Air bearing cooling path for compressor arrangement

Abstract

A turbomachine includes a rotating set with a turbine wheel. The turbomachine also includes a casing that houses the rotating set, where the casing defines a turbine outlet passage for exhausting air from the turbine wheel. The turbine outlet passage points in a downstream direction along an axis of the turbine outlet passage. The turbomachine includes an air bearing system with at least one bearing component that supports the rotating set for rotation relative to the casing. The air bearing system includes a bearing cooling path that is fluidly connected to the at least one bearing component and has a bearing air line outlet. The bearing air line outlet is fluidly connected to the turbine outlet passage and points in the downstream direction along the axis.

Description

[0001] Cross Reference to Related Applications

[0002] The following is a continuation-in-part of U.S. Patent Application Serial No. 16 / 889,967, filed June 2, 2020, the entire disclosure of which is incorporated by reference. TECHNICAL FIELD

[0003] The present disclosure relates generally to turbine sections of turbomachinery, and more particularly, to a compressor arrangement with an air bearing cooling path to an outlet of a turbine section exhaust flow path. BACKGROUND

[0004] Fuel cell systems and other machinery often include turbomachinery supercharging arrangements. For example, in the case of fuel systems, a fuel cell compressor arrangement can be included for compressing air before it is fed to a fuel cell stack. This can improve the operating efficiency of the fuel cell system.

[0005] However, conventional turbomachinery, such as fuel cell compressor arrangements, suffer from various deficiencies. For example, it can be difficult to incorporate an air bearing system (i.e., a plain bearing system, a journal bearing system, etc.) into a fuel cell compressor arrangement or other turbomachinery. In particular, it can be difficult to incorporate a fluid cooling system that provides a flow of cooling air to air bearing components without negatively impacting performance, manufacturing efficiency, etc.

[0006] Further, some fuel cell compressor arrangements include a turbine section that absorbs liquid water that is expelled from the fuel cell stack. The liquid water can impede operation of the turbine section, bearing system, etc. This can cause rotational surging of the rotating set, bearing overloading, and / or otherwise negatively impact the compressor arrangement.

[0007] Accordingly, it would be desirable to provide a turbomachinery, such as a fuel cell compressor arrangement, with an improved air bearing system. It would be desirable to provide a turbomachinery with an improved air bearing cooling system. It would also be desirable to provide a fuel cell compressor arrangement with increased water absorption capacity. Other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background. SUMMARY

[0008] In one embodiment, a turbomachine is disclosed that includes a rotating set with a turbine wheel and a housing that houses the rotating set. The housing defines a turbine outlet passage for exhaust from the turbine wheel. The turbine outlet passage points in a downstream direction along an axis of the turbine outlet passage. The turbomachine also includes an air bearing system with at least one bearing component that supports the rotating set for rotation relative to the housing. The air bearing system includes a bearing cooling path that is fluidly connected to the bearing component and has a bearing air conduit outlet. The bearing air conduit outlet is fluidly connected to the turbine outlet passage and points in the downstream direction along the axis.

[0009] In another embodiment, a method of manufacturing a turbomachine is disclosed. The method includes supporting a rotating set of the turbomachine within a housing with an air bearing system. The rotating set includes a turbine wheel. The housing defines a turbine outlet passage for exhaust from the turbine wheel. The turbine outlet passage points in a downstream direction along an axis of the turbine outlet passage. The method also includes fluidly connecting an air conduit outlet of a bearing cooling path of the air bearing system to the turbine outlet passage. The turbine outlet passage points in the downstream direction along the axis.

[0010] In another embodiment, a method of manufacturing a turbomachine is disclosed. The method includes supporting a rotating set of the turbomachine within a housing with an air bearing system. The rotating set includes a turbine wheel. The housing defines a turbine outlet passage for exhaust from the turbine wheel. The turbine outlet passage points in a downstream direction along an axis of the turbine outlet passage. The method also includes fluidly connecting an air conduit outlet of a bearing cooling path of the air bearing system to the turbine outlet passage. The turbine outlet passage points in the downstream direction along the axis. BRIEF DESCRIPTION OF DRAWINGS

[0011] The present disclosure will be described hereinafter with reference to the following drawings in which like numerals refer to like elements throughout and in which:

[0012] Figure 1 is a schematic diagram of a fuel cell system with a turbomachine according to an example embodiment of the present disclosure;

[0013] Figure 2 is Figure 1 is an isometric view of a portion of a turbine section of the turbomachine of

[0014] Figure 3 is a schematic diagram of a fuel cell system with a turbomachine according to an example embodiment of the present disclosure;Figure 2 A cross-sectional view of the turbine section;

[0015] Figure 4 According to the example embodiment Figure 2 A cross-sectional view of the turbine section;

[0016] Figure 5 According to the example embodiment Figure 2 A cross-sectional view of the turbine section; and

[0017] Figure 6 According to the example embodiment Figure 2 A cross-sectional view of the turbine section. Detailed Implementation

[0018] The following detailed description is exemplary in nature only and is not intended to limit this disclosure or its application and use. Furthermore, there is no intention to be bound by any theories set forth in the foregoing background or the following detailed description.

