Turbine control for improved dosing

Abstract

A method of operating an exhaust system for an internal combustion engine is disclosed. The exhaust system includes: a turbine; a dosing module configured to deliver an after-treatment fluid to the exhaust gas at a location downstream of the turbine wheel; and at least one of a variable geometry mechanism configured to control a flow of exhaust gas delivered to the turbine wheel and a bypass control valve configured to bypass a portion of the exhaust gas. The method includes determining a current characteristic of exhaust gas at a location downstream of the turbine wheel; determining a difference between a current characteristic of the exhaust gas at a position downstream of the turbine wheel and a reference characteristic of the exhaust gas at a position downstream of the turbine wheel; in response to the difference, the at least one of the variable geometry mechanism and the bypass control valve is adjusted.

Description

Technical Field

[0001] The present disclosure relates to a method of operating an exhaust system, an exhaust system, a controller, a turbocharger system, and an engine apparatus. Background Art

[0002] Turbochargers are used in internal combustion engine systems to increase the intake pressure of the air entering the engine to a pressure above atmospheric pressure. This is called "boosting". By increasing the intake pressure of the air entering the engine, the engine is able to obtain more oxygen to support the combustion of a larger amount of fuel, thereby increasing the amount of power produced by the engine.

[0003] A turbocharger includes a compressor and a turbine. The compressor includes a compressor impeller configured to transfer energy to an incident fluid flow, and the turbine includes a turbine impeller configured to extract energy from the incident fluid flow. The compressor impeller and the turbine impeller are attached to opposite ends of the turbocharger shaft so that the two rotate together. The compressor receives intake air from the atmosphere and delivers the intake air to the intake manifold of the internal combustion engine. The turbine receives exhaust gas from the exhaust manifold of the internal combustion engine and delivers the exhaust gas to the aftertreatment system. During use, the exhaust gas leaving the internal combustion engine passes through the turbine, causing the turbine impeller to rotate. The rotation of the turbine impeller drives the compressor impeller, which acts to compress the intake air as it is delivered to the intake manifold.

[0004] The exhaust gas emitted from an internal combustion engine contains substances that are harmful to the environment. Most countries have vehicle emission standards that limit the amount of such substances that an internal combustion engine system is allowed to emit. Therefore, modern internal combustion engine systems include exhaust aftertreatment systems that are designed to remove harmful substances from the exhaust gas.

[0005] Typically, the exhaust aftertreatment system will include a particulate filter and one or more catalytic reducers. The particulate filter removes heavy combustion products, such as soot, from the exhaust. The catalytic reducer removes harmful substances, such as nitrogen oxides (NOx), from the exhaust. The catalytic reducer typically includes a large number of narrow passages made of selected materials to support the chemical reaction of removing NOx from the exhaust. The narrow passages provide a larger surface area for the catalytic reaction to occur. Several catalytic reducers are available on the market, such as two-way catalytic reducers, three-way catalytic reducers, diesel oxidation catalytic reducers (DOCs), and selective catalytic reducers (SCRs). DOCs and SCRs are typically used in diesel engine systems. Specifically for SCR, in order for the SCR reaction to work, the exhaust aftertreatment fluid must be mixed with the exhaust before the exhaust enters the catalytic reducer. The exhaust aftertreatment fluid is typically about 30% to 35% urea (CO(NH 2 )2 ) and about 65% to 70% by volume of deionized water (H 2 Exhaust aftertreatment fluids are commonly known as diesel exhaust fluid (DEF) and are commonly sold under the registered trademark AdBlue.

[0006] Traditionally, DEF is mixed with the exhaust gas in a decomposition chamber. DEF is injected into the decomposition chamber using a dosing module. In the decomposition chamber, heat is exchanged from the exhaust gas to the DEF, which causes the water in the DEF to evaporate and the urea to thermally decompose into the reducing agent ammonia (NH 3 ) and isocyanic acid (HNCO).

[0007] A typical decomposition chamber comprises a relatively large cross-sectional area compared to the width of a standard exhaust pipe. The exhaust gas entering the decomposition chamber expands, causing the exhaust gas velocity to decrease and the pressure of the exhaust gas to increase. This rapid expansion of the exhaust gas causes the formation of a turbulent vortex. DEF is then injected into the decomposition chamber, and the turbulent vortex then causes the DEF to mix with the exhaust gas. The heat exchange between the exhaust gas and the DEF causes the urea in the DEF to decompose into a reductant, and the mixture of the reductant and the exhaust gas is then delivered to the SCR.

[0008] If the exhaust and DEF are not mixed well enough, the heat exchange between the DEF and the exhaust will not be sufficient to decompose the DEF into the required reductants. In addition, poor mixing means that the reductants are not evenly distributed in the flow, and therefore certain passages of the catalytic reducer will not receive enough reductants to support the SCR reaction. In order to ensure adequate mixing, the decomposition chamber typically includes a mixing plate configured to produce additional turbulence. However, the additional turbulence caused by the mixing plate and the fluid friction exerted by the mixing plate on the exhaust gas create back pressure on the exhaust gas in the decomposition chamber. This back pressure is transmitted upstream and acts to increase the pumping work required by the internal combustion engine, and thus reduces the overall efficiency of the engine system. Therefore, there is a need to improve this technical field.

[0009] Injecting DEF into the exhaust may also result in operational challenges. For example, injecting DEF presents a risk of deposits accumulating in the exhaust system if the DEF is not thoroughly mixed with the exhaust. Similarly, certain engine operating regimes may reduce the likelihood that the DEF will be thoroughly mixed with the exhaust during operation, and therefore increase the risk of deposits accumulating in the exhaust system. The accumulation of deposits presents a risk of increasing back pressure on the system, and therefore a risk of operating the exhaust system reliably and efficiently.

[0010] There exists a need to provide an alternative system that overcomes one or more disadvantages of known systems (whether or not mentioned in this document). Summary of the invention

[0011] According to a first aspect of the present disclosure, there is provided a method of operating an exhaust system for receiving exhaust from an internal combustion engine, the exhaust system comprising: a turbine configured to receive exhaust from the internal combustion engine, the turbine comprising a turbine wheel configured to extract energy from the exhaust; a dosing module configured to deliver an aftertreatment fluid to the exhaust at a location downstream of the turbine impeller; at least one of a variable geometry mechanism configured to control exhaust flow delivered to the turbine impeller and a bypass control valve configured to bypass a portion of the exhaust from a location upstream of the turbine impeller to a location downstream of the turbine impeller; and a controller configured to perform the method, the method comprising: determining a current characteristic of the exhaust at a location downstream of the turbine impeller; determining a difference between a current characteristic of the exhaust at the location downstream of the turbine impeller and a reference characteristic of the exhaust at the location downstream of the turbine impeller; and adjusting at least one of the variable geometry mechanism and the bypass control valve in response to the difference.

[0012] Adjusting the variable geometry mechanism may involve changing the position of one or more flow influencing elements of the variable geometry mechanism, such as the angular position and / or angle of one or more nozzle vanes relative to the axis of the turbine (e.g., in a so-called "swinging vane" variable geometry mechanism), and / or adjusting the axial position of the nozzle ring and / or shroud plate to change the width of an annular inlet passage configured to direct exhaust gas into an inlet guide vane portion of the turbine wheel (e.g., in a so-called "sliding wall" variable geometry mechanism).

[0013] The bypass control valve may be a valve of any suitable valve device capable of bypassing a portion of the exhaust gas from a position upstream of the turbine impeller to a position downstream of the turbine impeller. For example, the bypass control valve may be formed integrally with the turbine (e.g., in the form of a wastegate), may be external to the turbine (e.g., in the form of an external bypass), or may form part of an integrated valve system (e.g., a rotary control throttle valve) for throttling the flow to the turbine and / or directing the exhaust gas for exhaust gas recirculation to the engine inlet. The bypass control valve may be a rotary valve, a flap valve, a poppet valve, or other type of valve. Adjusting the bypass control valve may include: changing the position of the bypass control valve to change the amount of fluid allowed to travel from one side of the bypass control valve to the other side. The exhaust system may include a bypass channel in which the bypass control valve is positioned. The bypass control valve and the bypass control channel are configured to allow the exhaust gas to travel from a position upstream of the turbine to a position downstream of the turbine without traveling through the turbine impeller. The bypass passage and / or bypass control valve may be integrated into the turbine housing of the turbine (in a so-called "wastegate" arrangement), or may be unintegrated with the turbine housing.

[0014] The exhaust gas may encompass the products of combustion exhausted from an internal combustion engine. This may include, for example, carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxides, lead, particulate matter, and the like. An aftertreatment fluid may include any fluid that may be used in conjunction with a catalyst to treat the exhaust gas to reduce one or more of the products of combustion. This may include, for example, hydrocarbons, and in particular fuels such as gasoline or diesel used with an oxidation catalyst, and may additionally or alternatively include ammonia, or a mixture of ammonia and water, for example in a ratio of 67.5% by volume of water to 32.5% by volume of urea (sometimes referred to as diesel exhaust fluid (DEF), typically sold under the registered trademark AdBlue), for use with a selective catalytic reduction (SCR) catalyst.

[0015] Determining the current characteristic of the exhaust gas may involve measuring, directly or indirectly, the amount of one or more physical characteristics of the exhaust gas. Direct measurement may involve the use of a sensor exposed within the exhaust gas flow, the sensor being configured to output a signal indicative of the amount of a physical characteristic of the exhaust gas, such as temperature, velocity, pressure, etc. Indirect measurement may involve a process in which the amount of a physical characteristic is inferred from information received regarding one or more other physical characteristics that have a physical relationship to the amount of the characteristic being inferred. For example, a formula or lookup table stored within a controller may be used to infer the current characteristic from one or more direct measurements of other characteristics. Described in another way, the current characteristic may be obtained indirectly.

[0016] The dosing module may deliver the aftertreatment fluid into the exhaust gas at a location downstream of the turbine impeller such that it produces an exhaust gas mixture. The exhaust gas mixture may encompass a mixture of the exhaust gas and the aftertreatment fluid, and in particular a mixture of the exhaust gas and the aftertreatment fluid that has not yet decomposed into a reductant, such as a mixture of the exhaust gas and urea and / or water vapor. The current characteristic may be a current characteristic of the exhaust gas mixture, and the reference characteristic may be a reference characteristic of the exhaust gas mixture.

[0017] Determining the current characteristic may include measuring the amount of the characteristic. For example, determining the current characteristic may include directly measuring the amount of the characteristic using, for example, a sensor.

[0018] Determining the current characteristic may include measuring quantities of one or more characteristics of an internal combustion engine system in which the exhaust system is incorporated; processing the measured one or more quantities in a computing operation; and inferring the current characteristic of the exhaust from the computing operation. The one or more characteristics of the exhaust may be physical characteristics different from the characteristic being determined, or may be a mixture of physical characteristics that are the same and different from the characteristic being determined. The computing operation may involve receiving the measured one or more quantities as inputs in the operation of a mathematical formula stored in a memory of the controller, and / or as inputs in the operation of a data set (e.g., one or more so-called "lookup" tables) stored in a memory of the controller. The one or more characteristics measured as part of the step of determining the current characteristic may be characteristics of the exhaust, however in other embodiments, the one or more characteristics measured as part of the step of determining the current characteristic may be any relevant characteristic of the internal combustion engine system. Measuring quantities of one or more characteristics of the exhaust and / or mixture may include measuring quantities of one or more physical characteristics of the exhaust and / or mixture.

[0019] Measuring one or more characteristics of the exhaust gas may include measuring one or more of: turbine inlet pressure; turbine inlet temperature; turbine outlet pressure; turbine outlet temperature; engine speed; throttle position; engine air mass flow; engine inlet pressure; engine inlet temperature; NOx concentration; catalyst gas temperature; engine fuel flow; engine air flow; engine boost pressure; engine load; engine cylinder temperature; engine cylinder pressure; engine fuel pressure or turbine rotation rate.

[0020] The turbine inlet pressure or temperature may be the pressure or temperature of the exhaust gas within the inlet of the turbine, for example, immediately upstream of the turbine impeller, within a housing configured to direct the exhaust gas to the turbine impeller (e.g., in a volute), or within a duct immediately upstream of such a housing and leading to such a housing.

[0021] The turbine outlet pressure or temperature can be the pressure or temperature of the exhaust and / or mixture within the outlet of the turbine, for example, immediately downstream of the turbine impeller, within a housing configured to receive the exhaust from the turbine impeller (e.g., in an axial duct or diffuser), or within a downcomer immediately downstream of such a housing.

[0022] Typically, pressure may be measured using a pressure sensor (eg, a pitot tube or other such sensor in communication with the exhaust gas flow). Temperature may be measured using a thermometer, temperature sensitive switch, etc. in communication with the exhaust gas flow.

[0023] The engine speed may be the rotational rate of the engine. The engine speed may be measured, for example, using a tachometer, etc. The engine load may be the load applied to the engine by a system incorporating the engine, such as a vehicle load, etc.

[0024] The throttle position may be the angular position of a throttle valve (e.g., a throttle on the intake and / or exhaust side of the engine). The engine air mass flow rate may be the mass flow rate of air entering the engine. The engine inlet pressure or temperature may be, for example, the pressure or temperature of the air entering the engine in the inlet manifold. The throttle position, engine mass flow rate, engine inlet pressure, and engine inlet temperature may be used to infer engine load. The engine load may be processed in conjunction with one or more measured characteristics of the exhaust gas in the calculation operation to infer the current characteristics of the exhaust gas.

[0025] The current characteristic of the exhaust gas may include a current temperature profile of the exhaust gas, and the reference characteristic of the exhaust gas may include a reference temperature profile of the exhaust gas. The temperature profile of the mixture of the exhaust gas and the aftertreatment fluid may include: a temperature at a single spatial location within the mixture, and / or a distribution of temperatures across multiple spatial locations within the mixture, and / or an average temperature across multiple spatial locations within the mixture. The temperature profile may be a temperature profile of the exhaust gas mixture. Determining the current characteristic of the exhaust gas at a location downstream of the turbine impeller may include determining a temperature profile of the exhaust gas at a location downstream of the turbine impeller.

[0026] Determining a difference between a current characteristic of the exhaust at a location downstream of the turbine impeller and a reference characteristic of the exhaust at a location downstream of the turbine impeller may include determining a difference between a temperature curve at a location downstream of the turbine impeller and a reference temperature curve at a location downstream of the turbine impeller.

[0027] The current temperature profile of the exhaust gas may be determined based on one or more of: a current NOx reduction across one or more catalytic converters; an inlet exhaust gas temperature of the aftertreatment device; an outlet exhaust gas temperature of the aftertreatment device; a temperature of the exhaust gas within the aftertreatment device; and an excess energy ratio (EER). A catalytic converter may be an example of an aftertreatment device. The EER is the ratio of the total energy available in the exhaust gas divided by the energy required to completely decompose the aftertreatment fluid entrained by the exhaust gas. The EER may be expressed as the heat energy of the exhaust gas divided by the sum of the heating energy and evaporation energy of water and the heating energy and evaporation energy of urea.

[0028] If a breakup rate of aftertreatment fluid droplets in the exhaust flow falls outside an acceptable range and / or if an activation time of the aftertreatment device falls outside an acceptable range, the at least one of the variable geometry mechanism and the bypass control valve may be adjusted to increase a temperature of the exhaust gas at a core of the exhaust flow.

[0029] If the risk of deposit accumulation falls outside of an acceptable range, the at least one of the variable geometry mechanism and the bypass control valve may be adjusted to increase the temperature of the exhaust gas at the periphery of the exhaust flow.

[0030] The current characteristic of the exhaust gas may include a current velocity profile of the exhaust gas, and the reference characteristic of the exhaust gas may include a reference velocity profile of the exhaust gas. The velocity profile of the exhaust gas may encompass: the velocity of a single spatial location within a mixture, and / or the distribution of velocities across multiple spatial locations within a mixture, and / or the average velocity across multiple spatial locations within a mixture. The velocity profile may be a velocity profile of an exhaust gas mixture.

[0031] Determining a current characteristic of the exhaust gas at a location downstream of the turbine impeller may include determining a velocity profile of the exhaust gas at the location downstream of the turbine impeller. Determining a difference between a current characteristic of the exhaust gas at the location downstream of the turbine impeller and a reference characteristic of the exhaust gas at the location downstream of the turbine impeller may include determining a difference between a velocity profile at the location downstream of the turbine impeller and a reference velocity profile at the location downstream of the turbine impeller.

[0032] Determining the current characteristics of the exhaust gas may be based on one or more of: a pressure ratio across the turbine; turbine inlet pressure; turbine outlet pressure; turbine inlet temperature; turbine outlet temperature; turbine rotation rate, and engine mass flow.

[0033] If the risk of deposit accumulation falls outside the acceptable range, at least one of the variable geometry mechanism and the bypass control valve can be adjusted to change the velocity curve at the position downstream of the turbine impeller. Specifically, if the risk of deposit accumulation falls outside the acceptable range, at least one of the variable geometry mechanism and the bypass control valve can be adjusted to a configuration corresponding to the velocity curve that reduces the risk of deposit accumulation, or adjusted toward a configuration corresponding to the velocity curve that reduces the risk of deposit accumulation. This can be a velocity curve with an increased velocity in one or more regions of interest, and an associated increase in swirl and / or shear stress and / or convective heat transfer. The risk of deposit accumulation falling outside the acceptable range can indicate that there are one or more zones in the exhaust passage where there is an increased risk of aftertreatment fluid impact that may cause deposit solidification. The risk of deposit accumulation falling outside the acceptable range can be quantified by the back pressure on the exhaust system or turbine, and more specifically, the increase exceeds an acceptable level. An example of quantifying risk based on the back pressure across the exhaust system or turbine includes: determining a percentage increase relative to the nominal back pressure at a given engine operating point. By monitoring the backpressure with reference to a given flow rate, perhaps by using a lookup table or the like, it can be determined whether the backpressure is higher than expected (indicating deposit accumulation). If the backpressure is, for example, 10% or more higher than the expected (nominal) backpressure, the risk of deposit accumulation can be considered to be outside an acceptable range for a given flow rate. Alternatively, a specific pressure rise, such as a rise of 3 kPa above the nominal or expected pressure, can indicate that the risk of deposit accumulation falls outside an acceptable range. The level of deoxygenation can also indicate that the risk of deposit accumulation falls outside an acceptable range. A lack of NOx conversion (i.e., a relatively low level of deoxygenation) can indicate an undesirable uniformity index (UI) of the aftertreatment fluid in the exhaust (which in turn can indicate an increased risk of deposit accumulation). For example, a deoxygenation level of less than about 87% can indicate an increased risk of deposit accumulation.

[0034] Changing the velocity profile at a location (eg, region) downstream of the turbine wheel may include one or more of: changing the velocity of the exhaust gas; changing the swirl angle of the exhaust gas; and changing the shear stress applied by the exhaust gas.

[0035] The position downstream of the turbine impeller can be the location of the dosing module. The position downstream of the turbine impeller can be downstream of the dosing module. The position can be a bend (e.g., at least a partially arcuate portion of the turbine outlet passage), specifically the interior of the bend. The position can be an impact zone (e.g., generally opposite the dosing module). The position can be a joint between components, such as a bellows or a flexible tube (e.g., having a corrugated or wrinkled surface). The position can be any region with a step change transition (e.g., not a smooth transition) where vortices are likely to form. The position can be an expansion joint. The position can be one or more of the above positions (e.g., multiple different positions can be targeted). Alternatively, a single position can be targeted.

[0036] The method can further include: identifying the presence of operating conditions of the exhaust system that produce an insufficient swirl angle of the exhaust in the turbine outlet passage based on the difference; and in response to identifying the operating conditions, adjusting at least one of the variable geometry mechanism and the bypass control valve to increase the swirl angle of the exhaust in the turbine outlet passage. The step of identifying the presence of operating conditions of the exhaust system that produce an insufficient swirl angle of the exhaust around the centerline of the turbine outlet passage can include determining whether the amount of the difference between the current characteristic and the reference characteristic falls outside an acceptable range or threshold.

[0037] Adjusting the variable geometry mechanism to increase the swirl angle of the exhaust in the turbine outlet passage can include moving the variable geometry mechanism to a configuration corresponding to the maximum swirl angle of the exhaust in the turbine outlet passage, or moving towards a configuration corresponding to the maximum swirl angle of the exhaust in the turbine outlet passage.

[0038] Adjusting the bypass control valve to increase the swirl angle of the exhaust in the turbine outlet passage can include moving the bypass control valve to a configuration corresponding to the maximum swirl angle of the exhaust in the turbine outlet passage, or moving towards a configuration corresponding to the maximum swirl angle of the exhaust in the turbine outlet passage.

[0039] The current characteristic of the exhaust gas may include a current NOx reduction across one or more catalytic converters, and the reference characteristic of the exhaust gas may include a reference NOx reduction across the one or more catalytic converters. The NOx reduction may be a measurement of a relative proportion of NOx that has been reduced on one or more catalytic converters. This may be based on a difference in NOx concentration measured by a NOx sensor upstream of one or more catalytic converters (e.g., in a turbine outlet passage) and a NOx sensor positioned downstream of the one or more catalytic converters. The one or more catalytic converters may include one or more SCR catalysts.

[0040] When the NOx reduction across the one or more catalytic converters drops below about 98%, about 95%, or about 90%, an operating condition of the exhaust system that produces insufficient exhaust swirl momentum about the centerline of the turbine outlet passage can be identified. When the NOx reduction decreases, this can indicate that the amount of swirl momentum in the turbine outlet passage is insufficient to provide sufficient mixing of the exhaust gas with the aftertreatment fluid to decompose the aftertreatment fluid. Increasing the amount of bypass delivered to the turbine outlet passage can increase the amount of swirl momentum in the turbine outlet passage, thereby increasing mixing between the exhaust gas and the aftertreatment fluid, resulting in improved decomposition, and providing more reductant at one or more catalytic converters to increase the amount of NOx reduced or reduced by one or more catalytic converters.

[0041] The current characteristic of the exhaust gas may include a turbine efficiency, and the reference characteristic of the exhaust gas may include a reference turbine efficiency. When the turbine is operating at maximum efficiency, the flow in the turbine outlet may be substantially laminar and axial, with little swirl momentum. This may result in poor aftertreatment fluid decomposition, and a decrease in the amount of NOx reduced by the exhaust system. Increasing the amount of bypass delivered to the turbine outlet passage may increase the amount of swirl momentum in the turbine outlet passage, thereby improving mixing, decomposition, and thus resulting in NOx reduction.

[0042] An operating condition of the exhaust system that produces insufficient exhaust swirl momentum about the centerline of the turbine outlet passage may be identified when the turbine efficiency is at least about 70%, about 80%, about 90% or about 95% of the maximum efficiency of the turbine.

[0043] The method may also include identifying, based on the difference, the presence of an operating condition of the exhaust system in which insufficient shear stress is applied by the exhaust gas to a wall of the exhaust system at a specific location; and in response to identifying the operating condition, adjusting at least one of the variable geometry mechanism and the bypass control valve to increase an amount of shear stress applied by the exhaust gas to the wall of the exhaust system at the specific location.

[0044] Adjusting the variable geometry mechanism to increase the amount of shear stress applied by the exhaust gas to the wall of the exhaust system at the particular location may include moving the variable geometry mechanism to, or toward, a configuration corresponding to a maximum shear stress of the exhaust gas at the particular location.

[0045] Adjusting the bypass control valve to increase the amount of shear stress applied by the exhaust gas to the wall of the exhaust system at the particular location may include moving the bypass control valve to or toward a configuration corresponding to a maximum shear stress of the exhaust gas at the particular location.

