turbocharger turbine wheel

Abstract

A turbocharger turbine wheel can include a hub including an axis of rotation, a back disk, and a nose, wherein the axis of rotation defines an axial coordinate (z) in a cylindrical coordinate system including a radial coordinate (r) and a azimuthal coordinate ( ) along an intended direction of rotation about the axis of rotation; and blades extending outwardly from the hub, wherein each of the blades includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, wherein the hub profile includes a global maximum radius and a global minimum radius, and wherein, between the global maximum radius and the global minimum radius, in an axial direction from the back disk to the nose, the hub profile includes a local minimum radius at a first axial coordinate location and a local maximum radius at a second axial coordinate location.

Description

Technical Field

[0001] The topics disclosed in this article generally relate to turbocharger turbine impellers used in internal combustion engines. Background Technology

[0002] A turbocharger may include a rotating assembly comprising a turbine impeller and a compressor impeller connected to each other via a shaft. For example, the turbine impeller may be welded or otherwise attached to the shaft to form a shaft and impeller assembly (SWA), and the compressor impeller may be fitted to the free end of the shaft. As an example, the shaft attached to one or more bladed impellers may be supported by one or more bearings housed in bearing housings that may form a central housing rotating assembly (CHRA). During turbocharger operation, the SWA may be expected to rotate at speeds exceeding 200,000 rpm, depending on factors such as the size of various components. Attached Figure Description

[0003] A more complete understanding of the various methods, apparatuses, components, systems, arrangements, etc., and their equivalents described herein can be obtained by referring to the examples shown in the accompanying drawings and by referring to the following specific embodiments, wherein:

[0004] Figure 1 It is a diagram of a turbocharger, an internal combustion engine, and a controller;

[0005] Figure 2 This is a cross-sectional view of an example turbocharger;

[0006] Figure 3 This is a side view of an example turbocharger;

[0007] Figure 4 These are perspective views and enlarged views of an example shaft and impeller assembly (SWA);

[0008] Figure 5 This is a projected view of an example of turbine impeller blades;

[0009] Figure 6A , Figure 6B and Figure 6C These are a series of views of an example turbine impeller;

[0010] Figure 7 This is a view of a portion of an example of a turbine impeller;

[0011] Figure 8 This is a view of a portion of an example of a turbine impeller;

[0012] Figure 9 This is a side view of a portion of an example of a turbine impeller;

[0013] Figure 10 This is a side view of a portion of an example of a turbine impeller;

[0014] Figure 11 This is a radial view of a portion of an example of a turbine impeller; and

[0015] Figure 12 This is an exemplary diagram illustrating the relationship between turbine efficiency and turbine speed. Detailed Implementation

[0016] The following text describes examples of turbocharged engine systems, followed by various examples of parts, components, methods, and so on.

[0017] Turbochargers are frequently used to increase the output of internal combustion engines. (Reference) Figure 1 As an example, system 100 may include an internal combustion engine 110 and a turbocharger 120. Figure 1 As shown, system 100 may be part of vehicle 101, wherein system 100 is housed in the engine compartment and connected to exhaust duct 103, which directs exhaust gas to exhaust outlet 109, for example, located behind passenger compartment 105. Figure 1 In one example, a processing unit 107 may be provided to process exhaust gas (e.g., reduce emissions via catalytic conversion of molecules, etc.).

[0018] like Figure 1 As shown, the internal combustion engine 110 includes an engine block 118 that houses one or more combustion chambers operably driven by a shaft 112 (e.g., via a piston), and an intake port 114 that provides a flow path for air reaching the engine block 118 and an exhaust port 116 that provides a flow path for exhaust from the engine block 118.

[0019] The turbocharger 120 can be used to extract energy from exhaust gas and provide that energy to intake air, which can then combine with fuel to form combustion gases. For example... Figure 1 As shown, the turbocharger 120 includes an air inlet 134, a shaft 122, a compressor housing assembly 124 for a compressor impeller 125, a turbine housing assembly 126 for a turbine impeller 127, another housing assembly 128, and an exhaust outlet 136. The housing assembly 128 may be referred to as the central housing assembly because it is located between the compressor housing assembly 124 and the turbine housing assembly 126.

[0020] exist Figure 1In the turbocharger 120, the shaft 122 may be a shaft assembly comprising various components (e.g., consider a shaft and impeller assembly (SWA) in which the turbine impeller 127 is welded to the shaft 122, etc.). As an example, the shaft 122 may be rotatably supported by a bearing system (e.g., journal bearings, rolling element bearings, etc.) disposed in the housing assembly 128 (e.g., in bores defined by one or more bore walls), such that rotation of the turbine impeller 127 causes rotation of the compressor impeller 125 (e.g., because it is rotatably coupled via the shaft 122). As an example, the central housing rotating assembly (CHRA) may include the compressor impeller 125, the turbine impeller 127, the shaft 122, the housing assembly 128, and various other components (e.g., compressor side plates disposed at an axial position between the compressor impeller 125 and the housing assembly 128).

[0021] exist Figure 1 In the example, the variable geometry component 129 is shown partially disposed between the housing assembly 128 and the housing assembly 126. This variable geometry component may include guide vanes or other components to change the geometry of the passageway leading to the turbine impeller space in the turbine housing assembly 126. As an example, a variable geometry compressor assembly may be provided.

[0022] exist Figure 1 In the example, the exhaust valve (or simply exhaust valve) 135 is positioned near the exhaust inlet of the turbine housing assembly 126. The exhaust valve 135 can be controlled to allow at least some of the exhaust gas from the exhaust port 116 to bypass the turbine impeller 127. Various exhaust valves, exhaust valve components, etc., can be applied to conventional fixed-nozzle turbines, fixed-guide-vane nozzle turbines, variable-nozzle turbines, twin-scroll turbochargers, etc. As an example, the exhaust valve can be an internal exhaust valve (e.g., at least partially inside the turbine housing). As an example, the exhaust valve can be an external exhaust valve (e.g., operatively coupled to a duct in fluid communication with the turbine housing).

[0023] exist Figure 1 The example also shows an exhaust gas recirculation (EGR) duct 115, which may optionally be provided with one or more valves 117 to allow exhaust gas to flow to a location upstream of the compressor impeller 125.

