Supercharger and heat recovery system

Abstract

A first housing of this supercharger includes: a shroud portion including an inner peripheral surface that surrounds a turbine impeller and has an inner diameter that increases toward one side of a rotor, and an outer peripheral surface that is formed on the opposite side to the inner peripheral surface and has an outer diameter that decreases toward the one side; and a first radially extending wall portion formed between a first compressor-side flow passage and a turbine-side flow passage. The first radially extending wall portion has a turbine-side inclined wall surface that is inclined with respect to the radial direction so as to approach the other side of the rotor with increasing distance inward in the radial direction of the rotor, at least a portion of the turbine-side inclined wall surface overlapping the shroud portion in the radial direction.

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] The supercharger according to at least one embodiment of the present disclosure includes: 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 with respect to the first compressor impeller; and a first housing that at least houses the turbine impeller and the first compressor impeller, the first housing having a first compressor side flow path through which compressed gas compressed by the first compressor impeller flows and a turbine side flow path through which exhaust gas flows toward the turbine impeller. The first housing includes a shroud portion including an inner peripheral surface that surrounds the turbine impeller and has an inner diameter that increases toward the one side of the rotor, and an outer peripheral surface that is formed on the opposite side of the inner peripheral surface and has an outer diameter that decreases toward the one side; and a first radially extending wall portion formed between the first compressor side flow path and the turbine side flow path. The first radially extending wall portion is a turbine side inclined wall surface that is inclined with respect to the radial direction so as to face the other side of the rotor as it goes toward the inner side in the radial direction of the rotor, and at least a part thereof overlaps with the shroud portion in the radial direction.

[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-side passage of the first housing 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 turbine impeller according to one embodiment. This is another schematic diagram of a turbine impeller according to one embodiment. This is an enlarged view of the first radially extending wall (first embodiment). This is a schematic diagram of the axial hole in the first radially extending wall. This is an enlarged view of the first radially extending wall (second embodiment). This is a schematic diagram of the fins in the first radially extending wall. This is an enlarged view of the turbine impeller and the first compressor 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 turbine housing 34 includes a shroud portion 35 that surrounds the multiple turbine blades 44 of the turbine impeller 40. 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, respectively. The inner circumferential end face 79, which is the radially inner end face of the first radially extending wall portion 70, extends radially. 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 this disclosure is not limited thereto. Hereinafter, the first radially extending wall portion 70, the first compressor housing 33, and the turbine housing 34 may be collectively referred to as the "first housing 30".

[0017] In some embodiments of the supercharger 2, a sleeve 6 is provided on a first portion 51 of the rotor 5 between the first compressor impeller 10 and the turbine impeller 40. The outer circumferential surface 6a of the sleeve 6 faces the inner circumferential end surface 79 of the first radially extending wall portion 70.

[0018] The operation overview of the turbocharger 2 shown in Figure 1 is as follows: The first compressor impeller 10, which rotates together with the rotor 5, generates compressed gas G1 by compressing the supply gas introduced by 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.

[0019] When the supercharger 2 is operating, some of the compressed gas G1 flows to a location other than the supply line L1. This compressed gas G1 will be referred to as "leak gas" below. The leak gas includes the first leak gas (arrow A1 in Figure 2) that passes between the inner circumferential end face 79 and the outer circumferential surface 6a of the sleeve and reaches the turbine impeller 40.

[0020] <Turbine Impeller 40> Referring to Figures 2 and 3, several embodiments of the turbine impeller 40 will be described. 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. The hub body 41 includes a hub surface 42 on which the plurality of turbine blades 44 are erected and a back surface 43 facing the other side in the axial direction. The plurality of turbine blades 44 are spaced apart in the circumferential direction. The back surface 43 is connected to the hub-side end 46h of the leading edge 46 of each of the plurality of turbine blades 44.

[0021] The hub body 41 has a boss portion 47 located on one side relative to the plurality of turbine blades 44, and a back plate portion 45 located on the other side relative to the plurality of turbine blades 44. The back plate portion 45 includes the entire portion of the back surface 43 described above.

