WO2022129923A1

WO2022129923A1 - Turbine

Info

Publication number: WO2022129923A1
Application number: PCT/GB2021/053330
Authority: WO
Inventors: Thomas Ogilvie; Alan HAIGH; Matthew Mills
Original assignee: Cummins Ltd
Priority date: 2020-12-17
Filing date: 2021-12-16
Publication date: 2022-06-23
Also published as: GB202020039D0; DE112021006686T5; GB2602093A

Abstract

A diffuser for a turbine is disclosed. The diffuser comprises an inlet, an outlet, a diffuser wall and a reductant barrier. The inlet has a first cross-sectional area and is configured to receive fluid. The outlet is in fluid communication with the inlet, and has a second cross-sectional area, the second cross-sectional area being larger than the first cross- sectional area. The outlet is spaced apart from the inlet. The diffuser wall extends between the inlet and the outlet, and defines an inner surface and an opposing outer surface. The reductant barrier extends, at least in part, from the outer surface of the diffuser wall. The reductant barrier defines a blocking face impermeable to the passage of liquids.

Description

Turbine

The present invention relates to a diffuser, a turbine housing assembly, an adapter element, a turbine assembly, and associated methods of assembling and/or manufacturing.

Internal combustion engines, such as diesel engines, may emit carbon monoxide, hydrocarbons, particulate matter and nitrogen oxide compounds (NOX) in the exhaust. There are a number of legal requirements throughout the world which govern emission standards, and these requirements are becoming increasingly stringent, particularly in relation to nitrogen oxides (NOX) emissions. To reduce NOX emissions engine manufacturers may make use of exhaust gas recirculation and selective catalytic reduction (SCR).

Selective catalytic reduction (SCR) is an exhaust gas after-treatment, used to convert NOX into compounds that are less reactive, such as diatomic nitrogen and water, with the aid of a catalyst and a reductant. A liquid-reductant agent, such as anhydrous ammonia, aqueous ammonia, or urea, all which may be commonly referred to as Diesel Exhaust Fluid (DEF), is injected into the exhaust stream upstream of the catalyst.

In order to effectively convert the nitrogen oxides of the exhaust gas, the correct amount of DEF for given operating conditions is required, and efficient mixing of the DEF with the exhaust gas flow must also occur.

It is known to dose DEF into a turbine exhaust stream, such as into a dosing cup, to reduce NOX emissions. However, existing solutions lack the desired performance and/or longevity.

It is also known to provide a diffuser within a turbine housing and/or adapter element. However, existing diffusers can render the installation of a dosing system, like the aforementioned DEF dosing systems described above, challenging.

There exists a need to provide an alternative solution that overcomes one or more of the disadvantages of known arrangements, whether mentioned in this document or otherwise. According to a first aspect of the invention there is provided a diffuser for a turbine, the diffuser comprising: an inlet having a first cross-sectional area and being configured to receive fluid; an outlet, in fluid communication with the inlet, having a second cross-sectional area, the second cross-sectional area being larger than the first cross-sectional area, the outlet being spaced apart from the inlet; a diffuser wall, which extends between the inlet and the outlet, defining an inner surface and an opposing outer surface; and a reductant barrier which extends, at least in part, from the outer surface of the diffuser wall, the reductant barrier defining a blocking face impermeable to the passage of liquids.

The diffuser refers to a component which generally diverges in cross-section. The diffuser defines a longitudinal axis which may extend along a length of the diffuser. That longitudinal axis may extend between centre points of the inlet and outlet cross-sections of the diffuser. The longitudinal axis may also be the axis about which an upstream turbine wheel rotates. Fluid which is received from the turbine through the inlet of the diffuser may generally reduce in speed, along the length of the diffuser, as the cross- sectional area of the diffuser increases moving towards the outlet. At the same time, the static pressure of the flow may increase. The diffuser wall may be referred to as an inner wall.

The diffuser may be mounted within a turbine adapter element. The diffuser may be integrally formed with a turbine adapter element. The diffuser may be mounted within a turbine housing. The diffuser may comprise a mounting flange. The mounting flange may engage, or be configured to engage, a turbine housing.

The inlet of the diffuser may be provided at one outer end of the diffuser. The outlet of the diffuser may be provided at an opposing outer end of the diffuser. The diffuser may be a generally frustoconical body. The wall may extend continuously between the inlet and the outlet. As such, the wall may define a closed internal geometry of the diffuser between the inlet and the outlet. The inner surface may refer to an interior of the wall, whilst the outer surface may refer to an exterior of the wall. The reductant barrier may otherwise be referred to as a dam, or urea dam.

The reductant barrier may be aligned with a plane normal to the longitudinal axis. Alternatively, the reductant barrier may be angled, or inclined, relative to a plane normal to the longitudinal axis.

The reductant barrier may extend around a longitudinal axis by up to around 90°. The reductant barrier may extend around the longitudinal axis by up to around 180°. It is desirable that the reductant barrier occupy at least the lowermost position of the outer surface of the diffuser wall when the diffuser is in an installed orientation. The reductant barrier may extend around the longitudinal axis by at least around 30°, and preferably 45° or more.

The reductant barrier may have a constant thickness (in an axial direction). Alternatively, the reductant barrier may have a variable thickness (in an axial direction). The thickness may vary along an extent of the reductant barrier. The reductant barrier may have a uniform height (e.g. in a radial direction). Alternatively, the reductant barrier may have a variable height along an extent of the reductant barrier. The extent may be taken in the circumferential direction. The reductant barrier may have a greater thickness and/or height at least at a lowermost position of the reductant barrier (e.g. where liquid is most likely to pool under gravity). The reductant barrier may be said to project from the outer surface of the diffuser wall. In some arrangements, the blocking face may extend between the diffuser wall and an outer wall (of, for example, a turbine housing or adapter element).

Advantageously, the reductant barrier reduces the risk of liquid reductant contacting the (cast) turbine housing, reducing the risk that the liquid reductant corrodes the turbine housing. The reductant barrier can be said to form a seal of sorts.

Advantageously, the reductant barrier reduces the risk of reductant (and/or by-products of reductant) leaking along the diffuser wall. This alleviates corrosion issues which can occur should the liquid reductant and/or by-products flow toward the turbine and, in certain circumstances, contact the cast turbine housing of the turbine. Some reductants, such as urea, can form corrosive acids, such as isocyanic acid and cyanuric acid in use, which can be detrimental to the robustness of the materials from which the turbine housing is made. Said circumstances in which the liquid reductant may contact the turbine housing include engine shutdown and, should the diffuser be provided in a vehicle engine, when the vehicle is travelling either uphill or downhill (such that the liquid reductant flows towards the turbine, along the diffuser wall, under gravity). It will be appreciated that the nature of the mounting of the turbine, relative to the engine, will affect whether uphill or downhill travel is problematic.

Advantageously, the incorporation of the reductant barrier means that known, and corrosion-prone, materials, such as cast iron, can still be reliably incorporated in a turbine in which reductant is dosed into an exhaust gas stream.

Impermeable to the passage of liquids is intended to mean that liquids cannot flow across, or through, the blocking face. Such liquids include reductant liquid and/or byproducts, such as acids.

The diffuser is preferably manufactured from corrosion, and erosion, resistant materials (such as stainless steel).

The reductant barrier may be axially recessed relative to the outlet of the diffuser.

The reductant barrier being axially recessed relative to the outlet of the diffuser may otherwise be described as the reductant barrier being recessed relative to an axially outer face of the diffuser. Put another way, at least a portion of the diffuser projects past the reductant barrier. The recessed geometry may define a pocket, or trench, where reductant is bound between the blocking face and one or more surrounded walls.

Advantageously, recessing the reductant barrier reduces the risk of damage to the reductant barrier. Furthermore, a greater volume of reductant may be prevented from reaching the turbine housing by, for example, reductant barrier being able to block a greater volume of liquid. Recessing the reductant barrier axially relative to the outlet of the diffuser may also be advantageous for manufacturing reasons (e.g. moving the reductant barrier inboard may aid moulding and/or casting feeds).

The blocking face may be substantially planar. The blocking face being substantially plainer may otherwise be described as the blocking face being substantially flat. The blocking face maybe entirely planar.

Providing a substantially planar blocking face may advantageously improve the extent to which the blocking face is able to prevent the passage of reductant. The geometry is also readily cast, particularly where the face extends continuously between the outer surface of the diffuser wall and a mounting rim.

The outlet may be spaced apart from the inlet along a longitudinal axis, and wherein the blocking face is substantially normal to the longitudinal axis.

The blocking face being provided substantially normal to the longitudinal axis is intended to mean that the blocking face is provided substantially perpendicular to the longitudinal axis.

