Patent Description:
A turbocharger can include a rotating group that includes a turbine wheel and a compressor wheel that are connected to one another by a shaft. For example, a turbine wheel can be welded or otherwise connected to a shaft to form a shaft and wheel assembly (SWA) and a compressor wheel can be fit to the free end of the shaft. As an example, a shaft that is attached to one or more bladed wheels may be supported by one or more bearings disposed in a bearing housing, which may form a center housing rotating assembly (CHRA). During operation of a turbocharger, depending on factors such as size of various components, a SWA may be expected to rotate at speeds in excess of <NUM>,<NUM> rpm. Documents cited during prosecution include <CIT>; <CIT>; and <CIT>.

A more complete understanding of the various methods, devices, assemblies, systems, arrangements, etc., described herein, and equivalents thereof, may be had by reference to the following detailed description when taken in conjunction with examples shown in the accompanying drawings where:.

The invention relates to a turbocharger turbine wheel according to the appended claim <NUM>, and embodiment are defined in the appended claims.

Below, an example of a turbocharged engine system is described followed by various examples of components, assemblies, methods, etc..

Turbochargers are frequently utilized to increase output of an internal combustion engine. Referring to <FIG>, as an example, a system <NUM> can include an internal combustion engine <NUM> and a turbocharger <NUM>. As shown in <FIG>, the system <NUM> may be part of a vehicle <NUM> where the system <NUM> is disposed in an engine compartment and connected to an exhaust conduit <NUM> that directs exhaust to an exhaust outlet <NUM>, for example, located behind a passenger compartment <NUM>. In the example of <FIG>, a treatment unit <NUM> may be provided to treat exhaust (e.g., to reduce emissions via catalytic conversion of molecules, etc.).

As shown in <FIG>, the internal combustion engine <NUM> includes an engine block <NUM> housing one or more combustion chambers that operatively drive a shaft <NUM> (e.g., via pistons) as well as an intake port <NUM> that provides a flow path for air to the engine block <NUM> and an exhaust port <NUM> that provides a flow path for exhaust from the engine block <NUM>.

The turbocharger <NUM> can act to extract energy from the exhaust and to provide energy to intake air, which may be combined with fuel to form combustion gas. As shown in <FIG>, the turbocharger <NUM> includes an air inlet <NUM>, a shaft <NUM>, a compressor housing assembly <NUM> for a compressor wheel <NUM>, a turbine housing assembly <NUM> for a turbine wheel <NUM>, another housing assembly <NUM> and an exhaust outlet <NUM>. The housing assembly <NUM> may be referred to as a center housing assembly as it is disposed between the compressor housing assembly <NUM> and the turbine housing assembly <NUM>.

In the turbocharger <NUM> of <FIG>, the shaft <NUM> may be a shaft assembly that includes a variety of components (e.g., consider a shaft and wheel assembly (SWA) where the turbine wheel <NUM> is welded to the shaft <NUM>, etc.). As an example, the shaft <NUM> may be rotatably supported by a bearing system (e.g., journal bearing(s), rolling element bearing(s), etc.) disposed in the housing assembly <NUM> (e.g., in a bore defined by one or more bore walls) such that rotation of the turbine wheel <NUM> causes rotation of the compressor wheel <NUM> (e.g., as rotatably coupled by the shaft <NUM>). As an example a center housing rotating assembly (CHRA) can include the compressor wheel <NUM>, the turbine wheel <NUM>, the shaft <NUM>, the housing assembly <NUM> and various other components (e.g., a compressor side plate disposed at an axial location between the compressor wheel <NUM> and the housing assembly <NUM>).

In the example of <FIG>, a variable geometry assembly <NUM> is shown as being, in part, disposed between the housing assembly <NUM> and the housing assembly <NUM>. Such a variable geometry assembly may include vanes or other components to vary geometry of passages that lead to a turbine wheel space in the turbine housing assembly <NUM>. As an example, a variable geometry compressor assembly may be provided.

In the example of <FIG>, a wastegate valve (or simply wastegate) <NUM> is positioned proximate to an exhaust inlet of the turbine housing assembly <NUM>. The wastegate valve <NUM> can be controlled to allow at least some exhaust from the exhaust port <NUM> to bypass the turbine wheel <NUM>. Various wastegates, wastegate components, etc., may be applied to a conventional fixed nozzle turbine, a fixed-vaned nozzle turbine, a variable nozzle turbine, a twin scroll turbocharger, etc. As an example, a wastegate may be an internal wastegate (e.g., at least partially internal to a turbine housing). As an example, a wastegate may be an external wastegate (e.g., operatively coupled to a conduit in fluid communication with a turbine housing).

In the example of <FIG>, an exhaust gas recirculation (EGR) conduit <NUM> is also shown, which may be provided, optionally with one or more valves <NUM>, for example, to allow exhaust to flow to a position upstream the compressor wheel <NUM>.

<FIG> also shows an example arrangement <NUM> for flow of exhaust to an exhaust turbine housing assembly <NUM> and another example arrangement <NUM> for flow of exhaust to an exhaust turbine housing assembly <NUM>. In the arrangement <NUM>, a cylinder head <NUM> includes passages <NUM> within to direct exhaust from cylinders to the turbine housing assembly <NUM> while in the arrangement <NUM>, a manifold <NUM> provides for mounting of the turbine housing assembly <NUM>, for example, without any separate, intermediate length of exhaust piping. In the example arrangements <NUM> and <NUM>, the turbine housing assemblies <NUM> and <NUM> may be configured for use with a wastegate, variable geometry assembly, etc..

