Systems and devices for transmitting a fluid flow

Abstract

Turbocharger system (300), which includes: a first turbine (304) having an exhaust outlet (316); a second turbine (308) having an exhaust gas inlet (340); and a transition pipe (310) fluidly connecting the outlet of the first turbine (304) to the inlet (340) of the second turbine (308), the transition pipe (310) having an expansion region (320) upstream of a first manifold (322) and a second manifold (328) downstream of the first manifold (322); characterized in that the first manifold (322) and the second manifold (328) rotate an exhaust gas flow by a total of 180 degrees.

Description

FIELD OF THE INVENTION

[0001] Embodiments of the invention described herein relate to systems and devices for transferring fluid flow between parts of an engine system. Further embodiments relate to fluid flow in a turbocharger system. BACKGROUND

[0002] Turbochargers may be used in conjunction with heat exchangers to provide higher air density and / or pressure to an engine system. In one example, the turbocharger includes a turbine disposed within an exhaust passage of the engine and at least partially driving a compressor to increase intake air pressure. In some embodiments, the engine system may include two or more turbochargers to further increase intake air pressure, such as a two-stage turbocharger including a high-pressure turbocharger fluidly connected to a low-pressure turbocharger. In such an example, exhaust gas may be conveyed from the high-pressure turbine to the low-pressure turbine.In some examples of such an arrangement, the exhaust flow originating from the high-pressure turbine can be rotated by up to 180 degrees, for example, due to available packing space or a desired turbocharger arrangement. Rotating an exhaust flow in this manner can cause flow enthalpy losses, boundary layer separation, pressure losses, and / or non-uniform exhaust flow into the low-pressure turbine.

[0003] WO 2007 / 115659 A2 discloses a turbine housing for a high-pressure turbocharger, comprising a low-pressure charging port for receiving a low-pressure turbocharger and a high-pressure charging port for receiving a high-pressure turbocharger. A high-pressure exhaust port is mounted on an exhaust manifold of an engine, and there is a bypass exhaust port with a high-pressure turbine bypass valve region mounted on the exhaust manifold. An external port is mounted on a muffler, with a wastegate valve region provided in close proximity to the external port.

[0004] US 5,619,854 A discloses a turbocharged diesel engine with a two-stage turbocharger arrangement. The arrangement comprises two parallel-coupled low-pressure turbochargers arranged in series with a single high-pressure turbocharger. The turbochargers can be mounted on a housing that encloses the turbines and exhaust lines and communicates with the exhaust pipe to ensure that exiting exhaust gas escapes to the atmosphere via the exhaust pipe.

[0005] US 7 000 634 B2 discloses a fluid valve comprising a fluid conduit and a flow-reducing device. The flow-reducing device comprises a first fluid passage having a narrow width across an extended flow path defined by internal walls that create a pressure gradient in the fluid flowing through the first fluid passage. The flow-reducing device further comprises a second fluid passage having a narrow width across an extended flow path defined by internal walls. The first fluid passage and the second fluid passage are parallel to each other.

[0006] The invention is based on the object of providing a turbocharger system that reduces the above-mentioned problems and has a higher thermal efficiency. Independent claims 1, 9, and 15 define the invention in various respects. The dependent claims identify embodiments according to the invention. SHORT DESCRIPTION

[0007] In one embodiment, a turbocharger system includes a first turbine having an exhaust outlet and a second turbine having an exhaust inlet. The turbocharger system also includes a transition pipe fluidly connecting the outlet of the first turbine to the inlet of the second turbine, the transition pipe having an expansion region upstream of a first manifold. The system may further include a bypass passage branching an exhaust flow around the first turbocharger, the bypass passage having an exhaust outlet fluidly connected to the transition pipe downstream of the expansion region.

[0008] By using a transition pipe in conjunction with an expansion section, the exhaust flow upstream of a first manifold can be broadened. Furthermore, by introducing exhaust gas that has bypassed the first turbocharger downstream of the expansion section, the exhaust flow flowing through the transition pipe can be restructured after the first manifold. In this way, a pressure drop occurring around the first manifold can be reduced, so that the flow enthalpy is maintained, and a more uniform exhaust flow can be supplied to the second turbine. This increases the efficiency of the turbocharger system and reduces specific fuel consumption, thus increasing the thermal efficiency of the engine.

[0009] It should be understood that the above brief description is presented to introduce, in a simplified form, a selection of concepts that are further described in the detailed description. It is not intended to define important or essential features of the present invention, the scope of which is defined exclusively by the claims appended to the detailed description. Furthermore, the present invention is not limited to implementations that solve disadvantages mentioned above or in other sections of this description. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention will become more understandable after reading the following description of non-limiting embodiments in conjunction with the accompanying drawings: Fig. 1 shows an engine system including a two-stage turbocharger according to an embodiment of the invention. Fig. 2 shows a perspective view of a device for transmitting a fluid flow according to an embodiment of the invention. Fig. 3 shows a cross-sectional view of a transition pipe fluidly connected between two turbochargers according to an embodiment of the invention. DETAILED DESCRIPTION

