NOX sensor for turbomachine

Abstract

An exhaust conduit for an exhaust system of an internal combustion engine is provided. The exhaust conduit comprises: a main channel for traveling a main flow of exhaust gas through the exhaust conduit; a chamber configured to receive a component portion of the exhaust gas separated from a main stream of the exhaust gas. A mounting point is provided in the chamber for mounting an exhaust gas sensor. The chamber is configured to vary the velocity and / or pressure of the exhaust gas traveling through the chamber.

Description

[0001] The present invention relates to an exhaust duct for an exhaust system of an internal combustion engine (i.e., an internal combustion engine), a turbine housing comprising such an exhaust duct, a turbocharger comprising such an exhaust duct or turbine housing, an internal combustion engine comprising such a turbocharger, turbine housing or exhaust duct, a method of measuring properties of the exhaust gas of an internal combustion engine, an alternative exhaust duct for an exhaust system of an internal combustion engine, and a shield for an exhaust gas sensor. The present invention is particularly, but not exclusively, applicable to turbocharged internal combustion engines.

[0002] Turbochargers are used in internal combustion engine systems to increase the pressure of intake air entering the engine to a pressure above atmospheric pressure. This is called "boosting." By increasing the pressure of intake air entering the engine, more oxygen is available in the engine to support the combustion of a greater amount of fuel and thereby increase 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 impart 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 synchronously. 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 travels through the turbine, causing the turbine impeller to rotate. The rotation of the turbine impeller drives the compressor impeller, which is used to compress the intake air as it is delivered to the intake manifold.

[0004] The exhaust gas 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 an exhaust aftertreatment system designed to remove harmful substances from the exhaust gas.

[0005] Typically, an 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 usually includes a large number of narrow passages, which are made of materials selected to support the chemical reaction of removing NOx from the exhaust. The narrow passage provides a large surface area for the catalytic reaction to occur. There are several types of catalytic reducers on the market, such as two-way catalytic reducers, three-way or 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 SCRs, 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 usually 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 often referred to as Diesel Exhaust Fluid (DEF) and are generally available under the registered trademark AdBlue.

[0006] Conventionally, 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 includes a relatively large cross-sectional area compared to the width of a standard exhaust pipe. Exhaust gas entering the decomposition chamber expands, resulting in a decrease in exhaust gas velocity and an increase in exhaust gas pressure. The rapid expansion of the exhaust gas results in the formation of turbulent eddies. DEF is then injected into the decomposition chamber, after which the turbulent eddies cause the DEF to mix with the exhaust gas. 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 transferred to the SCR.

[0008] If the exhaust and DEF are not mixed sufficiently, 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 some 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 that is configured to produce additional turbulence. However, the additional turbulence caused by the mixing plate and the fluid friction applied to the exhaust by the mixing plate will produce back pressure on the exhaust in the decomposition chamber. This back pressure is transmitted upstream and acts to increase the pumping work required by the internal combustion engine and thereby reduce the overall efficiency of the engine system. Therefore, there is a need for improvement in this technical field.

[0009] In order to effectively convert nitrogen oxides in the exhaust gas, it is desirable to know how much DEF needs to be provided. One or more exhaust gas sensors capable of measuring NOx concentration may be provided to measure the NOx concentration of the exhaust gas, and this value may be used to determine the amount of DEF required, or otherwise provide information that may be used to control one or more parameters of the engine to control the NOx concentration in the exhaust gas. Typically, the NOx sensor is located upstream of the SCR unit to measure the concentration of NOx gas in the exhaust gas, thereby controlling the amount of DEF added. Additionally or alternatively, the NOx sensor may be located downstream of the SCR catalyst to monitor the performance of the SCR catalyst. Exhaust gas sensors are susceptible to failure if they are exposed to conditions far beyond their normal operating specifications, and NOx sensors are susceptible to changes and fluctuations in exhaust gas temperature, exhaust gas pressure, and exhaust gas velocity. Changes and fluctuations in the temperature, velocity, or pressure of the exhaust gas may cause failures in the electrical components and circuits in the NOx sensor. Failure of the exhaust gas sensor may result in reduced efficiency in exhaust gas composition management, reduced engine and exhaust system performance, and may also bring additional costs associated with replacing a failed sensor and associated vehicle downtime to the user.

[0010] US20210255277 describes a method of determining whether a NOx sensor is operating properly in an exhaust gas flow, and describes how to determine whether a NOx sensor has failed. US10221746 also describes a failure device for an exhaust control device in situations where it is difficult to determine which unit within the exhaust system has failed. Although these methods can allow the determination of a failure of an exhaust component, these methods are employed after an accident has occurred and the sensor must have begun to fail or malfunction, meaning that remedial action is required.

[0011] There exists a need to provide an alternative system that overcomes one or more disadvantages of known systems, whether noted herein or elsewhere. Summary of the invention

[0012] According to a first aspect of the invention, there is provided an exhaust duct for an exhaust system of an internal combustion engine, the exhaust duct comprising: a main channel for allowing a main flow of exhaust gas to travel through the exhaust duct; a chamber configured to receive a component portion of the exhaust gas separated from the main flow of the exhaust gas; a mounting point located in the chamber for mounting an exhaust gas sensor, the chamber being configured to change the speed and / or pressure of the exhaust gas traveling through the chamber.

[0013] Exhaust sensors are susceptible to damage due to exposure to exhaust gas at high temperatures, pressures or velocities, especially when these temperatures, pressures or velocities vary in a pulsating manner. Exhaust sensors may be particularly susceptible to damage when they are exposed to high-velocity exhaust gas. Exposure to high-velocity exhaust gas reduces the accuracy of the exhaust sensor and shortens the service life of the exhaust sensor. Exhaust sensors may include ceramic elements, and exposing the ceramic elements to exhaust gas with pressure pulsations and / or thermal gradients may cause the ceramic elements to fail. Therefore, in order to protect the exhaust sensors from damage and provide them with a longer operating life, they can be set far downstream of the exhaust manifold, where the flow variability and velocity of the exhaust gas are reduced. Positioning the exhaust sensor downstream reduces the sensor's exposure to corrosive substances, such as diesel exhaust fluid (DEF) and decomposition products, such as ammonia. In addition, the exhaust sensor is positioned downstream of the catalyst unit, which additionally reduces the amplitude of the pressure pulse of the exhaust gas generated by the ignition in the cylinder of the internal combustion engine. Conventionally, the exhaust sensor is arranged to sample the mainstream of the exhaust gas in the exhaust system, and is therefore exposed to the temperature, gas velocity and pressure of the mainstream of the exhaust gas. This may result in damage to the exhaust gas sensor and shorten its operating life.

[0014] The exhaust conduit according to the present invention provides for separating aliquot of exhaust gas from the main flow of exhaust gas and delivering the aliquot of exhaust gas to a chamber separated from the main exhaust passage. The term "aliquot of exhaust gases" covers or includes a portion of exhaust gas separated from the main flow, including but not limited to a continuous exhaust gas flow separated from the main flow. The term "aliquot of exhaust gas" also covers or includes a minor flow or auxiliary flow of exhaust gas separated from the main flow. The chamber is configured to reduce one or both of the speed and pressure of the exhaust gas in the chamber, which allows the exhaust gas sensor to be positioned in the chamber and provides a less harsh environment for the sensor. This also allows the exhaust gas sensor to be positioned at a position more upstream than otherwise. In fact, the present invention allows the exhaust gas sensor to be placed downstream of the outlet of the turbocharger without the need for an intervening catalyst unit or filter unit to be provided between the outlet of the turbocharger and the exhaust gas sensor. In addition, the reading of the exhaust gas sensor (particularly the NOx sensor) may be adversely affected by the presence of a reducing agent added to the exhaust gas to reduce the NOx level. In this manner, by providing a chamber that is separated from the main flow of exhaust gas, an exhaust gas sensor disposed within the chamber is protected from the effects of the reductant that has been added to the exhaust gas. In this way, the exhaust gas sensor is able to measure the composition of the exhaust gas without the reading being affected by the presence of the reductant that has been injected into the exhaust gas. Without the protection provided by the chamber, the exhaust gas sensor, particularly the NOx sensor, may be damaged by exposure to DEF, may provide erroneous readings, and in the worst case may fail, requiring replacement of the sensor.

[0015] “The chamber is configured to change the velocity and / or pressure of exhaust gases travelling through the chamber” encompasses or includes: maintaining the velocity and / or pressure of exhaust gases travelling through the chamber, which velocity and / or pressure may be maintained above and / or below predetermined limits.

[0016] The chamber may be configured to reduce the velocity and / or pressure of exhaust gas traveling through the chamber. Reducing the velocity of the exhaust gas is advantageous because reducing the velocity of the exhaust gas reduces pressure fluctuations caused by turbulence, thereby reducing damage to the exhaust gas sensor.

[0017] The pressure and / or velocity and / or temperature of the exhaust gas traveling through the chamber may be varied by any suitable device or means. For example, one or more vanes may be provided within the chamber that redirect the flow of the exhaust gas within the chamber. The dimensions of the chamber may be configured to allow the exhaust gas to expand and thereby reduce the pressure and / or velocity of the exhaust gas.

[0018] The exhaust gas sensor may be at least partially disposed in the chamber. The exhaust gas sensor may be disposed in the chamber to the extent required to allow the exhaust gas sensor to measure properties of the exhaust gas. Thus, in an embodiment, only the tip may be disposed in the chamber and the body of the sensor may be located outside the chamber.

[0019] The exhaust gas sensor may be any sensor for measuring a property of the exhaust gas. The exhaust gas sensor may be a temperature sensor, a pressure sensor, an oxygen sensor or a NOx sensor. Preferably, the exhaust gas sensor is a NOx sensor. The present invention is particularly applicable to exhaust systems in which DEF is injected into the main flow of the exhaust gas. The injection of DEF may result in erroneous readings if DEF or its decomposition products reach the NOx sensor.

[0020] The chamber may be at least partially arranged in a recess in the wall of the exhaust duct. In this way, the overall cross-sectional area of ​​the exhaust duct may be increased relative to the cross-sectional area immediately upstream and / or immediately downstream of the portion of the exhaust duct that includes the chamber. This allows a component portion of the exhaust gas provided to the chamber to expand and thereby reduce its pressure and / or velocity. The chamber may be at least partially defined by the wall of the recess. Alternatively, an insert may be provided that is received in the recess. By arranging the chamber in the recess, component portions of the exhaust gas that are traveling along the wall of the exhaust duct may be separated and allowed to expand into the space of the recess.

[0021] The chamber may be at least partially defined by a wall separating the exhaust gas in the chamber from the remaining portion of the exhaust gas in the main channel of the exhaust conduit. The wall may be of any suitable shape. For example, the wall may be flat, or may be curved. The wall may define the chamber alone, or may define the chamber in combination with the wall of the recess. By separating a component portion of the exhaust gas in the chamber from the exhaust gas in the main channel, the pressure and / or velocity of the exhaust gas in the chamber may be lower than the pressure and / or velocity of the exhaust gas in the main channel. In this way, the properties of the exhaust gas in the exhaust conduit, in particular the NOx concentration, may be easily measured in the chamber without exposing the exhaust gas sensor to the mainstream of the exhaust gas. The wall may have an upstream edge. The wall may have a downstream edge. The upstream edge of the wall may extend radially inward relative to the wall of the main channel.

