Supercharger and heat recovery system

Abstract

A housing of this supercharger includes an outer intake wall surface forming an outer surface of a gas intake flow passage in a cross section along the axial direction of the rotor. The outer intake wall surface has a first curved surface that curves so as to protrude toward one side of the rotor, and a second curved surface that curves so as to protrude toward the other side of the rotor. In the cross section along the axial direction of the rotor, the first curved surface has a first apex, which is the part of the first curved surface located furthest toward the one side of the rotor, and the second curved surface has a second apex, which is the part of the second curved surface located furthest toward the other side of the rotor. The second apex is located on the other side of the rotor with respect to the first vertex.

Description

Supercharger and Heat Recovery System

[0001] The present disclosure relates to a supercharger in which a turbine impeller and a compressor impeller are arranged back-to-back at one end of a rotor, and a heat recovery system including the supercharger.

[0002] Conventionally, a supercharger in which a turbine impeller and a compressor impeller are arranged back-to-back at one end of a rotor has been known (for example, Patent Documents 1 and 2).

[0003] Japanese Patent Application Laid-Open No. 2002-246058, Japanese Patent Application Laid-Open No. 2006-046337

[0004] The supercharger is preferably made compact.

[0005] An object of the present disclosure is to provide a compact supercharger and a heat recovery system.

[0006] A supercharger according to at least one embodiment of the present disclosure includes: a rotor; a motor including a first compressor impeller disposed on one side of the rotor; a turbine impeller disposed back-to-back with the first compressor impeller on the one side of the rotor relative to the first compressor impeller; a rotor disposed on the other side of the rotor relative to the first compressor impeller; and a stator disposed around the rotor; and a housing for housing at least the motor and the first compressor impeller, wherein an axial gas introduction passage extending outward from the stator and along the axial direction of the rotor is formed in the housing, and a gas intake passage for guiding the gas introduced by the axial gas introduction passage to the first compressor impeller, wherein the housing includes an outer intake wall surface forming the outer surface of the gas intake passage in a cross section along the axial direction of the rotor, and the outer intake wall surface is A first curved surface that curves so as to be convex toward one side of the rotor, and in the cross-section, the first curved surface has a first vertex that is located furthest toward the one side of the rotor on the first curved surface; and a second curved surface that is located downstream of the first curved surface in the gas flow direction and curves so as to be convex toward the other side of the rotor, and in the cross-section, the second curved surface has a second vertex that is located furthest toward the other side of the rotor on the second curved surface, wherein the second vertex is located on the other side of the rotor relative to the first vertex.

[0007] A heat recovery system according to at least one embodiment of the present disclosure is a heat recovery system comprising: a supercharger; and a heat recovery device configured to recover heat from compressed gas compressed by the first compressor impeller, wherein the supercharger is configured such that the gas from which the heat has been recovered by the heat recovery device flows into the turbine impeller as exhaust gas.

[0008] This disclosure provides a compact turbocharger and heat recovery system.

[0009] This is a schematic diagram of a heat recovery system according to one embodiment. This is a schematic diagram of a gas intake passage according to one embodiment. This is a schematic graph showing the relationship between the cross-sectional area of ​​the gas intake passage and the flow direction position. This is a schematic diagram of a turbine impeller according to one embodiment. This is a schematic diagram of the details of a supercharger according to one embodiment. This is a schematic diagram of the details of a heat recovery system (first embodiment). This is a schematic diagram of the details of a heat recovery system (second embodiment).

[0010] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described as embodiments or shown in the drawings are not intended to limit the scope of this disclosure, but are merely illustrative examples. For example, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only describe such arrangements strictly, but also represent states where there are tolerances or relative displacements of an angle or distance sufficient to achieve the same function. For example, expressions describing things being in an equal state such as "identical," "equal," and "homogeneous" should not only describe states where things are strictly equal, but also represent states where there are tolerances or differences sufficient to achieve the same function. For example, expressions describing shapes such as square or cylindrical should not only describe geometrically precise square or cylindrical shapes, but also shapes including concave and concave parts, chamfered parts, etc., to the extent that the same effect can be achieved. On the other hand, expressions such as "possessing," "including," or "having" a single component are not exclusive expressions that exclude the existence of other components. Furthermore, similar components may be denoted by the same symbol, and their explanations may be omitted.

[0011] <Overview of Heat Recovery System 1> Figure 1 is a schematic diagram of a heat recovery system 1 according to one embodiment of the present disclosure. The heat recovery system 1 comprises a supercharger 2 and a heat recovery device 3. The supercharger 2 performs a compressor function to generate compressed gas G1 and a turbine function to expand exhaust gas G3. Compressed gas G1 is supplied to the heat recovery device 3 via a supply line L1. The heat recovery device 3 is configured to recover heat from the compressed gas G1. More specifically, the heat recovery device 3 may use the heat contained in the compressed gas G1 to heat another object, or it may cool the compressed gas G1 by exchanging heat between the compressed gas G1 and another object (further details of the heat recovery device 3 will be described later). When heat is recovered from the compressed gas G1 in the heat recovery device 3, exhaust gas G3 is generated from the compressed gas G1. The exhaust gas G3 returns to the supercharger 2 via the discharge line L2 and expands in the supercharger 2.

[0012] The supercharger 2 comprises a rotor 5 and a first compressor impeller 10 and a turbine impeller 40, each positioned on one side of the rotor 5. Figure 1 schematically illustrates the configuration of the supercharger 2 on one side with respect to the axial center of the rotor 5. Any configuration may be adopted for the supercharger 2 on the other side of the rotor 5.

[0013] Hereafter, the axial direction of the rotor 5 will be abbreviated as "axial direction," and the circumferential and radial directions, relative to the axis 5c of the rotor 5, will be simply abbreviated as "circumferential direction" and "radial direction," respectively. "One side in the axial direction" is synonymous with "one side of the rotor 5," and "the other side in the axial direction" is synonymous with "the other side of the rotor 5." In this paper, "one side in the axial direction" and "the other side in the axial direction" will be abbreviated as "one side" and "the other side," respectively. Also, "inside in the radial direction" means the direction approaching the axis 5c of the rotor 5, and "outside in the radial direction" means the direction away from the axis 5c. In this paper, "inside in the radial direction" and "outside in the radial direction" will be written as "inner circumference side" and "outer circumference side," respectively.