[0022] In some embodiments, the back plate portion 45 has a plurality of scallops 48 formed thereon. Each scallop 48 is a recess that is recessed toward the axis 5c of the rotor 5 from the hub-side end 46h of the leading edge 46 of each turbine blade 44. Each scallop 48 is located between the hub-side ends 46h of the leading edges 46 of two circumferentially adjacent turbine blades 44. Each scallop 48 has a concave surface 49 that is recessed toward the axis 5c.

[0023] According to the above configuration, the scallop 48 can guide the first leak gas passing between the inner circumferential end face 79 and the outer circumferential surface 6a of the sleeve between two adjacent turbine blades 44. The first leak gas expands as it passes between the two turbine blades 44 and is discharged from the exhaust passage 32. The turbine impeller 40 can rotate using the energy recovered from the first leak gas, thus realizing a supercharger 2 with improved operating efficiency. Note that the supercharger 2 does not necessarily have to be equipped with a sleeve 6. For example, the hub body 41 may further include a small-diameter boss portion protruding from the back plate portion 45 to the other side, and the inner circumferential end face 79 of the first radially extending wall portion 70 may face the outer circumferential surface of the small-diameter boss portion. The first leak gas passes between the first radially extending wall portion 70 and the small-diameter boss portion. Even in this case, the above technical advantages can be obtained.

[0024] As shown in Figures 2 and 3, D1 is defined as the inner diameter of the inner circumferential end face 79 of the first radially extending wall portion 70, D2 as the maximum outer diameter of the back plate portion 45, D3 as the maximum outer diameter of the boss portion 47, D4 as the outer diameter of the outer circumferential surface 6a of the sleeve, and L as the shortest radial distance between the concave surface 49 of the scallop 48 and the axis 5c.

[0025] In some embodiments, the supercharger 2 is configured such that equations (1) to (3) all hold true. D1 ≥ (D2 + D3) / 2 ... Equation (1) D1 ≥ 2L ... Equation (2) D4 < D2 ... Equation (3)

[0026] As equation (1) holds true, the inner circumferential end face 79 of the first radially extending wall portion 70 is located radially further outward than in the conventional configuration, allowing the first leak gas that has passed between the inner circumferential end face 79 and the outer circumferential surface 6a of the sleeve to easily pass through the scallop 48. Therefore, energy recovery of the first leak gas by the turbine impeller 40 can be promoted. Furthermore, as equation (2) holds true, the inner circumferential end face 79 is located radially further outward than the bottom of the concave surface 49 of the scallop 48, allowing the first leak gas that has passed inside the inner circumferential end face 79 to pass through the scallop 48 even more easily. Furthermore, as equation (3) holds true, the flow path for the first leak gas formed between the inner circumferential end face 79 and the outer circumferential surface 6a of the sleeve is located radially further inward than the outermost diameter portion of the back plate portion 45. Therefore, the first leak gas can pass through the scallop 48 even more easily.

[0027] As shown in Figure 2, 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) to 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. With the above configuration, since the leading edge 46 of the turbine impeller 40 extends at an inclination with respect to the axial direction, the first leak gas can easily flow between two adjacent turbine blades 44. Therefore, the energy recovery of the first leak gas by the turbine impeller 40 can be promoted. Furthermore, with the above configuration, the turbine impeller 40 can be made more compact.

[0028] Returning to Figure 1, in the configuration in which the heat recovery device 3 is provided, the temperature of the compressed gas G1 delivered by the first compressor impeller 10 is higher than the temperature of the exhaust gas G3 flowing into the turbine impeller 40. That is, the energy contained in the first leak gas per unit mass is higher than the energy contained in the exhaust gas G3 flowing into the turbine impeller 40 per unit mass. Therefore, as the turbine impeller 40 recovers energy from the first leak gas, the rotational speed of the turbine impeller 40 increases reliably, and the operating efficiency of the turbocharger 2 improves.

[0029] <Details of the First Radially Extended Wall 70> Figures 4A and 4B are schematic diagrams of the details of the first radially extended wall 70A (70) according to the first embodiment, and Figures 5A and 5B are schematic diagrams of the details of the first radially extended wall 70B (70) according to the second embodiment. In both the first and second embodiments, the first leak gas can pass between the inner circumferential end face 79 and the outer circumferential surface 6a of the sleeve to one side. In Figures 4B and 5B, the drawing is such that the vertical direction of the paper coincides with the circumferential direction, and the direction of arrow R indicates the rotation direction of the turbine impeller 40.