[0022] The chamber may be configured to return a component portion of the exhaust gas to the main flow of the exhaust gas. Since the exhaust gas is likely to be subjected to additional processing downstream, the component portion of the exhaust gas removed from the main flow for measurement may be returned to the main flow. This also allows the exhaust gas to flow continuously through the chamber so that the properties of the exhaust gas can be continuously measured.

[0023] The chamber may include an inlet opening and an outlet opening. The inlet opening may be located upstream of the outlet opening. The size of the opening may be the same or different. The shape of the opening may be the same or different. The size of the inlet and / or outlet may be selected to control the amount of exhaust gas entering the chamber and the rate at which the exhaust gas can leave the chamber. The size of the inlet is selected to provide enough exhaust gas to provide accurate readings, but to be small enough to ensure that the exhaust gas sensor disposed in the chamber will not be overloaded under maximum flow conditions, because sensors such as NOx sensors require slower flow than typical engine outlet exhaust gas flows and reduce pressure fluctuations. The inlet opening may have a dome-shaped edge. In particular, the inlet opening may be at least partially defined by a concave edge. The chamber may be at least partially defined by a concave surface extending from the concave edge of the inlet opening. The concave surface of the chamber may extend radially into the exhaust conduit by a distance measured from the wall of the exhaust conduit radially outside the concave surface and between about 3 mm and about 11 mm, preferably about 7 mm. The concave surface of the chamber can extend radially into the exhaust duct a distance measured from the wall of the exhaust duct radially outward of the concave surface and ranging from about 0.01 times the outlet guide diameter to about 0.4 times the outlet guide diameter, preferably between about 0.05 times the outlet guide diameter to about 0.15 times the outlet guide diameter, preferably about 0.1 times the outlet guide diameter.

[0024] The inlet opening is preferably located upstream of a reductant injection point. As such, the exhaust conduit may include a reductant injection point. The reductant injection point is a location where DEF may be injected into the exhaust conduit. The reductant injection point may include a reductant injector. In order to prevent DEF from interfering with the operation of exhaust gas sensors, particularly NOx sensors, it is desirable to sample the exhaust gas upstream of where DEF may be present.

[0025] The inlet opening may be separated from the reductant injection point by a distance sufficient so that, in operation, substantially no reductant provided via the reductant injection point enters the chamber. If DEF or its decomposition products (particularly ammonia) mix with the exhaust gas provided to the chamber for analysis, this may result in incorrect sensor readings. It is therefore desirable to locate the inlet of the chamber a distance far enough upstream of the point of injection of DEF that no or substantially no DEF is recirculated into the chamber.

[0026] The inlet opening may be upstream of the reductant injection point and at a distance greater than about 40 mm, greater than about 50 mm, greater than about 60 mm, greater than about 70 mm, greater than about 75 mm, greater than about 80 mm, or greater than about 90 mm from the reductant injection point.

[0027] The outlet opening may be downstream of the reductant injection point and at a distance greater than about 5 mm, greater than about 10 mm, greater than about 12 mm, greater than about 15 mm from the reductant injection point.

[0028] The distance may be the absolute distance between the closest point of the inlet opening and the reductant injection point, or may be the straight-line upstream distance between a plane perpendicular to the flow direction of the exhaust gas associated with the inlet opening and a plane perpendicular to the flow direction of the exhaust gas associated with the reductant injection point.

[0029] The exhaust system may include a turbine impeller. The turbine impeller may include an outlet guide defining an outlet guide diameter. The inlet opening may be located upstream of the reductant injection point and spaced apart from the reductant injection point along the centerline of the exhaust conduit by a distance between about 0.75 times the outlet guide diameter to about 1.25 times the outlet guide diameter. The inlet opening may be located upstream of the reductant injection point and spaced apart from the reductant injection point along the centerline of the exhaust conduit by a distance between about 0.9 times the outlet guide diameter to about 1.1 times the outlet guide diameter. The inlet opening may be located upstream of the reductant injection point and spaced apart from the reductant injection point along the centerline of the exhaust conduit by a distance of about 1.0 times the outlet guide diameter. The turbine impeller may be at least partially received in the exhaust conduit.

[0030] As used herein, the term "centerline" encompasses or includes a line defined by the centroid of a cross section of an exhaust duct along the flow direction of the exhaust gas. That is, the centerline of an exhaust duct is an imaginary line drawn along the exhaust duct that is always positioned at the geometric center of the exhaust gas flowing through the exhaust duct. Typically, although not always, when the exhaust duct is attached to a turbine, the centerline will be an extension of the turbine axis, which may deviate from the turbine axis depending on the geometry of the exhaust duct.

[0031] As used herein, the term "exducer" encompasses or includes a portion of a turbine wheel configured to discharge exhaust gas into an exhaust duct. The spacing between the inlet opening of the chamber and the outlet inducer of the turbine wheel may be measured from the most downstream portion of the tip of the blades of the turbine wheel to the most upstream portion of the inlet opening as viewed from the centerline.

[0032] The inlet opening may be substantially annular.The diameter of the inlet opening may be up to about 0.15 times the diameter of the outlet flow director, up to about 0.2 times the diameter of the outlet flow director, up to about 0.3 times the diameter of the outlet flow director, or up to about 0.35 times the diameter of the outlet flow director.

[0033] The inlet opening may be spaced apart from the outlet guide of the turbine impeller along the centerline of the exhaust duct by a distance of up to about 3 times the diameter of the outlet guide. The inlet opening may be spaced apart from the outlet guide of the turbine impeller along the centerline of the exhaust duct by a distance between about 0 times the diameter of the outlet guide to about 3 times the diameter of the outlet guide. Preferably, the inlet opening is spaced apart from the turbine impeller along the centerline by a distance greater than about 0 times the diameter of the outlet guide, because if the inlet opening is spaced apart from the outlet guide by about 0 times the diameter of the outlet guide, a relatively high inefficiency of the turbine may be observed. The inlet opening may be spaced apart from the outlet guide of the turbine impeller along the centerline of the exhaust duct by a distance between about 0.75 times to about 1.25 times the diameter of the outlet guide. The inlet opening may be spaced apart from the outlet guide of the turbine impeller along the centerline of the exhaust duct by a distance between about 0.9 times to about 1.1 times the diameter of the outlet guide. The inlet opening may be spaced apart from the outlet inducer of the turbine wheel along the centerline of the exhaust duct by a distance of about 1.0 times the outlet inducer diameter. The inlet opening may be spaced apart from the outlet inducer of the turbine wheel along the centerline of the exhaust duct by a distance of about 0.8 times the outlet inducer diameter. The inlet opening may be spaced apart from the outlet inducer of the turbine wheel along the centerline of the exhaust duct by a distance of about 0.35 times the outlet inducer diameter.

[0034] The chamber may be configured to receive a portion of the exhaust gas traveling along the inner face of the exhaust conduit. The exhaust conduit is a pipe that ultimately guides the exhaust gas from the internal combustion engine to the atmosphere. Therefore, the exhaust conduit typically includes a cylindrical wall, but other cross-sectional shapes are also possible, and the present invention does not particularly limit the cross-sectional shape of the exhaust conduit. The exhaust conduit is suitable for being attached to a turbocharger and receiving the exhaust gas leaving the turbine impeller. It is desirable to minimize the disturbance of the flow leaving the turbine impeller, and also minimize the disturbance of the downstream flow. By obtaining a component portion of the exhaust gas traveling along the inner face of the exhaust conduit, the disturbance of the flow leaving the turbine impeller can be minimized, and the disturbance of the downstream flow can also be minimized. Previously, since the exhaust gas sensor is susceptible to exhaust gas temperature and exhaust gas pressure fluctuations (pressure pulses), it was not possible to sample such a flow, and therefore the exhaust gas sensor was located downstream, where the fluctuation amplitude of the temperature and pressure was reduced, but the disadvantage was that the exhaust gas sensor could be affected by incorrect readings caused by DEF contained in the exhaust gas being measured.

[0035] The exhaust duct may be a diffuser, preferably a turbine diffuser. This is an exhaust duct suitable for connection to the turbine housing of a turbocharger or an exhaust duct integral with the turbine housing of a turbocharger. Preferably, the exhaust duct is configured to be in direct fluid communication with the turbine housing of the turbocharger. Preferably, the exhaust gas leaving the turbine housing is directly transferred to the exhaust duct without passing through any intermediate unit, such as a filter or a catalyst, but it is understood that in other embodiments, the exhaust duct may be arranged downstream of the filter or the catalyst. In this way, the exhaust duct may include an inlet for receiving exhaust gas from a turbocharger having a turbine impeller, the turbine impeller having a turbine impeller nut plane, wherein when in an assembled state, the chamber has an inlet arranged downstream of the impeller nut plane and about 20mm to about 60mm from the impeller nut plane. As described above, it is desirable to minimize disturbances to the exhaust gas flow, and this can be achieved by arranging the inlet to the chamber at about 20mm to about 60mm from the impeller nut plane. It should be understood that this is the case when the exhaust duct is in an assembled state with the turbine housing and does not necessarily mean that the inlet opening is about 20 mm to about 60 mm from one end of the exhaust duct, and the exact placement will depend on how the exhaust duct and the turbine housing are connected to each other. This distance can be easily determined by assembling the exhaust duct and the corresponding turbine housing and measuring the distance between the impeller nut plane and the inlet opening. The distance can be measured to the portion of the inlet opening that is closest to the impeller nut plane. The distance can be measured between a plane perpendicular to the flow direction of the exhaust gas associated with the upstream end of the inlet opening and the impeller nut plane.

[0036] The turbine impeller may include an outlet guide defining an outlet guide diameter. The exhaust duct defines a centerline, and the chamber may include an inlet opening, the inlet opening being spaced apart from the outlet guide of the turbine impeller by a distance of up to about 3 outlet guide diameters along the centerline of the exhaust duct. The inlet opening may be spaced apart from the outlet guide of the turbine impeller by a distance between about 0 outlet guide diameters and about 3 outlet guide diameters along the centerline of the exhaust duct. Preferably, the inlet opening is spaced apart from the turbine impeller by a distance greater than about 0 outlet guide diameters along the centerline, because if the inlet opening is spaced apart from the outlet guide by about 0 outlet guide diameters, a relatively high inefficiency of the turbine may be observed. The inlet opening may be spaced apart from the outlet guide of the turbine impeller by a distance between about 0.75 outlet guide diameters and about 1.25 outlet guide diameters along the centerline of the exhaust duct. The inlet opening may be spaced apart from the outlet guide of the turbine wheel along the centerline of the exhaust duct by a distance between about 0.9 times the outlet guide diameter and about 1.1 times the outlet guide diameter. The inlet opening may be spaced apart from the outlet guide of the turbine wheel along the centerline of the exhaust duct by a distance of about 1.0 times the outlet guide diameter. The inlet opening may be spaced apart from the outlet guide of the turbine wheel along the centerline of the exhaust duct by a distance of about 0.8 times the outlet guide diameter. The inlet opening may be spaced apart from the outlet guide of the turbine wheel along the centerline of the exhaust duct by a distance of about 0.35 times the outlet guide diameter.