[0024] Figure 1An exemplary arrangement 150 for directing exhaust gas to an exhaust turbine housing assembly 152 and another exemplary arrangement 170 for directing exhaust gas to an exhaust turbine housing assembly 172 are also shown. In arrangement 150, a passage 156 is included within the cylinder head 154 to guide exhaust gas from the cylinder to the turbine housing assembly 152; while in arrangement 170, a manifold 176 enables the installation of the turbine housing assembly 172, for example, without any separate intermediate length of exhaust pipe. In exemplary arrangements 150 and 170, turbine housing assemblies 152 and 172 can be configured for use with wastegates, variable geometry assemblies, etc.

[0025] exist Figure 1 In this document, an example of controller 190 is shown including one or more processors 192, memory 194, and one or more interfaces 196. This controller may include circuitry, such as that of an engine control unit (ECU). As described herein, various methods or techniques may optionally be implemented, for example, by combining the controller with control logic. The control logic may depend on one or more engine operating conditions (e.g., turbo rpm, engine rpm, temperature, load, lubricant, cooling, etc.). For example, sensors may transmit information to controller 190 via one or more interfaces 196. The control logic may depend on this information, and subsequently, controller 190 may output control signals to control engine operation. Controller 190 may be configured to control lubricant flow, temperature, variable geometry components (e.g., variable geometry compressors or turbines), exhaust valves (e.g., via actuators), electric motors, or one or more other components associated with the engine, turbocharger (or multiple turbochargers), etc. As an example, turbocharger 120 may include one or more actuators and / or one or more sensors 198, which may be coupled, for example, to one or more interfaces 196 of controller 190. As an example, the exhaust valve 135 can be controlled by a controller that includes an actuator that responds to electrical signals, pressure signals, etc. As an example, the actuator for the exhaust valve can be, for example, a mechanical actuator that can operate without electricity (e.g., consider a mechanical actuator configured to respond to a pressure signal supplied via a conduit).

[0026] Figure 2An example of a turbocharger 200 is shown, which includes a turbine assembly 201, a compressor assembly 202, and a central housing 203. The turbine assembly 201 includes a turbine housing 204 shaped to receive a turbine impeller 205, and the compressor assembly 202 includes a compressor housing 206 shaped to receive a compressor impeller 207. As shown, a shaft 208 operatively couples the turbine impeller 205 and the compressor impeller 207 when supported by one or more bearings 215 and 216 in a through-hole in the central housing 203.

[0027] like Figure 2 As shown, the turbine housing 204 may include an exhaust inlet 210 and an exhaust outlet 211, wherein the volute 212 is at least partially defined by the turbine housing 204. The volute 212 may be referred to as a spiral, and its cross-sectional diameter decreases as it spirals inward toward the turbine impeller space that houses the turbine impeller 205.

[0028] like Figure 2 As shown, the compressor housing 206 may include an air inlet 213 and an air outlet 211, wherein a volute 214 is at least partially defined by the compressor housing 206. The volute 214 may be referred to as a spiral, and its cross-sectional diameter increases as it spirals outward from the compressor impeller space housing the compressor impeller 207.

[0029] A backplate 220 is disposed between the compressor housing 206 and the central housing 203, and includes a hole 221 for receiving a thrust ring 222, which abuts against the base end 223 of the compressor impeller 207. As shown, the thrust ring 222 may include a radially outwardly extending lubricant retainer ring 225, which can help reduce unwanted lubricant flow (e.g., flow into the compressor impeller space, etc.).

[0030] The central housing 203 includes various lubricant features, such as a lubricant inlet 217, a lubricant orifice 218, a lubricant nozzle 219, and a lubricant outlet 229. As shown, lubricant can be supplied at the lubricant inlet 217 to flow to the lubricant orifice 218 and the lubricant nozzle 219, the lubricant nozzle 219 including a compressor-side nozzle for directing lubricant to bearing 215 and a turbine-side nozzle for directing lubricant to bearing 216. When the turbine impeller 205 is driven by the exhaust flow through the turbine housing 204, the lubricant can carry away heat from bearings 215 and 216 as they rotatably support the shaft 208.

[0031] like Figure 2As shown in the example, compressor housing 206 can be clipped to back plate 220 via clip 231, back plate 220 can be bolted to center housing 203 via one or more bolts 232, and center housing 203 can be bolted to turbine housing 204 via one or more bolts 233; note that various other techniques can be used to couple the components to form a turbocharger.

[0032] exist Figure 2 In the examples, one or more of the casings 203, 204, and 206 can be cast. For example, turbine casing 204 can be cast from iron, steel, nickel alloys, etc. As an example, consider a nickel-resistant cast iron alloy with a sufficient amount of nickel to produce an austenitic structure. For example, consider nickel present in amounts from about 12 to about 40 wt%. As an example, increasing the amount of nickel can achieve a reduced coefficient of thermal expansion (e.g., consider a minimum of about 35 wt%). However, the increased nickel content may increase the cost of the nickel-resistant material; note that over a wide range of nickel contents (e.g., about 7.3 to 7.6 g / cm³), the density tends to be relatively constant. The density of nickel-resistant materials tends to be about 5% higher than that of gray cast iron and about 15% lower than that of cast bronze alloys. Regarding machinability, nickel-resistant materials tend to be better than cast steel; note that increased chromium content tends to reduce machinability due to the increased amount of hard carbides. Compared to stainless steel (e.g., with a density of approximately 8 g / cm³), nickel-resistant materials may be less expensive and lighter (e.g., with a lower density).

[0033] Nickel-resistant materials often exhibit suitable high-temperature properties, which may be rated to exceed 480 degrees Celsius (900 degrees Fahrenheit). Nickel-resistant materials may be suitable for turbochargers in diesel and gasoline internal combustion engines. As an example, a diesel engine may have exhaust that can be maintained at approximately 860 degrees Celsius, and as an example, a gasoline engine may have exhaust that can be maintained at approximately 1050 degrees Celsius. Such exhaust can be received by a turbine assembly, which includes a turbine housing made of a suitable material.

[0034] As shown in the figure, compared with the compressor housing 206 and the central housing 203, the turbine housing 204 can be a relatively large component, so that the mass of the turbine housing 204 significantly affects the mass of the turbocharger 200.

[0035] exist Figure 2In the example, various components of the turbocharger 200 can be defined relative to a cylindrical coordinate system, which includes a z-axis centered on a through-hole in the central housing 203. This z-axis can coincide with the axis of rotation of a rotating assembly including a turbine impeller 205, a compressor impeller 207, and a shaft 208. As mentioned, the turbine impeller can be welded to the shaft to form a shaft and impeller assembly (SWA), and the compressor impeller can be threaded onto an end of the shaft (e.g., a "holeless" compressor impeller) or have a through-hole receiving the free end of the shaft, wherein a nut or other suitable component is used to secure the compressor impeller to the shaft. Figure 2 In the example, turbine impeller 205 is welded to shaft 208, and nut 235 is used to secure compressor impeller 207 to shaft 208, and thus to turbine impeller 205.