[0011] The following description relates to various embodiments of systems and devices for an engine with a two-stage turbocharger. In one embodiment, a turbocharger system includes a first turbine having an exhaust outlet and a second turbine having an exhaust inlet. The turbocharger system also includes: a transition pipe fluidly connecting the outlet of the first turbine to the inlet of the second turbine, the transition pipe having an expansion region upstream of a first manifold; and a bypass passage branching an exhaust flow around the first turbocharger. The bypass passage has an exhaust outlet fluidly connected to the transition pipe downstream of the expansion region.In such a construction, the expansion region widens the exhaust flow upstream of the first elbow in the transition tube, and the bypass introduces an exhaust flow downstream of the expansion region, so that energy loss during rotation of the exhaust flow on its path through the first elbow is reduced. Furthermore, in some embodiments, the transition tube further includes an inner body disposed within the transition tube, the inner body configured to maintain an exhaust flow area while an outer diameter of the transition tube increases at a second elbow. By using the inner body in the transition tube, energy losses can be reduced while the exhaust flow changes direction through the second elbow.Thus, the exhaust gas flow can be rotated 180 degrees from the outlet of the first turbine to the inlet of the second turbine while maintaining the flow enthalpy.

[0012] Fig. 1 illustrates one embodiment of an engine system 100. As shown, the engine system 100 includes an engine 104, e.g., an internal combustion engine. The engine 104 may be a diesel engine that combusts air and diesel fuel by compression ignition. In further non-limiting embodiments, the engine 104 may combust fuels such as gasoline, natural gas, hydrogen, kerosene, biodiesel, or other petroleum distillates of similar density by compression ignition (and / or spark ignition). The engine 104 may be included in a propulsion system, e.g., a ship, or a rail vehicle or other off-highway vehicle; in other embodiments, e.g., in a power plant application, the engine 104 may be a stationary engine.

[0013] The engine 104 receives intake air for combustion from an intake duct 114. The intake duct 114 may receive ambient air from an air cleaner (not shown) that filters the air. The exhaust gas produced by combustion in the engine 104 is directed to an outlet, e.g., an exhaust duct 116.

[0014] The engine system 100 also includes a two-stage turbocharger 120 having a first turbocharger (TURBO) 122 and a second turbocharger 124. The first turbocharger 122 and the second turbocharger 124 are connected in series and disposed between the intake passage 114 and the exhaust passage 116. The first turbocharger 122 and the second turbocharger 124 increase the air boost of the ambient air drawn into the intake passage 114 to provide a higher charge density during combustion, thereby increasing power output and / or engine efficiency. In one example, the first turbocharger 122 is a relatively small "high-pressure" turbocharger that operates with air having a relatively high inlet pressure. Furthermore, the second turbocharger 124 in this example is a relatively large “low pressure” turbocharger 124 that operates with air having a relatively low inlet pressure.The pressure ratio produced by the high-pressure turbocharger may be multiplied by the pressure ratio produced by the low-pressure turbocharger to calculate an overall pressure ratio. For example, if only a single turbocharger stage is used, efficiency may decrease as the pressure ratio of one stage increases. However, if a two-stage turbocharger is used, higher pressure ratios may be more effectively achieved using the two lower pressure ratio stages. Additionally, in some examples, a heat exchanger, such as an intercooler, may be disposed between the compressor stages to increase air density and further increase the efficiency of the compression process. As explained in more detail below, and as described in . Fig. 1, a device, for example a transition pipe 130, is arranged between a (in Fig. 1 not shown) outlet of the first turbocharger and one (in Fig. 1) inlet of the second turbocharger 124 to direct exhaust gas flow from the first turbocharger 122 to the second turbocharger 124. While this example utilizes two series-connected turbochargers, the system may include additional turbine and / or compressor stages. Furthermore, in other non-limiting embodiments, the first turbocharger 122 and the second turbocharger 124 may have substantially equivalent compressor pressure ratios.

[0015] As in Fig. 1, the engine system 100 includes a bypass passage 132 that branches an exhaust flow around the first turbocharger 122 to the second turbocharger 124 as desired. The bypass passage 132 includes a wastegate valve 134 or other flow control element. The bypass valve 134 may be a switching valve controlled by a controller 148, or the controller 148 may, for example, regulate / control a variable amount of exhaust flow around the first turbocharger 122. As described in more detail below, an outlet of the bypass passage 132 is fluidly connected to the transition tube 130.

[0016] The controller 148 is a component of the engine system 100 and is configured to control various components associated with the engine system 100. In one example, the controller 148 includes a computer-based control system. The controller 148 also includes computer-readable storage media (not shown) containing code to enable monitoring and control of the operation of the engine system onboard. The controller 148, while overseeing the control and management of the engine system 100, may be capable of receiving signals from various engine sensors 150 to determine operating parameters and operating conditions and adjust various engine actuators 152 accordingly to control the operation of the engine system 100.For example, controller 148 may receive signals from a variety of engine sensors, including, but not limited to, engine speed, engine load, boost pressure, exhaust outlet pressure, ambient pressure, exhaust temperature, and the like. Similarly, controller 148 may control engine system 100 by sending control commands to various components, such as cylinder valves, a throttle, the turbocharger bypass valve 134, and the like.

