Turbocharger bearing housing

Abstract

A turbocharger bearing housing is disclosed. The turbocharger bearing housing includes a body that extends radially outward, forming a turbine end. The turbine end is formed to have a geometry complementary to the turbine wheel. A passage extending through the bearing housing is formed to allow fluid communication with an exterior of the bearing housing.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 63 / 468973 (filing date May 25, 2023), U.S. Provisional Application No. 63 / 522209 (filing date June 21, 2023), and U.S. Provisional Application No. 63 / 649094 (filing date May 17, 2024). TECHNICAL FIELD

[0003] The present invention relates generally to turbochargers, and in particular to bearing components and systems associated with turbochargers. BACKGROUND

[0004] A turbocharger is a device used in internal combustion engines and generators to increase their power output by compressing the incoming air, which acts as a forced induction system that utilizes exhaust gases to drive a turbine, which in turn drives a compressor. The turbocharger utilizes exhaust gas energy to force more air into the engine, thereby enhancing its performance. The compressor then supercharges the intake air, enabling more air to enter the engine's cylinders during each intake stroke. By compressing the incoming air, the turbocharger allows for a higher fuel-air ratio, thereby increasing power output and improving fuel efficiency. Turbochargers are commonly used in automotive and industrial applications to boost engine performance.

[0005] A turbine wheel is used in a turbocharger to increase the power and efficiency of internal combustion engines and generators. The turbine wheel is mounted on a shaft and rotates at high speed in response to exhaust gas flow. The primary function of the turbine wheel is to convert the energy of the exhaust gas into rotational energy, which is then used to drive the compressor wheel of the turbocharger. As exhaust gas passes through the turbine housing, it hits the turbine wheel's blades, causing them to spin rapidly. The rotation of the turbine wheel drives the compressor wheel at the other end of the shaft, which compresses fresh air and forces it into the engine's intake manifold or the generator's air intake system or air induction system. This compressed air allows for more fuel to be burned, thereby increasing power output.

[0006] The turbine wheel can rotate at a rotational speed of approximately hundreds of thousands of revolutions per minute. The turbine wheel is formed by a circular back wall, with turbine blades attached in a uniform circular pattern on one flat surface of the back wall. To provide lower inertia and lower stress along the back wall of the turbine wheel, the back wall can be scalloped between the turbine blades. However, conventional scallops can result in efficiency losses for the turbocharger.

[0007] The application of turbochargers is challenged by high temperatures and stresses, causing turbine wheels to be subjected to high thermal loads. Conventional turbocharger designs include thermal shields to minimize heat transfer from the turbine wheel to other components, such as the bearing housing or compressor side. These shields act as a thermal barrier between the turbine wheel and other turbocharger components, reducing heat transfer to sensitive areas, such as bearings, oil, and coolant systems. By providing a protective layer, thermal shields minimize heat transfer, reducing the risk of heat-related damage or performance degradation of surrounding components.

[0008] Others have attempted to provide solutions for thermal shields between turbine wheels and turbochargers, but have not disclosed designs that provide simplified components that avoid unwanted air circulation. For example, U.S. Patent 9797409 discloses a turbocharger having a bearing housing integrated with a thermal shield. However, this reference discloses the thermal shield and bearing housing as separate components that are assembled together, creating undesirable flow and cooling within the turbocharger. The thermal shield is challenging to assemble and can also be cumbersome during manufacturing. As the assembly of the thermal shield is complex and time-consuming, it is desirable to explore alternatives that can provide improved performance and are easier to install.

[0009] It can therefore be seen that there is a need for a turbocharger and bearing housing for engines and generators that sufficiently cools engine and generator components and provides improved airflow performance and is easier to install. SUMMARY

[0010] According to an aspect of the present application, a turbocharger bearing housing is disclosed. The turbocharger bearing housing includes a main body extending radially outward forming a turbine end. The turbine end is formed to have a geometry complementary to a turbine wheel. A channel is formed extending through the bearing housing to allow fluid communication with an exterior of the bearing housing.

[0011] According to another aspect of the present application, a turbocharger system is disclosed. The turbocharger system includes a bearing housing having a main body extending radially outward forming a turbine end having a geometry complementary to a turbine wheel, a shaft rotatably mounted within a shaft bore in the bearing housing, the turbine wheel disposed at an end of the shaft proximate the turbine end, and a channel extending through the bearing housing to allow fluid communication with an exterior of the bearing housing.

[0012] According to another aspect of the present application, a method of forming a bearing housing for a turbocharger is disclosed. The method includes casting a bearing housing having a main body with a turbine end extending radially outwardly toward a turbine wheel, the turbine end having a geometry complementary to the turbine wheel.

[0013] These and other aspects and features of the present application will be better understood when read with respect to the following detailed description of preferred embodiments, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a perspective view of a turbocharger according to one embodiment of the present application.

[0015] Figure 2 is a cross-sectional view of the turbocharger of Figure 1 taken along line 2-2.

[0016] Figure 3 is a cross-sectional view of the turbocharger of Figure 2 in the area around the turbine wheel according to one embodiment of the present application.

[0017] Figure 4 is a cross-sectional view of the turbocharger of Figure 2 in the area around the turbine wheel according to another embodiment of the present application.

[0018] Figure 5 is a cross-sectional view of the turbocharger of Figure 1 taken along line 2-2 according to another embodiment of the present application.

[0019] Figure 6 is an enlarged view of the heat shield of Figure 5 according to another embodiment of the present application.

[0020] Figure 7 is a perspective view of a turbine wheel according to one embodiment of the present application.

[0021] Figure 8 is an elevational view of a turbine wheel according to one embodiment of the present application.

[0022] Figure 9 is a flow chart of a method of forming a bearing housing for a turbocharger according to one embodiment of the present application.

[0023] Figure 10 is a perspective cross-sectional view of a turbocharger according to an embodiment of the present application.

[0024] Figure 11 is an elevational view of a turbine wheel according to an embodiment of the present application.