[0036] exist Figure 2 In the example, a gap exists between the blades 254 extending from the hub 252 of the turbine impeller 205 and the shroud portion 240 of the turbine housing 204. As shown in the cross-sectional view, the shroud portion 240 is "J"-shaped, which may define a rotating body having an annular ridge portion 242 and a cylindrical portion 244. As shown, the annular ridge portion 242 may define a nozzle at the inlet section of the turbine impeller 205 for exhaust gas flowing from the volute 212 into the turbine impeller space, which may be defined by a leading edge, wherein each of the blades 254 includes a leading edge (LE). As shown, the turbine impeller 205 also includes an outlet section, wherein each of the blades 254 includes a trailing edge (TE). During operation, exhaust gas flows from the volute 212 to the leading edge of the blade 254 via a nozzle partially defined by the annular ridge portion 242 of the shroud portion 240, flows along a channel defined by the adjacent blades 254 of the turbine impeller 205 between the hub 252 and the cylindrical portion 244 of the shroud portion 240, and then flows to the trailing edge of the blade 254, where the exhaust gas is confined by a larger diameter cylindrical wall 272, a slightly conical wall 274, and an even larger diameter cylindrical wall 276. Figure 2 As shown, the cylindrical wall 276 may be defined by a portion of the turbine housing 204, which includes fittings such as annular ridges 282 for securing exhaust ducts to the turbine housing 204. Such exhaust ducts may be in fluid communication with one or more other components, such as an exhaust treatment unit, a muffler, another turbocharger, etc. Regarding the exhaust inlet 210 of the turbine housing 204, it may also be shaped to couple to one or more exhaust ducts, such as, for example, an exhaust manifold, an exhaust crosspipe, another turbine housing (e.g., for a multi-stage turbocharger arrangement), etc.

[0037] like Figure 2As shown, the turbine housing 204 serves a variety of functions through its structural features and shape; however, these structural features may affect the quality of the turbocharger.

[0038] As an example, the weight of a turbocharger can range from approximately 4 kg (e.g., 8.8 lbs) to approximately 40 kg (e.g., 88 lbs) or more.

[0039] As mentioned, the turbocharger can be defined relative to a cylindrical coordinate system, where the z-axis can be along its length. Figure 2 In the example, the length of the turbine housing 204 exceeds 50% of the total length. When installed in the engine compartment of a vehicle, the total length or size of the turbocharger may be a factor due to design limitations.

[0040] As an example, a turbocharger may include a turbine assembly having specific features that can improve the performance of the turbocharger and reduce its mass and / or size. For example, consider a turbine impeller including a tapered region disposed between the leading and trailing edges of the turbine impeller blades. Figure 2 In this design, the shroud portion 240 and the blades 254 have a cylindrical shape, identified by the cylindrical portion 244. In contrast, an exemplary turbine assembly may include a shroud portion of the turbine housing and blades of the turbine impeller, which include a tapered shape that achieves a reduction in the axial length of the turbine impeller or a smaller axial distance between the tip of the leading edge and the tip of the trailing edge of the blade. By incorporating a tapered turbine impeller, the turbine housing can be made smaller, and thus helps to reduce the length and / or mass of the turbocharger. For vehicles including one or more such turbochargers, this can translate into several benefits (e.g., smaller mass, less cooling thermal mass, faster cooling, greater flexibility in arrangement within the engine compartment, smaller engine compartment, etc.).

[0041] Alternatively, performance can be improved by using blades that include tapered sections, wherein the turbine casing may include shroud sections that include similar matching tapered sections. As performance increases, several benefits can be achieved, for example, regarding the balance between size, mass, and performance.

[0042] As an example, turbine impellers with tapered sections can offer several benefits that can lead to a reduction in the overall size and mass of the turbine casing. For instance, consider reducing the size of the volute, which allows for a reduction in material requirements. Figure 2 As shown, the volute 212 is defined by the turbine housing 204, particularly by an annular wall having a "C"-shaped cross-section. As an example, reducing the outer diameter of the turbine impeller can achieve a reduction in the maximum radius of the turbine housing (e.g., to form a volute with a maximum radius).

[0043] Figure 2 The turbocharger 200 can be cooled by one or more media, such as lubricant (e.g., oil), water (e.g., radiator fluid, etc.) and air (e.g., via an environment having ambient air or vehicle engine compartment air).

[0044] There are some trade-offs regarding lubricant cooling (e.g., oils, whether natural or synthetic, etc.). For example, if a carbonaceous lubricant reaches excessively high temperatures for too long (e.g., considering time-temperature dependence), carbonization (e.g., also known as coking or “coking”) can occur. Coking can exacerbate heat generation and heat retention through any of a number of mechanisms, and over time, coke deposits can shorten the life of a lubricated bearing system. As an example, coke deposits can lead to reduced heat transfer and increased heat generation, which can cause bearing system failure. To overcome coking, turbochargers can be configured to improve lubricant flow. For example, a pump can pressurize the lubricant to increase the flow rate, thereby reducing the residence time of the lubricant in high-temperature regions. However, increased lubricant pressure can exacerbate various types of lubricant leakage problems. For example, increased lubricant pressure in a bearing system can cause lubricant to leak into the exhaust turbine, air compressor, or both. Escape via the exhaust turbine can result in observable levels of smoke, while escape via the air compressor can cause lubricant to enter the intercooler, combustion chamber (e.g., combustion cylinder), and so on.

[0045] Regarding the temperatures experienced during operation, this likely depends on the temperature of the exhaust gas flowing to the turbocharger's exhaust turbine, which in turn depends on whether the internal combustion engine uses gasoline or diesel fuel (e.g., as mentioned, a diesel engine can have exhaust gas at around 860 degrees Celsius, and a gasoline engine can have exhaust gas at around 1050 degrees Celsius). Similarly, regarding temperature, consider... Figure 1 Exemplary arrangements 150 and 170, wherein turbine housing assemblies 152 and 172 are in close proximity to the combustion cylinder, which may cause turbine housing assemblies 152 and 172 to experience higher exhaust temperatures and / or higher ambient temperatures.

