Turbo compressor

Abstract

The present invention provides a turbo compressor comprising: a housing; a rotary shaft; an impeller; and a shroud, which is provided on the inner periphery of the housing, accommodates the impeller such that the impeller is rotatably provided, and has, between the shroud and the impeller, a compression flow path through which a refrigerant flows while being compressed, wherein the impeller includes first and second impellers coupled to each of two sides of the rotary shaft, the shroud includes first and second shrouds for accommodating, respectively, the first and second impellers, the housing has a bypass path enabling the refrigerant that has passed through the compression flow path to flow by making a detour, and the bypass path communicates with one side of the second shroud such that the gap between the second impeller and the second shroud is adjusted.

Description

turbo compressor

[0001] The present invention relates to a turbocompressor, and more particularly, to a turbocompressor capable of adjusting the gap between a shroud and an impeller according to the operating speed of the turbocompressor.

[0002] Typically, compressors are used in vapor compression refrigeration cycles (hereinafter referred to as "refrigeration cycles"), such as refrigerators and air conditioners. Depending on the method of compressing the refrigerant, compressors can be categorized into reciprocating, rotary, and scroll types.

[0003] A reciprocating compressor is a compressor that compresses gas through the reciprocating motion of a piston inside a cylinder, and among these, a scroll compressor is a compressor in which a rotating scroll is engaged with a fixed scroll fixed in the internal space of a sealed container and rotates, thereby forming a compression chamber between the fixed wrap of the fixed scroll and the rotating wrap of the rotating scroll.

[0004] A turbocompressor is a type of centrifugal compressor. It compresses gas using centrifugal force by rotating a wheel with curved blades within a casing. Turbocompressors offer advantages over reciprocating and screw compressors, including larger capacity, lower noise, and lower maintenance. Furthermore, they can produce clean, oil-free compressed gas.

[0005] Turbocompressors are similar to turbo blowers, but have higher discharge pressure and lower flow rates. These turbocompressors increase the pressure of a continuously flowing fluid. They can be classified as axial-flow (if the fluid flows axially) or centrifugal (if the fluid flows radially).

[0006] A centrifugal turbocompressor consists of an impeller to compress gas and a diffuser to decelerate the accelerated gas flow and convert it into pressure. When a motor rotates the impeller at high speed, external gas is sucked along the impeller's axial direction and discharged in the centrifugal direction of the impeller. The fluid discharged in the centrifugal direction of the impeller travels along the flow path formed inside the turbocompressor and is compressed.

[0007] Meanwhile, unlike volumetric compressors such as reciprocating or rotary compressors, turbocompressors struggle to achieve the desired high pressure ratio in a single compression cycle, even with optimally designed rotating impeller blade shapes. Factors such as processability, mass production, and durability pose challenges. Therefore, multistage turbocompressors are known, featuring multiple impellers arranged axially to compress fluid in multiple stages.

[0008] Multistage turbocompressors are known to compress fluid in multiple stages, with multiple impellers installed on a rotating shaft on one side of the rotor or facing each other on opposite ends of the rotating shaft with the rotor in between. For convenience, the former can be categorized as a one-side type, and the latter as a both-end type.

[0009] A double-stage turbocompressor with two impeller stages has the first and second stages positioned opposite each other, centered around the motor. This configuration ensures mechanical stability by symmetrically arranging the impellers and journal bearings, which apply the load to the shaft. In particular, the thrust directions of the two impellers are opposite, which suppresses axial fluctuations to a certain degree, allowing for a reduction in the size of the thrust bearing and thus improving motor efficiency.

[0010] However, in the case of a double-ended type, complex and long pipes or fluid passages are required to connect multiple impellers, which not only complicates the structure of the compressor, but also causes pressure loss in the process of the compressed fluid from one impeller moving through a long passage to the other impeller, which can reduce compressor efficiency.

[0011] Patent Document 1 (US Patent Publication No. US2017 / 0343001 A1, Document Date: November 30, 2017) discloses a turbo compressor that can adjust a gap by supplying high-pressure air to a piston and pushing a shroud in the axial direction, and that can supply high-pressure air by branching from the discharge pressure of the compressor.

[0012] The turbocompressor in Patent Document 1 has a relatively slow response speed to restore the gap reduced by high pressure due to the lack of a spring. Furthermore, when pressure fluctuations occur at high pressure, interference between the shroud and the impeller may occur. If a spring were present, the spring force would also increase when the gap is narrowed, allowing it to respond to pressure fluctuations. Furthermore, high-pressure air must be used as discharge air to enable immediate gap adjustment without an additional sensor, but this structure is inadequate. Furthermore, in a two-stage compressor, the gap in the first stage widens due to the difference in thrust between the first and second stages, and the structure to compensate for this is also inadequate.

[0013] Patent document 2 (US Patent Publication No. US2017 / 0342995 A1, Document Date: November 30, 2017) discloses a turbocompressor in which a gap can be adjusted by pushing a shroud wall axially using an actuator, and when the actuator is operated, the shroud rotates circumferentially so that the shroud can move axially along a screw thread.

[0014] The turbo compressor of Patent Document 2 requires an additional sensor to adjust the gap, and since the gap is detected by the sensor and then adjusted by the actuator, there is a problem in that the gap adjustment speed is relatively slow compared to the method of adjusting using discharge pressure.

[0015] In addition, to adjust the gap, the shroud must rotate in the centrifugal direction, which poses difficulties in mechanical coupling and sealing design between the rotating and non-rotating parts, and the influence on the flow due to the shroud rotation may also be problematic.

[0016] Therefore, development of a structure capable of controlling the gap while minimizing interference between the shroud and the impeller and improving the gap control response speed is required.

[0017] The present invention has been devised to solve the above problems, and one object of the present invention is to provide a turbo compressor having a structure capable of adjusting the gap between a shroud and an impeller using high-pressure gas force.

[0018] Another object of the present invention is to provide a turbocompressor having a structure in which the gap can be immediately adjusted according to the operating speed without additional devices by using a design pressure close to the discharge pressure.

[0019] Another object of the present invention is to provide a turbocompressor having a structure that can prevent interference between an impeller and a shroud when the gap is reduced, and additionally improve the gap adjustment response speed.

[0020] In order to solve the above problem, the turbocompressor of the present invention comprises: a housing forming an exterior; a rotating shaft rotatably installed inside the housing; an impeller coupled to the rotating shaft and rotating; a shroud provided on the inner periphery of the housing and accommodating the impeller so that the impeller is rotatably installed, and having a compression path through which a refrigerant compressed between the impeller and the shroud flows; the impeller includes first and second impellers respectively coupled to both sides of the rotating shaft, and the shroud includes first and second shrouds accommodating the first and second impellers respectively, and the housing is provided with a bypass path through which the refrigerant passing through the compression path is allowed to flow, and the bypass path is connected to one side of the second shroud.

[0021] This allows the gap to be adjusted to the operating point of the turbo compressor without any additional sensors or devices by using the discharge pressure of the two-stage compression unit.

[0022] The above housing may be provided with a pressurized space that is connected to the compression path and enables pressurization of the second shroud.

[0023] Through the pressurized space, the second shroud is pressurized, and the gap can be instantly adjusted to the operating speed of the turbo compressor without any additional devices by using a design pressure close to the discharge pressure of the second-stage compression unit.

[0024] In the pressurized space, an elastic member that is elastically supported to provide elastic force between the housing and the second shroud may be installed.

[0025] By means of the elastic member, interference between the impeller and the shroud can be prevented when the gap between the impeller and the shroud is reduced.

[0026] Preferably, the elastic member is arranged parallel to the axial direction in which the rotation axis extends, and both ends can be fixed between one surface of the second shroud and one surface of the housing, respectively.