[0037] The exhaust duct may be an element or component of the turbine housing. The exhaust duct may be integral with the turbine housing. The turbine housing and the exhaust duct may be a single integral component, and thus increase ease of manufacture and assembly. The turbine housing, the exhaust duct and the exhaust chamber may be a single integral structure.

[0038] The chamber may be an expansion chamber. By allowing a portion of the exhaust gas to expand in the chamber, its velocity and pressure may be reduced.

[0039] The exhaust duct may have an exhaust flow axis. The chamber may have an exhaust flow axis. The two flow axes may be substantially parallel. Although the exhaust may have a vortex component, the overall flow direction of the gas is from the upstream end to the downstream end. By making the chamber substantially parallel to the main channel of the exhaust duct, the flow of the main flow of the exhaust and the flow of the component portion of the exhaust in the chamber are substantially parallel. This can help minimize disturbances to the exhaust flow when the exhaust separates from the main flow and rejoins the main flow. The exhaust gases in the exhaust duct may rotate as they move through the exhaust duct, particularly when they have previously traveled through the turbine wheel of the turbocharger.

[0040] The chamber may include a chamber centerline. The chamber centerline extends from the centroid of the inlet opening to the centroid of the outlet opening. The chamber centerline may be tilted relative to the centerline of the exhaust duct. The chamber centerline may be tilted at an angle of about 7° relative to the centerline of the exhaust duct, however, in alternative embodiments, any suitable inclination may be used. For example, the chamber centerline may be tilted relative to the centerline of the exhaust duct. The chamber centerline may be tilted up to about ±10°, or up to about ±15°, or up to about ±20°. The relative angle between the chamber centerline and the centerline of the exhaust duct may be measured at the centroid of the inlet opening.

[0041] The chamber may be defined at least in part by a wall separating the chamber from the main channel of the exhaust conduit. The presence of the chamber, and in particular the presence of the chamber wall separating the exhaust in the chamber from the exhaust in the main channel, protects an exhaust gas sensor disposed in the chamber from the effects of a rotating gas flow. The wall may include an upstream edge, the upstream edge including a rim configured to direct the exhaust into the chamber. The rim may extend into the main channel of the exhaust conduit. The rim may be angled or inclined. The rim may be positioned radially inwardly relative to an adjacent wall of the exhaust conduit. In this way, a component portion of the exhaust gas flowing along the wall of the exhaust conduit is separated from the main flow of the exhaust gas and directed into the chamber.

[0042] The wall may be in the form of a tube having an opening configured to receive the exhaust gas sensor. As such, the chamber may be defined by a tube that is a separate component from the exhaust gas conduit. In this way, the chamber may be formed separately from the remainder of the exhaust gas conduit and subsequently assembled. In this way, chambers having different sizes may be used depending on anticipated requirements.

[0043] The exhaust duct may be a two-part exhaust duct. In this way, a part of the chamber may be defined by one part, and the remaining part of the chamber may be defined by another part. It will be appreciated that a multi-part exhaust duct is also possible. The chamber may be defined at least in part by a machined straight passage.

[0044] The wall of the exhaust duct may include a receiving element for engaging with a complementary engagement element of the insert. In an assembled form, the wall of the exhaust duct and the complementary engagement element may define the chamber. The engagement element may include a groove, and the complementary engagement element may include a protrusion configured to engage with the groove. Alternatively, the opposite configuration may be selected.

[0045] The exhaust conduit may include a chamber inlet bevel. The exhaust conduit may include a chamber outlet bevel. The exhaust conduit may include an inlet bevel and an outlet bevel. The inlet bevel and / or outlet bevel may be included to facilitate exhaust gas flow into and out of the chamber. The inlet bevel and outlet bevel may allow the exhaust gas to take a more straight path into and out of the chamber, thereby reducing turbulence.

[0046] The exhaust chamber may include a plurality of inlet openings. The chamber may include an outlet opening. The plurality of inlet openings may be annular inlet openings. The plurality of inlet openings may be distributed circumferentially around a radius of the exhaust conduit. The plurality of inlet openings may be distributed equidistantly around a circumferentially extending periphery of the exhaust conduit.

[0047] According to a second aspect of the present invention, there is provided a turbine housing comprising an exhaust duct according to the first aspect of the present invention.

[0048] According to a third aspect of the present invention, there is provided a turbocharger comprising an exhaust duct or a turbine housing according to the first aspect or the second aspect of the present invention.

[0049] According to a fourth aspect of the present invention, there is provided an internal combustion engine comprising an exhaust duct, a turbine housing or a turbocharger according to the first, second or third aspect of the present invention.

[0050] The inventions according to the second, third and fourth aspects of the present invention benefit from the advantages of the invention according to the first aspect of the present invention.

[0051] According to a fifth aspect of the present invention, there is provided a method for measuring a property of exhaust gas of an internal combustion engine, the method comprising the following steps:

[0052] a) separating a component portion of the exhaust gas from the main flow of the exhaust gas in the exhaust duct into a chamber;

[0053] b) varying the pressure and / or velocity of said exhaust gas component portions; and

[0054] c) measuring properties of the component portions of the exhaust gas.

[0055] As described above, the sensor used to measure the properties of the exhaust gas is sensitive to velocity and pressure fluctuations (pressure pulses), and therefore, by separating the component portion of the exhaust gas from the mainstream of the exhaust gas and reducing one or both of the velocity and pressure, a more suitable environment can be provided for the sensor. In addition, the properties of the exhaust gas further upstream can be measured than before. The chamber can also prevent or reduce any reductant (such as DEF) injected into the exhaust gas from interfering with the reading of the exhaust gas sensor. The chamber can also prevent or reduce other liquids and fluids from being delivered to the exhaust gas flow in the exhaust system. By way of example, in the case where the exhaust system uses a diesel oxidation catalyst (DOC) and / or a diesel particulate filter (DPF), a fluid containing hydrocarbons can be injected into the exhaust gas flow. The exhaust gas sensor may be sensitive to hydrocarbons, so the presence of hydrocarbons contacting the exhaust gas sensor reduces the sensitivity and / or accuracy of the sensor, and may even cause the sensor to malfunction. Therefore, the use of a chamber as described above can prevent or reduce liquid or gaseous hydrocarbons from contacting the exhaust gas sensor.

[0056] The term "fraction of exhaust gas" encompasses or includes a portion of exhaust gas separated from the main flow, including but not limited to a continuous exhaust gas flow separated from the main flow. The term "fraction of exhaust gas" also encompasses or includes a secondary or auxiliary flow of exhaust gas separated from the main flow.

[0057] “Changing the pressure and / or velocity of a component portion of the exhaust gas” encompasses or includes: reducing the pressure and / or velocity of a component portion of the exhaust gas.

[0058] The method may also include returning the component portion of the exhaust gas to the main flow of the exhaust gas after measuring the property of the component portion of the exhaust gas. The component portion of the exhaust gas used for measurement may be returned to the main flow so that it can be processed downstream with the rest of the exhaust gas and the exhaust gas is allowed to continue to flow through the chamber for measurement.

[0059] The component portion of the exhaust gas can be separated from the main flow of the exhaust gas traveling along the inner face of the exhaust duct. By removing the component portion of the exhaust gas from the exhaust gas traveling along the inner face of the exhaust duct, disturbances to the exhaust gas flow both upstream and downstream are minimized. In addition, the true composition of the exhaust gas can be determined.

[0060] The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance of about 40 mm to about 90 mm upstream of the reductant injection point. As described in relation to the first aspect of the invention, by taking the component portion of the exhaust gas to be measured upstream of the reductant injection point, the exhaust gas is not contaminated by the reductant or its decomposition products.

[0061] The method may include separating the component portion of the exhaust gas from the mainstream of the exhaust gas upstream of the reductant injection point and at a distance greater than about 40 mm, greater than about 50 mm, greater than about 60 mm, greater than about 70 mm, greater than about 75 mm, greater than about 80 mm, or greater than about 90 mm from the reductant injection point.

[0062] The mainstream of the gas travels through a turbine wheel. The turbine wheel may include an outlet guide defining an outlet guide diameter. The exhaust conduit may define a centerline. The method may include separating a component portion of the exhaust gas from the mainstream of the exhaust gas upstream of the reductant injection point and at a distance between about 0.75 times the outlet guide diameter and about 1.25 times the outlet guide diameter from the reductant injection point along the centerline of the exhaust conduit. The method may include separating a component portion of the exhaust gas from the mainstream of the exhaust gas upstream of the reductant injection point and at a distance between about 0.9 times the outlet guide diameter and about 1.1 times the outlet guide diameter from the reductant injection point along the centerline of the exhaust conduit. The method may include separating a component portion of the exhaust gas from the mainstream of the exhaust gas upstream of the reductant injection point and at a distance of about 1.0 times the outlet guide diameter from the reductant injection point along the centerline of the exhaust conduit. The turbine wheel may be at least partially received in the exhaust conduit.

[0063] The method may include causing a mainstream flow of the exhaust gas to travel through a turbine wheel. The turbine wheel may include an outlet guide defining an outlet guide diameter. The method may include separating a component portion of the exhaust gas from the mainstream flow of the exhaust gas at a distance of up to about 3 outlet guide diameters from the outlet guide along a centerline of the exhaust conduit. The method may include separating a component portion of the exhaust gas from the mainstream flow of the exhaust gas at a distance of between about 0 outlet guide diameters and about 3 outlet guide diameters from the outlet guide along a centerline of the exhaust conduit. Preferably, the component portion of the exhaust gas is separated from the mainstream flow at a distance greater than about 0 outlet guide diameters from the turbine impeller along the centerline, because if the inlet opening is spaced apart from the outlet guide by about 0 outlet guide diameters, a relatively high inefficiency of the turbine may be observed. The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet deflector along the centerline of the exhaust conduit between about 0.75 times the diameter of the outlet deflector and about 1.25 times the diameter of the outlet deflector. The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet deflector along the centerline of the exhaust conduit between about 0.9 times the diameter of the outlet deflector and about 1.1 times the diameter of the outlet deflector. The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet deflector along the centerline of the exhaust conduit of about 1.0 times the diameter of the outlet deflector. The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet deflector along the centerline of the exhaust conduit of about 0.8 times the diameter of the outlet deflector. The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet deflector along the centerline of the exhaust conduit of about 0.35 times the diameter of the outlet deflector. The distance may all be upstream of the reductant injection point. As described in relation to the first aspect of the invention, by taking a portion of the exhaust gas upstream of the reductant injection point, the exhaust gas is not contaminated by the reductant or its decomposition products. The turbine wheel may be at least partially received in the exhaust duct.

[0064] The internal combustion engine may include a turbocharger having a turbine wheel and a turbine wheel nut plane, wherein the method further includes separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from about 20 mm to about 60 mm from the turbine wheel nut plane.