[0014] <Overview of Supercharger 2> As shown in Figure 1, the supercharger 2 is equipped with a one-sided journal bearing B1 that supports the rotor 5. The first portion 51, which is the part of the rotor 5 that protrudes to one side in the axial direction from the one-sided journal bearing B1, is cantilevered by the one-sided journal bearing B1. The first compressor impeller 10 and the turbine impeller 40 are arranged back-to-back on the first portion 51, and the turbine impeller 40 is positioned to one side of the first compressor impeller 10. The supercharger 2 further comprises a first compressor housing 33 that houses the first compressor impeller 10 and a turbine housing 34 that houses the turbine impeller 40, and the first compressor housing 33 supports the one-sided journal bearing B1 mentioned above.

[0015] The first compressor housing 33 has a gas intake passage 80 for guiding supply gas to the first compressor impeller 10 and a first compressor-side passage 31 for compressed gas G1 to flow toward the supply line L1. The first compressor-side passage 31 includes a diffuser passage 31d. The turbine housing 34 has a turbine-side passage 38 into which exhaust gas G3 from the discharge line L2 flows, and an exhaust passage 32 through which the exhaust gas G3 that has passed through the turbine impeller 40 flows. The turbine-side passage 38 includes a turbine-side scroll passage 37 and a turbine outlet passage 36.

[0016] A first radially extending wall portion 70 is positioned between the first compressor-side flow path 31 and the turbine-side flow path 38, extending radially. The first radially extending wall portion 70 constitutes a part of the flow path wall surface of the first compressor-side flow path 31 and the turbine-side flow path 38. In Figure 1, the first radially extending wall portion 70 is configured separately from the first compressor housing 33 and the turbine housing 34, but the disclosure is not limited thereto.

[0017] The supercharger 2 further comprises a motor 60. The motor 60 includes a rotor 61, a stator 62, and a stator coil 63. The rotor 61 is positioned on the rotor 5 on the side opposite to the one-side journal bearing B1. The stator 62 is positioned around the rotor 61. The stator coil 63 is positioned on the stator 62.

[0018] The supercharger 2 further includes a motor housing 65 that houses the motor 60. The housing 8 has an axial gas introduction passage 67 that extends axially on the outer circumference of the stator 62, and a coolant flow passage 66 that extends circumferentially between the axial gas introduction passage 67 and the stator 62. The axial gas introduction passage 67 is configured to guide supply gas to the gas intake passage 80. Coolant is configured to flow through the coolant flow passage 66.

[0019] In a cross-section of the housing 8 along the axial direction, the motor housing 65 includes an outer introduction wall surface 68 that forms the radial outer surface of the axial gas introduction passage 67, and an inner introduction wall surface 69 that forms the radial inner surface of the axial gas introduction passage 67.

[0020] In the following description, the motor housing 65, the first housing 30, the first radially extending wall portion 70, and the turbine housing 34 may be collectively referred to as "housing 8".

[0021] The operation overview of the turbocharger 2 shown in Figure 1 is as follows: When the stator 62 is energized, the motor 60 rotates the rotor 5. The first compressor impeller 10, which rotates with the rotor 5, generates compressed gas G1 by compressing the supply gas introduced from the axial gas introduction passage 67 to the gas intake passage 80. The compressed gas G1 flows from the first compressor impeller 10 through the first compressor-side passage 31 to the supply line L1. The exhaust gas G3 discharged from the heat recovery device 3 flows into the turbine-side passage 38 via the discharge line L2. The exhaust gas G3 expands as it passes through the turbine impeller 40, and the turbine impeller 40 recovers rotational power from the exhaust gas G3. The exhaust gas G3 is discharged to the outside of the turbocharger 2 from the exhaust passage 32.

[0022] <Gas Intake Passageway 80> Figure 2 is an enlarged view of the gas intake passageway 80. The gas intake passageway 80 includes an outer intake wall surface 85 that forms the outer surface of the gas intake passageway 80 in a cross-section of the housing 8 along the axial direction of the rotor 5. The outer intake wall surface 85 has a first curved surface 81 and a second curved surface 82 that is positioned downstream of the first curved surface 81 in the flow direction of the supply gas.

[0023] The first curved surface 81 is curved so as to be convex toward one side of the rotor 5. The first curved surface 81 has a first contact point T1 whose tangential direction is parallel to the axial direction and a first vertex Q1 whose tangential direction is parallel to the radial direction. The first contact point T1 is connected to one end 68a of the outer introduction wall surface 68 on one side of the rotor 5. The first contact point T1 is located at the outermost radial point on the first curved surface 81, and the first vertex Q1 is located at the outermost point on the first curved surface 81.

[0024] The second curved surface 82 is a curved surface that smoothly connects to the first curved surface 81 via an inflection point N, and is curved so as to be convex toward the other side. The second curved surface 82 has a second vertex Q2 whose tangential direction is parallel to the radial direction, and a third vertex Q3 whose tangential direction is parallel to the axial direction. The second vertex Q2 is located on the far side of the second curved surface 82, and the third vertex Q3 is located on the far innermost radial side of the second curved surface 82. The third vertex Q3 is located downstream of the second vertex Q2 in the direction of the supply gas flow.