[0046] The current characteristic of the exhaust gas may include an excess energy ratio (EER), and the reference characteristic of the exhaust gas may include a reference excess energy ratio. The EER is the ratio of the total energy available in the exhaust gas to the energy required to completely decompose the aftertreatment fluid entrained by the exhaust gas. The EER may be expressed as the heat energy of the exhaust gas divided by the sum of the heating energy and evaporation energy of water and the heating energy and evaporation energy of urea.

[0047] When the excess energy ratio is less than about 10, about 15, or about 20, an operating condition of the exhaust system where insufficient shear stress is applied by the exhaust gas to the wall of the exhaust system at the particular location may be identified.

[0048] The current characteristic of the exhaust gas may include a turbine efficiency, and the reference characteristic of the exhaust gas may include a reference turbine efficiency. An operating condition of the exhaust system in which insufficient shear stress is applied to the wall of the exhaust system by the exhaust gas at the particular location may be identified when the turbine efficiency is at least about 70%, about 80%, about 90%, or about 95% of a maximum efficiency of the turbine.

[0049] The current characteristic of the exhaust gas may include a turbine inlet pressure, and the reference characteristic of the exhaust gas may include a reference turbine inlet pressure.

[0050] The turbine may include: a turbine outlet passage configured to receive exhaust gas from the turbine impeller, the exhaust gas received from the turbine impeller defining a turbine main flow; and a bypass passage configured to receive exhaust gas from a position upstream of the turbine impeller and deliver the exhaust gas to the turbine outlet passage, the exhaust gas received by the bypass passage defining a bypass flow, the bypass control valve configured to adjust a flow rate of the bypass flow passing through the bypass passage; wherein the turbine impeller imparts swirl momentum to the turbine main flow wherein the swirl momentum of the turbine body flow defines a positive angular direction, and wherein the bypass passage is configured to deliver the bypass flow to the turbine outlet passage in a direction that causes the bypass flow to swirl around the centerline of the turbine outlet passage in the positive angular direction; and the method may further include: based on the difference, identifying the presence of an operating condition of the exhaust system that produces insufficient exhaust swirl momentum around the centerline of the turbine outlet passage; and adjusting the bypass control valve to increase delivery of the bypass flow to the turbine outlet passage. The operating condition of the exhaust system that produces insufficient exhaust swirl momentum around the centerline of the turbine outlet passage may be identified based on the same parameters previously discussed above.

[0051] The turbine may include: a turbine outlet passage configured to receive exhaust gas from the turbine impeller, the exhaust gas received from the turbine impeller defining a turbine main flow; and a bypass passage configured to receive exhaust gas from a position upstream of the turbine impeller and deliver the exhaust gas to the turbine outlet passage, the exhaust gas received by the bypass passage defining a bypass flow, the bypass control valve being configured to adjust a flow rate of the bypass flow passing through the bypass passage; wherein the turbine impeller imparts swirl momentum to the turbine main flow, the turbine main flow The swirl momentum of the body flow defines a positive angular direction, and wherein the bypass passage is configured to deliver the bypass flow to the turbine outlet passage in a direction that causes the bypass flow to swirl in the positive angular direction around the centerline of the turbine outlet passage; wherein the method may include: based on determining the difference, identifying the existence of an operating condition of the exhaust system in which insufficient shear stress is applied to the wall of the exhaust system by the exhaust gas at a specific location; and in response to identifying the operating condition, adjusting the bypass control valve to increase the delivery of the bypass flow to the turbine outlet passage. The operating condition of the exhaust system in which insufficient shear stress is applied to the wall of the exhaust system by the exhaust gas at a specific location can be identified based on the same parameters previously discussed above. The specific location can be a wall of the turbine outlet passage.

[0052] According to a second aspect of the present disclosure, a method for operating an exhaust system for receiving and treating exhaust from an internal combustion engine is provided, the exhaust system comprising: a turbine, the turbine being configured to receive exhaust from the internal combustion engine, the turbine comprising a turbine impeller configured to extract energy from the exhaust; a dosing module, the dosing module being configured to deliver an aftertreatment fluid to the exhaust at a position downstream of the turbine impeller, wherein the dosing module is located downstream of a downstream end of the turbine impeller along a flow axis within approximately 10 times the diameter of an outlet guide valve; at least one of a variable geometry mechanism and a bypass control valve: the variable geometry mechanism being configured to control delivery to the turbine an exhaust flow from a turbine impeller; and the bypass control valve is configured to bypass a portion of the exhaust from a location upstream of the turbine impeller to a location downstream of the turbine impeller; an aftertreatment device, the aftertreatment device being located downstream of the turbine and configured to receive and process the exhaust from the turbine; and a controller, the controller being configured to perform the method, the method comprising: determining a current characteristic of the aftertreatment device; determining a difference between the current characteristic of the aftertreatment device and a reference characteristic of the aftertreatment device; and in response to the difference, adjusting at least one of the variable geometry mechanism and the bypass control valve to regenerate the aftertreatment device.

[0053] Adjusting the variable geometry mechanism may involve changing the position of one or more flow influencing elements of the variable geometry mechanism, such as the angular position and / or angle of one or more nozzle vanes relative to the axis of the turbine (e.g., in a so-called "swinging vane" variable geometry mechanism), and / or adjusting the axial position of the nozzle ring and / or shroud plate to change the width of an annular inlet passage configured to direct exhaust gas into an inlet guide vane portion of the turbine wheel (e.g., in a so-called "sliding wall" variable geometry mechanism).

[0054] Adjusting the bypass control valve may involve changing the position of the bypass control valve to change the amount of fluid that is allowed to travel from one side of the bypass control valve to the other side. The exhaust system may include a bypass passage in which the bypass control valve is positioned. The bypass control valve and the bypass control passage are configured to allow exhaust gas to travel from a position fluidly upstream of the turbine to a position fluidly downstream of the turbine without traveling through the turbine wheel. The bypass passage and / or the bypass control valve may be incorporated into the turbine housing of the turbine (in a so-called "wastegate" device), or may not be incorporated with the turbine housing.

[0055] Determining the current characteristic of the aftertreatment device may include: directly or indirectly measuring the amount of one or more physical characteristics of the aftertreatment device. Direct measurement may include the use of a sensor associated with the aftertreatment device (e.g., in communication with the aftertreatment device, inside the aftertreatment device), which is configured to output a signal indicating the amount of the physical characteristic of the aftertreatment device, such as temperature (e.g., the temperature of the wall, or the temperature of the component or surface on which the catalyst is installed). Indirect measurement may include a process in which the amount of the physical characteristic is inferred from information received related to one or more other physical characteristics, and the one or more other physical characteristics have a physical relationship with the amount of the characteristic being inferred. The current characteristic of the aftertreatment device may be based on one or more characteristics of the exhaust gas (e.g., the temperature of the exhaust gas, the pressure drop across the aftertreatment device, the reduction of NOx across the aftertreatment device, etc.). For example, a formula or lookup table stored in a controller may be used to infer the current characteristic from one or more direct measurements of other characteristics. Described in another way, the current characteristic may be obtained indirectly. The catalyst may be mounted to a monolith, such as a ceramic monolith.

[0056] The dosing module may deliver the aftertreatment fluid into the exhaust gas at a position downstream of the turbine impeller such that it produces an exhaust gas mixture. The exhaust gas mixture may encompass a mixture of the exhaust gas and the aftertreatment fluid, and in particular a mixture of the exhaust gas and the aftertreatment fluid that has not yet decomposed into a reductant, such as a mixture of the exhaust gas and urea and / or water vapor. The current characteristic of the aftertreatment system may be inferred from the current characteristic of the exhaust gas and / or the exhaust gas mixture (e.g., from the temperature of the exhaust gas mixture entering or leaving the aftertreatment device), and the reference characteristic may be a reference characteristic of the exhaust gas and / or the exhaust gas mixture.

[0057] Determining the current characteristic may include measuring the amount of the characteristic. For example, determining the current characteristic may include directly measuring the amount of the characteristic using, for example, a sensor.

[0058] Determining the current characteristic may include: measuring quantities of one or more characteristics of the internal combustion engine system in which the exhaust system is incorporated; processing the measured one or more quantities in a computing operation; and inferring the current characteristic of the exhaust from the computing operation. The one or more characteristics of the exhaust gas may be physical characteristics different from the characteristic being determined, or may be a mixture of physical characteristics that are the same and different from the characteristic being determined. The computing operation may involve: receiving the measured one or more quantities as inputs in the operation of a mathematical formula stored in a memory of the controller, and / or as inputs in the operation of a data set (e.g., one or more so-called "lookup" tables) stored in a memory of the controller. The one or more characteristics measured as part of the step of determining the current characteristic may be characteristics of the exhaust gas, however in other embodiments, the one or more characteristics measured as part of the step of determining the current characteristic may be any relevant characteristic of the internal combustion engine system.

[0059] Determining a current characteristic of the aftertreatment device may include determining a temperature of the aftertreatment device. Determining the current characteristic of the aftertreatment device may be based on one or more of: a time period since a previous regeneration event; a time period since engine ignition; a current NOx reduction on one or more catalytic converters; a turbine inlet pressure; a turbine outlet temperature and / or temperature profile; and a pressure drop across the turbine. Determining the difference between the current characteristic of the aftertreatment device and a reference characteristic of the aftertreatment device may include determining the difference between the temperature of the aftertreatment device and a reference temperature of the aftertreatment device. The temperature may be a single temperature. The temperature may be a temperature profile, including multiple temperatures across a range of spatial locations. For example, temperature readings may be recorded by multiple thermocouples disposed at different locations around or within the aftertreatment device.

[0060] The method may also include: determining whether the temperature of the aftertreatment device falls outside an acceptable range; and adjusting at least one of the variable geometry mechanism and the bypass control valve to increase the temperature of the aftertreatment device. If the temperature of the aftertreatment device falls outside an acceptable range, at least one of the variable geometry mechanism and the bypass control valve may be adjusted to a configuration corresponding to the maximum temperature of the aftertreatment device, or adjusted toward a configuration corresponding to the maximum temperature of the aftertreatment device. In the case of adjusting the bypass control valve, the bypass control valve is preferably opened, more preferably opened to a 100% open configuration, to expose the aftertreatment device to high temperature (bypass) exhaust gas to increase the temperature of the aftertreatment device. In the case of adjusting the variable geometry mechanism, the variable geometry mechanism may be adjusted to reduce the relative inlet area of ​​the turbine impeller (i.e., throttle the inlet of the turbine impeller), thereby increasing engine back pressure and pumping work, thereby increasing the temperature of the exhaust gas, and thereby exposing the aftertreatment device to high temperature exhaust gas to increase the temperature of the aftertreatment device.

[0061] According to a third aspect of the present disclosure, there is provided an exhaust system for receiving exhaust from an internal combustion engine, the exhaust system comprising: a turbine configured to receive exhaust from the internal combustion engine, the turbine comprising a turbine impeller configured to extract energy from the exhaust; a dosing module configured to deliver an aftertreatment fluid to the exhaust at a position downstream of the turbine impeller; at least one of a variable geometry mechanism and a bypass control valve, the variable geometry mechanism configured to control the exhaust flow delivered to the turbine impeller; and the bypass control valve configured to bypass a portion of the exhaust from a position upstream of the turbine impeller to a position downstream of the turbine impeller; and a controller configured to: determine a current characteristic of the exhaust at a position downstream of the turbine impeller; determine a difference between a current characteristic of the exhaust at the position downstream of the turbine impeller and a reference characteristic of the exhaust at the position downstream of the turbine impeller; and adjust at least one of the variable geometry mechanism and the bypass control valve in response to the difference.

[0062] The controller may be configured to: measure quantities of one or more characteristics of the internal combustion engine system in which the exhaust system is incorporated; process the measured one or more quantities in a computational operation; and infer the current characteristic of the exhaust gas from the computational operation.

[0063] The controller can be configured to measure one or more of: turbine inlet pressure; turbine inlet temperature; turbine outlet pressure; turbine outlet temperature; engine speed; throttle position; engine air mass flow; engine inlet pressure; engine inlet temperature; NOx concentration; catalyst gas temperature; engine fuel flow; engine air flow; engine boost pressure; engine load; engine cylinder temperature; engine cylinder pressure; engine fuel pressure; or turbine rotation rate.

[0064] The current characteristic of the exhaust gas may include a current temperature profile of the exhaust gas, and the reference characteristic of the exhaust gas may include a reference temperature profile of the exhaust gas.

[0065] The current temperature profile of the exhaust gas may be determined based on one or more of: a current NOx reduction across one or more catalytic converters; an inlet exhaust temperature to an aftertreatment device; an outlet exhaust temperature to an aftertreatment device; a temperature of the exhaust gas within the aftertreatment device; and an excess energy ratio (EER).

[0066] If a breakup rate of aftertreatment fluid droplets in the exhaust flow falls outside an acceptable range and / or if an activation time of the aftertreatment device falls outside an acceptable range, the at least one of the variable geometry mechanism and the bypass control valve may be adjusted to increase a temperature of the exhaust gas at a core of the exhaust flow.

[0067] If the risk of deposit accumulation falls outside of an acceptable range, the at least one of the variable geometry mechanism and the bypass control valve may be adjusted to increase the temperature of the exhaust gas at the periphery of the exhaust flow.

[0068] The current characteristic of the exhaust gas may include a current velocity profile of the exhaust gas, and the reference characteristic of the exhaust gas may include a reference velocity profile of the exhaust gas.

[0069] The controller may be configured to determine the current characteristic of the exhaust gas based on one or more of: a pressure ratio across the turbine; a turbine inlet pressure; a turbine outlet pressure; a turbine inlet temperature; a turbine rotation rate, and an engine mass flow rate.

[0070] If the risk of deposit accumulation falls outside of an acceptable range, the at least one of the variable geometry mechanism and the bypass control valve may be adjusted to change the velocity profile at the location downstream of the turbine impeller.

[0071] The position downstream of the turbine wheel may be the position of the dosing module. The position downstream of the turbine wheel may be downstream of the dosing module.

[0072] The controller may be configured to: identify the presence of an operating condition of the exhaust system that produces an insufficient swirl angle of the exhaust gas in the turbine outlet passage based on the difference; and in response to identifying the operating condition, adjust at least one of the variable geometry mechanism and the bypass control valve to increase the swirl angle of the exhaust gas in the turbine outlet passage.

[0073] The controller may be configured to adjust the variable geometry mechanism to increase the swirl angle of the exhaust gas in the turbine outlet passage by moving the variable geometry mechanism to, or toward, a configuration corresponding to a maximum swirl angle of the exhaust gas in the turbine outlet passage.

[0074] The controller can be configured to adjust the bypass control valve to increase the swirl angle of the exhaust gas in the turbine outlet passage by moving the bypass control valve to a configuration corresponding to a maximum swirl angle of the exhaust gas in the turbine outlet passage, or toward a configuration corresponding to a maximum swirl angle of the exhaust gas in the turbine outlet passage.

[0075] The current characteristic of the exhaust gas may include a current NOx reduction across one or more catalytic converters, and wherein the reference characteristic of the exhaust gas may include a reference NOx reduction across the one or more catalytic converters.

[0076] The controller can be configured to identify an operating condition of the exhaust system producing insufficient exhaust swirl momentum about the centerline of the turbine outlet passage when the NOx reduction across the one or more catalytic converters drops below approximately 98%, approximately 95%, or approximately 90%.

[0077] The current characteristic of the exhaust gas may include a turbine efficiency, and the reference characteristic of the exhaust gas may include a reference turbine efficiency.

[0078] The controller can be configured to identify an operating condition of the exhaust system that produces insufficient exhaust swirl momentum about the centerline of the turbine outlet passage when the turbine efficiency is at least about 70%, about 80%, about 90% or about 95% of the maximum efficiency of the turbine.

[0079] The controller can also be configured to: identify the presence of an operating condition of the exhaust system in which the exhaust applies insufficient shear stress to the wall of the exhaust system at a specific location based on the difference; and in response to identifying the operating condition, adjust at least one of the variable geometry mechanism and the bypass control valve to increase the amount of shear stress applied by the exhaust to the wall of the exhaust system at the specific location.

[0080] The controller can be configured to adjust the variable geometry mechanism to increase the amount of shear stress applied by the exhaust to the wall of the exhaust system at the specific location by moving the variable geometry mechanism to a configuration corresponding to the maximum shear stress of the exhaust at the specific location, or moving towards a configuration corresponding to the maximum shear stress of the exhaust at the specific location.

[0081] The controller can be configured to adjust the bypass control valve to increase the amount of shear stress applied by the exhaust to the wall of the exhaust system at the specific location by moving the bypass control valve to a configuration corresponding to the maximum shear stress of the exhaust at the specific location, or moving towards a configuration corresponding to the maximum shear stress of the exhaust at the specific location.

[0082] The current characteristics of the exhaust can include an excess energy ratio (EER), and the reference characteristics of the exhaust can include a reference excess energy ratio.

[0083] The controller can be configured to identify an operating condition of the exhaust system in which the exhaust applies insufficient shear stress to the wall of the exhaust system at the specific location when the excess energy ratio is less than about 10, about 15, or about 20.

[0084] The current characteristics of the exhaust can include turbine efficiency, and the reference characteristics of the exhaust can include a reference turbine efficiency.

[0085] The controller can be configured to identify an operating condition of the exhaust system in which the exhaust applies insufficient shear stress to the wall of the exhaust system at the specific location when the turbine efficiency is at least about 70%, about 80%, about 90%, or about 95% of the maximum efficiency of the turbine.

[0086] The current characteristics of the exhaust can include turbine inlet pressure, and the reference characteristics of the exhaust can include a reference turbine inlet pressure.

[0087] The turbine may include: a turbine outlet passage, the turbine outlet passage being configured to receive exhaust gas from the turbine impeller, the exhaust gas received from the turbine impeller defining a turbine main flow; and a bypass passage, the bypass passage being configured to receive exhaust gas from a position upstream of the turbine impeller and deliver the exhaust gas to the turbine outlet passage, the exhaust gas received by the bypass passage defining a bypass flow, the bypass control valve being configured to regulate the flow rate of the bypass flow passing through the bypass passage; wherein the turbine impeller imparts swirl momentum to the turbine main flow, the swirl momentum of the turbine main flow defining a positive angular direction, and wherein the bypass passage is configured to deliver the bypass flow to the turbine outlet passage in a direction causing the bypass flow to swirl in the positive angular direction around a centerline of the turbine outlet passage.

[0088] The controller may also be configured to: based on the difference, identify the presence of an operating condition of the exhaust system that produces insufficient exhaust swirl momentum about the centerline of the turbine outlet passage; and adjust the bypass control valve to increase delivery of bypass flow to the turbine outlet passage.

[0089] The controller may also be configured to: based on determining the difference, identify the presence of an operating condition of the exhaust system in which insufficient shear stress is applied by the exhaust gas to the wall of the exhaust system at a specific location; and in response to identifying the operating condition, adjust the bypass control valve to increase delivery of bypass flow to the turbine outlet passage. The specific location may be a wall of the turbine outlet passage.

[0090] According to a fourth aspect of the present disclosure, an exhaust system for receiving and treating exhaust gas from an internal combustion engine is provided, the exhaust system comprising: a turbine, the turbine being configured to receive exhaust gas from the internal combustion engine, the turbine comprising a turbine impeller configured to extract energy from the exhaust gas; a distribution module, the distribution module being configured to deliver an aftertreatment fluid to the exhaust gas at a position downstream of the turbine impeller, wherein the distribution module is located downstream of a downstream end of the turbine impeller along a flow axis within approximately 10 times the diameter of an outlet guide valve; at least one of a variable geometry mechanism and a bypass control valve: the variable geometry mechanism being configured to control the delivery an exhaust gas flow to the turbine impeller; and the bypass control valve is configured to bypass a portion of the exhaust gas from a location upstream of the turbine impeller to a location downstream of the turbine impeller; an aftertreatment device, the aftertreatment device being located downstream of the turbine and configured to receive and process the exhaust gas from the turbine; and a controller, the controller being configured to: determine a current characteristic of the aftertreatment device; determine a difference between the current characteristic of the aftertreatment device and a reference characteristic of the aftertreatment device; and in response to the difference, adjust at least one of the variable geometry mechanism and the bypass control valve to regenerate the aftertreatment device.

[0091] The controller may be configured to determine a current characteristic of the aftertreatment device by determining a temperature of the aftertreatment device.

[0092] The controller can be configured to determine the current characteristic of the aftertreatment device based on one or more of: a time period since a previous regeneration event; a time period since engine start (i.e., a "key-on" event, such as when the engine is first ignited after a period of inactivity); a current NOx reduction across one or more catalytic converters; a turbine inlet pressure; and a pressure drop across the turbine.

[0093] The controller may also be configured to determine whether a temperature of the aftertreatment device falls outside of an acceptable range and adjust the at least one of the variable geometry mechanism and the bypass control valve to increase the temperature of the aftertreatment device.

[0094] The distribution module may be located downstream of the downstream end of the turbine impeller along the flow axis within about 10 times the diameter of the outlet inducer. The distribution module may be arranged at an expanded portion of the turbine outlet passage. In particular, the distribution module may be arranged in a portion of the turbine outlet passage defining a diffuser. The distribution module may be configured to deliver a spray of the aftertreatment fluid into the diffuser.

[0095] The dosing module may be mounted to the turbine, or to a duct downstream of the turbine (e.g., a so-called "downcomer"). In particular, the dosing module may be mounted to a casing of the turbine that defines at least a portion or all of the turbine outlet passage, including, in some embodiments, a portion or all of any diffuser portion of the turbine outlet passage.

[0096] The turbine may include a turbine housing defining a turbine inlet passage and a turbine wheel chamber, and a connection adapter coupled to the turbine housing and at least partially defining the turbine outlet passage.

[0097] The dosing module may be mounted to the connection adapter.

[0098] According to a fifth aspect of the present disclosure, a turbocharger system is provided, the turbocharger system comprising: a compressor, the compressor comprising a compressor housing and a compressor impeller; a bearing housing, the bearing housing being configured to support a shaft so as to rotate around an axis; and an exhaust system according to the third or fourth aspect of the present disclosure; wherein the compressor impeller and the turbine impeller are coupled to the shaft in power communication with each other.

[0099] According to a sixth aspect of the present disclosure, there is provided an engine device, the engine device comprising an internal combustion engine and a turbocharger system according to the fifth aspect of the present disclosure; wherein the turbocharger is configured to receive exhaust gas from the internal combustion engine.

[0100] According to a seventh aspect of the present disclosure, a controller for an exhaust system receiving exhaust from an internal combustion engine is provided, the controller being configured to: determine current characteristics of the exhaust at a position downstream of a turbine impeller of a turbine of the exhaust system; determine a difference between the current characteristics of the exhaust at the position downstream of the turbine impeller and a reference characteristic of the exhaust at the position downstream of the turbine impeller; and in response to the difference, adjust at least one of the variable geometry mechanism of the turbine and the bypass control valve of the turbine.

[0101] In particular, the controller may be the same controller as the above-mentioned controller incorporated in the first aspect and the third aspect of the present disclosure. Thus, the controller may be configured to perform substantially the same method steps, and / or configured to make substantially the same determinations based on the same input parameters, and / or configured to make substantially the same adjustments to the variable geometry mechanism and / or the bypass control valve, as previously described.

[0102] According to a seventh aspect of the present disclosure, a controller for an exhaust system receiving exhaust from an internal combustion engine is provided, the exhaust system comprising: a turbine, the turbine comprising a turbine impeller; at least one of a variable geometry mechanism and a bypass control valve; and an aftertreatment device, the aftertreatment device being downstream of the turbine and configured to receive and process the exhaust from the turbine; the controller being configured to: determine a current characteristic of the aftertreatment device; determine a difference between the current characteristic of the aftertreatment device and a reference characteristic of the aftertreatment device; and in response to the difference, adjust at least one of the variable geometry mechanism of the turbine and the bypass control valve of the turbine.