[0019] In a broad sense, the exemplary embodiments disclosed herein include turbines, such as turbocompressor units. In some embodiments, the turbine may be a fuel cell compressor unit with a turbine section that receives exhaust gas from a fuel cell stack to drive a turbine impeller. The turbine section may also include a turbine outlet passage for guiding the exhaust gas flow from the turbine impeller. Furthermore, the turbine may include an air bearing system with an air bearing cooling path that provides airflow to one or more bearing components for cooling purposes and for supporting the rotation of the turbine's rotating assembly within a housing. The air bearing cooling path may include an air duct outlet fluidly connected to the turbine outlet passage. This air duct outlet may be axially oriented downstream. Thus, the air bearing system can be effectively cooled and firmly supported by the air flowing through the bearing cooling path. Similarly, this air can be directly output to the turbine outlet passage without negatively impacting the aerodynamic performance of the turbine section. Additionally, in some embodiments, the turbine may operate under conditions where the high-pressure exhaust gas flow reaching the turbine section contains moisture, liquid water droplets, water columns, etc. The axially oriented outlet of the bearing air duct outlet can provide protection against water intrusion into the bearing cooling path in the upstream direction.

[0020] Additional example embodiments of the present disclosure include a turbine section (i.e., turbine stage) of a turbomachine that provides certain operational benefits thereto. In some embodiments, a housing at the turbine section defines a circumferential flow passage (e.g., an annular passage, a volute passage, etc.) and an outlet. The turbine section can also include a turbine wheel arranged along a first flowpath for at least one fluid between the circumferential flow passage and the outlet. The housing can also define a recirculation flowpath that allows recirculation of the at least one fluid. The recirculation flowpath can include a recirculation flow passage that fluidly connects an upstream region of the turbine wheel of the first flowpath back to the circumferential inlet passage. Thus, fluid (e.g., liquid water) within the upstream region of the turbine wheel can be recirculated back into the circumferential inlet passage rather than continuing along the first flowpath and across the turbine wheel. As a result, rotation of the turbine wheel is less likely to be affected by such fluid. For example, when used in a fuel cell system, the turbine section / stage of the present disclosure has improved water absorption capabilities.

[0021] Further, the housing can define a bearing air conduit outlet, a circumferential flow passage, a turbine outlet passage, and a surface opposite the blades of the turbine wheel. The bearing air conduit outlet can extend through the housing and across the turbine section. Moreover, the bearing air conduit outlet can extend above (i.e., can be arranged radially outward of) the circumferential flow passage to fluidly connect a bearing component of the air bearing system to the turbine outlet passage. Further, the housing can include an internal radial lip that separates the air conduit outlet from the turbine outlet. The internal radial lip can direct the air conduit outlet in an axial and downstream direction along the turbine outlet. The internal radial lip can also act as a barrier to prevent moisture, liquid water, droplets, etc. from invading the air bearing cooling path in an upstream direction.

[0022] Referring first to Figure 1 A turbomachine 101 is shown in accordance with example embodiments. As shown, the turbomachine 101 generally includes a housing 119 (shown schematically) and a rotating set 118 supported by one or more bearings 121 for rotation within the housing 119 about a rotational axis 120. In some embodiments, the rotating set 118 and the housing 119 can collectively define a compressor section 110 (i.e., compressor stage) and a turbine section 113 (i.e., turbine stage). Moreover, a motor section 112 can be arranged axially between the compressor section 110 and the turbine section 113.

[0023] The rotating set 118 can generally include a shaft 149 that extends axially through the compressor section 110, the turbine section 113, and the motor section 112. The rotating set 118 can also include a compressor wheel 130 and a turbine wheel 131 attached to opposite ends of the shaft 149.

[0024] The bearing 121 of the turbine 101 supports the rotating assembly 118 for rotation within the housing 119. The bearing 121 can have various configurations without departing from the scope of this disclosure. In the illustrated embodiment, the bearing 121 is an air bearing (i.e., an air bearing system). However, it should be understood that the bearing 121 may include rolling elements or may be otherwise constructed. The bearing 121 also includes oil-lubricated journal bearings of various configurations (e.g., fully floating, semi-floating, split, coupled, etc.). Furthermore, in some embodiments, the bearing 121 may include an oil-lubricated rolling element bearing.

[0025] like Figure 1 As shown, bearing 121 can be an air bearing system (sliding bearing, journal bearing, etc.) having a first journal member 123, a second journal member 125, and a thrust bearing member 127. The first journal member 123 and the second journal member 125 may be axially spaced apart on opposite sides of the motor 134. The thrust bearing member 127 may be axially arranged between the compressor impeller 130 and the first journal member 123.

[0026] The bearing 121 (air bearing system) may also include at least one bearing cooling path 140. At least a portion of the cooling path 140 may extend through the housing 119 to direct air to one or more components of the bearing 121 for cooling purposes and for supporting the rotation of the rotating assembly 118, as will be discussed. More specifically, air may be delivered via the cooling path 140 to the thrust bearing member 127 to provide an air cooling film on both axial planes, thereby supporting thrust loads during operation. Furthermore, air may be delivered via the cooling path 140 to the first journal member 123 and / or the second journal member 125 to provide an air cooling film in the radial space therein, thereby supporting radial loads during operation.