[0027] The pressurized space is formed in a circumferential direction on one side of the second shroud, and at least two elastic members are provided, and the at least two elastic members can be arranged to be spaced apart from each other in the circumferential direction.

[0028] By having at least two elastic members, it is possible to control the gap more stably.

[0029] The bypass flow path may include a first bypass flow path provided in parallel with the rotation axis in one side of the housing through which the refrigerant is discharged from the second impeller; a second bypass flow path formed in parallel with the first bypass flow path and communicating with one side of the second shroud; and a third bypass flow path provided between the first bypass flow path and the second bypass flow path.

[0030] This allows the refrigerant to flow through the first to third bypass passages to pressurize the second shroud, thereby allowing the gap between the impeller and the shroud to be adjusted.

[0031] The housing further includes one side on which the impeller is provided to compress and increase the refrigerant discharged from the impeller, and a diffuser formed radially from the one side to the other side, and the first bypass path can be branched between the one side of the housing on which the impeller is provided and the other side of the diffuser.

[0032] In this way, by using the optimal discharge pressure that is not completely diffused, clearance adjustment is possible at all operating points of the turbocompressor and interference between the impeller and shroud is prevented.

[0033] One side of the second shroud is provided so as to be parallel to the axial direction in which the rotation axis of the second shroud extends, and the housing may be provided with a guide surface portion connected to the one side so as to be parallel to the one side so as to enable the second shroud to move in the axial direction.

[0034] The second shroud is guided in its axial movement by a guide surface provided in the housing, enabling more stable gap adjustment.

[0035] The above housing may have a second shroud support portion that supports the second shroud so as to be relatively movable and has the guide surface portion on one side.

[0036] A guide support member may be provided between the above guide surface and the second shroud to guide axial movement of the second shroud.

[0037] By means of the guide support member, the second shroud can be stably moved in the axial direction.

[0038] The housing includes a motor housing having a motor room, and first and second impeller housings that respectively rotatably accommodate the first and second impellers, and the second shroud can be installed to be movable relative to the second impeller housing.

[0039] As the second shroud is installed in the second impeller housing, the gap with the second impeller can be adjusted.

[0040] The housing is provided with a pressurized space that is connected to the compression path and can pressurize the second shroud, and the second bypass path can be connected to the inside of the pressurized space.

[0041] The housing may include a motor housing having a motor room, and first and second impeller housings that rotatably accommodate the first and second impellers, respectively. A first flow path may be provided on one side of the first impeller housing to allow the refrigerant compressed in the first impeller to flow, a second flow path may be provided on the motor housing to provide the compressed refrigerant to the second impeller housing by communicating with the first flow path, and a third flow path may be provided on one side of the second impeller housing to provide the compressed refrigerant to the suction port of the second impeller.

[0042] Due to the structure in which the first to third ducts are provided in the housing, the overall size can be reduced compared to a structure using existing separate piping, and thus the packaging area can be reduced compared to a conventional turbo compressor.

[0043] The first impeller housing may be provided with a first flow path receiving projection that protrudes from one surface of the exterior and has the first flow path provided therein.

[0044] The first directional accommodating portion may include a first portion extending in a direction intersecting one surface of the exterior of the first impeller housing; and a second portion extending from an end of the first portion but formed into a curved surface.

[0045] The above motor housing may be provided with a second flow path receiving projection formed protruding from the outer periphery and having the second flow path provided therein.

[0046] The second impeller housing may be provided with a third flow path receiving projection formed protruding from one surface of the exterior and having the third flow path provided therein.

[0047] Due to this, the connection paths of the first compression section and the second compression section are integrated into the housing and the volute, and the method of fixing the first and second stage shells is changed, and the structure of the volute surrounding it can reduce the number of parts used, such as gaskets or O-rings, compared to the existing ones.

[0048] The turbo compressor of the present invention uses a design pressure close to the discharge pressure of a two-stage compression unit, so that the gap can be immediately adjusted according to the operating speed of the turbo compressor without any additional device.

[0049] The turbo compressor of the present invention can prevent interference between the impeller and the shroud when the gap is reduced by installing a spring.

[0050] The turbo compressor of the present invention can improve the gap adjustment response speed.

[0051] The turbo compressor of the present invention can increase efficiency by reducing the gap leakage of the turbo compressor by adjusting the axial position of the two-stage shroud so that the gap of the two-stage compression section does not increase.

[0052] The turbo compressor of the present invention uses the discharge pressure of a two-stage compression unit so that the gap can be adjusted according to the operating point of the turbo compressor without any additional sensors or devices.

[0053] In the turbo compressor of the present invention, since the gap between the second shroud and the second impeller in the two-stage compression section is adjusted, the difference between the gap between the first shroud and the first impeller in the one-stage compression section and the gap in the two-stage compression section becomes almost zero, so that the performance of the compressor can be further improved.

[0054] The turbo compressor of the present invention can prevent interference between a second impeller and a second shroud that may occur in a high-speed, high-pressure operating range by using an elastic member, and additionally can improve the gap control response speed by quickly restoring the shroud to its original position when the turbo compressor decelerates.

[0055] The turbo compressor of the present invention can reduce the overall size compared to a structure using a conventional separate pipe, so that the packaging area can be reduced compared to a conventional turbo compressor.

[0056] In addition, the turbo compressor of the present invention changes the method of fixing the first and second stage shells by integrating the connecting passages of the first compression section and the second compression section into the housing and the volute, and reduces the number of parts used, such as gaskets or O-rings, compared to existing ones, by using a structure in which the volute surrounds the first and second stage shells.

[0057] Figure 1 is a schematic diagram showing a refrigeration cycle device to which a turbo compressor according to the present invention is applied.

[0058] Figure 2 is a perspective view of the turbo compressor of the present invention viewed from one side.

[0059] Figure 3 is an exploded perspective view illustrating the turbo compressor of the present invention.

[0060] Fig. 4 is a cross-sectional view showing a turbo compressor of the present invention (part AA' of Fig. 2).

[0061] Figure 5 is an enlarged view of part A of Figure 4, viewed from a different part.

[0062] Figure 6 is a graph showing the optimal range of the spring constant K of an elastic member.

[0063] Figure 7 is a graph showing that the discharge intermediate pressure is applied at the static pressure position s matching the K value.

[0064] Figure 8 is a perspective view of another example of a turbo compressor of the present invention viewed from one side.

[0065] Figure 9 is an exploded perspective view showing another example of a turbo compressor of the present invention.

[0066] Fig. 10 is a cross-sectional view showing another example of a turbo compressor of the present invention (part BB' of Fig. 9).

[0067] Figure 11 is an enlarged view of part B of Figure 10.

[0068] Hereinafter, a turbo compressor according to the present invention will be described in detail with reference to an embodiment illustrated in the attached drawings. As conceptually illustrated in FIG. 1, in this embodiment, a double-ended, multi-stage turbo compressor is described as an example, in which a first impeller (151) and a second impeller (161) are installed at both ends of a rotating shaft (130), and an outlet of a first compression unit including the first impeller (151) is connected to an inlet of a second compression unit including the second impeller (161).

[0069] In addition, the turbo compressor according to the present embodiment can be applied to a chiller system that supplies cold water to a demand source or a refrigeration cycle system that uses a refrigerant.

[0070] In addition, in the turbo compressor according to the present embodiment, the longitudinal direction of the rotation shaft (130) is defined as the axial direction, the thickness direction of the rotation shaft (130) is defined as the radial direction, and the suction side of each impeller (151, 161) (or compression section) on the axial line is defined as the front, and the discharge side of each impeller (151, 161) is defined as the rear side, and the front side is defined as the first side, and the rear side is defined as the second side, respectively, and described.

[0071] In this specification, identical or similar reference numbers are assigned to identical or similar components even in different embodiments, and redundant descriptions thereof are omitted.

[0072] Additionally, even if the embodiments are different, a structure applied to one embodiment can be applied to another embodiment as long as there is no structural or functional contradiction.