[0025] Figure 12 is a cross-sectional view taken along line 12-12 of the turbine wheel constructed in accordance with the present application. Figure 11

[0026] Figure 13 Figure 11 is an enlarged view of

[0027] Figure 14 Figure 12 is an enlarged cross-sectional view of

[0028] Figure 15 Figure 12 is an enlarged cross-sectional view of an alternative embodiment of the turbine wheel constructed in accordance with the present application.

[0029] Figure 16 Figure 12 is an enlarged cross-sectional view of an alternative embodiment of the turbine wheel constructed in accordance with the present application.

[0030] Figure 17 Figure 12 is an enlarged cross-sectional view of an alternative embodiment of the turbine wheel constructed in accordance with the present application.

[0031] Figure 18 is a perspective view of the turbine wheel constructed in accordance with the present application.

[0032] Figure 19 is a cross-sectional view taken along line 19-19 of the turbocharger constructed in accordance with the present application. Figure 10

[0033] Figure 20 is a cross-sectional view of the turbocharger constructed in accordance with the present application in the area surrounding the turbine wheel. Figure 19

[0034] Figure 21 is a flow chart representing an exemplary sequence of steps that can be implemented in accordance with the method of manufacturing a turbocharger in accordance with the present application.

[0035] Figure 22 Figure 1 is a cross-sectional view of the turbocharger constructed in accordance with the present application in the area surrounding the turbine wheel.

[0036] The accompanying drawings are included to provide a further understanding of an embodiment of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. Those of ordinary skill in the art will realize that other embodiments can be utilized and structural and methodological changes can be made without departing from the scope of the present application. DETAILED DESCRIPTION

[0037] ​​​​​​​​​With reference now to the drawing figures, and in particular to Figure 1 of the drawings, Figure 1

[0038] The turbocharger 100 includes a turbine wheel 102, a compressor 104, and a shaft 106 for rotatably coupling the turbine wheel 102 and the compressor 104. The shaft 106 extends through a bearing housing 108. The turbine wheel 102 can be located within a turbine housing, and the compressor 104 can be located in a compressor cover, as is generally known in the art. The compressor 104 can be a compressor wheel, as is generally known in the art. The shaft 106 can be disposed in a shaft bore 110 within the bearing housing 108.

[0039] The turbine wheel 102 can be rotationally driven by exhaust gases exiting the turbocharger 100. Rotation of the turbine wheel 102 is transmitted to the compressor 104 by the shaft 106. The compressor 104 can be used to increase the pressure of intake air before it is mixed with fuel for combustion in an engine or generator. Rotation of the turbine wheel 102 creates forced vortex flow, in which particle velocity and pressure vary proportionally with the radius of rotation.

[0040] With reference now to the drawing figures, and in particular to Figure 1 of the drawings, Figure 1 Figures 2-4 Figure 2 illustrates a cross-sectional view of the turbocharger 100 taken along line 2-2 of Figure 1, according to one embodiment of the present application. As shown in Figure 2, the shaft 106 can extend through the bearing housing 108 and be rotatably mounted within the bearing housing 108 in the shaft bore 110. The shaft 106 can have a plurality of bearings 112 mounted about the shaft 106. The plurality of bearings 112 can include journal bearings and / or ball bearings, as is generally known in the art. The shaft 106, turbine wheel 102, and compressor 104 can rotate at very high speeds, for example, in excess of 250,000 rpm. To support high speed rotation, oil can be utilized to lubricate the plurality of bearings 112 for supporting the shaft 106. Figure 1 Figure 2 As shown in Figure 2, the shaft 106 can extend through the bearing housing 108 and be rotatably mounted within the bearing housing 108 in the shaft bore 110. The shaft 106 can have a plurality of bearings 112 mounted about the shaft 106. The plurality of bearings 112 can include journal bearings and / or ball bearings, as is generally known in the art. The shaft 106, turbine wheel 102, and compressor 104 can rotate at very high speeds, for example, in excess of 250,000 rpm. To support high speed rotation, oil can be utilized to lubricate the plurality of bearings 112 for supporting the shaft 106.

[0041] As shown in Figure 2, the shaft 106 can extend through the bearing housing 108 and be rotatably mounted within the bearing housing 108 in the shaft bore 110. The shaft 106 can have a plurality of bearings 112 mounted about the shaft 106. The plurality of bearings 112 can include journal bearings and / or ball bearings, as is generally known in the art. The shaft 106, turbine wheel 102, and compressor 104 can rotate at very high speeds, for example, in excess of 250,000 rpm. To support high speed rotation, oil can be utilized to lubricate the plurality of bearings 112 for supporting the shaft 106. Figures 3-4 ​​​As shown, in the region surrounding the turbine wheel 102, the bearing housing 108 has a body 114 that extends radially to the turbine wheel 102, where a turbine end 116 is formed with a complementary geometry to the turbine wheel 102. The turbine end 116 can be formed in any suitable manner when forming the bearing housing 108, such as by casting, machining, shot peening, etc. The turbine end 116 extends in a substantially radially outward direction (taken along line 2-2) relative to the rotational axis of the shaft 106. The turbine end 116 faces the turbine wheel 102 and is formed to the geometry of the turbine wheel 102 that faces the compressor end 118 of the compressor 104.

[0042] The components within the bearing housing 108 (e.g., the bearing set 112) are protected from unwanted heat energy transfer from the exhaust gas in the turbine wheel 102 because the turbine end 116 blocks conductive and radiative heat flow from the exhaust gas through the bearing housing 108 back to the compressor end 118. By casting the turbine end 116 to the geometry of the turbine wheel 102, any adverse effects from the temperature rise within the turbocharger 100 are avoided, preventing heat from propagating and affecting components within the turbocharger 100 towards the compressor 104. The turbine end 116 also blocks heat flow from the exhaust gas to the seal ring, piston ring, and the plurality of bearings 112. The turbine end 116 of the bearing housing 108 is a heat shield formed integrally with the bearing housing 108.