[0065] The internal combustion engine may include a turbocharger having a turbine wheel. The turbine wheel may include an outlet guide defining an outlet guide diameter. The exhaust duct may define a centerline. The method may also include separating a component portion of the exhaust gas from a mainstream of the exhaust gas at a distance of up to about 3 outlet guide diameters from the outlet guide along the centerline of the exhaust duct. The method may include separating a component portion of the exhaust gas from a mainstream of the exhaust gas at a distance of between about 0 outlet guide diameters and about 3 outlet guide diameters from the outlet guide along the centerline of the exhaust duct. Preferably, the component portion of the exhaust gas is separated from the mainstream at a distance greater than about 0 outlet guide diameters from the turbine impeller along the centerline, because if the inlet opening is spaced apart from the outlet guide by about 0 outlet guide diameters, a relatively high inefficiency of the turbine may be observed. The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet deflector along the centerline of the exhaust conduit between about 0.75 times the diameter of the outlet deflector and about 1.25 times the diameter of the outlet deflector. The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet deflector along the centerline of the exhaust conduit between about 0.9 times the diameter of the outlet deflector and about 1.1 times the diameter of the outlet deflector. The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet deflector along the centerline of the exhaust conduit of about 1.0 times the diameter of the outlet deflector. The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet deflector along the centerline of the exhaust conduit of about 0.8 times the diameter of the outlet deflector. The method may include separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet deflector along the centerline of the exhaust conduit of about 0.35 times the diameter of the outlet deflector. Again as described in relation to the first aspect of the invention, the present invention allows exhaust gas to be measured at a location further upstream than would otherwise be possible and yet minimises disturbances to the exhaust gas flow.

[0066] Any property of the exhaust gas may be measured. For example, temperature, pressure or composition such as oxygen concentration or NOx concentration may be measured. Preferably, NOx concentration is measured. Although the invention is not necessarily limited to any particular property or sensor, the invention is particularly applicable to NOx sensors in devices that include injection of DEF into the main stream of the exhaust gas.

[0067] According to a sixth aspect of the present invention, there is provided an exhaust duct for an exhaust system of an internal combustion engine, the exhaust duct comprising a ramp and a wall, the wall at least partially surrounding an opening configured to receive an exhaust gas sensor, the ramp and the wall being configured to define a space for receiving the exhaust gas sensor and being configured to shield the exhaust gas sensor from a mainstream of exhaust gas travelling through the exhaust duct.

[0068] As described above, exhaust sensors may be damaged by high exhaust velocities and pressure fluctuations (pressure pulses). It is also desirable to arrange the exhaust sensor at a position further upstream than was previously possible. According to a sixth aspect of the invention, the present invention allows the exhaust sensor to be arranged at a position further upstream than was previously possible by arranging a ramp. The ramp deflects the exhaust gas over the exhaust sensor and thereby protects the sensor from direct interaction with the exhaust gas. The wall also protects the exhaust sensor from high exhaust velocity and / or pressure fluctuations above the operating parameters of the sensor. Even though the ramp deflects the exhaust flow, a low pressure area is still created downstream of the ramp and the wall, which allows the exhaust gas to overflow into the area of ​​the exhaust sensor where the exhaust gas can be measured. Therefore, the exhaust sensor arranged in such an exhaust duct is not affected by the direct flow of exhaust gas, but is still able to measure the properties of the exhaust gas.

[0069] The ramp may be inclined radially inward from the upstream end to the downstream end. In this way, the height of the ramp increases from the upstream end to the downstream end. This may cause the flow of the exhaust gas to be deflected radially inward.

[0070] The ramp may be continuous with the wall.

[0071] The wall may have at least one discontinuity. The discontinuity may be provided in a downstream portion of the wall. The discontinuity may be configured to allow a component portion of the exhaust gas to overflow into the space defined by the ramp and the wall. By providing a discontinuity at the downstream end of the wall, the exhaust gas is able to enter the space where the exhaust gas sensor may be located. Such gas is at a lower pressure and / or lower velocity than the mainstream of the exhaust gas.

[0072] The exhaust conduit may include an exhaust gas sensor received in the opening. Thus, the exhaust gas sensor may be disposed in a space defined by the ramp and the wall. Any suitable exhaust gas sensor may be included. Preferably, the exhaust gas sensor is a NOx sensor.

[0073] The wall and ramp may extend into the exhaust conduit to an extent equal to or greater than that of the exhaust gas sensor. As it is desirable to avoid direct exposure of the exhaust gas sensor to the exhaust gas flow within the exhaust gas conduit, it is preferred that the exhaust gas sensor is recessed relative to the ramp and wall.

[0074] The wall may be substantially conformal to the shape of the exhaust gas sensor, and in particular substantially conformal to the cross-sectional shape of the exhaust gas sensor. When the wall is substantially conformal to the shape of the exhaust gas sensor, the size of the space for receiving the exhaust gas sensor is reduced, thereby providing a tighter and thereby improved shielding for the exhaust gas sensor.

[0075] According to a seventh aspect of the invention, there is provided a turbine comprising an exhaust duct according to the sixth aspect of the invention. Optionally, the exhaust duct may be defined by a turbine outlet passage of the turbine and, in addition, by a diffuser defining at least a portion of such turbine outlet passage (i.e. such that the ramp and wall are positioned within the diffuser). In such an embodiment, the ramp and wall are positioned relatively close to the outlet of the turbine wheel of the turbine.

[0076] According to an eighth aspect of the present invention, there is provided a turbocharger comprising the turbine according to the seventh aspect of the present invention.

[0077] According to a ninth aspect of the present invention, there is provided a shield cover for an exhaust gas sensor, the shield cover being configured to substantially surround a distal end of the exhaust gas sensor.

[0078] Again, to protect the exhaust gas sensor from exhaust gas and allow the sensor to be positioned further upstream than previously possible, providing a shield substantially surrounding the distal end of the exhaust gas sensor allows the exhaust gas sensor to be positioned further upstream than previously possible.

[0079] The shield may also be configured to control an amount of exhaust gas provided to a tip of the exhaust gas sensor.

[0080] The shield may be configured to be attached to an exhaust gas sensor or to a boss configured to receive an exhaust gas sensor.

[0081] The shield may include a plurality of protrusions radially disposed around a periphery of the shield.

[0082] The shield may include a plurality of holes in a side wall of the shield. The plurality of holes may be associated with corresponding protrusions disposed radially around the periphery of the shield.

[0083] The optional and / or preferred features of each aspect of the invention described herein also apply to any other aspect of the invention. The individual features of each aspect of the invention may be combined with the features of other aspects of the invention in any combination, unless these features are incompatible with each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0085] Figure 1 is a schematic diagram of a known turbocharged diesel engine system;

[0086] Figure 2 is a longitudinal section of an exhaust duct according to the first aspect of the invention attached to a turbocharger;

[0087] Figure 3 is a transverse cross-section of an exhaust duct according to the first aspect of the invention attached to a turbocharger;

[0088] Figure 4 is a depiction of an exhaust duct according to the first aspect of the invention, viewed from the upstream end towards the downstream end;

[0089] Figure 5 is a depiction of an exhaust duct according to the first aspect of the invention, viewed from the downstream end towards the upstream end;

[0090] Figure 6 is a transverse section through an exhaust duct according to the first aspect of the invention;

[0091] Figure 7 is a longitudinal section through an exhaust duct according to the first aspect of the invention;

[0092] Figure 8 is a longitudinal section through an exhaust duct according to the first aspect of the invention, showing an exhaust gas sensor in situ;

[0093] Fig. 9 is a longitudinal section through an exhaust duct according to the first aspect of the invention;

[0094] Fig.10a and Fig.10b is a drawing of a longitudinal section through an exhaust duct and an insert according to the first aspect of the invention;

[0095] Fig.11a and Fig.11b is a drawing of an exhaust duct according to a first aspect of the present invention;

[0096] Fig.12 is a cross section of an exhaust duct according to the first aspect of the present invention;

[0097] Fig.13a , Fig.13b and Fig.13c are respectively a schematic diagram of an exhaust duct according to a sixth aspect of the invention, and a plot of the flow velocity of the exhaust gas on a ramp, and a plot of an exhaust duct comprising such a ramp;

[0098] Fig.14a and Fig.14bis a drawing of a section through a turbocharger and an associated exhaust duct including a shield according to the seventh aspect of the invention, and a drawing of a shield according to the seventh aspect of the invention;

[0099] Fig.15 is a longitudinal section of an exhaust duct according to the first aspect of the invention attached to a turbocharger;

[0100] Fig.16 is a plan cross-sectional view of a turbine according to one or more aspects of the present invention;

[0101] Fig.17 yes Fig.16 A top sectional view of a turbine;

[0102] Fig.18 It is captured through the distribution module. Fig.16 an end view of a turbine in section;

[0103] Fig.19 is intercepted through the sensing channel Fig.16 A side cross-sectional view of a turbine;

[0104] Fig. 20 is a side cross-sectional view of a turbine according to one or more aspects of the present invention;

[0105] Fig.21 It is intercepted through the distribution module and the sensing channel. Fig. 20 an end view in section of a turbine of; and

[0106] Fig. 22 It is intercepted through the distribution module Fig. 20 A side cutaway view of a turbine. DETAILED DESCRIPTION

[0107] Figure 1A schematic diagram of a turbocharged diesel engine system 2 according to the prior art is shown. The system 2 includes a diesel internal combustion engine 4, a turbocharger 6, and an exhaust aftertreatment system 8. The turbocharger 6 includes a compressor 10 and a turbine 12, which are mounted to a common turbocharger shaft 14 so that the two rotate synchronously. 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 for cleaning the intake air. The compressor 10 uses the power provided by the turbocharger shaft 14 to compress the intake air, and supplies the compressed intake air to the engine 4 through a high-pressure intake duct 18 and an 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. Inside the engine 4, an internal combustion process occurs and useful work is produced. 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 conduit 24. The turbine 12 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 through a downpipe 26. The downpipe 26 is relatively long in length, for example at least 2 meters long, such as Figure 1 Indicated by the dotted line in .

[0108] 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 (and specifically a diesel exhaust fluid (DEF)) into the decomposition chamber 28 downstream of the mixing element 30 in an area where the exhaust gas is most turbulent. The heat exchange between the exhaust gas in the decomposition chamber 28 and the DEF causes the urea contained in the DEF to decompose into a reducing agent ammonia (NH 3 ) and isocyanate (HNCO). The mixture of the reductant and the exhaust gas is then passed to a selective catalytic reducer (SCR) 34 and a diesel oxidation catalyst (DOC) 36. Finally, the exhaust gas is passed to an outlet pipe 38 and continues to a muffler (not shown) and then discharged to the atmosphere.

[0109] The focus of the present invention is to incorporate a separate chamber into the exhaust conduit, which separate chamber houses the exhaust gas sensor and is configured to reduce velocity and / or pressure fluctuations within the chamber to extend the life of the sensor and / or allow the sensor to be positioned further upstream than previously possible.