[0046] Figure 3 An example of a turbocharger 300 is shown, which includes a compressor assembly 340 with a compressor housing for a compressor impeller, a turbine assembly 360 with a turbine housing for a turbine impeller, a central housing 380 for bearings, a bearing or bearing assembly that rotatably supports the shaft and impeller assembly (SWA), and an actuator 350 with a linkage mechanism 354 that reaches a control arm assembly 358 for an exhaust valve for the turbine assembly 360. The turbocharger 300 may include... Figure 2 One or more components are shown. In Figure 3In the view, the exhaust inlet of turbine assembly 360 is not visible because it is on the opposite side. The general flow direction of air or exhaust is indicated by arrows. Actuator 350 is shown as being mounted to compressor assembly 340, which helps reduce the temperature experienced by actuator 350 (e.g., compared to mounting the actuator on the turbine housing). Turbocharger 300 can be a vehicle (such as, for example, Figure 1 As part of vehicle 101. As an example, turbine assembly 360 may optionally be arranged such as in Figure 1 In one of the exemplary arrangements 150 or 170.

[0047] Figure 4 A perspective view of the shaft and impeller assembly (SWA) 400 is shown. As shown, the SWA 400 includes a shaft 420, a sealing portion 440, and a turbine impeller 460, wherein the turbine impeller 460 includes a nose 470, a back disk 480, and blades 490. The turbine impeller 460 may be a single integral piece of material and is referred to as a single component or monolithic piece. A portion of the turbine impeller 460 may be referred to as a hub 465. For example, the back disk 480 may be a portion of the hub 465 from which the blades 490 extend. The hub 465 may include the back disk 480 and a nose 470 including a nose end 475, and extends the length of the turbine impeller, as indicated by the axial length ztw measured along the z-axis of rotation of the SWA 400.

[0048] As an example, the sealing portion 440 may be formed partly by the turbine impeller 460 and partly by the shaft 420; it may be formed by the shaft 420 or by the turbine impeller 460. As an example, the sealing portion 440 may be at least partially formed by the shaft 420. The sealing portion 440 may be defined by an outer radius. Figure 2 In the diagram, a sealing portion is shown at least partially disposed within a turbine side bore opening of the central housing 203, wherein one or more sealing elements (e.g., rings, etc.) are disposed within one or more annular grooves in the sealing portion and / or the turbine side bore wall defining the turbine side bore opening. Reference Figure 2 The sealing portion can form one or more seals between the lubricant area of ​​the central housing 203 and the exhaust area where the turbine impeller 205 is housed.

[0049] like Figure 4 As shown, SWA 400 may include a shoulder or a portion that gradually decreases in size from turbine impeller 460 toward shaft 420. For example, the shoulder may gradually decrease from the outer surface of shaft joint portion 450 to outer surface 455, the radius of which may be equal to or approximately equal to the radius of sealing portion 440. Shaft joint portion 450 may include a surface that serves as an annular axial face, which may form part of the shoulder.

[0050] As an example, shaft joint portion 450 may include a shaft joint surface that can be partially defined by the shaft joint radius. For example, consider a shaft joint surface that can be used to attach a shaft to a turbine impeller (e.g., via welding, etc.). In such an example, the turbine impeller shaft joint surface may be a mating surface that mates with the turbine impeller joint surface of the shaft, whereby the two surfaces can be brought close to or directly contacted and joined (e.g., via welding). As an example, the shaft joint surface may be an annular surface that can be welded to the surface of the shaft to form a SWA (e.g., forming one or more welds).

[0051] SWA 400 may include several dimensions, such as, for example, the axial dimension zc of the compressor impeller portion, which may include one or more guide surfaces, a set of threads, etc., and the bearing portion zj, which may include one or more journal surfaces (e.g., compressor-side journal surface and turbine-side journal surface, etc.).

[0052] like Figure 4 As shown, the sealing portion 440 may include one or more annular grooves that can be configured to receive one or more sealing elements (e.g., one or more sealing rings). As illustrated, the sealing portion 440 may be partially defined by an axial dimension zsp. As an example, the sealing element may be an open ring, such as, for example, a piston ring. As mentioned, the SWA can be formed by welding a shaft to a turbine impeller, such that the resulting SWA has a shaft and turbine impeller arranged and fixed along a common axis of rotation.

[0053] Figure 4 The diagram shows an enlarged perspective view of a portion of the SWA 400, specifically the turbine impeller 460. As an example, the turbine impeller can be defined using a diameter, which may be a circle circumscribed with the features of the turbine impeller. For example, in the case where the turbine impeller comprises an odd number of blades, the diameter as a line may not be drawn from the leading edge of one blade to the leading edge of another. In such an example, the diameter may be defined via a circle circumscribed with the leading edges of the blades, or, for example, mathematically defined as twice the radius. The turbine impeller can be defined by an inlet section diameter (e.g., associated with exhaust flow) and an outlet section diameter (e.g., associated with exhaust flow). As an example, the inlet section diameter may exceed the outlet section diameter. As an example, the turbine impeller can be defined using its inlet section diameter and outlet section diameter. When referring to a diameter, it may refer to the diameter of a circle that can be drawn with respect to the features of the turbine impeller. As an example, the turbine impeller can be defined using axial, radial, and azimuth coordinates (e.g., r, z, and). It is confined in the cylindrical coordinate system of ).

[0054] As an example, the balancing process can alter one or more dimensions of the turbine impeller, for instance, by removing material. Consider, for example, removing material from the nose 470 of the turbine impeller 460 of the SWA 400. As shown, the nose 470 has an outer diameter smaller than the outer diameter of the backplate 480. Another option could be to remove material from the backplate 480. As an example, material could be removed from the shaft joint portion 450. In such an example, material removal likely has minimal impact on the backplate 480's capability with respect to its supporting blades 490.

[0055] like Figure 4 As shown in the example, the exhaust turbocharger turbine impeller 460 may include: a hub 465, the hub 465 including a nose 470, a back plate 480, a shaft joint portion 450 (e.g., as part of the back plate 480), and a rotation axis (z-axis); blades 490 extending from the hub 465 to define an exhaust flow passage, wherein each of the blades 490 includes a leading edge (LE), a trailing edge (TE), a hub profile, a shroud profile defined by a shroud edge (SE), a pressure side (PS), and a suction side (SS); wherein the back plate 480 includes an outer circumferential radius measured from the rotation axis of the hub 465 and an intermediate radius measured from the rotation axis of the hub 465 at the outer periphery of the shaft joint portion 450.

[0056] Regarding the shaft connector portion 450, it is shown as generally cylindrical. As an example, the backplate 480 may be defined as the lower portion of the hub 465, which includes at least a portion of the shaft connector portion 450 and extends outward to the maximum outer perimeter of the backplate 480.