[0073] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0074] In describing the embodiments disclosed in this specification, if it is determined that a detailed description of a related known technology may obscure the gist of the embodiments disclosed in this specification, the detailed description is omitted.

[0075] The attached drawings are only intended to facilitate understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

[0076] Figure 1 is a schematic diagram showing a refrigeration cycle including a turbo compressor according to the present embodiment.

[0077] Referring to Fig. 1, a refrigeration cycle device to which a turbo compressor according to the present embodiment is applied is configured such that a compressor (10), a condenser (20), an expander (30), and an evaporator (40) form a closed loop by a refrigerant circulation pipe (1a). That is, a condenser (20), an expander (30), and an evaporator (40) are sequentially connected to the discharge side of the compressor (10), and an outlet of the evaporator (40) is sequentially connected to the suction side of the compressor (10). Accordingly, the refrigerant compressed in the compressor (10) is discharged toward the condenser (20), and the refrigerant is sequentially passed through the condenser (20), the expander (30), and the evaporator (40) and is then sucked back into the compressor (10), repeating a series of processes.

[0078] Fig. 2 is a perspective view of the turbocompressor of the present invention as viewed from one side. Fig. 3 is an exploded perspective view illustrating the turbocompressor of the present invention. In addition, Fig. 4 is a cross-sectional view illustrating the turbocompressor of the present invention (part AA' of Fig. 2).

[0079] Hereinafter, a turbo compressor according to the present embodiment will be described with reference to FIGS. 2 to 4.

[0080] A turbo compressor according to the present embodiment includes a housing (110), a rotating shaft (130), an impeller (151, 161), and a shroud (1122, 1132).

[0081] The housing (110) according to the present embodiment forms the exterior of the turbo compressor.

[0082] The housing (110) accommodates components such as a rotating shaft (130) and an impeller (151, 161) described later.

[0083] In addition, the housing (110) is provided with a shroud (1122, 1132). The shroud (1122, 1132) accommodates an impeller (151, 161) and has a compression path (161a) through which compressed refrigerant flows between the impeller (151, 161). As described below, the shroud (1122, 1132) may be provided in the impeller housing (112, 113).

[0084] First, the housing (110) will be described.

[0085] The housing (110) may include a motor housing (111) in which the electric motor (120) is accommodated, a first impeller housing (112) in which the first impeller (151) is accommodated, and a second impeller housing (113) in which the second impeller (161) is accommodated.

[0086] In this embodiment, the housing (110) is provided with a bypass passage (1137) that allows the refrigerant passing through the compression passage (161a) to flow bypassing, as described below. The bypass passage (1137) is connected to one side of the second shroud (1132) so as to pressurize the second shroud (1132), thereby adjusting the gap between the second impeller (161) and the second shroud (1132).

[0087] This allows the shrouds (1122, 1132) to be quickly restored to their original positions when the turbo compressor decelerates, thereby improving the gap control response speed. By using a design pressure close to the discharge pressure of the second-stage compression unit, the gap can be instantly adjusted to match the operating speed of the turbo compressor without any additional devices.

[0088] As shown in Fig. 4, the bypass path (1137) and the second shroud (1132) can be provided in the second impeller housing (113).

[0089] The motor housing (111) may be formed in a cylindrical shape with both axial ends open. However, the two ends of the motor housing (111) may be formed with a first flange portion (1111) and a second flange portion (1112) extending radially to be connected to a first impeller housing (112) and a second impeller housing (113) to be described later.

[0090] A motor chamber (1114) may be formed inside the motor housing (111). A stator (121), which will be described later, may be press-fitted into the center of the motor chamber (1114). Accordingly, the motor chamber (1114) may be divided into a first space (first chamber) (1114a) toward the first compression unit (150) and a second space (second chamber) (1114b) toward the second compression unit (160) based on the stator (121), which will be described later.

[0091] A bearing support portion (1115), which forms part of a first bearing portion (141) to be described later, may be formed in the middle of the first space (1114a). The bearing support portion (1115) may extend radially toward the rotation axis (130) from the inner surface of the motor housing (111) forming the first space (1114a). However, the bearing support portion (1115) may also be press-fitted into the inner surface of the motor housing (111) or may be fastened using a fastening member (not shown) such as a bolt. An example in which the bearing support portion (1115) according to the present embodiment extends as a single body from the inner surface of the motor housing (111) is illustrated.

[0092] A bearing support portion (1115), which forms part of a first bearing portion (141) to be described later, may be formed in the middle of the first space (1114a). The bearing support portion (1115) may extend radially toward the rotation axis (130) from the inner surface of the motor housing (111) forming the first space (1114a). However, the bearing support portion (1115) may also be press-fitted into the inner surface of the motor housing (111) or may be fastened using a fastening member (not shown) such as a bolt. An example in which the bearing support portion (1115) according to the present embodiment extends as a single body from the inner surface of the motor housing (111) is illustrated.

[0093] A first radial bearing (145) may be installed between the first impeller shaft portion (132) and the first bearing shell (143). The first radial bearing (145) reduces radial stress between the first impeller shaft portion (132) and the first bearing shell (143), thereby ensuring bearing force. The first radial bearing (145) may be a journal bearing.

[0094] As described above, the second space (1114b) may be substantially connected to the first space (1114a). However, although not illustrated in the drawing, a separate refrigerant connection pipe (not illustrated) may be connected to the motor housing (111) forming the second space (1114b). Accordingly, a portion of the liquid refrigerant that has passed through the condenser (not illustrated) may flow into the second space (1114b), and this liquid refrigerant may flow into the second radial bearing (148) connected to the second space (1114b). Through this, the liquid refrigerant, which is the working fluid, may support the second radial bearing (148) to secure bearing force for the end of the second compression section (160) of the rotary shaft (130) and, at the same time, cool the second radial bearing (148) and the rotary shaft (130) facing it.

[0095] The present embodiment relates to a double-ended turbo compressor in which impellers (151, 161) are respectively coupled to both sides of a rotating shaft (130), and the impellers (151, 161) include first and second impellers (151, 161) respectively coupled to both sides of the rotating shaft (130). In addition, the shrouds (1122, 1132) may include first and second shrouds (1122, 1132) which are respectively arranged to face the first and second impellers (151, 161) and have compression paths (161a) through which refrigerant flows between the first and second impellers (151, 161), respectively.

[0096] For example, the shroud (1122, 1132) may be a configuration provided in the impeller housing (112, 113), as described below. The impeller housing (112, 113) may include a first impeller housing (112) that accommodates a first impeller (151) and a second impeller housing (113) that accommodates a second impeller (161).

[0097] Referring to FIG. 4, the first impeller housing (112) may include a first suction port (1121), a first shroud (1122), a first diffuser (1123), a first volute (1124), and a first discharge port (1125).

[0098] The first suction port (1121) may be formed in a direction penetrating both axial side surfaces from the center of the first impeller housing (112). For example, the first suction port (1121) may be opened at the front surface (first side) of the first impeller housing (112) and extend in the axial direction. The first suction port (1121) may be formed in a truncated cone shape in which the inlet end to which the refrigerant suction pipe (115) is connected is wide and the outlet end to which the first shroud (1122) is connected is narrow. Accordingly, the flow rate and velocity of the refrigerant sucked through the first suction port (1121) can be increased.

[0099] The first shroud (1122) extends from the outlet end of the first suction port (1121) toward the outer surface of the first impeller (151), and the first impeller (151) can be rotatably inserted into the inside of the first shroud (1122). Accordingly, the first shroud (1122) can be understood to have a first impeller receiving portion on the inner surface, and the inner surface of the first shroud (1122) on which the first impeller receiving portion is provided can be formed to be curved along the shape of the outer surface of the first impeller (151).

