Turbo compressor

Abstract

A turbo compressor is disclosed. The turbo compressor may include a housing, a rotary shaft, a bearing, a cooling flow path, and a buffer. A portion of refrigerant condensed by a condenser may be introduced through the inlet of the housing. The cooling flow path may be provided inside the housing, and may supply the refrigerant introduced through the inlet to a bearing. The buffer may communicate with the inlet, and may induce a phase change of the refrigerant introduced through the inlet. Accordingly, the buffer may prevent the inflow of liquid refrigerant from flowing thereinto.

Description

turbo compressor

[0001] The present invention relates to a turbo compressor capable of preventing damage to the bearing.

[0002] A turbo compressor compresses the working gas by converting a portion of the kinetic energy into pressure energy through centrifugal force applied by rotating the impeller at high speed.

[0003] Meanwhile, thrust bearings support axial loads by forming a pressure field through relative rotational motion between the thrust runner and the thrust bearing as the rotating shaft of rotating machinery, such as turbo compressors, rotates.

[0004] In order to form the above pressure field, the flow rate of the working fluid, such as a refrigerant, must be supplied sufficiently smoothly.

[0005] In addition, while the thrust bearing is operating, the gap between the thrust runner of the rotating shaft and the thrust bearing may be formed narrowly, for example, to 3 to 6 μm. Heat is generated by fluid friction in the gap, so sufficient cooling is required.

[0006] Prior art patent document KR 10-2023-0014711 (published January 30, 2023; hereinafter referred to as 'Patent Document 1') discloses a compressor drive shaft assembly and a compressor including the same.

[0007] According to Patent Document 1, a cooling channel is provided to directly supply a refrigerant to the thrust bearing and the journal bearing, respectively. The cooling channel is designed to take into account the pressure loss and resistance of the fluid and can handle the heat generated by the bearing.

[0008] However, in the case of Patent Document 1, if the refrigerant is supplied directly to the bearing through the cooling channel, the refrigerant may undergo a rapid phase change in the bearing section, for example, from a liquid phase to a gas phase.

[0009] As a result, there is a problem in which damage occurs to the bearing due to the rapid phase change of the refrigerant.

[0010] In addition, there is a problem where the refrigerant cannot flow smoothly if the viscosity of the refrigerant increases or if a pressure difference occurs due to a phase change, causing the refrigerant flow path to become blocked.

[0011] The objective of the present invention is to provide a turbo compressor with a structure capable of solving the aforementioned problems.

[0012] The first objective is to provide a turbo compressor with a structure that prevents liquid refrigerant from entering the bearing.

[0013] The second objective is to provide a turbo compressor with a structure capable of minimizing flow resistance in the cooling channel.

[0014] The third objective is to provide a turbo compressor with a structure capable of minimizing heat generation in the bearings.

[0015] The fourth objective is to provide a turbo compressor with a structure capable of cooling the electric motor.

[0016] As a result of intensive research, the inventors have found that the problem of the present invention or the first to fourth objectives described above can be achieved by the following embodiments of the present invention.

[0017] To achieve the above-mentioned purpose, a turbo compressor according to one embodiment of the present invention comprises: a housing having an inlet and an outlet formed therein; a rotating shaft rotatably provided inside the housing; an impeller coupled to one end of the rotating shaft; a drive unit having a rotor coupled to the rotating shaft and a stator surrounding the rotor; a bearing rotatably supporting the rotating shaft; a cooling passage provided inside the housing and supplying a refrigerant introduced through the inlet to the bearing; and a buffer communicating with the inlet and having a cross-sectional area larger than that of the inlet and the cooling passage.

[0018] Through this, the buffer can prevent the inflow of liquid refrigerant.

[0019] According to one example, the buffer can expand the volume of the liquid refrigerant introduced through the inlet and change it into a gaseous refrigerant.

[0020] According to one example, it further includes a thrust runner formed to protrude radially from one side of the rotational shaft. The bearing may include a thrust bearing spaced apart from one surface of the thrust runner with a gap and supporting an axial load of the rotational shaft; and a journal bearing spaced apart from the outer surface of the rotational shaft with a gap and supporting a radial load of the rotational shaft.

[0021] According to one example, the buffer comprises a first buffer provided upstream of the cooling channel with respect to the flow direction of the refrigerant and delivering the refrigerant introduced through the inlet to the cooling channel.

[0022] The above cooling passage includes: a thrust cooling passage that communicates with the first buffer and the thrust bearing and supplies a portion of the refrigerant vaporized in the first buffer to the thrust bearing; and a journal cooling passage that communicates with the first buffer and the journal bearing and supplies another portion of the refrigerant vaporized in the first buffer to the journal bearing.

[0023] Through this, the above cooling channel can supply refrigerant to the bearing to cool the bearing.

[0024] According to one example, the buffer further includes a second buffer provided downstream of the thrust cooling channel with respect to the flow direction of the refrigerant and transferring the refrigerant that has passed through the thrust cooling channel to the thrust bearing.

[0025] Through this, the second buffer can prevent liquid refrigerant from flowing into the thrust bearing by secondarily expanding the volume of the refrigerant that has passed through the thrust cooling path.

[0026] According to one example, the buffer further includes a third buffer provided downstream of the journal cooling channel with respect to the flow direction of the refrigerant and transferring the refrigerant that has passed through the journal cooling channel to the journal bearing.

[0027] Through this, the third buffer can prevent liquid refrigerant from flowing into the journal bearing by secondarily expanding the volume of the refrigerant that has passed through the journal cooling path.

[0028] According to one example, the thrust bearing comprises: a first thrust bearing spaced apart from one surface of the thrust runner with a gap; and a second thrust bearing spaced apart from the other surface of the thrust runner with a gap, facing in a direction opposite to the one surface of the thrust runner with respect to the axial direction.

[0029] Through this, the first thrust bearing and the second thrust bearing can support the axial load of the rotation axis in both directions.

[0030] According to one example, a bearing housing is provided inside the housing. The bearing housing includes a first bearing housing and a second bearing housing. The first bearing housing has a thrust cooling passage inside. The first bearing housing has a first receiving portion formed as a recess on one surface to accommodate the first thrust bearing and a portion of the thrust runner.

[0031] The second bearing housing has the journal cooling channel inside. The second bearing housing has a second receiving portion formed as a recess on one surface to accommodate the second thrust bearing and another part of the thrust runner.

[0032] Through this, the first bearing housing can supply refrigerant to the thrust bearing by providing a thrust cooling path. The second bearing housing can supply refrigerant to the journal bearing by providing a journal cooling path.

[0033] According to one example, the buffer extends in the circumferential direction of the rotation axis.

[0034] Through this, the buffer can circulate the refrigerant along the circumferential direction.

[0035] A turbo compressor according to another embodiment of the present invention comprises: a housing having an inlet and an outlet formed therein for introducing and receiving external refrigerant; a rotating shaft rotatably provided inside the housing; an impeller coupled to one end of the rotating shaft; a driving unit coupled to the rotating shaft and driving the impeller; a thrust runner formed to protrude radially from one side of the rotating shaft; a bearing rotatably supporting the rotating shaft; a bearing housing provided inside the housing and having a cooling passage that supplies refrigerant introduced through the inlet to the bearing and a receiving portion that accommodates the thrust runner; and a buffer communicating with the inlet and having a cross-sectional area larger than that of the inlet.

[0036] Through this, the buffer can prevent the inflow of liquid refrigerant.

[0037] According to another example, the bearing housing is formed in a cylindrical shape, and the rotation axis penetrates the center of the bearing housing. The buffer includes a first buffer. The first buffer is positioned between the inner surface of the housing and the outer surface of the bearing housing and is formed in a ring shape to surround the bearing housing.

[0038] Through this, the first buffer is provided between the housing and the bearing housing, thereby blocking the inflow of liquid refrigerant.

[0039] According to another example, the bearing comprises: a thrust bearing spaced apart from one surface of the thrust runner and supporting an axial load of the rotation axis; and a journal bearing spaced apart from the rotation axis and supporting a radial load of the rotation axis.

[0040] The bearing housing comprises: a first bearing housing having a thrust cooling passage that communicates with the first buffer and the thrust bearing and supplies a portion of the refrigerant passing through the first buffer to the thrust bearing, and a first receiving portion that accommodates a portion of the thrust runner; and a second bearing housing having a journal cooling passage that communicates with the first buffer and the journal bearing and supplies another portion of the refrigerant passing through the first buffer to the journal bearing, and a second receiving portion that accommodates another portion of the thrust runner.

[0041] Through this, a thrust cooling channel is provided inside the first bearing housing, allowing refrigerant to be supplied to the thrust bearing. A journal cooling channel is provided inside the second bearing housing, allowing refrigerant to be supplied to the journal bearing.

[0042] According to another example, the first and second bearing housings are each formed in a cylindrical shape and are arranged to be in contact with the axial direction of the rotation axis.

[0043] The thrust cooling channel and the journal cooling channel are each provided in multiple numbers. Each of the multiple thrust cooling channels is formed to penetrate the first bearing housing in the radial direction. Each of the multiple journal cooling channels is formed to penetrate the second bearing housing in the radial direction.

[0044] Through this, the first and second bearing housings can each distribute the refrigerant evenly to a plurality of thrust cooling channels and a plurality of journal cooling channels.

[0045] According to another example, the thrust bearing comprises: a first thrust bearing that is received in the first receiving portion and spaced apart from one side of the thrust runner by a gap; and a second thrust bearing that is received in the second receiving portion and spaced apart from the other side of the thrust runner by a gap.

