WO2009046292A2

WO2009046292A2 - System and method for air flow control in a turbocharger

Info

Publication number: WO2009046292A2
Application number: PCT/US2008/078739
Authority: WO
Inventors: David Andrews
Original assignee: BorgWarner Inc
Current assignee: BorgWarner Inc
Priority date: 2007-10-04
Filing date: 2008-10-03
Publication date: 2009-04-09
Anticipated expiration: 2010-04-04
Also published as: WO2009046292A3

Abstract

A system and method for air flow control in a turbocharger is provided The system can have a control device for providing a compressed fluid to an engine (12, 112) The device can have a housing (33), a compressor (28, 170) in fluid communication with a source of fluid and the engine (12, 112) where the compressor (28, 170) has an inlet (58) and an outlet and where the compressor (28, 170) is positioned in the housing (33). The device can also have a flow controller (52) in fluid communication with the inlet (58) and outlet of the compressor (28, 170), where the flow controller (52) selectively provides the compressed fluid from the outlet of the compressor (28, 170) to the inlet (58) of the compressor (28, 170) and provides the fluid to the engine (12, 112) by bypassing the compressor (28, 170).

Description

SYSTEM AND METHOD FOR AIR FLOW CONTROL IN A TURBOCHARGER

FIELD OF THE INVENTION

[0001] This invention is directed to a turbocharging system for an internal combustion engine and more particularly to a system and method for controlling air flow.

BACKGROUND OF THE INVENTION

[0002] Air systems, such as turbochargers, are a type of forced induction system. They compress the air flowing into an engine, thus boosting the engine's horsepower without significantly increasing weight. Air systems are used in vehicles in order to increase the efficiency of an engine and reduce the emissions of the vehicle by recirculating exhaust gas and compressing the intake air.

[0003] Air systems use a turbocharger where the exhaust gas passes through a turbine which is connected to a compressor. Thus, the compressor compresses intake air which is directed towards the intake manifold of the engine. However, the pressure ratio between the output of the compressor and the input of the compressor can be at such a high ratio that the air system is working under unstable operating conditions. These unstable operating conditions can lead to low compressor efficiency, material failure, or high emissions among other things.

[0004] Therefore, it would be desirable to develop an air system in which the pressure ratio of the output side of the compressor and the input side of the compressor can be controlled in order to avoid operation under high pressure ratio conditions. It would also be desirable to design the recirculation-bypass system to reduce the pressure ratio in a compact assembly in order to reduce the amount of weight and space occupied by the additional components of the air system. SUMMARY OF THE INVENTION

[0005] In one embodiment according to inventive aspects of the present disclosure, a control device for providing a compressed fluid to an engine is provided. The device can have a housing, a compressor in fluid communication with a source of fluid and the engine where the compressor has an inlet and an outlet and where the compressor is positioned in the housing. The device can also have a flow controller in fluid communication with the inlet and outlet of the compressor, where the flow controller selectively provides the compressed fluid from the outlet of the compressor to the inlet of the compressor and provides the fluid to the engine by bypassing the compressor.

[0006] In another embodiment, a multi-stage turbocharger system is provided. The system can have an engine having an intake manifold and an exhaust manifold, a first turbine positioned downstream of said exhaust manifold where the first turbine has an inlet for receiving exhaust gas from the exhaust manifold and an outlet for providing the exhaust gas downstream, a second turbine downstream of said first turbine and having an inlet and an outlet where the iniet of the second turbine receives the exhaust gas from the first turbine, a compressor having an inlet and an outlet where the inlet of the compressor is in fluid communication with a source of fluid and is driven by one of the first or second turbines, and a flow control device upstream of said intake manifold and having a flow controller with an inlet and outlet where the outlet of the flow controller is in fluid communication with the intake manifold. The inlet of the flow controller can be in fluid communication with both the inlet and outlet of the compressor, where the flow controller can selectively bypass the fluid around the compressor and recirculate compressed fluid from the outlet of the compressor to the inlet of the compressor.