In <FIG>, an example of a controller <NUM> is shown as including one or more processors <NUM>, memory <NUM> and one or more interfaces <NUM>. Such a controller may include circuitry such as circuitry of an engine control unit (ECU). As described herein, various methods or techniques may optionally be implemented in conjunction with a controller, for example, through control logic. 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 the controller <NUM> via the one or more interfaces <NUM>. Control logic may rely on such information and, in turn, the controller <NUM> may output control signals to control engine operation. The controller <NUM> may be configured to control lubricant flow, temperature, a variable geometry assembly (e.g., variable geometry compressor or turbine), a wastegate (e.g., via an actuator), an electric motor, or one or more other components associated with an engine, a turbocharger (or turbochargers), etc. As an example, the turbocharger <NUM> may include one or more actuators and/or one or more sensors <NUM> that may be, for example, coupled to an interface or interfaces <NUM> of the controller <NUM>. As an example, the wastegate <NUM> may be controlled by a controller that includes an actuator responsive to an electrical signal, a pressure signal, etc. As an example, an actuator for a wastegate may be a mechanical actuator, for example, that may operate without a need for electrical power (e.g., consider a mechanical actuator configured to respond to a pressure signal supplied via a conduit).

<FIG> shows an example of a turbocharger <NUM> that includes a turbine assembly <NUM>, a compressor assembly <NUM> and a center housing <NUM>. The turbine assembly <NUM> includes a turbine housing <NUM> that is shaped to accommodate a turbine wheel <NUM> and the compressor assembly <NUM> includes a compressor housing <NUM> that is shaped to accommodate a compressor wheel <NUM>. As shown, a shaft <NUM> operatively couples the turbine wheel <NUM> and the compressor wheel <NUM> as supported by one or more bearings <NUM> and <NUM> in a through bore of the center housing <NUM>.

As shown in <FIG>, the turbine housing <NUM> can include an exhaust inlet <NUM> and an exhaust outlet <NUM> where a volute <NUM> is defined at least in part by the turbine housing <NUM>. The volute <NUM> can be referred to as a scroll that decreases in its cross-sectional diameter as it spirals inwardly toward a turbine wheel space that accommodates the turbine wheel <NUM>.

As shown in <FIG>, the compressor housing <NUM> can include an air inlet <NUM> and an air outlet <NUM> where a volute <NUM> is defined at least in part by the compressor housing <NUM>. The volute <NUM> can be referred to as a scroll that increases in its cross-sectional diameter as it spirals outwardly from a compressor wheel space that accommodates the compressor wheel <NUM>.

Disposed between the compressor housing <NUM> and the center housing <NUM> is a backplate <NUM>, which includes a bore <NUM> that can receive a thrust collar <NUM>, which can abut against a base end <NUM> of the compressor wheel <NUM>. As shown, the thrust collar <NUM> can include a lubricant slinger <NUM> that extends radially outward, which can help to reduce undesirable flow of lubricant (e.g., to the compressor wheel space, etc.).

The center housing <NUM> includes various lubricant features such as a lubricant inlet <NUM>, a lubricant bore <NUM>, lubricant jets <NUM>, and a lubricant drain <NUM>. As shown, lubricant can be provided at the lubricant inlet <NUM> to flow to the lubricant bore <NUM> and to the lubricant jets <NUM>, which include a compressor side jet for directing lubricant to the bearing <NUM> and a turbine side jet for directing lubricant to the bearing <NUM>. Lubricant can carry heat energy away from the bearings <NUM> and <NUM> as they rotatably support the shaft <NUM> as the turbine wheel <NUM> is driven by flow of exhaust through the turbine housing <NUM>.

As shown in the example of <FIG>, the compressor housing <NUM> can be clipped to the backplate <NUM> via a clip <NUM>, the backplate <NUM> can be bolted to the center housing <NUM> via bolt or bolts <NUM> and the center housing <NUM> can be bolted to the turbine housing <NUM> via a bolt or bolts <NUM>; noting that various other techniques may be utilized to couple the components to form a turbocharger.

In the example of <FIG>, one or more of the housings <NUM>, <NUM> and <NUM> may be cast. For example, the turbine housing <NUM> may be cast from iron, steel, nickel alloy, etc. As an example, consider a Ni-Resist cast iron alloy with a sufficient amount of nickel to produce an austenitic structure. For example, consider nickel being present from approximately <NUM> percent by weight to approximately <NUM> percent by weight. As an example, an increased amount of nickel can provide for a reduced coefficient of thermal expansion (e.g., consider a minimum at approximately <NUM> percent by weight). However, increased nickel content can increase cost of an Ni-Resist material; noting that density tends to be relatively constant over a large range of nickel content (e.g., approximately <NUM> to <NUM> grams per cubic centimeter). The density of Ni-Resist material tends to be approximately <NUM> percent higher than for gray cast iron and approximately <NUM> percent lower than cast bronze alloys. As to machinability, Ni-Resist materials tend to be better than cast steels; noting that increased chromium content tends to decrease machinability due to increasing amounts of hard carbides. When compared to stainless steel (e.g., density of approximately <NUM> grams per cubic centimeter), Ni-Resist materials can be less costly and of lesser mass (e.g., lesser density).

Ni-Resist materials tend to exhibit suitable high temperature properties, which may be at rated to over <NUM> degrees C (<NUM> degrees F). Ni-Resist materials can be suitable for turbocharges for diesel and gasoline internal combustion engines. As an example, a diesel engine can have exhaust that may be at about <NUM> degrees C and, as an example, a gasoline engine can have exhaust that may be at about <NUM> degrees C. Such exhaust can be received by a turbine assembly that includes a turbine housing made of a suitable material.

As shown, the turbine housing <NUM> may be a relatively large component when compared to the compressor housing <NUM> and the center housing <NUM> such that the mass of the turbine housing <NUM> contributes significantly to the mass of the turbocharger <NUM>.

In the example of <FIG>, various components of the turbocharger <NUM> may be defined with respect to a cylindrical coordinately system that includes a z-axis centered on a through bore of the center housing <NUM>, which can coincide with the rotational axis of a rotating assembly that includes the turbine wheel <NUM>, the compressor wheel <NUM> and the shaft <NUM>. As mentioned, a turbine wheel may be welded to a shaft to form a shaft and wheel assembly (SWA) and a compressor wheel may be threaded onto an end of a shaft (e.g., a "boreless" compressor wheel) or have a through bore that receives a free end of the shaft where a nut or other suitable component is used to secure the compressor wheel to the shaft. In the example of <FIG>, the turbine wheel <NUM> is welded to the shaft <NUM> and a nut <NUM> is used to secure the compressor wheel <NUM> to the shaft <NUM> and, hence, the turbine wheel <NUM>.