[0025] The second vertex Q2 is located on the other side of the first curved surface 81. With this configuration, at least a portion of the second curved surface 82 is located on the other side of the first vertex Q1 of the first curved surface 81. Because a portion of the outer intake wall surface 85 extends radially inward and toward the other side in the axial direction, the position of the first compressor impeller 10 can be moved further toward the other side than in the conventional configuration. As a result, the axial length of the rotor 5 can be shortened, and a compact supercharger 2 can be realized. Also, because the second vertex Q2 is located on the other side of the first vertex Q1, the area near the outlet of the gas intake passage 80 (more specifically, the outer intake wall surface 85 within the area enclosed by the dashed line B) can be made longer in the axial direction. Because the curvature of the gas intake passage 80 near the outlet can be made gentler, the pressure loss when the first compressor impeller 10 inhales gas can be reduced. In addition, the coolant flowing through the coolant passage 66 cools the supply gas flowing through the axial gas introduction passage 67. As a result, the mass flow rate of the compressed gas G1 (see Figure 1) delivered by the first compressor impeller 10 increases, thereby improving the compressor performance of the supercharger 2.

[0026] As shown in Figure 2, the axial distance from the first vertex Q1 to the second vertex Q2 is defined as M1, the axial distance from the second vertex Q2 to the third vertex Q3 is defined as M2, and the axial distance from the first contact point T1 to the first vertex Q1 is defined as M3. Furthermore, the radial distance from the first vertex Q1 to the second vertex Q2 is defined as R1, the radial distance from the second vertex Q2 to the third vertex Q3 is defined as R2, and the radial distance from the first contact point T1 to the first vertex Q1 is defined as R3.

[0027] In some embodiments, the supercharger 2 is configured such that all of the following equations (1) to (4) are true: M1 < M2 ... Equation (1) M1 < M3 ... Equation (2) R2 > R1 ... Equation (3) R1 > R3 ... Equation (4)

[0028] The gas intake passage 80 is configured to guide the supply gas toward the first compressor impeller 10 located on one side of the rotor 5. Therefore, the longer the length of the passage along the second curved surface 82 toward the other side, the greater the pressure loss in the gas intake passage 80. In this regard, equations (1) and (2) are valid, which allows the axial distance from the first vertex Q1 to the second vertex Q2 to be shortened, thereby reducing the pressure loss in the gas intake passage 80. Also, equation (3) is valid, which allows the radial distance from the second vertex Q2 to the third vertex Q3 to be lengthened, thereby making the curvature of the outer intake wall surface 85 from the second vertex Q2 to the third vertex Q3 gentler. Therefore, the pressure loss in the gas intake passage 80 can be reduced. Also, equation (4) is valid, which allows the radial distance from the first vertex Q1 to the second vertex Q2 to be lengthened, thereby making the curvature of the outer intake wall surface 85 from the first vertex Q1 to the second vertex Q2 gentler. Therefore, the pressure loss in the gas intake passage 80 can be reduced.

[0029] In some embodiments, the supercharger 2 may be configured such that the following equation (5) holds: M2 > M3 ...Equation (5) When equation (5) holds, the area near the outlet of the outer intake wall 85 (more specifically, the outer intake wall 85 within the region enclosed by the dashed line B) can be made longer in the axial direction. Since the curvature of the gas intake passage 80 near the outlet can be made gentler, the pressure loss when the first compressor impeller 10 draws in gas can be reduced.

[0030] As shown in Figure 2, the coolant flow path 66 includes a one-sided coolant flow path 661 located on one side of the inner space 65S of the motor housing 65. In some embodiments, the first curved surface 81 overlaps the one-sided coolant flow path 661 in the radial direction. In other words, the radial range in which the first curved surface 81 is located includes at least a portion of the radial range in which the one-sided coolant flow path 661 is located.

[0031] With the above configuration, the arrangement of the one-sided coolant passage 661 increases the axial range over which the supply gas is cooled. Since the cooling of the supply gas flowing through the gas intake passage 80 can be accelerated compared to the conventional method, the mass flow rate of the supply gas supplied to the first compressor impeller 10 can be increased. In addition, although the rotor 5 becomes longer in the axial direction because the first curved surface 81 curves to one side to avoid the one-sided coolant passage 661, the arrangement of the second curved surface 82 suppresses the axial extension of the rotor 5. As a result, a compact supercharger 2 is realized.

[0032] The flow path cross-sectional area of ​​the gas intake passage 80 according to one embodiment of this disclosure will now be described. As previously stated, the outer surface of the gas intake passage 80 is the outer intake wall 85, and the inner surface of the gas intake passage 80 is the inner intake wall 89. Regarding the position in the flow direction of the supplied gas on the outer intake wall 85, the inlet (i.e., the first contact point T1) is defined as 0%, and the outlet (i.e., the third vertex Q3) is defined as 100%. Furthermore, regarding the position in the flow direction of the supplied gas on the inner intake wall 89, the inlet (point J1 in Figure 2) is defined as 0%, and the outlet (point J2) is defined as 100%.

[0033] Furthermore, the shortest distance between the outer suction wall surface 85 and the inner suction wall surface 89 at the same flow direction position is defined as the flow path height. For example, the flow path height at 100% flow direction position is represented by dimension h in Figure 2. Moreover, the circumference of the gas suction flow path 80 at a specific flow direction position corresponds to the circumference of a circle whose radius is the distance from the midpoint between the outer suction wall surface 85 and the inner suction wall surface 89 at the same flow direction position to the axis 5c, and which is centered on the axis 5c. For example, the circumference of the gas suction flow path 80 at 100% flow direction position can be obtained by multiplying the value obtained by doubling the distance from the midpoint S between the third vertex Q3 and point J2 to the axis 5c (i.e., doubling the dimension Y) by pi.

[0034] In some embodiments, as shown in Figure 3, the flow path cross-sectional area of ​​the gas intake passage 80 decreases continuously from the flow direction position corresponding to the first vertex Q1 (point q1 in Figure 3) to the third vertex Q3, which is the outlet of the outer introduction wall surface 68 (i.e., 100% flow direction position). With this configuration, pressure loss in the gas intake passage 80 can be suppressed, and the supply efficiency of the supply gas toward the first compressor impeller 10 can be increased.

[0035] <Turbine Impeller 40> As shown in Figure 4, the turbine impeller 40 includes a hub body 41 attached to the rotor 5 and a plurality of turbine blades 44 arranged on the hub body 41.

