression ratio can be increased to a certain level without increasing the number of turns of the wraps. However, (I.e., the end of the wrap) is determined, the width of the wrap at the discharge end (i.e., the start end of the wrap) is also determined to lower the design freedom of the wrap. Thus, the compression ratio of the scroll compressor is adjusted There was a limit to the design.

Meanwhile, the stationary wrap 142 and the orbiting wrap 152 may be formed to have a variable section between a plurality of uniform intervals. That is, the thickness of the discharge end of the lap (i.e., the thickness of the starting end of the lap) is significantly larger than the suction end thickness (i.e., the thickness of the end of the lap) so that the thickness of the lap increases according to the change of the compression ratio. Can be improved.

As shown in FIG. 5, the fixed lap and the orbiting lap (the swing lap and the orbiting lap are formed to be symmetrical to each other, A first uniform section 1521 having the same wrap thickness is formed up to a predetermined interval and a variable section 1522 is formed in which the thickness of the wrap increases toward the discharge side from the inner end of the first uniform section 1521 to a predetermined section, The second uniform section 1523 having the same wrap thickness can be formed from the inner end of the variable section 1522 to the discharge end of the wrap (start angle of the wrap).

The wrap thickness of the first uniform section 1521 may be made thinner than the wrap thickness of the second uniform section 1522. [ Preferably, the wrap thickness ratio t2 / t1 in the two uniform sections, when the wrap thickness of the first uniform section 1521 is t1 and the wrap thickness of the second uniform section 1523 is t2, Can be formed to be at least 1.5? (T2 / t1)? 3.0. Here, when the ratio of the wrap thicknesses in the two uniform sections 1521 and 1523 is 1.5 or less, since the wrap thickness on the discharge-side end side is thin compared to the conventional wrapping wrap of the logarithmic spiral shape, . On the other hand, when the wrap thickness ratio is 3.0 or more, the wrap thickness of the second uniform section 1523 on the discharge port side becomes too thick, making it difficult to secure a proper discharge port, There is a fear that the performance may deteriorate.

The wrap thickness t3 of the variable section is equal to or greater than the wrap thickness t1 of the first uniform section 1521 and the wrap thickness t2 of the second uniform section 1523 is the same Or smaller.

2 to 4, the casing 101 includes a shell (not shown) having a first space S1 formed at both ends thereof to be a discharge space and having a drive motor 102 installed therein A front cap 112 which is connected to one end of the shell 111 to form a second space S2 forming a suction space and accommodates the compressed portion; A top plate 113 which forms a third space part S3 forming a suction space together with the second space part S2 and accommodates the control unit 106, And a rear housing 114 which forms a fourth space S4 forming a discharge space or an oil separation space together with the first space S1.

The main frame 103 separating the first space S1 and the second space S2 can be closely attached to the front end of the shell 111 while supporting the crankshaft 125. [ And the space between the shell 111 and the main frame 103, between the main frame 103 and the front cap 112, between the front cap 112 and the top plate 113 and between the shell 111 and the rear housing (Not shown) such as a gasket or an O-ring may be interposed between the first and second seal members 114 and 114, respectively.

A bearing hole 131 is formed in the center of the main frame 103 to support the crank shaft 125 in the radial direction and a bearing hole 131 is formed at one side of the main bearing 103 for supporting the crank shaft 125 in the radial direction 132 may be installed.

A suction port 1125 is formed in the front cap 112 to communicate with the second space S2 and a fourth space S4 is formed in the rear housing 114 And the exhaust passage 147 and the communication passage 133 are formed in the fixed scroll 104 and the main frame 103 so that the intermediate space S5 and the first space S1 are communicated with each other. Can be formed.

A terminal portion 116 for electrically connecting the terminal of the drive motor 102 and the terminal of the control unit 106 may be formed on one side of the shell 111. [ The terminal portion 116 is formed of a plurality of terminal pins 1161 and the molding portion 1162 is formed around the plurality of terminal pins 1161 by using an insulating material such as plastic to form the first space portion S1 and the second It may be preferable that the space S2 is not communicated through the terminal portion 116. [

The front cap 112 has a cap part 1121 formed in an annular shape and coupled to the main frame 103 and a cap part 1121. The cap part 1121 is horizontally laid on one side of the cap part 1121 to cover the second space part S2 and the third space part S3 And a plate portion 1122 for separating the plate portion 1122 from the plate portion 1122. An insulated gate bipolar transistor (IGBT) 161, which is a part of the control unit 106, is coupled to the plate portion 1122, and a substrate 162 electrically connected to the eye portion 161 is connected to a predetermined height As shown in FIG.