In the example of <FIG>, a clearance exists between blades <NUM> that extend from a hub <NUM> of the turbine wheel <NUM> and a shroud portion <NUM> of the turbine housing <NUM>. As shown, the shroud portion <NUM>, in the cross-sectional view is "J" shaped, which can define a body of rotation that has an annular ridge portion <NUM> and a cylindrical portion <NUM>. As shown, the annular ridge portion <NUM> can define a nozzle for exhaust that flows from the volute <NUM> to the turbine wheel space at an inducer portion of the turbine wheel <NUM>, which can be defined by leading edges where each of the blades <NUM> includes a leading edge (L. As shown, the turbine wheel <NUM> also includes an exducer portion where each of the blades <NUM> includes a trailing edge (T. During operation, exhaust flows from the volute <NUM> via the nozzle defined in part by the annular ridge portion <NUM> of the shroud portion <NUM> to the leading edges of the blades <NUM>, along channels defined by adjacent blades <NUM> of the turbine wheel <NUM> as confined between the hub <NUM> and the cylindrical portion <NUM> of the shroud portion <NUM> and then to the trailing edges of the blades <NUM> where the exhaust is confined by a larger diameter cylindrical wall <NUM>, a slightly conical wall <NUM> and a yet larger diameter cylindrical wall <NUM>. As shown in <FIG>, the cylindrical wall <NUM> can be defined by a portion of the turbine housing <NUM> that includes a fitting such as an annular ridge <NUM> that can be utilized to secure an exhaust conduit to the turbine housing <NUM>. Such an exhaust conduit may be in fluid communication with one or more other components such as an exhaust treatment unit, a muffler, another turbocharger, etc. As to the exhaust inlet <NUM> of the turbine housing <NUM>, it too may be shaped to couple to one or more exhaust conduits such as, for example, an exhaust header, an exhaust manifold, another turbine housing (e.g., for a multistage turbocharger arrangement), etc..

As shown in <FIG>, the turbine housing <NUM> severs various functions through its structural features and shapes thereof; however, such structural features can contribute to mass of the turbocharger.

As an example, a turbocharger may weigh from approximately <NUM> kilograms (e.g., <NUM> lbs) to approximately <NUM> kilograms (e.g., <NUM> lbs) or more.

As mentioned, a turbocharger can be defined with respect to a cylindrical coordinate system where a z-axis may be along a length. In the example of <FIG>, the length of the turbine housing <NUM> is over <NUM> percent of the total length. The overall length or size of a turbocharger can be a factor when installing in an engine compartment of a vehicle as it presents design constraints.

As an example, a turbocharger can include a turbine assembly with particular features that can improve performance and reduce mass and/or size of a turbocharger. For example, consider a turbine wheel that includes a conical region that is disposed between the leading edges and the trailing edges of the blades of the turbine wheel. For example, in <FIG>, the shroud portion <NUM> and blades <NUM> have a cylindrical shape as identified by the cylindrical portion <NUM>. In contrast, an example turbine assembly can include a shroud portion of a turbine housing and blades of a turbine wheel that include a conical shape that provides for a reduction in axial length of the turbine wheel or a lesser axial distance between a tip of a leading edge of a blade and a tip of a trailing edge of the blade. With a turbine wheel that includes a conical shape, a turbine housing may be made smaller and hence contribute to a reduction in length and/or mass of a turbocharger, which can translate into benefits for a vehicle that includes one or more of such turbochargers (e.g., lesser mass, lesser thermal mass to cool, faster cooling, more flexibility in arrangement in an engine compartment, a smaller engine compartment, etc.).

Additionally, or alternatively, performance can be improved by use of blades that include a conical portion where a turbine housing can include a shroud portion that includes a similar, matching conical portion. With increased performance, benefits may be realized, for example, as to balances between size, mass and performance.

As an example, a turbine wheel with a conical portion can provide performance benefits that can result in a reduction in overall size and mass of a turbine housing. For example, consider a reduction in volute size such that material demands can be reduced. As shown in <FIG>, the volute <NUM> is defined by the turbine housing <NUM>, particularly by an annular wall that has a cross-sectional "C" shape. As an example, a reduction in turbine wheel outer diameter can allow for a reduction in the maximum radius of a turbine housing (e.g., to form a volute that has a maximum radius).

The turbocharger <NUM> of <FIG> can be cooled via one or more media, such as lubricant (e.g., oil), water (e.g., radiator fluid, etc.), and air (e.g., via an environment with ambient air or vehicle engine compartment air).

As to lubricant cooling (e.g., oil, whether natural, synthetic, etc.), some tradeoffs exists. For example, if a carbonaceous lubricant reaches too high of a temperature for too long of a time (e.g., consider a time-temperature dependence), carbonization (e.g., also known as coke formation or "coking"), may occur. Coking can exasperate heat generation and heat retention by any of a variety of mechanisms and, over time, coke deposits can shorten the lifetime of a lubricated bearing system. As an example, coke deposits may cause a reduction in heat transfer and an increase heat generation, which may lead to failure of the bearing system. To overcome coking, a turbocharger may be configured to improve lubricant flow. For example, a pump may pressurize lubricant to increase flow rates to reduce residence time of lubricant in high temperature regions. However, an increase in lubricant pressure can exasperate various types of lubricant leakage issues. For example, an increase in lubricant pressure of a bearing system can result in leakage of lubricant to an exhaust turbine, to an air compressor or both. Escape via an exhaust turbine can lead to observable levels of smoke while escape via an air compressor can lead to lubricant entering an intercooler, combustion chambers (e.g., combustion cylinders), etc..