[0043] The turbine end 116 can have various configurations as needed to complement the geometry of the turbine wheel 102. For example, the bearing housing 108 can have a substantially disc-shaped structure (without a flange). When the turbine end 116 is complemented with the turbine wheel 102, the complementary geometry allows for uniform tolerance stack-up, eliminating unwanted air gaps of a certain volume that cause unwanted air flow circulation and air accumulation within the turbocharger 100. The turbine end 116 can be formed with a complementary geometry to create an exit air gap 200 between the turbine end 116 and the turbine wheel 102 resulting from the tolerance stack-up after assembly to facilitate cooling of the turbine wheel 102 and the exhaust gas flow exiting the turbocharger 100. The exit air gap 200 allows cooling air to be effectively present between the turbine wheel 102 and the turbine end 116, allowing for the removal of a separate heat shield attached to the bearing housing 108. The turbine end 116 is machined or cast with the complementary geometry controlled to control the tolerance and clearance between the turbine end 116 and the turbine wheel 102. By controlling the tolerance and clearance between the turbine end 116 and the turbine wheel 102, cooling air is able to be present in the exit air gap 200, eliminating the need for a separate heat shield coupled to the bearing housing 108. The cooling air effectively present in the exit air gap 200 acts as a heat shield, improving the cooling of the turbine wheel 102 without the need for an auxiliary heat shield coupled to the bearing housing 108.

[0044] The turbine end 116 can be at least partially covered with a thermal barrier material, such as ceramic fiber, heat resistant fabric, metal foil, composite material, and thermal barrier coating (TBC). The thermal barrier material can include, for example, metal matrix composites such as aluminum matrix composites, titanium diboride, alumina, alumina-silica, boron nitride, silicon carbide, vitrium oxide, YSZ (yttrium stabilized zirconia), gadolinia, MCrAlY coating, plasma sprayed TBC, electron beam physical vapor deposition (EB-PVD) TBC, and zirconia.

[0045] If the operating temperatures within the turbocharger 100 become too high, the oil used to lubricate the plurality of bearings 112 can also be susceptible to cracking and coking. The turbocharger 100 can utilize the bearing housing 108 to limit the heat from the exhaust gas from flowing from the turbine wheel 102 to the compressor 104 within the bearing housing 108. The temperature range of the exhaust gas in an engine or generator can be 740°C to 1050°C, depending on the fuel used, such as gasoline, diesel, ethanol, etc.

[0046] Reference Figure 4According to one embodiment of the present application, air flow 202 is shown exiting bearing housing 108. By extending bearing housing 108 to turbine end 116 and forming turbine end 116 to the geometry of turbine wheel 102, undesirable air flow is prevented and avoided because the tolerance stack-up between bearing housing 108 and turbine wheel 102 after assembly creates less air gap and / or air accumulation. By extending bearing housing 108 to turbine end 116 and forming turbine end 116 to the geometry of turbine wheel 102, air flow 202 can exit turbocharger 100 with a more uniform flow, which can improve cooling of turbine wheel 102. Air flow 202 can be high pressure air that serves as a sealant to prevent oil from escaping bearing housing 108, while also providing cooling air to turbine wheel 102 and turbine end 116. The cooling air from air flow 202 in exit air gap 200 serves as a heat shield.

[0047] Air flow 202 in bearing housing 108 of turbocharger 100 is created by a combination of natural and forced convection. Natural convection is created as heated air rises, creating flow in at least one passage 204 within bearing housing 108. At least one passage 204 can be provided in bearing housing 108 to allow fluid communication with exit air gap 200 for exiting turbocharger 100. At least one passage 204 serves as an exit path from bearing housing 108 to exit air gap 200.

[0048] In one embodiment, at least one passage 204 can be distributed in any suitable manner, such as equi-spaced or unequally spaced circumferential slots. At least one passage 204 can extend through turbine end 116 or through a portion of bearing housing 108. At least one passage 204 can have various orientations, parallel, perpendicular, or at any suitable angle relative to the axis of shaft 106, as shown by line 2-2. At least one passage 204 can be optimized in multiple radial locations in order to achieve a desired pressure ratio. At least one passage 204 can be formed by casting and / or machining.

[0049] The air flow 202 directed by the at least one passage 204 toward the turbine wheel 102 can recirculate in a chamber 206 in the bearing housing 108. The chamber 206 can be formed when the bearing housing 108 is cast or machined. The air flow 202 of exhaust gas can enter the chamber 206 and flow toward the at least one passage 204 and / or the outlet air gap 200 where it exits the chamber 206. The recirculation of exhaust gas within the chamber 206 can promote air flow, turbulence and / or pressure within the bearing housing 108 for increasing the outlet flow. The increase in pressure can promote air flow between the turbine end 116 and the turbine wheel 102, thereby cooling the turbine wheel 102.

[0050] Reference is made to Figure 5 , which shows a cross-sectional view of a turbocharger 100 according to another embodiment of the present application. Figure 5 Reference is made to Figure 2 , which shows a turbine wheel 102 having a design variation according to another embodiment of the present application. This embodiment shows a variation of the cooling system, wherein the cross-drilling from each supply path is omitted. A heat shield 500 is secured to the main body 114 of the bearing housing 108 by fastening means, such as bolts 502. The main function of the heat shield 500 is to block the axial supply path outlets, thereby pressurizing the area behind the heat shield 500. This configuration directs the cooling air flow around the inner side end 506 of the heat shield 500, thereby ensuring uniform distribution of cooling air over the back wall of the turbine wheel 102 (originating from the outer diameter of the shaft 106).

[0051] The heat shield 500 acts as a barrier to prevent direct heat transfer and as a duct to direct cooling air to effectively surround its perimeter. Design considerations for the heat shield 500 include its material composition to withstand high thermal stresses and its geometric alignment with the turbine wheel 102 to promote optimal air flow.

[0052] The bolts 502 used to secure the heat shield 500 to the bearing housing 108 are designed for robust attachment, thereby ensuring the stability of the heat shield 500 in operation. The choice of material for the bolts 502 and their thread design are critical to maintain the structural integrity of the assembly under high speed rotational forces and thermal expansion.