[0100] A compression path (161a) through which compressed refrigerant flows may be provided between the inner surface of the first shroud (1122) and the outer surface of the first impeller (151).

[0101] Unlike the second shroud (1132) described later, the first shroud (1122) is shown as an example of being formed integrally with the first impeller housing (112).

[0102] The second shroud (1132) is formed to be able to move relative to the second impeller housing (113), and the configuration of the second shroud (1132) will be described later.

[0103] The first diffuser (1123) may extend from the downstream end of the first shroud (1122). For example, the first diffuser (1123) may be formed as a space between the first side (143a) of the first bearing shell (143) facing the first side (1324a) of the thrust runner (1324) to be described later and the second side (112a) of the first impeller housing (112) facing it.

[0104] The first volute (1124) may be formed by being connected to the downstream side of the first diffuser (1123). For example, the first volute (1124) may be formed by being recessed in the axial rear surface of the first impeller housing (112). The first volute (1124) may be formed in a ring shape to surround the outer circumference of the first diffuser (1123), and may be formed such that the cross-sectional area gradually increases toward the first discharge port (1125) to be described later.

[0105] The first discharge port (1125) may be formed by penetrating the outer surface of the first impeller housing (112) at the center of the circumference of the first volute (1124). Accordingly, the inlet end of the first discharge port (1125) may be connected to the first volute (1124), while the outlet end may be connected to the second suction port (1131) of the second impeller housing (113) via a refrigerant connection pipe (116). The refrigerant connection pipe (116) may include a first connection pipe (1161) connected to the outlet end of the first discharge port (1125), and a second connection pipe (1162) connected between the first connection pipe (1161) and the second suction port (1131) of the second impeller housing (113), as illustrated in FIGS. 2 and 3 .

[0106] Referring to FIGS. 3 and 4, the second impeller housing (113) may be formed to be almost symmetrical with the first impeller housing (112) with the electric motor (120) as the center. For example, the second impeller housing (113) according to the present embodiment may include a second suction port (1131), a second shroud (1132), a second diffuser (1133), a second volute (1134), and a second discharge port (1135). The second suction port (1131) may be formed in approximately the same manner as the first suction port (1121), the second shroud (1132) may be formed in approximately the same manner as the first shroud (1122), the second diffuser (1133) may be formed in approximately the same manner as the first diffuser (1123), the second volute (1134) may be formed in approximately the same manner as the first volute (1124), and the second outlet (1135) may be formed in approximately the same manner as the first outlet (1125). The description of the second impeller housing (113) is replaced with the description of the first impeller housing (112).

[0107] However, referring to FIG. 4, unlike the first suction port (1121) described above, the second suction port (1131) may be formed such that the inlet end and the outlet end to which the second shroud (1132) is connected are formed in a shape that is almost parallel.

[0108] Additionally, the housing (110) is provided with a bypass passage (1137) that allows the refrigerant passing through the compression passage (161a) provided between the second impeller (161) and the second shroud (1132) to flow bypassing.

[0109] Referring to FIGS. 4 and 5, an example is shown in which a bypass passage (1137) is provided in the second impeller housing (113).

[0110] The bypass path (1137) can be understood as a path through which the discharged pressure of the second impeller (161) is reintroduced to pressurize the rear surface of the second shroud (1132).

[0111] The bypass path (1137) can be formed in a shape that is bent at least twice.

[0112] The bypass (1137) may include the first to third bypasses (1137a, 1137b, 1137c).

[0113] The first bypass path (1137a) may be provided in parallel with the rotation shaft (130) in the housing (110) on one side where the refrigerant is discharged from the second impeller (161).

[0114] The second bypass passage (1137b) is formed parallel to the first bypass passage (1137a) and may be connected to one side of the second shroud (1132). For example, the second bypass passage (1137b) may be connected to one side of the second shroud (1132) through a pressurized space (1132a) described below.

[0115] The third bypass (1137c) may be provided between the first bypass (1137a) and the second bypass (1137b).

[0116] As the first to third bypass passages (1137a, 1137b, 1137c) are provided in the housing (110), the refrigerant compressed by passing through the impeller (151, 161) passes through the first to third bypass passages (1137a, 1137b, 1137c) and can pressurize the second shroud (1132). Accordingly, the gap between the impeller (151, 161) and the shroud (1122, 1132) can be adjusted.

[0117] The first to third bypass passages (1137a, 1137b, 1137c) may be provided, for example, in the second shroud support section (1132c).

[0118] The housing (110) may include a second shroud support portion (1132c) that supports the second shroud (1132) so as to be relatively movable and has a guide surface portion (1132e) on one side. For example, the second impeller housing (113) may include a second shroud support portion (1132c).

[0119] The second shroud support member (1132c) can support the second shroud (1132) so that it can move relative to the second shroud. The second shroud support member (1132c) can have a guide surface member (1132e) on one side.

[0120] The guide surface portion (1132e) can be arranged parallel to one side of the second shroud (1132) so as to enable the second shroud (1132) to move in the axial direction. One side of the second shroud (1132) can be parallel to the guide surface portion (1132e), so that the second shroud (1132) can be guided and moved in the axial direction parallel to the guide surface portion (1132e).

[0121] A guide support member (1132f) may be provided between the guide surface (1132e) of the second shroud support member (1132c) and the second shroud (1132) to guide the axial movement of the second shroud (1132). The guide support member (1132f) may be, for example, an LM guide (Linear Motion Guide). However, it is not necessarily limited thereto, and the guide support member (1132f) may be any other configuration, such as an axial support bearing or a sealed support bearing, as long as it is a member capable of supporting the second shroud (1132) to guide the axial movement.

[0122] In this way, since the housing (110) is provided with a bypass passage (1137), the pressure discharged from the second impeller (161) can be reused, and thus the gap (C2) between the second impeller (161) and the second shroud (1132) can be adjusted according to the operating conditions of the turbo compressor.

[0123] As the turbo compressor rotates at a high speed, the discharge pressure from the first compression section is provided to the second compression section, and the gap between the first impeller (151) and the first impeller housing (112) in the first compression section decreases due to the thrust from the second compression section pushing the first compression section, and the gap between the second impeller (161) and the second impeller housing (113) in the second compression section increases, which is a problem. In order to supplement this problem, the gas force pushing the first-stage shroud (1122, 1132) must also increase in proportion to the rotation speed. Since the discharge pressure of the second-stage compression section also increases as the rotation speed increases, the gap can be simply adjusted without an additional device by pushing the second-stage shroud (1122, 1132) with the discharge pressure of the second-stage compression section.

[0124] The housing (110) may be provided with a pressurized space (1132a). The pressurized space (1132a) may be connected to a bypass passage (1137), so that the refrigerant passing through the compression passage (161a) passes through the bypass passage (1137) and is then received in the pressurized space (1132a) to pressurize the second shroud (1132).

[0125] As shown in FIGS. 4 and 5, a pressurized space (1132a) may be provided in the second impeller housing (113).

[0126] An elastic member (1132b) may be installed in the pressurized space (1132a). The elastic member (1132b) provides elastic force between the housing (110) and the second shroud (1132).

[0127] The elastic member (1132b) may be, for example, a spring.

[0128] The elastic member (1132b) can be connected to one side and the other side of the pressurized space (1132a), respectively.

[0129] One side of the pressurized space (1132a) may be defined by one side of the second shroud (1132), and the other side of the pressurized space (1132a) may be defined in the housing (110). The other side of the pressurized space (1132a) may be, more specifically, the second shroud support wall (1132d) of the second impeller housing (113). The second shroud support wall (1132d) may be provided with a guide end that is provided in a direction intersecting the second shroud support wall (1132d) and supports the second shroud (1132) and guides its axial movement. The guide end portion is spaced apart from the guide surface portion (1132e) of the second shroud support portion (1132c) and is arranged parallel to the guide surface portion (1132e) of the second shroud support portion (1132c), thereby guiding the axial movement of the second shroud (1132) from one side other than the guide surface portion (1132e). The guide end portion guides one end of the second shroud (1132) from one side. In addition, the other side of the guide end portion may be provided with a second suction port (1131).