Advantageously, the geometry provides for improved reductant blocking functionality. Providing the blocking face normal to the axis also means the reductant barrier does not project into a downstream conduit (or other connecting pipework), and is better protected in transit. This is useful where the downstream conduit is connected, potentially by a third party, to the component in which the diffuser is provided in a subsequent assembly step.

The blocking face may be recessed relative to an axially outer portion of the reductant barrier, the reductant barrier defining a pocket.

The pocket refers to a volume, defined by the reductant barrier, in which blocked fluid reductant may be stored. This advantageously means that a greater volume of reductant can be prevented from reaching the turbine housing, even with a relatively large volume of reductant. Incorporation of the pocket reduces the risk that reductant flows around the reductant barrier.

The pocket may have a substantially constant depth in the axial direction. Alternatively, the pocket may have a variable depth in the axial direction. Preferably the depth of the pocket is greatest at a lowermost position of the reductant barrier, where liquid is most likely to pool under gravity. The variation of the pocket depth may be achieved by positioning the blocking ace, in the lowermost position, closer to the turbine wheel (e.g. moving it ‘backwards’ in the axial direction). Alternatively, the variation of pocket depth may be achieved by positioning the blocking face distal the lowermost position (e.g. at a highest position) away from the turbine wheel (e.g. moving ‘ends’ of the reductant barrier ‘forwards’).

The blocking face may be flat. The blocking face may be contoured. The reductant barrier may define a trough, which advantageously means more liquid can be collected without leaking past the reductant barrier. The reductant barrier may comprise one or more grooves.

The diffuser may comprises a plurality of projections which extend from the outer surface of the diffuser wall, and wherein the plurality of projections comprises the reductant barrier.

Advantageously, providing a plurality of projections which extend from an outer surface of the diffuser wall does not disrupt the interior of the diffuser. That is to say, the inner surface of the diffuser wall is not interrupted by the presence of the projections, which could otherwise lead to a reduction in efficiency.

The plurality of projections may define a circumferentially distributed array of projections.

Put another way, a plurality of generally circumferential projections may be provided in a circumferential distribution.

The diffuser may further comprise a mounting rim configured to engage a turbine housing element.

The mounting rim may otherwise be described as a mounting flange. Specifically, the mounting rim can be configured to engage a recess of the turbine housing element. The mounting rim may extend in an annular manner around the longitudinal axis.

Advantageously, the mounting rim provides an axial alignment feature which can be used to axially position the diffuser relative to the turbine housing. The mounting rim may define one or more openings configured to fluidly communicate with a bypass channel where the turbine is a wastegated turbine. Advantageously, the rim can therefore facilitate the mounting of the diffuser whilst still allowing passage of bypassed exhaust gas flow there passed.

The reductant barrier may extend between the outer surface of the diffuser wall and the mounting rim.

The reductant barrier extending between the outer surface of the diffuser wall and the mounting rim (optionally an adjacent portion thereof) means that the reductant barrier effectively forms a spoke, or strut, which extends between the diffuser wall and the mounting rim. Put another way, the reductant barrier connects the diffuser wall to the mounting rim.

The reductant barrier which extends between the outer surface of the diffuser wall and the mounting rim may be a solid barrier e.g. the reductant barrier may be solid across an entire radial extent between the inner and outer walls. Put another way, the blocking face may extend across a majority, or an entirety, of the reductant barrier.

The diffuser may only be attached to the inner surface of the outer wall by the reductant barrier. That is to say, the reductant barrier may be the sole means by which the diffuser is connected to the outer wall. Alternatively, the reductant barrier may be one of a number of different struts, or spokes, which connect the diffuser to the outer wall. The reductant barrier, and other struts or spokes, may be provided in a circumferentially distributed array around the longitudinal axis.

A dosing structure aperture may be provided through the diffuser wall, and wherein the reductant barrier circumferentially overlaps the dosing structure aperture.

The dosing structure refers to a component which can dose reductant into a fluid stream. For the purposes of this document, reductant may include, for example, diesel exhaust fluid (DEF) such as urea. The reductant may therefore be liquid. The reductant may flow through the dosing structure and be expelled from the dosing structure towards the inlet of the diffuser. Specifically, the reductant may be expelled towards a turbine wheel, and may be expelled towards a dosing cup which may form part of the turbine wheel. In its simplest form, the dosing structure may be a pipe through which the reductant flows and is expelled, or exits. The reductant may be actively pumped through the dosing structure, for example by a pump, or may trickle out of the dosing structure under gravity.

The dosing structure aperture may be a bore. Alternatively, the dosing structure aperture may be a slot.

The reductant barrier circumferentially overlapping the dosing structure aperture is intended to mean that, when viewed normal to the longitudinal axis, the circumferential position of the reductant barrier is at least partly shared with the circumferential position of the dosing structure aperture. Advantageously, this means that reductant is substantially prevented from flowing along the diffuser wall and through the dosing structure aperture where it may contact the turbine housing. This is particularly advantageous because there is typically a clearance between the dosing structure aperture interior and an exterior of the dosing structure. This is at least because the dosing structure may be pointed towards the turbine wheel in use, and may therefore incorporates a bend or other non-linear extent.

The reductant barrier may comprise an opening proximate the diffuser wall, the opening being configured to permit flow of bypass gas therethrough.

The reductant barrier opening may otherwise be described as a window or aperture. Advantageously, the presence of the opening permits the flow of bypass gases, from the bypass channel, there through. Advantageously, the presence of the blocking face reduces the risk that reductant can pass along the diffuser wall and corrode the turbine housing, whilst reducing the extent to which the presence of the reductant barrier affects the passage of bypass flow (and slow the efficiency of the turbine).

According to a second aspect of the invention there is provided a turbine housing assembly comprising: a turbine housing; and the diffuser according to the first aspect of the invention; wherein the diffuser is mounted to, and at least partly within, the turbine housing.

According to a third aspect of the invention there is provided an adapter element for a turbine housing, the adapter element comprising: a first connection portion configured to engage the turbine housing; a second connection portion configured to engage a conduit; an outer wall that extends between the first and second connection portions; and the diffuser according to the first aspect of the invention.

The adapter element refers to a component which is provided between a turbine and a downstream conduit. The adapter element may, for example, interpose a turbine and an exhaust manifold or pipe. The adapter element may engage a turbine housing at one end. The adapter element may engage a conduit at an opposing end.

The first and/or second connection portions facilitate the connection of the adapter element to an adjacent component. The first connection portion may be said to oppose the second connection portion in that they may each be provided at, or proximate, ends of the outer wall. The first connection portion may be configured to engage a turbine housing of the turbine. The second connection portion may be configured to engage a conduit such as a pipe and/or manifold. The connection portion may comprise a flange. The flange may be configured to be engaged by a band clamp, such as a Marman clamp. In use, the flange may be engaged by a flange of the conduit.

The adapter element may be a generally frustoconical body. In other arrangements, the adapter element may be a generally tubular body. As such, the adapter element may be said to comprise a first end and a second end. The first connection portion may be provided at the first end. The second connection portion may be provided at the second end. The outer wall may be a solid wall in that it extends continuously between the first and second connection portions. The outer wall advantageously provides a protective, or shielding, functionality in that the outer wall may be the wall that is externally exposed to contaminants and/or damage in use. Put another way, the diffuser may be shielded by the outer wall.

The diffuser being may be integrally formed with the outer wall. This may otherwise be described as the diffuser and outer wall forming a monolithic component. The diffuser and outer wall may therefore be described as being a unitary, and uniform, body. That is to say, there may be no join line between the two components. A separate process may not be required in order to connect the components. The components may be adjoined from inception. This may be achieved by an additive manufacture, or casting, process. The outlet of the diffuser may be axially recessed within an outlet of the adapter element. This may otherwise be described as the outlet of the diffuser being axially recessed relative to the adapter element outlet. Put another way, the outlet of the diffuser may be described as being both radially, and axially, within the adapter element outlet. Put another way, the adapter element outlet effectively projects past the diffuser outlet.

Advantageously, by recessing the diffuser outlet within the outer wall, and specifically the adapter element outlet, the diffuser, primarily the diffuser outlet, is protected by the outer wall. That is to say, the inner wall of the diffuser, which may be relatively thin and could otherwise be liable to become damaged in use, is protected by the outer wall from external knocks, impacts and other damage.

The reductant barrier may extend between the diffuser wall and the outer wall.

The blocking face may extend between the diffuser wall and the outer wall.

According to a fourth aspect of the invention there is provided a turbine assembly comprising: a turbine; and the diffuser according to the first aspect of the invention, the turbine housing assembly according to the second aspect of the invention, or the adapter element according to the third aspect of the invention.