[0046] Through this, the first and second thrust bearings can support the axial load of the rotating shaft in both directions without lubrication.

[0047] According to another example, the bearing housing comprises: a thrust communication channel extending from the receiving portion to communicate with the thrust bearing; and a plurality of thrust communication channel outlets formed penetrating the interior of the bearing housing to communicate with the thrust communication channel and the internal space of the housing.

[0048] Through this, the thrust connecting passage and the plurality of thrust connecting passage outlets can minimize flow resistance without the refrigerant becoming stagnant in one place. Additionally, the refrigerant can be injected into the internal space of the housing through the plurality of thrust connecting passage outlets to cool electric parts such as the stator.

[0049] According to another example, the bearing housing comprises: a radial extension formed radially to surround a portion of the thrust runner; and an axial extension extending axially from an inner end of the radial extension and formed in a cylindrical shape to surround the rotation axis.

[0050] Through this, the bearing housing can have a circumferential circulation path structure inside.

[0051] According to another example, the journal bearing may be positioned between the inner surface of the axial extension and the outer surface of the rotation axis.

[0052] Through this, the journal bearing can support the radial load of the rotating shaft without lubrication.

[0053] According to another example, the buffer comprises: a second buffer that is in communication with the thrust cooling channel and the thrust bearing, is positioned between the inner surface of the first bearing housing and the outer surface of the rotating shaft, extends along the circumferential direction from the outer surface of the rotating shaft, and is formed as a recess; and a third buffer that is in communication with the journal cooling channel and the journal bearing, is positioned between the inner surface of the second bearing housing and the outer surface of the rotating shaft, extends along the circumferential direction from the outer surface of the rotating shaft, and is formed as a recess.

[0054] Through this, the second buffer and the third buffer can each convert the liquid refrigerant that has passed through the thrust cooling channel and the journal cooling channel into a gaseous refrigerant.

[0055] According to another example, it further includes a plurality of housing communication outlets that are in communication with the third buffer and the internal space of the housing and are formed penetratingly into the inner side of the second bearing housing.

[0056] Through this, the plurality of housing communication outlets can minimize the flow resistance of the refrigerant without the refrigerant introduced into the interior of the bearing housing becoming stagnant in one place. In addition, a portion of the refrigerant supplied to the journal bearing can be supplied into the internal space of the housing to cool the electric part.

[0057] According to another example, the impeller comprises a first impeller coupled to one end of the rotating shaft; and a second impeller coupled to the other end of the rotating shaft.

[0058] The bearing comprises: a first journal bearing positioned toward the first impeller along the axial direction of the rotation axis with respect to the transmission member; a second journal bearing positioned toward the second impeller along the axial direction with respect to the transmission member; and a thrust bearing positioned between the first impeller and the first journal bearing.

[0059] Through this, the thrust bearing, the first journal bearing, and the second journal bearing are arranged in that order along the axial direction from the first impeller toward the second impeller, thereby shortening the axial length of the rotating shaft and the compressor.

[0060] According to an embodiment of the present invention, the following effects can be achieved.

[0061] First, a first buffer is provided between the housing and the bearing housing. An inlet is formed through the housing. Refrigerant condensed in the condenser can flow into the first buffer through the inlet. The first buffer has a cross-sectional area larger than that of the inlet. The first buffer extends circumferentially along the inner perimeter of the housing. Through this, the first buffer can prevent the liquid refrigerant from flowing into the bearing by expanding the volume of the liquid refrigerant flowing in through the inlet and vaporizing it into gaseous refrigerant.

[0062] Second, a cooling channel is formed inside the bearing housing. The cooling channel is connected to communicate with the first buffer. The cooling channel supplies refrigerant introduced from the first buffer to the bearing, thereby minimizing heat generation in the bearing.

[0063] A thrust cooling channel is formed to penetrate the interior of the first bearing housing. A journal cooling channel is formed to penetrate the interior of the second bearing housing.

[0064] Third, the second buffer is provided between the inner surface of the first bearing housing and the outer surface of the rotating shaft. The second buffer can cause the liquid refrigerant passing through the thrust cooling path to undergo a second volume expansion and phase change into a gaseous refrigerant. Through this, the second buffer can prevent the liquid refrigerant from flowing into the thrust bearing.

[0065] A third buffer is provided between the inner surface of the second bearing housing and the outer surface of the rotating shaft. The third buffer can cause a second volume expansion of the liquid refrigerant passing through the journal cooling path, thereby changing its phase into a gaseous refrigerant. Through this, the third buffer can prevent the liquid refrigerant from flowing into the thrust bearing and the journal bearing.

[0066] Fourth, a thrust communication channel is formed concavely inside the bearing housing to communicate with the thrust bearing. The thrust communication channel extends in the circumferential direction. A plurality of thrust communication channel outlets are formed penetratingly inside the bearing housing to communicate with the thrust communication channel and the internal space of the housing. The plurality of thrust communication channel outlets can discharge the refrigerant that has passed through the thrust bearing from the thrust communication channel into the internal space of the housing.

[0067] Through this, the thrust channel circulates the refrigerant introduced into the interior of the bearing housing from the inlet in a circumferential direction and discharges it into the internal space of the housing through the thrust channel outlet, thereby minimizing the flow resistance of the refrigerant without causing it to stagnate in one place.

[0068] Housing communication channels are formed to penetrate the interior of the bearing housing to communicate with the bearing. The housing communication channels are spaced apart in the circumferential direction. Multiple housing communication channels are connected to communicate with the bearing and the internal space of the housing. Through this, the thrust communication channels discharge the refrigerant introduced into the interior of the bearing housing into the internal space of the housing, thereby minimizing the flow resistance of the refrigerant without causing the refrigerant to stagnate in one place.

[0069] FIG. 1 is a conceptual diagram showing a cross-section of a turbo compressor according to one embodiment of the present invention.

[0070] Figure 2 is a conceptual diagram showing the cooling channel formed to supply constant pressure refrigerant to the bearing in Figure 1.

[0071] Figure 3 is a conceptual diagram showing the bump foil bearing installed in the bearing housing in Figure 1.

[0072] Figure 4 is a conceptual diagram showing the cooling channel formed inside the bearing housing in Figure 2.

[0073] Figure 5 is a conceptual diagram showing a cooling channel formed on one side of the bearing housing based on the axial centerline of the rotation axis in Figure 4.

[0074] FIG. 6 is a conceptual diagram showing various embodiments according to the number of cooling channels and thrust channel outlets in FIG. 4.

[0075] Figure 7 is a conceptual diagram showing the movement path of the refrigerant in Figure 3.

[0076] Figure 8 is a conceptual diagram showing the movement path of the refrigerant in Figure 2.

[0077] Figure 9 is a graph showing the flow rate according to the width of the thrust channel in Figure 5.

[0078] Hereinafter, a thrust bearing according to an embodiment of the present invention and a turbo compressor equipped with the same will be described in detail with reference to the attached drawings.

[0079] In the following description, descriptions of some components may be omitted to clarify the features of the present invention.

[0080] 1. Definition of Terms

[0081] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0082] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0083] As used in this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0084] In the following description, the term “turbo compressor” can be understood as a concept referring to a device that compresses gases, such as refrigerants, by rotating an impeller using power such as an electric motor.

[0085] In the following description, “radial” or “radial” refers to a shape extending outward from a central point like spokes of a wheel.

[0086] In the following description, “axial direction” refers to the longitudinal direction of the axis of rotation.

[0087] In the following description, the term “radial direction” refers to the longitudinal direction of a line segment extending from the center of a circle or cylinder to a point on the circumference.

[0088] In the following description, “circumferential direction” refers to the direction of the circumference.

[0089] 2. Description of the configuration of a turbo compressor according to an embodiment of the present invention

[0090] FIG. 1 is a conceptual diagram showing a cross-section of a turbo compressor according to one embodiment of the present invention.

[0091] FIG. 2 is a conceptual diagram showing the cooling passage (143, 144) formed to supply a constant pressure refrigerant to the bearing in FIG. 1.

[0092] FIG. 3 is a conceptual diagram showing the bump foil bearing installed in the bearing housing (132) in FIG. 1.

[0093] FIG. 4 is a conceptual diagram showing the cooling channels (143, 144) formed inside the bearing housing (132) in FIG. 2.

[0094] FIG. 5 is a conceptual diagram showing a cooling channel (143, 144) formed on one side of the bearing housing (132) with respect to the axial centerline of the rotation axis (117) in FIG. 4.

[0095] FIG. 6 is a conceptual diagram showing various embodiments according to the number of cooling channels (143, 144) and thrust channel outlets (1451) in FIG. 4.

[0096] Figure 7 is a conceptual diagram showing the movement path of the refrigerant in Figure 3.

[0097] Figure 8 is a conceptual diagram showing the movement path of the refrigerant in Figure 2.

[0098] FIG. 9 is a graph showing the flow rate according to the width (W) of the thrust channel (145) in FIG. 5.

[0099] Hereinafter, each configuration of a turbo compressor according to an embodiment of the present invention will be described with reference to the attached drawings.

[0100] The turbo compressor according to the present invention comprises at least one of a housing (100), a motor unit (110), a rotating shaft (117), and an impeller (119).

[0101] The housing (100) may be formed in a cylindrical shape. The housing (100) may form the exterior or outer periphery of the turbo compressor.

[0102] A receiving space is formed inside the housing (100) to accommodate the electric motor (110).