As to temperatures experienced during operation, they can depend on temperature of exhaust flowing to an exhaust turbine of a turbocharger, which can depend on whether an internal combustion engine is gasoline or diesel fueled (e.g., as mentioned, a diesel engine may have exhaust at about <NUM> degrees C and a gasoline engine may have exhaust at about <NUM> degrees C). Also, as to temperature, consider the example arrangements <NUM> and <NUM> of <FIG> where the turbine housing assemblies <NUM> and <NUM> are in close proximity to combustion cylinders, which may result in the turbine housing assemblies <NUM> and <NUM> experiencing higher exhaust temperatures and/or higher ambient temperatures.

<FIG> shows an example of a turbocharger <NUM> that includes a compressor assembly <NUM> with a compressor housing for a compressor wheel, a turbine assembly <NUM> with a turbine housing for a turbine wheel, a center housing <NUM> for a bearing, bearings or a bearing assembly to rotatably support a shaft of a shaft and wheel assembly (SWA), and an actuator <NUM> with a linkage <NUM> to a control arm assembly <NUM> for a wastegate of the turbine assembly <NUM>. The turbocharger <NUM> can include one or more of the components shown in <FIG>. In the view of <FIG>, the exhaust inlet of the turbine assembly <NUM> is not visible because it is on the opposite side. General directions of flow of air or exhaust are indicated by arrows. The actuator <NUM> is shown as being mounted to the compressor assembly <NUM>, which can help to reduce temperatures experienced by the actuator <NUM> (e.g., compared to having the actuator mounted on a turbine housing). The turbocharger <NUM> can be part of a vehicle such as, for example, the vehicle <NUM> of <FIG>. As an example, the turbine assembly <NUM> may optionally be arranged such as in one of the example arrangements <NUM> or <NUM> of <FIG>.

<FIG> shows a perspective view of a shaft and wheel assembly (SWA) <NUM>. As shown, the SWA <NUM> includes a shaft <NUM>, a seal portion <NUM> and a turbine wheel <NUM> where the turbine wheel <NUM> includes a nose <NUM>, a backdisk <NUM> and blades <NUM>. The turbine wheel <NUM> can be a single, unitary piece of material and referred to as a single component or a single piece. A portion of the turbine wheel <NUM> can be referred to as a hub <NUM>. For example, the backdisk <NUM> can be a part of the hub <NUM> from which the blades <NUM> extend. The hub <NUM> can include the backdisk <NUM> and the nose <NUM>, which includes a nose end <NUM>, and extend the length of the turbine wheel as indicated by an axial length ztw as measured along a rotational z-axis of the SWA <NUM>.

As an example, the seal portion <NUM> can be formed in part by the turbine wheel <NUM> and in part by the shaft <NUM>, can be formed by the shaft <NUM> or can be formed by the turbine wheel <NUM>. As an example, the seal portion <NUM> can be formed at least in part by the shaft <NUM>. The seal portion <NUM> can be defined by an outer radius. In <FIG>, a seal portion is shown as disposed at least in part in a turbine side bore opening of the center housing <NUM> where one or more seal elements (e.g., rings, etc.) are disposed in one or more annular grooves of the seal portion and/or of a turbine side bore wall that defines the turbine side bore opening. With reference to <FIG>, the seal portion can form a seal or seals between a lubricant region of the center housing <NUM> and an exhaust region in which the turbine wheel <NUM> is disposed.

As shown in <FIG>, the SWA <NUM> can include a shoulder or step down from the turbine wheel <NUM> toward the shaft <NUM>. For example, a shoulder can step down from an outer surface of the shaft joint portion <NUM> to an outer surface <NUM>, which may be at a radius equal to or approximately equal to that of the seal portion <NUM>. The shaft joint portion <NUM> can include a surface that is an annular axial face that can form a portion of a shoulder.

As an example, the shaft joint portion <NUM> can include a shaft joint surface that can be defined in part by a shaft joint radius. For example, consider a shaft joint surface that can be utilized to join a shaft to a turbine wheel (e.g., via welding, etc.). In such an example, the shaft joint surface of the turbine wheel can be a mating surface that mates with a turbine wheel joint surface of a shaft where the two surfaces can be brought into proximity or direct contact and joined (e.g., via welding). As an example, a shaft joint surface may be an annular surface that can be welded to a surface of a shaft to form a SWA (e.g., to form a weld or welds).

The SWA <NUM> can include dimensions such as, for example, axial dimensions for a compressor wheel portion zc, which may include one or more pilot surfaces, a set of threads, etc., and a bearing portion zj, which may include one or more journal surfaces (e.g., a compressor side journal surface and a turbine side journal surface, etc.).

As shown in <FIG>, the seal portion <NUM> can include one or more annular grooves that may be configured to receive one or more seal elements (e.g., one or more seal rings). As shown, the seal portion <NUM> can be defined in part by an axial dimension zsp. As an example, a seal element can be a split ring such as, for example, a piston ring. As mentioned, a SWA may be formed by welding a shaft to a turbine wheel such that the resulting SWA has a shaft and a turbine wheel arranged and fixed along a common rotational axis.

<FIG> shows an enlarged perspective view of a portion of the SWA <NUM>, specifically the turbine wheel <NUM>. As an example, a turbine wheel may be defined using diameters, which can be circles that inscribe features of the turbine wheel. For example, where a turbine wheel includes an odd number of blades, a diameter as a line may not be drawn from a leading edge of one blade to a leading edge of another blade. In such an example, diameter can be defined via a circle that inscribes the leading edges of the blades or, for example, mathematically, as twice a radius. A turbine wheel may be defined by an inducer diameter (e.g., associated with exhaust inflow) and an exducer diameter (e.g., associated with exhaust outflow). As an example, an inducer diameter can exceed an exducer diameter. As an example, a trim of a turbine wheel can be defined using its inducer diameter and its exducer diameter. Where diameter is mentioned, it may refer to a diameter of a circle that can be drawn with respect to features of a turbine wheel. As an example, a turbine wheel may be defined in a cylindrical coordinate system that includes axial, radial and azimuthal coordinates (e.g., r, z, and □).