[0027] Turbine 101 can be operatively connected to fuel cell system 100 and can be configured as an e-charger or electric compressor unit for fuel cell system 100. Fuel cell system 100 may include fuel cell stack 104 comprising multiple fuel cells. Hydrogen can be supplied from tank 106 to fuel cell stack 104, and oxygen can be supplied to fuel cell stack 104 to generate electricity through known chemical reactions. Fuel cell stack 104 can generate electricity for electrical devices such as electric motor 105. In some embodiments, fuel cell system 100 may be included in a vehicle, such as a car, truck, SUV, van, motorcycle, etc. Thus, in some embodiments, electric motor 105 can convert electrical energy into mechanical power to drive the axles (and therefore one or more wheels) of the vehicle and cause them to rotate.

[0028] Oxygen can be provided to the fuel cell stack 104 at least in part by the turbine 101. More specifically, the motor section 112 can drive rotation of the rotating set 118, the compressor section 110 can provide a compressed air stream (indicated by arrow 124) to the intercooler 128 as the compressed air stream flows to the stack 104, and an exhaust stream 132 from the stack 104 can be fed back to the turbine section 113, which in turn provides mechanical power assistance to the motor section 112.

[0029] The various components of the fuel cell system 100 and / or the turbine 101 can be controlled by a control system 135. The control system 135 can be a computerized system with a processor, various sensors, and other components for electrically controlling these operations. In some embodiments, the control system 135 can define or be part of an electrical control unit (ECU) of a vehicle.

[0030] It should be appreciated, however, that other configurations of the turbine 101 fall within the scope of the present disclosure. For example, the turbine 101 of the present disclosure can be provided in other systems (i.e., other than a fuel cell system). Moreover, features of the turbine section 113 can be included in a turbocharger or other turbine without departing from the scope of the present disclosure.

[0031] Reference is now made to Figures 1-3 The housing 119 of the turbine 101 will be discussed in greater detail in accordance with example embodiments. As Figure 1 Illustratively, the housing 119 of the turbine 101 can include a compressor housing 152, a motor housing 150, and a turbine housing 188. The compressor housing 152 can define a portion of the compressor section 110, the motor housing 150 can define a portion of the motor section 112, and the turbine housing 188 can define a portion of the turbine section 113. These portions of the housing 119 can be assembled together as detailed below to collectively house and support the rotating set 118.

[0032] In some embodiments, the compressor housing 152 can be a one-piece integral arc-shaped piece made of metal. The compressor housing 152 can define an inlet 153 extending along and centered on the axis 120. The compressor housing 152 can also include a convex compressor shroud surface 141 positioned in a downstream direction from the inlet 153. The compressor housing 152 can also include a volute passage 154 extending around the axis 120. The compressor housing 152 can be secured to one axial face of the motor housing 150 to cover the face of the compressor impeller 130 of the rotating set 118. The shroud surface 141 can be opposite the compressor impeller 130 and can have an inverse profile with respect to the compressor impeller. The inlet 153 can be fluidly connected to an external space (i.e., the environment) or can be fluidly connected to an upstream compressor device to receive a flow of air. The volute passage 154 can be fluidly connected to the intercooler 128 to provide a flow of compressed air 124 thereto.

[0033] The motor housing 150 can include one or more portions that define a cavity 151 for receiving and housing one or more portions of the motor 134 (e.g., an electric motor). In some embodiments, the motor housing 150 can house and support the motor stator member 138 within the cavity 151, while the motor rotor member 136 can be supported on the shaft 149 of the rotating set 118. As shown, the stator member 138 can be circumferentially surrounded by the motor rotor member 136 around the axis 120; however, in other embodiments, the rotor member 136 can surround the stator member 138.

[0034] The turbine housing 188 can include an outer turbine housing 195. In some embodiments, the outer turbine housing 195 can be a hollow and one-piece integral arc-shaped piece made of metal. The outer turbine housing 195 can include an outer radial portion 160 and an inner radial portion 162. The outer radial portion 160 and the inner radial portion 162 can include walls or other barrier structures that axially protrude from axial end portions 164 of the outer turbine housing 195. The outer radial portion 160 and the inner radial portion 162 can be spaced apart in a radial direction.