[0103] A motor support portion is formed on the inner surface of the housing (100). A stator core (112), which will be described later, can be press-fitted and coupled to the motor support portion. One end of the motor support portion may be formed with a step in the radial direction of the housing (100). The motor support portion may be located in the center in the longitudinal direction of the housing (100).

[0104] Through this, the stator core (112) can be restricted from moving axially while supported at one end of the motor support.

[0105] The housing (100) extends in the axial direction of the rotation axis (117). Both ends of the housing (100) are formed to be open in the axial direction.

[0106] An impeller casing (124), which will be described later, can be attached to both ends of the housing (100).

[0107] The rotation axis (117) extends axially. The rotation axis (117) may be positioned to cross the radial center of the housing (100) axially.

[0108] The electric motor (110) includes a stator (111) and a rotor (114). The stator (111) is equipped with a stator core (112) and a stator coil (113). The stator core (112) can be formed in a cylindrical shape by laminating and combining a plurality of electrical steel plates.

[0109] A plurality of teeth may be formed on the inner side of the stator core (112) so as to protrude radially inward toward the rotation axis (117). A plurality of slots may be formed between the plurality of teeth. The plurality of teeth and the plurality of slots may be alternately arranged in the circumferential direction of the stator core (112) and may be spaced apart in the circumferential direction.

[0110] The stator coil (113) is wound onto the stator core (112) through a slot.

[0111] When power is applied to the stator coil (113), a magnetic field is generated around the stator coil (113).

[0112] The rotor (114) is positioned inside the stator (111). The rotor (114) is positioned spaced apart from the stator (111) by an air gap. The rotor (114) is mounted on a rotation axis (117) so as to be rotatable relative to the stator (111).

[0113] The rotor (114) may be configured to include a rotor core (115) and a permanent magnet (116). The rotor core (115) may be rotatably mounted together with the rotation axis (117) or omitted. If the rotor core (115) is omitted, the permanent magnet (116) may be mounted on the rotation axis (117). In this embodiment, the rotor core (115) is shown rotatably mounted together with the rotation axis (117).

[0114] The permanent magnet (116) may be received inside the rotor core (115) or mounted on the outer surface of the rotor core (115). When the permanent magnet (116) is received inside the rotor core (115), a plurality of magnet receiving holes may be formed to penetrate axially inside the rotor core (115).

[0115] In this embodiment, a plurality of permanent magnets (116) are shown mounted on the outer surface of the rotor core (115). The plurality of permanent magnets (116) may be spaced apart in the circumferential direction along the outer surface of the rotor core (115).

[0116] The permanent magnet (116) may be extended in the axial direction. The permanent magnet (116) may be extended in the radial direction. The radially inner end of the permanent magnet (116) may be coupled to contact the outer surface of the rotation axis (117). The radially outer end of the permanent magnet (116) may be coupled to contact the inner surface of the rotor core (115).

[0117] A rotor support is formed in the center of the rotation axis (117). The rotor support may have a length equal to the length of the permanent magnet (116). The rotor support may have a length equal to the length of the rotor core (115).

[0118] The permanent magnet (116) is mounted on the rotor core (115) and can be supported by the rotor core (115).

[0119] Bearing support members may be provided on both sides of the rotating shaft (117) with the rotor support member of the rotating shaft (117) in between. The bearing support members may be composed of a first bearing support member and a second bearing support member.

[0120] The first bearing support may extend axially from one end of the rotor support. The second bearing support may extend axially from the other end of the rotor support.

[0121] The diameters of the first bearing support and the second bearing support can each be formed to be smaller than the diameter of the rotor support.

[0122] A plurality of end rings can be attached to each end of the rotor core (115). The end rings can be mounted and attached to the rotation axis (117).

[0123] The end ring may consist of a first end ring (116a) and a second end ring (116b).

[0124] The first end ring (116a) can be mounted and coupled to one end of the rotor support. The first end ring (116a) can be positioned to face the axial end of the permanent magnet (116). By doing so, the first end ring (116a) can restrict the permanent magnet (116) from moving axially away from the rotor support.

[0125] The second end ring (116b) can be mounted and coupled to the other end of the rotor support. The second end ring (116b) can be positioned to face the axial other end of the permanent magnet (116). By doing so, the second end ring (116b) can restrict the permanent magnet (116) from moving axially away from the magnet support.

[0126] The rotation shaft (117) is configured to rotate together with the rotor (114) and transmit rotational force to the impeller (119) to be described later.

[0127] The impeller (119) is configured to suck in a working fluid such as a refrigerant. The impeller (119) may be configured to include a hub (121) and a plurality of blades (122).

[0128] A through hole is provided axially to allow the rotation axis (117) to pass through the inside of the hub (121). The hub (121) may be formed in a conical shape.

[0129] The outer surface of the hub (121) may be formed to be inclined with respect to the axial direction. The diameter of the hub (121) may be formed to increase from the upstream side to the downstream side with respect to the suction direction of the working fluid.

[0130] The blade (122) may be formed to protrude along a spiral from the outer surface of the hub (121). A plurality of blades (122) are spaced apart in the circumferential direction of the hub (121).

[0131] The impeller (119) can be configured to discharge the working fluid sucked in axially in the radial direction of the impeller (119).

[0132] The impeller (119) may be composed of a first impeller (120a) to an Nth impeller depending on the refrigerant compression process. In this embodiment, the configuration is shown as being composed of a first impeller (120a) and a second impeller (120b). The first impeller (120a) may be named a first-stage impeller (119). The second impeller (120b) may be named a second-stage impeller (119).

[0133] Unless the first impeller (120a) and the second impeller (120b) are separately distinguished in this specification, the description of the configuration of the impeller (119) may be applied to the first impeller (120a) and the second impeller (120b).

[0134] Working fluids such as refrigerant and / or air can be compressed once in the first impeller (120a) and then flow into the second impeller (120b) to be compressed twice.

[0135] According to this configuration, the turbo compressor can compress the refrigerant in multiple stages depending on the number of impellers (119). In this embodiment, a configuration of a two-stage compressor is shown.

[0136] A first impeller support and a second impeller support may be provided at both ends of the rotating shaft (117).

[0137] The first impeller support has a diameter smaller than the diameter of the first bearing support of the rotating shaft (117). The first impeller support may be formed to protrude axially from one end of the rotating shaft (117). The first impeller support may be press-fitted into the inside of the hub (121) of the first impeller (120a).

[0138] The second impeller support has a diameter smaller than the diameter of the second bearing support of the rotating shaft (117). The second impeller support may be formed to protrude axially from the other end of the rotating shaft (117). The second impeller support may be press-fitted into the inside of the hub (121) of the second impeller (120b).

[0139] The impeller casing (124) may be configured to include a first impeller casing (124a) and a second impeller casing (124b). The first impeller casing (124a) may be coupled to one side of the housing (100).

[0140] The first impeller casing (124a) can be coupled to one end of the housing (100) to cover one end of the housing (100).

[0141] The second impeller casing (124b) can be coupled to the other end of the housing (100) to cover the other end of the housing (100).

[0142] The configuration of the impeller casing (124) described below may be applied to the first impeller casing (124a) and the second impeller casing (124b) unless otherwise distinguished.

[0143] The impeller casing (124) may be configured to include a suction part (125a, 125b) and a diffuser casing (126a, 126b).

[0144] The suction portions (125a, 125b) may be formed in a cylindrical shape. The suction portions (125a, 125b) may be extended in the axial direction. The suction portions (125a, 125b) may be extended along the circumferential direction. A suction passage may be formed on the inner side of the suction portions (125a, 125b).

[0145] The diffuser casing (126a, 126b) extends radially outward from one end of the suction portion (125a, 125b) in the axial direction. The diffuser casing (126a, 126b) may extend along the circumferential direction. The suction portion (125a, 125b) and the diffuser casing (126a, 126b) are formed integrally with each other.

[0146] The impeller casing (124) includes an intake port (127a, 127b), a diffuser (128a, 128b), and a discharge port (129a, 129b). The intake ports (127a, 127b) are formed to penetrate axially through the center of the impeller casing (124). An impeller (119) can be accommodated inside the intake ports (127a, 127b).

[0147] Based on the suction direction of the working fluid, the diameter of the suction ports (127a, 127b) can be formed to decrease as it moves from the upstream side to the downstream side. Accordingly, the flow velocity of the refrigerant sucked through the suction ports (127a, 127b) can be increased.

[0148] The discharge ports (129a, 129b) may be provided on the outer periphery of the impeller casing (124). The discharge ports (129a, 129b) may extend radially from the diffuser (128a, 128b) to be described later. The discharge pipes (130a, 130b) may be formed to protrude outward from the outer periphery of the impeller casing (124).

[0149] One side of the discharge pipe (130a, 130b) is connected to the discharge port (129a, 129b). The other side of the discharge pipe (130a, 130b) may be connected to the outside of the impeller casing (124).

[0150] The discharge pipes (130a, 130b) may be composed of a first discharge pipe (130a) and a second discharge pipe (130b). The first discharge pipe (130a) may be connected to communicate with the first discharge port (129a) of the first impeller casing (124a).

[0151] One side of the second discharge pipe (130b) can be connected to the second discharge port (129b) of the second impeller casing (124b). The other side of the second discharge pipe (130b) can be connected to the refrigerant inlet of the condenser. Through this, the refrigerant compressed in two stages can be delivered to the condenser.

[0152] The other end of the first discharge pipe (130a) can be connected to the suction port (127a, 127b) of the second impeller casing (124b). The middle portion of the connecting pipe extending from one side of the first discharge pipe (130a) to the other side can be connected to the outlet port (102a, 102b) of the housing (100) to be described later.