[0017] Various embodiments of the invention relate to devices for transmitting a fluid flow, e.g., the device can be used as the transition tube 130. In one example, a device for transmitting a fluid flow comprises a first tube section, a second tube section, and a third tube section. The first tube section includes a fluid inlet, and its cross-section increases along a direction of fluid flow (e.g., the fluid flow direction begins at the inlet and extends along the body of the device). The second tube section includes a first bend that turns the fluid flow (e.g., fluid flowing in the direction of the fluid flow) so that it flows at an angle relative to the direction of fluid flow in the first tube section.The third pipe section includes a fluid outlet and a second bend that rotates the fluid flow so that it flows parallel and opposite to the direction of the fluid flow in the first pipe section. The device also has an auxiliary flow inlet. The auxiliary flow inlet is arranged in the first bend of the second pipe section, so that an auxiliary flow entering the second pipe section through the auxiliary flow inlet flows substantially perpendicular to the fluid flow direction of the first pipe section.

[0018] Fig. Figure 2 shows a perspective view of an embodiment of a device 200 for transmitting a fluid flow, e.g. for use as the device shown in Fig. 1. In the examples described herein, the fluid is an exhaust gas from an engine. In other examples, the fluid may be any other suitable gas or liquid.

[0019] As in Fig. 2, the device 200 includes a first pipe section 202, a second pipe section 204, and a third pipe section 206, wherein the second pipe section 204 is arranged downstream of the first pipe section 202, and wherein the third pipe section 206 is arranged downstream of the second pipe section 204. The first, second, and third pipe sections are (directly or indirectly) connected to one another and together define an internal passageway for the exhaust gas flow or for another fluid. For example, the first pipe may define a first portion of the passageway, the second pipe may define a second portion of the passageway (which is fluidly connected to the first portion of the passageway), and the third pipe may define a third portion of the passageway (which is fluidly connected to the second part of the passageway).

[0020] The first tube section 202 includes a fluid inlet 216 through which fluid enters the device 200, and an expansion region 218 whose diameter increases along the fluid flow direction. (The fluid flow direction begins at the fluid inlet 216, extends through the first tube section, then through the second tube section, and then through the third tube section.) As the fluid flows through the first tube section 202, the fluid flow is broadened in the expansion region 218 so that the fluid flow slows down before changing direction (turning), and stall is avoided. The expansion region 218 is described below with reference to Fig. 3 described in more detail.

[0021] The second pipe section 204 includes a first bend 212 and an auxiliary flow inlet 210. The first bend 212 rotates the fluid flow, for example, by an angle in the range of 1 to 179 degrees. (In the Fig. 2, the first manifold 212 rotates the fluid flow by an angle of approximately 90 degrees. As shown, the first manifold 212 is the first manifold downstream of the fluid inlet 216. A pipe 208 through which an auxiliary flow flows is shown connected to the second pipe section 204 of the device 200. In one example, the auxiliary flow may be an exhaust flow that has bypassed a first turbine of a first turbocharger, as previously described with reference to Fig. 1 and below with reference to Fig. 3. As shown, an auxiliary flow inlet 210 is arranged in the first manifold 212 of the device 200 such that the auxiliary flow enters the second pipe section 204 perpendicular to the fluid flow direction of the first pipe section 202. In such a design, the auxiliary flow may, for example, enable restructuring of the flow that has separated while changing direction on its way through the first manifold 212. Furthermore, the auxiliary flow may introduce turbulence into the flow, improving downstream flow conditions.

[0022] The third tube section 206 includes a second bend 220 and a fluid outlet 222. The second bend can rotate the fluid flow through an angle in the range of 1 and 179 degrees. Fig. 2, the second bend 220 rotates the fluid flow through an angle of approximately 90 degrees. Together, the first bend 212 and the second bend 220 can rotate the flow through 180 degrees so that the flow exits the device 200 through the fluid outlet 222 parallel and opposite to the direction of the fluid flow entering the fluid inlet 216. In some embodiments, the third tube section 206 can include an inner body, as described in detail below with reference to Fig. 3. The inner body can be arranged in the third tube section 206 of the device 200 so that a flow cross-sectional area of the device 200 is maintained if a diameter of the device 200 increases while the flow is rotated on its way through the second bend 200. Thus, energy losses due to the rotation of the flow can be reduced by means of the second bend 206.

[0023] As in Fig. As shown in Figure 2, in some embodiments, a bellows 214 is connected between the second tube section 204 and the third tube section 206. The bellows 214 may, for example, compensate for thermal expansion. In other embodiments, the device may not include a bellows, or the device may include more than one bellows, as desired.

[0024] In some embodiments, for example in the Fig. 2, the device further includes a second auxiliary flow inlet 224. In one example, the second auxiliary flow may be an engine cylinder bypass. In such an example, a turbocharger compressor may operate at a more efficient point while maintaining engine demands by utilizing the engine cylinder bypass passage. Furthermore, the engine cylinder bypass passage may be used, if desired, to avoid turbocharger pressure surges during engine speed transitions.