[0035] The inner radial portion 162 can be arcuate (e.g., annular), tubular, or hollow. The inner radial portion 162 may include an arcuate axial end 166. The end 166 may be radially outwardly profiled and may define a convex turbine shroud surface 189 thereon. The turbine shroud surface 189 may cover and oppose the outer edge of the blades of the turbine impeller 131. The inner radial portion 162 may also define an outlet passage 194 extending along axis 120 and centered on axis 120. The outlet passage 194 may be defined by a plurality of pipe segments arranged in series along axis 120 and having different widths (e.g., different diameters, radii, etc.). The outlet passage 194 may be defined by a first turbine exhaust pipe segment 142 projecting axially from the axial end portion 164 in one direction. The outlet passage 194 may be further defined by a second turbine exhaust pipe segment 143 projecting axially from the axial end portion 164 in the opposite direction. The first turbine exhaust pipe section 142 may have a first inner diameter 144, while the second turbine exhaust pipe section may have a second inner diameter 145. The second inner diameter 145 may be larger than the first inner diameter 144. The first turbine exhaust pipe section 142 and the second turbine exhaust pipe section 143 may be straight in the axial direction and may be arranged in series axially with the axis 120 as the center and the second turbine exhaust pipe section 143 arranged downstream of the first turbine exhaust pipe section 142. Therefore, the exhaust flow 132 may flow through the turbine impeller 131, through the first turbine exhaust pipe section 142, and then through the second turbine exhaust pipe section 143 to exit the turbine section 113.

[0036] like Figure 1 As shown, the outer turbine housing 195 may further include at least one bearing air duct outlet 196. The bearing air duct outlet 196 may be a fluid passage for the bearing cooling path 140. The bearing air duct outlet 196 may extend through the outer turbine housing 195 to fluidly connect one or more components of the bearing 121 to the outlet passage 194. Therefore, air may be supplied via the bearing cooling path 140 to the thrust bearing member 127, the first journal member 123, and / or the second journal member 125, and this air may further flow downstream through the bearing air duct outlet 196 of the outer turbine housing 195.

[0037] The bearing air outlet 196 may be an elongated channel, fluid conduit, hose, etc., with an upstream end 146 and a downstream end 147. The bearing air outlet 196 may be non-linear and curved as it extends from the upstream end 146 to the downstream end 147.

[0038] The upstream end 146 may be located at or adjacent to the motor housing 150. The upstream end 146 may be fluidly connected via the bearing cooling path 140 to the thrust bearing member 127, the first journal bearing member 123 and / or the second journal bearing member 125 to receive airflow therefrom.

[0039] The bearing air conduit outlet 196 can further include an axial segment 148 extending axially from the upstream end 146 in the downstream direction (i.e., along the axis 120 but radially spaced therefrom). The outlet 196 can further include a radially extending segment 155 extending radially inward from the axial segment 148 in the downstream direction toward the axis 120.

[0040] Further, the bearing air conduit outlet 196 can include a downstream terminal end 147. The downstream terminal end 147 can be axially curved from the radially extending segment 155 and can be disposed at and fluidly connected to the turbine outlet passage 194. The downstream terminal end 147 can be directed in the downstream direction along the axis 120. The downstream terminal end 147 can define an outlet axis 159 that is axially aligned with the axis 120. Figure 1 The downstream terminal end 147 is shown in FIG. 1 1 to illustrate that it is axially directed in the downstream direction from the turbine wheel 131 along the axis 120. The downstream terminal end 147 can be at least partially defined by a downstream-directed lip 158. The lip 158 can be an annular extension of the first turbine exhaust conduit segment 142. Thus, the lip 158 can be disposed at a transition between the first turbine exhaust conduit segment 142 and the second turbine exhaust conduit segment 143. The lip 158 can radially separate the bearing air conduit outlet 196 from the turbine outlet passage 194.

[0041] An outer radial portion 160 of the outer turbine housing 195 can be fixed to an axial face of the motor housing 150 on an axial side opposite the compressor housing 152. Thus, the outer turbine housing 195 can overlie a front face of the turbine wheel 131 of the rotating set 118. The turbine shroud surface 189 can oppose the turbine wheel 131 and can have an inverse profile with respect thereto.

[0042] The turbine housing 188 can further include an inner turbine housing structure 197. The inner turbine housing structure 197 can be a unitary member made of metal. The inner turbine housing structure 197 can include a back plate 198 and a nozzle structure 199. The back plate 198 can be relatively flat and can extend generally perpendicular to the axis 120 to overlie a back face of the turbine wheel 131. The nozzle structure 199 can be arcuate to extend at least partially about the axis 120. In some embodiments, the nozzle structure 199 can be annular and ring-like (as shown in FIG. 1 1). Figure 2 The nozzle structure 199 can also be fixed to the back plate 198 and can axially project away therefrom and can terminate at an axial end 191. The nozzle structure 199 can include a plurality of nozzle holes 176 extending generally radially therethrough. In some embodiments, the nozzle holes 176 can each be circular through holes with an axis directed radially and generally toward the turbine wheel 131. Also, as shown in FIG. 1 1, the nozzle holes 176 can be arranged in a uniformly spaced arrangement about the axis 120. Further, as shown in FIG. 1 1, the nozzle holes 176 can be arranged in a circumferentially extending row. Figure 2 The turbine housing 188 can further include a turbine shroud 189. The turbine shroud 189 can be a unitary member made of metal. The turbine shroud 189 can be annular and ring-like (as shown in FIG. 1 1) and can extend about the axis 120. The turbine shroud 189 can be fixed to the outer turbine housing 195 and can axially project away therefrom and can terminate at an axial end 192. The turbine shroud 189 can include a plurality of turbine shroud holes 177 extending generally radially therethrough. In some embodiments, the turbine shroud holes 177 can each be circular through holes with an axis directed radially and generally toward the turbine wheel 131. Also, as shown in FIG. 1 1, the turbine shroud holes 177 can be arranged in a uniformly spaced arrangement about the axis 120. Further, as shown in FIG. 1 1, the turbine shroud holes 177 can be arranged in a circumferentially extending row.Figure 2 and 3 As shown, axial end 191 of nozzle structure 199 can include a blocking portion 178. Blocking portion 178 can be a circular flange that projects radially outwardly and extends continuously in the circumferential direction around axis 120.