[0153] The diffuser (128a, 128b) may be formed to be axially recessed in the downstream cross-section of the diffuser casing (126a, 126b) with respect to the flow direction of the working fluid sucked into the impeller (119). The diffuser (128a, 128b) is formed on the inner side of the diffuser casing (126a, 126b). The diffuser (128a, 128b) is positioned between the intake port (127a, 127b) and the discharge port (129a, 129b).

[0154] The diffuser (128a, 128b) can be formed to extend in a spiral direction from the intake port (127a, 127b). The diffuser (128a, 128b) is connected to the discharge port (129a, 129b). The diffuser (128a, 128b) is formed so that the size (cross-sectional area) of the flow path increases as it goes from the intake port (127a, 127b) to the discharge port (129a, 129b).

[0155] According to this configuration, the working fluid sucked in by the rotation of the impeller (119) passes through the diffusers (128a, 128b), and the pressure of the working fluid increases. The diffusers (128a, 128b) can increase the pressure of the refrigerant by converting the kinetic energy of the working fluid sucked in by the impeller (119) into pressure energy.

[0156] The discharge ports (129a, 129b) of the first impeller casing (124a) can be connected to the suction ports (127a, 127b) of the second impeller casing (124b). Through this, the working fluid can be compressed by the first diffuser (128a) of the first impeller casing (124a), then sucked into the second diffuser (128b) of the second impeller casing (124b) and recompressed.

[0157] In order to prevent the refrigerant compressed by the diffuser (128a, 128b) from flowing back or leaking into the impeller (119), a sealing portion may be provided between the downstream end of the impeller (119) and the bearing housing (132) to be described later.

[0158] A sleeve (123) may be further provided on the hub (121) of the impeller (119). The sleeve (123) may extend axially from one end of the hub (121). The sleeve (123) may be provided at the downstream end of the hub (121) with respect to the flow direction of the working fluid sucked in by the impeller (119).

[0159] The sleeve (123) can be formed in a cylindrical shape.

[0160] The sleeve (123) is formed to wrap around the impeller support of the rotation shaft (117). The sleeve (123) is coupled to the impeller support. Through this, the sleeve (123) can rotate together with the impeller support.

[0161] The sealing portions (131a, 131b) may be provided on one side of the first bearing housing (132a) or the third bearing housing (132c) to be described later. Here, one side of the first bearing housing (132a) is positioned toward the first impeller casing (124a). One side of the third bearing housing (132c) is positioned toward the second impeller casing (124b).

[0162] The sealing portions (131a, 131b) may be composed of a plurality of sealing protrusions. The plurality of sealing protrusions are formed to protrude axially toward the impeller (119) from one surface of the first bearing housing (132a) or the third bearing housing (132c). The plurality of sealing protrusions may be spaced apart in the radial direction.

[0163] A plurality of sealing protrusions may be arranged with an axial gap between the rear surface of the hub (121) of the impeller (119). The rear surface of the hub (121) is positioned toward one side of the first bearing housing (132a) or the third bearing housing (132c). The rear surface of the hub (121) refers to the downstream end of the hub (121) with respect to the flow direction of the refrigerant passing through the impeller (119).

[0164] Through this, the plurality of sealing protrusions can seal the gap (gap) between the rear surface of the hub (121) of the impeller (119) and one surface of the first bearing housing (132a) or the third bearing housing (132c).

[0165] The sealing portion (131a, 131b) may include a first sealing portion (131a) and a second sealing portion (131b). The first sealing portion (131a) may be positioned between the first impeller (120a) and the first bearing housing (132a). The second sealing portion (131b) may be positioned between the second impeller (120b) and the third bearing housing (132c).

[0166] A bearing housing (132) is provided inside the housing (100). The bearing housing (132) is configured to support bearings. It includes a first bearing housing (132a), a second bearing housing (132b), and a third bearing housing (132c).

[0167] The first bearing housing (132a) is positioned on the inner side of one end of the housing (100). The first bearing housing (132a) is positioned toward the first impeller (120a) and the first impeller casing (124a). A first sealing portion (131a) may be provided on one surface of the first bearing housing (132a) positioned toward the first impeller (120a).

[0168] A bearing may be accommodated inside the bearing housing (132). A receiving portion may be formed on the inner side of the bearing housing (132) to accommodate the bearing. The first bearing housing (132a) may be provided with a first receiving portion (133a) to accommodate the first thrust bearing (135a) to be described later.

[0169] The first bearing housing (132a) may be formed in a cylindrical shape. The first bearing housing (132a) may include a first surface and a second surface. The first surface and the second surface may each be formed as a flat plane. The first surface and the second surface are arranged to face opposite directions in the axial direction. The thickness of the first bearing housing (132a) is formed between the first surface and the second surface.

[0170] A first sealing portion (131a) may be formed on the first surface of the first bearing housing (132a). A first receiving portion (133a) may be formed on the second surface of the first bearing housing (132a). The first receiving portion (133a) may be formed to be axially recessed from the second surface of the first bearing housing (132a) toward the first surface. A first thrust bearing (135a) may be mounted in the first receiving portion (133a).

[0171] The second bearing housing (132a) may be formed in a cylindrical shape. The first bearing housing (132a) and the second bearing housing (132b) may be arranged in contact with each other in the axial direction. The first bearing housing (132a) and the second bearing housing (132b) may be joined together.

[0172] The second bearing housing (132b) may include a first surface and a second surface. The first surface and the second surface may each be formed as a flat plane. The first surface and the second surface are arranged facing opposite directions in the axial direction. The second surface of the first bearing housing (132a) is arranged toward the first surface of the second bearing housing (132b). The thickness of the second bearing housing (132a) is formed between the first surface and the second surface of the second bearing housing (132a).

[0173] A second receiving portion (133b) may be provided on the first surface of the second bearing housing (132b). A second thrust bearing (135b), to be described later, may be received in the second receiving portion (133b). A second thrust bearing (135b) may be mounted in the second receiving portion (133b). The second receiving portion (133b) may be formed to be axially recessed from the first surface of the second bearing housing (132b) toward the second surface of the second bearing housing (132b).

[0174] The second bearing housing (132b) may be configured to include a first radial extension (1321) and a first axial extension (1322).

[0175] The first radial extension (1321) extends in the radial direction. The first radial extension (1321) may extend along the circumferential direction. The first radial extension (1321) may be formed in a cylindrical shape.

[0176] A second thrust bearing (135b) may be mounted on the first surface of the first radial extension (1321). A second receiving portion (133b) in which the second thrust bearing (135b) is mounted may be formed on the first surface of the first radial extension (1321).

[0177] The first surface of the first radial extension (1321) may be positioned toward the second surface of the first bearing housing (132a). The second surface of the first radial extension (1321) may be positioned toward the internal space of the housing (100). The second surface of the first radial extension (1321) may be positioned toward the transmission unit (110).

[0178] The first axial extension (1322) extends in the axial direction. The first axial extension (1322) may extend along the circumferential direction. The first axial extension (1322) may be formed in a cylindrical shape. The first axial extension (1322) is formed to surround the rotation axis (117). A first journal bearing (134a) may be mounted on the inner circumference of the first axial extension (1322).

[0179] The third bearing housing (132c) may be provided on the inner side of the other end of the housing (100). The third bearing housing (132c) may be positioned toward the second impeller casing (124b) and the second impeller (120b). The third bearing housing (132c) may be positioned between the second impeller (120b) and the electric motor (110).

[0180] The third bearing housing (132c) may be configured to include a second radial extension (1323) and a second axial extension (1324).

[0181] The second radial extension (1323) extends radially. The second radial extension (1323) may extend along the circumferential direction. The second radial extension (1323) may be formed in a cylindrical shape.

[0182] The first surface of the second radial extension (1323) may be positioned toward the internal space of the housing (100). The first surface of the second radial extension (1323) may be positioned toward the electric motor (110). The second surface of the second radial extension (1323) may be positioned toward the second impeller casing (124b) and the second impeller (120b).

[0183] The second axial extension (1324) extends in the axial direction. The second axial extension (1324) may extend along the circumferential direction. The second axial extension (1324) may be formed in a cylindrical shape. The second axial extension (1324) is formed to surround the rotation axis (117). A second journal bearing (134b) may be mounted on the inner surface of the second axial extension (1324).

[0184] The rotation axis (117) may be rotatably supported by a bearing. The bearing may be configured to include a journal bearing (134) and a thrust bearing (135).

[0185] The journal bearing (134) can be implemented as a fluid bearing such as a gas foil bearing. In this embodiment, the journal bearing (134) can be implemented as a fluid bearing such as an air bearing or a bump foil bearing. In this embodiment, the journal bearing (134) is shown configured as an air bearing.

[0186] The air bearing is formed in a cylindrical shape to surround the rotating shaft (117). The air bearing is positioned with a gap between it and the outer surface of the rotating shaft (117). Refrigerant can be supplied through the gap.

[0187] A gap may be formed between the inner surface of the journal bearing (134) and the outer surface of the bearing support of the rotation shaft (117). A refrigerant, which is the working fluid, may flow through the gap to form a fluid film.

[0188] Through this, the journal bearing (134) can support the radial load of the rotating shaft (117) by forming a preset pressure, i.e., static pressure, through the fluid film.

[0189] Additionally, the journal bearing (134) can limit the rotation axis (117) from moving radially.

[0190] The journal bearing (134) may be composed of a first journal bearing (134a) and a second journal bearing (134b). The first journal bearing (134a) is configured to support one side of the rotation axis (117).