[0030] As shown in Figure 4A, the inner circumferential end face 79 of the first radially extending wall portion 70A faces the outer circumferential surface 6a of the sleeve, separated by a small gap Gs. No members are provided on the inner circumferential end face 79 or the outer circumferential surface 6a of the sleeve. The first radially extending wall portion 70A (70) may have a plurality of axial holes 75 that penetrate in the axial direction. The plurality of axial holes 75 are located radially inward from the shroud-side end 46s of the leading edge 46 of the turbine impeller 40, and radially outward from the inner circumferential end face 79. As shown in Figure 4B, each axial hole 75 extends inclined with respect to the axial direction, specifically, it extends inclined toward the downstream side in the rotational direction of the turbine impeller 40 as it approaches the turbine blade 44 in the axial direction.

[0031] According to the above configuration, a portion of the first leak gas is discharged toward the turbine impeller 40 from a plurality of axial holes 75. Since the outlets of the axial holes 75 face downstream in the rotational direction of the turbine impeller 40, the pressure loss when the discharged first leak gas flows between two adjacent turbine blades 44 can be reduced. Therefore, the energy recovery of the first leak gas by the turbine impeller 40 can be promoted.

[0032] As shown in Figure 5A, an installation body 76 is interposed between the inner circumferential end face 79 of the first radially extending wall portion 70B and the outer circumferential sleeve surface 6a of the sleeve 6. The installation body 76 is, as an example, a plurality of fins 77 erected from the inner circumferential end face 79. The plurality of fins 77 are arranged at intervals in the circumferential direction. Each fin 77 is plate-shaped with thickness in the circumferential direction. As shown in Figure 5B, each fin 77 extends inclined with respect to the axial direction, and specifically, as it approaches the turbine blade 44 in the axial direction, it extends inclined toward the downstream side in the rotational direction of the turbine impeller 40.

[0033] According to the above configuration, the first leak gas passing through the inner circumference of the inner end face 79 is guided downstream in the rotational direction of the turbine impeller 40 by the multiple fins 77, thereby reducing the pressure loss when the discharged first leak gas flows between two adjacent turbine blades 44. Therefore, the energy recovery of the first leak gas by the turbine impeller 40 can be promoted.

[0034] This disclosure is not limited to the embodiments shown in Figures 4A, 4B, 5A, and 5B. For example, an embodiment may be adopted in which a plurality of axial holes 75 (see Figures 4A and 4B) are not formed in the first radially extending wall portion 70A (this embodiment is shown in Figure 6). Alternatively, an embodiment may be adopted in which the mounting body 76 (see Figure 5A) replaces the fins 77 as a sealing device. The sealing device may be a labyrinth seal consisting of protrusions formed on the inner circumferential end face 79 and the outer circumferential surface 6a of the sleeve. Alternatively, the sealing device may be an O-ring fitted into an annular groove extending circumferentially on the outer circumferential surface 6a of the sleeve, in which case no member is provided on the inner circumferential end face 79.

[0035] <Shroud Section 35> As shown in Figure 6, the shroud section 35 according to some embodiments includes an inner shroud surface 35a and an outer shroud surface 35b. The inner shroud surface 35a is a so-called shroud surface that faces the plurality of turbine blades 44 with a gap between them. The outer shroud surface 35b is the surface opposite to the inner shroud surface 35a and constitutes a part of the flow path wall surface of the turbine outlet flow path 36. Both the inner shroud surface 35a and the outer shroud surface 35b are formed such that their diameters increase towards one side in the axial direction.

[0036] <Turbine Outlet Flow Path 36> As shown in Figure 6, 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 that 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 radially inward, 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.