[0036] In some embodiments, the turbine impeller 40 is a mixed-flow turbine impeller. Specifically, the leading edge 46 of each of the multiple turbine blades 44 decreases in diameter as it moves from the shroud side (i.e., the shroud portion 35 side described later) towards the hub side (i.e., the hub body 41 side). In other words, the outer diameter of the hub-side end 46h of the leading edge 46 is smaller than the outer diameter of the shroud-side end 46s of the leading edge 46.

[0037] <Turbine Housing 34> The turbine housing 34 includes a shroud portion 35 that surrounds the plurality of turbine blades 44 of the turbine impeller 40. The shroud portion 35 includes an inner circumferential surface 35a and an outer circumferential surface 35b. The inner circumferential surface 35a is a so-called shroud surface that faces the plurality of turbine blades 44 with a gap between them. The outer circumferential surface 35b is the surface opposite to the inner circumferential surface 35a and constitutes a part of the flow path wall surface of the turbine outlet flow path 36. The inner diameter of the inner circumferential surface 35a increases towards the other side in the axial direction, and the outer diameter of the outer circumferential surface 35b decreases towards the other side in the axial direction.

[0038] <First radially extending wall portion 70> As shown in Figure 4, the first radially extending wall portion 70 according to some embodiments includes a first wall surface 71 facing one side and a second wall surface 72 facing the other side, and the first wall surface 71 has a turbine-side inclined wall surface 73 which constitutes a part of the flow path wall surface of the turbine outlet flow path 36. The turbine-side inclined wall surface 73 is inclined radially so as it moves inward in the radial direction, it moves toward the other side in the axial direction. At least a part of the turbine-side inclined wall surface 73 overlaps radially with the shroud portion 35. In other words, at least a part of the radial range in which the turbine-side inclined wall surface 73 is located is included in the radial range in which the shroud portion 35 is located.

[0039] According to the above configuration, the turbine-side inclined wall surface 73 is formed, allowing the turbine impeller 40 to be moved closer to the other side of the rotor 5 than in the conventional configuration. This shortens the axial length of the first portion 51 of the rotor 5, resulting in a more compact supercharger 2. Furthermore, since the axial length of the first portion 51 is shortened, the load applied to the first portion 51 during operation of the supercharger 2 can be reduced. Therefore, the durability of the supercharger 2 can be improved.

[0040] In some embodiments, a portion of the turbine-side inclined wall surface 73 may be located radially outward with respect to the flow path centerline Ls of the turbine-side scroll flow path 37. When the inclination angle of the turbine-side inclined wall surface 73 is constant, the longer the radial length of the turbine-side inclined wall surface 73, the longer the axial length of the turbine-side inclined wall surface 73, and the shorter the axial length of the rotor 5 can be. According to this configuration, the turbine-side inclined wall surface 73 includes a portion that overlaps with the shroud portion 35 in the radial direction and a portion that is located radially outward with respect to the flow path centerline Ls, making the turbine-side inclined wall surface 73 longer in the radial direction. Therefore, the axial length of the first portion 51 of the rotor 5 can be further shortened.

[0041] In some embodiments, nozzle vanes 55 are positioned between the outer surface 35b of the shroud and the turbine-side inclined wall surface 73. The nozzle vanes 55 may be either fixed or movable. This configuration makes it possible to reduce the pressure loss of the exhaust gas G3 flowing into the turbine impeller 40.

[0042] In some embodiments, the first radially extending wall portion 70 is constructed separately from the turbine housing 34 and the first compressor housing 33 (see Figure 1). This configuration reduces constraints in manufacturing the first radially extending wall portion 70, allowing the shape of the turbine-side inclined wall surface 73 to be a desired shape.

[0043] <First Compressor Impeller 10, First Compressor Housing 33> As shown in Figure 4, in some embodiments, the second wall surface 72 of the first radially extending wall portion 70 includes a compressor-side inclined wall surface 78 that constitutes a part of the flow path wall surface of the diffuser flow path 31d. The first compressor housing 33 includes a housing-side inclined wall surface 29 that faces the compressor-side inclined wall surface 78. The compressor-side inclined wall surface 78 and the housing-side inclined wall surface 29 define the diffuser flow path 31d. The diffuser flow path 31d is inclined radially such that it moves radially outward toward one side in the axial direction. That is, each of the compressor-side inclined wall surface 78 and the housing-side inclined wall surface 29 is inclined radially such that it moves radially outward toward one side in the axial direction.

[0044] According to the above configuration, since the inlet portion of the diffuser flow path 31d can be moved closer to the other side in the axial direction, the first compressor impeller 10 can be moved closer to the other side than before. As a result, the axial length of the first portion 51 of the rotor 5 can be shortened, and the supercharger 2 can be made more compact.

[0045] Also, in some embodiments, the first compressor impeller 10 includes a plurality of first compressor blades 11 arranged at intervals in the circumferential direction, and the trailing edge 12 of the first compressor blade 11 has a reduced diameter from the shroud side to the hub side of the first compressor impeller 10. That is, the outer diameter of the hub side end 12h of the trailing edge 12 is smaller than the outer diameter of the shroud end 12s of the trailing edge 12. According to this configuration, since the pressure loss when the compressed gas G1 (see FIG. 1) sent out from the trailing edge 12 of the first compressor blade 11 flows into the diffuser flow path 31d can be reduced, the operating efficiency of the supercharger 2 can be increased.

[0046] <Details of the supercharger 2>FIG. 5 is a schematic diagram showing the details of the supercharger 2 according to an embodiment of the present disclosure. The supercharger 2 further includes an other-side journal bearing B2, a second compressor impeller 20, and a thrust bearing 59.

[0047] The other-side journal bearing B2 is arranged on the other side of the rotor 61 of the motor 60. The other-side journal bearing B2 supports the rotor 5 on the other side in the axial direction. The second compressor impeller 20 is arranged on the other side of the rotor 5. More specifically, the second compressor impeller 20 is arranged at the second portion 52 which is a portion of the rotor 5 that protrudes to the other side from the other-side journal bearing B2. The thrust bearing 59 is arranged at the second portion 52 between the other-side journal bearing B2 and the second compressor impeller 20.