[0191] The first journal bearing (134a) can be placed between the first impeller (120a) and the electric motor (110). The first journal bearing (134a) can be placed between the first impeller (120a) and the rotor (114).

[0192] The second journal bearing (134b) is configured to support the other side of the rotation shaft (117). The second journal bearing (134b) may be positioned between the second impeller (120b) and the transmission unit (110). The second journal bearing (134b) may be positioned between the second impeller (120b) and the rotor (114).

[0193] A unilateral axial load is applied to the rotation axis (117). A unilateral axial load refers to a load that acts in one direction along the axial direction. In this embodiment, the unilateral load can act axially from the second impeller (120b) toward the first impeller (120a).

[0194] When operating a two-stage compression turbo compressor, the pressure sucked into the second impeller (120b) is the pressure of the working fluid that is first compressed by the first impeller (120a) and the first diffuser (128a), so the pressure sucked into the second impeller (120b) is greater than the pressure sucked into the first impeller (120a).

[0195] Due to the difference in pressure between the working fluid sucked into the first impeller (120a) and the working fluid sucked into the second impeller (120b), a unilateral axial load can be applied from the second impeller (120b) toward the first impeller (120a).

[0196] A thrust runner (118) is provided on one side of the rotation shaft (117). The thrust runner (118) is formed to protrude radially outward from the outer surface of the rotation shaft (117). The thrust runner (118) may extend circumferentially along the circumference of the rotation shaft (117). The thrust runner (118) may be positioned between the first impeller (120a) and the first journal bearing (134a).

[0197] Through this, the thrust runner (118) can transmit an axial load to the thrust bearing (135).

[0198] The thrust runner (118) may include a first surface, a second surface and an outer surface.

[0199] The first and second surfaces of the thrust runner (118) are arranged to face each other in opposite directions in the axial direction. The first surface of the thrust runner (118) is flat. The first surface of the thrust runner (118) is arranged toward the second surface of the first bearing housing (132a). A portion of the thrust runner (118) may be received in the first receiving portion (133a) of the first bearing housing (132a).

[0200] The second surface of the thrust runner (118) is flat. The second surface of the thrust runner (118) is positioned toward the first surface of the second bearing housing (132b). The other part of the thrust runner (118) may be received in the second receiving portion (133b) of the second bearing housing (132b).

[0201] The outer surface of the thrust runner (118) is a circular curved surface connecting the first surface and the second surface. The thickness of the thrust runner (118) can be formed between the first surface and the second surface. A unilateral axial load can be applied to the first surface of the thrust runner (118).

[0202] In this embodiment, the thrust bearing (135) may be configured to include a first thrust bearing (135a) and a second thrust bearing (135b). However, the second thrust bearing (135b) may be omitted as necessary.

[0203] The first receiving portion (133a) of the first bearing housing (132a) and the second receiving portion (133b) of the second bearing housing (132b) are arranged to face each other in the axial direction. The first receiving portion (133a) and the second receiving portion (133b) can form a single receiving portion to accommodate the thrust runner (118).

[0204] The first thrust bearing (135a) can be mounted on a portion of the second surface of the first bearing housing (132a). The first thrust bearing (135a) can be received and mounted in the first receiving portion (133a) of the first bearing housing (132a). The first thrust bearing (135a) is positioned spaced apart from the first surface of the thrust runner (118) with a gap.

[0205] The second thrust bearing (135b) may be mounted on a portion of the first surface of the second bearing housing (132b). The second thrust bearing (135b) may be received and mounted in the second receiving portion (133b) of the second bearing housing (132b). The second thrust bearing (135b) is positioned spaced apart from the second surface of the thrust runner (118) with a gap.

[0206] The first impeller (120a) and the second impeller (120b) are positioned at both ends of the rotation shaft (117). A plurality of thrust bearings (135) and a plurality of journal bearings (134) may be positioned between the first impeller (120a) and the second impeller (120b).

[0207] The first thrust bearing (135a) and the second thrust bearing (135b) may be positioned between the first impeller (120a) and the first journal bearing (134a). The bearings may be positioned along the axial direction from the first impeller (120a) toward the second impeller (120b) in the order of the first thrust bearing (135a), the second thrust bearing (135b), the first journal bearing (134a), and the second journal bearing (134b).

[0208] Through this, the length of the rotating shaft (117) can be shortened. In addition, the length of the turbo compressor can be shortened to make it smaller.

[0209] The thrust bearing (135) can be implemented as an air bearing or a fluid bearing such as at least one bump foil bearing. In this embodiment, the thrust bearing (135) is shown implemented as a bump foil bearing.

[0210] The thrust bearing (135) is positioned with a gap between it and one side of the thrust runner (118).

[0211] The thrust bearing (135) may include a top foil (136) and a bump foil (137). The thrust bearing (135) may further include a base plate (138).

[0212] The top foil (136) is configured to cover the bump foil (137). The top foil (136) can form the exterior of the thrust bearing (135). The top foil (136) can form an axial surface of the thrust bearing (135).

[0213] The first surface of the top foil (136) may be positioned toward the first surface of the thrust runner (118). The second surface of the top foil (136) may be positioned toward the bump foil (137). A thickness of the top foil (136) may be formed between the first surface and the second surface of the top foil (136).

[0214] The top foil (136) may include a fixed portion (1361), an inclined portion (1362), and a flat portion (1363).

[0215] The fixed part (1361) can be fixed to the base plate (138) or bearing housing (132) by welding or an adhesive means such as an adhesive.

[0216] The inclined portion (1362) extends from the fixed portion (1361) toward the flat portion (1363). The inclined portion (1362) is formed to connect the fixed portion (1361) and the flat portion (1363). The inclined portion (1362) is formed to be inclined at a predetermined angle with respect to one surface of the base plate (138) or bearing housing (132).

[0217] The flat portion (1363) may come into contact with the bump foil (137). A thickness of the flat portion (1363) may be formed between the first surface and the second surface of the flat portion (1363). The first surface and the second surface of the flat portion (1363) each form a flat plane.

[0218] The first surface of the flat section (1363) may be positioned toward the thrust runner (118). The second surface of the flat section (1363) may be positioned toward the bump foil (137). The flat section (1363) may be positioned parallel to the thrust runner (118).

[0219] The fixed portion (1361), inclined portion (1362), and flat portion (1363) of the top foil (136) may have the same thickness.

[0220] The bump foil (137) may be configured to include a plurality of bump portions (1371) and a plurality of connecting portions (1372). One end of the bump foil (137) may be fixed to one surface of the base plate (138) or the bearing housing (132). At least one point or area of ​​the bump foil (137) may be fixed to the base plate (138) or the bearing housing (132).

[0221] The bump portion (1371) may be formed in a semicircular or arc shape. However, the bump portion (1371) is not limited to the above shape.

[0222] The bump portion (1371) has a curved surface with a preset curvature. The thickness of the bump portion (1371) is formed between the first surface and the second surface of the bump portion (1371). The thickness of the bump portion (1371) can be formed uniformly. The bump portion (1371) can be formed in a convex curved shape toward the top foil (136).

[0223] The first surface of the bump portion (1371) may be positioned toward the top foil (136). The second surface of the bump portion (1371) may be positioned toward the opposite direction to the first surface of the bump portion (1371). The second surface of the bump portion (1371) may be positioned toward the base plate (138) or the bearing housing (132).

[0224] A portion of the first surface of the bump portion (1371) may be in contact with the top foil (136). The bump portion (1371) is formed to be elastic. For example, a portion of the bump portion (1371) may be in contact with the top foil (136) to receive an axial load.

[0225] A portion of the bump portion (1371) can be elastically deformed by an axial load. When the axial load is released, a portion of the bump portion (1371) is restored to its original position and can maintain its original shape. Through this, the bump foil (137) can elastically support the top foil (136) using the elastic force of the bump portion (1371). The bump foil (137) can mitigate the impact transmitted from the rotation axis (117).

[0226] One area of ​​the first surface of the bump portion (1371) may be located at the highest height relative to the connecting portion (1372). Another area different from the one area of ​​the first surface of the bump portion (1371) may be located closer to the connecting portion (1372) than the said one area relative to the connecting portion (1372).

[0227] The connecting portion (1372) is formed to connect one end of two adjacent bump portions (1371) along the longitudinal direction of the bump foil (137). The connecting portion (1372) may be formed as a flat surface. The thickness of the connecting portion (1372) is formed between the first surface and the second surface of the connecting portion (1372).

[0228] The thickness of the connecting portion (1372) can be formed uniformly. The thickness of the bump portion (1371) and the connecting portion (1372) can be formed identically.

[0229] The first surface of the connecting portion (1372) may be positioned toward the top foil (136). The second surface of the connecting portion (1372) may be positioned toward the opposite direction to the first surface of the connecting portion (1372). The second surface of the connecting portion (1372) may be positioned toward the base plate (138) or the bearing housing (132).

[0230] The base plate (138) may be formed in a flat shape. A thickness of the base plate (138) may be formed between the first surface and the second surface of the base plate (138). The first surface of the base plate (138) may be positioned toward the bump foil (137). The second surface of the base plate (138) may be positioned toward the bearing housing (132). The base plate (138) may be formed in a circular shape.

[0231] The base plate (138) can be divided into N equal parts (N is a natural number greater than or equal to 2) of a 360-degree circle. Multiple bump foils (137) and top foils (136) can be formed in a fan shape. Multiple bump foils (137) and top foils (136) can be arranged in a circumferentially spaced manner in each circumferential section of the divided base plate (138).