[0103] In particular, the controller may be the same controller as the above-mentioned controller incorporated in the second aspect and the fourth aspect of the present disclosure. Thus, the controller may be configured to perform substantially the same method steps, and / or configured to make substantially the same determinations based on the same input parameters, and / or configured to make substantially the same adjustments to the variable geometry mechanism and / or the bypass control valve, as previously described.

[0104] The controller of the seventh and eighth aspects may be a controller for an engine system (e.g., an engine system in which an exhaust system is incorporated). In particular, the controller may be an engine control unit. However, in other embodiments, the controller may be a sub-controller of the engine system, such as an aftertreatment system controller or a turbine controller. The controller need not be a single controller, but may include a group of controllers configured to jointly provide control of the engine system and / or the exhaust system.

[0105] As the optional and / or preferred features set forth herein can be used alone or in combination with each other where appropriate, particularly in the combinations described in the appended claims. Where appropriate, the optional and / or preferred features of each aspect of the disclosure set forth herein also apply to any other aspect of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0106] Specific embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0107] Figure 1 is a schematic diagram of a known turbocharged diesel engine system;

[0108] Figure 2 is a perspective view generally viewed from above of a turbocharger including an exhaust system according to an embodiment of the present disclosure;

[0109] Figure 3 yes Figure 2 An alternative perspective view of a turbocharger;

[0110] Figure 4 yes Figure 2 and Figure 3 A side sectional view of a turbocharger;

[0111] Figure 5 yes Figures 2 to 4 An end view of a turbocharger;

[0112] Figure 6 yes Figures 2 to 5 The turbocharger passes Figure 4 An end view of the cross section taken on plane AA;

[0113] Figure 7 is a schematic block diagram of an exhaust system according to an embodiment of the present disclosure;

[0114] Figure 8 Show operation Figure 7 A schematic block diagram of a method for an exhaust system;

[0115] Fig. 9 Show Figure 8 Another embodiment of the method shown;

[0116] Fig.10 Shown schematically Figure 8 and Fig. 9 A flowchart of another embodiment of the method shown;

[0117] Fig.11 showing a plot illustrating a temperature profile of the exhaust gas at the turbine wheel nut plane for a first wastegate valve configuration;

[0118] Fig.12 showing a plot illustrating a temperature profile of the exhaust gas at the turbine wheel nut plane for a second wastegate valve configuration;

[0119] Fig.13 shows a plot illustrating a temperature profile of the exhaust gas at the turbine wheel nut plane for a third wastegate valve configuration;

[0120] Fig.14 showing a plot illustrating a temperature profile of exhaust gas at a first turbine outlet for a first wastegate valve configuration;

[0121] Fig.15 showing a plot illustrating a temperature profile of the exhaust gas at a second turbine outlet for a second wastegate valve configuration;

[0122] Fig.16 showing a plot illustrating a temperature profile of the exhaust gas at a third turbine outlet for a third wastegate valve configuration;

[0123] Fig.17 showing a plot illustrating a temperature profile at a first wall of a diffuser for a first wastegate valve configuration;

[0124] Fig.18 showing a plot illustrating a temperature profile at a second wall of the diffuser for a second wastegate valve configuration;

[0125] Fig.19 showing a plot illustrating a temperature profile at a third wall of a diffuser for a third wastegate valve configuration;

[0126] Fig. 20 Shown schematically Figure 8 and Fig. 9 A flowchart of another embodiment of the method shown;

[0127] Fig.21 showing a plot illustrating a velocity profile of exhaust gas at a turbine wheel nut plane for a first wastegate valve configuration;

[0128] Fig. 22 showing a plot illustrating a velocity profile of exhaust gas at the turbine wheel nut plane for a second wastegate valve configuration;

[0129] Fig.23 showing a plot illustrating a velocity profile of exhaust gas at the turbine wheel nut plane for a third wastegate valve configuration;

[0130] Fig.24 showing a plot illustrating a tangential velocity profile of exhaust gas at a turbine outlet for a first wastegate valve configuration;

[0131] Fig.25 showing a plot illustrating a tangential velocity profile of exhaust gas at a turbine outlet for a second wastegate valve configuration;

[0132] Fig.26 showing a plot illustrating a tangential velocity profile of exhaust gas at a turbine outlet for a third wastegate valve configuration;

[0133] Fig. 27 shows a plot illustrating the risk of deposit accumulation in a first embodiment of an exhaust system for a first wastegate valve configuration;

[0134] Fig.28 shows a plot illustrating the risk of deposit accumulation in a first embodiment of an exhaust system for a second wastegate valve configuration;

[0135] Fig.29 shows a plot illustrating the risk of deposit accumulation in a first embodiment of an exhaust system for a third wastegate valve configuration;

[0136] Fig.30 A drawing showing the risk of deposit accumulation in a second embodiment of the exhaust system for a first exhaust gas valve configuration;

[0137] Fig.31 A drawing showing the risk of deposit accumulation in a second embodiment of the exhaust system for a second exhaust gas valve configuration;

[0138] Fig.32 A drawing showing the risk of deposit accumulation in a second embodiment of the exhaust system for a third exhaust gas valve configuration;

[0139] Fig.33 A drawing showing the magnitude of wall shear stress in a third embodiment of the exhaust system for a first exhaust gas valve configuration;

[0140] Fig.34 A drawing showing the magnitude of wall shear stress in a third embodiment of the exhaust system for a second exhaust gas valve configuration;

[0141] Fig.35 A drawing showing the magnitude of wall shear stress in a third embodiment of the exhaust system for a third exhaust gas valve configuration;

[0142] Fig.36 A drawing showing the magnitude of wall shear stress in a first embodiment of the exhaust system for a first exhaust gas valve configuration;

[0143] Fig.37 A drawing showing the magnitude of wall shear stress in a first embodiment of the exhaust system for a second exhaust gas valve configuration;

[0144] Fig.38 A drawing showing the magnitude of wall shear stress in a first embodiment of the exhaust system for a third exhaust gas valve configuration;

[0145] Fig.39 A drawing showing the magnitude of wall shear stress in a second embodiment of the exhaust system for a first exhaust gas valve configuration;

[0146] Fig.40 A drawing showing the magnitude of wall shear stress in a second embodiment of the exhaust system for a second exhaust gas valve configuration;

[0147] Fig.41 A drawing showing the magnitude of wall shear stress in a second embodiment of the exhaust system for a third exhaust gas valve configuration;

[0148] Fig.42 A drawing showing the magnitude of wall shear stress in a third embodiment of the exhaust system for a first exhaust gas valve configuration;

[0149] Fig.43 showing a plot illustrating the magnitude of wall shear stress in a third embodiment of an exhaust system for a second wastegate valve configuration;

[0150] Fig.44 showing a plot illustrating the magnitude of wall shear stress in a third embodiment of an exhaust system for a third wastegate valve configuration;

[0151] Fig.45 showing a plot illustrating velocity magnitudes and streamlines of exhaust gas in a fourth embodiment of an exhaust system at a first engine operating point;

[0152] Fig.46 Show Fig.45 A magnified view of a first region of interest;

[0153] Fig.47 showing a plot illustrating velocity magnitude and streamlines of exhaust gas in a fifth embodiment of an exhaust system at a second engine operating point;

[0154] Fig.48 Show Fig.47 a magnified view of a second region of interest;

[0155] Fig.49 showing a plot illustrating velocity magnitude and streamlines of exhaust gas in a sixth embodiment of an exhaust system at a third engine operating point;

[0156] Fig.50 Show Fig.49 A magnified view of a third region of interest;

[0157] Fig.51 Shown schematically Figure 8 and Fig. 9 A flowchart of another embodiment of the method shown;

[0158] Fig.52 is a graph showing the swirl angle in the turbine outlet passage as a function of the inlet gap size of the variable geometry mechanism at different expansion ratios on the turbine;

[0159] Figure 53 to Figure 55 Shown in a wastegate valve closed configuration, Figures 2 to 6 Plot of turbine exhaust velocity magnitude and streamlines;

[0160] Figure 56 to Figure 58 Shown in a partially open wastegate valve configuration, Figures 2 to 6 Plot of turbine exhaust velocity magnitude and streamlines;

[0161] Figure 59 to Figure 61 Shown in a fully open wastegate valve configuration, Figures 2 to 6Plot of turbine exhaust velocity magnitude and streamlines;

[0162] Fig.62 shows a three-dimensional view of an exhaust system, with various planes indicated schematically;

[0163] Fig.63 is a graph showing the effect of the three different wastegate valve configurations on the Fig.54 A graph of the relative amount of post-treatment fluid decomposition at each plane indicated in;

[0164] Fig.64 is a graph showing the effect of the three different wastegate valve configurations on the Fig.54 a graph of the relative uniformity index (UI) of the exhaust mixture at each plane shown;

[0165] Fig.65 The figure shows the turbine outlet at three different swirl angles. Fig.54 a graph of the relative amount of post-treatment fluid decomposition at each plane shown;

[0166] Fig.66 Shown schematically Figure 8 and Fig. 9 A flowchart of another embodiment of the method shown;

[0167] Figure 70 to Figure 72 shows a plot of wall shear stress inside the turbine outlet for three different wastegate valve configurations;

[0168] Figure 73 to Figure 75 a plot showing wall shear stress in an exhaust system for a wastegate valve closed configuration;

[0169] Figure 76 to Figure 79 a plot showing wall shear stress in an exhaust system for a partially open wastegate valve configuration;

[0170] Figure 80 to Figure 82 a plot showing wall shear stress in an exhaust system for a wastegate valve fully open configuration; and

[0171] Fig.83 A schematic block diagram of a method according to another embodiment is shown. DETAILED DESCRIPTION

[0172] Figure 1 Schematic diagram of a known turbocharged diesel engine system 2. The system 2 includes a diesel internal combustion engine 4, a turbocharger 6 and an exhaust aftertreatment system 8.

[0173] The turbocharger 6 includes a compressor 10 and a turbine 12, each of which includes a corresponding one of a compressor impeller and a turbine impeller. The compressor impeller and the turbine impeller are mounted on a common turbocharger shaft 14 so that the compressor impeller and the turbine impeller rotate together.

[0174] The compressor 10 receives intake air from a low-pressure intake duct 16 connected to the atmosphere. The low-pressure intake duct 16 may include a particulate filter to clean the intake air. The compressor 10 compresses the intake air using the power provided by the turbine 12 (via the turbocharger shaft 14) and supplies the compressed intake air to the engine 4 through the high-pressure intake duct 18 and the intake manifold 20. Although not shown, the high-pressure intake duct 18 may include an intercooler configured to cool the intake air before the intake air reaches the engine 4.

[0175] Inside the engine 4, an internal combustion process takes place and produces useful work. As a result of the internal combustion process, the engine 4 produces exhaust gas. The engine 4 is fluidly connected to an exhaust manifold 22, which in turn is connected to the turbine 12 via a high-pressure exhaust pipe 24. The turbine 12 (particularly its turbine wheel) extracts energy from the exhaust gas to drive the turbocharger shaft 14 and thereby power the compressor 10. The exhaust gas leaving the turbocharger 12 is supplied to the exhaust aftertreatment system 8 via a downpipe 26. The length of the downpipe 26 is relatively long, for example at least 2 meters long, such as Figure 1 As shown by the dotted line in .

[0176] The exhaust aftertreatment system 8 includes a decomposition chamber 28 having a diameter greater than the diameter of the downcomer 26. The decomposition chamber 28 includes a mixing element 30 disposed therein. The mixing element 30 typically includes a plurality of baffles configured to deflect the flow through the decomposition chamber 28 to induce turbulence within the decomposition chamber 28. The exhaust aftertreatment system 8 includes a dosing module 32 configured to inject an exhaust aftertreatment fluid, particularly diesel exhaust fluid (DEF), into the decomposition chamber 28 downstream of the mixing element 30 in the most turbulent region of the exhaust gas. The heat exchange between the DEF and the exhaust gas in the decomposition chamber 28 decomposes the urea contained in the DEF into a reducing agent ammonia (NH 3 ) and isocyanate (HNCO). The mixture of the reductant and the exhaust gas is then delivered to the selective catalytic reducer (SCR) 34 and the diesel oxidation catalyst (DOC) 36. Finally, the exhaust gas is delivered to the outlet pipe 38 and further delivered to the muffler (not shown) before being discharged into the atmosphere.

[0177] Figure 21 is a perspective view of a turbocharger 100, generally viewed from above, including an exhaust system 105 (which may be referred to as a turbine distribution system) according to an embodiment of the present disclosure. The turbocharger 100 includes a turbine 101 and a compressor 103 interconnected by a bearing housing 106. Due to the incorporation of a wastegate (as will be described in detail later in this document), the turbocharger 100 may be described as a wastegate turbocharger, and the exhaust system may be described as a wastegate exhaust system.

[0178] In the illustrated embodiment, the turbine 101 forms part of the exhaust system 105. This is due to the incorporation of a dosing module 126. This will be described in detail later in this document.

[0179] The turbine 101, and more generally the exhaust system 105, includes a turbine housing assembly 102. The turbine housing assembly 102 includes a turbine housing 108 and a connection adapter 110. The turbine housing assembly 102 differs from, for example, a monolithic turbine housing in that (compared to the one-piece turbine housing structure of the monolithic turbine housing) the turbine housing 108 and the connection adapter 110 are multi-part assemblies. The turbine housing 108 is the portion of the turbine housing assembly 102 that is proximate to the bearing housing 106. The turbine housing 108 is configured to engage the bearing housing 106. The connection adapter 110 is spaced from the bearing housing 106 by at least the extent / length of the turbine housing 108. In other words, the connection adapter 110 is disposed downstream of the turbine housing 108.

[0180] In the illustrated embodiment, the turbine housing 108 defines a turbine inlet passage 112, a turbine wheel chamber ( Figure 2 In particular, the turbine housing 108 defines an upstream portion of the turbine outlet passage 116 (not visible in FIG. 1 ). Figure 2 The turbine inlet passage 112 is defined by a volute 113 (which may also be referred to as a scroll) and is configured to receive exhaust gas from an internal combustion engine (not shown). Thus, the volute 113 is a structure that defines the turbine inlet passage 112. The turbine inlet passage 112 forces the exhaust gas to rotate about the turbine wheel axis ( Figure 2 Not shown, but in Figure 4 In other words, the geometry of the turbine inlet passage 112 causes the exhaust gas flow to swirl around the turbine wheel ( Figure 2 Not visible in , but in Figure 4The turbine inlet passage 112 may also impart an axial component to the exhaust flow (e.g., in the case of a mixed-flow turbine wheel, but this is not the case in the illustrated embodiment). The turbine inlet passage 112 may be described as extending in at least a circumferential and radial direction of the turbine wheel axis. As the exhaust gas expands through the turbine wheel, the swirl of the exhaust gas changes and may even reverse depending on flow conditions and surrounding geometry.

[0181] The connection adapter 110 defines a downstream portion 116b of the turbine outlet passage 116. The downstream portion 116b may be referred to as a connection adapter passage. The first end 118 of the connection adapter 110 is engaged with the turbine housing 108 (via the insertion of a gasket 117). Thus, the downstream portion 116b of the turbine outlet passage 116 defined by the connection adapter 110 is coupled to the upstream portion 116a of the turbine outlet passage 116 (defined by the turbine housing 108, at Figure 2 Not visible in , but in Figure 4 It will be appreciated that the insert gasket 117 is an optional feature and may not be present in other embodiments.

[0182] In the illustrated embodiment (and from Figure 4 As can be understood in the connection adapter 110, the connection adapter 110 defines a diffuser (e.g., an expanded portion of the turbine outlet passage 116). Therefore, the exhaust gas expands when passing through the connection adapter 110. It can therefore be said that the connection adapter 110 defines a diffuser cone, an outlet diffuser, or a turbine stage outlet diffuser. In other words, the connection adapter 110 defines at least a portion of the diffuser of the turbine 102, and optionally defines the entire diffuser of the turbine 102.

[0183] Defining a portion of the turbine outlet passage 116 by the connection adapter 110 is advantageous because different connection adapters may be secured or attached to the same turbine housing 108 design. Different connection adapters may incorporate different features for different applications.

[0184] Return to Figure 2, the connection adapter 110 includes an inner surface 111. The connection adapter 110 further includes a dosing module mount 122 and a NOx sensor mount 124. The dosing module mount 122 engages with the dosing module 126. Accordingly, the dosing module mount 122 aligns with and supports the dosing module 126. The dosing module 126 is configured to deliver the aftertreatment fluid into the exhaust gas in the turbine outlet passage 116. The dosing module mount 122 and the dosing module 124 will be described in more detail hereinafter. The dosing module 126 is arranged in fluid communication with a tank or reservoir storing a certain amount (e.g., a certain volume) of the aftertreatment fluid.

[0185] The exhaust system 105 further includes an exhaust gas sensor, which is a NOx sensor 128 in this embodiment. The exhaust system 105 further includes a NOx sensor mount 124. The NOx sensor mount 124 is engaged by the NOx sensor 128.

[0186] Finally, Figure 2 An exhaust gas bypass outlet 138 is also shown. The exhaust gas bypass outlet 138 is a hole defined in the inner surface 111 (e.g., a wall) of the connection adapter 110. In use, (bypass) exhaust gas can be delivered around the turbine impeller, through the exhaust gas bypass passage 136 and into the turbine outlet passage 116 via the exhaust gas bypass outlet 138.

[0187] Returning to Figure 3 , an alternative perspective view of the turbocharger 100 is provided.

[0188] Figure 3 The turbocharger 100 is shown as a wastegate turbocharger, which includes a wastegate device 132. The wastegate device 132 forms part of the exhaust system 105. The wastegate device 132 includes a valve assembly ( Figure 3 not visible in the figure) and an exhaust gas bypass passage 136. As described above, the exhaust gas bypass passage 136 defines a fluid path directly from the turbine inlet passage 112 to the turbine outlet passage 116. In the illustrated embodiment, the exhaust gas bypass passage 136 is partially defined by the turbine housing 108 and partially defined by the connection adapter 110. For example, neither the turbine housing 108 nor the connection adapter 110 can define the entire exhaust gas bypass passage. The exhaust gas bypass passage 136 provides selective fluid communication between the turbine inlet passage 112 and the turbine outlet passage 116, thereby bypassing the turbine impeller chamber and the turbine impeller. In this way, the (bypass) exhaust gas in the turbine inlet passage 112 can flow through the exhaust gas bypass passage 136 to reach the turbine outlet passage 116 without passing through the turbine impeller 118 or expanding through the turbine impeller 118. This allows controlling the rotational speed of the turbine impeller.

[0189] The wastegate passage 136 includes a wastegate passage inlet and a wastegate passage outlet ( Figure 3 The wastegate passage inlet is defined by an opening in the wall of the turbine housing 108 that defines the turbine inlet passage. Thus, the exhaust gas flow enters the wastegate passage 136 via the wastegate passage opening and exits the wastegate passage 136 via the wastegate passage outlet ( Figure 3 As the (bypass) exhaust gas exits the wastegate passage 136 , it mixes with the (turbine main flow) exhaust gas in the turbine outlet passage 116 .

[0190] According to the terminology used throughout this document, the wastegate passage 136 refers to the volume through which the (bypass) exhaust gas flows. The wastegate passage 136 can be described as a wastegate passage (the wastegate passage is located at Figure 3 136). In the illustrated embodiment, the wastegate passage is defined by an upstream portion 133 and a downstream portion 135. The upstream portion 133 of the wastegate passage is defined by the turbine housing. The downstream portion 135 of the wastegate passage is defined by the connection adapter 110. Therefore, the connection adapter 110 can be described as including at least a portion of the wastegate passage and / or at least a portion of the wastegate passage 136. The combination of the upstream portion 133 and the downstream portion 135 can be the entire wastegate passage / the entire wastegate passage.

[0191] The bypass exhaust flowing through the wastegate passage outlet is a high energy exhaust flow that has not yet passed through the turbine impeller for expansion. Therefore, the area where the two high speed airflows (e.g., the turbine main flow and the bypass flow) converge is confined near the wastegate passage outlet. A high level of mixing can be achieved in this area, and the mixing level is affected by the momentum exchange of the two airflows. For reasons described in detail below, a high level of mixing is utilized by positioning the dosing module 126 near the wastegate passage outlet.

[0192] The wastegate assembly includes a valve member (an example of a bypass control valve) that can be rotated by an actuating rod 142. In use, the actuating rod 142 is configured to rotate the valve member so that the valve member contacts or does not contact a corresponding valve seat defined by the turbine housing 108. The valve member is used to selectively sealably engage the valve seat to selectively open and close the wastegate passage 136, thereby allowing or substantially preventing exhaust gas flow through the wastegate passage 136. When the valve member seals and engages the valve seat, the wastegate passage 136 is effectively closed, and all exhaust gas traveling through the turbine inlet passage is expanded through the turbine impeller. When the valve member is not sealably engaged with the valve seat, the wastegate passage 136 is at least partially open, and at least a portion of the exhaust gas traveling through the turbine inlet passage does not expand through the turbine impeller, but is conveyed around the turbine impeller via the wastegate passage 136. Therefore, the valve seat can be described as defining the inlet of the wastegate passage 136, and specifically defining the cross-sectional area of ​​the inlet of the wastegate passage 136.

[0193] The actuator rod 142 is a pneumatic actuator in the illustrated embodiment. In other embodiments, the actuator may be hydraulic or electric.

[0194] The turbine 101 is a wastegate turbine (as indicated by the actuation rod 142). However, in some embodiments described throughout this document, the turbine may not incorporate a wastegate assembly. The turbine may be a variable geometry turbine. Examples of variable geometry turbines include turbines that include a swinging vane assembly and / or an axially displaceable nozzle ring or other geometry that changes the degree of nozzle opening (upstream of the turbine wheel) through which the exhaust gas flows.

[0195] Figure 4 is a side cross-sectional view of the turbocharger 100 . Figure 4 Further features of the exhaust system 105 forming part of the turbocharger 100 are shown.

[0196] The connection adapter 110 includes a generally tapered inner surface 111 (e.g., a tapered wall) wherein the cross-sectional area of ​​the interior of the connection adapter 110 increases along the axial length of the connection adapter 110 from the first end 115 to the opposite second end 120. Thus, the cross-sectional area of ​​the turbine outlet passage 116 can be said to diverge along the connection adapter 110. The second end 120 is the end of the connection adapter 110 that is farthest from the turbine housing 108. The increasing cross-sectional area defines a diffuser. As the exhaust gas travels from the first end 118 to the second end 120 through the connection adapter 110, the velocity of the exhaust gas decreases and the static pressure of the exhaust gas increases due to the increase in the cross-sectional area of ​​the turbine outlet passage 116. Increasing the static pressure of the exhaust gas in the connection adapter 110 increases the efficiency of the turbine impeller 101 because the pressure recovery achieved by the connection adapter 110 allows a greater pressure ratio across the turbine impeller and, therefore, allows an increase in the efficiency of the turbine impeller.

[0197] like Figure 4 As shown, the turbine wheel chamber 114 houses a turbine wheel 118. The turbine wheel 118 is configured to rotate about a turbine wheel axis 144. The turbine inlet passage 112 is in fluid communication with the turbine wheel chamber 114. The turbine wheel chamber 114 is in fluid communication with the turbine outlet passage 116.