[0007] In another embodiment, a method of managing flow of a fluid to an engine is provided. The method can include providing a source of fluid; compressing the fluid using a compressor wheel of a compressor; and selectively recirculating the compressed fluid to an inlet of the compressor and bypassing the fluid to the engine around the compressor using a single flow control device. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present invention is illustrated by way of example and not limitation in the accompanying drawings in which like reference numbers indicate similar parts, and in which:

[0009] Fig. 1 is a schematic diagram of a two stage turbocharged engine having an exemplary embodiment of an air control device of the present disclosure in a bypassing mode;

[0010] Fig. 2 is a schematic diagram of the two stage turbocharged engine of FIG. 1 with the air control device in a recirculation mode;

[0011] Fig. 3 is a schematic diagram of the two stage turbocharged engine of FIG. 1 with the air control device in a two-stage mode;

[0012] Fig. 4 is a schematic diagram of a two stage turbocharged engine having another exemplary embodiment of the air control device of the present disclosure;

[0013] Fig. 5 is a schematic diagram of a one stage turbocharged engine having another exemplary embodiment of the air control device of the present disclosure;

[0014] Fig. 6 is a schematic diagram of a two stage turbocharged diesel engine having another exemplary embodiment of the air control device of the present disclosure;

[0015] Fig. 7 is a side view of a compressor, schematically illustrating the integrated throttle valve of the air control device of FIGS. 5 or 6 in a partly closed position with the recirculation bypass channel in an open position; and [0016] Fig, 8 is a side view, schematically illustrating a compressor showing an integrated throttle valve of the air control device of FIGS. 5 or 6 in its open position, while the recirculation-bypass channel is also in its open position.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Referring to Figs. 1 to 3, a two stage turbocharged engine 12 is illustrated having an exemplary embodiment of a fluid control system 10 in accordance with inventive aspects of the present disclosure. The engine 12 can have various components such as an exhaust gas manifold and an intake manifold. Flow paths with respect to components of the system 10 and the engine 12 are shown by arrows, where solid arrows represent flow paths of lesser resistance as compared to broken arrows. The flow paths of lesser resistance can have all or some of the fluid flow, while the flow paths of greater resistance can have none or some of the fluid flow. A fluid path from the engine 12 can lead to a first or high pressure turbine 120 and to a turbine bypass valve 162. The turbine bypass valve 162 can control the flow of fluid to the turbine 120 by bypassing all, some or none of the fluid. The bypass valve 162 and/or bypass conduit can be integrally formed with or contained in a housing (not shown) of the turbine 120. However, the present disclosure also contemplates one or both of the bypass valve 162 and bypass conduit being separate components outside of the housing. Fluid leaving the outlet of the first turbine 120 and/or the bypass valve 162 can be provided to a second or low pressure turbine 164. In one embodiment, a second turbine bypass valve and/or channel can divert some or all of the fluid around the second turbine 164, such as to an exhaust pipe or to a recirculation channel.

[0018] The system 10 can have a low pressure compressor 170 and a high pressure compressor 28. A fluid control device or valve 52 can be placed in fluid communication with the low pressure compressor 170, the high pressure compressor 28 and an air cooler 136. The control device 52 and/or control conduit can be integrally formed with or contained in the housing (not shown) of the compressor 28. However, the present disclosure also contemplates one or both of the control device 52 and the control conduit being separate components outside of the housing.

[0019] In operation, the control device 52 can selectively perform the functions of recirculation and blow-off with respect to the compressor 28. For example as depicted in Fig. 1 , system 10 can be placed into a bypass mode where the high pressure compressor 28 is completely or partially bypassed by the control device 52. The bypass mode can be implemented for instance during high engine power operation, although the present disclosure contemplates the bypass mode being implemented under other operating conditions. The amount of fluid that bypasses the high pressure compressor 28 as a result of operation of the control device 52 can vary. In one embodiment, the amount of fluid bypass can be selectively adjusted based on operating conditions and/or other factors.