[0232] Multiple top foils (136) can be configured to cover each of the multiple bump foils (137).

[0233] The thrust bearing (135) can form a gap (G) between the thrust runner (118) and the top foil (136). Refrigerant at a preset pressure can be supplied to the gap (G). The refrigerant can be supplied from outside the housing (100). A portion of the refrigerant discharged from the condenser of the refrigeration cycle can be supplied to the gap (G).

[0234] A portion of the refrigerant discharged from the above condenser can be supplied to the bearings of the turbo compressor and used as the working fluid for the bearings. In addition, the refrigerant condensed in the condenser may also serve to cool the heat generated in the bearings.

[0235] An inlet port (101a, 101b) and an outlet port (102a, 102b) are provided in the housing (100). The inlet port (101a, 101b) is formed to penetrate radially on one side of the housing (100). The inlet port (101a, 101b) can be connected to the refrigerant outlet of the condenser by a refrigerant inlet pipe.

[0236] Through this, the refrigerant condensed in the condenser can be introduced into the interior of the housing (100) through the inlet ports (101a, 101b).

[0237] Inlets (101a, 101b) may be provided in multiple numbers. The multiple inlets (101a, 101b) may consist of a first inlet (101a) and a second inlet (101b). The first inlet (101a) may be placed at one end of the housing (100). The second inlet (101b) may be placed at the other end of the housing (100).

[0238] A buffer (139) is provided inside the housing (100). The buffer (139) is formed to be larger than the cross-sectional area of ​​the inlets (101a, 101b). The flow cross-sectional area of ​​the buffer (139) perpendicular to the flow direction of the refrigerant is larger than the flow cross-sectional area of ​​the inlets (101a, 101b).

[0239] The buffer (139) has a large volume space relative to the inlets (101a, 101b). The buffer (139) may be formed in the shape of a circular ring or cylinder. The buffer (139) is connected to the inlets (101a, 101b) in communication. The buffer (139) can induce a phase change of the refrigerant condensed in the condenser through the inlets (101a, 101b).

[0240] For example, the refrigerant condensed in the condenser may include gaseous refrigerant and liquid refrigerant. The buffer (139) can expand the volume of the liquid refrigerant to change its phase into gaseous refrigerant.

[0241] Through this, the buffer (139) can prevent liquid refrigerant from flowing into the interior of the compressor. In particular, the buffer (139) can block the supply of liquid refrigerant to the bearing.

[0242] The buffer (139) includes first buffers (140a, 140b). The first buffers (140a, 140b) may be disposed between the housing (100) and the bearing housing (132). The first buffers (140a, 140b) may be provided in multiple numbers. One of the first buffers (140a, 140b) is provided inside one end of the housing (100). Another of the first buffers (140b) is provided inside the other end of the housing (100).

[0243] The first buffer (140a, 140b) extends circumferentially along the inner circumference of the housing (100). The first buffer (140a, 140b) extends circumferentially along the outer circumference of the bearing housing (132). One side of the outer surface of the first buffer (140a, 140b) communicates with the inlet (101a, 101b). The first buffer (140a, 140b) surrounds the bearing housing (132).

[0244] The first buffer (140a, 140b) includes a first surface, a second surface, an outer surface, and an inner surface. The first surface of the first buffer (140a, 140b) is positioned toward the impeller casing (124). The first surface of the first buffer (140a, 140b) is configured to be covered by the impeller casing (124).

[0245] The second surface of the first buffer (140a, 140b) is positioned facing opposite to the impeller casing (124). The second surface of the first buffer (140a, 140b) is configured to be covered by one end of the housing (100).

[0246] A flange portion (103) is formed at each end of the housing (100) to protrude radially. A stator core (112) is press-fitted to the inner surface of the central portion of the housing (100). The inner diameter of the flange portion (103) is larger than the inner diameter of the central portion of the housing (100).

[0247] The outer diameter of the bearing housing (132) is larger than the inner diameter of the central part of the housing (100). The inner diameter of the bearing housing (132) is larger than the outer diameter of the bearing support part of the rotation shaft (117). The outer and inner diameters of the first bearing housing (132a) and the second bearing housing (132b) may be the same.

[0248] The first buffer (140a, 140b) is provided on the inner side of the flange portion (103). The second surface of the first buffer (140a, 140b) is configured to be covered by the inner surface of the flange portion (103) adjacent to the inner circumferential surface of the flange portion (103).

[0249] Cooling channels (143, 144) are provided inside the bearing housing (132). The cooling channels (143, 144) may be formed to penetrate radially inside the bearing housing (132). The cooling channels (143, 144) are configured to supply refrigerant that has passed through the first buffer (140a, 140b) to the bearing.

[0250] The cooling channels (143, 144) include a thrust cooling channel (143) and a journal cooling channel (144a, 144b).

[0251] The thrust cooling channel (143) is provided inside the first bearing housing (132a). The thrust cooling channel (143) may be formed to penetrate radially inside the first bearing housing (132a). The outer end of the thrust cooling channel (143) is connected to communicate with the first buffer (140a, 140b).

[0252] The inner end of the thrust cooling channel (143) is connected to communicate with the thrust bearing (135). In particular, the inner end of the thrust cooling channel (143) may be connected to communicate with the first thrust bearing (135a). The inner end of the thrust cooling channel (143) may be connected to communicate with the first receiving portion (133a).

[0253] Through this, the thrust cooling channel (143) can supply refrigerant to the thrust bearing (135).

[0254] The thrust cooling channels (143) are provided in multiple numbers. The multiple thrust cooling channels (143) may be spaced apart in the circumferential direction of the first bearing housing (132a).

[0255] The journal cooling channel (144a, 144b) may include a first journal cooling channel (144a) and a second journal cooling channel (144b).

[0256] The first journal cooling channel (144a) is provided inside the second bearing housing (132b). The first journal cooling channel (144a) may be formed to penetrate radially inside the second bearing housing (132b). The outer end of the first journal cooling channel (144a) is connected to communicate with the first buffer (140a).

[0257] The inner end of the first journal cooling channel (144a) can be connected to the first journal bearing (134a).

[0258] Through this, the first journal cooling channel (144a) can supply refrigerant to the first journal bearing (134a).

[0259] The inner end of the first journal cooling channel (144a) may be connected to communicate with the second receiving portion (133b). The inner end of the first journal cooling channel (144a) may also be connected to communicate with the thrust bearing (135). In particular, the inner end of the first journal cooling channel (144a) may be connected to communicate with the second thrust bearing (135b).

[0260] The first journal cooling passage (144a) is provided in multiple numbers. The multiple first journal cooling passages (144a) may be spaced apart in the circumferential direction of the second bearing housing (132b).

[0261] The second journal cooling channel (144b) is provided inside the third bearing housing (132c). The second journal cooling channel (144b) may be formed to penetrate radially inside the third bearing housing (132c). The outer end of the second journal cooling channel (144b) is connected to communicate with the first buffer (140b).

[0262] The inner end of the second journal cooling channel (144b) can be connected to the second journal bearing (134b).

[0263] Through this, the second journal cooling channel (144b) can supply refrigerant to the second journal bearing (134b).

[0264] The second journal cooling passage (144b) is provided in multiple numbers. The multiple second journal cooling passages (144b) may be spaced apart in the circumferential direction of the third bearing housing (132c).

[0265] Through this, as the number of cooling channels (143, 144) increases, the amount of refrigerant supplied to the bearing increases, and the temperature of the bearing decreases, thereby improving the cooling performance of the bearing.

[0266] The buffer (139) may further include a second buffer (141). The second buffer (141) may be provided inside the first bearing housing (132a). The second buffer (141) may be connected to communicate with the thrust cooling channel (143). The second buffer (141) is formed with a cross-sectional area larger than that of the thrust cooling channel (143).

[0267] The second buffer (141) may be formed to be smaller than or equal to the inner diameter of the first bearing housing (132a). The second buffer (141) may be formed in a cylindrical or ring shape. The second buffer (141) may be configured to surround the bearing support of the rotation shaft (117).

[0268] The second buffer (141) may be positioned between the first bearing housing (132a) and the rotation axis (117). The second buffer (141) may be formed to be radially recessed from the outer surface of the rotation axis (117).

[0269] The second buffer (141) may be extended in the axial and circumferential directions. The axial width of the second buffer (141) is smaller than the axial width of the first buffer (140a, 140b). The axial width of the second buffer (141) may be formed to be equal to the axial width of the first bearing housing (132a).

[0270] The second buffer (141) may be connected to communicate with the downstream end of the thrust cooling channel (143) based on the flow direction of the refrigerant. One side of the second buffer (141) may be connected to communicate with the inner end of the first thrust bearing (135a). One side of the second buffer (141) may be connected to communicate with the first receiving portion (133a).

[0271] Through this, the second buffer (141) can prevent liquid refrigerant from flowing into the first thrust bearing (135a) by secondarily expanding the volume of the refrigerant supplied from the thrust cooling channel (143).

[0272] The buffer (139) may further include a third buffer (142a, 142b). The third buffer (142a, 142b) may be provided inside the second bearing housing (132b). The third buffer (142a, 142b) may be connected to communicate with the journal cooling passage (144a, 144b). The cross-sectional area of ​​the third buffer (142a, 142b) is formed to be larger than the cross-sectional area of ​​the journal cooling passage (144a, 144b).

[0273] The third buffer (142a) may be formed to be smaller than or equal to the inner diameter of the second bearing housing (132b). The third buffer (142a, 142b) may be formed in a cylindrical or ring shape. The third buffer (142a, 142b) may be configured to surround the bearing support of the rotation shaft (117).