[0037] According to the above configuration, the turbine-side inclined wall surface 73 is formed, allowing the turbine impeller 40 to be positioned 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, shortening the axial length of the first portion 51 reduces the load applied to the first portion 51 during operation of the supercharger 2. This improves the durability of the supercharger 2. Note that in the embodiment shown in Figure 6, the configuration that generates the first leak gas is not assumed. Specifically, the inner circumferential end face 79 of the first radially extending wall portion 70 and the sleeve 6 are not essential components of this disclosure. The above technical advantages can be obtained even without these components.

[0038] 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.

[0039] In some embodiments, nozzle vanes 55 are positioned between the outer circumferential surface 35b of the shroud and the turbine-side inclined wall surface 73. The nozzle vanes 55 may be either fixed or movable. With this configuration, the nozzle vanes 55 adjust the direction of the exhaust gas G3 flowing along the turbine-side inclined wall surface 73, thereby suppressing pressure loss when the exhaust gas G3 (see Figure 1) flows into the turbine impeller 40. More specifically, at least a portion of the exhaust gas G3 on the turbine-side inclined wall surface 73 flows toward the other side in the axial direction, then switches its flow direction in the axial direction and passes through the turbine impeller 40 on one side in the axial direction. A change in the flow direction of the exhaust gas G3 in the axial direction causes pressure loss in the flow of the exhaust gas G3, but the nozzle vanes 55 can reduce this pressure loss.

[0040] In some embodiments, the first wall surface 71 may further have an extending inner wall surface 74 that extends radially inward from the inner end 73a of the turbine-side inclined wall surface 73. The inclination angle of the extending inner wall surface 74 with respect to the radial direction is smaller than the inclination angle of the turbine-side inclined wall surface 73 with respect to the radial direction. In this example, the extending inner wall surface 74 extends parallel to the radial direction. The extending inner wall surface 74 is located on the other side of the back plate portion 45 of the turbine impeller 40 in the axial direction. With this configuration, the extending inner wall surface 74 guides the exhaust gas G3 flowing along the turbine-side inclined wall surface 73 to the turbine impeller 40, thereby suppressing pressure loss when the exhaust gas G3 flows into the turbine impeller 40.

[0041] Also, as described above, the first radially extending wall portion 70 is configured separately from the turbine housing 34 and the first compressor housing 33 (see FIG. 1). According to this configuration, since the constraints in manufacturing the first radially extending wall portion 70 can be reduced, the shape of the turbine-side inclined wall surface 73 can be made into a desired shape.

[0042] <First Compressor Impeller 10, First Compressor Housing 33> In some embodiments as shown in FIG. 6, the second wall surface 72 of the first radially extending wall portion 70 includes a compressor-side inclined wall surface 78 that forms 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 with respect to the radial direction so as to face one side in the axial direction as it goes toward the outer side in the radial direction. That is, each of the compressor-side inclined wall surface 78 and the housing-side inclined wall surface 29 is inclined with respect to the radial direction so as to face one side in the axial direction as it goes toward the outer side in the radial direction.

[0043] 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.

[0044] 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.

[0045] <Details of the supercharger 2> FIG. 7 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, a thrust bearing 59, and a motor 60.

[0046] The other-side journal bearing B2 supports the rotor 5 on the other side in the axial direction. The second compressor impeller 20 is disposed at a second portion 52 which is a portion of the rotor 5 protruding to the other side from the other-side journal bearing B2. The thrust bearing 59 is disposed at the second portion 52 between the other-side journal bearing B2 and the second compressor impeller 20.

[0047] The motor 60 includes a rotor 61, a stator 62, and a stator coil 63. The rotor 61 is disposed on the rotor 5 between the one-side journal bearing B1 and the other-side journal bearing B2. The stator 62 is disposed around the rotor 61. The stator coil 63 is disposed on the stator 62.

[0048] The supercharger 2 further includes a second compressor housing 25 that houses the second compressor impeller 20, and a motor housing 65 that houses the motor 60. 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 above-described 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. Since the energy possessed by the first leak gas flowing into the turbine impeller 40 increases, the turbine impeller 40 can recover more energy from the first leak gas.