[0020] As depicted in Fig. 2, system 10 can be placed into a recirculation mode where compressed fluid from the high pressure compressor 28 is recirculated back to the high pressure compressor by the control device 52. The amount of recirculation can be complete or partial. The recirculation mode can be implemented for instance during an engine transient condition where the engine 12 goes from a boosted state to an idle state to avoid surging by the compressor 28, although the present disclosure contemplates the recirculation mode being implemented under other operating conditions. The amount of fluid that is recirculated to the high pressure compressor 28 as a result of operation of the control device 52 can vary. In one embodiment, the amount of fluid recirculation can be selectively adjusted based on operating conditions and/or other factors.

[0021] As depicted in Fig. 3, system 10 can be placed into a two-stage mode where the fluid control device 52 can provide all of the fluid from the low pressure compressor 170 to the high pressure compressor 28, and then provide the fluid to the engine 12 and cooler 48. The two-stage mode can be implemented for instance during certain engine operating ranges. In one embodiment, the two- stage mode can be implemented by placing the fluid control device in a closed or unactuated state.

[0022] The present disclosure also contemplates the use of flow control device 52 in a single stage turbocharger or any number of stages, including the use of more than one flow control device in the system 10. In one embodiment, a flow control device 52 can be coupled to each of the compressors in a multi-stage turbocharger or to any number of the compressors, such as coupled to the high and medium pressure compressors but not the low pressure compressor in a three stage compressor. The present disclosure contemplates various configurations for the use of one or more flow control devices 52 with any number of stages of a turbocharger.

[0023] Referring to Fig. 4, a two stage turbocharged diesel engine is illustrated depicting another embodiment 110 of the present invention. The system 110 can include an engine 112 and exhaust gas manifold 116, along with an intake manifold 1 14. A high pressure EGR path 146 can deliver exhaust gas from exhaust manifold 1 16 to an intake path 140 that leads to the intake manifold 114 of the engine. The exhaust gas that enters the EGR path 146 can first pass through an EGR cooler 148 in order to reduce the temperature of the exhaust gas, and then can pass through an EGR valve 150.

[0024] A path 18 from the exhaust manifold 1 16 can lead to a high pressure turbine 120 and to a first or turbine bypass channel 160 with a bypass valve 162 for controlling the flow of fluid through the bypass channel 160. The bypass channel 160 can be formed in part of the housing of the turbine 120, although the present disclosure also contemplates the channel being a separate component. The bypass valve 162 and the bypass channel 160 can operate to selectively divert the flow of some or all of the fluid around the turbine 120. Fluid leaving the outlet of the first turbine 120 or bypass channel 160 can then be provided to a second turbine 164 and to a second turbine bypass channel 166 with a bypass valve 168 that can divert some or all of the fluid around the second turbine 164. The second bypass channel 160 and bypass valve 168 can be formed in a housing that contains the second turbine 164, although the present disclosure also contemplates the channel being a separate component. In one embodiment, the turbines 120, 164, the bypass channels 160, 166 and the bypass valves 162, 168 can be positioned in a single housing, such as a cast housing.

[0025] After the fluid passes through the outlet of the second turbine 164 and/or the second bypass channel 160, the fluid can be provided to a filter 122, such as to clean soot or other materials from the fluid. The fluid can then be provided to an exhaust throttle and EGR valve system 124. The fluid or exhaust gas can exit the system 110 by being delivered to the exhaust pipe 126 and/or can be provided to an EGR path 142 which includes an EGR cooler 144. The amount of the fluid exiting the system and the amount being provided to the EGR path can vary depending on a number of factors, including engine operating conditions and engine speed. The fluid that is to be recompressed can then be mixed with fresh air, such as from inlet 128.