[0274] The third buffer (142a) may be positioned between the second bearing housing (132b) and the rotation axis (117). The third buffer (142a, 142b) may be formed to be radially recessed from the outer surface of the rotation axis (117).

[0275] The third buffer (142a, 142b) may be extended in the axial and circumferential directions. The axial width of the third buffer (142a, 142b) is smaller than the axial width of the first buffer (140a, 140b). The axial width of the third buffer (142a, 142b) may be formed to be equal to the axial width of the first bearing housing (132a).

[0276] The third buffer (142a, 142b) can be connected to communicate with the downstream end of the journal cooling channel (144a, 144b) with respect to the direction of flow of the refrigerant. One side of the third buffer (142a, 142b) can be connected to communicate with one end of the first journal bearing (134a).

[0277] The other side of the third buffer (142a) may be connected to the second receiving portion (133b). The other side of the third buffer (142a) may be connected to the second thrust bearing (135b).

[0278] Through this, the third buffer (142a, 142b) can prevent liquid refrigerant from flowing into the first journal bearing (134a) or the second thrust bearing (135b) by secondarily expanding the volume of the refrigerant supplied from the journal cooling passage (144a, 144b).

[0279] Each third buffer (142a, 142b) may be provided in multiple numbers. One of the third buffers (142a, 142b) may be positioned between the second bearing housing (132b) and one end of the rotation shaft (117). The one third buffer (142a) may be formed to be recessed from the outer surface of one end of the rotation shaft (117).

[0280] Among the plurality of third buffers (142a, 142b), another third buffer (142b) may be positioned between the third bearing housing (132c) and the other end of the rotation shaft (117). The other third buffer (142b) may be formed to be recessed from the outer surface of the other end of the rotation shaft (117).

[0281] One of the plurality of third buffers (142a, 142b), the third buffer (142a), can be connected to communicate with the first journal cooling channel (144a) formed inside the second bearing housing (132b). The one third buffer (142a) can transfer vaporized refrigerant to the first journal bearing (134a).

[0282] Among the plurality of third buffers (142a, 142b), another third buffer (142b) can be connected to communicate with the second journal cooling channel (144b) formed inside the third bearing housing (132c). The other third buffer (142b) can deliver vaporized refrigerant to the second journal bearing (134b).

[0283] However, among the multiple third buffers (142a, 142b), the other third buffer (142b) can prevent liquid refrigerant from flowing into the second journal bearing (134b).

[0284] The bearing housing (132) may further include a thrust communication channel (145) and a thrust communication channel outlet (1451). The thrust communication channel (145) may be formed concavely outwardly in the radial direction from the outer end of the receiving portion of the bearing housing (132). In this embodiment, the thrust communication channel (145) may be provided in the second receiving portion (133b) of the second bearing housing (132b).

[0285] The thrust communication channel (145) may extend circumferentially along the circumference of the receiving portion of the bearing housing (132). The thrust communication channel (145) may be connected to the receiving portion.

[0286] The thrust communication channel outlet (1451) may be formed to penetrate axially into the second bearing housing (132b) on one side of the thrust communication channel (145). One side of the thrust communication channel outlet (1451) may be connected to communicate with the thrust communication channel (145). The other side of the thrust communication channel outlet (1451) may be connected to communicate with the internal space of the housing (100).

[0287] The thrust flue outlet (1451) may be provided in multiple numbers. The multiple thrust flue outlets (1451) may be spaced apart along the circumferential direction of the thrust flue (145).

[0288] Through this, the refrigerant passing through the thrust bearing (135) can circulate circumferentially along the thrust connecting passage (145). The refrigerant flowing along the thrust connecting passage (145) can be discharged into the internal space of the housing (100) through the thrust connecting passage outlet (1451).

[0289] The thrust connecting passage (145) and the thrust connecting passage outlet (1451) move the refrigerant in the order of the first buffer (140a), the thrust cooling passage (143), the second buffer (141), and the thrust bearing (135), and can smoothly discharge the refrigerant into the internal space of the housing (100).

[0290] In addition, the thrust channel (145) can minimize the flow resistance of the refrigerant by discharging the refrigerant into the internal space of the housing (100) through a plurality of thrust channel outlets (1451).

[0291] The refrigerant discharged into the internal space of the housing (100) can cool the electric motor (110), namely the stator (111) and rotor (114), which are housed in the internal space of the housing (100).

[0292] The thrust communication channel (145) can be connected to the downstream side of the thrust bearing (135) based on the direction of flow of the refrigerant. The smaller the axial width (W) of the thrust communication channel (145), the more likely a problem of refrigerant backflow may occur.

[0293] For example, when the axial width (W) of the thrust channel (145) is 0.3 mm or 0.5 mm, there is a problem that the flow rate of the refrigerant supplied to the thrust bearing (135) is small and the thrust bearing (135) cannot be sufficiently cooled (see FIG. 9).

[0294] As the axial width (W) of the thrust channel (145) increases, the flow rate of the refrigerant supplied to the thrust bearing (135) increases, thereby increasing the cooling performance of the thrust bearing (135).

[0295] The bearing housing (132) may further include a housing communication channel (146). The housing communication channel (146) may include a first housing communication channel (146a) and a second housing communication channel (146b).

[0296] The first housing communication channel (146a) may be formed to penetrate diagonally through the connection portion (1372) between the first radial extension portion (1321) and the first axial extension portion (1322) of the second bearing housing (132b). The first housing communication channel (146a) may be formed at an angle with respect to the first radial extension portion (1321) or the first axial extension portion (1322) of the second bearing housing (132b). One side of the first housing communication channel (146a) may be connected to communicate with the third buffer (142a). The other side of the first housing communication channel (146a) may be connected to communicate with the internal space of the housing (100).

[0297] The second housing communication channel (146b) may be formed to penetrate diagonally through the connection portion (1372) between the second radial extension portion (1323) and the second axial extension portion (1324) of the third bearing housing (132c). The second housing communication channel (146b) may be formed at an angle to the second radial extension portion (1323) or the second axial extension portion (1324) of the third bearing housing (132c). One side of the second housing communication channel (146b) may be connected to communicate with the third buffer (142b). The other side of the second housing communication channel (146b) may be connected to communicate with the internal space of the housing (100).

[0298] The housing communication channel (146) can be connected to the journal cooling channels (144a, 144b). The housing communication channel (146) can be connected to the upstream end of the journal cooling channels (144a, 144b) with respect to the direction of refrigerant flow.

[0299] The housing communication channel (146) can be connected to the thrust bearing (135). The housing communication channel (146) can be connected to the upstream end of the second thrust bearing (135b) based on the flow direction of the refrigerant passing through the journal cooling channels (144a, 144b).

[0300] The housing flue (146) allows the refrigerant flowing into the interior of the bearing housing (132) from the inlet (101a, 101b) to not stagnate in one place and to minimize the flow resistance of the refrigerant.

[0301] The thrust connecting passage (145) and the plurality of thrust connecting passage outlets (1451) allow the refrigerant introduced into the bearing housing (132) to circulate in a circumferential direction without stagnating in one place, thereby supplying the refrigerant evenly and smoothly to the bearing, which can minimize heat generation in the bearing.

[0302] The thrust flue (145), the plurality of thrust flue outlets (1451), and the housing flue (146) can indirectly cool the motor part (110) through the flue without directly supplying refrigerant to the motor part (110).

[0303] The outlets (102a, 102b) are formed to penetrate radially on the other side of the housing (100). The outlets (102a, 102b) may include a first outlet (102a) and a second outlet (102b). The first outlet (102a) is formed to penetrate one end of the housing. The second outlet (102b) is formed to penetrate the other end of the housing.

[0304] The outlets (102a, 102b) may be positioned facing in the opposite direction with a 180-degree gap along the circumferential direction from the inlets (101a, 101b). The outlets (102a, 102b) may be connected to the other side of the first discharge pipe (130a) by a refrigerant outlet pipe.

[0305] Through this, the refrigerant introduced through the inlet (101a, 101b) is used as the working fluid of the bearing, then flows out to the outside of the housing (100) through the outlet (102a, 102b), joins the first discharge pipe (130a), and can be introduced back into the second impeller (120b) together with the refrigerant that has been compressed by the first impeller (120a) and the first diffuser (128a).

[0306] Accordingly, according to the present invention, a first buffer (140a, 140b) is provided between the housing (100) and the bearing housing (132). An inlet (101a, 101b) is formed to penetrate the housing (100). Refrigerant condensed in the condenser can flow into the first buffer (140a, 140b) through the inlet (101a, 101b). The first buffer (140a, 140b) has a cross-sectional area larger than that of the inlet (101a, 101b). The first buffer (140a, 140b) extends circumferentially along the inner circumference of the housing (100). Through this, the first buffer (140a, 140b) expands the volume of the liquid refrigerant introduced through the inlet (101a, 101b) and vaporizes it into a gaseous refrigerant, thereby preventing the liquid refrigerant from entering the bearing.

[0307] A cooling channel (143, 144) is formed inside the bearing housing (132). The cooling channel (143, 144) is connected to the first buffer (140a, 140b). The cooling channel (143, 144) supplies a refrigerant introduced from the first buffer (140a, 140b) to the bearing, thereby minimizing heat generation in the bearing.