The cap portion 1121 may be formed with a suction port 1125 to which a suction pipe is connected. The inlet port 1125 may be divided by the plate portion 1122 so that the inlet port 1125 thereof may be formed so as to simultaneously communicate with the second space portion S2 and the third space portion S3, 1125 may be formed to communicate independently with the second space S2 or the third space S3 by the plate portion 1122. [

The plate portion 1122 may be formed with a communication hole 1126 to allow the second space S2 and the third space S3 to communicate with each other. Thus, even when the refrigerant is sucked into the second space portion S2, sucked into the third space portion S3, or sucked into the second space portion S2 and the third space portion S3 at the same time, 2 can be sucked into the suction port 143 of the fixed scroll 104 through both the space S2 and the third space S3.

6 and 7, a discharge port 1141 is formed at one side edge of the rear housing 114 so as to be connected to the discharge pipe, and an inlet hole 117a and an outlet end 117b are formed in the discharge port 1141 Shaped oil separator 117 having a tubular shape can be inserted and installed. The oil separator 117 is preferably installed in a direction perpendicular to the installation surface so that the separated oil can be smoothly guided to the recovery pump 107 to be described later without being discharged together with the refrigerant through the oil separator 117 . However, in order to increase the centrifugal force to double the oil separation effect, the oil separator 117 may be inclined.

An oil separation groove 1142 may be formed in the rear housing 114 so that the oil separator 117 can be inserted into the front side (hereinafter referred to as the front side of the drive motor). The inner diameter of the oil separation groove 1142 may be formed to be larger than the outer diameter of the oil separator 117 so that the oil separator 117 can be spaced apart by a predetermined distance. An introduction hole 1143 is formed in the upper half of the oil separation groove 1142 so that the refrigerant of the first space S1 can be introduced into the oil separation groove 1142. In the lower half of the oil separation groove 1142, An inlet of the oil recovery hole 1144 for guiding the oil separated in the oil separator 117 to the recovery pump 107 to be described later may be formed. The oil recovery hole 1144 is formed to be inclined in the left-right direction, and can be smoothly guided by the oil viscosity. The rear housing 114 may be provided with an oil supply hole 1145 for guiding the oil carried in the fourth space S4 of the casing 101 to the oil supply pump 108 to be described later. The oil refilling hole 1145 may be formed so as to be inclined in the forward and backward directions smoothly guided by the oil viscosity.

A fuel supply pump 108 for supplying oil through the oil passage 1251 of the crankshaft 125 may be installed at the center of the front surface of the rear housing 114. The oil feed pump 108 may be composed of a trochoidal gear pump having an inner gear and an outer gear. The inner gear of the oil feed pump 108 is integrally coupled to the crankshaft 125 and the outer gear of the oil feed pump 108 is engaged with the inner gear and inserted into the rear housing 14 to be engaged. The suction side of the oil feed pump 108 communicates with the outlet end of the oil refueling hole 1145 while the discharge side of the oil refueling pump 108 can communicate with the oil flow path 1251 of the crankshaft 125. [

A bearing housing 115 supporting the rear end of the crankshaft 125 may be installed on the front side of the rear housing 114. The bearing housing 115 includes a discharge passage 1151 for guiding the refrigerant and the oil to move to the fourth space portion S4 and an oil passage 1151 for guiding the oil in the first space portion S1 to the fourth space portion S4. And a bearing 118 for supporting the rear end of the crankshaft 125 can be inserted and coupled to the center of the front side. A recovery pump 107 for pumping oil separated from the oil separator 117 and guiding the oil to the internal space of the casing 101 may be installed at the center of the rear side of the bearing housing 115. The recovery pump 107 may be composed of a trochoidal gear pump having an inner gear and an outer gear. The inner gear of the recovery pump 107 is integrally coupled to the crankshaft 125 and the outer gear of the recovery pump 107 is engaged with the inner gear and inserted into the rear housing 114 to be engaged. The suction side of the recovery pump 107 communicates with the outlet end of the oil recovery hole 1144 while the discharge side of the recovery pump 107 can communicate with the inner space of the casing 101. [ Accordingly, the oil separated by the oil separator 117 flows into the oil recovery hole 1144 by the pumping force of the recovery pump 107 before being discharged to the discharge port 1141 together with the refrigerant according to the pressure difference, .

The oil separator 117 is formed with a fixed portion 1171 to be inserted into an outlet 1141 provided in the rear housing 114 and a fixed portion 1171 is inserted into the oil separation groove 1142 in the fixed portion 1171, And the oil separating portion 1172 can be formed integrally. An inlet hole 117a of the oil separator 117 communicating with the oil separating groove 1142 is formed in the outer peripheral surface of the lower half of the oil separating portion 1172 and an outlet hole 117a communicating with the outlet 1141 is formed in the upper end of the oil separating portion 1172 The outlet end 117b of the oil separator 117 can be formed.