[0026] Upstream from the inlet pipe 128, a low pressure compressor 170 and a high pressure compressor 28 can be provided. An air device 33 can include a recirculation-bypass channel 44 with the fluid control device 52. The fluid control device 52 can be a valve or other structure that is operable to place system 1 10 in: the bypass mode (i.e., to bypass some or all of the fluid around the compressor 28 such as a rotatable wheel); the recirculation mode (i.e., to recirculate compressed fluid back to the high pressure compressor wheel 28); and the two- stage mode (i.e., provide all of the fluid from the compressor 170 through the compressor 28 to the engine 112. Monitoring of pressure Pi (at the inlet 58) and P₂ , such as by a pressure transducer or other sensor, can be used to determine which of the modes (bypass, recirculation, two-stage) the system 110 should utilize. A charge air cooler 136 can cool the compressed fluid prior to entry to an inlet 140 of the intake manifold 1 14.

[0027] Referring to Fig. 5, a schematic diagram of the exhaust gas recirculation- bypass system 10 using an air device used in conjunction with a single stage turbocharger is generally shown. The air system 10 can include an engine 12 which has an exhaust manifold 14. Connected to the exhaust manifold 14 can be a turbine 16 with variable vanes and an exhaust gas recirculation-bypass (EGR) path 18, such that the exhaust gas from the exhaust manifold 14 can enter either the turbine 16 or the EGR path 18. The exhaust gas that enters the EGR path 18 can first pass through an EGR cooler 20 in order to reduce the temperature of the exhaust gas, and then can pass through an EGR valve 22. The EGR valve 22 can be a high pressure EGR valve. The exhaust gas can be mixed with an exhaust gas and fresh air combination, and can enter the intake manifold 24.

[0028] The exhaust gas that does not pass through the EGR path 18 can pass through a turbine 16, which is operably connected to a compressor 28. The turbocharger 30 can contain the turbine 16 and the compressor 28, and the exhaust gas can rotate the turbine 16 which then rotates the compressor 28. After the exhaust gas passes through the turbine 16, the exhaust gas can pass through a diesel particulate filter 32 (DPF) which removes soot from the exhaust gas. After the exhaust gas passes through the DPF 32, a portion of the exhaust gas can exit the air system 10 through the exhaust pipe 34, and a portion of the exhaust gas can pass through a low pressure EGR throttle valve 36 and into an EGR path 38. The EGR throttle valve 36 can have an EGR valve portion and a throttle valve portion that are part of a single unit, or they may be separate units.

[0029] The amount of gas that passes through each of the EGR path 38 and the exhaust pipe 34 is controlled by the EGR throttle valve 36, such that when the EGR throttle valve 36 is open more gas can pass through the EGR path 38 and when the EGR throttle valve 36 is closed more gas can exit the air system 10 through the exhaust pipe 34. The EGR valve and throttle valve can work in combination so that the EGR valve portion can be opened and the throttle valve portion can be closed to allow maximum flow through the EGR path 38. The EGR valve portion can also be closed and the throttle valve portion can be opened to allow maximum flow through the exhaust pipe 34. The exhaust gas that does pass through the EGR path 38 can then pass through an EGR cooler 42 in order to reduce the temperature of the exhaust gas. After passing through the EGR cooler 42, the exhaust gas can be mixed with fresh air and move to an air device 33 that contains the compressor 28, where the pressure of the exhaust gas and fresh air is increased. Under certain operating conditions, the pressure of the air on the input side of the compressor 28 can be lower than the pressure of the air on the output side of the compressor 28.

[0030] Referring now to Figs. 5, 7 and 8, the system 10 can have an air device 33 that combines a throttle valve aspect 26, a rotatable wheel or compressor 28, a recirculation-bypass channel 44 and a recirculation-bypass valve aspect 46 into a single housing 29. Within the single housing 29 there can be a variable air intake mechanism in the form of device or valve 52 that provides the throttle valve aspect 26, and the recirculation-bypass valve aspect 46. The scope of this invention is not limited to providing both aspects in one application but can include one or both of these aspects. The air device 33 can control the flow and pressure of fluid that flows into a charge air cooler 48 and the intake manifold 24. The air device 33 can also work with the EGR path 18 to increase the uptake of high pressure EGR from the EGR path 18 to the intake manifold 24. The housing 29 can have an inlet 58 constituting a low pressure area for receiving fluid medium such as outside air from an air intake, recirculated exhaust gas from the EGR path 38 or a mixture of outside air and exhaust gas. The housing 29 can also have an outlet 60 constituting a high pressure area that is connected to a path that leads to the intake manifold 24. The compressor 28 can be circumscribed by the air device valve 52. The air device valve 52 can be a butterfly plate, drum, sliding collar or other type of valve.