[0057] As explained, the shaft joint portion 450 may be coupled to the sealing portion 440, which may be a component of the shaft 420. As an example, the sealing portion 440 may be welded to the shaft joint portion 450 to form a welded joint that permanently connects the shaft 420 and the turbine impeller 460 to form a shaft and impeller assembly (SWA) 400.

[0058] As an example, the shaft can be made of the same material as the turbine impeller or a different material. In the case of different materials, the materials can typically be welded to form a SWA (Surface Mount Alloy). As an example, the compressor impeller can be made of a material with a lower specific gravity than the turbine impeller material. Generally, the compressor impeller experiences operating temperatures lower than those of the turbine impeller. As an example, the turbine impeller can be made of a nickel alloy. For example, consider NiCrFe-based alloys (e.g., Hastelloy). TM Materials, INCONEL TMMaterials, etc.) or another alloy. In contrast, compressor impellers can be made of lighter materials, such as, for example, aluminum or aluminum alloys. Turbine impeller materials can have a specific gravity twice or more than twice that of aluminum (aluminum is approximately 2.7, compared to INCONEL). TM Approximately 8.4 of 625 material.

[0059] The rotating assembly may have components constituting the rotating assembly (e.g., see...). Figure 2 The mass is defined by the sum of the individual masses of the rotating components (including turbine impeller 205, compressor impeller 207, and shaft 208). As mentioned, the exhaust flow arriving at the exhaust turbine housed in the turbine casing can be the drive for the rotation of the rotating components, where mass and other factors can determine the amount of exhaust that must flow before rotation begins.

[0060] Figure 5 An example representation of turbine impeller blade 590 relative to an r, z coordinate system is shown, where r is the radial coordinate and z is the axial coordinate, with the z-axis aligned with the turbine impeller's axis of rotation. Figure 5 As shown in the example, blade 590 includes various blade features such as a leading edge 591 (or inlet section edge), a trailing edge 599 (or outlet section edge), a back disk point 592 of the leading edge 591, a tip point 593 of the leading edge 591, a hub point 594 of the trailing edge 599, a tip point 595 of the trailing edge 599, a hub profile 596 extending from the leading edge 591 to the trailing edge 599, and a shroud edge 598 (e.g., a shroud profile) extending from the leading edge 591 to the trailing edge 599. As shown, the r-axis is orthogonal to the z-axis and is located at the z-coordinate corresponding to the back disk point 592 of the leading edge 591. Various points of blade 590 can be described using an r, z coordinate system. Figure 5 In this context, blade 590 can be defined with respect to radial and axial coordinates. As an example, a polar diagram can be used to provide additional information defining blade 590. For instance, consider a wrap angle diagram along an upward curve. As an example, blade 590 can be defined using one or more equations, parameters, etc., of the airfoil or impeller.

[0061] The turbine impeller may include the outer diameter of the blade at the tip point 593 of the leading edge 591 (e.g., the edge of the inlet section); another outer diameter of the blade at the tip point 595 of the trailing edge 599 (e.g., the edge of the outlet section); and the blade diameter at the hub point 594 of the trailing edge 599 (e.g., the edge of the outlet section).

[0062] As mentioned, a circle can be inscribed in the blade feature to define the diameter. As an example, the diameter D... le (Diameter leading edge) and diameter D te (The trailing edge of the diameter) may not correspond to a circle, but rather to a specific cross-section, in which a circle will have a diameter greater than D.le A slightly larger diameter, and the other circle will have a diameter greater than D. te Slightly larger diameter.

[0063] Figure 5 Arrows indicating the predetermined flow direction of exhaust gas from leading edge 591 to trailing edge 599 are also shown, wherein two adjacent blades define the flow path of exhaust gas (e.g., exhaust flow path). As mentioned, one side of the blade can be defined as the pressure side, while the opposite side of the blade can be defined as the suction side. Figure 5 The representation is a projected view, making the concave and convex shapes of the blade 590 with respect to the pressure and suction sides invisible.

[0064] As an example, a turbine impeller can be a radial-flow turbine impeller (e.g., radial inlet flow) or a mixed-flow turbine impeller (e.g., mixed inlet flow), wherein an angle can define at least a portion of the leading edge such that the inlet exhaust has radial and axial components. For mixed-flow turbine impeller blades, the leading edge forms an angle other than 90 degrees relative to the r-axis and an angle other than 0 degrees relative to the z-axis (e.g., approximately 1 degree to approximately 89 degrees). As an example, turbine impeller blades can be radially stacked or not radially stacked (e.g., non-radial stacked).

[0065] exist Figure 5 In the example, blade 590 is shown with an axial height Δz, which corresponds to the axial height of hub profile 596, and the blade is shown with an axial dimension Δz of the shroud edge between the tip point 593 of leading edge 591 and the tip point 595 of trailing edge 599. SE In the axial dimension Δz SE The radial dimension Δr can be defined along the axial span. SE-HP (z), which includes the minimum radial dimension within the axial span that is not at the z-coordinate of the tip point 593 or the z-coordinate of the tip point 595; instead, the minimum radial dimension is between the tip point 593 and the tip point 595.

[0066] exist Figure 5 In the example, the dashed line is illustrated as an extension between two points, which are depicted as open circles. The dashed line indicates that, from the perspective of blade 590, the hub profile 596 of blade 590 is concave. Specifically, the dashed line intersects the hub profile multiple times (e.g., at least twice). Accordingly, the axial dimension Δz of blade 590 at the shroud edge... SE The portion within the axial span is not convex because the hub profile 596 provides concavity.

[0067] The hub of a turbine impeller, which includes a set of blades (such as a set of blades 590), also has a concave shape. For example, consider... Figure 5The diagram shows a line drawn between two points in the hub, where the first point is at the edge of the guard with an axial dimension Δz. SE Within the range, and the second point is axially below the first point, such that the line crosses the hub profile 596 multiple times.

[0068] exist Figure 5 In the example, the corresponding turbine impeller hub can be considered to have a protrusion, wherein the radial dimension of the hub decreases, and then increases within the range of the increased axial dimension. Figure 5 In the example, the radial dimension decreases from a global maximum to a local minimum at backplate point 592, increases to a local maximum, and then decreases back to a global minimum. Figure 5 In the example, the hub profile 596 can be similarly defined (e.g., from global maximum to local minimum on the axial height Δz of blade 590, to local maximum to global minimum).