Here, in order to increase the area in which the refrigerant contacts the oil separator, it is preferable to form the contact surface portion 1173 on the outer peripheral surface of the oil separator 1172 as shown in FIG. The contact surface portion 1173 may be formed in various shapes such as a straight shape or a curved shape. However, it is preferable that the contact surface portion 1173 is formed in a spiral shape so that the refrigerant can flow along the oil separating portion 1172.

In the drawing, reference numerals 107a denote discharge ports of the recovery pump, and reference numeral 146 denotes a check valve.

The horizontal scroll compressor according to the present embodiment as described above can be operated as follows.

That is, when the power is applied to the driving motor 102, the crankshaft 125 rotates together with the rotor 142 to transmit the rotational force to the orbiting scroll 105.

The orbiting scroll 105 is then rotated by an eccentric distance from the main frame 102 by means of the arching 171 to move two pairs of compressions continuously moving between the stationary wrap 142 and the orbiting wrap 152 Thereby forming a seal P.

Then, the compression chamber P is moved to the center by the continuous turning movement of the orbiting scroll 105 to decrease the volume thereof, thereby compressing the refrigerant sucked into the compression chamber P through the suction port 1125, And is discharged to the first space portion S1 of the casing 101 through the discharge port 144 communicated with the final compression chamber on the inner side.

4, the refrigerant discharged from the compression chamber P is discharged to the intermediate space S5 by the discharge cover 145, and the refrigerant discharged to the intermediate space S5 And moves to the first space portion S1 through the exhaust passage 147 of the fixed scroll 104 and the communication passage 133 of the main frame 102. [ The refrigerant moving to the first space S1 moves to the fourth space S4 through the discharge passage 1151 of the bearing housing 115 and the refrigerant moves to the fourth space S4. The oil is centrifuged while being rolled along the outer peripheral surface of the oil separator 117.

At this time, the refrigerant separated from the oil moves through the inside of the oil separator 117 to the refrigeration cycle through the discharge port 1141 as shown in FIG. 8, while the separated oil is pumped by the recovery pump 107, And is discharged to the inner space of the casing 101, that is, the first space S1, which is the front side of the bearing housing 115, via the bearing 1144. 9, the oil is supplied to the fourth space portion S4 through the oil passage 1152 of the bearing housing 115 by a pressure difference between the first and fourth space portions S1 and S4 And is pumped to the oil supply hole 1145 by the oil supply pump 119 and supplied to the compression unit.

In this way, it is possible to prevent the refrigerant discharged from the compression chamber and the oil from being separated by the oil separator in the fourth space portion, and to prevent the oil from flowing out to the outside of the compressor together with the refrigerant, The oil separated from the refrigerant is prevented from flowing out to the discharge port together with the refrigerant due to the pressure difference inside the casing so that a large amount of oil flows out of the compressor Can be effectively prevented. As a result, the sliding portion of the compressor can prevent the friction loss or wear due to the oil shortage, thereby improving the compressor performance and reliability.

101: casing 111: shell
112: front cap 1125: inlet
113: Top plate 114: Rear housing
1141: Outlet port 1142: Oil separation groove
1143: introduction hole 1144: oil recovery hole
1145: Oil supply hole 115: Bearing housing
1151: discharge passage 1152: oil passage
117: oil separator 117a: inlet opening
117b: outlet end 102: drive motor
125: crankshaft 103: main frame
132: main bearing 104: fixed scroll
132: fixed lap 143: suction port
144: Discharge port 105: orbiting scroll
151: turning display 152: turning wrap
106: control unit 171:
107: recovery pump 108: refueling pump
P: compression chambers S1, S2, S3, S4:
S5: Intermediate space

Claims (9)

A casing including a discharge port and a rear housing having an exhaust hole for guiding the refrigerant to the discharge port;
A driving motor installed in an inner space of the casing to generate a rotational force;
A crankshaft coupled to a rotor of the drive motor;
A compression unit having an orbiting scroll coupled to the crankshaft and pivotally moving and a fixed scroll engaging with the orbiting scroll to form a compression chamber;
An oil separator installed in an inner space of the casing to separate refrigerant and oil;
A first pump for pumping the oil separated in the oil separator to the internal space of the casing; And
And a second pump for pumping oil carried in the inner space of the casing toward the compression section,
And the oil separator is installed in the rear housing so as to be positioned between the exhaust hole and the exhaust port. delete The method according to claim 1,
Wherein the oil separator is formed in a tubular shape having an inlet end and an outlet end so that an outlet end of the oil separator is in direct communication with the outlet,
Wherein an inlet end of the oil separator is formed at a lower position than the exhaust hole. The method of claim 3,
And an oil return flow path for guiding the oil separated from the oil separator to the first pump is formed in the rear housing. 5. The method of claim 4,
Wherein an inlet of the oil recovery passage is formed at a position lower than an inlet end of the oil separator. delete delete 5. The method of claim 4,
Wherein the rear housing is provided with an oil supply passage for guiding the oil carried by the inner space of the casing to the second pump.

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