As an example, a balancing process may alter one or more dimensions of a turbine wheel, for example, via removal of material. For example, consider removal of material from the nose <NUM> of the turbine wheel <NUM> of the SWA <NUM>. As shown, the nose <NUM> has an outer diameter that is less than an outer diameter of the backdisk <NUM>. Another option can be to remove material from the backdisk <NUM>. As an example, material may be removed from the shaft joint portion <NUM>. In such an example, material removal may have minimal impact on the backdisk <NUM> as to its ability to support the blades <NUM>.

As shown in the example of <FIG>, an exhaust turbocharger turbine wheel <NUM> can include the hub <NUM> that includes the nose <NUM>, the backdisk <NUM>, a shaft joint portion <NUM> (e.g., as part of the backdisk <NUM>) and a rotational axis (z-axis); the blades <NUM> that extend from the hub <NUM> to define exhaust flow channels where each of the blades <NUM> includes a leading edge (L. ), a trailing edge (T. ), a hub profile, a shroud profile defined by a shroud edge (S. ), a pressure side (P. ), and a suction side (S. ); where the backdisk <NUM> includes an outer perimeter radius measured from the rotational axis of the hub <NUM> and an intermediate radius at an outer perimeter of the shaft joint portion <NUM> measured from the rotational axis of the hub <NUM>.

As to the shaft joint portion <NUM>, it is shown as being substantially cylindrical. As an example, the backdisk <NUM> can be defined as a lower portion of the hub <NUM> that includes at least part of the shaft joint portion <NUM> and that extends outwardly to a maximum outer perimeter of the backdisk <NUM>.

As explained, the shaft joint portion <NUM> can join the seal portion <NUM>, which may be an integral part of the shaft <NUM>. As an example, the seal portion <NUM> can be welded to the shaft joint portion <NUM> to form a welded joint that is to permanently join the shaft <NUM> and the turbine wheel <NUM> to form the shaft and wheel assembly (SWA) <NUM>.

As an example, a shaft may be made of a material that is the same as that of a turbine wheel or that is different from that of a turbine wheel. Where materials differ, the materials can generally be amenable to welding such that a SWA can be formed. As an example, a compressor wheel may be manufactured from a material that has a lesser specific gravity than a material of a turbine wheel. In general, a compressor wheel experiences operational temperatures that are less than those of a turbine wheel. As an example, a turbine wheel can be made of a nickel alloy. For example, consider a NiCrFe-based alloy (e.g., HASTALLOY™ material, INCONEL™ material, etc.) or another alloy. In contrast, a compressor wheel may be made of a lighter material such as, for example, aluminum or an aluminum alloy. A turbine wheel material may have a specific gravity that is double or more than double that of aluminum (approximately <NUM> versus approximately <NUM> for INCONEL™ <NUM> material).

A rotating assembly can have a mass defined by a sum of individual masses of components that make up the rotating assembly (see, e.g., <FIG> where a rotating assembly includes the turbine wheel <NUM>, the compressor wheel <NUM> and the shaft <NUM>). As mentioned, flow of exhaust to an exhaust turbine disposed in a turbine housing can be a driver for rotation of a rotating assembly where mass and other factors can determine how much exhaust must flow before rotation commences.

<FIG> shows a representation of the invented blade <NUM> of a turbine wheel with respect to a r, z coordinate system where r is a radial coordinate and z is an axial coordinate where the z-axis is aligned with the rotational axis of the turbine wheel. As shown in <FIG>, the blade <NUM> includes various blade features such as a leading edge <NUM> (or inducer edge), a trailing edge <NUM> (or an exducer edge), a backdisk point <NUM> of the leading edge <NUM>, a tip point <NUM> of the leading edge <NUM>, a hub point <NUM> of the trailing edge <NUM>, a tip point <NUM> of the trailing edge <NUM>, a hub profile <NUM> that extends from the leading edge <NUM> to the trailing edge <NUM>, and a shroud edge <NUM> (e.g., a shroud profile) that extends from the leading edge <NUM> to the trailing edge <NUM>. As shown, the r-axis is orthogonal to the z-axis and at a z coordinate that corresponds to the backdisk point <NUM> of the leading edge <NUM>. Various points of the blade <NUM> can be described using the r, z coordinate system. In <FIG>, the blade <NUM> can be defined with respect to radial and axial coordinates. As an example, a polar angle plot may be utilized to provide for additional information that defines the blade <NUM>. For example, consider a plot of wrap angle along a camber line. As an example, the blade <NUM> may be defined using one or more equations, parameters, etc., of an airfoil or an impeller.

A turbine wheel can include a blade outer diameter at the tip point <NUM> of the leading edge <NUM> (e.g., inducer edge); another blade outer diameter at the tip point <NUM> of the trailing edge <NUM> (e.g., exducer edge); and a blade diameter at the hub point <NUM> at the trailing edge <NUM> (e.g., exducer edge).

As mentioned, a circle may inscribe blade features to define a diameter. As an example, a diameter Dle (diameter leading edge) and a diameter Dte (diameter trailing edge) may not correspond to circles but rather correspond to a particular cross-section, where a circle would have a slightly larger diameter than Dle and another circle would have a slightly larger diameter than Dte.

<FIG> also shows arrows that indicate intended direction of flow of exhaust, from the leading edge <NUM> to the trailing edge <NUM> where two adjacent blades define a flow channel for exhaust (e.g., an exhaust flow channel). As mentioned, one side of a blade can be defined as a pressure side while an opposing side of the blade can be defined as a suction side. The representation of <FIG> is a projected view such that the concave and convex shapes of the blade <NUM> as to pressure and suction sides are not seen.

As an example, a turbine wheel can be a radial flow turbine wheel (e.g., radial inlet flow) or can be a mixed-flow turbine wheel (e.g., mixed inlet flow) where an angle can define at least a portion of a leading edge such that incoming exhaust has both a radial component and an axial component. For a mixed-flow turbine wheel blade, a leading edge is at an angle other than <NUM> degrees with respect to the r-axis and is at an angle other than <NUM> degrees with respect to the z-axis (e.g., approximately <NUM> degree to approximately <NUM> degrees). As an example, a turbine wheel blade may be radially stacked or not radially stacked (e.g., non-radially stacked).