[0110] Figure 2 is a longitudinal section of an exhaust duct 101 attached to a turbocharger 102 according to the first aspect of the present invention. It should be understood that Figure 2 (and other figures) are depicted without including features of the exhaust duct 101 for context, and the specific disclosure of these figures does not necessarily limit the scope of the invention to require each depicted feature. The exhaust duct 101 includes a chamber 103, which may also be referred to as an exhaust gas sensor passage. The chamber 103 includes a chamber wall 104. The chamber wall 104 at least partially defines the chamber 103. The chamber wall 104 is configured to separate a component portion 108 of the exhaust gas from the main flow MF of the exhaust gas. The chamber wall 104 is radially embedded from the main wall 109 of the exhaust duct 101 to separate the component portion 108 of the exhaust gas to be measured from the main flow MF of the exhaust gas. The chamber 103 is configured to allow the component portion 108 of the exhaust gas to expand in the chamber 103. The chamber 103 includes a mounting point 106 for mounting an exhaust gas sensor 107. The mounting point 106 can be configured to receive and retain the exhaust gas sensor 107 by any suitable means (such as, for example, screw threads). The mounting point 106 is configured to retain an exhaust gas sensor 107 therein to allow a portion of the exhaust gas sensor 107 operable to measure a property of the exhaust gas to be exposed to any exhaust gas within the chamber 103. The chamber 103 is defined in part by a recess 110 in a main wall 109 of the exhaust gas conduit. The recess 110 provides additional space into which the component portion 108 of the exhaust gas can expand.

[0111] The exhaust conduit 101 may include a reductant injection point 111 through which a reductant may be injected by a suitable injector or dispenser. The reductant may include, but is not limited to, DEF. The chamber 103 includes an inlet opening 112 through which the exhaust gas may enter the chamber 103 and an outlet opening 113 through which the exhaust gas may leave the chamber 103 and enter the main channel 105 and rejoin the main flow MF of the exhaust gas. The inlet opening 112 is located upstream of the reductant injection point 111 so that the reductant or its breakdown products cannot enter the chamber 103 through the inlet opening 112, thereby ensuring that the reading of the exhaust gas sensor 107 in the chamber 103 is not affected by the presence of the reductant and thus provides an incorrect reading. The chamber wall 104 is used to block the reductant from entering the chamber 103. The distance d1 between the plane corresponding to the midpoint of the reducing agent injection point 111 and the plane corresponding to the inlet opening 112 is selected to prevent the reducing agent injected through the reducing agent injection point 111 from entering the chamber 103 .

[0112] The exhaust duct 101 includes a main passage 105 through which the main flow MF of the exhaust gas travels in operation. In the embodiment shown, the main passage 105 is frustoconical in shape, and the cross-sectional area of ​​the main passage 105 increases in the downstream direction. Where the exhaust duct 101 has such a frustoconical shape, the exhaust duct 101 may be referred to as a diffuser, and where the exhaust duct 101 receives exhaust gas from the turbine end of a turbocharger, the exhaust duct 101 may be referred to as a turbine diffuser. The exhaust duct 101 may be integral with the turbine housing 114, or may be a separate component (e.g., Figure 2). Where the exhaust duct 101 is a separate component, the exhaust duct 101 may have suitable means for securing the exhaust duct 101 to the turbine housing 114, such as by one or more bolts, but the invention is not particularly limited to any particular securing means. The exhaust duct 101 is constructed so that in the assembled condition the inlet opening 112 is located a specific distance d2 downstream of the impeller nut plane so that the separation of the component portion 108 of the exhaust gas does not adversely affect the exhaust gas flow leaving the turbine. As shown, the inlet opening 112 is located at one end of the turbine exhaust duct 101 because the turbine housing 114 includes its own exhaust duct portion 115, which provides the required distance d2 between the turbine impeller nut plane 116 and the inlet opening 112. In embodiments where there is no turbine housing exhaust duct portion 115 or the turbine housing exhaust duct portion 115 is too short, the inlet opening 112 of the exhaust duct 101 may be located downstream of the end of the exhaust duct 101 to provide, in the assembled state, a desired distance d2 between the inlet opening 112 and the turbine wheel nut flat surface 116. The size of the inlet opening 112 and the size of the outlet opening 113 are selected so that the exhaust gas sensor 107 is provided with sufficient exhaust gas to be able to measure the properties of the exhaust gas and the exhaust gas sensor 107 is not provided with an excessive amount of exhaust gas at peak exhaust flow rates.

[0113] In operation, the exhaust gas expands through the turbine impeller 117, thereby causing the turbine impeller 117 to rotate. The turbine impeller includes an outlet guide 117a that defines the outlet guide diameter. The turbine impeller 117 is attached to the shaft, and the shaft is attached to the compressor impeller. The rotation of the turbine impeller 117 is transmitted to the compressor impeller through a common shaft, thereby causing the compressor impeller to rotate. The rotation of the compressor impeller compresses the air, and the compressed air is supplied to the internal combustion engine. The exhaust gas leaving the turbine impeller 117 travels into the main channel 105 of the exhaust duct 101, and the component part 108 of the exhaust gas in the exhaust gas leaving the turbine impeller 117 and traveling along the wall of the exhaust duct 101 and / or the exhaust duct part 115 of the turbine housing 114 is separated and enters the chamber 103 through the inlet opening 112. The component part 108 of the exhaust gas entering the chamber 103 expands, and thereby reduces its speed and / or pressure. The pressure of the exhaust gas is not uniform and there are pressure pulses therein corresponding to the combustion cycle of the cylinder of the internal combustion engine to which the exhaust conduit 101 is attached. The expansion of the component portion 108 of the exhaust gas within the chamber 103 reduces the amplitude and gas velocity of the pressure pulses and thereby provides a more suitable environment for the exhaust gas sensor 107 within the chamber 103, thereby allowing the exhaust gas sensor 107 to be positioned further upstream than otherwise. In order to meet emission requirements, a reducing agent (which may include DEF) is injected into the main flow MF of the exhaust gas. The reducing agent is injected downstream of the inlet opening 112 of the chamber 103, and therefore no reducing agent can enter the chamber 103 to affect the reading of the exhaust gas sensor 107 (preferably a NOx sensor). The chamber wall 104 prevents the reducing agent from entering the chamber 103. The exhaust gas sensor 107 is able to measure the properties of the component portion 108 of the exhaust gas. The measurement of the property can then be used to determine the operating parameters of the engine or the exhaust system. The component portion 108 of the exhaust gas is then returned to the main flow MF of the exhaust gas.

[0114] In the illustrated embodiment, the inlet opening 112 of the chamber 103 is spaced apart from the outlet deflector 117a by about 1 outlet deflector diameter along the centerline 139 of the exhaust conduit 101. In other embodiments, the inlet opening 112 may be spaced apart from the outlet deflector 117a by about 0 outlet deflector diameters to about 3 outlet deflector diameters, about 0.75 outlet deflector diameters to about 1.25 outlet deflector diameters, about 0.9 outlet deflector diameters to about 1.1 outlet deflector diameters, 0.35 outlet deflector diameters, or 0.8 outlet deflector diameters along the centerline 139.

[0115] The distance from the turbine outlet inducer 117a to the inlet opening 112 can be measured from the tip of the blades of the turbine impeller 117 to the centroid of the inlet opening 112. In some embodiments, the exhaust duct 101 may define a non-straight path including a bend. In this case, the distance from the turbine outlet inducer 117a to the inlet opening 112 can be measured along the centerline of the exhaust duct 101. The centerline is a line drawn through the centroid of the exhaust duct 112 along the main flow direction.

[0116] Figure 3 1 is a transverse cross-section of an exhaust duct 101 attached to a turbocharger. Chamber wall 104 protrudes into main passage 105 so as to transfer component portion 108 of the exhaust gas into chamber 103. The end of exhaust gas sensor 107 is disposed in chamber 103 for measuring the properties of the exhaust gas in chamber 103. An optional exhaust gas sensor shield 118 may be provided. An optional wastegate passage outlet 119 is included in the main wall of exhaust duct 109. Chamber wall 104 is depicted as being curved, but it is understood that the chamber wall may be straight. Chamber wall 104 is depicted as having rounded corners to provide a smooth transition and minimize disturbance of the exhaust gas flowing spirally along exhaust duct 101.

[0117] Figure 4 The exhaust conduit 101 is depicted as viewed from the upstream end toward the downstream end. The inlet opening 112 leading to the chamber 113 is circular in cross-section, but it is understood that the cross-sectional shape can be a shape other than circular. The chamber wall 104 protrudes into the main channel 105. The chamber wall 104 is curved in the radial direction. In other embodiments, the chamber wall 104 can be flat. In other embodiments, the chamber wall 104 can include at least one curved portion and include at least one flat portion, and the at least one curved portion can be curved in the radial direction. In other embodiments, the chamber 104 can include multiple curved portions and multiple flat portions; at least one of the multiple curved portions can be curved in the radial direction. The curved portion can include a protrusion, a dome, a protrusion, or a recess. The chamber wall 104 can be substantially flat and include a curved portion. The exhaust conduit 101 includes a reductant injector mount 122 configured to receive a reductant injector or dispenser (not shown).

[0118] Figure 5 The exhaust duct 101 is depicted viewed from the downstream end towards the upstream end. The outlet opening 113 of the chamber 103 has a different shape than the inlet opening 112 because the outlet opening 113 includes a chamber outlet bevel 121 configured to direct exhaust gas from within the chamber 103 into the main flow MF of exhaust gas within the exhaust duct 101.

[0119] Figure 6 1 is a transverse section through the exhaust duct 101, showing a circular section of the chamber 103. An optional wastegate passage 120 and a wastegate passage outlet 119 are provided, but it should be understood that these do not have to be included in the exhaust duct according to the present invention. In the case where the exhaust duct is used with a turbocharger system, an optional wastegate passage 120 and a wastegate passage outlet 119 may be provided.

[0120] Figure 7 is a further depiction of the exhaust conduit 101 showing chamber 103 , chamber 104 , as well as reductant injector mounting 122 and optional wastegate passage outlet 119 .

[0121] Figure 8 1 is another drawing of an exhaust gas conduit 101 including a chamber 103 and an exhaust gas sensor 107. The chamber wall 104 is straight in the longitudinal direction. The chamber 103 includes a chamber inlet bevel 123 and a chamber outlet bevel 121 that help guide the flow of the component portion 108 of the exhaust gas through the chamber 103.

[0122] Fig. 9 An embodiment of an exhaust duct 101 is shown in which the chamber 103 is defined by a chamber insert 124. The chamber insert 124 comprises a tube received in a corresponding recess 110 of the exhaust duct 101. In the previously described embodiments, the chamber 103 is defined by the chamber wall 104 and the wall of the recess 110, and this configuration can be produced by common machining methods, by additive manufacturing, or a combination thereof. By providing a chamber insert 124 to define the chamber 103, an appropriate chamber shape and size can be selected depending on the desired characteristics.

[0123] Fig.10a and Fig.10b 1 shows an embodiment of the exhaust duct 101 in which the chamber 103 is defined by a chamber insert 124. In this embodiment, the chamber insert 124 does not include Fig. 9103. The chamber insert 124 is not a tube with a continuous wall as in the embodiment of the present invention, but defines a portion of the chamber 103 together with the wall of the recess 110. The chamber insert 124 comprises a U-shaped component. The chamber insert 124 comprises an engagement element in the form of a protrusion 125, which extends along a portion of the length of the insert 124. The chamber wall 104 of the exhaust duct 101 comprises a groove (not shown) complementary to the protrusion 125 of the chamber insert 124. The groove is configured to receive the protrusion 125 and hold the chamber insert 124 in a desired position. The chamber insert may include side walls 126 that are parallel to each other and connected by a curved wall 127 to form a U-shaped chamber insert 124. The protrusion 125 may be orthogonal to the insert side walls 126 and extend from the end of the insert side walls 126 away from the curved wall 127 connecting the two insert side walls 126. The protrusion 125 preferably extends along a portion of the length of the chamber insert 124. The sidewall 126 includes a stepped recessed portion 128 configured to cooperate with the wall of the turbine housing 114 to provide a flow path for the exhaust gas to enter the chamber 103. It should be understood that the opposite configuration is also possible, where the chamber insert 124 includes a slot and the exhaust conduit 101 includes a complementary protrusion that engages the protrusion.