[0050] The motor housing 65 has a coolant flow path 66 that extends circumferentially on the outer circumference of the stator 62, and an axial gas introduction passage 67 that extends axially on the outer circumference of the coolant flow path 66. A coolant, which may be water, flows through the coolant flow path 66. The axial gas introduction passage 67 is configured to guide the low-pressure compressed gas flowing through the second compressor flow path 28 to the first compressor impeller 10 as a supply gas.

[0051] According to the above configuration, the coolant flowing through the coolant passage 66 cools the low-pressure compressed gas flowing through the axial gas introduction passage 67 toward the first compressor impeller 10. As a result, the mass flow rate of the compressed gas G1 (see Figure 1) delivered by the first compressor impeller 10 increases, improving the compressor performance of the supercharger 2. In addition, the mass flow rate of the leak gas flowing into the turbine impeller 40 also increases, allowing the turbine impeller 40 to recover more energy from the first leak gas.

[0052] The motor housing 65 includes a other bearing housing 90 that houses the other journal bearing B2 and a thrust bearing 59. The other journal bearing B2 is supported by the other bearing housing 90.

[0053] The other bearing housing 90 defines a thrust bearing space Sb in which a thrust bearing 59 is located, and a other journal bearing space Sj in which a other journal bearing B2 is located. The thrust bearing space Sb and the other journal bearing space Sj are in communication with each other. Furthermore, the other bearing housing 90 has a radially extending gas passage 98 that communicates with the thrust bearing space Sb and extends radially. The radially extending gas passage 98 is open radially outward.

[0054] As previously described, a portion of the compressed gas G1 generated by the first compressor impeller 10 flows as leak gas to a location other than the supply line L1 (see Figure 1). The leak gas includes a second leak gas. The second leak gas passes sequentially through the first gap P1 between the first compressor housing 33 and one side journal bearing B1, and the motor gap Pm between the rotor 61 and the stator 62 (arrow A2). A portion of the second leak gas reaches the thrust bearing space Sb via the other side journal bearing space Sj. This second leak gas is discharged to the outside of the supercharger 2 from the radially extending gas flow path 98.

[0055] 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 a second leak gas. Subsequently, the second leak gas is discharged to the outside through the radially extending gas flow path 98. This allows the second leak gas to be used for cooling the thrust bearing 59.

[0056] 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.

[0057] A portion of the second 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 second 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.

[0058] <Heat Recovery System 1A(1)> Figure 8 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.

[0059] <Heat Recovery System 1B(1)> Figure 9 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.

[0060] <Summary> The contents described in the above-mentioned embodiments can be understood, for example, as follows:

[0061] 1) A supercharger (2) according to at least one embodiment of the present disclosure comprises: 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; and a first housing (30) that at least houses the turbine impeller and the first compressor impeller, the first housing having a first compressor-side passage (31) through which compressed gas (G1) compressed by the first compressor impeller flows and a turbine-side passage (38) through which exhaust gas (G3) flows toward the turbine impeller, wherein the first housing is The invention provides a shroud portion (35) which includes an inner circumferential surface (shroud inner circumferential surface 35a) that surrounds the turbine impeller and whose inner diameter increases towards one side of the rotor, and an outer circumferential surface (shroud outer circumferential surface 35b) formed on the opposite side of the inner circumferential surface and whose outer diameter decreases towards one side; and a first radially extending wall portion (70) formed between the first compressor-side flow path and the turbine-side flow path, wherein the first radially extending wall portion is a turbine-side inclined wall surface that is inclined with respect to the radial direction so as it moves towards the radially inward side of the rotor, and has a turbine-side inclined wall surface (73) which at least a portion overlaps the shroud portion in the radial direction.

[0062] According to the configuration described in 1) above, the turbine-side inclined wall surface is formed, allowing the turbine impeller to be positioned closer to the other side of the rotor than in conventional designs. This shortens the axial length of the rotor, resulting in a more compact supercharger.

[0063] 2) In some embodiments, the supercharger is as described in 1) above, wherein the turbine-side flow path has a turbine-side scroll flow path (37), and a portion of the turbine-side inclined wall surface is located radially outward with respect to the flow path centerline (Ls) of the turbine-side scroll flow path.