[0198] In use, the exhaust gas travels through the turbine inlet passage 112 and enters the turbine wheel chamber 114. The exhaust gas then expands across the turbine wheel 118 (i.e., performs work on the turbine wheel 118), which in turn drives the turbine wheel 118 to rotate about the turbine wheel axis 144. As the exhaust gas passes through the turbine wheel 118, the swirl size and / or swirl direction of the exhaust gas changes. The turbine wheel 118 is a radial turbine wheel, wherein the exhaust gas flow from the turbine inlet passage 112 strikes the turbine wheel 118 in a generally radial direction relative to the turbine wheel axis, and exits the turbine wheel 118 in a generally axial direction relative to the turbine wheel axis 144 (but with a swirl component). When the exhaust gas exits the turbine wheel 118 and leaves the wheel chamber 114, the exhaust gas enters the upstream portion 116a of the turbine outlet passage 116. In other embodiments, the turbine may be an axial turbine, where the exhaust gas enters the turbine wheel in a generally axial direction and exits the turbine wheel in a generally axial direction (but with a swirl component).

[0199] The turbine wheel 118 is supported by a shaft 146 for rotation about a turbine wheel axis 144. The shaft 146 extends from the turbine housing 108 through the bearing housing 106 to the compressor housing 104. The turbine wheel 118 is mounted at one end of the shaft 146, while the compressor wheel 148 is mounted at the other end of the shaft 146. The turbine wheel 118 may be mounted to the end of the shaft 146 by friction welding, laser welding, electron beam welding, or any other suitable method. Thus, the turbine wheel 118 and the compressor wheel 150 are in power communication with each other. The shaft 146 rotates about the turbine wheel axis 144 on a bearing assembly 150 located in the bearing housing 106.

[0200] In the illustrated embodiment, the turbine outlet passage 116 is defined by the turbine housing 108 and the connection adapter 110. The cross-sectional area of ​​the turbine outlet passage 116 increases linearly from the most upstream end of the passage (i.e., proximate the turbine wheel 118) to the most downstream end of the passage (i.e., away from the turbine wheel 118), thereby defining a diffuser.

[0201] The flow axis 145 is defined by the turbine outlet passage 116. The flow axis 145 is the (nominal) geometric centerline of the turbine outlet passage 116 defined by the turbine housing 108 and the connection adapter 110. In this embodiment, and as will be seen from Figure 5 As understood in , the flow axis 145 coincides with the turbine axis 144. However, in other embodiments where the turbine outlet passage 116 is not a straight passage, ie, the turbine outlet passage 116 may include a bend, the flow axis 145 will deviate from the turbine wheel axis 144.

[0202] The turbine impeller 118 is Figure 4 , and includes a plurality of turbine blades 119. The turbine wheel 118 includes an inlet guide 172 configured to receive an exhaust flow 152a from the turbine inlet passage 112. The exhaust gas 152a is received in a radial direction relative to the turbine wheel axis 144. The turbine wheel 118 also includes an outlet guide 174 configured to discharge the exhaust flow from the turbine wheel 118. The exhaust flow is discharged along the flow axis 145. The outlet guide 174 defines an outlet guide diameter 176. The outlet guide diameter 176 is the distance across the turbine wheel 118 in a plane normal or perpendicular to the turbine wheel axis 144 at the downstream end of the blades 119. The downstream end or end of the turbine wheel 118 is at Figure 4178. In some embodiments, the downstream end of the turbine impeller 118 can be defined by an impeller nut, and the downstream end of the turbine impeller is located in the plane of the impeller nut. As described later in this document, the outlet guide diameter 176 can be used as a measure to define the position of the dosing module 126 relative to the downstream end of the turbine impeller 118. In the illustrated embodiment, the outlet guide diameter 176 is approximately 60 mm (e.g., 58 mm, 59 mm, 61 mm, 62 mm, etc.). In other embodiments, the outlet guide diameter i can be between about 30 mm and about 200 mm.

[0203] The cross-sectional area of ​​the upstream portion 116a of the turbine outlet passage 116 increases from the downstream end 178 of the turbine impeller 118. The cross-sectional area increases linearly (i.e., the inner wall surface diverges at a constant angle). In other embodiments, the turbine outlet passage or a portion thereof may have a constant cross-sectional area. In further embodiments, the turbine outlet passage may have a constant cross-sectional area, and then the cross-sectional area increases after a specific point along the flow axis. For example, the upstream portion of the turbine outlet passage defined by the turbine housing may be constant, while the downstream portion of the turbine outlet passage defined by the connection adapter may have a linearly increasing cross-sectional area.

[0204] In the illustrated embodiment, the inner surface 111 of the connection adapter 110 diverges linearly along the flow axis 145. In other embodiments, the inner surface 111 may diverge in a nonlinear manner. The angle of divergence may vary depending on the design conditions of each turbocharger. The divergence may be defined by the angle 121 at which the inner wall surfaces 162a, 162b of the wall 162 of the connection adapter 110 are inclined relative to each other. Angle 121 may be described as a diffuser angle. In the illustrated embodiment, angle 121 is about 7.5°. Angle 121 is preferably between about 5° and about 20°. Angle 121 is preferably between about 6° and about 15°. Angle 121 is preferably between about 7° and about 10°. Wall 162 is an example of a structure that defines at least a portion of the turbine outlet passage 116. In other embodiments, the connection adapter 110 may define a constant cross-sectional area before linearly diverging along the flow axis 145.

[0205] Accordingly, the angle 121 defines the diffuser angle of the turbine outlet passage 116. In the illustrated embodiment, the diverging portion of the turbine outlet passage 116 extends continuously through the upstream portion 116a (defined, for example, by the turbine housing 102 and the connection adapter 110) and the downstream portion 116b of the turbine outlet passage 116. In other words, the turbine outlet passage 116 diverges at a constant angle from an upstream point of the turbine outlet passage 116 (at the downstream end 178 of the turbine impeller 118) to at least the second end 192 of the connection adapter 110. The diverging portion also extends further upstream of the downstream end 178 of the turbine impeller 118 and into the impeller chamber 114. Accordingly, a portion of the impeller chamber 114 diverges. In other embodiments, the diverging portion may be defined by the connection adapter 110 (e.g., not extending beyond the connection adapter 110).

[0206] As described previously, the connection adapter 110 includes a dosing module mount 122. In the illustrated embodiment, the dosing module mount 122 is integrally formed with the connection adapter 110. In other words, the dosing module mount 122 and the connection adapter 110 are a single structure. Accordingly, the dosing module mount 122 and the connection adapter 110 can be manufactured by casting a single combined structure. The dosing module mount 122 defines an opening 164 in the inner surface 111 of the connection adapter 110. The opening 164 can be described as a dosing orifice. The aftertreatment fluid is injected into the exhaust through the opening 164. For completeness, the dosing module mount 122 can be incorporated as part of the turbine housing (e.g., an integral turbine housing—a single-piece or monolithic turbine housing and diffuser), the connection adapter, or a conduit. That is, the dosing module 126 can be mounted to the turbine housing, the integral turbine housing, the connection adapter, or a conduit downstream of the turbine.

[0207] The dosing module 126 is a self-atomizing dosing module configured to inject the aftertreatment fluid as a fine spray from the outlet 166 of the dosing module 126. The dosing module 126 is configured to inject the aftertreatment fluid into the main exhaust stream 152b in the turbine outlet passage 116 downstream of the turbine impeller 118. Since the aftertreatment fluid is injected as a fine spray, there is no need to inject the aftertreatment fluid into a structure that promotes atomization of the aftertreatment fluid, such as a rotating dosing cup disposed in the turbine impeller, and then mix it with the main exhaust stream 152b. The dosing module 126 injects the aftertreatment fluid as a fine spray in a generally conical pattern from the outlet 166. The spray cone (of the atomized aftertreatment fluid) is labeled 139.

[0208] A primary impact zone is defined where the spray 139 encounters the inner surface 111. Due to the risk of corrosion from byproducts of the post-treatment fluid, it is desirable that at least the primary impact zone of the inner surface 111 has some corrosion resistance properties. For example, a sleeve made of a corrosion resistant material may be incorporated. In other embodiments, the connection adapter 110 may be made of a corrosion resistant material. Stainless steel is an example of a corrosion resistant material. The entire inner surface 111 may be covered with or made of a corrosion resistant material such as stainless steel. Other materials that are also corrosion resistant may be used in place of or in combination with stainless steel.

[0209] In the illustrated embodiment, the dosing module 126 is angled toward the flow axis 145 such that the dosing module 126 (specifically, the outlet 166 of the dosing module 126) points in a downstream direction (e.g., toward the second end 120 of the connection adapter 120, and away from the turbine wheel 118). Thus, the aftertreatment fluid discharged by the dosing module 126 is injected in a (slightly) with-flow direction. Given that the orientation of the dosing module 126 is defined by the dosing module mount 122, the dosing module mount 122 is also angled toward the flow axis 145 such that the opening 164 of the dosing module mount 122 points in a downstream direction. This orientation is desirable for reasons of more predictable spray placement over a wider range of engine operating conditions.

[0210] However, it should be understood that in other embodiments, the distribution module 126 and the distribution module mount 122 may be angled so that the after-treatment fluid is injected in a perpendicular direction (e.g., in a radial direction) relative to the flow axis 145. In further embodiments, the distribution module 126 and the distribution module mount 122 may be angled so that the after-treatment fluid is injected in an upstream direction (i.e., toward the turbine wheel 118).

[0211] The minimum distance 180 between the centroid of the outlet 166 of the dosing module 126 (and, due to the concentric alignment, also the centroid of the opening 164 of the dosing module mount 122) and the flow axis 145 defines an outlet intersection point 182 along the flow axis 145. The outlet intersection point 182 marks the axial position of the opening 164 and the outlet 166 along the flow axis 145.

[0212] Similarly, a minimum distance between the centroids 139 of the wastegate passage outlets 138 defines a wastegate passage intersection point 183 along the flow axis 145 . The wastegate passage intersection point 183 marks the axial position of the wastegate passage outlets 138 along the flow axis 145 .

[0213] An axial distance 185 between the outlet intersection point 182 and the wastegate passage intersection point 183 along the flow axis 145 defines the position of the dosing module 126 relative to the wastegate passage outlet 138 .

[0214] By positioning the dosing module 126 along the flow axis 145 within and / or around 3 times the turbine outlet channel diameter of the wastegate channel outlet 138, the position where the aftertreatment fluid is injected into the turbine outlet channel 116 is positioned relatively close to the wastegate channel outlet 138. Therefore, the aftertreatment fluid is injected into a relatively high-energy exhaust flow that has not yet expanded through the turbine impeller 118. The aftertreatment fluid is also injected into the region where two high-speed airflows (e.g., the turbine main flow 152b and the bypass flow 152c) converge. Therefore, a high level of mixing is achieved, and the mixing level is affected by the momentum exchange of the two airflows. By injecting the aftertreatment fluid near the wastegate channel outlet 138, the increased mixing level in the above-mentioned region contributes to the dispersion of the aftertreatment fluid (especially its reductant) in the entire exhaust flow. The aftertreatment fluid is also subjected to a high level of relative velocity (i.e., gas velocity to reductant droplet velocity), which increases convective heat transfer to the droplets, thereby increasing decomposition. As the droplet passes through the high mixing zone, it is exposed to many different local velocities that push, pull & shear the droplet in different directions. This chaotic flow field (which can be indicated by the turbulent kinetic energy (TKE) metric) promotes mixing. The bypass flow 152c is also relatively hotter than the main turbine flow 152b because the bypass flow 152c has not yet expanded through the turbine impeller 118. The higher exhaust temperature promotes the decomposition of the injected aftertreatment fluid by promoting the evaporation of the deionized water and the thermal decomposition of the urea into the constituent reductants.

[0215] Removal of harmful gases from the bulk exhaust flow 152b is thereby facilitated.

[0216] The distance between the downstream end 178 of the turbine impeller 118 and the intersection 182 is about 2.4 times the diameter of the outlet inducer measured along the flow axis 145 (i.e., about 2.4 times the distance indicated by the number 176). The intersection 182 is preferably located up to about 10 times the diameter of the outlet inducer downstream of the downstream end 178 of the turbine impeller 118 measured along the flow axis 145. The intersection 182 may be between about 3 times the diameter of the outlet inducer and about 7 times the diameter of the outlet inducer downstream of the downstream end 178 of the turbine impeller 118 measured along the flow axis 145. In other embodiments, the distance between the downstream end 178 of the turbine impeller 118 and the outlet intersection 182 may be different. However, the distance is preferably no more than about 10 times the diameter of the outlet inducer, and is preferably within about 5 times the diameter of the outlet inducer.

[0217] By positioning the dosing module 126 and the dosing module outlet 166 relatively close to the turbine wheel 118, the decomposition of the injected aftertreatment fluid into the reductant (e.g., ammonia (NH 3) and isocyanate (HNCO) to support the downstream SCR reaction). This is because the distance between the location where the aftertreatment fluid is injected and the downstream selective catalytic reduction (SCR) catalyst is increased, so the time available for decomposition before reaching the SCR catalyst is also increased, thereby increasing the amount of decomposition of the injected aftertreatment fluid. This is particularly beneficial when operating at relatively low exhaust temperatures, such as at engine start-up.

[0218] Decomposition is facilitated, at least in part, because after the main exhaust stream 152b is discharged from the turbine impeller 118, the swirl of the main exhaust stream 152b is greater than, for example, the exhaust gas significantly downstream of the turbine impeller (e.g., in the decomposition chamber). Therefore, there are regions of high turbulent kinetic energy within the exhaust stream (which facilitates mixing of the aftertreatment fluid with the main exhaust stream due to increased momentum exchange between the aftertreatment fluid and the main exhaust stream), and their amplitude is greater due to proximity to the turbine impeller 118. The higher turbulent kinetic energy of the main exhaust stream also facilitates droplet breakup of the injected aftertreatment fluid. Increasing droplet breakup of the aftertreatment fluid can improve the uniformity of mixing of the aftertreatment fluid with the main exhaust stream, thereby increasing decomposition of the aftertreatment fluid.

[0219] The temperature of the bulk exhaust stream 152b is also relatively high near the turbine wheel 118. The higher exhaust temperature promotes decomposition of the injected aftertreatment fluid by promoting evaporation of deionized water and thermal decomposition of urea into constituent reductants. Higher convective heat transfer from the bulk turbine stream to the aftertreatment fluid droplets also promotes decomposition.

[0220] The velocity of the bulk exhaust flow at the walls of the turbine outlet passage 116 is also higher near the turbine wheel 118 than at locations further downstream. The higher velocity creates relatively high shear forces in these regions and reduces the risk of aftertreatment fluid settling on, for example, the inner surfaces 111 defining the turbine outlet passage 116. Thus, the risk of undesirable deposit accumulation within the turbine outlet passage 116 is also reduced. The relatively high velocity of the bulk turbine flow also helps to improve convective heat transfer to the aftertreatment fluid droplets.

[0221] Removal of harmful gases from the bulk exhaust flow 152b (eg, detoxification of the exhaust) is thereby facilitated.

[0222] Placing the dosing module 126 near the downstream end 178 of the turbine wheel 118 can help address or otherwise mitigate: i) poor decomposition of the aftertreatment fluid due to low exhaust temperatures and / or low turbulent kinetic energy of the exhaust flow; ii) packaging considerations / packaging limitations when positioning the dosing module further downstream of the engine; iii) undesirable system backpressure due to use of a conventional downstream decomposition chamber, which can reduce upstream engine efficiency; iv) aftertreatment deposit formation on any near-interior surfaces; and v) high thermal mass of downstream aftertreatment components (e.g., decomposition chambers) of conventional systems.

[0223] In the illustrated embodiment, the dosing module 126 is positioned such that the outlet 166 overlaps the wastegate passage outlet 138 along the flow axis 145. Furthermore, in the illustrated embodiment, the centroid of the outlet 166 is located within the axial length 137 of the wastegate passage outlet 138. The outlet intersection point 182 (indicating the location of the outlet 166 of the dosing module 126) is therefore located within the axial length 137 of the wastegate passage outlet 138. In the illustrated embodiment, the centroid of the outlet 166 is also substantially axially aligned with the centroid 181 of the wastegate passage outlet 138. It should be understood that in other embodiments, the axial offset 185 between the dosing module 126 and the centroid of the wastegate passage outlet 138 can be greater and up to within about 3 turbine outlet passage diameters along the flow axis 145.

[0224] Throughout the above description, it should be understood that references to the location of the outlet 166 of the dispensing module 126 also apply to the opening 164 of the dispensing module mount 122. This is because the dispensing module 126 is concentrically mounted to the dispensing module mount 122. Due to the concentric alignment between the components, the outlet 166 and the opening 164 can be said to share a centroid.

[0225] Wastegate passage outlet 138 is circumferentially spaced from outlet 166 about flow axis 145. Figure 5 As shown, wastegate passage outlet 138 is circumferentially spaced about flow axis 145 from outlet 166 of dosing module 126 by about 90 degrees. In a preferred embodiment, wastegate passage outlet 138 is circumferentially spaced about flow axis 145 from outlet 166 of dosing module 126 by between about 30 degrees and about 110 degrees.

[0226] Return to Figure 4 , the wastegate passage 136 is aligned so that the wastegate passage exhaust flow 152c (i.e., the bypass flow) exits the wastegate passage outlet 138 and enters the turbine outlet passage 116 (particularly the downstream portion 116b thereof) at a velocity that is generally tangential to the flow axis 145. This is also Figure 5 Shown in.

[0227] Outlet 166 is shown overlapping axial length 137 of wastegate passage outlet 138. Because axial distance 185 is generally less than a major dimension (eg, diameter) of opening 164, outlet 166 is also substantially axially aligned with centroid 181 of wastegate passage outlet 138.

[0228] The elongated geometry of the wastegate passage outlet 138 in the direction of the flow axis 145 (e.g., the hole is letterboxed) and the tangential introduction of the wastegate passage exhaust flow generate relatively high shear forces in the wastegate passage exhaust flow. The shear forces are generated by a layer of relatively high velocity exhaust gas near the inner surface 111. Such shear forces are desirable because they improve mixing of the aftertreatment fluid with the exhaust gas and reduce the risk of deposits accumulating on the inner surface 111, particularly near the primary impact zone (e.g., the surface generally opposite the outlet 166 of the dosing module 126 and formed by the inner surface 111). Figure 4 The letterbox-shaped wastegate passage outlet 138 also means that shear forces are generated over a relatively large surface area (eg, along the flow axis 145).

[0229] The bulk flow 152b exiting the turbine wheel 118 will swirl in a positive angular direction about the centerline 145. The wastegate passage outlet 138 is configured such that the flow layer 153c enters the diffuser in a positive angular direction in a generally tangential direction to the centerline 145. According to the bulk flow 152b and the flow layer 152c, swirl in the same angular direction about the centerline 145. This enables the flow layer 152c to increase the angular component of the velocity of the bulk flow 152b so as to contribute to the total angular momentum of the combined flow.

[0230] although Figure 4 The outlet 166 of the dosing module 126 is shown substantially aligned with the inner surface 111, but in other embodiments, the outlet 166 (optionally, a nozzle of the dosing module 126 in which the outlet 166 is disposed) may protrude into the turbine outlet passage 116 (e.g., protrude beyond the opening 164). Substantially aligned (i.e., substantially flush) is intended to mean that the outlet 166 is within about ±2 mm of the opening 164 in the inner surface 111 along the dosing module axis 167. This reduces the risk of exhaust gas recirculation near the outlet 166 of the dosing module 126.

[0231] Figure 5 is an end view of the turbocharger 100 viewed from the end of the turbine housing assembly 102 .

[0232] In the illustrated embodiment, the angle 184 between the dosing module axis 167 and the central axis 186 of the NOx sensor 128 (i.e., the circumferential offset between the dosing module 126 and the NOx sensor 128) is approximately 90 degrees (about the flow axis 145). The angle 184 is preferably between about 30 degrees and about 90 degrees. Similarly, in the illustrated embodiment, the angle 187 between the wastegate passage outlet axis 189 passing through the centroid of the wastegate passage outlet 138 and the dosing module axis 167 (i.e., the circumferential offset between the centroid of the wastegate passage outlet 138 and the dosing module 126) is also approximately 90 degrees about the flow axis 145. The angle 187 is preferably between about 45 degrees and about 110 degrees. In the illustrated embodiment, the angle 188 between the wastegate passage outlet axis 189 and the central axis 302 of the NOx sensor 128 (i.e., the circumferential offset between the centroid of the wastegate passage outlet 138 and the NOx sensor 128) is approximately 180 degrees. The angle 188 is preferably between about 75 degrees and about 180 degrees. In the illustrated embodiment, the dosing module 126 is circumferentially located between the wastegate passage outlet 138 and the NOx sensor 128 .

[0233] Figure 5 Also shown is wastegate passage exhaust flow 152c entering turbine outlet passage 116 in a generally tangential direction. Figure 5 As shown, when viewed from the outer end of the connection adapter 110, the wastegate channel exhaust flow 152c swirls in a generally counterclockwise direction. The swirl direction is the same as the direction of the swirl of the main exhaust flow 152b when it expands through the turbine impeller 118. Therefore, the wastegate channel exhaust flow 152c can be considered to swirl in the same direction as the main exhaust flow 152b. The swirl direction can be described relative to the direction extending toward the impeller chamber around the turbine impeller axis (in the illustrated embodiment, coinciding with the flow axis 145) of the volute 113. Specifically, the exhaust flow swirls in the same direction as the direction in which the volute 113 extends. The swirl direction of the main exhaust flow 152b may vary with the engine operating conditions. For example, under certain operating conditions, the main exhaust flow or a portion of the main exhaust flow may swirl in a direction opposite to the direction in which the volute 113 extends. For example, under operating conditions where the turbine achieves peak power output, the main exhaust flow may swirl in a direction substantially the same as the direction in which the volute 113 extends. However, if the turbine is operated under lower load conditions, part or all of the main exhaust flow may swirl in a direction opposite to the direction in which the volute 113 extends. However, for the purposes of this document, the swirl direction of the turbine main exhaust flow is referred to as the nominal swirl direction. The nominal swirl direction is the same direction in which the volute 113 extends, and is the same direction in which the turbine impeller 118 rotates (or can rotate in use).

[0234] Figure 6is from Figure 4 1 is a cross-sectional end view of the turbocharger 100 taken along plane AA shown in FIG.

[0235] Figure 6 The NOx sensor 128 is shown axially upstream of the dosing module 126 (ie, closer to the turbine wheel 118 ). This is to reduce the risk of aftertreatment fluid impinging on the NOx sensor 128 .

[0236] Figure 6 It is shown how both the dosing module mount 122 and the NOx sensor mount 124 are integrated with the connection adapter 110. In other words, the dosing module mount 122 and the NOx sensor mount 124 form an integral structure with the connection adapter 110. In other embodiments, the dosing module mount 122 and / or the NOx sensor mount 124 may be formed of separate components that are subsequently connected to the connection adapter 110.

[0237] Figure 6 Also shown are a portion of wastegate passage 136 , valve member 140 , and further portions of the path taken by wastegate passage exhaust flow 152 c . In the illustrated embodiment, valve member 140 is mounted within the turbine housing, but may be mounted within connection adapter 110 in other embodiments.