[0124] Fig.11a and Fig.11b An embodiment of an exhaust duct 101 is depicted in which the chamber 103 is defined by a sleeve 129. The sleeve 129 comprises a continuous wall that surrounds a main passage 105 of the exhaust duct 101, except for openings required for elements such as a wastegate passage outlet or a reductant injection point. The wall of the sleeve 129 comprises an inwardly extending portion 130 of a chamber wall 104 that forms the chamber 103. By providing a sleeve 129 that surrounds the main passage and has a radially inwardly extending portion 130 that defines the chamber wall 104, this allows the sleeve to be manufactured separately from the rest of the exhaust duct and may allow a different sleeve to be selected depending on specific requirements.

[0125] Fig.12 An embodiment of the exhaust duct 101 is depicted where the chamber 103 is cast or 3D printed.

[0126] Fig.13aAn embodiment of an exhaust conduit 101 including a ramp 131 is depicted. A wall 132 is provided that partially surrounds an opening 133 configured to receive an exhaust gas sensor. The wall 132 is adjacent to the ramp 131. The wall 132 may include a first section 132a and an opposing second section 132b connected by the ramp 131. The cross-section of the wall 132 is generally circular so that it conforms to the geometry of an exhaust gas sensor (not shown) that is also circular. However, in alternative embodiments, a sensor of any suitable cross-sectional shape may be used, and the wall 132 may be conformally shaped according to the shape of the sensor. The ramp 131 and the wall 132 together define a space for receiving the exhaust gas sensor. The space is generally cylindrical in shape to conform or conform to the exhaust gas sensor, and the space is substantially surrounded by the wall 132. The opening 133 leads to the space formed by the ramp 131 and the wall 132. The function of the ramp 131 and the wall 132 is to shield an exhaust gas sensor disposed within the space defined by the ramp 131 and the wall 132 from the main flow MF of the exhaust gas traveling through the exhaust duct. The wall 132 includes a discontinuity 134 in the form of a downstream gap. The discontinuity 134 allows exhaust gas that has been deflected on top of the exhaust gas sensor to overflow into the space defined by the ramp 131 and the wall 132, in which the exhaust gas sensor is disposed to allow the exhaust gas sensor to measure properties of the exhaust gas. The ramp 131 and the wall 132 are sized to extend into the exhaust duct by an amount greater than the exhaust gas sensor, so that in the assembled state, the end of the exhaust gas sensor is recessed relative to the ramp 131 and the wall 132.

[0127] Fig.13b A model flow of exhaust gas traveling over ramp 131 is depicted. Darker flows represent higher velocities and show how the highest velocity gases travel along the inner wall of the exhaust duct, and that the layer of high velocity gases is deflected by ramp 131, but a portion of the exhaust gas is able to overflow toward exhaust gas sensor 107 at a low velocity, thereby providing a more favorable environment for the exhaust gas sensor. This allows the exhaust gas sensor 107 to be positioned further upstream than would otherwise be the case.

[0128] Fig.13c An embodiment of the exhaust gas duct 101 is depicted including a ramp 131 shown from the outside of the exhaust gas duct 101. The height of the ramp 131 increases in the downstream direction in order to protect the exhaust gas sensor 107 from high velocity exhaust gases.

[0129] Fig.14a and Fig.14bAn embodiment of a shield 135 for an exhaust gas sensor 107 is depicted. The shield 135 surrounds the end of the exhaust gas sensor 107. By surrounding the end of the exhaust gas sensor 107, the shield 135 protects the end from high velocity exhaust gas traveling past. The shield 135 is configured to control the amount of exhaust gas reaching the end. Fig.14b As shown, the shield 135 includes a plurality of protrusions 136 radially disposed around the periphery of the shield 135. The shield 135 includes a plurality of holes 137 in the sidewall of the shield 135. Each protrusion 136 may have a corresponding hole 137.

[0130] Fig.15 An embodiment of an exhaust duct 101 attached to a turbocharger 102 is depicted. The exhaust duct 101 is Figure 2 The illustrated embodiment differs in that the chamber 103 includes a plurality of inlet openings 112. The plurality of inlet openings 112 are each defined by a corresponding opening in the main wall 109 of the exhaust conduit 101. Although not shown, the inlet openings 112 may include a scoop to control and / or increase the amount of the portion of the exhaust gas received by the chamber 103. The plurality of inlet openings 112 are axially aligned relative to the centerline 139 of the exhaust conduit 101. Although in Fig.15 Although not clearly visible in the figure, the chamber 103 includes a generally annular passage that extends around the periphery of the exhaust conduit 101 and provides fluid communication between all of the plurality of inlet openings 112 (for clarity, the passage is not shown in FIG. Fig.15 1. In this sense, the annular passageway functions as a manifold. The annular passageway provides fluid communication between the inlet openings 112 and a portion of the chamber 103 that is configured to receive a portion of the exhaust gas sensor 107.

[0131] When the main flow passes through the inlet opening 112, the multiple inlet openings 112 will cause disturbances to the main flow. Generally, increasing the size of the inlet opening 112 will increase the amount of the component part of the exhaust gas that can be received, but this will also increase the disturbance to the main flow. This disturbance may cause undesirable turbulence, thereby applying back pressure to the turbine 117. In the present embodiment, because the chamber 103 includes multiple inlet openings 112, the effective inlet area from which the chamber 103 can receive the component part of the exhaust gas is increased, while the size of each inlet opening 112 remains relatively small. In this way, each individual inlet opening 112 will present relatively small disturbances. In the present embodiment, the chamber 103 includes 12 inlet openings 112. However, in alternative embodiments, substantially any number of auxiliary inlet openings can be used as required.

[0132] Preferably, the inlet openings 112 are spaced substantially equally around the centerline 139 of the exhaust duct. Spacing the inlet openings 112 equally ensures that disturbances to the main flow caused by the inlet openings 112 are spaced a maximum distance from each other so that the overall disturbance is dispersed. However, in alternative embodiments, uneven spacing may be used.

[0133] Fig.16 Another embodiment of a turbine 7000 is shown. The turbine 7000 comprises a turbine housing 7002, a turbine wheel (not shown), a wastegate device 7004, a connection adapter 7006, a dosing module 7008 and a NOx sensor 7010.

[0134] The turbine housing 7002 defines a pair of inlet volutes 7012 and a turbine wheel chamber 7014. In other embodiments, the turbine housing 7002 may define a single inlet volute. Although the turbine wheel is not shown, it should be understood that during use, the turbine wheel is disposed within the turbine wheel chamber 7014, wherein the turbine wheel is supported by a shaft (not shown) for rotation about a turbine axis 7015 relative to the turbine housing 7002. Exhaust gas received from an internal combustion engine (not shown) is delivered to the turbine wheel chamber 7014 through the inlet volute 7012, and the momentum of the exhaust gas then strikes the blades of the turbine wheel, thereby generating rotation of the turbine wheel and the shaft.

[0135] The connection adapter 7006 is connected to the turbine housing 7002 so that the turbine housing 7002 and the connection adapter 7006 combine to define a portion of the turbine outlet passage 7016. The turbine outlet passage 7016 receives exhaust gas from the turbine wheel chamber 7014 that has passed through the turbine wheel. The turbine outlet passage 7016 includes a first portion 7018 and a second portion 7020, the first portion 7018 extending axially relative to the turbine axis 7015, and the second portion 7020 is angled relative to the first portion 7018 along the adapter flow axis 7021. The angular difference between the first portion 7018 and the second portion 7020 (i.e., between the turbine axis 7015 and the adapter flow axis 7021) is about 30°, but this angular difference can be changed to suit any specific packaging requirements. In some embodiments, the second portion 7020 of the turbine outlet passage 7016 can be completely axial relative to the turbine axis 7015, so that the second portion 7020 does not include any relatively angled or inclined portions.

[0136] A first portion 7018 of the turbine outlet passage 7016 is defined by the turbine housing 7002, and a second portion 7020 of the turbine outlet passage 7016 is defined by the connection adapter 7006. The second portion 7020 of the turbine outlet passage 7016 receives exhaust gas from the first portion 7018. The first portion 7018 includes a first diffuser section 7022, and the second portion 7020 includes a second diffuser section 7024. The first diffuser section 7022 and the second diffuser section 7024 are regions of the turbine housing 7002 and the connection adapter 7006, respectively, in which the flow area (i.e., the cross-sectional area relative to the flow direction) of the turbine outlet passage 7016 increases as the distance from the turbine impeller increases.

[0137] The wastegate device 7004 includes a wastegate passage 7026 extending between the turbine inlet volute 7012 and the turbine outlet passage 7016. The wastegate device 7004 also includes a pair of wastegate valves 7028, which cover corresponding valve openings (not shown) to selectively allow or prevent exhaust gas from flowing through the wastegate passage 7026. The valve openings are connected to each of the inlet volutes 7012 respectively. The wastegate valves 7028 are mounted to a common actuator (not shown) and are synchronously controlled. However, in alternative embodiments, the valves can be controlled separately. The valve openings are of approximately the same size, however, in alternative embodiments, the valve openings can be asymmetric. In addition, a single valve head can be used instead of a pair of valves 7028 to operate the valve openings. During use, when the wastegate valve 7028 is open, exhaust gas from the inlet volute 7012 is bypassed to the turbine outlet passage 7016 instead of traveling through the turbine wheel chamber 7014 and the turbine wheel.

[0138] The wastegate passage 7026 is defined in part by the connection adapter 7006. In particular, the wastegate passage 7026 is connected to the connection adapter 7006 at a wastegate passage outlet 7030. The wastegate passage outlet 7030 is defined in a sidewall 7035 of the connection adapter 7006 and is positioned approximately at the vertex of the angular bend defined between the first portion 7018 and the second section 2020 of the turbine outlet passage 7016 (i.e., approximately at the point where the adapter flow axis 7021 intersects the turbine axis 7015). The wastegate passage 7026 defines a wastegate flow axis 7032 at the wastegate passage outlet 7030. The wastegate flow axis 7032 defines the direction in which exhaust gas flows from the wastegate passage 7026 as the exhaust gas merges into the turbine outlet passage 7020. In the present embodiment, the wastegate flow axis 7032 is at an angle of approximately 45° relative to the adapter flow axis 7021. However, in alternative embodiments, substantially any angle may be used.