[0053] Reference is made to Figure 5 and Figure 22including a labyrinth seal 510 and / or a ring seal 512 to improve the sealing efficiency between the shaft and the bore proximate the first end of the bearing housing. The labyrinth seal 510 located between the shaft and the bore includes a plurality of teeth arranged in a series of stages to create a tortuous path for air. This design minimizes the leakage of air and improves the sealing efficiency. The labyrinth seal 510 is strategically placed in the high pressure stage of the turbine where it effectively manages the pressure differential between the first volume 514 and the second volume 516. By utilizing a plurality of teeth, the labyrinth seal 510 ensures that any air attempting to bypass the seal is throttled and dissipated through each stage, significantly reducing overall leakage.

[0054] The ring seal 512, commonly referred to as a piston ring seal, is used in the low pressure stage of the turbine. This seal includes one or two piston rings that provide an additional sealing mechanism between the shaft and the bore. The ring seal 512 is designed to handle lower pressure differentials and supplements the function of the labyrinth seal 510 by providing an initial barrier that prevents air leakage. The ring seal 512 is located further downstream in the sealing arrangement, ensuring that any residual air that bypasses the labyrinth seal 510 is effectively sealed.

[0055] The combination of the labyrinth seal 510 and the ring seal 512 provides a robust sealing system for the radial turbine. The high pressure stage managed by the labyrinth seal 510 ensures minimal air leakage by creating multiple barriers for air to pass through. The subsequent ring seal 512 acts as a secondary sealing mechanism, providing additional security against any air that can bypass the labyrinth seal 510. This dual sealing method ensures optimal performance of the turbine by maintaining the required pressure differential between the first volume 514 and the second volume 516.

[0056] During operation, air is directed away from the labyrinth seal 510 from the first volume 514 around the heat shield, minimizing the amount of air passing through the seal and ensuring an efficient seal. The bearing housing design with a rounded edge at the first end further aids in directing air away from the sealing features, enhancing the longevity and efficiency of the labyrinth seal 510 and the ring seal 512.

[0057] By employing these advanced sealing techniques, the radial turbine achieves improved performance, reduced air leakage, and enhanced durability of the sealing components, contributing to the overall efficiency and reliability of the turbocharger system.

[0058] The heat shield 500 is attached to the main body of the bearing housing 108 and includes a portion disposed between the main body of the bearing housing 108 and the turbine wheel 102. The heat shield 500 has an opening coaxial with the shaft bore 110, allowing a portion of the shaft 106 to pass therethrough. The heat shield 500 defines a first volume 514 between the bearing housing 108 and the heat shield 102 and a second volume 516 between the heat shield 500 and the turbine wheel 102. The first volume 514 and the second volume 516 are in fluid communication through a radial gap 124 between a portion of the heat shield 500 and the shaft 106. The bearing housing 122 includes at least one cooling channel 508 that serves as at least one air passage in communication with the first volume 514. During operation, air flows from the at least one cooling channel 508 into the first volume 514 and then into the second volume 516. The air passage can include a flared portion 128 proximate the heat shield 500 where the cross-sectional area increases to a maximum.

[0059] The first end of the bearing housing 108 can include a recessed portion disposed radially outward of the bearing housing 108 and inward of the cooling channel 508. The recessed portion has a curved profile that increases the axial dimension of the bearing housing 108 toward the turbine wheel 102 with a reduced radial distance. Additionally, the first portion of the bearing housing 108 has a rounded cross-sectional profile at the opening 120. The heat shield 500 includes a first surface facing the first volume 514 and a second surface facing the second volume 516, with the rounded cross-sectional profile of the inboard end 506 defining a semicircular cross-section that connects the first surface and the second surface of the heat shield 500. Reference is made to Figure 22 , the interface 504 represents the area of overlap where the shaft 104 and the turbine wheel 102 are joined. The interface 504 is designed with an interference fit to ensure a tight joint. The components are friction welded to create a strong and reliable bond that can withstand high speed rotation and the significant forces encountered during operation. The interference fit and friction welding ensure that there is no relative movement between the shaft and the turbine wheel, maintaining alignment and enhancing the durability of the system.

[0060] Reference is made to Figure 6 , an enlarged view of the inboard end 506 is shown according to another embodiment of the present application. The profile of the inboard end 506 of the heat shield 500 is specifically configured to direct cooling air with minimal resistance, promoting an efficient flow path around the heat shield 500 and toward the cooling channel 508. The shape of the inboard end 506 is designed to ensure a smooth transition of the air flow, reducing turbulence and enhancing the cooling effect.

[0061] Cooling channels 508 are designed to distribute cooling air evenly across the back wall of turbine wheel 102. The configuration and orientation of these channels are critical to achieving uniform thermal gradients across turbine wheel 102, mitigating hot spots, and enhancing the life of the component.

[0062] Reference is now made to the following drawings, in which Figures 7-8 Figure 1 illustrates a turbine wheel 102 according to an embodiment of the present application. In Figure 7 and Figure 8 illustrate the overall shape of turbine wheel 102, showing that its aerodynamic profile is designed to efficiently convert exhaust gas energy into rotational energy. Turbine wheel 102 can include a plurality of blades, each designed to maximize the conversion of thermal and kinetic energy from the exhaust gas into mechanical energy. The geometric design of turbine wheel 102, including the curvature and angle of the blades, is performance-optimized over a wide range of operating conditions, balancing efficiency and durability.

[0063] While the following detailed description introduces example aspects in relation to a turbocharger, it should be understood that the description applies equally to the use of the present application in other applications, including but not limited to gasoline engines, diesel engines, intercooled and recuperated engines, rotary engines, gasoline combustion engines, and / or diesel engines used in various automobiles, cars, trucks, SUVs, CSUVs, sports vehicles, racing vehicles, and other similar power generators and vehicles.

[0064] In another embodiment, as shown in Figure 10 , a turbocharger 1100 includes a turbine wheel 1102, a compressor wheel 1104, and a shaft 1106 for rotatably coupling turbine wheel 1102 and compressor wheel 1104. Shaft 1106 extends through a center housing 1108. Turbine wheel 1102 can be located within a turbine housing, and compressor wheel 1104 can be located in a compressor housing, as is generally known in the art. Shaft 1106 can be disposed in a shaft bore 1110 in center housing 1108.