[0130] Accordingly, the elastic member (1132b) provides elasticity between one side of the second shroud (1132) and the second shroud support wall (1132d) forming the other side of the pressurized space (1132a). By the elastic member (1132b), interference between the second shroud (1132) and the second impeller (161), which may occur when the refrigerant passing through the compression path (161a) passes through the bypass path (1137) and then pressurizes the second shroud (1132), can be prevented.

[0131] To explain in more detail, when the compressor rotates at high speed, the second discharge pressure discharged from the second impeller (161) increases, and the gas force pushing toward the second shroud (1132) increases. However, there is a concern that interference between the second impeller (161) and the second shroud (1132) may occur due to the instantaneous discharge pressure fluctuation. The reduced gap can be restored by pulling the second shroud (1132) by the elastic member (1132b) installed on the second shroud (1132).

[0132] Meanwhile, it is preferable that the elastic coefficient of the elastic member (1132b) be determined so that the elastic member (1132b) can prevent interference between the impeller (151, 161) and the shroud (1122, 1132) due to fluctuations in gas force.

[0133] If the second-stage discharge pressure is too great compared to the elastic force of the elastic member (1132b), the gap may become narrow and interference may occur. On the other hand, if the second-stage discharge pressure is small compared to the spring force, the gap cannot be adjusted.

[0134] Therefore, it is desirable that the elastic force of the elastic member (1132b) have an elastic coefficient that is neither too small nor too large compared to the two-stage discharge pressure.

[0135] In Fig. 6, a graph is shown for the optimal range of the spring constant K of the elastic member (1132b).

[0136] Fg may be a force that presses the shroud (1122, 1132) by the elastic force of the elastic member (1132b), i.e., an elastic force. If Fg is greater than a predetermined range value, there is a risk of interference between the shroud (1122, 1132) and the housing (110).

[0137] Conversely, if Fg becomes smaller than the predetermined range value, the gap between the shroud (1122, 1132) and the housing (110) becomes larger, making it impossible to adjust or control the gap.

[0138] Therefore, the discharge pressure in the two-stage compression unit must be used so as to use the optimal range of the spring constant K of the elastic member (1132b).

[0139] If the discharge pressure is too great compared to the elastic support capacity of the elastic member (1132b), the gap may become narrow and interference may occur, and if the discharge pressure is too small compared to the elastic support capacity of the elastic member (1132b), gap adjustment or gap control is not possible.

[0140] The gas discharged from the second impeller (161) increases in static pressure as it passes through the second diffuser (1133).

[0141] Figure 7 is a graph showing the relationship between the static pressure position and the discharge pressure.

[0142] The discharged gas is branched by selecting a position of pressure that matches the spring constant k of the elastic member (1132b) on the graph.

[0143] It is preferable that the bypass passage (1137) be provided between the outlet of the second impeller (161) and the inlet of the second volute (1134).

[0144] By this structure, the gap can be adjusted at all operating points of the turbo compressor by using the optimal discharge pressure that is not completely diffused, and interference between the impeller (151, 161) and the shroud (1122, 1132) is prevented.

[0145] The gap in the first compression section can be adjusted by the combined force of the discharge pressure and the elastic support force of the elastic member (1132b).

[0146] When the turbo compressor is operated at low speed, the Fs value becomes larger than the Fg value, and the gap between the second impeller (161) and the shroud (1132) is adjusted to become larger.

[0147] When the turbo compressor is operated at high speed, the Fg value becomes larger than the Fs value, and the gap between the second impeller (161) and the shroud (1132) is adjusted to become smaller.

[0148] The pressurized space (1132a) may be formed in the circumferential direction on one side of the second shroud (1132). For example, the pressurized space (1132a) may be provided in the circumferential direction at the second shroud support member (1132c). In the present embodiment, the second shroud (1132) and the second impeller (161) may have a portion extending in the circumferential direction. The second shroud support member (1132c), like the second shroud (1132), may also have a portion extending in the circumferential direction, and the pressurized space (1132a) may be provided in the circumferential direction at the second shroud support member (1132c).

[0149] The pressurized space (1132a) may be a space capable of receiving refrigerant that has passed through the bypass passage (1137). In addition, the pressurized space (1132a) may receive an elastic member (1132b). The pressurized space (1132a) may be formed as a space extending in the circumferential direction. The pressurized space (1132a) may receive refrigerant to pressurize the second shroud (1132), and it is preferable to have a width and depth determined so that the elastic member (1132b) can be installed.

[0150] The elastic member (1132b) may be provided in at least two pieces. The at least two elastic members (1132b) may be arranged to be spaced apart from each other in the circumferential direction. It is preferable that the at least two elastic members (1132b) are spaced apart from each other at equal intervals.

[0151] Since a plurality of elastic members (1132b) are provided and spaced at equal intervals in the circumferential direction, interference between the second shroud (1132) and the second impeller (161), which may occur when the refrigerant passing through the compression path (161a) passes through the bypass path (1137) and pressurizes the second shroud (1132), can be prevented more reliably.

[0152] According to an example related to the present invention, the gap between the second shroud (1132) and the second impeller (161) can be adjusted to correspond to the gap between the first shroud (1122) and the first impeller (151).

[0153] In a turbo compressor, the gap between the impeller (151, 161) and the shroud (1122, 1132) is determined by considering various tolerances such as machining tolerance, assembly tolerance, and bearing tolerance. These tolerances are absolute values, and even when the turbo compressor is reduced in size from large to small, the tolerances have almost the same value.

[0154] Therefore, as compressors become smaller, the overall clearance increases relative to the flow rate, which in turn increases the gap leakage relative to the overall flow rate. In other words, the need for gap-reducing technology in small turbocompressors is relatively greater.

[0155] In the two-stage turbo compressor of the present invention, thrust is generated in the direction of the rotation shaft (130) due to the pressure difference generated in the first-stage compression section and the second-stage compression section, and in the first-stage compression section, the gap between the first impeller (151) and the first shroud (1122) is made large. In particular, as the compressed refrigerant discharged from the first-stage compression section flows into the second-stage compression section, thrust is generated in the second-stage compression section in the direction of the first-stage compression section, so that the gap between the first impeller (151) and the first shroud (1122) is reduced, and the gap between the second impeller (161) and the second shroud (1132) is increased.

[0156] When the rotating shaft (130) of the turbo compressor rotates, the impeller (151, 161) blades are deformed by the reaction force of the force that the impeller (151, 161) blades push against the gas. The gap increases as the blades lie down due to the deformation of the impeller (151, 161) blades. Since the reaction force of the gas acting on the impeller (151, 161) blades increases as the rotational speed increases, the gap due to the deformation of the impeller (151, 161) also increases during high-speed operation. Therefore, a technology that can control the gap according to the rotational speed of the turbo compressor can increase the efficiency of the compressor at a high-speed operating point.

[0157] When the turbo compressor operates, the impeller (151, 161) rotates and pushes the gas, increasing the pressure. The high-pressure gas, whose pressure has increased as it passes through the impeller (151, 161), leaks through the gap between the impeller (151, 161) and the housing (110), thereby increasing the internal pressure of the housing (110) on the rear side of the impeller (151, 161). As a result, thrust of the shaft system is applied due to the pressure formed at the inlet, inside, and rear of the impeller (151, 161).

[0158] In the turbo compressor of this unit, a difference in pressure may occur between the first and second compression sections. Due to the pressure difference between the first and second compression sections, a difference in thrust between the first and second impellers (161) occurs, and the combined force of these two thrusts ultimately becomes the thrust applied to the shaft.