[0025] Thus, the device is capable of transferring a fluid flow such that the fluid flow is rotated by 180 degrees while reducing energy losses due to the rotation of the flow. As described below with reference to Fig. 3, such a device can be fluidly connected, for example, between an outlet of a high-pressure turbocharger and an inlet of a low-pressure turbocharger.

[0026] With reference to Fig. 3, a turbocharger system 300 is shown, for example, the one described above with reference to Fig. 1. The turbocharger system 300 includes a first turbocharger 302 and a second turbocharger 306, which are fluidly connected by a transition pipe 310, e.g., by the method described above with reference to Fig. 2 described device 200 for transmitting a fluid flow. In Fig. 3 shows a top view of the first and second turbochargers 302 and 306, while the transition pipe 310 is shown in a sectional view.

[0027] The first turbocharger 302 includes a first turbine 304, and the second turbocharger 306 includes a second turbine 308. In some embodiments, the first turbine 304 and the second turbine 308 may be largely similar. In other embodiments, the first turbine 304 and the second turbine 308 may be different. For example, the first turbocharger 302 with the first turbine 304 may be a high-pressure turbocharger with a high-pressure turbine, and the second turbocharger 306 with the second turbine 308 may be a low-pressure turbocharger with a low-pressure turbine. The first and second turbochargers 302 and 306 may, for example, be configured to provide desired pressure ratios for a particular engine system. As shown, in one embodiment, a rotational axis 312 of the first turbine 304 is aligned parallel to a rotational axis 314 of the second turbine 308.As used here, the term "rotation axis" refers to an axis around which the turbine's blades rotate. As in . Fig. As shown in Figure 3, the first turbocharger 302 and the second turbocharger 306 are arranged directly adjacent to one another. In such a design, the transition tube 310 between the first turbine 304 and the second turbine 308 can be relatively short, thereby reducing the space required for the turbocharger system.

[0028] Exhaust gas flows from the first turbine 304 to a first tube section 318 through an outlet 316 of the first turbine 304 in a first fluid flow direction. As shown, the outlet 316 of the first turbine 304 is centered about the rotational axis 312 of the first turbine 304. The first tube section 318 has an expansion region 320 whose cross-section increases along the first fluid flow direction from the first turbine 304. For example, a diameter of the transition tube 310 (e.g., a diameter of the inner channel defined by the tube section 318) increases along the fluid flow direction in the expansion region 320, resulting in an increasing cross-sectional area of the transition tube 310 along the fluid flow direction in the expansion region 320. In this way, the exhaust flow may be broadened and decelerated upstream of a bend 322 in the transition tube 310. In some embodiments, for example in the Fig. In the embodiment illustrated in Figure 3, the expansion region has a conical divergence angle 324 of between 10 and 15 degrees. In other examples, the expansion region may have a conical divergence angle of less than 10 degrees or more than 15 degrees, depending on the geometry of the assembly.

[0029] When the exhaust gas flow has widened in the expansion region 320, the exhaust gas flows in a second pipe section 326 of the transition pipe 310 to the first manifold 322. As in Fig. 3, the first elbow 322 is the first elbow in the transition tube 310 downstream of the outlet 316 of the first turbine 304 and the first elbow upstream of the inlet 340 of the second turbine 308. For example, there are no further elbows upstream of the first elbow 322. The first elbow 322 turns the exhaust flow so that it flows at an angle relative to the first direction of the exhaust flow in the first tube section 318. In the Fig. 3, the first manifold 322 rotates the exhaust flow through an angle of approximately 90 degrees. In further embodiments, the first manifold 322 may rotate the exhaust flow through an angle in the range of 1 to 179 degrees, so that in cooperation with a second manifold 328 located downstream of the first manifold 322, it rotates the exhaust flow a total of 180 degrees before entering the second turbine 308. In some embodiments, the first manifold 322 has a radius of curvature 344 of between 165 mm and 200 mm. The radius of curvature 344 may depend on the extent to which the expansion region 320 broadens the exhaust flow upstream of the first manifold 322. For example, the more broadly flowed, the smaller the radius of curvature. Thus, in other examples, the radius of curvature may be greater than 200 mm or less than 165 mm, depending on the flow broadening of the expansion region.

[0030] As the exhaust flow passes through the first manifold 322, it may stall because the flow velocity becomes uneven. Therefore, a bypass passage 330, which branches an exhaust flow around the first turbine 304, is configured such that an outlet 332 of the bypass passage 330 downstream of the expansion region 320 in the first manifold 322 is fluidly connected to the transition tube 310. As shown in Fig. 3, exhaust gas enters the second tube section 326 in the first manifold 322 such that the exhaust flow flows perpendicular to the flow direction in the expansion region 320. The exhaust flow that has bypassed the first turbine 304 may be at a higher temperature and / or pressure than the exhaust flow that has passed through the first turbine 304. In such a construction, the exhaust flow directed from the bypass passage 330 into the transition tube 310 may assist in restructuring the exhaust flow in the transition tube 310 downstream of the first manifold 322, thereby reducing energy losses. Furthermore, the exhaust flow originating from the bypass passage 330 may induce swirl in the exhaust flow flowing through the transition tube 310, which may improve downstream flow conditions.For example, the position of the bypass outlet 332 in the first manifold may vary based on the geometry of the transition tube.