[0238] Figure 7is a schematic block diagram of an exhaust system 200 according to an embodiment of the present disclosure. The exhaust system 200 is configured to receive exhaust gas from an internal combustion engine 202. The exhaust system 200 includes a turbine 204 having a turbine inlet 206, a turbine wheel 208, and a turbine outlet 210. The turbine inlet 206 receives exhaust gas from the internal combustion engine 202. The turbine wheel 208 is positioned in a turbine wheel chamber (not shown) and receives exhaust gas from the turbine inlet 206. The turbine outlet 210 receives exhaust gas from the turbine wheel 208. The turbine outlet 210 may be an axial turbine outlet having a constant cross-sectional area, or may include a diffuser having an increasing cross-sectional area and configured to expand the exhaust gas received from the turbine wheel 208. The turbine 204 also includes a bypass passage 212 configured to route exhaust gas from a location upstream of the turbine impeller 208 to a location downstream of the turbine impeller 212 without traveling through the turbine impeller 212. The bypass passage 212 includes a bypass control valve 214 configured to selectively allow, prevent or otherwise control or regulate the flow of exhaust gas through the bypass passage 212. In some embodiments, the bypass control valve 214 may be a wastegate valve and / or a rotary control valve. The turbine 204 also includes a variable geometry mechanism 216 configured to control the flow of exhaust gas from the turbine inlet 206 to the turbine impeller 208. The variable geometry mechanism 216 may be any suitable variable geometry mechanism, such as a so-called swinging blade mechanism or a so-called sliding nozzle mechanism. In alternative embodiments, the turbine 204 may include only one of the bypass passage 212 (including the control valve 214) and the variable geometry mechanism 216. For example, turbine 204 may be Figures 2 to 6 The same turbine as described above (but incorporating a variable geometry mechanism) may be used, or may be a different turbine that only includes a variable geometry mechanism 216. Although the exhaust system 200 described above includes a turbine 204 having both a bypass control valve 214 and a variable geometry mechanism 216, in other embodiments, the turbine may incorporate only one of the bypass control valve and the variable geometry mechanism.

[0239] The exhaust system 200 also includes an aftertreatment device 218, which is configured to receive exhaust gas from the turbine outlet 210. The aftertreatment device 218 can be, for example, a catalyst, such as a diesel oxidation catalyst (DOC) or a selective catalytic reduction (SCR) catalyst. The exhaust system 200 also includes a dosing module 220, which is configured to deliver an aftertreatment fluid to the turbine outlet channel 210. In the case where the aftertreatment device is a DOC, the aftertreatment fluid can be, in particular, a hydrocarbon such as gasoline or diesel, and in the case where the aftertreatment device 218 is an SCR catalyst, the aftertreatment fluid can be, in particular, a mixture of ammonia and water, for example in a ratio of 67.5% by volume of water to 32.5% by volume of urea (sometimes referred to as diesel exhaust fluid (DEF) and sold under the registered trademark AdBlue). As combined Figures 2 to 5 As described, dosing module 220 may be mounted to the turbine housing (which may be a one-piece so-called "monolithic" turbine housing), to a connection adapter of the turbine, or, in some embodiments, to a duct downstream of the turbine.

[0240] The exhaust system 200 additionally includes a plurality of sensors configured to measure one or more physical characteristics of the exhaust gas. In particular, the exhaust system 200 includes a turbine inlet sensor 222, a turbine outlet sensor 224, an aftertreatment device outlet sensor 226, and an engine sensor 227. The turbine inlet sensor 222 may be configured to sense one or more of the following: the pressure of the exhaust gas in the turbine inlet, the temperature of the exhaust gas in the turbine inlet, the mass flow of the exhaust gas in the turbine inlet, or the volume flow of the exhaust gas in the turbine inlet. The turbine outlet sensor 224 may be configured to sense one or more of the following: the pressure of the exhaust gas in the turbine outlet, the temperature of the exhaust gas in the turbine outlet, the mass flow of the exhaust gas in the turbine outlet, the volume flow of the exhaust gas in the turbine outlet, or the NOx concentration of the exhaust gas in the turbine outlet. The aftertreatment device outlet sensor 226 may be configured to sense one or more of the following: the pressure of the exhaust gas at the outlet of the aftertreatment device, the temperature of the exhaust gas at the outlet of the aftertreatment device, the mass flow of the exhaust gas at the outlet of the aftertreatment device, the volume flow of the exhaust gas at the outlet of the aftertreatment device, or the NOx concentration of the exhaust gas at the outlet of the aftertreatment device. The engine sensors 227 may be configured to sense one or more of: engine speed, engine mass air flow, engine inlet pressure, engine inlet temperature, engine boost pressure, engine load, engine cylinder temperature, engine cylinder pressure, and engine fuel pressure.

[0241] Nevertheless, it should be understood that the above-mentioned sensors 222, 224, 226, 227 can be configured to sense other characteristics of the exhaust system 200 and / or the internal combustion engine 202, including but not limited to, for example: turbine inlet pressure; turbine inlet temperature, turbine outlet pressure, turbine outlet temperature, engine speed, throttle position, engine air mass flow, engine inlet pressure, engine inlet temperature, NOx concentration, catalyst gas temperature, engine fuel flow, engine air flow, engine boost pressure, engine intake pressure, engine load, engine rotation rate, engine cylinder temperature, engine cylinder pressure or engine fuel pressure. In addition, the exhaust system 200 may include a greater or lesser number of sensors suitable for the purpose of obtaining the information listed above and positioned at any relevant location within the system. For example, exhaust system 200 may include additional sensors (e.g., temperature sensors) at the inlet of aftertreatment device 218 (e.g., between turbine outlet sensor 224 and aftertreatment device 218 ) to measure aftertreatment device inlet temperature and / or pressure, and / or within aftertreatment device 218 to measure temperature and / or pressure of exhaust gas traveling through aftertreatment device 218 .

[0242] The exhaust system 200 includes a controller 228 that communicates with the sensors 222, 224, 226, 227 to receive information from the sensors. The controller 228 is also in communication with the bypass control valve 214 and the variable geometry mechanism 216. As will be described in detail below, the controller 228 is operable to receive and process information acquired by the sensors and to issue commands to the bypass control valve 214 and / or the variable geometry mechanism 216. The operating properties of the bypass control valve 214 and the variable geometry mechanism 216 can be adjusted in response to the commands issued by the controller 228. For example, the bypass control valve 214 can be moved by an actuator (not shown) in response to the commands issued by the controller 228 to control the flow of exhaust gas through the bypass passage 212. Similarly, the variable geometry mechanism can be moved by an actuator in response to the commands issued by the controller 228 to control the flow of exhaust gas through the turbine inlet 206 to the turbine impeller 208.

[0243] Figure 8A schematic block diagram of a method 300 for operating the exhaust system 200 described above is shown. The method may be implemented in use as a computing program stored in the controller 228. In a first step 302, the method includes determining a current characteristic of the exhaust. The current characteristic of the exhaust may be determined based on information received, for example, from sensors 222, 224, 226, 227. The current characteristic may be a quantity (e.g., temperature, pressure, etc.) that may be directly measured by a sensor at a specific location of the exhaust system 200. In other embodiments, the current characteristic may be a characteristic of the exhaust that cannot be directly measured by the sensor but is inferred by the controller 228 based on information received from the sensor related to other characteristics of the exhaust system 200. In particular, the controller 228 may include one or more formulas or data sets (e.g., a lookup table) that allow the controller 228 to infer the characteristics of the exhaust based on one or more inputs from the sensor. For example, the amount of swirl momentum of the exhaust gas in the turbine outlet 210 may be inferred based on knowledge of the current operating efficiency of the turbine 204, which in turn may be inferred based on parameters such as pressure and temperature at the turbine inlet and turbine outlet, engine mass flow, and engine speed. In general, it will be appreciated that the current characteristic of the exhaust gas may be any quantifiable characteristic, and further may include not only a single quantity of a characteristic at a particular spatial location, but may alternatively include an array of quantities of a characteristic across a range of spatial locations. For example, the current characteristic may be a temperature or velocity profile at a particular location or range of locations within the turbine outlet 210.

[0244] In a second step 304, the method 300 includes determining the presence (or absence) of a difference between the current characteristic of the exhaust gas determined in step 302 and the reference characteristic of the exhaust gas. As in the case of the current characteristic of the exhaust gas, the reference characteristic of the exhaust gas may be any quantifiable characteristic of the exhaust gas, and may further include a single quantity of the characteristic at a specific spatial location or an array of quantities of the characteristic across a range of spatial locations. The reference characteristic of the exhaust gas may be stored in a memory associated with the controller 228, for example as part of a data set. The controller compares the current characteristic with the reference characteristic to determine whether there is any difference between the two. In some arrangements, the level of the difference between the two may be quantified. In other arrangements, only the presence of a difference is identified. For example, the current characteristic may be the magnitude of the swirl momentum of the exhaust gas in the turbine outlet passage 210. The reference characteristic may be the magnitude of the swirl momentum in the turbine outlet passage 210 required to provide optimal mixing of the exhaust gas with the aftertreatment fluid. When the controller 228 determines that (for example) there is a difference between a current amount of swirl momentum in the turbine outlet 210 and a reference amount of swirl momentum in the turbine outlet 210, this indicates that the amount of swirl momentum of the exhaust gas in the turbine outlet 210 does not correspond to (for example) the amount of swirl momentum required for optimal mixing.

[0245] In a third step 306, the method 300 includes adjusting the variable geometry mechanism 216 and / or the bypass control valve 214 in response to determining that there is a difference in step 204. Adjusting the variable geometry mechanism 216 and / or the bypass control valve 214 will affect the characteristics of the exhaust gas in the turbine outlet 210. Accordingly, the variable geometry mechanism 216 and / or the bypass control valve 214 may be adjusted by the controller 228 to affect the characteristics of the exhaust gas in the turbine outlet 210 in a manner that addresses the nature of the difference between the current characteristics and the reference characteristics. In particular, following the swirl example discussed above, when the controller 228 determines that there is a difference between the current amount of swirl momentum in the turbine outlet 210 and the reference amount of swirl momentum in the turbine outlet 210 (and therefore, determines that the amount of swirl momentum of the exhaust gas in the turbine outlet 210 does not correspond to the amount of swirl momentum required for optimal mixing), the controller 228 outputs a control command to the variable geometry mechanism 216 and / or the bypass control valve 214 to move either or both mechanisms to a position that will optimize the amount of swirl momentum in the turbine outlet 210. This may include increasing or decreasing the amount of swirl, and / or changing the swirl direction of the flow at a larger point or a specific point in the flow. The configuration of the variable geometry mechanism 216 and / or the bypass control valve 214 that provides the optimal swirl may be determined by computer simulation and testing during the design and development of the exhaust system 200 and may be stored in a memory associated with the controller 228.

[0246] For example, during some operating conditions, the flow in the turbine outlet 210 exhibits angular velocities in two or more layers of opposite angular velocities in a generally annular ring about the axis of the turbine. In response to this difference, the variable geometry mechanism can be placed in a configuration where the magnitude between the velocities in opposite angular directions increases, and by doing so, thereby increasing the amount of turbulent mixing that occurs within the turbine outlet 201, thereby promoting better dispersion of the aftertreatment fluid and better heat transfer with the aftertreatment fluid. In such cases, the current characteristic of the turbine can be a velocity profile at the turbine outlet, and the difference can indicate the magnitude of the velocities in opposite angular directions in the turbine outlet.

[0247] It may be preferred that the turbine operates at an expansion ratio (which may be referred to as an optimal expansion ratio) that provides maximum turbine efficiency. The optimal expansion ratio will be a characteristic of the physical geometry of the turbine itself. At the optimal expansion ratio, the swirl angle of the exhaust gas in the turbine outlet will be zero. Therefore, the variable geometry mechanism 216 and / or the bypass control valve 214 may be controlled to increase or decrease the swirl in order to achieve the optimal expansion ratio. For example, during use, one or more reference characteristics of the exhaust gas may be used to determine the current expansion ratio. In particular, a suitable reference characteristic may be the turbine inlet pressure and / or the turbine outlet pressure (but it may be assumed that the turbine outlet pressure is atmospheric). Once the current expansion ratio is calculated, a lookup table may be used to determine the current swirl angle of the exhaust gas in the turbine outlet. The lookup value will be a characteristic of the turbine geometry. Based on the current swirl angle, the variable geometry mechanism 216 and / or the bypass control valve 214 may be controlled to increase or decrease the swirl in order to bring the swirl angle close to zero and thereby achieve the optimal expansion ratio of the turbine.

[0248] If it is determined that the temperature of the exhaust gas needs to be increased, this can be achieved by widening (opening) the variable geometry mechanism 216. This will reduce the work extracted from the exhaust gas by the turbine wheel 208 and thereby increase the exhaust gas temperature. Likewise, if it is determined that the temperature of the exhaust gas needs to be reduced, this can be achieved by narrowing (closing) the variable geometry mechanism 216 for corresponding reasons.

[0249] If it is determined that the wall shear stress applied by the exhaust gas to the turbine outlet passage 210 should be increased, this can be achieved by widening (opening) the variable geometry mechanism 216. This will reduce the flow restriction within the variable geometry mechanism and thereby allow a greater volume flow rate. Since shear stress is proportional to velocity, by increasing the volume flow rate, the wall shear stress can be increased. Likewise, it is determined that the wall shear stress should be reduced, which can be achieved by narrowing (closing) the variable geometry mechanism 216 for corresponding reasons.

[0250] It should be appreciated that in addition to operating conditions that require increased swirl, there may be operating conditions of the exhaust system 200 that may determine that reduced swirl is required. For example, excessive swirl may cause a wake zone to form in sensitive areas, such as near the end of the dosing module 220 or the NOx sensor 128.

[0251] It should be understood that adjustments to the variable geometry mechanism 216 and / or the bypass control valve 214 will result in changes in the expansion ratio across the turbine wheel 208. Changing the expansion ratio across the turbine wheel 208 will result in changes in the turbine wheel outlet dynamics, particularly including changes in the axial and angular components of the velocity of the exhaust gas. By accurately modeling the behavior of the outlet dynamics and storing them in the controller 228 in the form of one or more formulas or data sets, the variable geometry mechanism 216 and / or the bypass control valve 214 can be actuated to one or more configurations corresponding to the desired turbine wheel outlet flow dynamics, and thereby enhance or mitigate the occurrence of one or more specific effects in the exhaust system.

[0252] In view of the above, it can be seen that the exhaust system 200 and method 300 of the present disclosure are operable to provide control of flow properties downstream of the turbine impeller 208 using only the variable geometry mechanism 216 and / or the bypass control valve 214. In particular, the exhaust system 200 and method 300 do not require the use of any additional components beyond those already provided as part of the turbine 204, and in particular, avoid the use of additional baffles, fuel injectors, throttle valves, etc. Therefore, the exhaust system 200 and method 300 represent a more compact, economical, and flexible way to influence the exhaust flow to achieve one or more desired flow properties to improve the performance of the aftertreatment device 218.

[0253] Fig. 9 Another embodiment of the method 300 is shown. In a first step 302 and a second step 304, a current characteristic of the exhaust gas and a reference characteristic of the exhaust gas are determined, as described above. In a third step 306, a difference between the current characteristic and the reference characteristic is determined. Determining the difference between the current characteristic and the reference characteristic includes quantifying the difference between the current characteristic and the reference characteristic. Quantifying the difference may include, for example, arriving at a scalar value representing a magnitude difference between the current characteristic and the reference characteristic. Fig. 9 The method 300 includes an additional step 307, wherein the amount of the difference is compared to an acceptable range or threshold. If the amount of the difference is within the acceptable range, the method returns to step 302 via decision branch 310. However, if the amount of the difference falls outside the acceptable range, the method proceeds via branch 312 to step 308, where the variable geometry mechanism 216 and / or the bypass control valve 214 are adjusted.

[0254] Go to Fig.10 , a flow chart schematically indicating a method 400 according to another embodiment of the present disclosure is provided. In this embodiment, the determined characteristic of the exhaust gas is a temperature profile of the exhaust gas (ie, a current temperature profile).

[0255] At a first step 402, a current temperature profile of the exhaust is determined. The current temperature profile may be determined by directly measuring the temperature of the exhaust at one or more locations (e.g., by using a temperature sensor, such as a thermocouple). In other embodiments, the current temperature profile may be determined based on a measurement of another characteristic, processing the measurement, and inferring the temperature profile of the exhaust from the processing. For example, the current temperature profile of the exhaust may be determined and / or inferred based on one or more of the following: a current NOx reduction across one or more catalytic converters, an inlet exhaust temperature of an aftertreatment device (e.g., a catalytic converter), an outlet exhaust temperature of the aftertreatment device, an exhaust temperature within the aftertreatment device, an engine speed, an engine load / throttle position, an inlet manifold temperature, and an excess energy ratio (EER). The EER may be defined by the following equation:

[0256]

[0257] in:

[0258] is the mass flow rate of exhaust gas;

[0259] C p，air is the specific heat capacity of air;

[0260] T exhaust is the temperature of the exhaust gas at the turbine outlet;

[0261] is the mass flow rate of aftertreatment fluid (DEF) delivered by the dosing module to the turbine outlet;

[0262] C p，water is the specific heat capacity of water; and

[0263] h fg，water is the specific enthalpy of water vaporization.

[0264] As described above, any of the above quantities (eg, NOx reduction, inlet exhaust temperature, etc.) may be measured and one or more of the measured quantities processed in a computational operation to infer the current temperature profile of the exhaust gas.

[0265] The current temperature profile may be a single temperature at a single spatial location (e.g., at a location along the flow axis in a turbine outlet passage). The current temperature profile may include multiple temperatures (e.g., a distribution of) across a single spatial location (e.g., a temperature profile taken normal to the flow axis). The current temperature profile may include an average of multiple different temperatures at a single spatial location. In other embodiments, the current temperature profile may include any of the above options taken across multiple spatial locations. For example, the current temperature profile may include a 3D distribution of temperatures along a range of the flow axis. Spatial locations of particular interest may include the location of a distribution module and, if different, a primary impact zone defined by the distribution module. The turbine outlet is another spatial location that may be of particular interest.

[0266] Transitioning to step 404, a reference temperature profile for the exhaust is determined. It should be appreciated that the reference temperature profile preferably corresponds to the current temperature profile in terms of the type of temperature profile used (e.g., a single temperature at a single spatial location, multiple temperatures across a single spatial location, etc., as described above).

[0267] Go to step 406 and determine the difference between the current temperature profile and the reference temperature profile. In the case where the temperature profile is a single temperature at a single spatial location, the difference can be a subtraction equation. In the case where the temperature profile includes multiple temperatures, the difference can be calculated based on a statistical comparison. The difference can be based on an area average comparison. For example, the comparison can be an area weighted comparison of the exhaust temperature at the core of the flow and at the periphery of the flow (e.g., near a wall). Therefore, the comparison preferably takes into account spatial variations (e.g., whether the temperature is obtained at the core of the flow or at the periphery of the flow).

[0268] At step 408, the difference determined in step 406 is analyzed to determine whether the difference falls outside an acceptable range. An acceptable range can be, for example, a deviation from a preferred operating curve (e.g., within 10%, within 20%, or within 30% of the optimal operating curve). An acceptable range can be based on the possibility that the reductant in the aftertreatment fluid is not fully decomposed and / or excessive deposits accumulate in the exhaust flow. An acceptable range can be based on the allowable level of NOx reduction or reduction caused by one or more catalytic converters. An acceptable range can be based on the expected level of soot in the system. An example of an acceptable range is that the temperature at the periphery of the flow (e.g., near the wall) is at least about 550°K (280°C). Therefore, an acceptable range can incorporate a lower limit (i.e., minimum) temperature.

[0269] If the calculated difference at step 408 does not fall outside of the acceptable range, the method returns to step 402, as indicated by line 410. There may be a delay before the method 400 restarts at step 402. In other embodiments, the method 400 may continue to cycle repeatedly without any delay. The method is preferably performed periodically. The method may be performed in a dynamic periodic manner. For example, a minimum target usage interval, such as 100 hours, may be set before a regeneration event. In other words, a regeneration event may be performed only after 100 hours of use.

[0270] The difference calculated at step 408 falling outside of the acceptable range may indicate at least one of: an undesirably low breakup rate of after-treatment fluid droplets in the exhaust flow, and / or an undesirably high risk of deposit accumulation.

[0271] In response to the difference calculated at step 408 falling outside the acceptable range, as indicated by line 412, the method moves to step 414. At step 414, the variable geometry mechanism and / or the bypass control valve are adjusted. Based on the difference falling outside the acceptable range, as calculated at step 408, the variable geometry mechanism and / or the bypass control valve can be adjusted to increase the area that is centrally heated by the exhaust flow. The area of ​​central heating can be the core of the exhaust flow (e.g., to help reduce or reduce NOx and reduce aftertreatment device warm-up time). The area of ​​central heating can be near the periphery of the wall / flow (to increase the temperature of the wall, thereby reducing the risk of wall film and the associated risk of deposit accumulation). For the sake of completeness, it should be understood that increasing the temperature of the core of the exhaust flow can also achieve a heating effect near the conduit wall. Similarly, increasing the temperature of the exhaust gas near the wall can also provide a corresponding increased temperature at the core of the exhaust flow. However, method 400 proposes to prioritize one of these two options based on the current temperature profile. It may also be desirable to avoid heat build-up at the periphery of the flow due to heat being lost to the atmosphere via the walls (and thus reducing the decomposition rate of the reductant in the exhaust flow).

[0272] The core of the exhaust flow may refer to the radial cross-section of the flow extending up to about 30%, up to about 50%, or up to about 70% of the radial length from the flow axis. The exhaust flow near the wall may refer to the outermost up to 5%, 10%, or 25% of the radial cross-section of the exhaust flow. The boundary layer of the exhaust may correspond to the exhaust flow near the wall. The fully formed flow outside the boundary layer (e.g., beyond the boundary layer) may correspond to the core exhaust flow.

[0273] Steering Figures 11 to 13 , provides plots showing the results of computational fluid dynamics (CFD) simulations. Figures 11 to 13 Each figure shows the Figures 2 to 6 The turbine shown and Figure 7 Temperature profiles at the plane of the turbine wheel nut (e.g., at an axial position between the outlet inducer and the outermost end of the nut (e.g., at an axial position midway along the nut)) for three different configurations of wastegate valve positions (a wastegate valve is an example of a bypass control valve) for the exhaust system are shown. For completeness, the engine operating point (e.g., engine load and RPM / torque) was the same for each simulation.

[0274] Fig.11 shows a temperature curve when the wastegate valve is closed; Fig.12 shows a temperature profile when the wastegate valve is 50% open; and Fig.13 The temperature curve is shown when the wastegate valve is 100% open. Figures 11 to 13 It will be appreciated that the position of the wastegate valve (eg, wastegate valve configuration) can be appreciated to have an effect on the temperature profile of the exhaust gas. Figures 11 to 13 , it will be appreciated that the greater the degree to which the wastegate valve is opened, the greater the temperature across the temperature profile of the exhaust gas will generally be. This is due at least in part to the fact that the (bypass / wastegate) exhaust gas has not yet passed through the turbine wheel for expansion, and therefore has a relatively higher energy than exhaust gas that has passed through the turbine wheel for expansion. Furthermore, increasing the degree to which the wastegate valve is opened will generally increase the exhaust gas temperature at the core of the flow. In particular, for a substantially tangential wastegate passage (see Figure 6 For arrangements with wastegate passages 136 in the exhaust, opening the wastegate concentrates the heating at the periphery of the flow (e.g., near the walls). This in turn increases the wall temperature of surrounding components (e.g., turbine). For arrangements with non-tangential wastegate passages, opening the wastegate concentrates the heating at the core of the flow. This can be used to increase the temperature of downstream components (e.g., aftertreatment devices). The variable geometry mechanism can be adjusted (e.g., opened) to increase the exhaust temperature at both the periphery and the core of the flow. For completeness, Fig.11 The feature labeled 420 in the figure represents a region of the computational domain of the turbine impeller hub downstream of the turbine impeller blades where there may be a nut for securing the turbine impeller to the shaft (or a generally nut-shaped profile integral with the turbine impeller to aid in assembly of the integrated turbine and shaft assembly with the compressor). The temperature profile in this region is not predicted by the fluid dynamics calculations and therefore represents the fluid / solid boundary of the computational domain rather than a region of very high temperature.