[0069] As an example, a turbocharger turbine impeller may include a hub with a radial protrusion between a back plate and a nose portion of the hub. For instance, the radial protrusion may extend across the axial midpoint of the blade, defined by a distance from the axial lowest point on the leading edge to the axial highest point on the trailing edge. Figure 5 In the example, the axial midpoint z is shown. mid The radial protrusion spans the axial midpoint z. mid As shown in the figure, the radial protrusion is offset by an axial distance from the axial lowest point 591 on the leading edge 590 of the blade 590, at the back disk point 592. As an example, the turbine impeller may include a leading edge that extends freely away from the back disk, such that the axial lowest point on the leading edge is lower than the back disk point. As an example, the radial protrusion may begin at the axial midpoint or otherwise cross the axial midpoint.

[0070] As an example, the radial protrusion can be defined by an axial dimension such as the axial span, wherein the axial span can be offset away from the axial lowest point of the leading edge of the blade and toward the axial highest point of the trailing edge of the blade. Figure 5 As shown in the example, the radial protrusion is offset toward the trailing edge 599 of the blade 590. As an example, the blade may include a radial defect region offset toward the axial lowest point on the leading edge of the blade.

[0071] As an example, a turbine rotor may include a hub with an arched hub profile, which can be customized for desired performance, as well as longer lifespan and durability, for example, with minimal possible mass and inertia. (See also: Regarding...) Figure 5As explained in hub profile 596, a radially inlet or mixed-inlet (e.g., radial and axial) turbine rotor may include a hub arched surface extending from a point at the leading edge to a point at the trailing edge. In such an example, the performance and durability of the turbine rotor may be increased, or the rotor's mass and inertia may be reduced, for example, without compromising performance. As an example, a method may be designed to achieve a balance between increased performance and / or durability and mass and inertia. For example, consider a method designed to provide the desired performance with minimal mass and inertia.

[0072] As an example, Figure 5 The hub profile 596 can be defined using one or more mathematical terms. As an example, at least a portion of the hub profile can be defined using parametric curves. In terms of differentiability, parametric curves can be defined partly by continuity. For example, C 0 Continuity means that the curves connect at the joint, C 1 Continuity means that the curves are connected as segments that share a common first derivative at the joint, and C n Continuity means that segments share the same nth derivative at the joint. As an example, the hub profile can be composed of segments with a derivative greater than C. 0 Continuity can be represented by a parametric curve. As an example, the hub profile can be represented by a parametric polynomial curve. As an example, the hub profile can be defined using one or more splines, and / or one or more blending functions. Some examples of splines include Hermite, Bezier, Catmull-Rom, and B-splines. As an example, the hub profile can be represented using control points, which can be joints. For example, hub profile 596 can be represented in the r, z plane using approximately 20 control points (e.g., consider 21 control points, etc.), which can be evenly spaced along hub profile 596 to define multiple segments, wherein the segments at the control points (e.g., joints) can have a value greater than C. 0 The continuity. In such an example, one or more splines can be used to define the hub profile 596.

[0073] Figure 6A , Figure 6B and Figure 6C Perspective, top, and bottom views of an example turbine impeller 660 (e.g., a turbine rotor) are shown, respectively. As shown, the turbine impeller 660 includes a shaft joint portion 665, a hub 670 with a nose 575, a back disk 680, and a plurality of blades 690. In such an example, the hub 670 of the turbine impeller 660 may be profiled to include, for example... Figure 5 The hub profile 596 in the figure shows the profile in which each of the plurality of blades 690 can be shaped as Figure 5 The leaves have 590.

[0074] As shown in the figure, the turbine impeller 660 can be driven by multiple blades 690 from the maximum diameter D. max Limited, wherein the back plate 680 can have a smaller diameter D bd .

[0075] Figure 7 An example of blade 790 is shown as a section comprising multiple blades of a turbine impeller. As shown, blade 790 includes a leading edge 791, a hub profile 796, a shroud profile 798, a trailing edge 799, and various points 792, 793, 794, and 795 that can be defined in a cylindrical coordinate system. Figure 7 In the exemplary blade 790, three radial lines, labeled r1, r2, and r3, are shown, each having corresponding axial coordinates z1, z2, and z3, where each of these three radial lines can be referred to as a radial fiber. Figure 7 In the middle, at z1, z2 and z3, three different r, The diagram illustrates the cross-sectional area and shape of the hub and blade 790 in a planar configuration. As an example, the blade may be partially defined by a thickness, which can be shown as a thickness Th at a specific axial dimension and a specific radial dimension. B (z,r). Blade thickness can be the distance between the pressure surface (e.g., pressure side) and suction surface (e.g., suction side) of the blade. Figure 7 In the example, blade 790 can have different thicknesses in different regions. As an example, the blade can be thinner at the shroud edge (e.g., along the shroud profile) and thicker at the hub edge (e.g., along the hub profile). Figure 7 As shown, the radius of the hub can vary, with the hub having a smaller radius near the nose and a larger radius near the base (e.g., where the blade 790 is connected to the back plate).

[0076] exist Figure 7 In the example, hub profile 796 is different. Figure 5 The hub profile 596 of the blade 590. In particular, the hub profile 596 can be described as a convexity relative to the blade 790, without the concavity shown by the hub profile 596 relative to the blade 590.

[0077] For comparative purposes, Figure 8 With similar Figure 7 A perspective view of blade 790 shows blade 590. As explained, the hub profile 596 of blade 590 differs from the hub profile 796 of blade 790. Various parameters described regarding blade 790 can be used to describe blade 590. In particular, refer to... Figure 5The radial dimension from hub profile 596 to guard edge 598 can be used in conjunction with radial and / or axial coordinates, dimensions, etc. (see, for example, r1, z1, r2, z2, r3, z3, etc.). Figure 8 As shown, with Figure 7 Compared to the blade root cross-section at z2 of blade 790, the intermediate cross-section of blade 590 at z2 tends to have a thicker blade root. As explained, two adjacent blades can define a channel or passage with suction and pressure sides. The shape of the channel or passage formed by the two blades 790 differs from that formed by the two blades 590. For example, consider flow along the hub surface of the channel or passage, where blade 590 can provide more axially guided flow due to the increased hub profile radius, followed by an increase in runoff due to the decreased hub profile radius 596.

[0078] Figure 9 and Figure 10 Side views of blade 590 are shown from both the pressure and suction sides. Figure 9 and Figure 10 In the view, fillets 571 and 573 are shown in the transition from hub 570 to blade 590. These fillets can provide structural support for blade 590. Fillets 571 and 573 can provide a smoother transition rather than a sharp corner transition, which may be beneficial for one or more purposes (e.g., stress, fluid dynamics, etc.). Figure 8 It also shows an approximate rounded corner transition.