[0031] In some embodiments, the transition includes, as in Fig. 3, also a bellows 334 mounted between the second tube section 326 and a third tube section 336. The bellows 334 can, for example, compensate for thermal expansion in the transition tube 310.

[0032] When the exhaust flow, which contains exhaust gas that has passed through the first turbine 304 and / or the bypass passage 330, flows through the bellows 334, the exhaust flow approaches the second manifold 328 in the transition pipe 310. In the Fig. 3, the second manifold 328 rotates the exhaust flow by an angle of approximately 90 degrees. In further embodiments, the second manifold 328 may rotate the exhaust flow by an angle between 1 and 179 degrees, so that, in cooperation with the first manifold 322, which is located upstream of the second manifold 328, it rotates the exhaust flow by a total of 180 degrees before entering the second turbine 308.

[0033] As in Fig. 3, a cross-section of the second manifold 328 increases along a direction of exhaust flow. For example, a diameter, and thus a cross-sectional area, of the transition tube 310 increases as the exhaust flow passes through the second manifold 328. For example, the diameter of the transition tube 310 may increase such that a cross-section of the outlet of the transition tube matches the cross-section of the inlet of the second turbine. To reduce broadening and stalling of the flow passing through the second manifold 328, in one embodiment, an inner body 338 is disposed within the transition tube 310. The inner body 338 may be a solid body or a hollow body, for example, bolted / screwed to the turbocharger 306 such that the inner body 338 is suspended within the transition tube 310. The inner body 338 may be designed to maintain a flow cross-section of the transition tube.For example, a diameter of the inner body 338 may increase along the direction of exhaust flow in the third tube section 336, so that a cross-sectional area through which the exhaust gas can flow does not increase with increasing diameter of the transition tube 310. In the example of . Fig. 3, the inner body 338 extends into the transition pipe 310 such that a first end 342 of the inner body 338 is disposed in the second manifold 328. In further embodiments, the inner body may be longer or shorter, for example, depending on the geometry of the transition pipe 310. By using an inner body in the third pipe section at a location where a cross-section of the transition pipe increases, stalling of the exhaust flow through the second manifold 328 can be reduced, and the flow enthalpy can be maintained.

[0034] The second manifold 328 rotates the exhaust flow so that it flows parallel, but opposite, to the direction of the exhaust flow in the expansion region 320 of the first tube section 318. Thus, the transition tube 310 rotates the exhaust flow from the outlet 316 of the first turbine 304 to an inlet 340 of the second turbine 308 by approximately 180 degrees. As shown in Fig. 3, the inlet 340 of the second turbine 308 is centered around the rotation axis 314 of the second turbine 308, which is parallel to the rotation axis 312 of the first turbine 304.

[0035] In the Fig.3, no intermediate devices (e.g., intercoolers or the like) are arranged between the outlet 316 of the first turbine 304 and the inlet 340 of the second turbine 308. Furthermore, the transition pipe 310 defines a rotation of 180 degrees. For example, the first flow direction merely transitions by 90 degrees into a second flow direction, which merely transitions by 90 degrees into a third direction. This means that there are no further rotations in the transition pipe 310 apart from the first manifold 322 and the second manifold 328. In this way, an exhaust gas flow can be efficiently transferred from the first turbine 304 to the second turbine 308 in a relatively small space.

[0036] Thus, as described above, the transition pipe fluidically connects the outlet of the first turbine with the inlet of the second turbine. The transition pipe turns the exhaust gas flow originating from the first turbine by 180 degrees on its way through a first bend and through a second bend before it reaches the second turbine. By broadening the exhaust gas flow across the expansion region and by introducing the exhaust gas flow that has bypassed the first turbine downstream of the expansion region, energy losses on the way through the first bend in the transition pipe can be reduced. Furthermore, energy losses in the exhaust gas flow on the way through the second bend in the transition pipe can be reduced by using the inner body in the transition pipe.Thus, the flow enthalpy in the transition pipe can be maintained, reducing the pressure drop in the transition pipe and transferring an exhaust flow with a uniform velocity profile to the second turbine. Accordingly, the efficiency of the second turbocharger can be increased, reducing specific fuel consumption and increasing the thermal efficiency of the engine.