[0048] The housing 8 further includes a second compressor housing 25 that houses the second compressor impeller 20. A second compressor flow path 28 is formed in the second compressor housing 25. The second compressor flow path 28 is configured to guide the low-pressure compressed gas sent out by the second compressor impeller 20 toward the first compressor impeller 10. That is, the low-pressure compressed gas is supplied to the first compressor impeller 10 as the aforementioned supply gas.

[0049] According to the above configuration, the pressure of the compressed gas G1 generated from the supply gas by the first compressor impeller 10 can be increased.

[0050] The motor housing 65 includes an other-side bearing housing 90 that houses the other-side journal bearing B2 and the thrust bearing 59. The other-side journal bearing B2 is supported by the other-side bearing housing 90.

[0051] The other-side bearing housing 90 defines a thrust bearing space Sb in which the thrust bearing 59 is disposed and an other-side journal bearing space Sj in which the other-side journal bearing B2 is disposed. The thrust bearing space Sb and the other-side journal bearing space Sj communicate with each other. Further, a radially extending gas flow path 98 that communicates with the thrust bearing space Sb and extends along the radial direction is formed in the other-side bearing housing 90. The radially extending gas flow path 98 is open toward the outside in the radial direction.

[0052] A part of the compressed gas G1 generated by the first compressor impeller 10 flows to another location different from the supply line L1 (see FIG. 1) as leakage gas. The leakage gas includes first leakage gas. The first leakage gas sequentially passes through a first gap P1 between the first compressor housing 33 and the one-side journal bearing B1 and a motor gap Pm between the rotor 61 and the stator 62 (arrow A2). A part of the first leakage gas reaches the thrust bearing space Sb via the other-side journal bearing space Sj. The first leakage gas is discharged to the outside of the supercharger 2 from the radially extending gas flow path 98.

[0053] According to the above configuration, a portion of the compressed gas G1 compressed by the first compressor impeller 10 flows into the thrust bearing space Sb as the first leak gas. Subsequently, the first leak gas is discharged to the outside through the radially extending gas flow path 98. This allows the first leak gas to be used for cooling the thrust bearing 59.

[0054] The other bearing housing 90 includes a cylindrical wall portion 91 surrounding the other journal bearing B2, and a second radially extending wall portion 92 extending radially outward from the cylindrical wall portion 91. The second radially extending wall portion 92 is located on one side of the disk portion 58 of the thrust bearing 59. An axial through passage 97 is formed in the second radially extending wall portion 92, and the axial through passage 97 connects the inner space 65S of the motor housing 65 with the thrust bearing space Sb.

[0055] A portion of the first leak gas that passes through the motor gap Pm does not flow into the other side journal bearing space Sj, but instead flows into the inner space 65S of the motor housing 65 (arrow A3). According to the above configuration, the first leak gas flows into the thrust bearing space Sb via the axial through passage 97. Therefore, the cooling of the thrust bearing 59 can be promoted.

[0056] <Heat Recovery System 1A(1)> Figure 6 is a schematic diagram showing the details of the heat recovery system 1A(1) according to the first embodiment. The heat recovery device 3A(3) is a polymer electrolyte fuel cell (PEFC) configured to generate electricity using compressed gas G1 as an oxidizing gas and a fuel gas such as hydrogen gas. In this example, the compressed gas G1 is air. The heat contained in the compressed gas G1 is recovered in the heat recovery device 3A, and the recovered heat is used to heat the cells that make up the fuel cell. With the above configuration, electricity can be generated using compressed gas G1 as an oxidizing gas.

[0057] <Heat Recovery System 1B(1)> Figure 7 is a schematic diagram showing the details of the heat recovery system 1B(1) according to the second embodiment. The heat recovery system 1B is configured to cool the object to be cooled 100 by forming a Brayton cycle in which the refrigerant circulates while maintaining a gaseous state. The heat recovery device 3B(3) is a heat exchanger incorporated into the Brayton cycle. The heat exchanger is configured to exchange heat between the refrigerant gas discharged from the object to be cooled 100 and the compressed gas G1. The compressed gas G1 cooled through heat exchange flows into the turbine impeller 40 as exhaust gas G3. As it passes through the turbine impeller 40, the temperature of the exhaust gas G3 decreases further and flows into the object to be cooled 100 as refrigerant gas. In this example, the refrigerant gas cooled by the heat recovery device 3B flows into the second compressor impeller 20, and the second compressor impeller 20 generates low-pressure compressed gas from the refrigerant gas. Furthermore, the compressed gas G1 flowing from the first compressor impeller 10 toward the heat recovery device 3B may be cooled by a pre-cooling heat exchanger 101 such as a fan. With the above configuration, the compressed gas G1 can be used as a refrigerant gas to cool the object to be cooled 100.

[0058] <Summary> The contents described in the above-mentioned embodiments can be understood, for example, as follows:

[0059] 1) A supercharger (2) according to at least one embodiment of the present disclosure includes: a rotor (5); a first compressor impeller (10) disposed on one side of the rotor; a turbine impeller (40) disposed back-to-back with the first compressor impeller on the one side of the rotor relative to the first compressor impeller; a motor (60) including a rotor (61) disposed on the other side of the rotor relative to the first compressor impeller and a stator (62) disposed around the rotor; and a housing (8) housing at least the motor and the first compressor impeller, wherein an axial gas introduction passage (67) extending outward from the stator and along the axial direction of the rotor is formed thereon, and a gas intake passage (80) for guiding gas (supply gas) introduced by the axial gas introduction passage to the first compressor impeller, the housing includes an outer intake wall surface (85) that forms the outer surface of the gas intake passage in a cross section along the axial direction of the rotor. The outer intake wall surface includes a first curved surface (81) that curves convex toward one side of the rotor, and in the cross-section has a first vertex (Q1) located furthest toward the one side of the rotor on the first curved surface, and a second curved surface (82) located downstream of the first curved surface in the gas flow direction and curves convex toward the other side of the rotor, and in the cross-section has a second vertex (Q2) located furthest toward the other side of the rotor on the second curved surface, wherein the second vertex is located on the other side of the rotor relative to the first vertex.