[0308] A thrust cooling channel (143) is formed to penetrate the interior of the first bearing housing (132a). A first journal cooling channel (144a) is formed to penetrate the interior of the second bearing housing (132b). A second buffer (141) is provided between the inner surface of the first bearing housing (132a) and the outer surface of the rotation shaft (117). The second buffer (141) can cause the liquid refrigerant passing through the thrust cooling channel (143) to undergo a secondary volume expansion and phase change into a gaseous refrigerant. Through this, the second buffer (141) can prevent the liquid refrigerant from flowing into the thrust bearing (135).

[0309] The third buffer (142a) is provided between the inner surface of the second bearing housing (132b) and the outer surface of the rotation shaft (117). The third buffer (142a) can cause the liquid refrigerant passing through the journal cooling passages (144a, 144b) to undergo a secondary volume expansion and phase change into a gaseous refrigerant. Through this, the third buffer (142a) can prevent the liquid refrigerant from flowing into the thrust bearing (135) and the journal bearing (134).

[0310] Additionally, a thrust communication channel (145) is formed concavely inside the bearing housing (132) to communicate with the thrust bearing (135). The thrust communication channel (145) extends in the circumferential direction. A plurality of thrust communication channel outlets (1451) are formed penetratingly inside the bearing housing (132) to communicate with the thrust communication channel (145) and the internal space of the housing (100). The plurality of thrust communication channel outlets (1451) can discharge the refrigerant that has passed through the thrust bearing (135) from the thrust communication channel (145) into the internal space of the housing (100).

[0311] By doing so, the thrust connecting passage (145) circulates the refrigerant introduced into the interior of the bearing housing (132) from the inlet (101a, 101b) in a circumferential direction and discharges it into the interior space of the housing (100) through the thrust connecting passage outlet (1451), thereby minimizing the flow resistance of the refrigerant without causing the refrigerant to stagnate in one place.

[0312] A housing communication channel (146) is formed to penetrate the interior of the bearing housing (132) to communicate with the bearing. The housing communication channels (146) are spaced apart in the circumferential direction. A plurality of housing communication channels (146) are connected to communicate with the bearing and the internal space of the housing (100). Through this, the thrust communication channel (145) discharges the refrigerant introduced into the interior of the bearing housing (132) into the internal space of the housing (100), thereby minimizing the flow resistance of the refrigerant without causing the refrigerant to stagnate in one place.

Claims

1. A housing having an inlet and an outlet; A rotating shaft rotatably provided inside the above housing; An impeller coupled to one end of the above-mentioned rotating shaft; A drive unit having a rotor coupled to the above-mentioned rotating shaft and a stator surrounding the rotor; and A bearing that rotatably supports the above-mentioned rotation axis; A cooling passage provided inside the above housing and supplying refrigerant introduced through the inlet to the bearing; and A buffer comprising a buffer that communicates with the above-mentioned inlet and has a cross-sectional area larger than that of the inlet and the cooling channel, Turbo compressor.

2. In Paragraph 1, The above buffer expands the volume of the liquid refrigerant introduced through the inlet and changes it into a gaseous refrigerant. Turbo compressor.

3. In Paragraph 1, It further includes a thrust runner formed to protrude radially from one side of the above-mentioned rotation axis, and The above bearing is, A thrust bearing spaced apart from one side of the thrust runner with a gap and supporting an axial load of the rotation shaft; and A journal bearing that is spaced apart from the outer surface of the aforementioned rotating shaft with a gap and supports the radial load of the said rotating shaft, Turbo compressor.

4. In Paragraph 3, The above buffer is, It includes a first buffer provided on the upstream side of the cooling channel with respect to the flow direction of the refrigerant, and which transmits the refrigerant introduced through the inlet to the cooling channel. The above cooling channel is, A thrust cooling passage communicating with the first buffer and the thrust bearing, and supplying a portion of the refrigerant vaporized in the first buffer to the thrust bearing; and A journal cooling path communicating with the first buffer and the journal bearing, and supplying another portion of the refrigerant vaporized in the first buffer to the journal bearing, Turbo compressor.

5. In Paragraph 4, The above buffer is, A second buffer further comprising a second buffer provided downstream of the thrust cooling channel with respect to the flow direction of the refrigerant and transferring the refrigerant that has passed through the thrust cooling channel to the thrust bearing. Turbo compressor.

6. In Paragraph 4, The above buffer is, A third buffer further comprising a downstream side of the journal cooling channel based on the flow direction of the refrigerant and transferring the refrigerant that has passed through the journal cooling channel to the journal bearing. Turbo compressor.

7. In Paragraph 4, The thrust bearing above is, A first thrust bearing spaced apart from one side of the thrust runner with a gap; and A second thrust bearing comprising a second thrust bearing spaced apart from the other surface of the thrust runner with a gap, facing in a direction opposite to one surface of the thrust runner with respect to the above axial direction, Turbo compressor.

8. In Paragraph 7, A bearing housing is provided inside the above housing, and The above bearing housing is, A first bearing housing having the thrust cooling channel inside and a first receiving portion formed recessed on one surface to accommodate the first thrust bearing and a portion of the thrust runner; and A second bearing housing comprising a journal cooling channel inside, and a second receiving portion formed to be recessed on one surface to accommodate the second thrust bearing and another part of the thrust runner, Turbo compressor.

9. In Paragraph 1, The above buffer extends in the circumferential direction of the rotation axis, Turbo compressor.

10. A housing having an inlet and an outlet formed for introducing external refrigerant; A rotating shaft rotatably provided inside the above housing; An impeller coupled to one end of the above-mentioned rotating shaft; A drive unit coupled to the above-mentioned rotating shaft and driving the above-mentioned impeller; A thrust runner formed to protrude radially from one side of the above-mentioned rotation axis; A bearing that rotatably supports the above-mentioned rotation axis; A bearing housing having a cooling passage provided inside the above housing and supplying a refrigerant introduced through the inlet to the bearing, and a receiving portion for accommodating the thrust runner; and A buffer comprising a buffer that communicates with the inlet and has a cross-sectional area larger than that of the inlet. Turbo compressor.

11. In Paragraph 10, The bearing housing is formed in a cylindrical shape, and the rotation axis penetrates the center of the bearing housing. The above buffer is, A first buffer disposed between the inner surface of the housing and the outer surface of the bearing housing and formed in a ring shape to surround the bearing housing, Turbo compressor.

12. In Paragraph 11, The above bearing is, A thrust bearing spaced apart from one side of the thrust runner with a gap and supporting an axial load of the rotation shaft; and It includes a journal bearing that is spaced apart from the aforementioned rotating shaft with a gap and supports the radial load of the said rotating shaft, and The above bearing housing is, A first bearing housing having a thrust cooling passage that communicates with the first buffer and the thrust bearing and supplies a portion of the refrigerant passing through the first buffer to the thrust bearing, and a first receiving portion that accommodates a portion of the thrust runner; and A second bearing housing comprising a journal cooling passage communicating with the first buffer and the journal bearing and supplying another portion of the refrigerant that has passed through the first buffer to the journal bearing, and a second receiving portion accommodating another portion of the thrust runner. Turbo compressor.

13. In Paragraph 12, The first and second bearing housings are each formed in a cylindrical shape and are arranged to be in contact with the axial direction of the rotation axis. The thrust cooling channel and the journal cooling channel are each provided in multiple numbers, and The plurality of thrust cooling channels are each formed to penetrate the first bearing housing in the radial direction, and The plurality of journal cooling channels are each formed to penetrate the second bearing housing in the radial direction. Turbo compressor.

14. In Paragraph 12, The thrust bearing above is, A first thrust bearing that is received in the first receiving portion and spaced apart from one surface of the thrust runner with a gap; and A second thrust bearing that is received in the second receiving portion and spaced apart from the other surface of the thrust runner with a gap, Turbo compressor.

15. In Paragraph 12, A thrust communication channel extending from the receiving portion to communicate with the thrust bearing; and A plurality of thrust communication channel outlets formed penetrating the interior of the bearing housing so as to communicate with the thrust communication channel and the interior space of the housing. Turbo compressor.

16. In Paragraph 12, The above bearing housing is, A radial extension formed radially to surround a portion of the thrust runner; and A axial extension portion extending axially from the inner end of the radial extension portion and formed in a cylindrical shape to surround the rotation axis, Turbo compressor.

17. In Paragraph 16, The journal bearing is disposed between the inner surface of the axial extension and the outer surface of the rotation axis. Turbo compressor.

18. In Paragraph 12, The above buffer is, A second buffer that communicates with the thrust cooling channel and the thrust bearing, is disposed between the inner surface of the first bearing housing and the outer surface of the rotation shaft, extends along the circumferential direction from the outer surface of the rotation shaft, and is formed as a recess; and A third buffer that is in communication with the journal cooling channel and the journal bearing, is disposed between the inner surface of the second bearing housing and the outer surface of the rotation shaft, extends along the circumferential direction from the outer surface of the rotation shaft, and is formed as a recess. Turbo compressor.

19. In Paragraph 18, A plurality of housing communication outlets that communicate with the internal space of the third buffer and the housing and are formed penetratingly in the inner side of the second bearing housing. Turbo compressor.

20. In Paragraph 10, The above impeller is, A first impeller coupled to one end of the above-mentioned rotating shaft; and It includes a second impeller coupled to the other end of the above-mentioned rotating shaft, and The above bearing is, A first journal bearing positioned toward the first impeller along the axial direction of the rotation axis with respect to the above-mentioned electric motor; A second journal bearing positioned toward the second impeller along the axial direction relative to the above-mentioned electric motor; and A thrust bearing disposed between the first impeller and the first journal bearing, Turbo compressor.

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