[0139] The connection adapter 7006 includes a mounting member 7034 for the dosing module 7008. The mounting member 7034 defines an opening 7036 in which a nozzle 7038 of the dosing module 7008 is received. The nozzle 7038 is positioned so that the nozzle 7038 is located radially outward of the sidewall 7035 of the connection adapter 7006. However, in other embodiments, the nozzle 7038 can be substantially aligned with the sidewall of the connection adapter 7006. The opening 7036 is positioned in the second diffuser section 7024. The nozzle 7038 is configured to produce a spray of aftertreatment fluid that is directed into the turbine outlet passage 7016 along a spray axis 7040. The spray axis 7040 is angled downstream at about 7° relative to the normal of the adapter axis 7021, however, in other embodiments, the spray axis 7040 can be angled at different angles to the adapter axis 7021, such as perpendicular to the adapter axis 7021. The spray of the post-treatment fluid defines a spray area 7042, in Fig.16 and Fig.18 The existence of the spray area 7042 is schematically shown by a dotted line.

[0140] The mounting 7034 and opening 7036 for the dosing module 7008 are positioned substantially on an opposite side of the turbine outlet passage 7016 from the wastegate passage outlet 7030. Furthermore, the mounting 7034 and opening 7036 for the dosing module 7008 are positioned downstream of the wastegate passage outlet 7030. The position of the wastegate passage outlet 7030 relative to the spray area 7042 and the angle of the wastegate flow axis 7032 relative to the spray area 7042 are such that during use, when the wastegate valve 7028 is open, exhaust gas that has traveled through the wastegate passage 7026 is directed into the spray area 7042 such that the exhaust gas exchanges momentum with the injected aftertreatment fluid in a flow-controlled manner.

[0141] The mounting member 7034 and the opening 7036 for the dosing module 7008 are positioned in the connection adapter 7006 and / or form a part of the connection adapter 7006. However, in alternative embodiments, the mounting member 7034 and the opening 7036 for the dosing module 7008 can be positioned in the turbine housing 7002 and / or form a part of the turbine housing 7002. Since the mounting member 7034 and the opening 7036 for the dosing module 7008 are positioned in the connection adapter 7006 or the turbine housing 7002, it means that the dosing module 7008 is positioned adjacent to the turbine impeller. Therefore, this means that the injected aftertreatment fluid can take advantage of the high exhaust temperature, which helps evaporation and decomposition. In this regard, the mounting member 7034, the opening 7036 and the dosing module 7008 are preferably positioned within a distance of no more than about 10 times the turbine impeller outlet guide diameter (preferably no more than about 5 times the outlet guide diameter, and more preferably no more than about 3 times the outlet guide diameter) downstream of the turbine impeller. In this context, the turbine wheel inducer diameter is the diameter of the inducer portion of the turbine wheel, which is approximately equal to the diameter of the narrowest portion of the first diffuser section 7022. In the illustrated embodiment, the mounting 7034, opening 7036, and distribution module 7008 are positioned downstream of the downstream end of the turbine wheel chamber (and impeller) at a distance of approximately 3.3 inducer diameters.

[0142] The connection adapter 7006 includes a sensor conduit 7044 having a sensor conduit inlet 7046 configured to receive a component portion of the exhaust gas from the turbine outlet passage 7016 and a sensor conduit outlet 7048 configured to reintroduce the exhaust gas from the sensor conduit 7044 to the turbine outlet passage 7016. The sensor conduit 7044 defines a flow area that is larger than the size of the sensor conduit inlet 7046. Therefore, the sensor conduit 7044 acts to decelerate the exhaust gas traveling through the sensor conduit. The sensor conduit includes a mounting 7050 configured to receive the NOx sensor 7010. The NOx sensor 7010 includes a sensing end 7052 that protrudes into the interior of the sensor conduit 7044. Because the geometry of the sensor conduit 7044 decelerates the exhaust gas traveling through the sensor conduit, the sensing end 7052 is exposed to exhaust gas of lower velocity, thereby reducing the risk of damaging the sensing end 7052 and improving the accuracy of the sensor readings.

[0143] It will be appreciated that because the sensor conduit 7044 decelerates the exhaust gas traveling through the sensor conduit, Figures 16 to 19 The turbine outlet passage 7016 is an exemplary embodiment of an exhaust conduit according to the first aspect of the present invention. It will be appreciated that the sensor conduit 7044 may thus have a Figures 2 to 12 103 (or exhaust gas sensor passage) of any of the Figures 104 and 105. In particular, within the meaning of the first aspect of the invention, sensor conduit 7044 may be considered to define a chamber that is configured to modify the velocity and / or pressure of exhaust gas traveling therethrough. Likewise, mounting member 7050 may be considered to define a mounting point in the chamber for mounting an exhaust gas sensor.

[0144] refer to Fig.16 , the sensor conduit inlet 7046 is positioned upstream of the opening 7036 for the dosing module 7008. Thus, the risk of aftertreatment fluid entering the sensor conduit 7044 and adversely affecting the readings taken by the NOx sensor 7010 is eliminated. The sensor conduit 7044 is part of the second diffuser section 7024. However, in alternative embodiments, the sensor conduit 7044 may be part of the first diffuser section 7022.

[0145] Fig. 20 Another embodiment of a turbine 8000 is shown. The turbine 8000 includes a turbine housing 8002, a turbine wheel (not shown), a variable geometry mechanism (not shown), a connection adapter 8006, a dosing module 8008, and a NOx sensor 8010.

[0146] The turbine housing 8002 defines an inlet volute 8012 and a turbine wheel chamber 8014. In other embodiments, the turbine housing 8002 may define more than one inlet volute 8012. Although the turbine wheel is not shown, it should be understood that during use, the turbine wheel is disposed within the turbine wheel chamber 8014, wherein the turbine wheel is supported by a shaft (not shown) for rotation about a turbine axis 8015 relative to the turbine housing 8002. Exhaust gas received from an internal combustion engine (not shown) is delivered to the turbine wheel chamber 8014 via the inlet volute 8012, and the momentum of the exhaust gas subsequently strikes the blades of the turbine wheel, thereby generating rotation of the turbine wheel and the shaft.

[0147] The connection adapter 8006 is connected to the turbine housing 8002 so that the turbine housing 8002 and the connection adapter 8006 in combination define a portion of a turbine outlet passage 8016. The turbine outlet passage 8016 receives exhaust gas from the turbine wheel chamber 8014 that has passed through the turbine wheel. The turbine outlet passage 8016 includes a first portion 8018 defined by the turbine housing 8002 and a second portion 8020 defined by the connection adapter 8006. The second portion 8020 of the turbine outlet passage 8016 receives exhaust gas from the first portion 8018. The first portion 8018 includes a first diffuser section 8022, and the second portion 8020 includes a second diffuser section 8024. The first diffuser section 8022 and the second diffuser section 8024 are regions of the turbine housing 8002 and the connection adapter 8006, respectively, in which the flow area (i.e., the cross-sectional area relative to the flow direction) of the turbine outlet passage 8016 increases with increasing distance from the turbine impeller. The first diffuser section 8022 and the second diffuser section 8024 are substantially continuous with each other, thereby defining a single continuous diffuser.

[0148] refer to Fig.21 , the connection adapter 8006 includes a mounting member 8034 for the dosing module 8008. The mounting member 8034 defines an opening 8036 in which a nozzle 8038 of the dosing module 8008 is received. The nozzle 8038 is positioned so that the nozzle 8038 is located radially outward of the sidewall 8035 of the connection adapter 8006. However, in other embodiments, the nozzle 8038 can be substantially aligned with the sidewall of the connection adapter 8006. The opening 8036 is positioned in the second diffuser section 8024. The nozzle 8038 is configured to generate a spray of the aftertreatment fluid that is directed to the turbine outlet passage 8016 along a spray axis 8040. The spray axis 8040 is angled downstream at about 7° relative to the normal to the adapter axis 8021, however, in other embodiments, the spray axis 8040 can be angled at different angles to the adapter axis 8021, such as perpendicular to the adapter axis 8021. The spray of the post-treatment fluid defines a spray area 8042, in Fig.21 The presence of the spray region 8042 is schematically shown in dashed lines in FIG. The mounting member 8034 and the opening 8036 for the dosing module 8008 are positioned within the connection adapter 8006. However, in an alternative embodiment, the mounting member 8034 and the opening 8036 for the dosing module 8008 can be positioned within the turbine housing 8002.

[0149] Since the mounting member 8034 and the opening 8036 for the distribution module 8008 are positioned in the connection adapter 8006 or the turbine housing 8002, this means that the distribution module 8008 is positioned adjacent to the turbine impeller. Therefore, this means that the injected aftertreatment fluid can take advantage of the high exhaust temperature, which helps evaporation and decomposition. In this regard, the mounting member 8034, the opening 8036 and the distribution module 8008 are preferably positioned within a distance of no more than about 10 times the turbine impeller outlet guide diameter (preferably no more than about 5 times the outlet guide diameter, and more preferably no more than about 3 times the outlet guide diameter) downstream of the turbine impeller. In this context, the turbine impeller outlet guide diameter is the diameter of the outlet guide portion of the turbine impeller, which is approximately equal to the diameter of the narrowest part of the first diffuser section 8022. In the illustrated embodiment, the mounting member 8034, the opening 8036, and the distribution module 8008 are positioned within a distance of about 1.7 times the outlet inducer diameter from the downstream end of the turbine wheel chamber 8014 and the turbine wheel. In other embodiments, the mounting member 8034, the opening 8036, and the distribution module 8008 can be positioned anywhere up to about 2 times the outlet inducer diameter from the downstream end of the turbine wheel and the turbine wheel chamber 8014, and are preferably located at least 1 times the outlet inducer diameter downstream of the downstream end of the turbine wheel and the turbine wheel chamber 8014.

[0150] The connection adapter 8006 includes a sensor conduit 8044 having a sensor conduit inlet 8046 configured to receive a component portion of the exhaust gas from the turbine outlet passage 8016 and a sensor conduit outlet 8048 configured to reintroduce the exhaust gas from the sensor conduit 8044 into the turbine outlet passage 8016. The sensor conduit inlet 8046 is angled relative to the normal of the turbine axis 8015, thereby defining a generally spoon-shaped shape relative to the flow direction. The angled profile of the sensor conduit inlet 8046 provides a larger area for fluid to enter the sensor conduit 8044 while ensuring that the profile of the sensor conduit does not protrude excessively into the turbine outlet passage 8016, which may otherwise cause an obstruction to the flow. The sensor conduit outlet 8048 is angled approximately perpendicular to the turbine axis 8015. The sensor conduit 8044 defines a larger flow area than the size of the sensor conduit inlet 8046. Thus, the sensor conduit 8044 acts to decelerate the exhaust gas traveling through the sensor conduit. The sensor conduit includes a mount 8050 configured to receive the NOx sensor 8010. The NOx sensor 8010 includes a sensing tip 8052 that protrudes into the interior of the sensor conduit 8044. Because the geometry of the sensor conduit 8044 decelerates the exhaust gas traveling through the sensor conduit, the sensing tip 8052 is exposed to lower velocity exhaust gas, thereby reducing the risk of damage to the sensing tip 8052 and improving the accuracy of the sensor readings.

[0151] It will be appreciated that because the sensor conduit 8044 decelerates the exhaust gas traveling through the sensor conduit, Figure 20 to Figure 22 The turbine outlet passage 8016 is an exemplary embodiment of an exhaust conduit according to the first aspect of the present invention. It will be appreciated that the sensor conduit 8044 may thus have a Figures 2 to 12 8044 can be considered to define a chamber that is configured to modify the velocity and / or pressure of exhaust gas traveling therethrough. Similarly, mounting member 8050 can be considered to define a mounting point in the chamber for mounting an exhaust gas sensor.