[0275] Although described in the context of the wastegate valve open position Figures 11 to 13, but for a fixed geometry turbine, it will be appreciated that a similar effect can be obtained by varying the variable geometry mechanism of a fixed geometry turbine. For a variable geometry mechanism, opening the mechanism reduces the work done / extracted by the turbine and will generally increase the exhaust temperature. This effect is compounded if the exhaust is bypassed by a bypass valve (e.g. a wastegate valve). It will also be appreciated that a similar effect can be obtained by varying the wastegate valve opening position of a variable geometry turbine. Thus, Figures 11 to 13 Indicating that in response to step 408 identifying a particular operational risk, selective changes in the wastegate valve position may be used to increase the temperature in or at the concentrated heating area to reduce the risk. Specifically, adjusting the variable geometry mechanism and / or the bypass control valve may be used to change the temperature profile of the exhaust gas in the exhaust system. It should also be noted that while Figures 11 to 13 Results are shown for an exhaust system including a wastegate valve, but other types of bypass control valves may be used in other ways to achieve similar results.

[0276] Now turn to Figures 14 to 16 , three additional temperature curves are provided. Figures 14 to 16 The turbine (eg, Figures 2 to 6 Turbine or Figure 7 Temperature curve at the outlet of the exhaust system. Fig.14 A temperature profile showing a wastegate valve in a 100% closed configuration; Fig.15 showing a temperature profile with the wastegate valve in a 50% open configuration; and Fig.16 The temperature curve for the wastegate valve in a 100% open configuration is shown. Figures 14 to 16 As will be appreciated, increasing the degree to which the wastegate valve is opened generally increases the temperature of the exhaust gas passing through the turbine outlet passage. Fig.15 and Fig.16 It is understood that the temperature increase is particularly pronounced near the walls / at the periphery of the flow (see, e.g., notes 430 and 432). For completeness, Figures 14 to 16 The temperature curve shown is obtained at the location corresponding to Figure 4 The second end 192 of the connection adapter 110 is shown. This can be more generally described as the outlet of the turbine.

[0277] Steering Figures 17 to 19 , provides three plots showing the diffuser (e.g., Figures 2 to 6 Temperature profile at the wall of the diverging portion of the turbine outlet passage of the illustrated embodiment. Fig.17 The temperature profile is shown when the wastegate valve is in a 100% closed configuration. Fig.18is when the wastegate valve is in a 50% open configuration, and Fig.19 is when the wastegate valve is in a 100% open configuration.

[0278] By comparison Figures 17 to 19 It will be appreciated and as mentioned above, generally, opening the wastegate valve to any extent and diverting the exhaust gas around the turbine wheel will increase the temperature downstream of the turbine wheel. In particular, Fig.18 and Fig.19 Two regions 434, 436 of very high temperature are shown. Fig.17 does not exist in .

[0279] Figures 17 to 19 It is shown that manipulation of the wastegate valve can be used to change the temperature profile at the turbine outlet. Fig.18 and Fig.19 For example, if it is the case that the regions 434, 436 are identified as being susceptible to the risk of deposit accumulation, then by opening the wastegate to Fig.18 and Fig.19 In either the 50% open configuration shown or the 100% open configuration, any wall film (an indicator of deposit buildup) may be burned off before deposits develop.

[0280] In conjunction with the above description related to temperature profiles, it should be appreciated that the temperature profile (which may be a turbine outlet temperature profile) may need to be balanced or managed with engine demand at a given operating point.

[0281] Thus, adjusting the variable geometry mechanism and / or the bypass control valve may be used to change the temperature profile of the exhaust gas in the exhaust system. The adjustment may seek to increase the temperature of the exhaust gas at the core of the flow, or to increase the temperature of the exhaust gas at the periphery of the flow. The adjustment may seek to increase the temperature of the exhaust gas at the location of the distribution module or at another location downstream of the distribution module. Depending on the operating parameters in question, the locations may constitute areas of concentrated heating.

[0282] Go to Fig. 20 , a flow chart schematically indicating a method 500 according to another embodiment of the present disclosure is provided. In this embodiment, the determined characteristic of the exhaust gas is a velocity profile of the exhaust gas (i.e., a current velocity profile). For the sake of completeness and as will be described in detail below, it should be understood that the velocity profile can be used to determine or at least partially determine the velocity, swirl, and shear stress applied by the exhaust gas flow.

[0283] At a first step 502, a current velocity profile of the exhaust gas is determined. The current velocity profile may be determined based on a measurement of another characteristic, processing the measurement, and inferring a velocity profile of the exhaust gas from the processing. For example, the current velocity profile of the exhaust gas may be determined based on one or more of: a pressure ratio across the turbine, a turbine inlet pressure, a turbine outlet pressure, a turbine inlet temperature, a turbine rotation rate, and an engine mass flow rate.

[0284] The current velocity profile may be a velocity at a single spatial location (e.g., at a location along the flow axis in a turbine outlet passage). The current velocity profile may include multiple velocities (e.g., a distribution of velocities) across a single spatial location (e.g., a velocity profile taken normal to the flow axis). The current velocity profile may include an average at a single spatial location. In other embodiments, the current velocity profile may include any of the above options taken across multiple spatial locations. For example, the current velocity profile may include a 3D distribution of velocities along the length of the flow axis. Spatial locations of particular interest may include the location of a distribution module and, if different, the primary impact zone defined by the distribution module.

[0285] Transitioning to step 504, a reference velocity profile for the exhaust is determined. It should be appreciated that the reference velocity profile preferably corresponds to the current velocity profile in terms of the type of velocity profile used (e.g., velocity at a single spatial location, velocity distribution across a single spatial location, etc., as described above).

[0286] Going to step 506, the difference between the current speed profile and the reference speed profile is determined. In the case where the speed profile is the speed at a single spatial location, the difference can be a subtraction equation. In the case where the speed profile includes a speed distribution, the difference can be calculated based on a statistical comparison. For example, the comparison can be an area-weighted comparison of the speed distribution. Therefore, the comparison preferably takes into account spatial variations (e.g., the location where the speed is obtained).

[0287] At step 508, the difference determined in step 506 is analyzed to determine whether the difference falls outside an acceptable range. An acceptable range can be, for example, a deviation from a preferred operating curve (e.g., within 10%, within 20%, or within 30% of the optimal operating curve). The acceptable range can be based on the likelihood of excessive deposit accumulation.

[0288] If the calculated difference at step 508 does not fall outside of the acceptable range, the method returns to step 502, as indicated by line 510. There may be a delay before the method 500 restarts at step 502. In other embodiments, the method 500 may continue to cycle repeatedly without any delay. The method is preferably performed periodically. The method may be performed in a dynamic periodic manner. For example, a minimum target usage interval, such as 100 hours, may be set before a regeneration event. In other words, a regeneration event may be performed only after 100 hours of use.

[0289] A difference calculated at step 508 falling outside of an acceptable range may indicate a risk of deposit accumulation. This may be due to the aftertreatment fluid not being adequately broken down by the exhaust gas and / or exhaust gas recirculation area, particularly in the vicinity of the dosing module.

[0290] In response to the difference calculated at step 508 falling outside the acceptable range, as indicated by line 512, the method moves to step 514. At step 514, the variable geometry mechanism and / or bypass control valve are adjusted. Based on the difference falling outside the acceptable range, as calculated at step 508, the variable geometry mechanism and / or bypass control valve can be adjusted to adjust the velocity profile in a specific area. The area can be the location of the dosing module, at which a relatively low velocity may otherwise have the risk of flow separation and suspension of the aftertreatment fluid in the exhaust flow. The area can be another area with an increased risk of deposit accumulation, such as a bend in the turbine outlet channel (or any other location where the aftertreatment fluid may be prone to impact on the wall and have a risk of deposit accumulation). The velocity of the exhaust gas may be relatively low on the inside of the bend, which may increase the risk of aftertreatment fluid suspension (and thereby increase the risk of deposit accumulation). Therefore, the area can be a bend, particularly the inside of the bend. The area can be an impact area (e.g., roughly opposite to the dosing module). The region may be a joint between components, such as a bellows or a flexible tube (e.g., having a corrugated or wrinkled surface). The region may be any region with a step change transition (e.g., not a smooth transition) where vortices are susceptible to forming. The region may be an expansion joint. The region may be one or more of the above-mentioned regions (e.g., multiple different regions may be targeted). For the sake of completeness, it should be understood that adjusting the velocity profile of the exhaust flow in one region may result in a corresponding effect on the velocity profile in another region. However, method 500 proposes to preferentially adjust the velocity profile in a specific region in response to the current velocity profile.

[0291] For a given engine operating condition, the velocity curve can be adjusted to increase (or decrease) the velocity of the exhaust gas to increase (or decrease) the wall shear and increase (or decrease) the convective heat transfer. For example, in the case where step 508 indicates the risk of deposits accumulating near the distribution module, the variable geometry mechanism and / or the bypass control valve can be adjusted to increase the velocity of the exhaust gas near the distribution module. This in turn reduces or eliminates the separation region where the boundary layer of the exhaust gas may be easily separated (or has been separated) from the wall, and produces a recirculation region in which the aftertreatment fluid is suspended. The suspended aftertreatment fluid has the risk of damaging the outlet of the distribution module and the accumulation of deposits. In another example, in the case where high shear stress is required, for example, in an area (such as a bend) where deposits are easy to accumulate, the variable geometry mechanism and / or the bypass control valve can be adjusted to increase the exhaust gas velocity at or just upstream of the area. Therefore, the vortex and the shear stress applied by the exhaust flow can also be increased.

[0292] Steering Figure 21 to Figure 23 , provides plots showing the results of computational fluid dynamics (CFD) simulations. Figure 21 to Figure 23 Each of the graphs in shows a velocity profile at the turbine wheel nut plane (e.g., at the downstream end of the turbine wheel) for three different configurations of wastegate valve position (a wastegate valve is an example of a bypass control valve). For completeness, the engine operating point (e.g., engine speed and load, or engine speed and torque) is the same in each simulation. Figure 21 to Figure 23 The plot corresponds to the one described previously in this paper Figures 11 to 13 Plot the equivalent temperature curve.

[0293] Fig.21 shows the temperature curve when the wastegate valve is closed, Fig. 22 shows the temperature curve when the wastegate valve is 50% open, and Fig.23 The temperature curve is shown when the wastegate valve is 100% open. Figure 21 to Figure 23 It will be appreciated that the position of the wastegate valve has an effect on the velocity profile of the exhaust gas. In particular, by roughly comparing Figure 21 to Figure 23 It will be appreciated that the greater the degree to which the wastegate valve is opened, the higher the velocity across the velocity curve of the exhaust gas. This is at least in part due to the fact that the (bypass / wastegate) exhaust gas has not yet passed through the turbine wheel for expansion and therefore has relatively higher energy than exhaust gas that has passed through the turbine wheel for expansion. Figure 21 to Figure 23 The change in the wastegate valve configuration is indicated to affect both the core of the exhaust flow and the boundary layer of the flow at the wall (e.g., the periphery of the flow near the wall). Fig. 22 and Fig.23 shown), reduce or eliminate Fig.215. The lower velocity wall boundary layer (labeled 522) is visible in FIG. 5. For completeness, at a given engine operating point, when the wastegate valve is open, less exhaust gas is passed through the turbine for expansion. Therefore, downstream of the turbine impeller but before the wastegate passage outlet (e.g., where the bypass exhaust gas rejoins the turbine main flow), a local reduction in exhaust gas velocity is experienced. The velocity of the exhaust gas flow then increases again at the wastegate passage outlet and downstream due to the introduction of the high velocity bypass exhaust gas.

[0294] For the sake of completeness, Fig.21 The feature labeled 520 in FIG. 5 represents the fluid / solid boundary of the computational domain, not a region of very high temperature. Although described in the context of the wastegate valve open position Figure 21 to Figure 23 , but for a fixed geometry turbine, it will be appreciated that a similar effect can be achieved by varying the variable geometry mechanism of the fixed geometry turbine. In particular, opening the variable geometry mechanism reduces the constraints on the turbine, thereby allowing a greater exhaust volume flow (and therefore a higher exhaust velocity, and associated increased shear stress). It will also be appreciated that a similar effect can be achieved by varying the wastegate valve opening position of a variable geometry turbine. Thus, Figure 21 to Figure 23 It is indicated that selective adjustment of the wastegate valve position may be used to adjust the velocity profile of the exhaust gas.

[0295] Now turn to Figure 24 to Figure 26 , three additional speed curves are provided. Figure 24 to Figure 26 The velocity profiles at the outlet of the turbine are shown when the corresponding wastegate valve is in three different configurations. Fig.24 shows the velocity curve when the wastegate valve is in a 100% closed configuration, Fig.25 shows the velocity profile when the wastegate valve is in a 50% open configuration, and Fig.26 The velocity curve is shown when the wastegate valve is in a 100% open configuration. Except that the velocity curve is shown instead of the temperature curve, Figure 24 to Figure 26 Roughly corresponds to Figures 11 to 13 . It should also be noted that Figure 24 to Figure 26 A profile of the tangential / circumferential velocity (ie, swirl velocity) of the exhaust gas in the axial plane is shown.

[0296] If from Figure 24 to Figure 26 As will be appreciated, increasing the degree to which the wastegate valve is opened generally increases the swirl of the exhaust gas across the turbine outlet passage, particularly at the boundary layer of the flow (e.g., the periphery of the flow near the wall). Doing so increases the shear forces exerted by the exhaust gas on the wall and increases convective heat transfer from the exhaust gas flow to the wall.

[0297] Steering Figures 27 to 35, provides plots showing the results of computational fluid dynamics (CFD) simulations. Figures 27 to 35 The risk of deposit accumulation in three different embodiments of an exhaust system is shown for three different configurations of wastegate valve positions (a wastegate valve is an example of a bypass control valve). Figure 27 to Figure 29 Concerning the first embodiment, Figure 30 to Figure 32 relates to the second embodiment, and Figure 33 to Figure 35 It relates to the third embodiment. Each embodiment differs in the position of the dosing module and / or the distribution of the turbine outlet channels. Fig. 27 , Fig.30 and Fig.33 The results are shown for a wastegate valve in a 100% closed configuration, Fig.28 , Fig.31 and Fig.34 The results are shown for a wastegate valve in a 50% open configuration, and Fig.29 , Fig.32 and Fig.35 The results are shown for the wastegate valve in a 100% open configuration, which corresponds to an open position of 7.5° in the illustrated embodiment.

[0298] It will be appreciated that even partially opening the wastegate valve has the effect of moving the risk area for deposit accumulation downstream. Fig. 27 , Fig.30 , Fig.33 ) compared to when the wastegate valve is 100% open (ie, Fig.29 , Fig.32 , Fig.35 ), the risk of deposit accumulation was observed to be reduced by about 20% across the entire plate.

[0299] Figure 36 to Figure 44 Shown above Figures 27 to 35 1 , but indicating the magnitude of the wall shear stress. 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , Fig.38 , Fig.41 and Fig.44 Each figure shows the Fig.36 , Fig.37 , Fig.39 , Fig.40 and Fig.42 , Fig.43 Compared to the significantly larger high shear stress area (e.g., shear zone), the shear zone increases in both size (e.g., length) and strength when the wastegate valve is in a 100% open configuration. This increased shear zone advantageously promotes spreading of the wall film (e.g., spreading to a region of higher wall temperature) and peeling the wall film back into the exhaust flow. Both reduce the likelihood of deposit accumulation.

[0300] Figures 45 to 50 is a velocity plot including streamlines showing the results of a CFD simulation performed on an embodiment of an exhaust system at three different engine operating points (EOPs). Fig.45 and Fig.46 Involving the first EOP, Fig.47 and Fig.48 involves a second EOP, and Fig.49 and Fig.50 Involving the third EOP. Fig.46 , Fig.48 and Fig.50 Each of the pictures in Fig.45 , Fig.47 and Fig.49 Magnified views of the regions of interest in each of the figures: the locations of the dosing modules marked 550, 552, 554.

[0301] by Fig.45 and Fig.46 As an example, there is a recirculation area 551 near the position 550 of the dosing module. The recirculation area 551 is caused by the exhaust flow that has separated from the wall of the turbine outlet channel. Flow separation is also problematic because the dosing module is installed just downstream of a bifurcation or "bump" (e.g., undercut) in the turbine outlet channel. The recirculation area 551 carries the risk of the aftertreatment fluid being suspended in the exhaust flow without being broken down and / or transported downstream, and of deposits accumulating at the outlet of the dosing module. This in turn increases the risk of deposits accumulating in this area, and in particular at the outlet of the dosing module. The separation of the exhaust flow from the wall of the turbine outlet channel is caused by the low velocities in this area and results in a lack of uniformity in the velocity profile in this area. Therefore, Fig.45 and Fig.46 It is indicated that a recirculation region 551 exists at this EOP, and it is desirable to be able to reduce or eliminate the recirculation region 551 at the EOP by adjusting the bypass control valve and / or the variable geometry mechanism.

[0302] and Fig.45 and Fig.46 on the contrary, Fig.47 and Fig.48 The relatively uniform directionality of the streamlines of the exhaust gas near a location of dosing module 552 (eg, in region 553) is shown. Fig.47 and Fig.48 Also shown is a venting region 553, which is close to the effective outlet of the dosing module (e.g., at the periphery of the flow near the wall), indicating (with e.g. Fig.46The exhaust has a relatively high velocity compared to the region 551). In the region 553 near the outlet of the dosing module, the improved uniformity and relatively high velocity of the exhaust directionality advantageously reduce the risk of deposit accumulation at the outlet (e.g., the end) of the dosing module. Described in another way, the higher velocity region 553 of the exhaust at the periphery of the exhaust flow, at a location near the outlet of the dosing module, can be used to clean the outlet of the dosing module. This may be at least in part because the exhaust exerts a relatively high shear force at the outlet of the dosing module (e.g., on it). Similarly, the less chaotic / random directionality of the streamlines reduces the risk of the post-treatment fluid being suspended within the exhaust.

[0303] For completeness, Fig.49 and Fig.50 also shown are the streamlines in the region 555 that remain attached to the wall (i.e., do not separate), thus providing the desired flow field.

[0304] Therefore, Figures 45 to 50 shown is why it is desirable to be able to modify the velocity profile of the exhaust flow, for example, by adjusting (e.g., modulating) the exhaust gas throttle valve and / or the variable geometry mechanism.

[0305] Adjusting (e.g., modulating) at least one of the variable geometry mechanism and the bypass control valve can be used to change the velocity profile at the location of the dosing module (e.g., in response to, for example, the risk of deposit accumulation at the location of the dosing module falling outside the acceptable range). Therefore, adjusting (e.g., modulating) at least one of the variable geometry mechanism and the bypass control valve can be used to reduce the risk of deposit accumulation at the location of the dosing module (specifically, at the outlet of the dosing module (e.g., at the periphery of the flow)). Adjusting at least one of the variable geometry mechanism and the bypass control valve can also be used to change the velocity profile of the exhaust at a location downstream of the dosing module (e.g., increasing the region of deposit accumulation, such as a bend in a pipe / duct).

[0306] The location of the dosing module can be described as the centroid of the outlet of the dosing module and / or the centroid of the opening of the dosing module mount.

[0307] Fig.51Another embodiment of a method 600 according to the present disclosure is disclosed. In a first step 602, the method 600 includes determining a current characteristic of the exhaust gas at a location downstream of a turbine impeller. The current characteristic may be, in particular, a current NOx reduction across one of the aftertreatment devices 218. The current NOx reduction across the aftertreatment device 218 may be measured, calculated, or inferred based on a difference between a measurement of the NOx concentration in the turbine outlet 210 obtained by the turbine outlet sensor 224 and a measurement of the NOx concentration at the outlet of the aftertreatment device 218 obtained by the aftertreatment device outlet sensor 226. The NOx reduction across the aftertreatment device 218 indicates a relative proportion of NOx entering the aftertreatment device 218 that is reduced or reduced by the aftertreatment device 218 before exiting the aftertreatment device 218.

[0308] In a second step 604, a reference characteristic is determined. In the example above, the reference characteristic may be a reference NOx reduction across the aftertreatment devices. In a third step 606, a difference between the current characteristic and the reference characteristic is determined and quantified. In particular, the current NOx reduction across the aftertreatment devices 218 is compared to the reference reduction across the aftertreatment devices 218, and the difference therebetween is quantified.

[0309] In a fourth step 607, the presence of an operating condition of the exhaust system in which the swirl angle of the exhaust gas in the turbine outlet passage is insufficient is identified. The presence of an operating condition of the exhaust system in which the swirl angle of the exhaust gas in the turbine outlet passage is insufficient may be referred to as a "low swirl" operating condition. The low swirl operating condition is identified by comparing the amount of the difference to an acceptable range or threshold. In particular, the amount of the difference between the current NOx reduction across the aftertreatment device 218 and the reference NOx reduction across the aftertreatment device 218 is compared to an acceptable range or threshold. The acceptable range or threshold may be set so that when the current NOx reduction across the aftertreatment device 218 drops below, for example, about 98%, about 95%, or about 90%, a low swirl operating condition is identified to exist. When the NOx reduction across the aftertreatment device 218 falls below such a threshold, this indicates a condition in which the aftertreatment fluid delivered by the dosing module 220 has not been fully decomposed before it reaches the aftertreatment device 218, and therefore the decomposition products (for urea, isocyanic acid, and ammonia) are not available in sufficient amounts within the aftertreatment device 218 to reduce NOx in the exhaust. The lack of decomposition may indicate that the swirl momentum in the exhaust downstream of the turbine impeller 208 is insufficient to provide sufficient mixing of the exhaust gas and the aftertreatment fluid to promote decomposition. Therefore, increasing the amount of swirl momentum in the exhaust may be beneficial.

[0310] In other embodiments, Fig.51As shown in the embodiment of , the current characteristic can be the current operating efficiency of the turbine 204. The current operating efficiency can be determined based on any suitable parameter or parameter group. In particular, the current operating efficiency can be determined based on the turbine inlet temperature, the turbine inlet pressure, the turbine outlet temperature and / or the turbine outlet pressure. The turbine outlet temperature can be measured and / or inferred based on one or more of the turbine inlet temperature, the turbine inlet pressure, the turbine outlet pressure, the compressor power, the engine air mass flow rate and the engine air to fuel ratio. The compressor power can be measured and / or inferred based on the compressor inlet temperature, the compressor outlet temperature, the compressor inlet pressure and / or the compressor outlet pressure.

[0311] In such an embodiment, the reference characteristic may also be the operating efficiency of the turbine 204. When the current operating efficiency is above a certain range or threshold, a low swirl operating condition may be identified. An acceptable range or threshold may be set so that when the turbine efficiency is at least about 70%, about 80%, about 90%, or about 95% of the maximum efficiency of the turbine, a low swirl operating condition is identified to exist. The maximum efficiency of the turbine may be the efficiency of the turbine 204 when it is operated under its most efficient operating conditions, as determined by simulation or testing. When the current operating efficiency of the turbine 204 is high, this may indicate that the exhaust flow in the turbine outlet 210 has a large axial velocity component compared to its angular velocity, and therefore the swirl angle is low. The low swirl angle may reduce the amount of mixing that occurs between the aftertreatment fluid and the exhaust gas, resulting in poor decomposition of the aftertreatment fluid and reducing the NOx conversion in the aftertreatment device 218.

[0312] In some embodiments, the difference based on NOx reduction or reduction and the difference based on turbine efficiency can be used in combination to identify the presence of low swirl operating conditions. Regardless of the current characteristics used to identify low swirl operating conditions, if there is no low swirl operating condition, the method 600 returns to the first step via branch 310. If there is a low swirl operating condition, the method 600 moves to step 308 via branch 312, where the controller 228 outputs a command to the variable geometry mechanism 216 and / or the bypass control valve 212 to adjust the current operating configuration of the variable geometry mechanism 216 and / or the bypass control valve 212. In the case of the variable geometry mechanism 216, this can include moving the variable geometry mechanism to or toward a configuration (e.g., the position of the mechanism, etc.) corresponding to the maximum swirl angle of the exhaust gas leaving the turbine impeller 208. The configuration corresponding to the maximum swirl angle of the exhaust gas can be determined during the design and development of the exhaust system, which is achieved, for example, using a computer simulation of computational fluid dynamics and / or by testing in an engine test unit. In the case of a bypass control valve, this may include moving the bypass control valve 214 to or toward a configuration corresponding to a maximum swirl angle of the exhaust gas in the turbine outlet passage 210. This may be determined during the design and development of the exhaust system, for example using computer simulations such as computational fluid dynamics and / or by testing in an engine test cell. Figures 2 to 6 When the turbines described are the same or have the same configuration, where the bypass flow enters the turbine outlet in a tangential direction, the configuration corresponding to the maximum swirl angle of the exhaust gas in the turbine outlet passage 210 may be the configuration corresponding to the maximum flow through the bypass valve.