[0159] Since the pressure of the second-stage compression section is higher than that of the first-stage compression section, suction pressure or first-stage discharge pressure may be applied inside the housing (110) to reduce the thrust of the shaft, and a seal may be installed on the impeller (151, 161) to prevent leakage. In this case, the resultant force of the entire system moves in the first-stage direction, and when the operating speed increases and the pressure increases, the shaft system moves further in the first-stage direction, and the gap toward the second stage increases, resulting in a decrease in efficiency.

[0160] The present invention enables the gap between the two stages to be adjusted in order to resolve the problem of the gap between the two stages increasing during operation of a turbo compressor. High-pressure gas force is applied to the shrouds (1122, 1132) of the second stage to bring them closer to the impellers (151, 161). To this end, a space is created between the second shroud (1132) and the housing (110), and high-pressure gas is supplied to this space.

[0161] The high-pressure gas supplied to the second shroud (1132) uses a portion of the discharge gas of the second-stage compression section of the turbocompressor. By using the discharge pressure of the second-stage compression section, the gap can be adjusted according to the operating conditions of the turbocompressor. As the turbocompressor rotates at a high speed, the problem of the gap of the first stage decreasing may occur, and in order to compensate for this problem, the gas force pushing the first-stage shroud (1122, 1132) must also increase in proportion to the rotation speed. Since the discharge pressure of the second-stage compression section also increases as the rotation speed increases, the gap can be simply adjusted without an additional device by pushing the second shroud (1132) with the discharge pressure of the second-stage compression section.

[0162] Therefore, since the gap in the first compression section does not increase, the gap leakage of the turbo compressor can be reduced, thereby increasing efficiency.

[0163] For example, as described above, in the present invention, the gap between the second impeller (161) and the second shroud (1132) can be adjusted by pressurizing the second shroud (1132) through the bypass passage (1137) in the second impeller housing (113).

[0164] In particular, the compressed refrigerant that has passed through the bypass passage (1137) is received in the pressurized space (1132a) and can pressurize the second shroud (1132) more stably.

[0165] In addition, an elastic member (1132b) is installed in the pressurized space (1132a), so that interference between the second shroud (1132) and the second impeller (161) that may occur when the high-pressure refrigerant pressurizes the second shroud (1132) can be prevented.

[0166] Again, referring to FIG. 4, the electric motor (120) according to the present embodiment may include a stator (121) and a rotor (122).

[0167] The stator (121) may include a stator core (1211) and a stator coil (1212). The stator core (1211) is press-fitted and fixed to the motor housing (111), and the stator coil (1212) may be wound around the stator core (1211). Accordingly, a circumferential gap is generated between the two stator coils (1212), and this circumferential gap becomes a refrigerant passage that connects the first space (1114a) and the second space (1114b) of the motor housing (111) to each other.

[0168] The rotor (122) can be rotatably arranged inside the stator (121) and spaced apart from the inner surface of the stator (121). The rotor (122) includes a rotor core (1221) and a permanent magnet (1222), but the rotor core (1221) can be coupled to the rotation shaft (130) or omitted. When the rotor core (1221) is omitted, the permanent magnet (1222) can be attached to the outer surface of the rotation shaft (130) or mounted inside the rotation shaft (130). This embodiment illustrates an example in which the permanent magnet (1222) is inserted into the interior of the rotation shaft (130) so that a portion of the rotation shaft (130) forms the rotor core (1221).

[0169] Referring to FIG. 4, the rotation shaft (130) according to the present embodiment may include a drive shaft portion (131), a first impeller shaft portion (132), and a second impeller shaft portion (133).

[0170] The drive shaft portion (131) may be formed in a cylindrical shape and may be rotatably installed inside the stator (121). For example, the length of the drive shaft portion (131) may be formed to be longer than or equal to the axial length of the stator (121), and the axial center of the drive shaft portion (131) may be coupled to be positioned radially on the same line as the axial center of the stator (121).

[0171] The first impeller shaft portion (132) may be extended or assembled as a single body from one end of the drive shaft portion (131), and the second impeller shaft portion (133) may be extended or assembled as a single body from one end of the drive shaft portion (131). In this embodiment, an example is shown in which the first impeller shaft portion (132) and the second impeller shaft portion (133) are extended as a single body from both ends of the drive shaft portion (131).

[0172] A thrust runner (1324) that is axially supported by a first thrust bearing (146) and a second thrust bearing (147) to be described later may be formed on the first impeller shaft portion (1322). For example, the thrust runner (1324) may be formed in a disk shape by extending radially from the outer circumferential surface of the first bearing surface portion (1322).

[0173] Referring to FIG. 4, the thrust runner (1324) may be provided between the first bearing shell (143) and the bearing support member (1115) and may be axially supported. In other words, the thrust runner (1324) may form a movable side support member, and the first bearing shell (143) and the bearing support member (1115) may each form a fixed side support member. Accordingly, the rotation shaft (130) may be axially supported on both sides together with the first impeller (151) and the second impeller (161) coupled to both ends of the rotation shaft (130).

[0174] The thrust runner (1324) may be formed so that its outer circumference is spaced apart from the inner circumference of the first space (1114a). The outer diameter of the thrust runner (1324) may be formed smaller than the inner diameter of the first space (1114a). Although not shown in the drawing, coolant may be supplied to the first thrust bearing (146) and the second thrust bearing (147) through a coolant supply unit (not shown), and in this case, the coolant moves toward the driving motor (120).

[0175] As illustrated in FIG. 4, the first thrust bearing (146) may be provided on a first side (not shown) of the thrust runner (1324) facing the first impeller (151). The second thrust bearing (147) may be provided on a second side (not shown) of the thrust runner (1324) facing the electric motor (120). In this case, since both the first thrust bearing (146) and the second thrust bearing (147) are installed on the rotation shaft (130), the installation and assembly of the first thrust bearing (146) and the second thrust bearing (147) may be easy.

[0176] The second impeller shaft portion (133) may be inserted and fixed into the second compression portion (160) side end (hereinafter referred to as the second end) of the drive shaft portion (131). For example, the second impeller shaft portion (133) may be welded and joined in a press-fit state to the second end of the drive shaft portion (131), similar to the first impeller shaft portion (132).

[0177] The second impeller shaft portion (133) is formed symmetrically with respect to the first impeller shaft portion (132) and the drive shaft portion (131), but since the second bearing portion (142) is not provided with a thrust bearing, a thrust runner (not shown) may be excluded. However, in some cases, the second bearing portion (142) may also be provided with a thrust bearing, and the second impeller shaft portion (133) may be provided with a thrust runner (not shown).

[0178] Referring to FIGS. 4 and 5, the first compression unit (150) according to the present embodiment may include a first impeller (151), a first diffuser (1123), and a first volute (1124). However, among the components forming the first compression unit (150), the first diffuser (1123) and the first volute (1124) are as described above with respect to the first impeller housing (112). That is, the first diffuser (1123) is formed between the first impeller housing (112) and the first bearing shell (143), and the first volute (1124) may be formed in the first impeller housing (112).

[0179] As described above, the first impeller (151) forms a first compression unit (150), which is functionally a single-stage compression unit, together with the first diffuser (1123) and the first volute (1124). Accordingly, the suction side of the first impeller (151) can be connected to the refrigerant suction pipe (115), and the discharge side of the first impeller (151) can be connected to the suction side of the second impeller (161), which forms part of the two-stage compression unit (second compression unit (160)), through the refrigerant connection pipe (116).

[0180] Referring to FIG. 4, the second compression unit (160) according to the present embodiment may include a second impeller (161), a second diffuser (1133), and a second volute (1134). However, among the components forming the second compression unit (160), the second diffuser (1133) and the second volute (1134) are as described above with respect to the second impeller housing (113). That is, the second diffuser (1133) is formed between the second impeller housing (113) and the second bearing shell (144), and the second volute (1134) may be formed in the second impeller housing (113).