The turbine may comprise a turbine wheel and a turbine housing. The turbine wheel may be generally enclosed by the turbine housing.

The adapter element may engage the turbine housing. Specifically, the first connection portion of the adapter element may engage the turbine housing. For the case of a diffuser, a diffuser may engage the turbine housing. Alternatively, the diffuser may be provided within an adapter element.

The turbine may form part of a turbocharger. Alternatively, the turbine may be a power turbine. According to a fifth aspect of the invention there is provided a turbocharger comprising: a compressor; a bearing housing; and the turbine assembly according to the fourth aspect of the invention, wherein the turbine and compressor are in power communication.

The turbocharger may be a fixed geometry turbocharger. The turbocharger may be a variable geometry turbocharger. The turbocharger may be a wastegate turbocharger.

The turbocharger may form part of an engine arrangement. The engine arrangement may be part of a vehicle, such as an automobile. The engine arrangement may have a static application, such as in a pump arrangement or in a generator.

The turbine may comprise a turbine wheel, the turbine wheel being supported on the same shaft as the compressor wheel. An exhaust gas flow may be used to drive the turbine wheel so as to drive rotation of the compressor wheel.

The compressor may be secured to the turbine via a bearing housing.

The downstream outlet of the compressor may be in fluid communication with an inlet manifold of an engine. The compressor may be used to provide a boost pressure to the engine. An engine comprising the turbocharger may provide improved performance over an engine without a turbocharger, owing to exhaust gas exhausted from the cylinders being used to drive the turbine wheel and so compressor wheel. In other words, otherwise wasted energy in the exhaust flow is used to pressurise air which is used in the combustion cycle.

A conduit forming part of an exhaust system of the engine may be connected downstream of the diffuser and/or adapter element.

According to a sixth aspect of the invention there is provided a diffuser for a turbine, the diffuser comprising: an inlet having a first cross-sectional area and being configured to receive fluid; an outlet, in fluid communication with the inlet, having a second cross-sectional area, the second cross-sectional area being larger than the first cross-sectional area, the outlet being spaced apart from the inlet; a diffuser wall, which extends between the inlet and the outlet, defining an inner surface and an opposing outer surface; a mounting rim, which extends from the diffuser wall, configured to engage a turbine housing; and a receiving feature, defined in the mounting rim, configured to receive a clamp member; or a clamp member that projects from the mounting rim, the clamp member defining: a bore configured to receive a fastener therethrough; and an engagement face configured to engage a mounting feature of a turbine housing.

The diffuser refers to a component which generally diverges in cross-section. The diffuser defines a longitudinal axis which may extend along a length of the diffuser. That longitudinal axis may extend between centre points of the inlet and outlet cross-sections of the diffuser. The longitudinal axis may also be the axis about which an upstream turbine wheel rotates. Fluid which is received from the turbine through the inlet of the diffuser may generally reduce in speed, along the length of the diffuser, as the cross- sectional area of the diffuser increases moving towards the outlet. At the same time, the static pressure of the flow may increase.

The inlet of the diffuser may be provided at one outer end of the diffuser. The outlet of the diffuser may be provided at an opposing outer end of the diffuser. The diffuser may be a generally frustoconical body. The diffuser wall may extend continuously between the inlet and the outlet. As such, the diffuser wall may define a closed internal geometry of the diffuser between the inlet and the outlet. The inner surface may refer to an interior of the diffuser wall, whilst the outer surface may refer to an exterior of the diffuser wall. The clamp member provides a convenient means of attaching the diffuser to the surrounding component (e.g. a turbine housing). The clamp member provides both an axial and rotational constraint/alignment of the diffuser. Use of the fastener extending through the bore also means that relatively high force press-fits, as is known in the art, can be avoided during the assembly process.

The fastener may be a countersunk fastener. The fastener may be a screw. The mounting feature of the turbine housing may be provided with a bore, such as a tapped bore. This may facilitate insertion of the fastener. The bore of the clamp member may be a countersunk bore.

The clamp member may otherwise be referred to as a mounting tab, or projection. The clamp member may be described as a locking member, or fixture. The clamp member may be elongate, having a relatively low thickness. The clamp member may be arcuate, having a relatively low thickness. The clamp member may comprise a gasket or other sealing member. The clamp member may be described as providing washer functionality. The clamp member may be described as a cuboidal washer.

The clamp member may be a separate component to the diffuser (e.g. a standalone part). In such instances the diffuser may comprise the receiving feature to receive at least part of the clamp member. The receiving feature may be a recess, for example. The receiving feature may locate the clamp member in an axial direction and/or in a plane normal to the longitudinal axis. The clamp member may be integrally formed with the diffuser (e.g. integral with the mounting rim). In such instances, the clamp member may project from the mounting rim.

Advantageously, the use of the clamp member provides a more accurate, and repeatable, means of positioning, and securing, the diffuser. Where the clamp member is a single point of attachment of the diffuser to the turbine housing, thermal expansion issues are mitigated because of the single attachment point (e.g. differing rates of thermal expansion can occur in use, without damaging components).

The use of the clamp member, whether a separate component or not, is particularly advantageous in a turbine housing assembly where the turbine comprises a wastegate. This is particularly because of the presence of the bypass channel, defined around an exterior of the diffuser wall.

According to a seventh aspect of the invention there is provided a turbine housing assembly comprising: the diffuser according to the sixth aspect of the invention, wherein the diffuser comprises the receiving feature; a turbine housing comprising a mounting feature; a fastener; and a clamp member, the clamp member defining: a bore configured to receive the fastener therethrough; and an engagement face configured to engage the mounting feature of a turbine housing; wherein the clamp member engages the receiving feature of the diffuser, and the mounting feature of the turbine housing, and is secured in position by the fastener, to mount the diffuser to, and at least partly within, the turbine housing.

The turbine assembly may form part of a turbine. The turbine may form part of a turbocharger. Alternatively, the turbine may be a power turbine.

The mounting feature may comprise a recess. The recess may be axial. The recess may receive the clamp member.

According to an eighth aspect of the invention there is provided turbine housing assembly comprising: the diffuser according to the sixth aspect of the invention, wherein the diffuser comprises the clamp member; a turbine housing comprising a mounting feature; and a fastener; wherein the clamp member engages the mounting feature of the turbine housing, and is secured in position by the fastener to mount the diffuser to, and at least partly within, the turbine housing.

The fastener may be received through the bore of the clamp member, and a torque communication feature of the fastener may be proximate the outlet of the diffuser. The torque communication feature may be a recess in a head of the fastener. The fastener may be a bolt. The fastener may be a machine screw. The torque communication feature may be a crosshead recess, or a flathead recess, configured to receive a respective screwdriver or other hand tool. The torque communication feature being proximate the outlet of the diffuser is intended to mean that the torque communication feature is visible, and so accessible, from the outlet of the diffuser. Advantageously, this means that the fastener can be driven by a user when the diffuser is installed in situ.

The mounting feature of the turbine housing may be a tab. The tab may otherwise be described as a projection.

According to a ninth aspect of the invention there is provided a method of assembling the turbine housing assembly according to the seventh or eighth aspects, the method comprising the steps of: i) inserting the diffuser at least partly into the turbine housing and aligning the receiving feature, or clamp member, with the mounting feature; ii) urging the engagement face of the clamp member into engagement with the mounting feature; and iii) securing the clamp member in position using the fastener.

The alignment of step i) may include axial and/or rotational alignment. The action of aligning the receiving feature, or clamp member, may be achieved by rotating the diffuser. The axial alignment of the diffuser may be facilitated by engagement of the mounting rim with a recess in the turbine housing. Engagement of the mounting rim with the recess may be described as a compression joint.

Step ii) may further comprise inserting the clamp member into the receiving feature of the diffuser (in embodiments where the clamp member is separate to the diffuser). The clamp member may be described as being received by the receiving feature.

Step iii) may comprise driving a fastener through the clamp member and into the mounting feature to affix the diffuser to the turbine housing. Where the fastener is a bolt, the fastener may be passed through the clamp member (e.g. through a bore with a diameter larger than that of the fastener), and then driven into the mounting feature.

Advantageously, the method provides a means of affixing the diffuser to the turbine housing, including axial and rotational alignment, without the use of a press-fit or similar. The process is thus simpler, and more repeatable, in comparison to prior art arrangements which use processes that require a high insertion force (and which can lead to damage to the diffuser).

According to a tenth aspect of the invention there is provided a kit of parts comprising: the diffuser according to the sixth aspect of the invention; and the turbine housing according to the seventh aspect of the invention; and optionally the clamp member of the sixth aspect of the invention.