[0043] As shown, Figure 1 and 3 As shown, inner turbine housing structure 197 can be attached to outer turbine housing 195 and motor housing 150. An outer radial portion of backplate 198 can be disposed axially between outer turbine housing 195 and motor housing 150. Shaft 149 can extend through a central portion of backplate 198, and nozzle structure 199 can surround turbine wheel 131. Also, axial end 191 of nozzle structure 199 can mate with arcuate end 166 of outer turbine housing 195. It will be appreciated by those of ordinary skill in the art that the term "mate" will be interpreted broadly in this context. Opposing surfaces of ends 191, 166 can be shaped in a corresponding manner and disposed in close proximity to define a mating interface. These surfaces can or can not be physically connected to be considered mated together. In some embodiments, a sealing member can be included between these opposing surfaces, but such a sealing member can be omitted in some embodiments discussed in detail below. In some embodiments, ends 191, 166 can establish a male-female interface, in which arcuate end 166 is received within axial end 191 of nozzle structure 199. In some embodiments, outer radial surface 170 of arcuate end 166 can oppose inner radial surface 172 of axial end 191 of nozzle structure 199 radially. This interface will be discussed in greater detail below in accordance with various embodiments of the present disclosure.

[0044] When assembled together, outer turbine housing 195 and inner turbine housing structure 197 can collectively define at least a portion of a circumferential inlet passage 192 that extends around axis 120. Inlet passage 192 can be radially defined between outer radial portion 160 and inner radial portion 162 of outer turbine housing 195 and between outer radial portion 160 and nozzle structure 199. Inlet passage 192 can be axially defined between backplate 198 and axial end portion 164. As shown, Figure 1 Passage 192 can be an annular passage with a cross-sectional area that remains substantially constant as passage 192 extends around axis 120. In other embodiments, passage 192 can be a volute passage, in which the cross-sectional area gradually changes as it extends around axis 120. In some embodiments, passage 192 can also extend helically around axis 120.

[0045] Also, as shown, Figure 1As shown, the bearing air duct outlet 196 can be arranged radially outward from the channel 192 relative to the axis 120. Cooling airflow can flow to the air bearing 121 and can exit directly to the turbine outlet channel 194 via the bearing air duct outlet 196. The downstream end 147 of the outlet 196 can be axially oriented, while the lip 158 extends axially in the downstream direction. Therefore, the airflow from the outlet 196 merging with the turbine outlet channel 194 is unlikely to affect the aerodynamic performance of the turbine section 113. Furthermore, if moisture, water, droplets, etc., are present in the exhaust flow passing through the turbine outlet channel 194 (e.g., under low-speed exhaust flow conditions), the lip 158 can act as a barrier against the intrusion of water, moisture, etc., into the bearing air duct outlet 196.

[0046] Furthermore, the outer turbine casing 195, the inner turbine casing structure 197, and the turbine impeller 131 can jointly define the upstream region 174 of the turbine impeller. Figure 3 The upstream region 174 of the turbine impeller can be radially defined between the nozzle structure 199 and the upstream portion 129 of the turbine impeller 131 (e.g., the leading edge of the blades of the impeller 131). The upstream region 174 of the turbine impeller can be axially defined between the axial end 166 of the outer turbine housing 195 and the upstream portion 129 of the turbine impeller 131.

[0047] It should be understood that the nozzle structure 199 is an optional feature of this disclosure. Thus, in these embodiments, the outer radial portion of the upstream region 174 of the turbine impeller can access the circumferential inlet passage 192 (i.e., unobstructed by the nozzle structure or other similar structures).

[0048] like Figure 1 As shown, the circumferential inlet passage 192 can be fluidly connected to the fuel cell stack 104 to receive exhaust flow 132 from it. The turbine section 113 can define a first flow path for the exhaust flow 132 (by... Figure 1 (Indicated by arrow 180). Specifically, fluid in the first flow path 180 can flow downstream from the inlet channel 192, through the nozzle orifice 176, into the upstream region 174 of the turbine impeller, across the turbine impeller 131 and the shroud surface 189, and into the outlet channel 194 to exit the turbine 101. This fluid flow can drive the turbine impeller 131 to rotate to provide mechanical power to the rotating assembly 118.