[0079] Figure 11 A radial end view of blade 590 is shown, with the pressure side on the left and the suction side on the right. At least some portions of fillets 571 and 573 are also shown.

[0080] As explained, the turbine flow path between blades (airfoil components) is often an arc-shaped design without inflection points, and its impact on performance is not considered. (See again...) Figure 5 The dashed line represents a curved hub profile. In contrast, hub profile 596 includes at least one inflection point and may include multiple inflection points. For example, consider a hub profile with two inflection points. As described, dashed lines can be associated with convex shapes, while hub profile 596 can be associated with concave shapes (e.g., shapes with concavity). Dashed lines can define a smooth curved hub surface along the flow path direction, while hub profile 596 can define an arched hub surface along the flow path direction.

[0081] Figure 12 An exemplary diagram illustrating the relationship between turbine efficiency and turbine impeller speed (rpm) is provided. As shown, a turbine impeller 660 with a blade shape such as blade 590 exhibits improved turbine efficiency compared to another turbine impeller with different blades.

[0082] As explained, a turbocharger turbine impeller may include: a hub comprising a rotation axis, a back disk, and a nose, wherein the rotation axis defines an axial coordinate (z) in a cylindrical coordinate system, the cylindrical coordinate system including a radial coordinate (r) and an azimuth coordinate (r) along a predetermined direction of rotation about the rotation axis. ); and blades extending outward from the hub, wherein each of the blades includes a hub profile, a shield edge, a leading edge, a trailing edge, a pressure side, and a suction side, wherein the hub profile includes a global maximum radius and a global minimum radius, and wherein, between the global maximum radius and the global minimum radius, in the axial direction from the back plate to the nose, the hub profile includes a local minimum radius at a first axial coordinate position and a local maximum radius at a second axial coordinate position.

[0083] like Figure 8 As shown in the example, blade 590 may include a blade thickness measured between the suction and pressure sides. This thickness may represent a construction material having a corresponding material density that can define a mass. The distribution of mass or mass profile may affect the stress within the blade and / or turbine impeller. The total mass and / or mass distribution may also affect the operation of the bearing assembly. For example, a larger mass may require a larger bearing assembly to provide stability and life at operating turbine impeller speeds; however, this typically involves increased bearing assembly losses, which may reduce efficiency. A turbine impeller with blades such as blade 590 can achieve a reduction in both turbine impeller mass and bearing assembly size, both of which can result in performance gains and increased life. A turbine impeller with blades such as blade 590 can provide improved aerodynamic performance and increased life. As an example, blade 590 may increase turbine impeller performance and durability or reduce turbine impeller mass and inertia, optionally without compromising performance, or blade 590 may increase performance and durability while reducing mass and inertia. Blades such as the Blade 590 can provide customized performance with minimal mass and inertia.

[0084] As an example, a turbocharger turbine impeller may include: a hub comprising a rotation axis, a back disk, and a nose, wherein the rotation axis defines an axial coordinate (z) in a cylindrical coordinate system, the cylindrical coordinate system including a radial coordinate (r) and an azimuth coordinate (r) along a predetermined direction of rotation about the rotation axis. The hub includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side; and blades extending outward from the hub, each of which includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side. The hub profile includes a global maximum radius and a global minimum radius, and between the global maximum radius and the global minimum radius, in the axial direction from the backplate to the nose, the hub profile includes a local minimum radius at a first axial coordinate position and a local maximum radius at a second axial coordinate position. In such an example, the hub profile may include an inflection point between the local minimum radius and the local maximum radius.

[0085] As an example, a turbocharger turbine impeller may include a hub with a radial protrusion between a back plate of the hub and a nose portion of the hub. For example, the radial protrusion may extend across the axial midpoint of the blade, defined by the axial lowest point on the leading edge of the blade to the axial highest point on the trailing edge of the blade.

[0086] As an example, a turbocharger turbine impeller may include blades and a fillet that transitions from the surface of the hub to a pressure surface of one of the blades.

[0087] As an example, a turbocharger turbine impeller may include blades and a rounded corner from the surface of the hub to the suction surface of a corresponding blade.

[0088] As an example, a turbocharger turbine impeller may include blades and a first fillet that transitions from the surface of the hub to the pressure surface of a first blade and a second fillet that transitions from the surface of the hub to the suction surface of a second blade, wherein, at an axial coordinate position greater than the axial coordinate position of the free tip of the leading edge of the first blade, a point on the edge of the first fillet is spaced less than 1 mm from a point on the edge of the second fillet, or for example, the point on the edge of the first fillet may be spaced less than 0.1 mm from a point on the edge of the second fillet, or for example, the point on the edge of the first fillet may intersect with the point on the edge of the second fillet.

[0089] As an example, a turbocharger turbine impeller may include blades and a first fillet that transitions from a surface of the hub to a pressure surface of a first blade and a second fillet that transitions from a surface of the hub to a suction surface of a second blade. The point on the edge of the first fillet and the point on the edge of the second fillet may be spaced less than 1 mm apart at an axial coordinate position greater than the axial coordinate position of the free tip of the leading edge of the first blade. In such an example, the point on the edge of the first fillet and the point on the edge of the second fillet may be spaced more than 1 mm apart at an axial coordinate position less than the axial coordinate position of the free tip of the leading edge of the first blade.

[0090] As an example, a turbocharger turbine impeller may include blades, each of which has a leading edge including a mixing leading edge. For example, the mixing leading edge may be defined by an angle such as a cone angle. The mixing leading edge can guide flow radially and axially; while the runoff leading edge is generally designed to guide flow radially. As an example, a turbocharger turbine impeller may include blades, each of which has a leading edge including a runoff leading edge.

[0091] As an example, a turbocharger turbine impeller may include blades extending outward from a hub, each of which includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, wherein the hub profile includes a global maximum radius and a global minimum radius, and wherein, between the global maximum radius and the global minimum radius, in the axial direction from the back plate to the nose, the hub profile includes a local minimum radius at a first axial coordinate position and a local maximum radius at a second axial coordinate position, wherein, for example, the first axial coordinate position may be within 20% of the axial coordinate position of the free tip of the leading edge of one of the blades.

[0092] As an example, a turbocharger turbine impeller may include blades extending outward from a hub, each of which includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, wherein the hub profile includes a global maximum radius and a global minimum radius, and wherein, between the global maximum radius and the global minimum radius, in the axial direction from the back plate to the nose, the hub profile includes a local minimum radius at a first axial coordinate position and a local maximum radius at a second axial coordinate position, wherein, for example, the first axial coordinate position may be smaller than the axial coordinate position of the free tip of the leading edge of one of the blades.