In <FIG>, the blade <NUM> is shown as having an axial height □z. which corresponds to the axial height of the hub profile <NUM> and the blade is shown as having a shroud edge axial dimension □zSE between the tip point <NUM> of the leading edge <NUM> and the tip point <NUM> of the trailing edge <NUM>. Over the axial span of the axial dimension □zSE, a radial dimension □rSE-HP(z) can be defined, which includes a minimum radial dimension within the axial span that is not at the z coordinate of the tip point <NUM> or at the z coordinate of the tip point <NUM>; rather, the minimum radial dimension is between the tip point <NUM> and the tip point <NUM>.

In <FIG>, a dotted line is illustrated as extending between two points, illustrated as open circles. The dotted line indicates that the hub profile <NUM> of the blade <NUM> is concave from the perspective of the blade <NUM>. Specifically, the dotted line intersects the hub profile multiple times (e.g., at least two times). As such, the portion of the blade <NUM> that is within the axial span of the shroud edge axial dimension □zSE is not convex as the hub profile <NUM> provides concavity.

A hub of a turbine wheel that includes a set of blades such as a set of the blades <NUM> has a concavity as well. For example, consider drawing a line between two points in the hub as shown in <FIG> where a first point is within the range of the shroud edge axial dimension □zSE and a second point is axially below the first point such that the line crosses the hub profile <NUM> multiple times.

In <FIG>, a corresponding turbine wheel hub is considered to have a bulge where the radial dimension of the hub decreases and then increases for a range of increasing axial dimension. In <FIG>, the radial dimension decreases from a global maximum at the backdisk point <NUM> to a local minimum, increases to a local maximum, and then decreases to a global minimum. In <FIG>, the hub profile <NUM> is defined similarly (e.g., from global maximum, to local minimum, to local maximum, to global minimum over the axial height □z of the blade <NUM>).

The turbocharger turbine wheel includes a hub with a radial bulge between a backdisk of the hub and a nose of the hub. The radial bulge spans an axial mid-point of a blade as defined from an axial lowermost point on a leading edge of the blade to an axial uppermost point on a trailing edge of the blade. <FIG>, an axial mid-point zmid is illustrated where a radial bulge spans the axial mid-point zmid. As shown, the radial bulge is offset an axial distance from the axial lowermost point, the backdisk point <NUM>, on the leading edge <NUM> of the blade <NUM>. The turbine wheel includes a leading edge that extends freely away from a backdisk such that an axial lowermost point on the leading edge is lower than a backdisk point. As an example, a radial bulge may commence at or otherwise span an axial mid-point.

The radial bulge is defined by an axial dimension such as an axial span where the axial span may be offset away from an axial lowermost point of a leading edge of a blade and toward an axial uppermost point of a trailing edge of the blade. As shown in <FIG>, the radial bulge is offset toward the trailing edge <NUM> of the blade <NUM>. The blade includes a radial deficit region that is offset toward an axial lowermost point on a leading edge of the blade.

As an example, a turbine rotor can include a hub with a cambered hub contour that can be tailored for desired performance and longer life and durability, for example, with minimum possible mass and inertia. As explained with respect to the hub profile <NUM> of <FIG>, a radial inlet or a mixed inlet (e.g., radial and axial) turbine rotor includes a hub cambered surface extending from a point at a leading edge to a point at a trailing edge. Performance and durability of the turbine rotor may increase or the mass and inertia of the rotor may decrease, for example, without a penalty on performance. As an example, an approach may aim to achieve a balance of increased performance and/or durability and mass and inertia. For example, consider an approach that aims to provide desired performance with minimal mass and inertia.

As an example, the hub profile <NUM> of <FIG> may be defined using one or more mathematical terms. As an example, a parametric curve may be utilized to define at least a portion of a hub profile. A parametric curve can be defined in part by continuity in terms of differentiability. For example, C<NUM> continuity means that a curve is connected at joints, C<NUM> continuity means that a curve is connected as segments that share a common first derivative at a joint, and Cn continuity means that segments share the same nth derivative at a joint. As an example, a hub profile may be represented by a parametric curve that has greater than C<NUM> continuity. As an example, a hub profile may be represented by a parametric polynomial curve. As an example, one or more splines may be utilized to define a hub profile and/or one or more blending functions may be utilized to define a hub profile. As to splines, some examples include Hermite, Bezier, Catmull-Rom and B-Spline. As an example, a hub profile may be represented using control points, which may be joints. For example, the hub profile <NUM> may be represented using approximately <NUM> control points (e.g., consider <NUM> control points, etc.) in a r,z-plane that may be evenly spaced along the hub profile <NUM> to define a number of segments where the segments can have greater than C<NUM> continuity at the control points (e.g., joints). In such an example, one or more splines may be utilized to define the hub profile <NUM>.

<FIG> show perspective, top and bottom views of an example of a turbine wheel <NUM> (e.g., a turbine rotor), respectively. As shown, the turbine wheel <NUM> includes a shaft joint portion <NUM>, a hub <NUM> with a nose <NUM>, a backdisk <NUM> and a plurality of blades <NUM>. In such an example, the hub <NUM> of the turbine wheel <NUM> can be contoured to include a profile as shown as the hub profile <NUM> in <FIG> where each of the plurality of blades <NUM> can be shaped as the blade <NUM> of <FIG>.

As shown, the turbine wheel <NUM> can be defined by a maximum diameter Dmax via the plurality of blades <NUM> where the backdisk <NUM> can be of a lesser diameter Dbd.