[0065] Turbine wheel 1102 can be rotationally driven by exhaust gases exiting turbocharger 1100. Rotation of turbine wheel 1102 is transmitted to compressor wheel 1104 by shaft 1106. Compressor wheel 1104 can be used to increase the pressure of intake air before it is mixed with fuel for combustion in an engine or generator. Rotation of turbine wheel 1102 creates a forced vortex, in which particle velocity and pressure vary proportionally with the radius of rotation.

[0066] Figure 11 An example embodiment of turbine wheel 1102 is schematically represented in a front view in Figure 12 , and schematically represented along a longitudinal axis of turbine wheel 1102 inFigure 11 FIG. 12 is a cross-sectional view taken along line 12-12. The turbine wheel 1102 can be formed by a casting process and can be attached at one end to the shaft 1106 by a shaft attachment area 1204. The turbine wheel 1102 can form a turbine wheel body 1202 having a back wall 1206 at an end of the turbine wheel body 1202 proximate the shaft attachment area 1204. As shown, the back wall 1206 of the turbine wheel 1102 is formed as a disk having a back wall end thickness ti. The turbine wheel 1102 can include a plurality of blades 1208 for interacting with exhaust gases from an engine and driving rotation of the shaft. Figures 12-13

[0067] Figure 13 FIG. 13 shows details of the turbine wheel 1102. Each of the plurality of blades 1208 can have a blade width 1210 representing a spacing between each of the plurality of blades 1208. The blade width 1210 can be constant, such that the plurality of blades 1208 are evenly spaced around the surface of the back wall 1206, or the blade width 1210 can vary between the plurality of blades 1208. When the turbine wheel 1102 is cast, the back wall 1206 and the plurality of blades 1208 can have a cast surface 1212 at a cast diameter 1214. The turbine wheel 1102 is located in an area having tight clearances. The casting tolerances can be high, and therefore, to form a uniform surface for the clearance turbine wheel 1102 as well as to provide a surface that is balanced and has minimal air resistance, the cast surface 1212 can be ground to a machined surface 1216 having a constant diameter represented by a machined diameter 1218. As a result of grinding the plurality of blades 1208, a blade area represented by the machined surface 1216 on each of the plurality of blades 1208 can be formed to have a blade diameter at the machined diameter 1218.

[0068] During the casting process, a scallop can be formed in the back wall 1206 of the turbine wheel 1102, as represented by a scallop area 1220. Figure 13 To provide a smooth transition between the scallop area 1220 and the blade area formed by the machined surface 1216, a transition area 1224 can also be provided at each end of the scallop area 1220 by a casting process as it transitions back into the blades of the plurality of blades 1208. The transition area can include a gradual rounding from the scallop area 1220 to the plurality of blades 1208. The transition area 1224 can also include a portion of the plurality of blades cast at a transition radius 1226 formed tangent to the scallop area 1220 at a scallop diameter 1222. Figure 19 ​This represents a fully machined turbine impeller 1102, which has a blade region, a fan-shaped region 1220, and a transition region 1224 connecting the two, formed by a machined surface 1216.

[0069] The sector region 1220 can have a constant diameter from the center of the turbine impeller 1102, represented by the sector diameter 1222. The sector diameter 1222 can be nominally smaller than the machining diameter 1218, causing the sector region 1220 to form a "mini-sector" that is the opposite of a conventional sector. For example, the sector diameter 1222 can be between 98% and 99.6% of the machining diameter 1218. Other percentages are, of course, also possible. In another example, the sector diameter 1222 can be nominally smaller than the machining diameter 1218 due to predetermined tolerances in the casting process. In this example, the machining diameter 1218 is predetermined, and the upper limit of the casting tolerance is set such that the sector diameter 1222 is always smaller than the machining diameter.

[0070] The sector region 1220 can be rounded with different contours so that multiple different embodiments of the turbine impeller 1102 can be formed. Figure 14 In the first embodiment, the sector region 1220 can be completely rounded, and the diameter of the sector region 1220's outline is equal to the rear wall end thickness t1. The rounding of the sector region 1220 can have a tangential transition with the two surfaces of the rear wall 1206. Figure 15 In the second embodiment shown, the fan-shaped region 1220 may have a fan-shaped profile with an elliptical profile, the elliptical profile including a tangential transition with the two surfaces of the rear wall 1206. Figure 16 In the third embodiment shown, the sector region 1220 may have a three-part sector profile. Figure 16 The profile of the fan-shaped region 1220 may include: a flat portion located at or near the fan diameter 1222, at or near the machined surface 1216; and a rounded portion having a radius at each end of the flat portion and forming a tangential transition to the flat portion and the front and rear surfaces of the rear wall 1206. Finally, in the... Figure 17 In the alternative embodiment shown, the sector profile may be defined by the free curve 1228. Other embodiments with different sector profiles of the sector region 1220 may also be implemented.

[0071] The following is for reference. Figures 19-20 According to one embodiment of the present invention, the figure illustrates Figure 10 A cross-sectional view of the turbocharger 1100 taken along line 19-19. (See image below.) Figure 19As shown, shaft 1106 can extend through center housing 1108 and be rotatably mounted within center housing 1108 in shaft bore 1110. Shaft 1106 can have a plurality of bearings 1112 mounted about shaft 1106. Plurality of bearings 1112 can include journal bearings and / or ball bearings as generally known in the art. Shaft 1106, turbine wheel 1102, and compressor wheel 1104 can rotate at very high speeds, for example, in excess of 250,000 rpm. To support high speed rotation, oil can be used to lubricate plurality of bearings 1112 for supporting shaft 1106.