[0037] Another embodiment relates to a device for transmitting a fluid flow. The device includes a first pipe section having a fluid inlet, a second pipe section, and a third pipe section having a fluid outlet. The first, second, and third pipe sections are (directly or indirectly) attached to one another and together define a fluid flow channel and a fluid flow direction extending from the fluid inlet, through the first pipe section, then through the second pipe section, and then through the third pipe section to the fluid outlet. (For example, a fluid forced through the fluid inlet in the direction of fluid flow typically moves through the fluid flow channel, along the first pipe section, then along the second pipe section, then along the third pipe section, to exit the device through the fluid outlet.)In the first pipe section, the cross-section of the fluid flow channel increases along at least part of the length of the first pipe section in the direction of fluid flow. (For example, if the first pipe section has a length, the flow channel has a maximum dimension "A" at a first point, and the flow channel has a maximum dimension "B" at a second point, where B is greater than A (B > A), and where the second point is farther away in the direction of fluid flow over the length than the first point.) The second pipe section includes a first bend that rotates the fluid flow direction in the second pipe section by an angle with respect to the direction of fluid flow in the first pipe section. The third pipe section includes a second bend that rotates the fluid flow direction in the third pipe section parallel and opposite to the direction of the fluid flow flowing in the first pipe section, e.g.a fluid moving through the first pipe section in a first direction, then through the second pipe section, and then through the third pipe section is rotated by the third pipe section in a direction substantially parallel and opposite to the first direction. The second pipe section has an auxiliary flow inlet. The auxiliary flow inlet is arranged in the first bend and is configured to discharge an auxiliary flow flowing perpendicular to the fluid flow direction of the first pipe section. For example, an auxiliary flow entering the second pipe section through the auxiliary flow inlet typically flows perpendicular to the fluid flow direction of the first pipe section.

[0038] In another embodiment of the device for transmitting a fluid flow, the device includes a first pipe section having a fluid inlet, a second pipe section connected to the first pipe section, and a third pipe section having a fluid outlet and connected to the second pipe section. Along a fluid flow direction extending from the fluid inlet, through the first pipe section, then through the second pipe section, and then through the third pipe section to the fluid outlet, the cross-section of the first pipe section increases at least along part of its length. The second pipe section includes a first bend that rotates the fluid flow direction of the second pipe section by an angle with respect to the direction of fluid flow of the first pipe section.The third pipe section includes a second bend that rotates the fluid flow direction of the third pipe section parallel and opposite to the fluid flow direction of the first pipe section. The device also has an auxiliary flow inlet arranged in the first bend, so that an auxiliary flow entering the second pipe section through the auxiliary flow inlet flows (at least initially) perpendicular to the fluid flow direction of the first pipe section.

[0039] In another embodiment of the device for transmitting a fluid flow, the device includes a first pipe section having a fluid inlet and defining a first fluid flow channel. Along at least a portion of the length of the first fluid flow channel, the cross-section of the first fluid flow channel increases in the direction of a fluid flow extending from the fluid inlet and along the first fluid flow channel. The device further includes a second pipe section defining a second fluid flow channel fluidly connected to the first fluid flow channel. The second pipe section includes a first bend such that a fluid flowing from the first pipe section through the second pipe section to the third pipe section forms an angle with respect to the fluid flow direction of the first fluid flow channel.The second tube section has an auxiliary flow inlet arranged in the first bend and configured such that an auxiliary flow entering the second fluid flow channel through the auxiliary flow inlet flows (at least initially) perpendicular to the fluid flow direction of the first fluid flow channel. The device further includes a third tube section defining a third fluid flow channel fluidly connected to the second fluid flow channel and having a fluid outlet. The third tube section includes a second bend such that a fluid flowing from the second tube section through the third tube section to the fluid outlet is rotated parallel and opposite to the fluid flow direction of the first tube section.

[0040] Another embodiment relates to a turbocharger system for an engine. The turbocharger system includes a first turbocharger and a second turbocharger. The first turbocharger is a high-pressure turbocharger, and the second turbocharger is a low-pressure turbocharger. The first turbocharger has a first, high-pressure turbine, and the second turbocharger has a second, low-pressure turbine. The first turbine is fluidly connected to an engine exhaust outlet; the first turbine is located downstream of the exhaust outlet. The second turbine is arranged downstream of the first turbine; thus, the first turbine is located upstream of the second turbine, and the engine exhaust outlet is located upstream of the first and second turbines.An outlet of the first turbine is fluidly connected to an inlet of the second turbine such that exhaust gas flowing from the engine exhaust outlet and through the first turbine is branched to the second turbine. For fluid flow communication, the turbocharger system includes a device for transferring fluid (e.g., exhaust gas) between the first and second turbines. The device includes a first tube section having a first body (e.g., a metallic body) defining a first passageway and a fluid inlet into the first passageway. The fluid inlet is connected to the outlet of the first turbine such that the first passageway and the outlet of the first turbine are fluidly connected via the fluid inlet. Thus, exhaust gas leaving the outlet of the first turbine flows through the fluid inlet of the first tube section and into and through the first passageway.The first passageway has an expansion region, the first passageway expanding outwardly as it extends from the fluid inlet and along the direction in which exhaust gas typically flows when traveling from the first turbine to the second turbine. Thus, the first passageway has a first lateral region (perpendicular to the axis of flow direction in the first passageway) at the beginning of the expansion region and a second, larger lateral region at the end of the expansion region. For example, the expansion region may comprise the portion of the body of the first tube section that defines the expansion region of the conically shaped flow channel.

[0041] The device further includes a second pipe section connected to the first pipe section. (The connection can be direct or indirect, the latter meaning that the two parts are connected by an intermediate piece.) The second pipe section has a second pipe body (e.g., a metallic body) defining a second passageway; the second passageway is fluidly connected to the first passageway of the first pipe body downstream of the expansion region. The second pipe section includes a first bend in the second passageway such that a portion of the length of a centerline of the second passageway is arranged at an angle (of 1 - 179 degrees, e.g., 90 degrees) relative to a centerline (and direction of outlet flow) of the first passageway of the first pipe section.When, in operation, exhaust gas flows from the first turbine through the first pipe section in a first direction and then through the second pipe section, the second pipe section therefore rotates the exhaust gas flow by an angle (e.g., 90 degrees) relative to the first direction.