[0031] Figs. 7 and 8 depict the device or valve 52 as a sliding collar connected to an actuator 62 or actuators. The actuator 62 can be any type of controlling mechanism, for example it can be a solenoid, pneumatic, hydraulic actuator or other type of system. The actuator 62 can act on the device 52 to slide between a closed position, an opened position and/or any position there between.

[0032] Using increased high pressure EGR flow through the EGR path 18 can be achieved through throttling while keeping the high pressure valve 22 fully open. The throttle valve aspect 26 of the present disclosure can provide this desired result. As illustrated in Fig. 7, when the device 52 is closed past a certain position throttling of the fluid medium past the device 52 can occur. The throttling movement of the air past the device 52 can vary depending on several factors such as the shape of the device 52 and/or the degree of opening between the device and the housing 29. This throttling action can lower the pressure downstream of the air device 33. This can cause increased flow from the EGR path 18. When the EGR valve 22 is open and the throttle valve aspect 26 is closed the maximum flow through the EGR path 18 can be created. When the EGR valve 22 is closed and the throttle valve aspect 26 is opened, the maximum amount of flow from the compressor 28 can enter the intake manifold 24.

[0033] Fig. 8 illustrates the bypass aspect of the recirculation-bypass channel 44. When the device or valve 52 is in a more opened position and the pressure at the inlet 58 of the air device 33 is greater than what the compressor 28 can move then the fluid moving through the air device 33 can bypass the compressor wheel 28 through the recirculation-bypass channel 44 and exit through the outlet 60. This type of situation can more likely occur in a system where there is another compressor or turbine passage located upstream of the air device 33 that would increase the pressure to the point where bypass would be beneficial, although the present disclosure contemplates implementing this control with various configurations of turbochargers. The flow of fluid through the recirculation 30 bypass passage 44 can be controlled by a regulation mechanism 53 that is operably connected to the device 52. The regulation mechanism 53 can be a flange that slides in the recirculation-bypass passage 44 or it can be some type of valve member or mechanical device suitable for regulating flow.

[0034] The regulation mechanism 53 can be designed to allow compressor bypass to occur when the device 52 is at or near an opened position, but cause recirculation to occur when the device 52 is at or near a closed position. When the device 52 slides to a closed position or a point near a closed position the throttle valve aspect 26 can be utilized, but there can be a buildup of backpressure between the device 52 and the compressor wheel 28. This can cause damage to the compressor wheel 28 if left unresolved. [0035] In order to stabilize the back-pressure, the recirculation-bypass valve aspect 46 can be used. The recirculation-bypass valve aspect 46 can include using the device 52 and regulating mechanism 53 to allow the fluid between the compressor 28 and the device 52 to flow through the recirculation-bypass channel 44. This can recirculate air from the output side 206 of the compressor 28 to the input side of the compressor 28. The recirculation-bypass channel 44 can recirculate fluid back to the inlet 58 or an area proximate the inlet 58. The recirculation bypass channel 44 can be formed within the housing 29 or it can be external. Recirculating the pressurized air through the recirculation-bypass channel 44 can increase the internal mass flow through the compressor 28 without increasing the flow past the device 52.

[0036] The flow through the recirculation-bypass channel 44 can be controlled by a recirculation-bypass valve aspect 46 of the air device 33. When the recirculation-bypass valve aspect 46 is open the amount of air flow through the recirculation-bypass channel 44 can be increased and when the recirculation- bypass valve aspect 46 is closed, the amount of air flow through the recirculation- bypass channel 44 can be decreased. The recirculation-bypass valve 46 aspect and the recirculation bypass channel 44 can be inside the compressor housing 29 which reduces or compacts the envelope or size for the compressor 28, the recirculation-bypass channel 44, and the recirculation-bypass valve aspect 46. In another embodiment, the recirculation-bypass channel 44 and a separate recirculation-bypass valve can be outside of the compressor housing 29.