[0072] As shown, in the region about turbine wheel 1102, center housing 1108 has a body 1114 that extends radially to turbine wheel 1102, has a turbine end 1116 that is formed with a geometry that is complementary to turbine wheel 1102. Turbine end 1116 can be formed in any suitable manner when forming center housing 1108, for example, by casting, machining, shot peening, etc. Turbine end 1116 extends in a generally radially outward direction (taken along line 20-20) relative to the rotational axis of shaft 1106. Turbine end 1116 faces turbine wheel 1102 and forms a geometry that faces compressor end 1118 of turbine wheel 1102 that faces compressor wheel 1104. Figures 12-13

[0073] Components within center housing 1108, for example, plurality of bearings 1112, are protected from unwanted heat energy transfer from exhaust gases in turbine wheel 1102 because turbine end 1116 prevents conduction and radiative heat flow from the exhaust gases through center housing 1108 back to compressor end 1118. By casting turbine end 1116 to the geometry of turbine wheel 1102, any adverse effects from temperature increases within turbocharger 1100 are avoided, heat is prevented from propagating toward compressor wheel 1104 and affecting components within turbocharger 1100. Turbine end 1116 also prevents heat from the exhaust gas flow to the seal ring, piston ring, and plurality of bearings 1112. Turbine end 1116 of center housing 1108 is a heat shield formed integrally with center housing 1108.

[0074] Turbine end 1116 can have various configurations as needed to complement the geometry of turbine wheel 1102. For example, center housing 1108 can have a generally disc-shaped structure (without a flange). When turbine end 1116 is complementary to turbine wheel 1102, the complementary geometry allows for uniform tolerance stacking, thereby eliminating unwanted air gaps of a certain volume that cause unwanted air flow circulation and air accumulation within turbocharger 1100.

[0075] ​The turbine end 1116 can be at least partially covered with a thermal barrier material, such as ceramic fiber, heat resistant fabric, metal foil, composite material, and thermal barrier coating (TBC). The thermal barrier material can include, for example, metal matrix composite (e.g., aluminum matrix composite), titanium diboride, alumina, alumina-silica, boron nitride, silicon carbide, vitreous oxide, YSZ (yttria-stabilized zirconia), gadolinia zirconate, MCrAlY coating, plasma sprayed TBC, electron beam physical vapor deposition (EB-PVD) TBC, and zirconia.

[0076] If the operating temperature within the turbocharger 1100 becomes too high, the oil used to lubricate the plurality of bearings 1112 can also be susceptible to cracking and coking. The turbocharger 1100 can use the center housing 1108 to limit the heat from the exhaust gas from flowing within the center housing 1108 from the turbine wheel 1102 to the compressor wheel 1104. The exhaust gas in an engine or generator can be in the temperature range of 740°C to 1050°C, depending on the fuel used, such as gasoline, diesel, ethanol, etc.

[0077] The turbine end 1116 can be formed with complementary geometry so that the outlet air gap 1300 (not shown) is formed by the tolerance stack-up between the turbine end 1116 and the turbine wheel 1102 after assembly to facilitate cooling of the turbine wheel 1102 and the exhaust gas flow exiting the turbocharger 1100. The outlet air gap 1300 allows cooling air to be effectively present between the turbine wheel 1102 and the turbine end 1116, thereby allowing the removal of a separate heat shield attached to the center housing 1108. The turbine end 1116 is machined or cast with the complementary geometry controlled so that the tolerance and clearance between the turbine end 1116 and the turbine wheel 1102 is controlled. By controlling the tolerance clearance between the turbine end 1116 and the turbine wheel 1102, cooling air can be achieved in the outlet air gap 1300, thereby eliminating the need to have a separate heat shield coupled to the turbocharger 1100. The cooling air effectively present in the outlet air gap 1300 acts as a heat shield, thereby improving the cooling of the turbine wheel 1102 without the need for an auxiliary heat shield coupled to the center housing 1108.

[0078] Reference Figure 20According to one embodiment of the invention, the figure illustrates an airflow 1302 exiting the central housing 1108. By extending the central housing 1108 to the turbine end 1116 and shaping the turbine end 1116 into the geometry of the turbine impeller 1102, undesirable airflow is prevented and avoided because the tolerance superposition formed between the central housing 1108 and the turbine impeller 1102 after assembly results in less air gap and / or air buildup. By extending the central housing 1108 to the turbine end 1116 and shaping the turbine end 1116 into the geometry of the turbine impeller 1102, the airflow 1302 can exit the turbocharger 1100 with a more uniform flow, which can improve the cooling of the turbine impeller 1102. The airflow 1302 can be high-pressure air, which acts as a sealant to prevent oil from escaping from the central housing 1108, while also providing cooling air for the turbine impeller 1102 and the turbine end 1116. Cooling air from the airflow 1302 in the outlet air gap 1300 is used as a thermal shield.

[0079] The airflow 1302 in the central housing 1108 of the turbocharger 1100 is formed by a combination of natural convection and forced convection. Natural convection occurs as heated air rises, thereby generating flow in at least one channel 1304 within the central housing 1108. The at least one channel 1304 may be provided in the central housing 1108 to allow fluid communication with the outlet air gap 1300 for exiting the turbocharger 1100. The at least one channel 1304 serves as an outlet path from the central housing 1108 to the outlet air gap 1300.

[0080] like Figure 20 As shown, the airflow 1302 can be directed to the rear of the turbine impeller 1102 and upward along the rear surface of the rear wall 1206. The airflow 1302 can be directed onto the rounded profile of the fan-shaped region 1220 between the multiple blades 1208. Then, the airflow 1302 can be directed onto the turbine impeller body 1202 of the turbine impeller 1102 and can help promote better cooling of the turbine impeller 1102.

[0081] In one embodiment, at least one channel 1304 can be distributed in any suitable manner, such as equally or unequally spaced circumferential slots. The at least one channel 1304 can extend through the turbine end 1116 or through a portion of the central housing 1108. The at least one channel 1304 can have various orientations, parallel, perpendicular, or at any suitable angle relative to the axis of shaft 1106, as shown by the 20-20 line. The at least one channel 1304 can be optimized in multiple radial positions to achieve an ideal pressure ratio. The at least one channel 1304 can be formed by casting and / or machining.