According to an eleventh aspect of the invention there is provided a computer program comprising computer executable instructions that, when executed by a processor, cause the processor to control an additive manufacturing apparatus to manufacture the diffuser according to the first or sixth aspects of the invention, or the adapter element according to the third aspect of the invention.

According to a twelfth aspect of the invention there is provided a method of manufacturing the diffuser according to the first or sixth aspects of the invention, or the adapter element according to the third aspect of the invention, via additive manufacturing, the method comprising: obtaining an electronic file representing a geometry of the diffuser or adapter element; and controlling an additive manufacturing apparatus to manufacture, over one or more additive manufacturing steps, the diffuser or adapter element according to the geometry specified in the electronic file.

The optional and/or preferred features for each aspect of the invention set out herein are also applicable to any other aspects of the invention, where appropriate.

Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a side cross-section view of a known variable geometry turbocharger;

Figure 2 is a perspective view of part of an alternative known turbocharger that incorporates a wastegate;

Figure 3 is a perspective cutaway view of a turbine assembly, including an adapter element, according to an embodiment of the invention;

Figure 4 is a perspective view of the adapter element of Figure 3 in isolation;

Figure 5 is a cutaway side view of an adapter element, in isolation, according to another embodiment;

Figure 6 is an end view of the adapter element of Figure 5;

Figure 7a is a cutaway side view of a turbine assembly, incorporating a diffuser, in accordance with another embodiment;

Figure 7b is an end view of the turbine assembly shown in Figure 7b;

Figure 8 is an end view of a turbine assembly incorporating a diffuser according to another embodiment;

Figure 9a is a cutaway side view of a turbine housing assembly, and conduit, according to another embodiment;

Figure 9b is an end view of the turbine housing assembly of Figure 9a;

Figure 10 is an end view of the turbine housing of Figures 9a and 9b in isolation; and

Figure 11 is a magnified perspective view of part of the diffuser, and clamp member, of Figures 9a and 9b. Figure 1 is a side cross-section view of a known variable geometry turbocharger. The turbocharger comprises a (variable geometry) turbine housing 1 and a compressor housing 2 interconnected by a central bearing housing 3. A shaft 4 extends from the turbine housing 1 to the compressor housing 2 through the bearing housing 3. A turbine wheel 5 is mounted on one end of the shaft 4 for rotation within the turbine housing 1 , and a compressor wheel 6 is mounted on the other end of the shaft 4 for rotation within the compressor housing 2. The turbine wheel 5 and compressor wheel 6 are therefore in power communication with one another. The shaft 4 rotates about turbocharger axis 4a on bearing assemblies located in the bearing housing 3.

The turbine housing 1 defines an inlet volute 7 to which gas from an internal combustion engine (not shown) is delivered. The exhaust gas flows from the inlet volute 7 to an axial outlet passageway 8 via an annular inlet passageway 9 and the turbine wheel 5. The inlet passageway 9 is defined on one side by a face 10 of a radial wall of a movable annular wall member 11 , commonly referred to as a “nozzle ring”, and on the opposite side by an annular shroud 12 which forms the wall of the inlet passageway 9 facing the nozzle ring 11. The shroud 12 covers the opening of an annular recess 13 in the turbine housing 1.

The nozzle ring 11 supports an array of circumferentially and equally spaced inlet vanes 14 each of which extends across the inlet passageway 9. The vanes 14 are orientated to deflect gas flowing through the inlet passageway 9 towards the direction of rotation of the turbine wheel 5. When the nozzle ring 11 is proximate to the annular shroud 12, the vanes 14 project through suitably configured slots in the shroud 12, into the recess 13.

The position of the nozzle ring 11 is controlled by an actuator assembly of the type disclosed in US 5,868,552. An actuator (not shown) is operable to adjust the position of the nozzle ring 11 via an actuator output shaft (not shown), which is linked to a yoke 15. The yoke 15 in turn engages axially extending actuating rods 16 that support the nozzle ring 11. Accordingly, by appropriate control of the actuator (which may for instance be pneumatic or electric), the axial position of the rods 16 and thus of the nozzle ring 11 can be controlled.

The speed of the turbine wheel 5 is dependent upon the velocity of the gas passing through the annular inlet passageway 9. For a fixed rate of mass of gas flowing into the inlet passageway 9, the gas velocity is a function of the width of the inlet passageway 9, the width being adjustable by controlling the axial position of the nozzle ring 11. Figure 1 shows the annular inlet passageway 9 fully open. The inlet passageway 9 may be closed to a minimum by moving the face 10 of the nozzle ring 11 towards the shroud 12.

The nozzle ring 11 has axially extending radially inner and outer annular flanges 17 and 18 that extend into an annular cavity 19 provided in the turbine housing 1. Inner and outer sealing rings 20 and 21 are provided to seal the nozzle ring 11 with respect to inner and outer annular surfaces of the annular cavity 19 respectively, whilst allowing the nozzle ring 11 to slide within the annular cavity 19. The inner sealing ring 20 is supported within an annular groove formed in the radially inner annular surface of the cavity 19 and bears against the inner annular flange 17 of the nozzle ring 11 . The outer sealing ring 20 is supported within an annular groove formed in the radially outer annular surface of the cavity 19 and bears against the outer annular flange 18 of the nozzle ring 11.

Gas flowing from the inlet volute 7 to the outlet passageway 8 passes over the turbine wheel 5 and as a result torque is applied to the shaft 4 to drive the compressor wheel 6. Rotation of the compressor wheel 6 within the compressor housing 2 pressurises ambient air present in an air inlet 22 and delivers the pressurised air to an air outlet volute 23 from which it is fed to an internal combustion engine (not shown).

The focus of the present application is the incorporation of a diffuser downstream of the turbine wheel. This will be described and illustrated in connection with Figure 3 onwards.

Turning to Figure 2, a perspective view of an alternative known turbocharger is provided.

Like that described in connection with Figure 1 , the turbocharger of Figure 2 comprises a turbine 50 which comprises a turbine housing 52. The turbocharger further comprises a compressor 54 and bearing housing 56 (only part of which are visible in Figure 2). A primary difference between the known Figure 1 and Figure 2 arrangements is that the turbine 50, shown in Figure 2, incorporates a wastegate 58. In use, the wastegate 58 is actuated so as to divert exhaust gas around the turbine wheel 60 and thereby adjust the mass flow rate of exhaust gas which is expanded across the turbine wheel 60. This, in turn, facilitates the control of the speed (e.g. RPM) of the turbine wheel 60. When the wastegate 58 is at least partially actuated, so as to open a flow diverting channel, the overall exhaust gas flow is divided into two exhaust streams. A first stream is an exhaust stream which is expanded across the turbine wheel 60. A second stream is that of a bypass flow which has passed through the wastegate 58 (having been diverted around the turbine wheel 60).

Figure 3 is a cutaway perspective view of part of a turbine assembly 100 in accordance with an embodiment of the invention. The turbine assembly 100 comprises a turbine 102 and an adapter element 104.

The turbine 102 comprises turbine housing 106 and turbine wheel 108. Turbine wheel 108 also comprises a dosing cup 110 in the illustrated arrangement.

Considering the adapter element 104 in detail, the adapter element comprises a first end 112 and a second end 114. The adapter element 104 extends along a longitudinal axis 116. The longitudinal axis 116 is also the axis about which the turbine wheel 108 rotates. However, in other embodiments this may not be the case. An outer wall 118 extends between the first and second ends 112, 114. In the illustrated arrangement, first and second connection portions 120, 122 are provided proximate the first and second ends 112, 114. The outer wall 118 therefore also extends between the first and second connection portions 120, 122. The first and second connection portions 120, 122 take the form of flanges which engage adjacent components. The first connection portion 120 engages the turbine housing 106. The second connection portion 122 engages a conduit (not shown) through which exhaust gas flows having been expanded across the turbine wheel 108.

The adapter element 104 further comprises a diffuser 124. The diffuser 124 is generally frustoconical in that it generally diverges, in cross section, moving away from the turbine wheel 108 along the longitudinal axis 116. The diffuser 124 is integrally formed with the outer wall 118, such that the outer wall 118 and the diffuser 124 are a single body. There may be no join line between the diffuser 124 and outer wall 118.

The diffuser comprises an inlet 126 which is configured to receive fluid from the turbine 106. In the illustrated embodiment the inlet 126 takes the form of a generally circular aperture. Fluid which has been expanded across the turbine wheel 108 flows through the diffuser 124 via the inlet 126. The inlet 126 may be provided proximate the first end 112 of the adapter element 104. The inlet 126 may also be considered to be an inlet of the adapter element 104 generally.