<FIG> shows an example of a blade <NUM> as a section of a turbine wheel that includes a plurality of blades. As shown, the blade <NUM> includes a leading edge <NUM>, a hub profile <NUM>, a shroud profile <NUM>, a trailing edge <NUM> and various points <NUM>, <NUM>, <NUM> and <NUM>, which may be defined in a cylindrical coordinate system. In the example blade <NUM> of <FIG>, three radial lines are shown, labeled r<NUM>, r<NUM> and r<NUM>, which have corresponding axial coordinates z<NUM>, z<NUM> and z<NUM>, where each of the three radial lines may be referred to as a radial fiber. In <FIG>, at three different r, □ planes at z<NUM>, z<NUM> and z<NUM>, cross-sectional areas and shapes of the hub and the blade <NUM> are illustrated. As an example, a blade can be defined in part by a thickness, which can be shown as the thickness ThB(z,r) at a particular axial dimension and a particular radial dimension. A blade thickness can be a distance that is between a pressure surface (e.g., a pressure side) and a suction surface (e.g., a suction side) of a blade. In the example of <FIG>, the blade <NUM> can have a thickness that various in different regions. As an example, a blade may be thinner at a shroud edge (e.g., along a shroud profile) and thicker at a hub edge (e.g., along a hub profile). As shown in <FIG>, the hub can vary in its radius where the hub can have a smaller radius near a nose and a larger radius near a base (e.g., where the blade <NUM> joins the backdisk).

In the example of <FIG>, the hub profile <NUM> differs from the hub profile <NUM> of the blade <NUM> of <FIG>. In particular, the hub profile <NUM> with respect to the blade <NUM> may be referred to as being convex, without concavity as illustrated by the hub profile <NUM> with respect to the blade <NUM>.

<FIG> shows the blade <NUM> in a perspective view akin to the view of the blade <NUM> of <FIG> for purposes of comparison. As explained, the hub profile <NUM> of the blade <NUM> differs from the hub profile <NUM> of the blade <NUM>. Various parameters described with respect to the blade <NUM> may be utilized to describe the blade <NUM>. In particular, referring to <FIG>, a radial dimension from the hub profile <NUM> to the shroud edge <NUM> may be utilized in combination with radial and/or axial coordinates, dimensions, etc. (see, e.g., r<NUM>,z<NUM>, r<NUM>,z<NUM>, r<NUM>,z<NUM>, etc.). As shown in <FIG>, the middle cross-section at z<NUM> tends to have a thicker blade root for the blade <NUM> compared to the blade root cross-section at z<NUM> for the blade <NUM> of <FIG>. As explained, two adjacent blades can define a channel or passage with a suction side and a pressure side. The shape of a channel or passage formed by two of the blades <NUM> differs from a channel or passage formed by two of the blades <NUM>. For example, consider flow along a hub surface of the channel or passage where the blade <NUM> can provide for more axially directed flow due to the hub profile increasing in radius followed by an increase in radial flow due to the hub profile <NUM> decreasing in radius.

<FIG> and <FIG> show side views of the blade <NUM> from the pressure side and the suction side, respectively. In the views of <FIG> and <FIG>, fillets <NUM> and <NUM> are shown in a transition from the hub <NUM> to the blade <NUM>. Such fillets can provide structural support for the blade <NUM>. Rather than a sharp corner transition, the fillets <NUM> and <NUM> can provide a smoother transition, which can be beneficial for one or more purposes (e.g., stress, fluid dynamics, etc.). <FIG> also shows approximate fillet transitions.

<FIG> shows a radial end view of the blade <NUM>, where the pressure side is to the left and the suction side is to the right. At least portions of the fillets <NUM> and <NUM> are also shown.

As explained, a turbine flow path between blades (airfoils) tends to be of an arc design with no inflexion points, without concern for its impact on performance. Referring again to <FIG>, a dashed line represents an arc design hub profile. In contrast, the hub profile <NUM> includes at least one inflection point and can include multiple inflection points. For example, consider a hub profile with two inflection points. As described, the dashed line can be associated with a convex shape while the hub profile <NUM> can be associated with a concave shape (e.g., a shape with a concavity). The dashed line can define a smooth arced hub surface in a flow path direction while the hub profile <NUM> can define a cambered hub surface in a flow path direction.

<FIG> shows an example plot of turbine efficiency versus turbine wheel speed (rpm). As shown, the turbine wheel <NUM> with blades shaped such as the blade <NUM> demonstrated improved turbine efficiency compared to another turbine wheel with different blades.

As explained, a turbocharger turbine wheel can include a hub that includes a rotational axis, a backdisk and a nose, where the rotational axis defines an axial coordinate (z) in a cylindrical coordinate system that includes a radial coordinate (r) and an azimuthal coordinate (□) in a direction of intended rotation about the rotational axis; and blades that extend outwardly from the hub, where each of the blades includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, where the hub profile includes a global maximum radius and a global minimum radius, and where, between the global maximum radius and the global minimum radius, in an axial direction from the backdisk 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.

As shown in the example of <FIG>, the blade <NUM> can include blade thicknesses measured between the suction side and the pressure side. The thickness can represent material of construction with a corresponding material density that can define a mass. Distribution of mass, or mass distribution, can affect stresses within a blade and/or a turbine wheel. Overall mass and/or mass distribution can also affect bearing assembly operation. For example, a larger mass can demand a larger bearing assembly to provide stability and longevity at operational turbine wheel speeds; however, generally with increased bearing assembly losses that can decrease efficiency. A turbine wheel with blades such as the blade <NUM> can provide for a reduction in turbine wheel mass and bearing assembly size, both of which can provide for performance gains as well as increased longevity. A turbine wheel with blades such as the blade <NUM> can provide improved aerodynamic performance and increased longevity. As an example, the blade <NUM> can increase performance and durability of a turbine wheel or decrease mass and inertia of a turbine wheel, optionally without a penalty on performance, or the blade <NUM> may increase performance and durability and decrease mass and inertia. A blade such as the blade <NUM> may provide for tailoring performance with minimal mass and inertia.

As an example, a turbocharger turbine wheel can include a hub that includes a rotational axis, a backdisk and a nose, where the rotational axis defines an axial coordinate (z) in a cylindrical coordinate system that includes a radial coordinate (r) and an azimuthal coordinate (□) in a direction of intended rotation about the rotational axis; and blades that extend outwardly from the hub, where each of the blades includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, where the hub profile includes a global maximum radius and a global minimum radius, and where, between the global maximum radius and the global minimum radius, in an axial direction from the backdisk 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 can include an inflection point between the local minimum radius and the local maximum radius.