[0152] refer to Fig.21 , the sensor conduit inlet 8046 is positioned upstream of the opening 8036 for the dosing module 8008. Thus, the risk of aftertreatment fluid entering the sensor conduit 8044 and adversely affecting the readings taken by the NOx sensor 8010 is eliminated. The sensor conduit 8044 is part of the second diffuser section 8024. However, in alternative embodiments, the sensor conduit 8044 may be part of the first diffuser section 8022.

[0153] Although not shown in the illustrated embodiment, components that come into contact with the exhaust and / or reductant (e.g., DEF) may be at least partially formed of or lined with stainless steel. This is desirable because stainless steel is resistant to corrosion from byproducts formed by the injected aftertreatment fluid / reductant. It is therefore desirable that the components that are most exposed to the DEF be made of, or lined with, stainless steel.

[0154] The embodiments described in this application provide many advantages, including: 1) the ability to provide an exhaust gas sensor further upstream than would otherwise be the case; 2) the ability to inject reductant into the exhaust flow without affecting the readings of the exhaust gas sensors (particularly the NOx sensors); and 3) increased life of the exhaust gas sensors and other sensors by preventing high velocity flows from contacting the sensors.

[0155] The described and illustrated embodiments should be considered illustrative rather than restrictive, and it should be understood that only preferred embodiments are shown and described, and all changes and modifications that fall within the scope of the invention as defined by the claims are intended to be protected. With respect to the claims, it is intended that when words such as "one," "at least one," or "at least a portion" are used to define a feature, it is not intended to limit the claim to only one such feature unless the claim specifically states otherwise. When language such as "at least a portion" and / or "a portion" is used, an item may include a portion and / or the entire item unless specifically stated otherwise.

[0156] The optional and / or preferred features set forth herein may be used alone or in combination with one another where appropriate, and in particular in combination as described in the appended claims. Where appropriate, the optional and / or preferred features of each aspect of the invention set forth herein may also be applicable to any other aspect of the invention.

Claims

1. An exhaust duct for an exhaust system of an internal combustion engine, the exhaust duct comprising: a main passage for passing a main flow of exhaust gas through the exhaust conduit; a chamber configured to receive a component portion of the exhaust gas separated from the main flow of exhaust gas; A mounting point is located in the chamber for mounting an exhaust gas sensor, the chamber being configured to change a velocity and / or pressure of exhaust gas traveling through the chamber.

2. The exhaust duct according to claim 1, wherein: The chamber is configured to reduce the velocity and / or pressure of the exhaust gases traveling through the chamber.

3. The exhaust duct according to claim 1 or claim 2, wherein: An exhaust gas sensor is at least partially disposed in the chamber.

4. The exhaust duct according to claim 3, wherein: The exhaust gas sensor is a NOx sensor.

5. An exhaust duct according to any one of the preceding claims, wherein The chamber is at least partially disposed in a recess in a wall of the exhaust duct.

6. An exhaust duct according to any one of the preceding claims, wherein The chamber is at least partially defined by a wall that separates exhaust gas within the chamber from the remainder of the exhaust gas in the exhaust conduit.

7. An exhaust duct according to any one of the preceding claims, wherein The chamber is configured to return a component portion of the exhaust gas to the main flow of the exhaust gas.

8. An exhaust duct according to any one of the preceding claims, wherein The chamber includes an inlet opening and an outlet opening.

9. The exhaust duct according to claim 8, wherein: The inlet opening is arranged upstream of the reducing agent injection point.

10. The exhaust duct according to claim 9, wherein: The inlet opening is separated from the reductant injection point by a distance sufficient such that, in operation, substantially no reductant provided via the reductant injection point enters the chamber.

11. The exhaust duct according to claim 9 or 10, wherein: The exhaust system includes a turbine wheel, and the turbine wheel includes an inducer defining an inducer diameter, the exhaust conduit defining a centerline; and The inlet opening is spaced apart from the reductant injection point upstream of the reductant injection point along the centerline of the exhaust conduit by a distance between about 0.75 times the outlet deflector diameter and about 1.25 times the outlet deflector diameter.

12. An exhaust duct according to any one of the preceding claims, wherein The chamber is configured to receive a portion of the exhaust gas traveling along an inner face of the exhaust conduit.

13. An exhaust duct according to any one of the preceding claims, wherein The exhaust duct is a diffuser, optionally wherein the exhaust duct is a turbine diffuser.

14. The exhaust conduit of claim 13, the exhaust conduit comprising an inlet for receiving exhaust gas from a turbocharger having a turbine wheel, the turbine wheel including an outlet inducer defining an outlet inducer diameter, the exhaust conduit defining a centerline; and The chamber has an inlet opening that is spaced apart from the outlet inducer of the turbine wheel along the centerline of the exhaust duct by a distance of at most about 3 outlet inducer diameters.

15. An exhaust duct according to any one of the preceding claims, wherein The exhaust duct is an element of a turbine housing, optionally wherein the exhaust duct is integral with the turbine housing.

16. An exhaust duct according to any one of the preceding claims, wherein The chamber is an expansion chamber.

17. An exhaust duct according to any one of the preceding claims, wherein The chamber includes a chamber centerline extending between a centroid of the inlet opening and a centroid of the outlet opening; and Wherein the chamber centerline is inclined relative to the centerline of the exhaust conduit at an angle of up to about 20° relative to the centerline of the exhaust conduit.

18. An exhaust duct according to any one of the preceding claims, wherein The chamber is defined by a wall separating the chamber from the main passage of the exhaust conduit, wherein the wall includes an upstream edge including a rim configured to direct exhaust gas into the chamber.

19. The exhaust duct according to claim 18, wherein: The rim extends into the main passage of the exhaust conduit.

20. An exhaust duct according to claim 18 or 19, wherein: The wall is in the form of a tube having an opening configured to receive an exhaust gas sensor.

21. An exhaust duct according to claim 18 or 19, wherein: The exhaust duct is a two-part exhaust duct, optionally wherein the chamber is at least partially defined by a machined straight passage.

22. An exhaust duct according to claim 18 or 19, wherein: The wall of the exhaust duct comprises an engagement element for receiving a complementary engagement element of an insert, wherein the wall of the exhaust duct and the insert define the chamber in assembled form.

23. An exhaust duct according to claim 22, wherein: The engagement element is a slot and the complementary engagement element comprises a complementary protrusion configured to engage with the slot.

24. An exhaust duct according to any preceding claim, wherein The exhaust duct includes one or both of a chamber inlet slope and a chamber outlet slope.

25. An exhaust duct according to any preceding claim, wherein The chamber includes a plurality of inlet openings.

26. A turbine housing comprising an exhaust duct according to any preceding claim.

27. A turbocharger comprising an exhaust duct or turbine housing according to any preceding claim.

28. An internal combustion engine comprising an exhaust duct, turbine housing or turbocharger according to any preceding claim.

29. A method of measuring a property of exhaust gas of an internal combustion engine, the method comprising the steps of: a) separating a sub-portion of the exhaust gas from the main flow of the exhaust gas in the exhaust duct into a chamber; b) varying the pressure and / or velocity of a component portion of the exhaust gas; c) measuring properties of the component portions of the exhaust gas.

30. The method of claim 29, wherein: Changing the pressure and / or velocity of the component portion of the exhaust gas may include reducing the pressure and / or velocity of the component portion of the exhaust gas.

31. The method according to claim 29 or 30, wherein: The method further comprises returning the component portion of the exhaust gas to the main flow of the exhaust gas after the property of the component portion of the exhaust gas has been measured.

32. The method according to any one of claims 29 to 31, wherein: The component portion of the exhaust gas is separated from a main flow of the exhaust gas travelling along an inner surface of the exhaust gas duct.

33. The method according to any one of claims 29 to 32, wherein: The method includes passing the main flow of gas through a turbine wheel, the turbine wheel including an outlet inducer defining an outlet inducer diameter, the exhaust conduit defining a centerline, wherein the method further includes separating a component portion of the exhaust gas from the main flow of the exhaust gas upstream of the reductant injection point and at a distance from the reductant injection point along the centerline of the exhaust conduit between about 0.75 times the outlet inducer diameter and about 1.25 times the outlet inducer diameter.

34. A method according to any one of claims 29 to 33, wherein: The internal combustion engine includes a turbocharger having a turbine wheel, the turbine wheel including an outlet inducer defining an outlet inducer diameter, the exhaust conduit defining a centerline, wherein the method further includes separating the component portion of the exhaust gas from the main flow of the exhaust gas at a distance from the outlet inducer along the centerline of the exhaust conduit that is at most about 3 outlet inducer diameters.

35. The method according to any one of claims 29 to 34, wherein: The properties of the exhaust gas measured include NOx concentration.

36. An exhaust conduit for an exhaust system of an internal combustion engine, the exhaust conduit comprising a ramp and a wall, the wall at least partially surrounding an opening configured to receive an exhaust gas sensor, the ramp and the wall being configured to define a space for receiving the exhaust gas sensor and being configured to shield the exhaust gas sensor from a mainstream of exhaust gas traveling through the exhaust conduit.

37. An exhaust duct according to claim 36, wherein The ramp is inclined radially inwardly from the upstream end to the downstream end.

38. An exhaust duct according to claim 36 or 37, wherein: The ramp is continuous with the wall.

39. An exhaust duct according to any one of claims 36 to 38, wherein The wall has at least one discontinuity.

40. An exhaust duct according to claim 39, wherein: The discontinuity is provided in a downstream portion of the wall.

41. An exhaust duct according to claim 40, wherein The discontinuity is configured to allow a portion of the exhaust gas to overflow into the space defined by the ramp and the wall.

42. An exhaust duct according to any one of claims 36 to 41, wherein The exhaust conduit includes an exhaust gas sensor received in the opening.

43. An exhaust duct according to claim 42, wherein The wall and the ramp extend into the exhaust conduit to an extent that is equal to or greater than an extent that the exhaust gas sensor extends into the exhaust conduit.

44. An exhaust duct according to claim 43, wherein The wall is substantially conformal to a shape of the exhaust gas sensor.

45. A turbomachine comprising an exhaust duct according to any one of claims 36 to 44.

46. ​​A turbine according to claim 45, wherein: The turbine comprises a turbine outlet passage defining the exhaust duct, and wherein optionally the turbine outlet passage comprises a diffuser section defining the exhaust duct.

47. A shield for an exhaust gas sensor, the shield being configured to substantially surround a distal end of the exhaust gas sensor.

48. The shielding cover of claim 47, wherein: The shield is also configured to control an amount of exhaust gas provided to a tip of the exhaust gas sensor.

49. The shielding cover according to claim 47 or 48, wherein: The shield is configured to be attached to an exhaust gas sensor or to a boss configured to receive an exhaust gas sensor.

50. The shield of claim 47, 48 or 49, wherein: The shield includes a plurality of protrusions radially disposed around a periphery of the shield.

51. The shielding cover of claim 50, wherein: The shield includes a plurality of holes in a side wall of the shield.

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