[0049] Overall, during the operation of turbine 101, the inlet airflow (by...) Figure 1downstream into the volute passage 154, the inlet air stream 122 can be compressed. The compressed air stream 124 can exit the volute passage 154 and can be directed to the intercooler 128 and then to the fuel cell stack 104 to improve the operational efficiency of the fuel cell system 100. Further, as noted above, the exhaust stream 132 from the fuel cell stack 104 can be directed back toward the turbine 101 and received by the passage 192 of the turbine section 113. The high pressure exhaust stream 132 can be directed generally toward the turbine wheel 131 to drive rotation of the turbine wheel 131, and the low pressure exhaust stream can exit via the outlet passage 194. The mechanical power from the turbine section 113 can be converted to electrical power for the motor 134 to ultimately assist in rotation of the compressor wheel 130.

[0050] For example, as shown in Figure 3 The turbine section 113 can further include a recirculation flowpath 182. The recirculation flowpath 182 can extend from the circumferential inlet passage 192, through the turbine wheel upstream region 174, and back to the circumferential inlet passage 192. Thus, as will be discussed, fluids (e.g., liquid water entrained within the exhaust stream 132) can be circulated through the flowpath 182 without affecting rotation of the turbine wheel 131.

[0051] The recirculation flowpath 182 can be defined, at least in part, by one or more recirculation passages 184 that fluidly connect the turbine wheel upstream region 174 with the circumferential inlet passage 192. In some embodiments, as represented by Figure 2 and 3 The recirculation passages 184 can be defined, at least in part, by a radial gap between the outer radial surface 170 and the inner radial surface 172. Further, in some embodiments, the recirculation passages 184 can be defined by one or more axial bores 486 that extend axially through the outer turbine housing 195. The axial bores 486 are shown in dashed line in Figure 2 and will be discussed in greater detail below with reference to Figure 6 It should be appreciated that the recirculation passages 184 can have other configurations without departing from the scope of the present disclosure. Further, it should be appreciated that the recirculation passages 184 can include a combination of features (e.g., both a radial gap between the surfaces 170, 172 and axial bores 486) without departing from the scope of the present disclosure.

[0052] As noted above, in Figure 3In embodiments of the first aspect, the recirculation passage 184 can be defined by a radial gap between the outer radial surface 170 and the inner radial surface 172. This gap can extend continuously and annularly about the axis 120. Also, in some embodiments, at least one of the outer radial surface 170 and the inner radial surface 172 can include a recess that extends arcuately about the axis 120. For example, at least one of the surfaces 170, 172 can include an arcuate groove 168. For example, in the illustrated embodiment, the outer radial surface 170 includes the groove 168. The arcuate groove 168 can have a rectangular cross-section as shown and can have a groove depth 167 (measured radially) and a groove width 165 (measured axially). The groove 168 can also be axially centered on the radial outer surface 170. Figure 3

[0053] Accordingly, the exhaust stream 132 can include a combination of gas (air) and liquid (water) that is received within the circumferential inlet passage 192. This fluid combination can flow through the nozzle hole 176 to be received within the turbine wheel upstream region 174. The pressure build-up within the turbine wheel upstream region 174 can cause the gaseous portion of this combination (air) to continue along the first flow path 180 to the outlet passage 194 and can cause the liquid portion (water) to move along the recirculation flow path 182 into the recirculation passage 184, back to the circumferential inlet passage 192.

[0054] The recirculation flow path 182 can increase the water handling capacity of the turbomachine 101. The liquid recirculation provided by the flow path 182 can reduce the impact of liquid on the rotation of the turbine wheel 131. For example, at least some of the liquid that enters the turbine wheel upstream region 174 can be recirculated one or more times within the recirculation flow path 182, rather than flowing directly through the turbine wheel 131. In other words, the recirculation flow path 182 can reduce the instantaneous liquid flow rate along the first flow path 180. Accordingly, the liquid in the first flow path 180 is less likely to exert a braking force on the turbine wheel 131 to reduce rotational speed, thereby providing for efficient operation of the turbomachine 101. Also, the likelihood of surging rotation of the turbine wheel 131 is less because the liquid load on the wheel 131 can be reduced, can be more balanced, etc. Furthermore, the load on the bearing 121 can be reduced and the service life of the turbomachine 101 can be extended.

[0055] Figure 4 Another embodiment is shown and can be substantially similar to the embodiment of Figure 3 except as noted. Components corresponding to those of Figure 3 the embodiment of FIGS. 1-7 are indicated by corresponding reference numbers increased by 100. As shown, the passage 284 of the recirculation flow path 282 can be defined by an unsealed radial gap between the outer radial surface 270 and the inner radial surface 272. The cross-sectional shape of the groove 268 can be similar to that of the groove 168 of the embodiment of FIGS. 1-7. Figure 3 ​embodiments are rectangular, but the depth 267 of the recess 268 can be greater than Figure 3 the depth shown, and the width 265 of the recess 268 can be less than Figure 3 the width shown. Additionally, the block 278 of the nozzle structure 299 can be greater than Figure 3 the block shown, such that the block 278 protrudes radially outward to a greater dimension.