As an example, a turbocharger turbine wheel can include a hub with a radial bulge between a backdisk of the hub and a nose of the hub. For example, the radial bulge may be span an axial mid-point of a blade as defined from an axial lowermost point on a leading edge of the blade to an axial uppermost point on a trailing edge of the blade.

As an example, a turbocharger turbine wheel can include blades and a fillet that transitions from a surface of a hub to a pressure surface of a respective one of the blades.

As an example, a turbocharger turbine wheel can include blades and a fillet that transitions from a surface of a hub to a suction surface of a respective one of the blades.

As an example, a turbocharger turbine wheel can include blades and a first fillet that transitions from a surface of a hub to a pressure surface of a first one of the blades and a second fillet that transitions from a surface of the hub to a suction surface of a second one of the blades, where, at an axial coordinate position that is greater than an axial coordinate position of a free tip of a leading edge of the first one of the blades, a point on an edge of the first fillet and a point on an edge of the second fillet are spaced apart by less than <NUM> or, for example, the point on the edge of the first fillet and the point on the edge of the second fillet can be spaced apart by less than <NUM> or, for example, the point on the edge of the first fillet and the point on the edge of the second fillet can meet.

As an example, a turbocharger turbine wheel can include blades and a first fillet that transitions from a surface of a hub to a pressure surface of a first one of the blades and a second fillet that transitions from a surface of the hub to a suction surface of a second one of the blades, where, at an axial coordinate position that is greater than an axial coordinate position of a free tip of a leading edge of the first one of the blades, a point on an edge of the first fillet and a point on an edge of the second fillet can be spaced apart by less than <NUM>. In such an example, at an axial coordinate position that is less than an axial coordinate position of the free tip of the leading edge of the first one of the blades, a point on an edge of the first fillet and a point on an edge of the second fillet can be spaced apart by more than <NUM>.

As an example, a turbocharger turbine wheel can include blades where a leading edge of each of the blades includes a mixed-flow leading edge. For example, a mixed-flow leading edge may be defined by an angle such as a cone angle. A mixed-flow leading edge can provide for directing flow radially and axially; whereas, a radial flow leading edge generally aims to direct flow radially. As an example, a turbocharger turbine wheel can include blades where a leading edge of each of the blades includes a radial-flow leading edge.

As an example, a turbocharger turbine wheel can include blades that extend outwardly from a hub, where each of the blades includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, where the hub profile includes a global maximum radius and a global minimum radius, and where, between the global maximum radius and the global minimum radius, in an axial direction from the backdisk 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 where, for example, the first axial coordinate position can be within <NUM> percent of an axial coordinate position of a free tip of the leading edge of one of the blades.

As an example, a turbocharger turbine wheel can include blades that extend outwardly from a hub, where each of the blades includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, where the hub profile includes a global maximum radius and a global minimum radius, and where, between the global maximum radius and the global minimum radius, in an axial direction from the backdisk 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 where, for example, the first axial coordinate position can be less than an axial coordinate position of a free tip of the leading edge of one of the blades.

As an example, a turbocharger turbine wheel can include blades that extend outwardly from a hub, where each of the blades includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, where the hub profile includes a global maximum radius and a global minimum radius, and where, between the global maximum radius and the global minimum radius, in an axial direction from the backdisk 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 where, for example, the second axial coordinate position can be greater than an axial coordinate position of a free tip of the leading edge one of the blades.

As an example, a turbocharger turbine wheel can include blades where a root thickness of one of the blades increases with respect to an increasing axial coordinate position over at least a portion of an axial span between an axial coordinate position of a free tip of a leading edge of the one of the blades and an axial coordinate position of an end of a hub profile at a trailing edge of the one of the blades.

As an example, a turbocharger turbine wheel can include a blade number of a number of blades that is greater than three and less than thirty.

As an example, a turbocharger turbine wheel can include a hub profile that includes an S-shape.

As an example, a turbocharger turbine wheel can include blades that extend outwardly from a hub, where each of the blades includes a hub profile, a shroud edge, a leading edge, a trailing edge, a pressure side, and a suction side, where the hub profile includes a global maximum radius and a global minimum radius, and where, between the global maximum radius and the global minimum radius, in an axial direction from the backdisk 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 where, for example, the radial coordinate position of the hub profile is not monotonic with respect to increasing axial coordinate position in a direction from a backplate to a nose of the turbocharger wheel.

As an example, a turbocharger turbine wheel can include a hub profile where a first derivative of the hub profile changes signs between a global maximum radius and a global minimum radius. As an example, a hub profile may be represented by a parametric curve that includes at least one joint, where continuity at the joint is greater than C<NUM> continuity. A parametric curve can be defined in part by continuity in terms of differentiability. For example, C<NUM> continuity means that a curve is connected at joints, C<NUM> continuity means that a curve is connected as segments that share a common first derivative at a joint, and Cn continuity means that segments share the same nth derivative at a joint.

Claim 1:
A turbocharger turbine wheel comprising:
a hub (<NUM>, <NUM>, <NUM>, <NUM>) that comprises a rotational axis, a backdisk (<NUM>, <NUM>) and a nose (<NUM>, <NUM>), wherein the rotational axis defines an axial coordinate (z) in a cylindrical coordinate system that comprises a radial coordinate (r) and an azimuthal coordinate (□) in a direction of intended rotation about the rotational axis; and
blades (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) that extend outwardly from the hub, wherein each of the blades comprises a hub profile (<NUM>, <NUM>), a shroud edge, a leading edge (<NUM>, <NUM>), a trailing edge (<NUM>, <NUM>), a pressure side, and a suction side, wherein the hub profile comprises 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 backdisk to the nose, the hub profile comprises a local minimum radius at a first axial coordinate position and a local maximum radius at a second axial coordinate position,
characterized in that,
a radial dimension of the hub is smaller at the local minimum radius as compared to a radial dimension of the hub at the local maximum radius, and the first axial coordinate position is less than an axial co-ordinate position of a free tip of the leading edge of one of the blades.