[0060] According to the configuration described in 1) above, at least a portion of the second curved surface is located on the other side of the first vertex of the first curved surface. Since a portion of the outer intake wall extends radially inward of the rotor and toward the other side of the rotor, the position of the first compressor impeller can be moved further to the other side than in the conventional configuration. As a result, the axial length of the rotor can be shortened, and a compact supercharger can be realized. In addition, since the second vertex is located on the other side of the first vertex, the axial length near the outlet of the gas intake passage can be lengthened. Since the curvature of the gas intake passage near the outlet can be made gentler, the pressure loss when the first compressor impeller draws in gas can be reduced.

[0061] 2) In some embodiments, the supercharger is as described in 1) above, wherein the second curved surface is located downstream of the second vertex in the gas flow direction and further has a third vertex (Q3) located on the innermost radial side of the rotor on the second curved surface in the cross-section, and the axial distance from the first vertex to the second vertex is defined as M1, and the axial distance from the second vertex to the third vertex is defined as M2, such that M1 < M2.

[0062] Since the gas intake passage is configured to guide gas toward the first compressor impeller on one side of the rotor, the longer the passage length along the second curved surface toward the other side, the greater the pressure loss in the gas intake passage. In this respect, according to the configuration of 2) above, the axial distance from the first vertex to the second vertex can be shortened, and the pressure loss in the gas intake passage can be reduced.

[0063] 3) In some embodiments, the supercharger is as described in 2) above, wherein the housing includes an outer introduction wall surface (68) that forms the outer circumferential surface of the axial gas introduction passage in the cross-section, the first curved surface has a first contact point (T1) that is connected to one end (68a) of the outer introduction wall surface on one side of the rotor in the cross-section, and the axial distance from the first contact point to the first vertex is defined as M3, such that M1 < M3.

[0064] According to the configuration described in 3) above, the axial distance from the first vertex to the second vertex can be shortened, and pressure loss in the gas intake passage can be reduced.

[0065] 4) In some embodiments, the supercharger is as described in 2) or 3) above, where R1 is defined as the radial distance from the first vertex to the second vertex, and R2 is defined as the radial distance from the second vertex to the third vertex, such that R2 > R1.

[0066] According to the configuration described in 4) above, the radial distance from the second vertex to the third vertex can be increased, which allows for a gentler curvature of the outer suction wall surface from the second vertex to the third vertex. As a result, pressure loss in the gas suction passage can be reduced.

[0067] 5) In some embodiments, the supercharger is as described in any of 2) to 4) above, wherein the housing includes an outer introduction wall surface (68) that forms the outer circumferential surface of the axial gas introduction passage in the cross-section, the first curved surface has a first contact point (T1) that is connected to one end (68a) of the outer introduction wall surface on one side of the rotor in the cross-section, and R1 is defined as the radial distance from the first vertex to the second vertex, and R3 is defined as the radial distance from the first contact point to the first vertex, such that R1 > R3 holds.

[0068] According to the configuration described in 5) above, the radial distance from the first vertex to the second vertex can be increased, which allows for a gentler curvature of the outer suction wall surface from the first vertex to the second vertex. As a result, pressure loss in the gas suction passage can be reduced.

[0069] 6) In some embodiments, a supercharger according to any of 1) to 5) above, wherein the housing includes an inner intake wall surface (89) that forms the inner surface of the gas intake passage in a cross section along the axial direction of the rotor, the inlet and outlet are defined as 0% and 100% respectively for the flow direction position on the inner intake wall surface, the inlet and outlet are defined as 0% and 100% respectively for the flow direction position on the outer intake wall surface, the flow path cross-sectional area is defined as the value obtained by multiplying the flow path height, which is the shortest distance between the inner intake wall surface and the outer intake wall surface at the same flow direction position, by the circumference of the gas intake passage at the same flow direction position, and the flow path cross-sectional area of ​​the gas intake passage decreases continuously from the flow direction position corresponding to the first vertex to the flow direction position corresponding to the outlet of the outer intake wall surface.

[0070] According to the configuration described in 6) above, the cross-sectional area of ​​the gas intake passage decreases continuously from the first apex to the outlet, thereby suppressing pressure loss in the gas intake passage and improving the gas supply efficiency to the first compressor impeller.

[0071] 7) In some embodiments, a supercharger according to any one of 1) to 6) above, wherein the housing includes a motor housing (65) for housing the motor, the motor housing has a coolant flow path (66) formed therein between the stator and the axial gas introduction passage in the radial direction of the rotor, the coolant flow path includes a one-side coolant flow path (661) located on one side of the rotor beyond the inner space (65S) of the motor housing, and the first curved surface overlaps the one-side coolant flow path in the radial direction of the rotor.

[0072] According to the configuration described in 7) above, the arrangement of the one-sided coolant passage allows for more effective cooling of the gas flowing through the gas intake passage than in conventional designs, thereby increasing the mass flow rate of the gas supplied to the first compressor impeller. Furthermore, although the rotor becomes longer in the axial direction due to the one-sided coolant passage being located on one side of the inner space, the arrangement of the second curved surface suppresses this axial extension of the rotor. As a result, a compact supercharger is realized.

[0073] 8) In some embodiments, a supercharger according to any one of 1) to 7) above, wherein the housing is a turbine housing for housing the turbine impeller, and further includes a turbine housing (34) in which a turbine-side passage (38) for exhaust gas to flow toward the turbine impeller is formed, and the supercharger further comprises a nozzle vane (55) positioned at the outlet of the turbine-side passage.