[0042] The device further includes a third pipe section which is directly or indirectly connected to the second pipe section downstream of the first manifold. The third pipe section has a third pipe body (e.g., a metallic body) defining a third passageway and a fluid outlet; the third passageway is fluidly connected to the second passageway and thereby to the first passageway. The third pipe section is connected to an inlet of the second turbine of the second turbocharger in alignment with the fluid outlet of the third pipe section; in this way, a fluid flow path runs from the third passageway, through the fluid outlet, through the fluid inlet of the second turbine, and into the second turbine.The third pipe section includes a second bend in the third passage such that a portion of the length of a centerline of the third passage is arranged at an angle (1 - 179 degrees, e.g., 90 degrees) relative to the centerline of the second passage. Therefore, when exhaust gas flows through the second pipe section and subsequently through the third pipe section during operation, the exhaust gas is rotated by an angle in the third passage relative to the direction in which it flows through the second passage.

[0043] In one embodiment, a rotational axis of the first turbine is parallel to a rotational axis of the second turbine, and the outlet of the first turbine faces in the same direction as the inlet of the second turbine. During operation, the first and second manifolds cause the exhaust flow exiting the first turbine to rotate 180 degrees and in an opposite direction to enter the second turbine.

[0044] In another embodiment, the fluid transfer device further includes an auxiliary flow inlet attached to the second tube section and disposed in the first manifold. The auxiliary flow inlet defines a fluid flow path between the second passageway and an exterior of the second tube section. The auxiliary flow inlet may be connected to a bypass flow path of the first turbine. During operation, an auxiliary flow flowing through the bypass flow path enters the second passageway through the auxiliary flow inlet. The auxiliary flow inlet is configured (e.g., sized and oriented) such that the auxiliary flow flowing through the auxiliary flow inlet into the second passageway flows perpendicular to the direction of fluid (e.g., exhaust gas) flowing through the first tube section.

[0045] Thus, in one embodiment, during operation, exhaust gas leaves the first turbine and flows through the first tube section in a first direction. The exhaust gas expands in the expansion region of the first tube section. The exhaust gas enters the second tube section and is rotated, e.g., by 90 degrees. Meanwhile, an auxiliary flow (e.g., of exhaust gas that has bypassed the first turbine) flows through the auxiliary flow inlet into the second tube in a second direction, which may be perpendicular to the first direction. The auxiliary flow mixes with the exhaust gas from the first turbine. The combined flow enters the third tube section where it is rotated, e.g., by 90 degrees (in a direction parallel and opposite to the first direction), and flows through the fluid outlet of the third tube section and into the inlet of the second turbine of the second turbocharger.

[0046] In one embodiment, the diameter of the third passageway of the third tube section increases as the third tube transitions from the second tube section to the inlet of the second turbine. In another embodiment, the system further includes an inner body disposed in the third passageway. The flow is branched around the inner body, and the inner body is dimensioned such that a flow cross-sectional area of the third passageway remains constant over the length of the second passageway, whereas the diameter increases.

[0047] As used here, a value that lies "between" two numerical endpoints includes both endpoints and the range between the endpoints.

[0048] As used herein, elements or steps mentioned in the singular and preceded by the indefinite article should be understood in the sense that the plural of the elements or steps is not excluded, unless such exclusion is expressly stated. Furthermore, reference to "one embodiment" of the present invention should not be interpreted as excluding the existence of additional embodiments that also embody the recited features. Moreover, embodiments that "include," "contain," or "have" one or more elements with a particular property may include other such elements, unless expressly stated otherwise. The terms "including" and "in which" are used as common-sense equivalents of the corresponding terms "have" and "wherein."Furthermore, the terms “first,” “second,” “third,” and the like are for identification purposes only and are not intended to impose any numerical requirements or a specific order of arrangement on their objects.

[0049] This description uses examples to describe the invention, including the best mode, and to enable one skilled in the art to practice the invention, for example, to make and use any devices and systems, and to perform any related methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to one skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal content of the claims.