[0037] The device 52 can be controlled by an actuator 62 to operate over the entire operating range of the air device valve 52 and the recirculation-bypass channel 44, where the actuator 62 has the necessary force to close the device 52 against the forces of the air flow. In another embodiment, the device 52 and the recirculation-bypass channel 44 can be operated by separate actuators (not shown), but this embodiment may require an increase in material and space. In addition, the device 52 can be forced balanced. [0038] With reference now to Fig. 6, a two stage turbocharged diesel engine is illustrated depicting another embodiment 1 10 with inventive aspects of the present disclosure. The system 110 can include an engine 112 and exhaust gas manifold 116, as well as an intake manifold 114. A high pressure EGR path 146 can deliver exhaust gas from exhaust manifold 116 to an intake path 140 that leads to an intake manifold 114 of the engine. The exhaust gas that enters the EGR path 146 can first pass through an EGR cooler 148 in order to reduce the temperature of the exhaust gas, and can then pass through an EGR valve 150. A path 18 from the exhaust manifold 1 16 can lead to a high pressure turbine 120 or a turbine bypass channel 160 or first channel with a bypass valve 162 for controlling the flow of fluid through the bypass channel 160. The bypass channel 160 can be formed in part of the housing of the turbine 120 or it can be a separate channel. The bypass valve 162 and the bypass channel 160 can function to selectively divert the flow of some or all of the fluid around the turbine 120. Fluid leaving the outlet of the first turbine 120 or bypass channel 160 can then be introduced to a second turbine 164 or a second turbine bypass channel 166 with a bypass valve 168 that can divert some or all of the fluid around the second turbine 164. The second bypass channel 160 and bypass valve 168 can be formed in a housing that contains the second turbine 164 or it can be a separate component.

[0039] In one embodiment, the turbines 120, 164, bypass channels 160, 166 and bypass valves 162, 168 can be arranged in a single cast housing. After fluid passes through the outlet of the second turbine 164 or second bypass channel 160, a filter 122 can clean soot from the existing fluid which is then delivered to an exhaust throttle and EGR valve system 124. The exhaust gas can exit and be delivered to the exhaust pipe 126 and/or can be directed to an EGR path 142 which includes an EGR cooler 144. Gas to be recompressed can then be mixed with fresh air from inlet 128. Upstream from the inlet pipe 128 can be a low pressure compressor 170 and a high pressure compressor 28. A third air device 33, similar to the one depicted in Figs. 5, 7 and 8, can be used and like reference numbers can be used to designate similar or identical components. The recirculation-bypass channel 44 can include the device 52 which is operable to bypass mixed gas around a rotatable wheel or compressor 28. A charge air cooler 136 can cool the compressed gas prior to entry to an inlet 140 to the intake manifold 1 14.

[0040] It will be appreciated that the turbines 120 and 164 and/or the compressors 28 and 178 can be of a fixed geometry or a variable geometry configuration. It will also be appreciated that turbine bypass valves 162 and 168 can be eliminated, if so desired. It will also be appreciated that compressor 28 can be of smaller dimensions than compressor 170, if so desired. A brief description of the operation of the two stage system 110 will now be presented. Under certain operating conditions, the high mass flow from the compressor 170 can cause over speeding of the compressor 28. This can occur for various reasons, such as in an embodiment where the compressor 170 is larger than the compressor 28 which can cause the over speeding. The bypass-recirculation channel 44 can address this problem. In the event of a high mass flow through the compressor 170, the device 52 can be opened, so that all or a substantial amount of the compressed air by the compressor 170 can bypass the compressor 28 through the bypass- recirculation channel 44 in order to avoid creating a high pressure drop through the compressor (i.e., running the compressor to the right of the choke line). Opening device 52 at very high mass flows can avoid over speeding of the compressor 28. The flow of gas through the two stage system 1 10 can be essentially the same as that discussed above concerning system 10, and will therefore, not be repeated herein. It will be appreciated that the low pressure compressor 170 can have an internal throttle valve and recirculation-bypass system.