At an end of the diffuser 124 distal the turbine 106, an outlet 128 is provided. The outlet 128 may be said to be provided proximate the second end 114 of the adapter element 104. Exhaust gas which flows into the inlet 126 of the diffuser 124 exits the diffuser 124 via the outlet 128. The inlet 126 defines a first cross-sectional area, and the outlet 128 defines a second cross-sectional area. The second cross-sectional area is greater than the first cross-sectional area. The outlet 128 is spaced apart from the inlet 126 (along the longitudinal axis 116).

The diffuser 124 further comprises a wall 130, which may be referred to as an inner wall 130, which extends between the inlet 126 and the outlet 128. The inner wall 130 defines an inner surface 130a and an outer surface 130b. The inner surface 130b is the surface proximate the fluid stream downstream of the turbine wheel 108, and the outer surface 130b is the surface proximate the outer wall 118.

The diffuser 124 further comprises a dosing structure 132. The dosing structure 132 is configured to receive, and expel, reductant. For the purposes of this document, reductant may include, for example, diesel exhaust fluid (DEF) such as urea. The reductant may therefore be liquid. The reductant facilitates Selective Catalytic Reduction (SCR) in which harmful NOx emissions are broken down into less reactive compounds.

The dosing structure 132 may be said to inject reductant, in a liquid form, into the exhaust stream downstream of the turbine wheel 108. Put another way, reductant is injected into an exhaust gas flow which has been expanded across the turbine wheel 108. Specifically, the dosing structure 132 may direct a flow of liquid reductant towards the dosing cup 110 in the turbine wheel 108. In use, when the turbine wheel 108 rotates, the dosing cup 110 may effectively atomise the liquid reductant which is then distributed axially and radially outwardly into the exhaust stream. The dosing of reductant downstream of the turbine 106 is advantageous because this is a point in the system upstream of where the SCR catalysts are located. Whilst it is known to dose reductant into a dosing cup formed in a turbine wheel, there are a number of issues with existing solutions. For example, in existing solutions a pipe may be inserted through an aperture in the turbine housing and/or diffuser. However, because of the need for the pipe to be generally angled towards the turbine wheel (e.g. L-shaped), the aperture is generally elongate. Issues can be encountered when, in some circumstances, the liquid reductant flows through the slot, on the outside of the pipe, and contacts the cast metal turbine housing. This is at least because some liquid reductant, such as urea, can form by-products in use, which can be corrosive to turbine housings. Such by-products include, for example, isocyanic acid and cyanuric acid. Cast metal turbine housings may be particularly susceptible to corrosion from such by-products, but turbine housings manufactured using other processes, and from other materials, may be similarly susceptible. The cast metal turbine housings, recited throughout this document, may be cast iron turbine housings. Turbine housings may also be comparatively expensive components, and corrosion prevention or reduction is therefore also desirable for cost reasons.

The dosing structure 132 illustrated in Figure 3 is integrally formed with at least the inner surface 130a of the inner wall 130. As such, the dosing structure 134 can be said to be integrally formed with the diffuser 124 (and the adapter element 104, more generally). Advantageously, the integrally formed nature of the dosing structure 132 and the inner wall 130 means that reductant, and/or associated by-products, is prevented from leaking through/past the inner wall 130 (of the diffuser 124) and contacting the cast metal turbine housing 106.

In the illustrated arrangement the dosing structure 132 comprises a strut 134 and a dosing outlet pipe 136. The strut 134 and dosing outlet pipe 136 may otherwise be described as first and second portions of the dosing structure 132. The strut 134 is proximate the inner wall 130 of the diffuser 124. The dosing outlet pipe 136 extends from the strut 134. In the illustrated embodiment, the dosing outlet pipe 136 further comprises a nozzle portion 138. The nozzle portion 138 may otherwise be described as an outlet portion, or an extension conduit. Although not visible in Figure 3, the dosing outlet pipe 136, specifically the nozzle portion 138 thereof, defines a fluid outlet, in the form of an aperture, through which the reductant is expelled toward the turbine wheel 108. Said aperture is visible in Figure 4, and labelled 139. In use, a stream of reductant (not shown in Figure 3) is expelled from the dosing structure 132 and impinges the dosing cup 110. The reductant stream is then atomised into the exhaust stream 148. The nozzle portion 138 advantageously projects into the dosing cup 110. The nozzle portion 138 may be omitted in other embodiments, and the portion 135 of the dosing outlet pipe 136 which is integral with the strut 134 may define the fluid outlet. The dosing outlet pipe 136 is provided at an acute angle to the longitudinal axis 116, as indicated by pipe axis 117 in Figure 3. The incline of the dosing outlet pipe 136 advantageously assists with liquid running back into the fluid outlet (i.e. not leaking from the dosing outlet pipe 136).

Although not illustrated in Figure 3, the dosing structure 132 receives reductant from an external reductant source, such as a tank. The reductant may be pumped from the external source through the dosing structure 132. Alternatively, the reductant may be fed under gravity, depending upon the orientation of the dosing structure 132.

Returning to Figure 3, the diffuser further comprises a reductant barrier 144, which is a particular focus of the present application. The reductant barrier 144 is a blocking means, or a blocking element, which reduces the risk of liquid reductant from contacting the turbine housing 106 (e.g. by passing between the outer wall 118 and the inner (diffuser) wall 130). The risk of liquid reductant contacting the cast metal turbine housing 106 is greater when the adapter element 104 forms part of an engine in a vehicle which is moving uphill or downhill (depending upon the orientation of mounting). The risk is also greater when the diffuser 124 is operating at too low a temperature. When the temperature of the diffuser 124 is not high enough, atomised reductant in the exhaust stream may condense on the inner wall 130. Said condensed reductant may collect at a lowest point of the diffuser 124, and could then flow along the inner wall 130 and (undesirably) contact the turbine housing 106. The inner wall 130 may be referred to as a diffuser wall.

The presence of the reductant barrier 144 reduces the risk that any reductant, in liquid form, which collects in the exhaust system, flows along the outer wall 118 and contacts the turbine housing 106. The reductant barrier 144 thus reduces the risk that condensed reductant and/or by-products enters the turbine in certain orientations.

In the illustrated arrangement the reductant barrier 144 is a solid projection (i.e. it does not incorporate any openings). As such, a blocking face 145 of the reductant barrier 144, which is impermeable to the passage of liquids, effectively spans the entire reductant barrier 144. The reductant barrier 144 extends between the inner surface 118a of the outer wall 118 and the outer surface 130b of the inner wall 130. The reductant barrier 144 projects from a portion of a circumference of the inner surface 118a of the outer wall 118. The reductant barrier 144 may be described as arcuate (e.g. in a plane normal to the longitudinal axis 116). In other arrangements, portions of the reductant barrier 144 may not be solid proximate the outer surface 130b of the inner wall 130 (see, for example, Figure 7b and opening 533). That is to say, the reductant barrier 144, specifically the blocking face 145 thereof, may not extend entirely from the outer surface 130b of the inner wall 130. However, the reductant barrier 144 may be solid proximate a radially outermost point, where it adjoins the adjacent surface. That is to say, the reductant barrier 144, and the blocking face 145 thereof, may extend from the outer surface 130b of the inner wall 130 to the adjacent, radially outward surface (e.g. the inner surface 118a of the outer wall 118 in this embodiment).

In the Figure 3 orientation, liquid reductant would be liable to collect at a lowermost position within the adapter element 104. It is therefore advantageous to incorporate the reductant barrier 144 at the circumferential position where reductant liquid is most likely to collect. However, this may be different for different arrangements and orientations.

Due to the reductant barrier 144 extending between the inner wall 130 and the outer wall 118, the reductant barrier 144 also provides a spoke, or strut, functionality.

The reductant barrier 144 is recessed relative to the second end 114 of the adapter element 104 to aid manufacture (and specifically moulding and/or casting feed).

A gap is provided between the inner and outer walls 130, 118. The gap is of the form of a generally annular recess 146. As suggested, the annular recess 146 extends around the longitudinal axis 116. In the illustrated embodiment, the turbine 102 is a fixed geometry turbine. As such, the turbine 102 does not incorporate a wastegate. Unlike the prior art arrangement in Figure 2, where there is a wastegate 58 and a bypass flow which joins a main exhaust flow, the Figure 3 arrangement would, in use, direct a single exhaust stream, generally labelled 148, which flows across, or through, the turbine 102. Because all of the exhaust gas flows through the diffuser 124 (i.e. as bound within the inner wall 130), the annular recess 146 does not define an active flow path per se. That is to say, no exhaust gas is actively routed through the annular recess 146. Instead, the annular recess 146 defines an air cavity which forms an insulating jacket around the diffuser 124. This is advantageous in maintaining a relatively higher temperature of the diffuser 124, by reducing the amount of heat which is transferred away from the diffuser 124. However, it will be appreciated that in other arrangements, and as will be described in connection with Figures 8a-c, an annular recess could instead define a bypass channel where the turbine in question incorporates a wastegate. The annular recess 146 is preferably at least around 5 mm, more preferably at least around 6 mm, on radius, to facilitate manufacture.