[0064] If the inclination angle of the turbine-side inclined wall is constant, the longer the radial length of the turbine-side inclined wall, the longer the axial length of the turbine-side inclined wall, and the shorter the axial length of the rotor can be. Therefore, according to the configuration in 2) above, the axial length of the rotor can be further shortened.

[0065] 3) In some embodiments, the supercharger described in 1) or 2) above further comprises a nozzle vane (55) disposed between the outer circumferential surface of the shroud portion and the turbine-side inclined wall surface of the first radially extending wall portion.

[0066] According to the configuration described in 3) above, the nozzle vanes adjust the direction of the exhaust gas (G3) flowing along the inclined wall surface on the turbine side, thereby suppressing pressure loss when the exhaust gas flows into the turbine impeller.

[0067] 4) In some embodiments, the supercharger is as described in any of 1) to 3) above, wherein the first radially extending wall portion further has an extending inner wall surface (74) that extends radially inward from the inner end (73a) of the turbine-side inclined wall surface, and the extending inner wall surface is located on the other side of the rotor than the back plate portion (45) of the turbine impeller.

[0068] According to the configuration described in 4) above, the extended inner wall surface guides the exhaust gas flowing along the turbine-side inclined wall surface to the turbine impeller, thereby suppressing pressure loss when the exhaust gas flows into the turbine impeller.

[0069] 5) In some embodiments, the supercharger is as described in any of 1) to 4) above, wherein the first housing further includes a turbine housing (34) for housing the turbine impeller and a first compressor housing (33) for housing the first compressor impeller, and the first radially extending wall portion is configured separately from the turbine housing and the first compressor housing, respectively.

[0070] According to the configuration in 5) above, the constraints on manufacturing the first radially extending wall can be reduced, making it possible to set the shape of the turbine-side inclined wall to a desired shape.

[0071] 6) In some embodiments, the supercharger is as described in any of 1) to 5) above, wherein the first compressor-side passage includes a diffuser passage (31d), and the diffuser passage extends inclined with respect to the radial direction so as it moves radially outward toward one side of the rotor.

[0072] According to the configuration described in 6) above, the inlet of the diffuser flow path can be moved to the other side of the rotor, allowing the first compressor impeller to be moved further to the other side than in the conventional configuration. This shortens the axial length of the rotor, making the supercharger even more compact.

[0073] 7) In some embodiments, the supercharger described in 6) above, wherein the first compressor impeller includes a plurality of first compressor blades (11) spaced apart in the circumferential direction, and the trailing edge (12) of each of the plurality of first compressor blades is tapered in diameter toward the hub side end (12h) of the first compressor impeller from the shroud side end (12s).

[0074] According to the configuration described in 7) above, the pressure loss when the compressed gas discharged from the trailing edge of the first compressor blade flows into the inclined diffuser passage can be reduced, thereby increasing the operating efficiency of the supercharger.

[0075] 8) In some embodiments, the supercharger is as described in any of 1) to 7) above, further comprising a one-sided journal bearing (B1) located on the other side of the rotor relative to the first compressor impeller, wherein the first portion (51) of the rotor on which the first compressor impeller and the turbine impeller are located is cantilevered by the one-sided journal bearing.

[0076] According to the configuration described in 8) above, the axial length of the first part can be shortened, thereby reducing the load applied to the first part when the turbocharger is in operation. As a result, the durability of the turbocharger can be improved.

[0077] 9) In some embodiments, a supercharger according to any one of 1) to 8) above, wherein the turbine impeller includes a plurality of turbine blades spaced apart in the circumferential direction, and the turbine impeller is a diagonal flow turbine impeller in which the leading edge of each of the plurality of turbine blades decreases in diameter from the shroud side toward the hub side.

[0078] According to the configuration described in 9) above, the leading edge of the turbine impeller extends inclined with respect to the axial direction, making it possible to make the turbine impeller more compact.

[0079] 10) In some embodiments, a supercharger according to any of 1) to 9) above further comprises: a second compressor impeller (20) disposed on the other side of the rotor; a motor (60) including a rotor (61) disposed on the rotor between the first compressor impeller and the second compressor impeller; and a stator (62) disposed around the rotor, wherein the low-pressure compressed gas compressed by the second compressor impeller is delivered to the first compressor impeller.