[0041] While the present disclosure has been described with respect to a turbocharger having variable geometry guide vanes, it should be understood that the exemplary embodiment can be used with other types of turbochargers. It is also contemplated by the present disclosure that the exemplary embodiment can be used with other types of fluid impelling devices that are subjected to inefficiencies due to turbulent and/or swirling inlet flow. Such other fluid impelling devices include, but are not limited to, the following: superchargers; centrifugal pumps; centrifugal fans; single-stage gas compressors; multistage gas compressors; and other kinds of devices which generally use one or more rotating elements to compress gases and/or induce fluid flow.

[0042] While the invention has been described by reference to a specific embodiment chosen for purposes of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the spirit and scope of the invention.

Claims

CLAIMS:

1. A control device (10, 110) for providing a compressed fluid to an engine (12, 112), the device comprising: a housing (33); a compressor (28, 170) in fluid communication with a source of fluid and the engine (12, 112), the compressor (28, 170) having an inlet (58) and an outlet, the compressor (28, 170) being positioned in the housing (33); and a flow controller (52) in fluid communication with the inlet (58) and outlet of the compressor (28, 170), wherein the flow controller (52) selectively opens to return at least some of the compressed fluid from the outlet of the compressor (28, 170) to the inlet (58) of the compressor (28, 170), opens to direct at least some of the fluid directly to the engine (12, 112) and bypassing the compressor (28, 170), and closes so that all fluid passes through the compressor.

2. The control device (10, 110) of claim 1 , wherein the flow controller (52) selectively provides all of the fluid to the compressor (28, 170) and the engine (12, 112).

3. The control device (10, 110) of claim 1 , wherein the flow controller (52) comprises a control channel (44) and a valve (26, 46, 53), and wherein the control channel (44) provides fluid communication between the inlet (58) of the compressor (28, 170) and the valve (26, 46, 53).

4. The control device (10, 110) of claim 1 , wherein the flow controller (52) is positioned in the housing (33).

5. The control device (10, 110) of claim 1 , wherein the flow controller (52) has a slidable collar (26, 46, 53), wherein the compressor (28, 170) is a compressor wheel positioned in the housing (33) and the slidable collar (26, 46, 53) circumscribes the compressor wheel, and wherein the slidable collar (26, 46, 53) is operable to move between opened and closed positions.

6. The control device (10, 110) of claim 1 , wherein the flow controller (52) has a regulator valve (26, 46, 53) that allows flow in a first and second direction, wherein the first direction provides the compressed fluid from the outlet of the compressor (28, 170) to the inlet (58) of the compressor (28, 170), and wherein the second direction provides the fluid from the inlet (58) of the compressor (28, 170) to the outlet of the compressor (28, 170).

7. The control device (10, 110) of claim 1 , wherein the flow controller (52) has a slidable collar (26, 46, 53) and a regulator valve (26, 46, 53), wherein the compressor (28, 170) is a compressor wheel positioned in the housing (33) and the slidable collar (26, 46, 53) circumscribes the compressor wheel, wherein the slidable collar (26, 46, 53) is operable to move between opened and closed positions, wherein the regulator valve (26, 46, 53) allows flow in a first and second direction, wherein the first direction provides the compressed fluid from the outlet of the compressor (28, 170) to the inlet (58) of the compressor (28, 170), and wherein the second direction provides the fluid from the inlet (58) of the compressor (28, 170) to the outlet of the compressor (28, 170).