[0093] As an example, a turbocharger turbine impeller may include blades extending outward from a hub, each of which includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, wherein the hub profile includes a global maximum radius and a global minimum radius, and wherein, between the global maximum radius and the global minimum radius, in the axial direction from the back plate to the nose, the hub profile includes a local minimum radius at a first axial coordinate position and a local maximum radius at a second axial coordinate position, wherein, for example, the second axial coordinate position may be greater than the axial coordinate position of the free tip of the leading edge of one of the blades.

[0094] As an example, a turbocharger turbine impeller may include blades, wherein the root thickness of one of the blades increases relative to the increased axial coordinate position over at least a portion of the axial span between the axial coordinate position of the free tip of the leading edge of one of the blades and the axial coordinate position of the end of the hub profile at the trailing edge of one of the blades.

[0095] As an example, a turbocharger turbine impeller may include multiple blades with a number of blades greater than 3 and less than 30.

[0096] As an example, a turbocharger turbine impeller may include a hub profile that includes an S-shape.

[0097] As an example, a turbocharger turbine impeller may include blades extending outward from a hub, each of which includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, wherein the hub profile includes a global maximum radius and a global minimum radius, and wherein, between the global maximum radius and the global minimum radius, in the axial direction from the backplate to the nose, the hub profile includes a local minimum radius at a first axial coordinate position and a local maximum radius at a second axial coordinate position, wherein, for example, the radial coordinate position of the hub profile is not monotonic relative to the increasing axial coordinate position in the direction from the backplate to the nose of the turbocharger impeller.

[0098] As an example, a turbocharger turbine impeller may include a hub profile, wherein the first derivative of the hub profile changes sign between a global maximum radius and a global minimum radius. As an example, the hub profile may be represented by a parametric curve including at least one joint, wherein the continuity at the joint is greater than C. 0 Continuity. Regarding differentiability, parametric curves can be partially defined by continuity. For example, C... 0 Continuity means that the curves connect at the joint, C 1 Continuity means that the curves are connected as segments that share a common first derivative at the joint, and Cn Continuity means that segments share the same nth derivative at the junction.

[0099] Although some examples of methods, devices, systems, arrangements, etc. have been shown in the accompanying drawings and described in the foregoing detailed embodiments, it will be understood that the disclosed exemplary embodiments are not limiting, but are capable of many rearrangements, modifications, and substitutions.

Claims

1. A turbocharger turbine impeller, comprising: A hub, comprising a rotation axis, a back plate, and a nose, wherein the rotation axis defines an axial coordinate (z) in a cylindrical coordinate system, the cylindrical coordinate system including a radial coordinate (r) and an azimuth coordinate (r) along a predetermined rotational direction about the rotation axis. );as well as Blades extending outward from the hub, each of which includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, wherein the hub profile includes a global maximum radius and a global minimum radius, and wherein, between the global maximum radius and the global minimum radius, in the axial direction from the back plate to the nose, the hub profile includes a local minimum radius at a first axial coordinate position and a local maximum radius at a second axial coordinate position. Wherein, the first axial coordinate position is smaller than the second axial coordinate position.

2. The turbocharger turbine impeller according to claim 1, wherein, The hub profile includes the inflection point between the local minimum radius and the local maximum radius.

3. The turbocharger turbine impeller according to claim 1, wherein, The hub includes a radial protrusion between the back plate and the nose.

4. The turbocharger turbine impeller of claim 1, comprising a fillet that transitions from the surface of the hub to the pressure surface of a corresponding blade.

5. The turbocharger turbine impeller of claim 1, comprising a rounded corner transitioning from the surface of the hub to the suction surface of a corresponding one of the blades.

6. The turbocharger turbine impeller of claim 1, comprising a first fillet transitioning from the surface of the hub to the pressure surface of a first blade among the blades and a second fillet transitioning from the surface of the hub to the suction surface of a second blade among the blades, wherein, At an axial coordinate position greater than the axial coordinate position of the free tip of the leading edge of the first blade in the blade, the point on the edge of the first fillet is less than 1 mm apart from the point on the edge of the second fillet.

7. The turbocharger turbine impeller according to claim 6, wherein, The point on the edge of the first rounded corner is less than 0.1 mm away from the point on the edge of the second rounded corner.

8. The turbocharger turbine impeller according to claim 6, wherein, The point on the edge of the first rounded corner intersects with the point on the edge of the second rounded corner.

9. The turbocharger turbine impeller according to claim 6, wherein, At the axial coordinate position of the free tip of the leading edge of the first blade, which is smaller than the axial coordinate position of the blade, the point on the edge of the first fillet is spaced more than 1 mm apart from the point on the edge of the second fillet.

10. The turbocharger turbine impeller according to claim 1, wherein, The leading edge includes a mixed-flow leading edge.

11. The turbocharger turbine impeller according to claim 1, wherein, The leading edge includes the runoff leading edge.

12. The turbocharger turbine impeller according to claim 1, wherein, The first axial coordinate position is within 20% of the axial coordinate position of the free tip of the leading edge of one of the blades.

13. The turbocharger turbine impeller according to claim 1, wherein, The first axial coordinate position is less than the axial coordinate position of the free tip of the leading edge of one of the blades.

14. The turbocharger turbine impeller according to claim 1, wherein, The second axial coordinate position is greater than the axial coordinate position of the free tip of the leading edge of one of the blades.

15. The turbocharger turbine impeller according to claim 1, wherein, The root thickness of one of the blades increases relative to the increased axial coordinate position over at least a portion of the axial span between the axial coordinate position of the free tip of the leading edge of one of the blades and the axial coordinate position of the end of the hub profile at the trailing edge of one of the blades.

16. The turbocharger turbine impeller of claim 1, comprising blades having a number greater than 3 and less than 30.

17. The turbocharger turbine impeller according to claim 1, wherein, The hub profile includes an S-shape.

18. The turbocharger turbine impeller according to claim 1, wherein, The radial coordinate position of the hub profile is not monotonic relative to the increased axial coordinate position in the direction from the back plate to the nose.

19. The turbocharger turbine impeller according to claim 1, wherein, The first derivative of the hub profile changes sign between the global maximum radius and the global minimum radius.

20. The turbocharger turbine impeller according to claim 1, wherein, The hub profile is represented by a parametric curve including at least one joint, wherein the continuity at the joint is greater than C. 0 Continuity.

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