[0080] According to the configuration described in 10) above, the pressure of the compressed gas generated by the first compressor impeller can be increased.

[0081] 11) In some embodiments, the supercharger described in 10) further comprises a motor housing (65) for housing the motor, the motor housing having a coolant flow path (66) extending circumferentially on the outer circumference side of the stator, and an axial gas introduction path (67) extending axially on the outer circumference side of the rotor with respect to the coolant flow path, for guiding the low-pressure compressed gas compressed by the second compressor impeller to the first compressor impeller.

[0082] According to the configuration described in 11) above, the coolant flowing through the coolant passage cools the low-pressure compressed gas that is guided to the first compressor impeller by the axial gas introduction passage. As a result, the mass flow rate of the compressed gas delivered by the first compressor impeller increases, thereby improving the compressor function of the supercharger.

[0083] 12) In some embodiments, the supercharger described in 10) or 11) 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 a thrust bearing space (Sb) 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.

[0084] According to the configuration described in 12) 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.

[0085] 13) In some embodiments, the supercharger described in 12) above comprises: a journal bearing (B2) disposed on the rotor between the thrust bearing and the rotor and housed in the other bearing housing; and a motor housing (65) housing the motor, wherein the other bearing housing includes: a cylindrical wall portion (91) surrounding the journal bearing; and a second radially extending wall portion (92) extending radially outward from the cylindrical wall portion, wherein an axial through passage (97) is formed in the second radially extending wall portion, which penetrates the rotor in the axial direction and connects the inner space (65S) of the motor housing with the thrust bearing space.

[0086] According to the configuration described in 13) above, the leak gas from the compressed gas compressed by the first compressor impeller that flows into the motor housing space also flows into the thrust bearing space via the axial through passage. Therefore, the cooling of the thrust bearing can be promoted.

[0087] 14) 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 any of 1) to 11) above; and a heat recovery device configured to recover heat from the 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 as exhaust gas into the turbine-side flow path of the first housing.

[0088] According to the configuration in 14) above, the same technical advantages as in 1) above can be obtained.

[0089] 15) In some embodiments, the heat recovery system is as described in 14) 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.

[0090] According to the configuration described in item 15) above, electricity can be generated using compressed gas as an oxidizing gas.

[0091] 16) In some embodiments, the heat recovery system is as described in 14) 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 (100), 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-side flow path of the first housing.

[0092] According to the configuration described in item 16) above, compressed gas can be used as a refrigerant gas to cool the object to be cooled.

[0093] 1A, 1B(1): Heat recovery system 2: Supercharger 3A, 3B(3): Heat recovery device 5: Rotor 5c: Shaft 6: Sleeve 6a: Outer surface of sleeve 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: Inner surface of shroud 35b: Outer surface of shroud 36 : Turbine outlet passage 37 : Turbine side scroll passage 38 : Turbine side passage 40 : Turbine impeller 41 : Hub body 42 : Hub surface 43 : Back surface 44 : Turbine blade 45 : Back plate section 46 : Leading edge 46h : Hub side end 46s : Shroud side end 47 : Boss section 48 : Scallop 49 : Concave surface 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 70A, 70B (70) : First radially extending wall section 71 : First wall surface 72: Second wall surface 73: Turbine side inclined wall surface 73a: Inner end 74: Extending inner wall surface 75: Axial hole 76: Installation body 77: Fin 78: Compressor side inclined wall surface 79: Inner circumferential end surface 80: Gas intake passage 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 A1, A2, A3,R: Arrow B1: One-sided journal bearing B2: Other-sided journal bearing G1: Compressed gas G3: Exhaust gas Gs: Small gap L1: Supply line L2: Discharge line Ls: Flow path centerline P1: First gap Pm: Motor gap Sb: Thrust bearing space Sj: Other-sided journal bearing space

Claims

1. 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; and a first housing that houses at least the turbine impeller and the first compressor impeller, the first housing having a first compressor-side passage for compressed gas compressed by the first compressor impeller to flow and a turbine-side passage for exhaust gas to flow toward the turbine impeller, wherein the first housing includes a shroud portion having an inner circumferential surface that surrounds the turbine impeller and whose inner diameter increases toward the one side of the rotor, and an outer circumferential surface formed on the opposite side of the inner circumferential surface and whose outer diameter decreases toward the one side, and a first radially extending wall portion formed between the first compressor-side passage and the turbine-side passage, The first radially extending wall portion is a turbine-side inclined wall surface that is inclined with respect to the radial direction so as it moves radially inward toward the other side of the rotor, and at least a portion of the turbine-side inclined wall surface overlaps radially with the shroud portion.