For completeness, in the illustrated arrangement the adapter element 104 engages the turbine 102 (specifically the turbine housing 106 thereof) and is secured thereto by a band clamp 152 (such as a Marman clamp). The band clamp 152 draws the first connection portion 120 (a flange in this arrangement) of the adapter element 104 towards, and into engagement with, a corresponding flange 107 of the turbine housing 106. The flanges are thereby brought into abutment with one another to secure the adapter element 104 to the turbine housing 106. A like attachment means e.g. a band clamp may be used to secure the second connection portion 122 of the adapter element 104 to a downstream conduit (not shown in Figure 3).

It is envisaged that the adapter element 104 be produced by a casting (e.g. investment casting) or additive manufacture (e.g. 3D printing, such as binder jetting) process. Such processes provide greater flexibility in terms of the geometries of features that can be incorporated in the adapter element 104.

Turning to Figure 4, the adapter element 104, of Figure 3, is shown in isolation. Figure 4 is a perspective view of the adapter element 104 from an inlet 126 end of the diffuser 124. Figure 4 is a perspective view of the adapter element 104 from an outlet 128 end of the diffuser 124.

In Figure 4, struts 154, 156, which are not visible in Figure 3, are visible. The struts 154, 156 are examples of projections which extend from an outer surface 130b of the inner wall 130. The struts 154, 156, in combination with the reductant barrier 144, support the diffuser 124 within the outer wall 118. Struts 154,156 and reductant barrier 144 are circumferentially distributed about the longitudinal axis (which is omitted from Figure 4 and 4b for clarity). It will be appreciated that, in other arrangements, the number and/or distribution of projections may be varied. The struts 154, 156 may be shaped to guide bypass flow where the adapter element 104 forms part of a wastegate turbocharger (for example). In other embodiments, struts 154, 156 may be omitted such that the reductant barrier 144 is the sole means by which the inner wall 130 is supported within the outer wall 118. Figure 4 also shows an extension portion 143 of the dosing structure 136 which extends between the inner and outer walls 130, 118. In use, reductant may flow through the extension portion 143, the strut 134 and dosing outlet pipe 136. The nozzle portion 138, of the dosing outlet pipe 136, and the fluid aperture 139 are also visible in Figure 4. The portion 135 of the dosing outlet pipe 136, which is integral with the strut 134, is also illustrated.

Figure 5 is a cutaway side view of an adapter element 300 in accordance with another embodiment. The adapter element 300 shares many features in common with the adapter element 104 previously described, and those features will therefore not be described in detail.

Like the adapter element 104 previously described, the adapter element 300 is, in use, installed between a turbine and a downstream conduit (neither of which are shown in Figure 5).

The adapter element 300 comprises a first connection portion 301 and a second connection portion 303. The first and second connection portions 301 , 303 are configured to engage a turbine and a conduit respectively. An outer wall 306 extends between the first and second connection portions 301 , 303. The connection portions 301 , 303 take the form of flanges. However, other connection portions may otherwise be incorporated. The connection portions 301 , 303 are provided at opposing ends of the outer wall 306.

Like adapter element 104, the adapter element 300 comprises an integral diffuser 304. The diffuser 304 comprises an inner wall 302. The inner wall 302 may be referred to as a diffuser wall. A dosing structure 312 is also incorporated, and is integrally formed with the inner wall 302 (and so diffuser 304 and adapter element 300 generally). Furthermore, the dosing structure 312 is also integrally formed with the outer wall 306 in this embodiment. The dosing structure 312 comprises a strut 313 and a dosing outlet pipe 315. Defined in an end of the dosing outlet pipe 315 is a fluid outlet 319. A reductant conduit 320 runs through an entirety of the dosing structure 312. It is through the reductant conduit 320 that liquid reductant is received from a reductant source (not shown) and is then expelled through the fluid outlet 319 towards the turbine wheel (not shown). The dosing structure 312 may be connected to a reductant source via a fixture 322.

The diffuser 304, and adapter element 300, comprise an inlet 316. The diffuser 304 further comprises an outlet 318. The inlet 316 defines a first cross-sectional area, and the outlet 318 defines a second cross-sectional area. The second cross-sectional area is greater than the first cross-sectional area. The outlet 318 is spaced apart from the inlet 316 along the longitudinal axis 116. The adapter element 300 further comprises outlet 320.

The adapter element 300 further comprises a plurality of projections which extend from the inner wall 302 to the outer wall 306. A first such projection is labelled 308, which is a reductant barrier. The reductant barrier 308 defines a blocking face 309, impermeable to the passage of liquids thereacross. As previously described, the reductant barrier 308, in use, reduces the risk that liquid reductant flows along the adapter element 300 and contacts a cast metal turbine housing (to which the adapter element 300 is engaged in use). The reductant barrier 308 only extends around a portion of a circumference defined by the longitudinal axis 116. That is to say, the reductant barrier 308 does not extend entirely around the adapter element 300, but instead only extends between a portion of a circumference of each of the inner and outer walls 302, 306. The reductant barrier 308 is also illustrated in Figure 6. By virtue of the reductant barrier 308, a cavity 324 is defined behind the reductant barrier 308. However, in other embodiments the cavity 324 may be filled with material (i.e. there may be no such cavity 324).

The adapter element 300 further comprises vane 314, which extends between the outer surface 302b of the inner wall 302 and the inner surface 306a of the outer wall 306.

Figure 6 is an end view of the adapter element 300 from the outlet 320 end (as shown in Figure 5). Figure 6 illustrates the reductant barrier 308 extending between inner and outer walls 302, 306 respectively. Specifically, the blocking face 309 extends between the inner and outer walls 302, 306, over a portion of a circumference of the diffuser outlet 318. The dosing structure 312 is also shown, with the strut 313 extending from the inner wall 302. The dosing outlet pipe 315 extends from the strut 313. For completeness, the vane 314 is omitted in Figure 6.

Figure 7a is a cutaway side view of part of a turbine assembly 500 according to another embodiment of the invention. The turbine assembly 500 comprises a turbine 502 (partly visible in Figure 7a) and a diffuser 504. The turbine 502 comprises a turbine housing 506 and a turbine wheel 508 (both of which are only partly visible in Figure 7a). The turbine wheel 508 comprises a dosing cup 510. The turbine wheel 508 rotates about an axis that is collinear with longitudinal axis 116. The turbine wheel 508 may therefore be said to rotate about the longitudinal axis 116.

Unlike the previous embodiments, in the present embodiment the diffuser 504 does not form part of an adapter element. Instead, in the present embodiment the diffuser 504 is directly supported by, and mounted within, the turbine housing 506. This will be described in detail below. Further distinctions of note include the dosing structure 512 being a separate assembly which is inserted through apertures in both the turbine housing 506 and the diffuser 504 (specifically through a wall 518 thereof). The dosing structure 512 comprises a strut 514 and a dosing outlet pipe 516, with a fluid outlet (not shown in Figure 7a) pointing towards, and being received within, the dosing cup 510. The separate nature of the dosing structure 512 is not a focus of the present application.

The diffuser 504 comprises an inlet 505, defining a first cross-sectional area, and a downstream outlet 507, defining a second cross-sectional area. As illustrated in Figure 7a, the second cross-sectional area is larger than the first cross-sectional area. The outlet 507 is separated from the inlet 505 along the longitudinal axis 116.

The turbine 502 is a wastegated turbine. As such, in use two exhaust flows will flow, or pass, through the turbine assembly 500: a primary, or core, exhaust flow 518, and a bypass, or secondary, flow, 520a, 520b. The flows may otherwise be described as streams, e.g. first and second streams.

The primary exhaust flow 518 flows through the diffuser 504 (having been expanded across the turbine wheel 508). The bypass flow 520a, 520b flows between the diffuser 504 and the turbine housing 506 (having been diverted around the turbine wheel 508, via a wastegate [not shown in Figure 7a]). It will be appreciated that the bypass flow is a generally annular flow field. The bypass flow 520a, 520b extends between a wall 522 of the diffuser 504 and the turbine housing 506 (specifically an outlet portion 506a of the turbine housing 506). The wall 522 may be referred to as a diffuser wall. The bypass flow 520a, 520b can be said to flow through a bypass channel 524 which is a generally annular recess, or cavity, defined between an outer surface 522b of the wall 522 of the diffuser 504 and the turbine housing 506.