[0074] According to the configuration described in 8) above, the nozzle vanes adjust the direction of the exhaust gas flow into the turbine impeller, thereby reducing the pressure loss when the exhaust gas flows into the turbine impeller.

[0075] 9) In some embodiments, a supercharger according to any of 1) to 8) above further comprises a second compressor impeller (20) disposed on the other side of the rotor, wherein the low-pressure compressed gas compressed by the second compressor impeller is sent to the first compressor impeller.

[0076] According to the configuration described in 9) above, the pressure of the compressed gas generated by the first compressor impeller can be increased.

[0077] 10) In some embodiments, the supercharger described in 9) further comprises: a thrust bearing (59) disposed in the rotor between the rotor and the second compressor impeller; and a other bearing housing (90) defining the thrust bearing space in which the thrust bearing is disposed, wherein the other bearing housing has a radially extending gas passage (98) formed therein for guiding leak gas from the compressed gas (G1) delivered by the first compressor impeller, which has flowed from the first compressor impeller through the motor gap (Pm) between the rotor and the stator into the thrust bearing space, to the outside along the radial direction of the rotor.

[0078] According to the configuration described in 10) above, a portion of the compressed gas compressed by the first compressor impeller flows into the thrust bearing space as leak gas. Subsequently, the leak gas is discharged to the outside through the radially extending gas flow path. This allows a portion of the leak gas to be used for cooling the thrust bearing.

[0079] 11) In some embodiments, the supercharger described in 10) further comprises a journal bearing (other-side journal bearing B2) disposed on the rotor between the thrust bearing and the rotor and housed in the other-side bearing housing, wherein the housing includes a motor housing (65) that houses the motor, and the other-side bearing housing includes a cylindrical wall portion (91) surrounding the journal bearing and a radially extending wall portion (second radially extending wall portion 92) extending radially outward from the cylindrical wall portion, wherein an axial through passage (97) is formed in the radially extending wall portion, which penetrates in the axial direction of the rotor and connects the inner space of the motor housing with the thrust bearing space.

[0080] According to the configuration described in 11) above, the leak gas from the compressed gas compressed by the first compressor impeller that flows into the inner space of the motor housing also flows into the thrust bearing space via the axial through passage. Therefore, the cooling of the thrust bearing can be promoted.

[0081] 12) A heat recovery system (1) according to at least one embodiment of the present disclosure is a heat recovery system comprising: a supercharger as described in 1) or 2) above; and a heat recovery device configured to recover heat from compressed gas compressed by the first compressor impeller, wherein the supercharger is configured such that the gas from which the heat has been recovered by the heat recovery device flows into the turbine impeller as exhaust gas.

[0082] According to the configuration in 12) above, the same technical advantages as in 1) above can be obtained.

[0083] 13) In some embodiments, the heat recovery system is as described in 12) above, wherein the heat recovery device is a fuel cell configured to generate electricity using an oxidizing gas as the compressed gas and a fuel gas, and the supercharger is configured such that the oxidizing gas discharged from the fuel cell flows into the turbine side passage as the exhaust gas.

[0084] According to the configuration described in item 13) above, electricity can be generated using compressed gas as an oxidizing gas.

[0085] 14) In some embodiments, the heat recovery system is as described in 12) above, wherein the heat recovery device is a heat exchanger constituting a Brayton cycle, and is configured to recover heat from the compressed gas sent from the first compressor impeller into the refrigerant gas discharged from the object to be cooled, and the supercharger is configured such that the exhaust gas, which is the compressed gas from which heat has been recovered in the heat exchanger, flows into the turbine impeller.

[0086] According to the configuration described in item 14) above, compressed gas can be used as a refrigerant gas to cool the object to be cooled.

[0087] 1A, 1B (1): Heat recovery system 2: Supercharger 3A, 3B (3): Heat recovery device 5: Rotor 5c: Axle center 8: Housing 10: First compressor impeller 11: First compressor blade 12: Trailing edge 12h: Hub side end 12s: Shroud end 20: Second compressor impeller 25: Second compressor housing 28: Second compressor flow path 29: Housing side inclined wall surface 30: First housing 31: First compressor side flow path 31d: Diffuser flow path 32: Exhaust passage 33: First compressor housing 34: Turbine housing 35: Shroud section 35a: Shroud inner surface 35b: Shroud outer surface 36: Turbine outlet flow path 37 : Turbine-side scroll passage 38 : Turbine-side passage 40 : Turbine impeller 41 : Hub body 44 : Turbine blade 46 : Leading edge 46h : Hub-side end 46s : Shroud-side end 51 : First section 52 : Second section 55 : Nozzle vane 58 : Disc section 59 : Thrust bearing 60 : Motor 61 : Rotor 62 : Stator 63 : Stator coil 65 : Motor housing 65S : Inner space 66 : Coolant passage 67 : Axial gas introduction passage 68 : Outer introduction wall surface 68a : One end 69 : Inner introduction wall surface 70 : First radially extending wall section 71 : First wall surface 72 : Second wall surface 73 : Turbine-side inclined wall surface 78 : Compressor-side inclined wall surface 80 : Gas intake passage 81: First curved surface 82: Second curved surface 85: Outer intake wall surface 89: Inner intake wall surface 90: Other side bearing housing 91: Cylindrical wall portion 92: Second radially extending wall portion 97: Axial through passage 98: Radially extending gas passage 100: Cooling target 101: Pre-cooling heat exchanger 661: One side coolant passage A2,A3: Arrow B: Dotted line B1: One side journal bearing B2: Other side journal bearing G1: Compressed gas G3: Exhaust gas L1: Supply line L2: Discharge line Ls: Flow path centerline N: Inflection point P1: First gap Pm: Motor gap Q1: First vertex Q2: Second vertex Q3: Third vertex S: Midpoint Sb: Thrust bearing space Sj: Other side journal bearing space T1: First contact point h, Y: Dimensions