8. A multi-stage turbocharger system comprising: an engine (12, 112) having an intake manifold (14, 114) and an exhaust manifold (16, 116); a first turbine (16, 120, 164) positioned downstream of said exhaust manifold

(16, 116), the first turbine (16, 120, 164) having an inlet for receiving exhaust gas from the exhaust manifold (16, 1 16) and an outlet for providing the exhaust gas downstream; a second turbine (16, 120, 164) downstream of said first turbine (16, 120, 164) and having an inlet and an outlet, the inlet of the second turbine (16, 120, 164) receiving the exhaust gas from the first turbine (16, 120, 164); a compressor (28, 170) having an inlet (58) and an outlet, the inlet (58) of the compressor (28, 170) being in fluid communication with a source of fluid and being driven by one of the first or second turbines (16, 120, 164); and a flow control device upstream of said intake manifold (14, 114) and having a flow controller (52) with an inlet and outlet, the outlet of the flow controller (52) being in fluid communication with the intake manifold (14, 1 14), the inlet of the flow controller (52) being in fluid communication with both the inlet (58) and outlet of the compressor (28, 170), wherein the flow controller (52) selectively bypasses the fluid around the compressor (28, 170) and recirculates compressed fluid from the outlet of the compressor (28, 170) to the inlet (58) of the compressor (28, 170).

9. The system of claim 8, further comprising a housing (33) that contains the compressor (28, 170) and the flow control device.

10. The system of claim 9, wherein the flow controller (52) selectively provides all of the fluid to the compressor (28, 170) and the engine (12, 112).

11. The system of claim 9, wherein the flow controller (52) has a slidable collar (26, 46, 53), wherein the compressor (28, 170) is a compressor wheel positioned in the housing (33) and the slidable collar (26, 46, 53) circumscribes the compressor (28, 170) wheel, and wherein the slidable collar (26, 46, 53) is operable to move between opened and closed positions.

12. The system of claim 9, wherein the flow controller (52) has a regulator valve (26, 46, 53) that allows flow in a first and second direction, wherein the first direction provides the compressed fluid from the outlet of the compressor (28, 170) to the inlet (58) of the compressor (28, 170), and wherein the second direction provides the fluid from the inlet (58) of the compressor (28, 170) to the outlet of the compressor (28, 170).

13. The system of claim 9, wherein the flow controller (52) has a slidable collar (26, 46, 53) and a regulator valve (26, 46, 53), wherein the compressor (28, 170) is a compressor wheel positioned in the housing (33) and the slidable collar (26, 46, 53) circumscribes the compressor wheel, wherein the slidable collar (26, 46, 53) is operable to move between opened and closed positions, wherein the regulator valve (26, 46, 53) allows flow in a first and second direction, wherein the first direction provides the compressed fluid from the outlet of the compressor (28, 170) to the inlet (58) of the compressor (28, 170), and wherein the second direction provides the fluid from the inlet (58) of the compressor (28, 170) to the outlet of the compressor (28, 170).

14. The system of claim 9, further comprising a first valve (162, 168) and channel (160, 166) that selectively bypass the first turbine (16, 120, 164).

15. The system of claim 14, further comprising a second valve (162, 168) and channel (160, 166) that selectively bypass the second turbine (16, 120, 164).

16. The system of claim 9, further comprising a high pressure EGR path (18, 146) operably connected to said exhaust manifold (16, 116) and said intake manifold (14, 114).

17. The system of claim 9, further comprising a low pressure compressor (28, 170) that is the source of fluid.

18. A method of managing flow of a fluid to an engine (12, 1 12), the method comprising: providing a source of fluid; compressing the fluid using a compressor wheel of a compressor (28, 170); and selectively recirculating the compressed fluid to an inlet (58) of the compressor (28, 170) and bypassing the fluid to the engine (12, 1 12) around the compressor (28, 170) using a single flow control device (52).

19. The method of claim 18, further comprising providing all of the fluid from the source of the fluid to the compressor (28, 170) and the engine (12, 112) when the single flow control device is in an unactuated state.

20. The method of claim 18, further comprising positioning the single flow control device in a housing (33) with the compressor wheel (28, 170).