[0181] As previously described, the second impeller (161) forms a functional two-stage compression unit together with the second diffuser (1133) and the second volute (1134). Accordingly, the suction side of the second impeller (161) can be connected to the discharge side of the first impeller (151) via a refrigerant connection pipe (116), and the discharge side of the second impeller (161) can be connected to the inlet side of the condenser (20) via a refrigerant discharge pipe (117).

[0182] The overall shape of the second impeller (161) may be formed to be almost identical to that of the first impeller (151). However, the diameter of the second impeller (161) may be formed to be smaller than that of the first impeller (151). The shape of the second impeller (161) is replaced with the description of the first impeller (151).

[0183] The turbo compressor according to the above embodiment operates as follows.

[0184] That is, when power is applied to the electric motor (120), rotational force is generated by the induced current between the stator (121) and the rotor (122), and the rotational force causes the rotational shaft (130) to rotate together with the rotor (122).

[0185] Then, the rotational power of the electric motor (120) is transmitted to the first impeller (151) and the second impeller (161) by the rotation shaft (130), and the first impeller (151) and the second impeller (161) rotate simultaneously in the compression path (161a) formed between the first and second shrouds (1122, 1132), respectively.

[0186] Then, the refrigerant that has passed through the evaporator (40) of the refrigeration cycle device flows into the space where the first impeller (151) is accommodated through the refrigerant suction pipe (115) and the first suction port (1121), and the refrigerant moves while rotating along the first impeller (151), increasing the static pressure and simultaneously passing through the first diffuser (1123) with centrifugal force.

[0187] Then, the refrigerant passing through the first diffuser (1123) has kinetic energy that leads to an increase in pressure head by centrifugal force in the first diffuser (1123), and the centrifugally compressed high-temperature, high-pressure refrigerant is collected in the first volute (1124) and discharged from the first compression unit (150) through the first discharge port (1125).

[0188] Then, the refrigerant discharged from the first compression unit (150) is guided to the second suction port (1131) of the second impeller housing (113) forming the second compression unit (160) through the refrigerant connection pipe (116), and the refrigerant moves while rotating along the second impeller (161), and the static pressure increases again while passing through the second diffuser (1133) with centrifugal force at the same time.

[0189] Then, the refrigerant passing through the second diffuser (1133) is compressed to the desired pressure by centrifugal force, and this two-stage compressed high-temperature, high-pressure refrigerant is collected in the second volute (1134) and discharged to the condenser (20) through the second discharge port (1135) and the refrigerant discharge pipe (117), repeating a series of processes.

[0190] Meanwhile, some of the refrigerant passing through the second diffuser (1133) flows into the pressurized passage through the first to third bypass passages (1137a, 1137b, 1137c), pressurizes the rear surface of the second shroud (1132), and adjusts the gap between the second shroud (1132) and the second impeller (161).

[0191] The elastic member (1132b) within the pressurized euro provides elasticity to the second shroud (1132) to prevent interference between the second shroud (1132) and the second impeller (161).

[0192] Hereinafter, another embodiment of the turbo compressor of the present invention will be described with reference to FIGS. 9 to 11.

[0193] The difference from the previous embodiment is that the first stage compression unit and the second stage compression unit are not connected to each other by a separate refrigerant connection pipe (116) provided on the outside of the housing (110). That is, the difference is that the first to third flow paths (1125d, 1115d, 1136a) are provided on the inside of the housing (110).

[0194] On one side of the first impeller housing (112), a first flow path (1125d) is provided to allow the discharged refrigerant discharged from the first impeller (151) to flow.

[0195] The motor housing (110) is provided with a second passage (1115d) that is connected to the first passage (1125d) and provides discharged refrigerant to the second impeller housing (113).

[0196] On one side of the second impeller housing (113), a third flow path (1136a) is provided that is connected to the second flow path (1115d) and enables the discharged refrigerant to be supplied to the suction port of the second impeller (161).

[0197] For example, in the present invention, the first flow path (1125d) may be provided inside the first impeller housing (112), the second flow path (1115d) may be provided inside the motor housing (110), and the third flow path (1136a) may be provided inside the second impeller housing (113).

[0198] That is, in the present invention, after the compressed refrigerant is discharged from the first impeller (151), the refrigerant flow path provided to the second impeller (161) may be provided not on the outside of the housing (110) forming the turbo compressor (10) of the present invention, but on the inside of the housing (110).

[0199] The turbo compressor (10) of the present invention does not use a separate pipe, compared to a structure using a conventional separate pipe and a flow path provided on the outside of the housing (110), and in particular, the flow path is provided on the inside of the housing (110).

[0200] Accordingly, the overall size of the turbo compressor (10) can be reduced, so that the packaging area can be reduced compared to the existing turbo compressor (10).

[0201] The first euro-accommodating protrusion (1125) is provided on the upper side (112b) of the first impeller housing (112) where the first suction port (1121) is illustrated. The side (112b) may be the left side.

[0202] For example, the first flow passage accommodating portion (1125) may be formed integrally with the first impeller housing (112). Since the first flow passage accommodating portion (1125) is formed integrally with the first impeller housing (112), compared to a structure in which a separate pipe is installed in the existing first impeller housing (112), installation of a gasket and bolts is not required, thereby reducing manufacturing and maintenance costs.

[0203] The second impeller housing (113) may be provided with a third flow path receiving projection (1136) that protrudes from one surface of the exterior and has a third flow path (1136a) provided therein.

[0204] The third flow passage receiving protrusion (1136) is provided on one side (113b) of the second suction port (1131) of the second impeller housing (113) shown in FIGS. 9 and 10. The outlet end of the third flow passage receiving protrusion (1136) can be connected to the inlet end of the second suction port (1131) of the second impeller housing (113), and the outlet end of the third flow passage receiving protrusion (1136) can be coupled to the center of the second impeller housing (113).

[0205] For example, the third flow passage accommodating portion (1136) may be formed integrally with the second impeller housing (113). Since the third flow passage accommodating portion (1136) is formed integrally with the second impeller housing (113), compared to a structure in which a separate pipe is installed in the existing second impeller housing (113), installation of a gasket and bolts is not required, thereby reducing manufacturing and maintenance costs.

[0206] The motor housing (110) may be provided with a second flow path receiving projection (1113) that protrudes from the outer periphery and has a second flow path (1115d) provided therein.

[0207] For example, the second flow passage accommodating portion (1113) may be formed integrally with the motor housing (110). Since the second flow passage accommodating portion (1113) is formed integrally with the motor housing (110), the size of the motor housing (110) in the lateral direction can be reduced compared to a structure in which a separate pipe is arranged on the side of the existing motor housing (110), thereby enabling the packaging area to be reduced compared to the existing turbo compressor (10).

[0208] Referring to FIGS. 9 and 10, an example is shown in which a first flow passage accommodating protrusion (1125) is provided on one surface of a first impeller housing (112) visible in the drawings. The first flow passage accommodating protrusion (1125) is spaced apart from the center of the first impeller housing (112) in which the first suction port (1121) is provided by a predetermined distance. This is because the refrigerant that is introduced into the first impeller (151) near the center of the first impeller housing (112) and compressed flows out through the first flow passage accommodating protrusion (1125) from the side of the first impeller housing (112).

[0209] On the other hand, one end of the third flow passage receiving member (1136) on the outlet side is connected to the center of the second impeller housing (113). This is because the refrigerant compressed in the first impeller (151) flows through the flow path inside the third flow passage receiving member (1136) and flows into the second impeller (161) from the center of the second impeller housing (113).