2. The turbocharger according to claim 1, wherein the turbine-side flow path has a turbine-side scroll flow path, and a portion of the turbine-side inclined wall surface is located radially outward with respect to the flow path centerline of the turbine-side scroll flow path.

3. The supercharger according to claim 1 or 2, further comprising nozzle vanes disposed between the outer circumferential surface of the shroud portion and the turbine-side inclined wall surface of the first radially extending wall portion.

4. The supercharger according to claim 1 or 2, wherein the first radially extending wall portion further has an extending inner wall surface that extends radially inward from the inner end of the turbine-side inclined wall surface, and the extending inner wall surface is located on the other side of the rotor than the back plate portion of the turbine impeller.

5. The supercharger according to claim 1 or 2, wherein the first housing further includes a turbine housing for housing the turbine impeller and a first compressor housing for housing the first compressor impeller, and the first radially extending wall portion is configured separately from the turbine housing and the first compressor housing, respectively.

6. The supercharger according to claim 1 or 2, wherein the first compressor-side passage includes a diffuser passage, and the diffuser passage extends inclined with respect to the radial direction so as it moves radially outward, it moves toward one side of the rotor.

7. The supercharger according to claim 6, wherein the first compressor impeller includes a plurality of first compressor blades arranged at intervals in the circumferential direction, and the trailing edge of each of the plurality of first compressor blades is smaller in diameter towards the hub side of the first compressor impeller than towards the shroud side.

8. The supercharger according to claim 1 or 2, further comprising a one-sided journal bearing disposed on the other side of the rotor relative to the first compressor impeller, wherein the first portion of the rotor on which the first compressor impeller and the turbine impeller are disposed is cantilevered by the one-sided journal bearing.

9. The supercharger according to claim 1 or 2, wherein the turbine impeller includes a plurality of turbine blades arranged at intervals in the circumferential direction, and the turbine impeller is a diagonal flow turbine impeller in which the leading edge of each of the plurality of turbine blades decreases in diameter from the shroud side toward the hub side.

10. A supercharger according to claim 1 or 2, further comprising: a second compressor impeller disposed on the other side of the rotor; a motor including a rotor disposed on the rotor between the first compressor impeller and the second compressor impeller; and a stator disposed around the rotor, wherein a low-pressure compressed gas compressed by the second compressor impeller is delivered to the first compressor impeller.

11. The supercharger according to claim 10, further comprising a motor housing for housing the motor, wherein the motor housing is formed of a coolant flow path extending circumferentially on the outer circumference side with respect to the stator, and an axial gas introduction path extending axially on the outer circumference side with respect to the coolant flow path, the axial gas introduction path for guiding the low-pressure compressed gas compressed by the second compressor impeller to the first compressor impeller.

12. The supercharger according to claim 10, 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 flow path formed therein for guiding leak gas, which is the 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.

13. A supercharger according to claim 12, comprising: a journal bearing disposed in the rotor between the thrust bearing and the rotor and housed in the other bearing housing; and a motor housing housing the motor, wherein the other bearing housing includes a cylindrical wall portion surrounding the journal bearing and a second radially extending wall portion extending radially outward from the cylindrical wall portion, and the second radially extending wall portion has an axial through passage that penetrates the rotor in the axial direction and connects the inner space of the motor housing with the thrust bearing space.

14. A heat recovery system comprising: a supercharger according to claim 1 or 2; and a heat recovery device configured to recover heat from the 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-side flow path of the first housing as exhaust gas.

15. The heat recovery system according to claim 14, 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.

16. The heat recovery system according to claim 14, 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-side flow path of the first housing.

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