Claims

1. A motor comprising: a rotor; a first compressor impeller disposed on one side of the rotor; a turbine impeller disposed back-to-back with the first compressor impeller on the one side of the rotor relative to the first compressor impeller; a rotor disposed on the other side of the rotor relative to the first compressor impeller; and a stator disposed around the rotor; and a housing that at least houses the motor and the first compressor impeller, wherein an axial gas introduction passage extending outward from the stator and along the axial direction of the rotor is formed in the housing, and a gas intake passage for guiding the gas introduced by the axial gas introduction passage to the first compressor impeller, wherein the housing includes an outer intake wall surface that forms the outer surface of the gas intake passage in a cross-section along the axial direction of the rotor, and the outer intake wall surface is a first curved surface that curves convex toward the one side of the rotor, and in the cross-section, has a first curved surface having a first vertex that is furthest from the one side of the rotor on the first curved surface, A supercharger having a second curved surface located downstream of the first curved surface in the gas flow direction and curved so as to be convex toward the other side of the rotor, the second curved surface having a second vertex that is located furthest to the other side of the rotor on the second curved surface in the cross-section, wherein the second vertex is located on the other side of the rotor relative to the first vertex.

2. The supercharger according to claim 1, wherein the second curved surface is located downstream of the second vertex in the gas flow direction and further has a third vertex located on the second curved surface in the cross-section, the axial distance from the first vertex to the second vertex is defined as M1, and the axial distance from the second vertex to the third vertex is defined as M2, such that M1 < M2.

3. The supercharger according to claim 2, wherein the housing includes an outer introduction wall surface that forms the outer circumferential surface of the axial gas introduction passage in the cross-section, the first curved surface has a first contact point that connects to one end of the outer introduction wall surface on one side of the rotor in the cross-section, and the axial distance from the first contact point to the first vertex is defined as M3, such that M1 < M3 holds.

4. The supercharger according to claim 2 or 3, wherein the radial distance from the first vertex to the second vertex is defined as R1, and the radial distance from the second vertex to the third vertex is defined as R2, and R2 > R1 is satisfied.

5. The supercharger according to claim 2 or 3, wherein the housing includes an outer introduction wall surface that forms the outer circumferential surface of the axial gas introduction passage in the cross-section, the first curved surface has a first contact point that connects to one end of the outer introduction wall surface on one side of the rotor in the cross-section, and the radial distance from the first vertex to the second vertex is defined as R1, and the radial distance from the first contact point to the first vertex is defined as R3, such that R1 > R3.

6. The supercharger according to any one of claims 1 to 3, wherein the housing includes an inner intake wall surface that forms the inner surface of the gas intake passage in a cross section along the axial direction of the rotor, the inlet and outlet are defined as 0% and 100% respectively at the flow direction positions on the inner intake wall surface, the inlet and outlet are defined as 0% and 100% respectively at the flow direction positions on the outer intake wall surface, the flow path cross-sectional area is defined as the value obtained by multiplying the flow path height, which is the shortest distance between the inner intake wall surface and the outer intake wall surface at the same flow direction position, by the circumference of the gas intake passage at the same flow direction position, and the flow path cross-sectional area of ​​the gas intake passage decreases continuously from the flow direction position corresponding to the first vertex to the flow direction position corresponding to the outlet of the outer intake wall surface.

7. The supercharger according to any one of claims 1 to 3, wherein the housing includes a motor housing for housing the motor, the motor housing has a coolant flow path formed therein between the stator and the axial gas introduction passage in the radial direction of the rotor, the coolant flow path includes a one-side coolant flow path located on one side of the rotor beyond the inner space of the motor housing, and the first curved surface overlaps the one-side coolant flow path in the radial direction of the rotor.

8. The supercharger according to any one of claims 1 to 3, wherein the housing is a turbine housing for housing the turbine impeller, and further comprises a turbine-side passage formed for exhaust gas to flow toward the turbine impeller, and the supercharger further comprises a nozzle vane disposed at the outlet of the turbine-side passage.

9. The supercharger according to any one of claims 1 to 3, further comprising a second compressor impeller disposed on the other side of the rotor, wherein the low-pressure compressed gas compressed by the second compressor impeller is sent to the first compressor impeller.

10. The supercharger according to claim 9, further comprising: a thrust bearing disposed in the rotor between the rotor and the second compressor impeller; and a other bearing housing defining the thrust bearing space in which the thrust bearing is disposed, wherein the other bearing housing has a radially extending gas passage formed therein for guiding leak gas, which is compressed gas delivered by the first compressor impeller and has flowed from the first compressor impeller through the motor gap between the rotor and the stator into the thrust bearing space, to the outside along the radial direction of the rotor.

11. The supercharger according to claim 10, further comprising a journal bearing disposed in the rotor between the thrust bearing and the rotor and housed in the other bearing housing, wherein the housing includes a motor housing for housing the motor, and the other bearing housing includes a cylindrical wall portion surrounding the journal bearing and a radially extending wall portion extending radially outward from the cylindrical wall portion, wherein an axial through passage is formed in the radially extending wall portion, which penetrates the rotor in the axial direction and connects the inner space of the motor housing with the thrust bearing space.

12. A heat recovery system comprising: a supercharger according to claim 1 or 2; and a heat recovery device configured to recover heat from compressed gas compressed by the first compressor impeller, wherein the supercharger is configured such that the gas from which the heat has been recovered by the heat recovery device flows into the turbine impeller as exhaust gas.

13. The heat recovery system according to claim 12, wherein the heat recovery device is a fuel cell configured to generate electricity using an oxidizing gas as the compressed gas and a fuel gas, and the supercharger is configured such that the oxidizing gas discharged from the fuel cell flows into the turbine impeller as the exhaust gas.

14. The heat recovery system according to claim 12, wherein the heat recovery device is a heat exchanger constituting a Brayton cycle, and is configured to recover heat from the compressed gas delivered from the first compressor impeller into the refrigerant gas discharged from the object to be cooled, and the supercharger is configured such that the exhaust gas, which is the compressed gas from which heat has been recovered in the heat exchanger, flows into the turbine impeller.

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