[0082] The flow of air 1302 directed by the at least one passage 1304 toward the turbine wheel 1102 can recirculate in a chamber 1306 within the center housing 1108. The chamber 1306 can be formed when the center housing 1108 is cast or machined. The flow of air 1302 of exhaust gas can enter the chamber 1306 and flow toward the at least one passage 1304 and / or the exit air gap 1200 where it exits the chamber 1306. The recirculation of exhaust gas within the chamber 1306 can promote air flow, turbulence, and / or pressure within the center housing 1108 for increasing exit flow. The increase in pressure can promote air flow between the turbine end 1116 and the turbine wheel 1102, thereby cooling the turbine wheel 1102.

[0083] Industrial Applicability

[0084] In operation, the present application can be applied in many industries, including but not limited to the power generation, energy, automotive, racing, and vehicle industries. In particular, the technology of the present application can be used in the internal combustion engines of generators and / or motor vehicles, including but not limited to generators, gasoline generators, diesel generators, intercooled and recuperated generators, gasoline engines, diesel engines, rotary engines, motors, and the like. Although the foregoing detailed description specifically refers to the internal combustion engine of a generator for an automobile, it should be understood that the teachings thereof can also be applied to other engines and motors, such as generators, automobiles, cars, trucks, SUVs, CSUVs, sports vehicles, racing vehicles, and other similar vehicles and machines, as well as other machines having an intake system or air induction system that utilizes a turbocharger.

[0085] Reference will now be made to Figure 9 FIG. 9 illustrates a method 900 of forming a bearing housing for a turbocharger in accordance with one embodiment of the present application. In step 902, a bearing housing 108 is cast, the bearing housing 108 having a main body with a turbine end 116 extending radially outwardly toward a turbine wheel 102. The turbine end 116 is formed to have a geometry complementary to the turbine wheel 102.

[0086] In step 904, at least one passage 204 is formed in the bearing housing 108 to allow fluid from outside the bearing housing 108, thereby forming an exit air gap 200 between the turbine end 116 and the turbine wheel 102.

[0087] The turbocharger 100 can be provided in a generator that uses two turbochargers 100 in series with a power turbine stage that can not have a compressor 104 or compressor stage. The power turbine stage can be directly connected with an alternator or generator. When provided in a generator, the generator combustor can feed exhaust gas directly to the turbocharger 100. The generator can be an intercooled and regenerative generator that uses two turbochargers 100 in series with a power turbine stage.

[0088] Reference is made below to Figure 21 FIG. 2, which illustrates a method of manufacturing a turbine wheel 1102 of the present application. In a first step 1402, the turbine wheel 1102 is cast as a turbine wheel body 1202 having a shaft attachment area 1204, a back wall 1206, and a plurality of blades 1208 extending from the turbine wheel body to a cast surface 1216 having a cast diameter 1214. The casting process forms a scalloped area 1220 between each of the plurality of blades 1208 having a profile represented by Figures 14-17 and a resulting constant diameter represented by a scalloped diameter 1222. The casting process also forms a transition area 1224 between the scalloped area 1220 and the plurality of blades 1208. The transition area 1224 is formed tangent to the scalloped diameter 1222 and has a transition radius 1226 to the plurality of blades 1208.

[0089] In a final step 1404, the cast surface 1212 on the plurality of blades 1208 is machined by grinding the plurality of blades 1208 down to a machined surface 1216 having a machined diameter 1218. The plurality of blades 1208 are held at the machined diameter 1218 and thus form a blade area, where the machined diameter 1218 is greater than the scalloped diameter 1222.

[0090] The turbine wheel 1102 provides a number of advantages over conventional turbine wheels. The scalloped area 1220 of the turbine wheel 1102 allows for lower rotational inertia and lower stresses in the back wall 1206 and is small enough to result in minimal or no loss of efficiency. Additionally, the rounding of the back wall 1206 including the scalloped area 1220 allows for greater airflow from the back of the turbine wheel 1102 into the exhaust gas path that interacts with the plurality of blades 1208. A cooling air flow that is directed through the rounded area of the scalloped area into the gap between the plurality of blades 1208 and the turbine wheel body 1202 can facilitate increased cooling of the turbine wheel 1102. The turbine wheel 1102 with cooling allows the turbocharger 1100 to operate at higher exhaust gas temperatures.

[0091] As can be seen from the foregoing, the technology disclosed herein has industrial applicability in a variety of devices, such as but not limited to turbochargers and bearing housings for engines and generators, and cooling system designs for turbochargers.

Claims

1. A radial turbine comprising: a radial turbine wheel attached on a shaft; a body comprising a first end and an opposite second end, wherein the body comprises a bore extending between the first end and the second end, the bore comprising a bearing arranged to support the shaft, at least a portion of the shaft being arranged in the bore, and the turbine wheel being arranged proximate the first end of the body; a thermal shield attached on the body, wherein the thermal shield comprises a portion arranged between the first end of the body and the turbine wheel, the thermal shield comprising an opening coaxial with the bore of the body such that a portion of the shaft is received in the opening, a first volume being defined between the first end of the bearing housing and the portion of the thermal shield, a second volume being defined between the portion of the thermal shield and the turbine wheel, the first volume and the second volume being in fluid communication through a radial gap between the portion of the thermal shield and the shaft; at least one air channel arranged in the bearing housing, wherein the at least one air channel terminates at the first end of the bearing housing and is in communication with the first volume, wherein, during operation, air flows from the at least one air channel into the first volume and then into the second volume.

2. The radial turbomachine of claim 1, wherein: a surface of the portion of the thermal shield facing the second volume has a cross-sectional shape complementary to a cross-sectional shape of a back wall of the turbine wheel.

3. The radial turbine of claim 1, further comprising: a turbine wheel body having a back wall proximate the shaft, the back wall formed as a disc having a back wall thickness; a plurality of blades formed in the turbine wheel body; a blade region in which each of the plurality of blades extends from the back wall, having a blade diameter measured from a center of the turbine wheel body; a sector region in the back wall formed as a rounded surface in a radially outermost surface of the back wall and having a sector diameter sized such that the sector diameter is as close as possible to the blade diameter radially inward of a grinding or milling tool at a set blade diameter; and a transition region from the sector region to the blade region formed tangential to the sector diameter and having a transition radius.