[0313] Fig.52 A graph showing the inlet clearance size of the variable geometry mechanism 216 versus the swirl angle in the turbine outlet passage 210. The variable geometry mechanism is particularly a sliding nozzle type variable geometry mechanism, however similar principles would apply to a swing vane type variable geometry mechanism. Fig.52 Three plots of swirl angles obtained at different expansion ratios (ER) of the turbine 204 are shown. The expansion ratio (sometimes referred to as the pressure ratio) of a turbine is the relative ratio of the exhaust pressure upstream of the turbine impeller 208 (i.e., in the turbine inlet 206) to the exhaust pressure downstream of the turbine impeller 208 (i.e., in the turbine outlet 210). It can be seen from the figure that when the variable geometry opening is large, the swirl angle is low, and when the variable geometry opening is small, the swirl angle is high. The swirl angle reaches a peak at an opening distance of about 4 mm. Fig.52 The graph of may be stored as a formula or data set in the controller 228 to enable adjustment of the configuration of the variable geometry mechanism 216 to achieve a desired swirl angle.

[0314] Fig.53 Show Figures 2 to 6 Computational fluid dynamics plot of the turbine at various opening positions of the wastegate. In the first column ( Figure 53 to Figure 55 ), the wastegate is closed and the turbine is operating at high turbine efficiency. It can be seen that the flow in the turbine outlet has a large axial component of velocity compared to the angular component of its velocity. This may indicate that the aftertreatment fluid is not mixed well with the exhaust gas, resulting in reduced NOx conversion in the aftertreatment device 218. In the second column ( Figure 56 to Figure 58 ), the wastegate is partially open. Figures 2 to 6 As discussed, the wastegate passage outlet is configured to introduce the wastegate flow in a direction generally tangential to the turbine axis in the direction of the swirl. By partially opening the wastegate, the wastegate flow provides momentum to the exhaust in a tangential direction, thereby increasing the angular component of velocity and thereby increasing the swirl. Figure 59 to Figure 61 ), the wastegate is fully opened. It can be seen that by fully opening the wastegate, the swirl of the exhaust gas is significantly increased.

[0315] although Figure 53 to Figure 61 The wastegate device shown in introduces flow in a tangential direction and thereby directly affects the angular component of velocity in the turbine outlet, but it will be appreciated that a non-tangential bypass design may be utilized to affect the angular component of velocity in the turbine outlet passage. In particular, opening the wastegate causes the inlet pressure and temperature of the turbine to decrease, thereby reducing the expansion ratio of the turbine. Reducing the expansion ratio results in dynamic changes in the exhaust gas leaving the turbine wheel, which will result in changes in the axial velocity and the angular velocity. Therefore, in a wastegate turbine that lacks a tangential wastegate passage outlet, the swirl angle of the exhaust gas in the turbine passage outlet may still be adjusted by adjusting the expansion ratio of the turbine using the wastegate.

[0316] Fig.62 A three-dimensional view of an exhaust system 650 is shown, which includes a turbine 652, a down pipe 654, and an SCR catalyst 656. The figure further shows the locations of a plurality of planes P1 to P8 located at various points along the down pipe 654 before the SCR catalyst 656.

[0317] Fig.63A graph showing the relative amount of aftertreatment fluid decomposition at each of planes P1 to P8 for three operating configurations of the wastegate (i.e., closed, 50% open, and fully open). It can be seen that for plane P2 forward, the amount of reductant decomposition occurring before the plane increases with the increase in the wastegate opening. As described above, the increased wastegate opening increases the swirl of the exhaust gas in the downcomer 654, which improves mixing and causes more heat transfer to the aftertreatment fluid. In addition, because the wastegate flow has not yet passed through the turbine impeller, the wastegate flow is hot and therefore also provides heat to the aftertreatment fluid. Increased heat transfer to the aftertreatment fluid increases the energy available to cause the urea component of the aftertreatment fluid to decompose into the reductant (isocyanate and ammonia) required to support NOx reduction or reduction in the SCR catalyst 656. Increasing the amount of mixing and heat transfer to the aftertreatment fluid is particularly advantageous at low operating temperatures, where less heat is available and it generally takes longer for decomposition to occur.

[0318] Fig.64 A graph showing the relative uniformity index (UI) of the exhaust gas at each of the planes P1 to P8 under three opening configurations of the wastegate. The uniformity index is a measure of how evenly the aftertreatment fluid and / or the decomposed reducing agent (isocyanate and ammonia) are distributed throughout the exhaust gas. A higher uniformity index indicates a more even distribution and promotes more efficient operation of the SCR catalyst 656. As can be seen from the figure, for the forward plane P2, the increased wastegate opening increases the swirl of the exhaust gas in the downcomer 654, resulting in improved mixing and thus improved uniformity index. Increasing the uniformity index is particularly beneficial for improving SCR reduction performance at higher operating temperatures. In addition, improving the uniformity index can enable the downcomer 654 to be made shorter, resulting in a saving in space requirements in the engine compartment.

[0319] Fig.65 A graph showing the relative amount of aftertreatment fluid breakdown at each of planes P1 to P8 for three different swirl angles in the turbine outlet (i.e., 18.5°, 31.0°, and 36.4°). Likewise, it can be seen that for plane P2 forward, increasing the swirl angle increases the amount of aftertreatment fluid breakdown. As discussed above with respect to Fig.52 and Fig.53 As explained, the swirl angle may be adjusted based on operation of the variable geometry mechanism and / or the bypass control valve.

[0320] It should be understood that using the above techniques, the swirl of the exhaust gas in the turbine outlet can be modulated to maintain optimal mixing over a range of engine operating conditions. In addition, this can be achieved without the need for additional mixing elements or the like. Typically, such mixing elements are only designed for "worst case" operating conditions to ensure adequate mixing is provided under all engine operating conditions. However, this causes additional back pressure over the operating range of the engine. This additional back pressure can be avoided using the techniques described herein, resulting in improved system efficiency.

[0321] Fig.66 Another embodiment of a method 700 according to the present disclosure is disclosed. In a first step 702, the method 700 includes: determining a current characteristic of the exhaust gas at a location downstream of the turbine impeller. The current characteristic may be in particular an excess energy ratio (EER). In general, the EER is the ratio of the total energy available in the exhaust gas to the energy required to completely decompose the aftertreatment fluid entrained by the exhaust gas. The EER may be expressed as the heat energy of the exhaust gas divided by the sum of the heating energy and evaporation energy of water and the heating energy and evaporation energy of urea. This may be represented by the formula previously set forth above. Thus, the EER may be calculated or inferred based on the temperature of the exhaust gas at the turbine outlet, the mass flow rate of the engine, and the mass flow rate of the aftertreatment fluid, all of which may be sensed by sensors in the exhaust system and provided to the controller 228.

[0322] In a second step 704, a reference characteristic is determined. The reference characteristic may be an excess energy ratio (EER). In a third step 706, a difference between the current characteristic and the reference characteristic is determined and quantified. In particular, the current EER may be compared to a target EER, and the difference between the current EER and the target EER may be quantified.

[0323] In a fourth step 707, the existence of an operating condition of the exhaust system in which insufficient shear stress is applied to the wall of the exhaust system by the exhaust gas at a specific location is identified. An operating condition of the exhaust system in which insufficient shear stress is applied to the wall of the exhaust system by the exhaust gas at a specific location can be referred to as a "low shear" operating condition. The low shear operating condition is identified by comparing the amount of the difference with an acceptable range or threshold. In particular, the amount of the difference between the current EER and the reference EER is compared with an acceptable range or threshold. Typically, an EER of about 30 is considered to correspond to a high shear condition in the turbine outlet passage. An acceptable range or threshold can be set to identify the presence of a low shear operating condition when the current EER drops below, for example, about 10, about 15, or about 20. The lower the EER, the lower the shear force on the wall of the turbine outlet, and the greater the chance of urea deposits solidifying. Under some operating conditions of the exhaust system, it is desirable to increase the shear force in the turbine outlet. Increasing the shear force improves the heat transfer to any aftertreatment fluid that impacts the wall of the turbine outlet passage (or downpipe), thereby promoting the evaporation of the aftertreatment fluid after impact. In addition, the increased shear causes any aftertreatment fluid molecules on the free surface of the impinging fluid to be stripped from the wall and re-entrained in the exhaust. Finally, the increased shear serves to diffuse any impinging aftertreatment fluid, thereby providing a greater surface area for heat transfer. Thus, the increased shear can reduce the chance of deposits solidifying in the turbine outlet and / or downpipe.

[0324] In other embodiments, Fig.58As shown, the current characteristic can be the current operating efficiency of the turbine 204. The current operating efficiency can be determined based on any suitable parameter or parameter group (such as those previously described above). In such an embodiment, the reference characteristic can also be the operating efficiency of the turbine 204. When the current operating efficiency is above a specific range or threshold, a low shear operating condition can be identified. An acceptable range or threshold can be set so that when the turbine efficiency is at least about 70%, about 80%, about 90% or about 95% of the maximum efficiency of the turbine, a low swirl operating condition is identified. The maximum efficiency of the turbine can be the efficiency of the turbine 204 when it is operated under its most efficient operating conditions, as determined by simulation or testing. When the current operating efficiency of the turbine 204 is high, this can indicate that the exhaust flow in the turbine outlet 210 has a large axial velocity component compared to its angular velocity, and therefore the swirl angle is low. Increasing the swirl angle increases the distance that each exhaust particle must travel when they advance through the turbine outlet channel / down pipe, and therefore increases the shearing effect on the wall. Furthermore, while the static component of the turbine outlet pressure is fixed by the atmospheric pressure applied to the tailpipe, the dynamic component of the pressure depends on the velocity and density of the exhaust gas. Thus, increasing the path distance (by increasing the swirl angle) results in a corresponding increase in particle velocity. Accelerating the exhaust gas particles further increases the shear applied to the walls of the turbine outlet, thereby providing the advantages listed above.

[0325] In still other embodiments, the current characteristic may be the turbine inlet pressure and the reference characteristic may be the turbine inlet pressure.A low shear operating condition may be identified when the current operating efficiency is above a certain range or threshold.

[0326] In some embodiments, low shear operating conditions can be identified based on one or more of EER, turbine efficiency, or turbine inlet pressure. Regardless of the current characteristics used to identify low shear operating conditions, if low shear operating conditions do not exist, method 700 returns to the first step via branch 710. If there is a low swirl operating condition, method 700 moves to step 708 via branch 712, where controller 228 outputs a command to the variable geometry mechanism 216 and / or bypass control valve 212 to adjust the current operating configuration of the variable geometry mechanism 216 and / or bypass control valve 212. In the case of a variable geometry mechanism 216, this may include moving the variable geometry mechanism to or toward a configuration (e.g., the position of the mechanism, etc.) corresponding to the maximum shear applied by the exhaust gas at a specific location of the turbine outlet passage 210. The configuration corresponding to the maximum shear at a specific location can be determined during the design and development of the exhaust system, for example, using a computer simulation such as computational fluid dynamics and / or by testing in an engine test unit. In the case of a bypass control valve, this may include moving the bypass control valve 214 to or toward a configuration corresponding to the maximum shear applied by the exhaust gas at a particular location in the turbine outlet passage 210. This may be determined during the design and development of the exhaust system, for example using computer simulations such as computational fluid dynamics and / or by testing in an engine test cell. Figures 2 to 6 When describing turbines that are the same or have the same configuration, where the bypass flow enters the turbine outlet in a tangential direction, the configuration corresponding to the maximum shear of the exhaust gas in the turbine outlet passage 210 may be the configuration corresponding to the maximum flow through the bypass valve.

[0327] Figure 70 to Figure 72 Computational fluid dynamics plots of wall shear within the interior of turbine outlet 750 are shown for three different wastegate operating conditions. Turbine outlet 750 is particularly Figures 2 to 6 The turbine outlet of the turbine described. The upper left plot ( Fig.70 ) shows the wall shear when the wastegate is closed, and the upper right plot ( Fig.71 ) shows the wall shear when the wastegate is at 50% open, and the lower left plot ( Fig.72 ) shows the wall shear when the wastegate is fully open. The wastegate flow enters the turbine outlet 750 via the wastegate passage outlet, the location of which is generally indicated by reference numeral 752.

[0328] Reference numeral 754 identifies a specific location of the turbine outlet passage 750. The specific location 754 is an area of ​​the turbine outlet passage wall that is positioned directly opposite to a dosing module (not shown) that delivers the aftertreatment fluid to the turbine outlet passage 750. During use, the momentum imparted to the aftertreatment fluid by the dosing module carries the aftertreatment fluid through the turbine outlet 750, so that some of the aftertreatment fluid may impact the wall of the turbine outlet 750 at location 754. As can be seen from the drawing, when the wastegate passage is closed, the shear stress at location 754 is low. Therefore, there is a risk that urea contained in the aftertreatment fluid may solidify at location 754 and cause a restriction in the turbine outlet 750. However, when the wastegate passage is partially or fully opened, the shear force at location 754 increases. Increasing the shear force applied by the exhaust gas to location 754 serves to diffuse any impacted fluid, increase heat transfer to the impacted fluid, and re-entrain molecules from the free surface of the impacted fluid into the flow. Thus, the risk of solidification of the deposit at location 754 is mitigated by increasing the shear forces at location 754 .

[0329] Figure 73 to Figure 82 Further computational fluid dynamics plot showing wall shear stress in an exhaust system. Figure 73 to Figure 82 and Figure 70 to Figure 72 The difference is that they show the turbine outlet passage 750 and the downcomer 756. In the first column ( Figure 73 to Figure 75 ) with the wastegate closed, in the second bank ( Figure 76 to Figure 79 ) the wastegate is partially open and in the third bank ( Figure 80 to Figure 82 ), the wastegate is fully open. Likewise, it can be seen that by opening the wastegate, the shear applied to one or more specific locations of the turbine outlet and / or downpipe can be increased.

[0330] It should be appreciated that the above techniques thus allow a bypass and / or variable geometry mechanism to be used to adjust shear forces in an exhaust system at a specific location in the exhaust system. The effects of wastegate and / or variable geometry operating conditions on shear forces can be modeled using simulation or testing and stored in a controller as one or more formulas or data sets. Thus, the controller can modulate actuation of the bypass control valve and / or variable geometry mechanism to mitigate deposit formation within a range of operating conditions of the exhaust system.

[0331] Go to Fig.83, a flow chart schematically indicating a method 800 according to another embodiment of the present disclosure is provided. In this embodiment, the current characteristic and the reference characteristic are of an aftertreatment device (e.g., a catalytic converter). The determined characteristic of the aftertreatment device may be a temperature of the aftertreatment device (i.e., the current temperature). The determined characteristic of the aftertreatment device may be a metric indicating a need to regenerate the aftertreatment device. The determined characteristic of the aftertreatment device may be an efficiency of the aftertreatment device.

[0332] In particular, the aftertreatment device may be an aftertreatment device of any exhaust system previously described above. For example, the aftertreatment device may be Figure 7 In particular, the turbine may be any of the exhaust system turbines previously described above. For example, the turbine may be Figure 7 The turbine 204 of the embodiment, or Figures 2 to 6 A turbine of an embodiment.

[0333] In a first step 802, a current characteristic of the aftertreatment device is determined. The current characteristic may be determined by directly measuring the characteristic (e.g., by measuring the temperature using a temperature sensor such as a thermocouple). Alternatively, the current characteristic may be determined based on a measurement of another characteristic (whether a characteristic of the aftertreatment device or other characteristic, such as, for example, a characteristic of the exhaust mixture through the exhaust system), processing the measurement, and inferring the current characteristic of the aftertreatment device from the processing. For example, the current characteristic may be determined based on one or more of the following: a time period since a previous regeneration event, a time period since engine ignition, a current NOx reduction on one or more catalytic converters, a pressure drop across the turbine, and / or a turbine inlet pressure. An unexpected (e.g., increased) pressure drop across the turbine and / or an increased turbine inlet temperature may indicate an accumulation of deposits (e.g., in the aftertreatment device). The current characteristic of the aftertreatment device may be based on one or more characteristics of the exhaust (e.g., a temperature of the exhaust, a pressure drop across the aftertreatment device, a reduction in NOx across the aftertreatment device, etc.).

[0334] Transitioning to step 804, a reference characteristic of the exhaust gas is determined. It will be appreciated that the reference characteristic preferably corresponds to the current characteristic in terms of the type of characteristic used (eg, temperature of the aftertreatment device, as described above).

[0335] Going to step 806, the difference between the current characteristic and the reference characteristic is determined. In the case where the current characteristic is a single characteristic at a single spatial location, the difference can be a subtraction equation. In the case where the current characteristic includes multiple characteristics, the difference can be calculated based on a statistical comparison.

[0336] At step 808, the difference determined in step 806 is analyzed to determine whether the difference falls outside of an acceptable range. The acceptable range may be based on an allowable level of degradation of the aftertreatment device (e.g., a range of acceptable operating efficiencies of the aftertreatment device). The acceptable range may be based on a temperature range in which the catalyst functions but does not degrade. The acceptable range may be an allowable pressure drop across the aftertreatment device (e.g., indicating that no significant deposits have accumulated). The acceptable range may be an acceptable reduction in NOx across the aftertreatment device.

[0337] If the difference calculated at step 808 does not fall outside of the acceptable range, the method returns to step 802, as indicated by line 810. There may be a delay before the method 800 restarts at step 802. Alternatively, the method 800 may continue to cycle repeatedly without any delay. The method is preferably performed periodically. The method may be performed in a dynamic periodic manner. For example, a minimum target usage interval, such as 100 hours, may be set before a regeneration event. In other words, a regeneration event may be performed only after 100 hours of use.

[0338] The difference calculated at step 808 falling outside the acceptable range may indicate a need to regenerate the aftertreatment device. In response to the difference calculated at step 808 falling outside the acceptable range, as indicated by line 812, the method moves to step 814. At step 814, the variable geometry mechanism and / or the bypass control valve are adjusted. Based on the difference falling outside the acceptable range, as calculated at step 808, the variable geometry mechanism and / or the bypass control valve may be adjusted to increase the temperature of the aftertreatment device. The temperature of the aftertreatment device may be increased to, for example, at least about 500°K, at least about 700°K, and at least about 800°K. In order to regenerate the aftertreatment device, the temperature is increased and then maintained at the increased level. The temperature may be increased within at least about 600 seconds, more preferably within at least about 1200 seconds, and more preferably within at least about 1800 seconds. The variable geometry mechanism and / or the bypass control valve may be adjusted within at least about 600 seconds, more preferably within at least about 1200 seconds, and more preferably within at least about 1800 seconds.

[0339] The effect of increasing the temperature of the aftertreatment device and maintaining the increased temperature for a period of time is that the aftertreatment device is regenerated. Deposits within the aftertreatment device are thereby burned off (e.g., oxidized), thereby improving the operating efficiency of the aftertreatment device. The deposits include soot. A typical regeneration temperature for soot is about 800°K, but if sufficient levels of NO are present, the regeneration temperature may be increased. 2 , the regeneration temperature can be reduced to about 500°K.

[0340] In a preferred embodiment, in response to step 808 identifying that the difference falls outside of an acceptable range, the bypass control valve is adjusted. In particular, the bypass control valve is opened so that high energy and high temperature (bypassed) exhaust gas that has not yet expanded across the turbine wheel is placed in fluid communication with the aftertreatment device. When used in conjunction with the wastegate passage geometry, the exhaust gas velocity from the wastegate passage into the turbine outlet passage (e.g., tangential reintroduction of bypassed exhaust gas) is increased. The engine speed may also be adjusted (e.g., tilted) prior to adjusting the bypass control valve.

[0341] It has been found that due to the use of bypassed exhaust gas, regeneration of the aftertreatment device as described above is relatively fast compared to known methods.Otherwise, regeneration may be defined as the aftertreatment device reaching a target temperature and then remaining at that target temperature for at least a period of time.

[0342] The above-mentioned regeneration may be particularly applicable to a catalytic converter (an example of an aftertreatment device).

[0343] Throughout this document, adjusting the position of the variable geometry mechanism or bypass control valve may additionally be described as adjusting the expansion ratio across the turbine.

[0344] For any of the above embodiments: the bypass control valve may be an eWastegate (eg, an electronically actuated wastegate), a rotary control valve, a pneumatically controlled wastegate valve, or various other valves.

[0345] For any of the above embodiments: Exhaust gas that has traveled through the bypass of the bypass control valve is preferably discharged into the turbine outlet passage upstream of or at a corresponding position of the distribution module. Stated another way, the wastegate passage outlet is preferably upstream of the distribution module (e.g., the outlet of the distribution module or the main impact zone defined by the distribution module) or substantially aligned with the distribution module (e.g., covering the distribution module).

[0346] As a general principle, in all of the above embodiments, it should be understood that because the dosing module 220 is positioned close to the turbine wheel 208, this ensures that the aftertreatment fluid is delivered to the exhaust system in an area that has relatively high temperatures and flow velocities and is severely affected by the operating properties of the variable geometry mechanism 216 and / or the bypass control valve 214. The above control method will provide a significant impact on the flow properties (velocity, swirl, temperature, etc.) near the area where the aftertreatment fluid is delivered. Therefore, the control method described herein is particularly suitable for and advantageous in a dosing system that performs dosing close to the turbine wheel (e.g., within 10 turbine outlet inducer diameters or less).

Claims

1. A method of operating an exhaust system for receiving exhaust gas from an internal combustion engine, the exhaust system include: a turbine configured to receive exhaust gas from the internal combustion engine, the turbine comprising a turbine wheel configured to extract energy from the exhaust gas; a dosing module configured to deliver an aftertreatment fluid to the exhaust gas at a location downstream of the turbine wheel; at least one of a variable geometry mechanism and a bypass control valve, The variable geometry mechanism is configured to control exhaust gas flow delivered to the turbine wheel; as well as The bypass control valve is configured to bypass a portion of the exhaust gas from a location upstream of the turbine impeller to a location downstream of the turbine impeller; and A controller configured to execute the method, the method comprising: determining a current characteristic of the exhaust gas at a location downstream of the turbine wheel; determining a difference between a current characteristic of the exhaust gas at the location downstream of the turbine wheel and a reference characteristic of the exhaust gas at the location downstream of the turbine wheel; and In response to the difference, the at least one of the variable geometry mechanism and the bypass control valve is adjusted.

2. The method according to claim 1, in, Determining the current characteristics includes: measuring a quantity of one or more characteristics of an internal combustion engine system in which the exhaust system is incorporated; processing the measured one or more quantities in a computing operation; and The current characteristic of the exhaust gas is inferred from the calculating operation.

3. The method according to claim 2, in, Measuring the one or more characteristics of the exhaust gas includes measuring one or more of: Turbine inlet pressure; Turbine inlet temperature; Turbine outlet pressure; Turbine outlet temperature; Engine speed; Throttle position; Engine air mass flow; Engine inlet pressure; Engine inlet temperature; NOx concentration; Catalyst gas temperature; Engine fuel flow; Engine air flow; Engine boost pressure; Engine load; Engine cylinder temperature; Engine cylinder pressure; Engine fuel pressure; or Turbine rotation rate.