[0056] Figure 5 additional embodiments are shown, in which the components corresponding to Figure 3 those shown are indicated by the respective reference numbers increased by 200. As shown, the passage 384 of the recirculation flowpath 382 can be defined by an unsealed radial gap between the outer radial surface 370 and the inner radial surface 372. The cross-sectional shape of the recess 368 can be similar to Figure 3 embodiments are rectangular, except that the depth 367 of the recess 368 can be less than Figure 3 the depth shown, and the width 365 of the recess 368 can be greater than Figure 3 the width shown. Further, as Figure 5 shown, the nozzle structure 399 can be“blockless,” such that the nozzle structure 399 protrudes at a generally constant diameter until it terminates proximate the axial end 366 of the outer turbine housing 395.

[0057] It will be appreciated that the dimensions (e.g., depth and / or width) of the recesses 168, 268, 368 can be predetermined, selected, and configured such that the recirculation passages 184, 284, 384 provide desired flow characteristics for the liquid to recirculate. Further, the dimensions of the block 178, 278 can be selected to provide desired flow characteristics from the inlet passage 192, 292, 392 toward the nozzle structure 199, 299, 399, or the block can be omitted to provide desired flow characteristics as Figure 5 shown. It will also be appreciated that other dimensions and features of the passages 184, 284, 384 can be selected to provide desired flow characteristics.

[0058] Reference will now be made to Figure 2 and 6 additional embodiments will be discussed. Components corresponding to Figure 3 those shown are indicated by the respective reference numbers increased by 300. As shown, the passage 484 of the recirculation flowpath 482 can be collectively defined by a plurality of axial holes 486. At least one hole 486 can be a circular through-hole that is straight in the axial direction and extends through the axial end 466 of the outer turbine housing 495. At least one hole 486 can extend substantially parallel to the longitudinal axis and can have a generally constant width (diameter). There can be any number of axial holes 486 (e.g., a total of six), and as Figure 2As shown, the holes 486 can be generally equidistantly spaced in the circumferential direction. In some embodiments, the upstream ends 475 of the holes 486 can be disposed upstream of the shroud surface 489 and upstream of the turbine wheel 431 and can open into the turbine wheel upstream region 474. The downstream ends 477 of the holes 486 can be axially aligned with the upstream ends 475 and can open into the circumferential inlet passage 492. In some embodiments, the outer radial surface 470 and the inner radial surface 472 can be smooth and ungrooved, rather than including the annular grooves discussed above and shown in FIGS. 1-3. Thus, the holes 486 can primarily define the recirculation flow passage 484; however, in other embodiments, the gaps between the holes 486 and the radial surfaces 470, 472 can collectively define the recirculation flow passage 484. Figure 4 and Figure 5 As shown, the holes 486 can be generally equidistantly spaced in the circumferential direction. In some embodiments, the upstream ends 475 of the holes 486 can be disposed upstream of the shroud surface 489 and upstream of the turbine wheel 431 and can open into the turbine wheel upstream region 474. The downstream ends 477 of the holes 486 can be axially aligned with the upstream ends 475 and can open into the circumferential inlet passage 492. In some embodiments, the outer radial surface 470 and the inner radial surface 472 can be smooth and ungrooved, rather than including the annular grooves discussed above and shown in FIGS. 1-3. Thus, the holes 486 can primarily define the recirculation flow passage 484; however, in other embodiments, the gaps between the holes 486 and the radial surfaces 470, 472 can collectively define the recirculation flow passage 484.

[0059] In summary, the turbomachine 101 of the present disclosure can include a variety of configurations of recirculation flow paths 182, 282, 382, 482. The flow paths 182, 282, 382, 482 increase the ability of the turbomachine 101 to ingest water or other fluids. Moreover, the bearing cooling path can exit into the turbine exhaust flow path and can be axially directed in a downstream direction. Thus, the bearing cooling path can be incorporated without negatively impacting the aerodynamic performance of the turbine stage. Moreover, the axially directed exit of the bearing air conduit exit can provide protection from water ingress into the bearing cooling path in an upstream direction.

[0060] The turbomachine 101 can also be efficiently manufactured. In particular, the housing 119 at the turbine stage 113 can be attached together in relatively few steps and can have a relatively low part count. In some embodiments of the manufacture, the backplate 198 of the inner turbine housing structure 197 can be layered onto the motor housing 150 with one or more seals therebetween. The turbine wheel 131 can also be disposed within the nozzle structure 199. The outer turbine housing 195 can then be attached to the backplate 198 and / or the motor housing 150 by one or more fasteners, with the end 166 received within the nozzle structure 199. Thus, the features of the turbine stage 113 including the recirculation flow paths 182, 282, 382, 482 can be provided. Moreover, the turbine housing 195 can be efficiently manufactured to include the bearing cooling path exit 196.

[0061] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or embodiments described are only examples, and are not intended to limit the scope, applicability or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the disclosure. It should be understood that various changes can be made in the function and arrangement of elements described in the exemplary embodiment without departing from the scope of the disclosure as set forth in the appended claims.