[0210] In addition, as illustrated in FIGS. 9 and 10, the motor housing (110) is provided with a second flow passage protrusion (1113) between the first flow passage protrusion (1125) and the third flow passage protrusion (1136). The second flow passage protrusion (1113) is connected to the first flow passage protrusion (1125) and the third flow passage protrusion (1136), respectively, so that the refrigerant compressed in the first impeller (151) and passing through the first flow passage protrusion (1125) can be supplied to the third flow passage protrusion (1136).

[0211] The ends of the first flow passage receiving portion (1125) and the third flow passage receiving portion (1136) may be arranged parallel to each other. The ends of the first flow passage receiving portion (1125) and the third flow passage receiving portion (1136) may each be provided with a first flange portion (1125c, 1136e).

[0212] At both ends of the second flow passage accommodating portion (1113), a second flange portion (1113c) may be provided so as to be sealedly connected to the first flange portions (1125c, 1136e) provided at the ends of the first flow passage accommodating portion (1125) and the third flow passage accommodating portion (1136), respectively.

[0213] The first flange portion (1125c) may be formed to protrude laterally, i.e., in the radial direction of the flow path, from the end of the first flow path receiving portion (1125). Accordingly, it may have a larger diameter than the first flow path receiving portion (1125).

[0214] The second flange portion (1113c), like the first flange portion (1125c, 1136e), may be formed to protrude laterally, i.e., in the radial direction of the flow path, from the end of the second flow path-accommodating protrusion (1113). The second flange portion (1113c) may have a larger diameter than the second flow path-accommodating protrusion (1113).

[0215] By means of the first and second flange portions (1125c, 1136e, 1113c), the assembly between the first to third flow passage accommodating portions (1125, 1113, 1136) can be improved. In addition, a flow path can be provided through which the refrigerant discharged from the first impeller (151) can flow toward the second impeller (161) without causing refrigerant leakage between the first to third flow passage accommodating portions (1125, 1113, 1136).

[0216] For example, the first flange portion (1125c, 1136e) and the second flange portion (1113c) can be connected to each other by bolting. To this end, the first flange portion (1125c, 1136e) and the second flange portion (1113c) can be provided with a plurality of holes formed to be in communication with each other. Bolts are connected to the plurality of holes of the first flange portion (1125c, 1136e) and the second flange portion (1113c), so that the first flange portion (1125c, 1136e) and the second flange portion (1113c) can be connected to each other.

[0217] Referring to FIG. 10, the first euro-accommodating protrusion (1125) may include a first portion (1125a) and a second portion (1125b).

[0218] The first portion (1125a) can extend in a direction intersecting one surface of the exterior of the first impeller housing (112) with one surface of the exterior of the first impeller housing (112).

[0219] The second part (1125b) may be formed into a curved surface, extending from the end of the first part (1125a).

[0220] As described above in the description of the previous embodiment, some of the refrigerant passing through the second diffuser (1133) flows into the inside of the pressurized passage through the first to third bypass passages (1137a, 1137b, 1137c), pressurizes the rear surface of the second shroud (1132), and the feature of adjusting the gap between the second shroud (1132) and the second impeller (161) can also be applied to the embodiments of FIGS. 10 and 11.

[0221] Likewise in the embodiments of FIGS. 10 and 11, the elastic member (1132b) within the pressurized passage provides elastic force to the second shroud (1132) to prevent interference between the second shroud (1132) and the second impeller (161).

[0222] The turbo compressor (10) described above is not limited to the configuration and method of the embodiments described above, and the embodiments may be configured by selectively combining all or part of each embodiment so that various modifications can be made.

[0223] It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit and essential characteristics thereof. Therefore, the above detailed description should not be construed in any way as limiting but rather as illustrative. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents of the present invention are intended to be included within the scope of the present invention.

[0224] The present invention can be used in a turbocompressor capable of adjusting the gap between a shroud and an impeller according to the operating speed of the turbocompressor.

Claims

1. Housing forming the exterior; A rotary shaft rotatably installed inside the housing; An impeller that rotates and is coupled to the above rotating shaft; A shroud provided on the inner periphery of the housing, accommodating the impeller so that the impeller can be rotatably installed, and having a compression path through which the compressed refrigerant flows between the shroud and the impeller; The above impeller includes first and second impellers respectively coupled to both sides of the rotating shaft, The shroud includes first and second shrouds that accommodate the first and second impellers, respectively, A turbo compressor in which the housing is provided with a bypass passage that allows the refrigerant passing through the compression passage to bypass, and the bypass passage is connected to one side of the second shroud.

2. In paragraph 1, A turbo compressor having a pressurized space in the housing that is connected to the compression path and enables pressurization of the second shroud.

3. In paragraph 2, A turbo compressor in which an elastic member is installed in the pressurized space to provide elastic force between the housing and the second shroud.

4. In paragraph 3, A turbo compressor in which the elastic member is arranged parallel to the axial direction in which the rotation axis extends, and both ends are fixed between one surface of the second shroud and one surface of the housing.

5. In paragraph 3, A turbocompressor in which the pressurized space is formed in a circumferential direction on one side of the second shroud, the elastic members are provided in at least two numbers, and the at least two elastic members are arranged to be spaced apart from each other in the circumferential direction.

6. In paragraph 1, The above detour route is, A first bypass passage provided parallel to the rotation axis in one side of the housing through which the refrigerant is discharged from the second impeller; A second bypass passage formed parallel to the first bypass passage and connected to one side of the second shroud; and A turbo compressor including a third bypass passage provided between the first bypass passage and the second bypass passage.

7. In paragraph 6, The housing further comprises one side on which the impeller is provided to compress and increase the refrigerant discharged from the impeller, and a diffuser formed radially from the one side to the other side, The first bypass is a turbo compressor branched between one side of the housing where the impeller is provided and the other side of the diffuser.

8. In paragraph 1, One side of the second shroud is provided so that the second shroud is parallel to the axial direction in which the rotation axis extends, A turbo compressor having a guide surface portion connected to the first surface in parallel with the first surface so as to enable the second shroud to move in the axial direction in the housing.

9. In paragraph 8, A turbo compressor having a second shroud support portion that supports the second shroud so as to be relatively movable and has the guide surface portion on one side thereof.

10. In paragraph 8, A turbo compressor in which a guide support member is provided between the above guide surface and the second shroud to guide axial movement of the second shroud.

11. In paragraph 1, The housing includes a motor housing having a motor room, and first and second impeller housings that respectively accommodate the first and second impellers so as to be rotatable. A turbo compressor in which the second shroud is installed so as to be movable relative to the second impeller housing.

12. In paragraph 6, The above housing is provided with a pressurized space that is connected to the compression path and enables pressurization of the second shroud, A turbo compressor connected to the inside of the pressurized space through the second bypass passage.

13. In paragraph 1, The housing includes a motor housing having a motor room, and first and second impeller housings that respectively accommodate the first and second impellers so as to be rotatable. On one side of the first impeller housing, a first flow path is provided to allow the refrigerant compressed in the first impeller to flow. The above motor housing is provided with a second passage that is connected to the first passage and provides the compressed refrigerant to the second impeller housing. A turbo compressor having a third flow path on one side of the second impeller housing that is connected to the second flow path and enables the compressed refrigerant to be supplied to the suction port of the second impeller.

14. In paragraph 13, A turbo compressor in which the first impeller housing is provided with a first flow path receiving projection that protrudes from one surface of the exterior and has the first flow path provided therein.

15. In paragraph 14, The above first euro-receiving portion is, A first portion extending in a direction intersecting one surface of the exterior of the first impeller housing; and A turbocompressor comprising a second portion extending from an end of the first portion and formed into a curved surface.

16. In paragraph 14, A turbo compressor having a second flow path receiving projection formed protruding from the outer periphery of the above motor housing and having the second flow path provided therein.

17. In paragraph 16, A turbo compressor in which the second impeller housing is provided with a third flow path receiving projection formed protruding from one surface of the exterior and having the third flow path provided therein.

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