A plurality of projections extend from an outer wall 522a of the wall 522. Said projections may otherwise be said to extend from the diffuser 504. Different varieties of projection will now be described in turn.

The diffuser 504 is mounted within the turbine housing 506 via a mounting flange 528, which may otherwise be described as a mounting rim. The diffuser 504, specifically the mounting flange 528 thereof, engages a recess 530 defined in the turbine housing 506 (preferably proximate an outlet end thereof). The recess 530 is an annular recess in the illustrated embodiment. The mounting flange 528 engages the turbine housing 506. The mounting flange 528 is connected to the wall 522 of the diffuser by one or more projections. The projections may comprise generally circumferential projections and/or a reductant barrier. These will be described in more detail in connection with Figures 8b onwards. The mounting flange 528 is an annular body which extends around the wall 522.

Turning to Figure 7b, an end view from an outlet end of the turbine assembly 500 (e.g. from the right hand side, looking to the left hand side, of Figure 7a) is provided. The turbine wheel 508, dosing cup 510 and dosing structure 512 are also visible in Figure 7b.

As shown in Figure 7b, the mounting flange 528 is connected to the outer surface 522b of the wall 522 by plurality of projections 532, 534, 536, (only three of which are labelled in Figure 7b). The projections 532, 534, 536 are generally circumferential projections and extend around part of a circumference about the longitudinal axis 116. Given that the projections 532, 534, 536 extend between the wall 522 and mounting flange 528, the projections 532, 534, 536 may be described as struts, spokes or supports. The projections 532, 534, 536, along with the mounting flange 528, facilitate the mounting, and alignment, of the diffuser 504 within the turbine housing 506.

Also visible in Figure 7b is a reductant barrier 539. The reductant barrier 539 comprises blocking faces 540, 541 , and projection 534 (which also defines a respective blocking face). The aforementioned blocking faces may be referred to collectively as a single blocking face.

As described above, the projection 534 extends entirely, or continuously, between the inner wall 522 and the mounting flange 528. The projection 534 can therefore be considered to attach the mounting flange 528 to the inner wall 522. The blocking faces 540, 541 project from a radially outer portion of the mounting flange 528 towards the longitudinal axis, but only extend partway across. Said blocking faces 540, 541 thus define openings 533, 535. Bypass flow, passing through bypass channel 524, exits the turbine assembly 500 via the openings 533, 535.

As previously described, the reductant barrier 540 reduces the risk that liquid reductant flows towards, and contacts, the cast metal turbine housing 506, which otherwise risks corrosion to the turbine housing 506. In this embodiment, the reductant barrier 540 does not extend entirely between the wall 522 and the mounting flange 528 along it’s circumferential extent. Instead, the reductant barrier 540, specifically blocking faces 540, 541 thereof, only extend partway between the wall 522 and the mounting flange 528, from a radially outer portion of the mounting flange 540. In other embodiments the reductant barrier 540 may extend entirely between the wall 522 and the mounting flange 528 (e.g. across the entire bypass channel 524). Advantageously, the openings 533, 535 provide a path for bypass flow to flow through, reducing the pressure drop across the mounting flange 528 (and thus reducing any reduction on turbine efficiency resulting from the presence of the reductant barrier 540).

Openings 533, 535 (only two of which are labelled in Figure 7b) may otherwise be described as being defined between the projections 532, 534, 536.

Also visible in Figure 7b is a dosing structure aperture 544. The dosing structure aperture 544 is of the form of a bore which penetrates, or extends through, the wall 522 (which may be referred to as a diffuser wall). As indicated in Figure 7b, the dosing structure aperture 544 is larger than an exterior of the dosing structure 512 (which, in the illustrated embodiment, takes the form of a pipe). It is advantageous to align the reductant barrier 540 such that it as least partly circumferentially overlaps the dosing structure aperture 544. This is to reduce the risk that reductant fluid leaks through a similar dosing structure aperture provided through the turbine housing 506. Circumferential overlap may otherwise be described as the reductant barrier 540 occupying at least part of the same angular extent, around the longitudinal axis 116, as the dosing structure aperture 544.

The blocking faces 540, 541 are substantially planar in Figure 7b. That is to say, the blocking faces 540, 541 are generally flat. Furthermore, said faces are generally normal to the longitudinal axis 116. Advantageously, the flat surfaces reduce the risk of liquid leaking past the reductant barrier 540. This is achieved whilst still allowing bypass exhaust gases to flow around the reductant barrier 540, or across the reductant barrier 540 via openings 533, 535. In the illustrated embodiment, the blocking faces 540, 541 extend in the same plane as a front face of the projection 534. That is to say, the combination of the blocking faces 540, 541 and projection 534 front face forms a continuous surface. In other embodiments, blocking faces may be provided behind, or in front of, the projection 534.

The blocking face(s) may have a constant axial extent (e.g. be located in a single plane normal to the longitudinal axis 116). Alternatively, the axial position of the blocking face(s) may vary along the extent of the blocking face(s). For example, at a lowermost point of the reductant barrier (which may be a midpoint of the reductant barrier in a plane normal to the longitudinal axis 116), the blocking face may be located axially further away from the outlet 507 than at outer ends of the reductant barrier. This may define a greater volume, in which to ‘hold’, or retain, liquid, at a lowermost point of the reductant barrier. This advantageously means more liquid can be retained in a position where liquid is most likely to gather under gravity.

Figure 8 is an end view from an outlet end of a turbine assembly 600 according to another embodiment. The turbine assembly 600 comprises the turbine 502 described in connection with Figures 8a and 8b, including the turbine housing 506 turbine wheel 508, dosing cup 510 and dosing structure 512. The turbine assembly 600 further comprises a diffuser 602 comprising a wall 604, which may be described as a diffuser wall. The diffuser 602 shares many features in common with the diffuser 504, and only the differences will be described in detail.

The diffuser 602 comprises a mounting flange 606. The mounting flange 606 engages the turbine housing 506 to mount the diffuser 602 in situ. A plurality of projections 610, 612, 614, 616 extend between the wall 604 (specifically an outer surface 604b thereof) and the mounting flange 606. As described in connection with Figures 8a and 8b, openings 618, 620, 622, 624 are defined between the projections 610, 612, 614, 616 through which bypass flow can pass.

Lowermost projection 610, as illustrated in Figure 8, is a reductant barrier 610. The reductant barrier 610 comprises a blocking face 611. The blocking face 611 effectively extends, in an arcuate manner, between projections 610a, 610b which define outer ends of the reductant barrier 610. The projections 610a, 610b also provide a blocking functionality, and can therefore be considered to define part of the blocking face 611 , or to define further respective blocking faces. The reductant barrier 610, and so the blocking face 611 , extends, in a continuous manner, between the mounting flange 606 and the outer surface 604b of the wall 606. This is advantageous for castability in that the continuously extending reductant barrier 610 can be readily cast. The blocking face 611 of the reductant barrier 610 is (axially) recessed relative to the projections 610a, 610b. Said projections 610a, 610b define axially outer faces, or portions, of the reductant barrier 610. Axially recessing the blocking face 611 can be described as defining a pocket for the collection of reductant. The recess, or pocket, advantageously provides a greater volume for ‘collecting’ liquid reductant. In other embodiments, the reductant barrier 611 may be substantially aligned with the other projections 612, 614, 616 (e.g. not recessed, and no pocket be defined).

As described in connection with Figure 7b, a dosing structure aperture 635 is provided through the diffuser wall. Advantageously, the reductant barrier 610 circumferentially overlaps the dosing structure aperture 635.

Figure 9a is a cross-section side view of part of a turbine housing assembly 700 according to another embodiment. Also visible in Figure 9a is a portion of a downstream conduit 702. The turbine housing assembly 700 comprises a diffuser 704 and a turbine housing 706. For completeness, a longitudinal axis 116 is also indicated.

The diffuser 704 shares many features in common with the diffusers previously described. The diffuser 704 comprises a diffuser wall 708, which defines inner and outer surfaces 708a, 708b. The diffuser wall 708 extends between an outlet 710 of the diffuser 704 and an inlet (not visible in Figure 9a, but would be located to the left of the indicated cut-off line 712). As is schematically indicated by a tapering portion 714 of the diffuser wall 708, the outlet 710 of the diffuser 704 defines a cross-sectional area which is greater than a cross-sectional area defined by the inlet. That is to say, the cross-sectional area defined by the diffuser wall 708 generally increases moving from the inlet to the outlet 710.