Claims

1. A turbomachine, comprising: a rotating set with a turbine wheel; a housing containing the rotating set, the housing defining a turbine outlet passage for exhaust from the turbine wheel, the turbine outlet passage pointing in a downstream direction along an axis of the turbine outlet passage; and an air bearing system with at least one bearing component supporting the rotating set for rotation relative to the housing, the air bearing system including a bearing cooling path fluidly connected to the at least one bearing component and having a bearing air conduit outlet fluidly connected to the turbine outlet passage and pointing in the downstream direction along the axis; wherein the bearing air conduit outlet includes a terminal end at the turbine outlet passage, wherein the terminal end points in the downstream direction along the axis.

2. The turbomachinery of claim 1, wherein, the housing includes a turbine casing overlying the turbine wheel, the turbine casing including the turbine outlet passage, the turbine casing including the bearing air conduit outlet.

3. Turbomachine according to claim 2, wherein, the turbine casing at least partially defines a circumferential flow passage arranged upstream of the turbine wheel; and wherein the bearing air conduit outlet is arranged radially outward from the circumferential flow passage relative to the axis.

4. The turbomachinery of claim 3, wherein, the bearing air conduit outlet includes a radially extending segment arranged upstream of the terminal end.

5. The turbomachinery of claim 3, wherein, the turbine casing includes a lip radially separating the bearing air conduit outlet from the turbine outlet passage.

6. The turbomachinery of claim 5, wherein, the turbine casing includes a first turbomachine exhaust conduit and a second turbomachine exhaust conduit arranged in series along the axis and collectively defining the turbine outlet passage; wherein the second turbomachine exhaust conduit is arranged downstream of the first turbomachine exhaust conduit and has a greater width than the first turbomachine exhaust conduit; and wherein the lip is defined at a transition between the first turbomachine exhaust conduit and the second turbomachine exhaust conduit.

7. The turbomachinery of claim 3, wherein, the turbine casing includes an outer turbine casing and an inner turbine casing collectively containing the turbine wheel and collectively defining the circumferential flow passage, the outer turbine casing overlying a front face of the turbine wheel and the inner turbine casing overlying a back face of the turbine wheel; and wherein the outer turbine casing includes the turbine outlet passage and the bearing air conduit outlet.

8. The turbomachinery of claim 7, wherein, the outer turbine casing is unitary.

9. The turbomachinery as recited in claim 7, wherein, the inner turbine casing includes a nozzle structure extending around the turbine wheel, the nozzle structure including at least one nozzle aperture pointing toward the turbine wheel.

10. The turbomachinery of claim 9, wherein, the turbine casing includes a recirculation flow path extending from the circumferential flow passage, through the nozzle structure, and back to the circumferential flow passage.

11. The turbomachine of claim 1, further comprising an electric motor operably connected to the rotating set to drive the rotating set for rotation within the housing.

12. The turbomachinery as recited in claim 1, wherein, the turbine wheel is configured to receive an exhaust stream from a fuel cell stack.

13. A method of manufacturing a turbomachine, comprising: supporting a rotating set of the turbine machine with an air bearing system, the rotating set including a turbine wheel, the housing defining a turbine outlet passage for exhausting gas from the turbine wheel, the turbine outlet passage pointing in a downstream direction along an axis of the turbine outlet passage; and fluidly connecting an air conduit outlet of a bearing cooling path of the air bearing system to the turbine outlet passage, the turbine outlet passage pointing in the downstream direction along the axis; wherein forming a turbine housing includes forming the turbine housing to include a terminal end of the bearing air conduit outlet, the terminal end pointing in the downstream direction along the axis.

14. The method of claim 13, further comprising covering the turbine wheel with a turbine housing of the housing, the turbine housing including the turbine outlet passage, the turbine housing including the bearing air conduit outlet.

15. The method of claim 14, further comprising forming the turbine housing to at least partially define a circumferential flow passage and the bearing air conduit outlet, the air conduit outlet being disposed radially outward from the circumferential flow passage with respect to the axis.

16. The method of claim 15, wherein, forming the turbine housing includes forming a lip that radially separates the bearing air conduit outlet from the turbine outlet passage.

17. The method of claim 13, further comprising providing an electric motor operably connected to the rotating set to drive the rotating set in rotation within the housing.

18. The method of claim 13, further comprising operably attaching the turbine machine to a fuel cell stack, wherein the turbine wheel is configured to receive a flow of exhaust gas from the fuel cell stack.

19. A fuel cell system, comprising: a fuel cell stack; and an electric turbocharger, comprising: a rotating set with a turbine wheel configured to be driven in rotation by high pressure exhaust gas from the fuel cell stack; a housing containing the rotating set, the housing defining a turbine outlet passage for low pressure exhaust gas from the turbine wheel, the turbine outlet passage pointing in a downstream direction along an axis of the turbine outlet passage; and an air bearing system with at least one bearing component supporting the rotating set for rotation relative to the housing, the air bearing system including a bearing cooling path fluidly connected to the at least one bearing component and having a bearing air conduit outlet fluidly connected to the turbine outlet passage and pointing in the downstream direction along the axis; wherein the bearing air conduit outlet includes a terminal end at the turbine outlet passage, wherein the terminal end points in the downstream direction along the axis.

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