4. The method according to any one of the preceding claims, in, The current characteristic of the exhaust gas includes a current temperature profile of the exhaust gas, and the reference characteristic of the exhaust gas includes a reference temperature profile of the exhaust gas.

5. The method according to claim 4, in, The current temperature profile of the exhaust gas is determined based on one or more of: a current NOx reduction across one or more catalytic converters; an inlet exhaust temperature of an aftertreatment device; an outlet exhaust temperature of the aftertreatment device; a temperature of the exhaust gas within the aftertreatment device; and an excess energy ratio (EER).

6. The method according to claim 5, in, If a breakup rate of aftertreatment fluid droplets in the exhaust flow falls outside an acceptable range and / or if an activation time of the aftertreatment device falls outside an acceptable range, adjusting the at least one of the variable geometry mechanism and the bypass control valve to increase a temperature of the exhaust gas at a core of the exhaust flow.

7. The method according to claim 5, in, If the risk of deposit accumulation falls outside of an acceptable range, the at least one of the variable geometry mechanism and the bypass control valve is adjusted to increase a temperature of the exhaust gas at a periphery of the exhaust gas flow.

8. The method according to any one of the preceding claims, in, The current characteristic of the exhaust gas comprises a current velocity profile of the exhaust gas, and the reference characteristic of the exhaust gas comprises a reference velocity profile of the exhaust gas.

9. The method according to claim 8, in, determining the current characteristic of the exhaust gas based on one or more of: a pressure ratio across the turbine; a turbine inlet pressure; a turbine outlet pressure; a turbine inlet temperature; a turbine outlet temperature; Turbine rotation rate and engine mass flow.

10. The method according to claim 9, in, If the risk of deposit accumulation falls outside of an acceptable range, the at least one of the variable geometry mechanism and the bypass control valve is adjusted to change the velocity profile at the location downstream of the turbine impeller.

11. The method according to claim 10, in, The position downstream of the turbine wheel is the position of the dosing module.

12. The method according to claim 10 or 11, in, The location downstream of the turbine wheel is downstream of the dosing module.

13. The method according to any one of the preceding claims, in, The method further comprises: identifying the presence of an operating condition of the exhaust system that produces an insufficient swirl angle of the exhaust gas in the turbine outlet passage based on the difference; and In response to identifying the operating condition, the at least one of the variable geometry mechanism and the bypass control valve is adjusted to increase a swirl angle of the exhaust gas in the turbine outlet passage.

14. The method according to claim 13, in, Adjusting the variable geometry mechanism to increase the swirl angle of the exhaust gas in the turbine outlet passage includes moving the variable geometry mechanism to or toward a configuration corresponding to a maximum swirl angle of the exhaust gas in the turbine outlet passage.

15. The method according to claim 13, in, Adjusting the bypass control valve to increase the swirl angle of the exhaust gas in the turbine outlet passage includes: moving the bypass control valve to a configuration corresponding to a maximum swirl angle of the exhaust gas in the turbine outlet passage, or moving toward a configuration corresponding to a maximum swirl angle of the exhaust gas in the turbine outlet passage.

16. The method according to any one of claims 13 to 15, in, The current characteristic of the exhaust gas comprises a current NOx reduction across one or more catalytic converters, and wherein the reference characteristic of the exhaust gas comprises a reference NOx reduction across the one or more catalytic converters.

17. The method according to claim 16, in, When the NOx reduction across the one or more catalytic converters drops below about 98%, about 95%, or about 90%, an operating condition of the exhaust system that produces insufficient exhaust swirl momentum about the centerline of the turbine outlet passage is identified.

18. The method according to any one of claims 13 to 17, in, The current characteristic of the exhaust gas includes a turbine efficiency, and the reference characteristic of the exhaust gas includes a reference turbine efficiency.

19. The method according to claim 18, in, An operating condition of the exhaust system that produces insufficient exhaust swirl momentum about the centerline of the turbine outlet passage is identified when the turbine efficiency is at least about 70%, about 80%, about 90% or about 95% of the maximum efficiency of the turbine.

20. The method according to any one of the preceding claims, in, The method further comprises: identifying, based on the difference, the existence of an operating condition of the exhaust system in which insufficient shear stress is applied by the exhaust gas to a wall of the exhaust system at a particular location; and In response to identifying the operating condition, the at least one of the variable geometry mechanism and the bypass control valve is adjusted to increase an amount of shear stress applied by the exhaust gas to the wall of the exhaust system at the particular location.

21. The method according to claim 20, in, Adjusting the variable geometry mechanism to increase the amount of shear stress applied by the exhaust gas to the wall of the exhaust system at the particular location includes moving the variable geometry mechanism to or toward a configuration corresponding to a maximum shear stress of the exhaust gas at the particular location.

22. The method according to claim 20, in, Adjusting the bypass control valve to increase the amount of shear stress applied by the exhaust gas to the wall of the exhaust system at the specific location includes: moving the bypass control valve to a configuration corresponding to a maximum shear stress of the exhaust gas at the specific location, or moving toward a configuration corresponding to a maximum shear stress of the exhaust gas at the specific location.

23. A method according to any one of claims 24 to 22, in, The current characteristic of the exhaust gas includes an excess energy ratio (EER), and the reference characteristic of the exhaust gas includes a reference excess energy ratio.

24. The method according to claim 23, in, When the excess energy ratio is less than about 10, about 15, or about 20, an operating condition of the exhaust system is identified where insufficient shear stress is applied by the exhaust gas to the wall of the exhaust system at the particular location.

25. The method according to any one of claims 20 to 24, in, The current characteristic of the exhaust gas includes a turbine efficiency, and the reference characteristic of the exhaust gas includes a reference turbine efficiency.

26. The method according to claim 25, in, When the turbine efficiency is at least about 70%, about 80%, about 90% or about 95% of the maximum efficiency of the turbine, an operating condition of the exhaust system is identified in which insufficient shear stress is applied to the wall of the exhaust system at the particular location by the exhaust gas.

27. The method according to any one of claims 20 to 26, in, The current characteristic of the exhaust gas comprises a turbine inlet pressure, and the reference characteristic of the exhaust gas comprises a reference turbine inlet pressure.

28. The method according to any one of the preceding claims, in, The turbine comprises: a turbine outlet passage configured to receive exhaust gas from the turbine wheel, the exhaust gas received from the turbine wheel defining a turbine body flow; and a bypass passage configured to receive exhaust gas from a location upstream of the turbine impeller and deliver the exhaust gas to the turbine outlet passage, the exhaust gas received by the bypass passage defining a bypass flow, the bypass control valve configured to adjust a flow rate of the bypass flow through the bypass passage; wherein the turbine wheel imparts a swirl momentum to the turbine body flow, the swirl momentum of the turbine body flow defining a positive angular direction, and wherein the bypass passage is configured to deliver the bypass flow to the turbine outlet passage in a direction that causes the bypass flow to swirl in the positive angular direction about a centerline of the turbine outlet passage; Wherein, the method further comprises: Based on the difference, identifying the presence of an operating condition of the exhaust system that produces insufficient exhaust swirl momentum about the centerline of the turbine outlet passage; and The bypass control valve is adjusted to increase delivery of bypass flow to the turbine outlet passage.

29. The method according to any one of the preceding claims, in, The turbine comprises: a turbine outlet passage configured to receive exhaust gas from the turbine wheel, the exhaust gas received from the turbine wheel defining a turbine body flow; and a bypass passage configured to receive exhaust gas from a location upstream of the turbine impeller and deliver the exhaust gas to the turbine outlet passage, the exhaust gas received by the bypass passage defining a bypass flow, the bypass control valve configured to adjust a flow rate of the bypass flow through the bypass passage; wherein the turbine wheel imparts a swirl momentum to the turbine body flow, the swirl momentum of the turbine body flow defining a positive angular direction, and wherein the bypass passage is configured to deliver the bypass flow to the turbine outlet passage in a direction that causes the bypass flow to swirl in the positive angular direction about a centerline of the turbine outlet passage; Wherein, the method further comprises: based on the difference, identifying the existence of an operating condition of the exhaust system where insufficient shear stress is applied by the exhaust gas to the wall of the exhaust system at a particular location; and In response to identifying the operating condition, the bypass control valve is adjusted to increase delivery of bypass flow to the turbine outlet passage.

30. The method according to claim 29, in, The specific location is a wall of the turbine outlet passage.

31. A method of operating an exhaust system for receiving and treating exhaust gas from an internal combustion engine, the exhaust system include: a turbine configured to receive exhaust gas from the internal combustion engine, the turbine comprising a turbine wheel configured to extract energy from the exhaust gas; a distribution module configured to deliver an aftertreatment fluid to the exhaust gas at a location downstream of the turbine wheel, wherein the distribution module is located within about 10 inducer diameters along the flow axis downstream of a downstream end of the turbine wheel; At least one of a variable geometry mechanism and a bypass control valve: The variable geometry mechanism is configured to control exhaust gas flow delivered to the turbine wheel; and The bypass control valve is configured to bypass a portion of the exhaust gas from a location upstream of the turbine impeller to a location downstream of the turbine impeller; an aftertreatment device located downstream of the turbine and configured to receive and treat exhaust gas from the turbine; and A controller configured to execute the method, the method comprising: determining a current characteristic of the post-processing device; determining a difference between the current characteristic of the post-processing device and a reference characteristic of the post-processing device; and In response to the difference, the at least one of the variable geometry mechanism and the bypass control valve is adjusted to regenerate the aftertreatment device.

32. The method according to claim 31, in, Determining a current characteristic of the aftertreatment device includes determining a temperature of the aftertreatment device.

33. The method according to claim 32, in, Determining the current characteristic of the aftertreatment device is based on one or more of: a time period since a previous regeneration event; a time period since engine ignition; a current NOx reduction on one or more catalytic converters; a turbine inlet pressure; and a pressure drop across the turbine.

34. The method according to claim 32 or 33, in, The method further comprises: determining whether a temperature of the aftertreatment device falls outside an acceptable range; and The at least one of the variable geometry mechanism and the bypass control valve is adjusted to increase a temperature of the aftertreatment device.

35. An exhaust system for receiving exhaust gas from an internal combustion engine, the exhaust system include: a turbine configured to receive exhaust gas from the internal combustion engine, the turbine comprising a turbine wheel configured to extract energy from the exhaust gas; a dosing module configured to deliver an aftertreatment fluid to the exhaust gas at a location downstream of the turbine wheel; at least one of a variable geometry mechanism and a bypass control valve, The variable geometry mechanism is configured to control exhaust gas flow delivered to the turbine wheel; as well as The bypass control valve is configured to bypass a portion of the exhaust gas from a location upstream of the turbine impeller to a location downstream of the turbine impeller; and A controller, the controller being configured to: determining a current characteristic of the exhaust gas at a location downstream of the turbine wheel; determining a difference between a current characteristic of the exhaust gas at the location downstream of the turbine wheel and a reference characteristic of the exhaust gas at the location downstream of the turbine wheel; as well as In response to the difference, the at least one of the variable geometry mechanism and the bypass control valve is adjusted.

36. The exhaust system according to claim 35, in, The controller is configured to: measuring a quantity of one or more characteristics of the internal combustion engine system in which the exhaust system is incorporated; processing the measured quantity or quantities in a computing operation; as well as The current characteristic of the exhaust gas is inferred from the calculating operation.

37. An exhaust system according to claim 36, in, The controller is configured to measure one or more of the following: Turbine inlet pressure; Turbine inlet temperature; Turbine outlet pressure; Turbine outlet temperature; Engine speed; Throttle position; Engine air mass flow; Engine inlet pressure; Engine inlet temperature; NOx concentration; Catalyst gas temperature; Engine fuel flow; Engine air flow; Engine boost pressure; Engine load; Engine cylinder temperature; Engine cylinder pressure; Engine fuel pressure; or Turbine rotation rate.

38. An exhaust system according to any one of claims 35 to 37, in, The current characteristic of the exhaust gas includes a current temperature profile of the exhaust gas, and the reference characteristic of the exhaust gas includes a reference temperature profile of the exhaust gas.

39. An exhaust system according to claim 38, in, The current temperature profile of the exhaust gas is determined based on one or more of: a current NOx reduction across one or more catalytic converters; an inlet exhaust temperature of an aftertreatment device; an outlet exhaust temperature of the aftertreatment device; a temperature of the exhaust gas within the aftertreatment device; and an excess energy ratio (EER).

40. The exhaust system according to claim 39, in, If a breakup rate of aftertreatment fluid droplets in the exhaust flow falls outside an acceptable range and / or if an activation time of the aftertreatment device falls outside an acceptable range, adjusting the at least one of the variable geometry mechanism and the bypass control valve to increase a temperature of the exhaust gas at a core of the exhaust flow.

41. The exhaust system according to claim 40, in, If the risk of deposit accumulation falls outside of an acceptable range, the at least one of the variable geometry mechanism and the bypass control valve is adjusted to increase a temperature of the exhaust gas at a periphery of the exhaust gas flow.

42. An exhaust system according to any one of claims 35 to 41, in, The current characteristic of the exhaust gas comprises a current velocity profile of the exhaust gas, and the reference characteristic of the exhaust gas comprises a reference velocity profile of the exhaust gas.

43. An exhaust system according to claim 42, in, The controller is configured to determine the current characteristic of the exhaust gas based on one or more of: a pressure ratio across the turbine; a turbine inlet pressure; a turbine outlet pressure; a turbine inlet temperature; Turbine outlet temperature; Turbine rotation rate and engine mass flow.

44. An exhaust system according to claim 43, in, If the risk of deposit accumulation falls outside of an acceptable range, the at least one of the variable geometry mechanism and the bypass control valve is adjusted to change the velocity profile at the location downstream of the turbine impeller.

45. An exhaust system according to claim 44, in, The position downstream of the turbine wheel is the position of the dosing module.

46. ​​An exhaust system according to claim 44 or 45, in, The location downstream of the turbine wheel is downstream of the dosing module.

47. An exhaust system according to any one of claims 35 to 46, in, The controller is configured to: identifying the presence of an operating condition of the exhaust system that produces an insufficient swirl angle of the exhaust gas in the turbine outlet passage based on the difference; as well as In response to identifying the operating condition, the at least one of the variable geometry mechanism and the bypass control valve is adjusted to increase a swirl angle of the exhaust gas in the turbine outlet passage.

48. An exhaust system according to claim 47, in, The controller is configured to adjust the variable geometry mechanism to increase the swirl angle of the exhaust gas in the turbine outlet passage by moving the variable geometry mechanism to or towards a configuration corresponding to a maximum swirl angle of the exhaust gas in the turbine outlet passage.

49. The exhaust system of claim 47, in, The controller is configured to adjust the bypass control valve to increase the swirl angle of the exhaust gas in the turbine outlet passage by moving the bypass control valve to a configuration corresponding to a maximum swirl angle of the exhaust gas in the turbine outlet passage, or toward a configuration corresponding to a maximum swirl angle of the exhaust gas in the turbine outlet passage.

50. An exhaust system according to any one of claims 47 to 49, in, The current characteristic of the exhaust gas comprises a current NOx reduction across one or more catalytic converters, and wherein the reference characteristic of the exhaust gas comprises a reference NOx reduction across the one or more catalytic converters.

51. The exhaust system of claim 50, in, The controller is configured to identify an operating condition of the exhaust system generating insufficient exhaust swirl momentum about the centerline of the turbine outlet passage when the NOx reduction across the one or more catalytic converters drops below approximately 98%, approximately 95%, or approximately 90%.

52. An exhaust system according to any one of claims 47 to 51, in, The current characteristic of the exhaust gas comprises a turbine efficiency, and wherein the reference characteristic of the exhaust gas comprises a reference turbine efficiency.

53. An exhaust system according to claim 52, in, The controller is configured to identify an operating condition of the exhaust system that produces insufficient exhaust swirl momentum about the centerline of the turbine outlet passage when the turbine efficiency is at least approximately 70%, approximately 80%, approximately 90%, or approximately 95% of the maximum efficiency of the turbine.

54. An exhaust system according to any one of claims 35 to 53, in, The controller is also configured to: identifying, based on the difference, the existence of an operating condition of the exhaust system in which insufficient shear stress is applied by the exhaust gas to a wall of the exhaust system at a particular location; as well as In response to identifying the operating condition, the at least one of the variable geometry mechanism and the bypass control valve is adjusted to increase an amount of shear stress applied by the exhaust gas to the wall of the exhaust system at the particular location.

55. An exhaust system according to claim 54, in, The controller is configured to adjust the variable geometry mechanism to increase the amount of shear stress applied by the exhaust gas to the wall of the exhaust system at the specific location by moving the variable geometry mechanism to or toward a configuration corresponding to a maximum shear stress of the exhaust gas at the specific location.

56. An exhaust system according to claim 55, in, The controller is configured to adjust the bypass control valve to increase the amount of shear stress applied by the exhaust gas to the wall of the exhaust system at the specific location by moving the bypass control valve to or toward a configuration corresponding to a maximum shear stress of the exhaust gas at the specific location.

57. An exhaust system according to any one of claims 54 to 56, in, The current characteristic of the exhaust gas includes an excess energy ratio (EER), and the reference characteristic of the exhaust gas includes a reference excess energy ratio.

58. An exhaust system according to claim 57, in, The controller is configured to identify an operating condition of the exhaust system where insufficient shear stress is applied by the exhaust gas to the wall of the exhaust system at the particular location when the excess energy ratio is less than approximately 10, approximately 15, or approximately 20.

59. An exhaust system according to any one of claims 54 to 58, in, The current characteristic of the exhaust gas includes a turbine efficiency, and the reference characteristic of the exhaust gas includes a reference turbine efficiency.

60. The exhaust system of claim 59, in, The controller is configured to identify an operating condition of the exhaust system in which insufficient shear stress is applied to the wall of the exhaust system at the particular location by the exhaust gas when the turbine efficiency is at least about 70%, about 80%, about 90% or about 95% of the maximum efficiency of the turbine.

61. An exhaust system according to any one of claims 54 to 60, in, The current characteristic of the exhaust gas comprises a turbine inlet pressure, and the reference characteristic of the exhaust gas comprises a reference turbine inlet pressure.

62. An exhaust system according to any one of claims 35 to 61, in, The turbine comprises: a turbine outlet passage configured to receive exhaust gas from the turbine wheel, the exhaust gas received from the turbine wheel defining a turbine body flow; and a bypass passage configured to receive exhaust gas from a location upstream of the turbine impeller and deliver the exhaust gas to the turbine outlet passage, the exhaust gas received by the bypass passage defining a bypass flow, the bypass control valve configured to adjust a flow rate of the bypass flow through the bypass passage; wherein the turbine wheel imparts a swirl momentum to the turbine body flow, the swirl momentum of the turbine body flow defining a positive angular direction, and wherein the bypass passage is configured to deliver the bypass flow to the turbine outlet passage in a direction that causes the bypass flow to swirl in the positive angular direction about a centerline of the turbine outlet passage.

63. An exhaust system according to claim 62, in, The controller is also configured to: Based on the difference, identifying the presence of an operating condition of the exhaust system that produces insufficient exhaust swirl momentum about the centerline of the turbine outlet passage; and The bypass control valve is adjusted to increase delivery of bypass flow to the turbine outlet passage.

64. The exhaust system of claim 62, in, The controller is also configured to: identifying, based on the difference, the existence of an operating condition of the exhaust system in which insufficient shear stress is applied by the exhaust gas to the wall of the exhaust system at a particular location; as well as In response to identifying the operating condition, the bypass control valve is adjusted to increase delivery of bypass flow to the turbine outlet passage.

65. An exhaust system according to claim 64, in, The specific location is a wall of the turbine outlet passage.

66. An exhaust system for receiving and treating exhaust gas from an internal combustion engine, the exhaust system include: a turbine configured to receive exhaust gas from the internal combustion engine, the turbine comprising a turbine wheel configured to extract energy from the exhaust gas; a distribution module configured to deliver an aftertreatment fluid to the exhaust gas at a location downstream of the turbine wheel, wherein the distribution module is located within about 10 inducer diameters along the flow axis downstream of a downstream end of the turbine wheel; At least one of a variable geometry mechanism and a bypass control valve: The variable geometry mechanism is configured to control exhaust gas flow delivered to the turbine wheel; and The bypass control valve is configured to bypass a portion of the exhaust gas from a location upstream of the turbine impeller to a location downstream of the turbine impeller; an aftertreatment device located downstream of the turbine and configured to receive and treat exhaust gas from the turbine; and A controller, the controller being configured to: determining a current characteristic of the post-processing device; determining a difference between the current characteristic of the post-processing device and a reference characteristic of the post-processing device; and In response to the difference, the at least one of the variable geometry mechanism and the bypass control valve is adjusted to regenerate the aftertreatment device.

67. An exhaust system according to claim 66, in, The controller is configured to determine a current characteristic of the aftertreatment device by determining a temperature of the aftertreatment device.

68. An exhaust system according to claim 67, in, The controller is configured to determine the current characteristic of the aftertreatment device based on one or more of: a period of time since a previous regeneration event; a period of time since engine ignition; a current NOx reduction on one or more catalytic converters; a turbine inlet pressure; and the pressure drop across the turbine.

69. An exhaust system according to claim 67 or 68, in, The controller is also configured to: determining whether a temperature of the post-processing device falls outside an acceptable range; as well as The at least one of the variable geometry mechanism and the bypass control valve is adjusted to increase a temperature of the aftertreatment device.

70. An exhaust system according to any one of claims 35 to 69, in, The distribution module is located downstream of the downstream end of the turbine wheel along the flow axis within about 10 inducer diameters.

71. An exhaust system according to any one of claims 35 to 70, in, The dosing module is arranged at a diverging portion of the turbine outlet passage.

72. An exhaust system according to any one of claims 35 to 71, in, The dosing module is mounted to the turbine, or to a duct downstream of the turbine.

73. An exhaust system according to any one of claims 35 to 72, in, The turbine comprises: a turbine housing defining a turbine inlet passage and a turbine wheel chamber; and A connection adapter is coupled to the turbine housing and at least partially defines the turbine outlet passage.

74. An exhaust system according to claim 73, in, The dosing module is mounted to the connection adapter.

75. A turbocharger system, include: a compressor, the compressor comprising a compressor housing and a compressor impeller; a bearing housing configured to support the shaft for rotation about an axis; and An exhaust system according to any one of claims 35 to 74; Therein, the compressor impeller and the turbine impeller are coupled to the shaft in power communication with each other.

76. An engine device, include: internal combustion engine; and The turbocharger system of claim 75; Therein, the turbocharger is configured to receive exhaust gas from the internal combustion engine.

77. A controller for an exhaust system receiving exhaust gas from an internal combustion engine, the exhaust system include: a turbine, the turbine comprising a turbine wheel; and at least one of a variable geometry mechanism and a bypass control valve; The controller is configured to: determining a current characteristic of the exhaust gas at a location downstream of the turbine wheel; determining a difference between a current characteristic of the exhaust gas at the location downstream of the turbine wheel and a reference characteristic of the exhaust gas at the location downstream of the turbine wheel; as well as In response to the difference, the at least one of the variable geometry mechanism of the turbomachine and the bypass control valve of the turbomachine is adjusted.

78. A controller for an exhaust system receiving exhaust gas from an internal combustion engine, the exhaust system include: a turbine, the turbine comprising a turbine wheel; at least one of a variable geometry mechanism and a bypass control valve; and an aftertreatment device downstream of the turbine and configured to receive and treat exhaust gas from the turbine; The controller is configured to: determining a current characteristic of the post-processing device; determining a difference between the current characteristic of the post-processing device and a reference characteristic of the post-processing device; and In response to the difference, at least one of the variable geometry mechanism of the turbine and a bypass control valve of the turbine is adjusted.

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