Claims

[1] Turbocharger system (300), which includes: a first turbine (304) having an exhaust outlet (316); a second turbine (308) having an exhaust gas inlet (340); and a transition pipe (310) fluidly connecting the outlet of the first turbine (304) to the inlet (340) of the second turbine (308), the transition pipe (310) having an expansion region (320) upstream of a first manifold (322) and a second manifold (328) downstream of the first manifold (322); characterized by that the first manifold (322) and the second manifold (328) rotate an exhaust gas flow by a total of 180 degrees. [2] The turbocharger system of claim 1, further comprising a bypass passage (330) directing an exhaust flow around the first turbine (304), the bypass passage (330) having an exhaust outlet (332) fluidly connected to the transition tube (310) downstream of the expansion region (320). [3] The turbocharger system of claim 2, wherein the exhaust outlet (332) of the bypass passage (330) directs an exhaust flow into the transition tube (310) perpendicular to a direction of the exhaust flow exiting the exhaust outlet (316) of the first turbine (304). [4] Turbocharger system according to claim 1, wherein a rotational axis (312) of the first turbine (304) is aligned parallel to a rotational axis (314) of the second turbine (308). [5] The turbocharger system of claim 1, wherein the turbocharger system is a two-stage turbocharger system, and wherein the first turbine (304) is a high-pressure turbine and the second turbine (308) is a low-pressure turbine. [6] Turbocharger system according to claim 1, wherein a rotational axis (312) of the first turbine (304) is aligned parallel to a rotational axis (314) of the second turbine (308), wherein the turbocharger system is a two-stage turbocharger system, wherein the expansion region (322) has a divergence angle in the range of 10 and 15 degrees, and wherein the first manifold (322) has a radius of curvature in the range of 165 mm and 200 mm. [7] The turbocharger system of claim 1, wherein the transition tube (310) includes a bellows (334) disposed downstream of the first manifold (322) and upstream of the second manifold (328). [8] The turbocharger system of claim 1, wherein the transition tube (310) further includes an inner body (338) disposed within the transition tube (310), the inner body (338) configured to maintain a flow area of the transition tube (310) as a diameter of the transition tube (310) increases at the second manifold (328). [9] Device for transferring a fluid flow, comprising: a first tube section (318) having a fluid inlet and defining a first fluid flow channel, the cross-section of the first fluid flow channel increasing along at least a portion of a length of the first fluid flow channel in the direction of fluid flow extending from the fluid inlet (340) and along the first fluid flow channel; a second tube section (326) defining a second fluid flow channel fluidly connected to the first fluid flow channel, wherein the second tube section (326) includes a first bend (322) such that a fluid flowing from the first tube section (318) through the second tube section (326) has an angle relative to the fluid flow direction of the first fluid flow channel, and wherein the second tube section (326) includes an auxiliary flow inlet disposed in the first bend (322) and configured such that an auxiliary flow entering the second fluid flow channel through the auxiliary flow inlet flows at least initially perpendicular to the fluid flow direction of the first fluid flow channel; and a third tube section (336) defining a third fluid flow channel fluidly connected to the second fluid flow channel and having a fluid outlet, the third tube section (336) including a second elbow (328) such that fluid flowing through the third tube section (336) from the second tube section (326) to the fluid outlet is rotated parallel and opposite to the direction of fluid flow of the first tube section (318). [10] The device of claim 9, wherein the increasing cross-section of the first tube section (318) corresponds to a conical divergence angle between 10 and 15 degrees. [11] The apparatus of claim 9, further comprising a bellows mounted between the second tube portion (326) and the third tube portion (336). [12] The apparatus of claim 9, wherein the second pipe section (326) is disposed downstream of the first pipe section (318), and wherein the third pipe section (336) is disposed downstream of the second pipe section (326). [13] The apparatus of claim 9, further comprising an inner body (338) disposed within the third tube portion (336) and configured to maintain a flow cross-section of the third tube portion (336) as a diameter of the third tube portion (336) increases. [14] The apparatus of claim 9, wherein the fluid inlet (340) is fluidly connected to an outlet (316) of a first turbine (304) of a first turbocharger (302), and wherein the fluid outlet is fluidly connected to an inlet (340) of a second turbine (308) of a second turbocharger (306). [15] An engine system (300) comprising: a high-pressure turbine (304) of a high-pressure turbocharger disposed in an exhaust passage of an engine; a low-pressure turbine (308) of a low-pressure turbocharger, wherein a rotational axis (314) of the low-pressure turbine (308) is aligned parallel to a rotational axis (312) of the high-pressure turbine (304), and wherein the low-pressure turbine (308) is arranged downstream of the high-pressure turbine (304) in the exhaust gas duct; and a transition pipe (310) fluidly connecting an outlet (316) of the high-pressure turbine (304) to an inlet (340) of the low-pressure turbine (308), the transition pipe (310) comprising: an expansion region (320) located upstream of a first manifold (322); a high-pressure turbine bypass duct (330) having a bypass outlet disposed downstream of the expansion region (320); and an inner body (338) disposed within the transition tube (310), the inner body (338) being configured to maintain a flow cross-section downstream around a second bend (328) as an outer diameter of the transition tube (310) increases. [16] The engine system of claim 15, wherein a cross-section of the expansion region (320) increases along a fluid flow direction. [17] The engine system of claim 15, wherein the bypass outlet of the high pressure turbine bypass duct (330) is disposed in the first manifold (322) to direct the exhaust flow into the transition tube (310) perpendicular to a direction of the exhaust flow exiting the outlet of the high pressure turbine (304). [18] The engine system of claim 15, wherein the transition tube rotates an exhaust flow from the engine by 180 degrees on the way from the outlet (316) of the high pressure turbine (304) to the inlet (340) of the low pressure turbine (308). [19] The engine system of claim 15, wherein the second manifold (328) is disposed downstream of the first manifold (322).

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