4. The radial turbomachine of claim 1, wherein: The at least one air channel comprises a flared portion proximate the first end of the bearing housing, a cross-sectional area of the air channel increasing to a maximum cross-sectional area at the first end of the bearing housing.

5. The radial turbomachine of claim 1, wherein: The first portion of the bearing housing comprises a rounded cross-sectional profile at the opening.

6. The radial turbomachine of claim 5, wherein: The portion of the thermal shield comprises a first surface facing the first volume and a second surface facing the second volume, and the rounded cross-sectional profile defines a semi-circular cross-sectional profile connecting the first surface and the second surface.

7. The radial turbomachine of claim 1, wherein: The first end of the bearing housing comprises a recessed portion arranged radially outward of the bore and radially inward of the at least one air channel, the recessed portion comprising a curved profile such that an axial dimension of the bearing housing toward the turbine wheel increases as the radial distance decreases.

8. The radial turbomachine of claim 7, wherein: The first portion of the bearing housing comprises a rounded cross-sectional profile at the opening, the portion of the heat shield comprises a first surface facing the first volume and a second surface facing the second volume, and the rounded cross-sectional profile defines a semi-circular cross-sectional profile connecting the first surface and the second surface.

9. The radial turbomachine of claim 1, further comprising: a seal disposed between the shaft and the bore and proximate the first end of the bearing housing.

10. The radial turbomachine of claim 9, wherein: The seal is at least one selected from the group consisting of a labyrinth seal and a piston ring.

11. The radial turbomachine of claim 1, wherein: The turbine end is covered with a thermal barrier coating made of a thermal barrier material selected from one of the following: a metal matrix composite, an aluminum matrix composite, titanium diboride, alumina, alumina-silica, boron nitride, silicon carbide, vitreous oxide, yttria stabilized zirconia, gadolinia zirconia, MCrAlY coating, a plasma sprayed thermal barrier coating, an electron beam physical vapor deposition (EB-PVD) thermal barrier coating, and zirconia.

12. A turbocharger system comprising: a bearing housing having a main body extending radially outwardly and forming a turbine end having a geometry complementary to a turbine wheel; a shaft rotatably mounted in a shaft bore in the bearing housing, the turbine wheel disposed at an end of the shaft proximate the turbine end; at least one air passage extending through the bearing housing to allow fluid communication with an exterior of the bearing housing; and a heat shield attached to the turbine end, wherein the heat shield includes a portion disposed between the turbine end and the turbine wheel, a first volume is defined between the turbine end and the heat shield, a second volume is defined between the heat shield and the turbine wheel, and the first volume and the second volume are in fluid communication through a radial gap between the heat shield and the shaft. The at least one air passage is disposed in the bearing housing, the at least one air passage terminates at the first end of the bearing housing and is in communication with the first volume, wherein, during operation, air flows from the at least one air passage into the first volume and then into the second volume.

13. The turbocharger system of claim 12, wherein:

14. The turbocharger system of claim 13, wherein: the surface of the portion of the heat shield facing the second volume has a cross-sectional shape complementary to a cross-sectional shape of a back wall of the turbine wheel; the at least one air passage includes a flared portion proximate the first end of the bearing housing, a cross-sectional area of the air passage increasing to a maximum cross-sectional area at the first end of the bearing housing; the first portion of the bearing housing comprises a rounded cross-sectional profile at the opening; and the first end of the bearing housing comprises a recessed portion disposed radially outward of the bore and radially inward of the at least one air passage, wherein the recessed portion comprises a curved profile such that an axial dimension of the bearing housing toward the turbine wheel increases as the radial distance decreases. The passage is selected from:

15. The turbocharger system of claim 9, wherein: The passage is a circumferential slot; The passage extends perpendicular to an axis of the shaft in the bearing housing; and The passage extends parallel to an axis of the shaft in the bearing housing. ​ 16. The turbocharger system of claim 12, further comprising: a seal disposed between the shaft and the bore and proximate the first end of the bearing housing.

17. A method of forming a bearing housing for a turbocharger, the method comprising: casting a bearing housing having a main body with a turbine end portion extending radially outwardly toward a turbine wheel, the turbine end portion having a geometry complementary to the turbine wheel; attaching a thermal shield to the bearing housing, the thermal shield including a portion disposed between the turbine end portion of the bearing housing and the turbine wheel, wherein the thermal shield includes an opening coaxial with the bore of the bearing housing such that a portion of the shaft is received in the opening; and forming at least one air passage in the bearing housing, wherein the at least one air passage terminates at the turbine end portion of the bearing housing and is in communication with a first volume defined between the turbine end portion of the bearing housing and the thermal shield and a second volume defined between the thermal shield and the turbine wheel, and during operation, air flows from the at least one air passage into the first volume and then into the second volume.

18. The method of claim 15, further comprising: forming the first volume and the second volume in fluid communication through a radial gap between the portion of the thermal shield and the shaft.

19. The method of claim 15, further comprising: forming a flared portion in the at least one air passage proximate the turbine end portion of the bearing housing, a cross-sectional area of the air passage increasing to a maximum cross-sectional area at the turbine end portion of the bearing housing; forming a recessed portion in the turbine end portion of the bearing housing disposed radially outward of the bore and radially inward of the at least one air passage, wherein the recessed portion includes a curved profile such that an axial dimension of the bearing housing toward the turbine wheel increases as the radial distance decreases; and forming the thermal shield having a first surface facing the first volume and a second surface facing the second volume, wherein the first surface has a cross-sectional shape complementary to a cross-sectional shape of a back wall of the turbine wheel.

20. The method of claim 16. further comprising: forming a seal disposed between the shaft and the bore and proximate the turbine end portion of the bearing housing, wherein the seal is at least one selected from a group consisting of a labyrinth seal and a piston ring.

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