In use, exhaust gas which has been expanded across the turbine wheel (not visible in Figure 9a) flows through the diffuser 704, generally reducing in speed whilst the static pressure of the flow increases, due to the varying cross-sectional area of the interior of the diffuser 704. An example of such core, or primary, exhaust gas flow is labelled 716 in Figure 9a. Bypass exhaust gases 740 that flow through a bypass channel 742 are also indicated. The bypass channel 742 extends between the outer surface 708b of the diffuser wall 708 and the turbine housing 706 (specifically an inner surface 707 thereof).

Like other embodiments described earlier in this document, the diffuser 704 further comprises a mounting rim 718. The mounting rim 718 extends around the longitudinal axis 116 in a generally annular manner. The mounting rim 718 may otherwise be referred to as a mounting flange. In use, the mounting rim 718 is received by a corresponding recess 720 in the turbine housing 706. The recess 720 facilitates axial, and radial, alignment of the diffuser 704 within the turbine housing 706. The recess 720 extends at least partway around the longitudinal axis 116 in an annular manner.

Of particular relevance in Figure 9a is the way in which the diffuser 704 is mounted to, and partly within, the turbine housing 706. In prior art arrangements, diffusers may be press fitted into a turbine housing. However, this can create problems due to the high forces required during installation, and can also make installation of, for example, dosing systems, more difficult. Furthermore, having to press fit the diffuser into the turbine housing requires specialist equipment and it may be the case that it is preferable for the diffuser to be able to be attached to the turbine housing offsite, and potentially by another party.

The diffuser 704, as shown in Figure 9a, is mounted to the turbine housing 706 via a fixture. A clamp member 722, which engages the mounting rim 718 and the turbine housing 706, is used to facilitate the alignment of the diffuser 704 relative to the turbine housing 706, and to facilitate the attachment of the diffuser 704 to the turbine housing 706. As will be described in more detail in connection with later Figures (and as shown in a magnified view in Figure 11), the clamp member 722 comprises a bore 723 which is configured to receive a fastener 724 therethrough. In the illustrated embodiment, the bore 723 is a countersunk bore, and the fastener 724 is a countersunk bolt. It will be appreciated that variations are possible (e.g. the bore may not be countersunk, and the fastener could be a screw or similar). Also of note, in the illustrated embodiment the clamp member 722 is a separate component to both the diffuser 704 and the turbine housing 706. However, in other embodiments, the clamp member may be integrally formed with the diffuser 704.

Returning to Figure 9a, the fastener 724 is inserted through the bore 723 (of the clamp member 722) and driven into a mounting feature 726 of the turbine housing 706 (also shown in Figure 10). The mounting feature 726 comprises an (axial) recess 727 and a bore 729 (as also shown in Figure 10). The bore 729 is provided along a centreline indicator 735.

The clamp member 722 defines an engagement face 728. The engagement face 728 is configured to engage the mounting feature 726 of the turbine housing 706. Specifically, the engagement face 728 is configured to engage an end face 730 of the recess 727 of the mounting feature 726. The engagement face 728 is also configured to engage an outer face of a recess 764 defined in the mounting rim 718 of the diffuser 704 (as shown in Figure 11).

The clamp member 722 further defines an outer face 732. The outer face 732 may otherwise be described as an (axially) end face of the clamp member 722. In use, the outer face 732 of the clamp member 722 lies flush with, or recessed relative to, a surrounding, or outer, face 733 of the turbine housing 706. In the illustrated embodiment, the outer face 732 of the clamp member 722 is axially recessed relative to the outer face 733 of the turbine housing 706. A cavity 731 is thus defined between the outer faces 732, 733 of the clamp member 722 and the turbine housing 706 respectively. The outer face 732, of the clamp member 722, being flush with, or recessed relative to, the outer face 733 advantageously means that the conduit 702 can be provided in sealing engagement with the turbine housing assembly 700. The outer face 733 of the turbine housing 706 is defined in a mounting flange 736 of the turbine housing 706. Said mounting flange 736 may be referred to as a connection portion.

In use, the outer face 733 of the mounting flange 736 of the turbine housing 706 sealingly engages the sealing face 734 of a mounting flange 738 of the conduit 702. Advantageously, this reduces the risk of fluid leakage, such as the bypass exhaust gases 740 (that flow through the bypass channel 742). Furthermore, the clamp member 722 (when flush, or recessed, relative to the outer face 733 of the turbine housing 706) enables the use of an attachment means, such as a Marman clamp, to still be secured over the flanges 636, 638 of the turbine housing 606 and conduit 602 respectively, whilst still reducing or preventing fluid leakage across the surfaces.

A gasket, or other sealing member, may be provided in the cavity 723 defined between the clamp member 722 and the conduit 702 to improve the seal therebetween, and reduce leakage of fluid thereacross. Similarly, a gasket, or other sealing member, may be provided around a perimeter of the clamp member 722.

The clamp member 722 provides an advantageous means of being able to mount the diffuser 704 to, and partly within, the turbine housing 706. The use of a press fit to attach the diffuser 704 to the turbine housing 706 can be avoided owing to the clamp member 722 instead being used to secure the diffuser 704. Furthermore, because of the use of the fastener 724, the diffuser 704 can be installed without specialist equipment, off site in a different location to the rest of the installation process. This is advantageous for reasons of, for example, a third party wanting to install their own diffuser design. Further advantageously, the clamp member 722 provides both alignment and attachment functionality. The alignment is provided in both an axial direction (e.g. along longitudinal axis 116) and in a circumferential direction (e.g. rotation of the diffuser 704 around the longitudinal axis 116 can be reduced or prevented altogether). The clamp member 722 therefore provides desirable accuracy when mounting the diffuser 704 to the turbine housing 706. The clamp member 722 may be described as providing a washer-like functionality in effectively extending a retention surface, or engagement face, provided by the fastener 724.

As indicated in Figure 9a, the clamp member 722, and other features associated with the mounting of the diffuser 704, are provided at an upper position relative to the longitudinal axis 116. Put another way, the diffuser 704 is secured from a top, or 12 o’clock, position of the diffuser 704. This is advantageous because, as described earlier in this document, reductant liquid and/or byproducts may pool at a lower position under gravity. Said liquids may lead to corrosion. Offsetting/positioning the mounting components away from the region in which the liquids are likely to pool under gravity is therefore desirable for reducing the risk of said components corroding. Further, the mounting arrangement could provide a liquid leakage path, via which said liquids could contact the turbine housing, risking corrosion.

Figure 9b is an end view of the turbine housing assembly 700 from an outlet 710 end. The conduit 702 is omitted for ease of illustration.

Figure 9b shows the mounting flange 736 of the turbine housing 706, which extends around the longitudinal axis 116. The mounting rim 718 is also shown extending from the diffuser wall 708 in a generally radially outwardly direction. Provided in the mounting rim 718 are a plurality of openings 746, 748, 750, 752, 754, 756, 758, 760. The openings are configured to permit bypass gases (e.g. 740 of Figure 9a) to flow across the mounting rim 718 via the openings. The openings are therefore in fluid communication with the bypass channel 742. The bypass channel 742 extends in a generally annular manner around the longitudinal axis 116.

Figure 9b also shows the clamp member 722. As indicated in Figure 9b, the clamp member 722 projects radially outwardly beyond the mounting rim 718 (and is a separate component to the diffuser 704). The fastener 724 is also shown and, in the illustrated embodiment, is a bolt. In other embodiments, other fasteners such as screws or rivets may otherwise be used. A single fastener 724 is used in the illustrated embodiment. Advantageously, the use of a single fastener reduces the component count and means installation is faster than having further components. This is achieved whilst still being sufficient to pin, or retain, the diffuser 704 to the turbine housing 706. A head of the bolt is oriented towards the outlet 710 of the diffuser 704. A torque communication feature of the fastener 724, labelled 762 in Figure 9b, takes the form of a recess in a head of the bolt. This orientation of the torque communication feature 762 provides access for, for example, a tool, such as a crosshead or flathead screwdriver, by which the fastener 724 can be driven into the engagement feature (not shown) of the turbine housing 706.

Figure 10 is an end view of the mounting flange 736 of the turbine housing 706 in isolation. As such, Figure 10 is effectively the same as Figure 9b with all other components omitted.

With the other components omitted, the mounting feature 726 of the turbine housing 706 is visible. As described in connection with Figures 9a and 9b, the mounting feature 726 is configured to engage the engagement face 728 of the clamp member 722, and also provides material for the fastener to engage. The mounting feature 726 takes the form of a radial projection which extends towards the longitudinal axis 116, outwardly of an otherwise inner radius 737 of the mounting flange 736. The mounting feature also comprises the axial recess 727 and the bore 723. In the illustrated embodiment the mounting feature 726 is a singular projection. However, it will be appreciated that in other embodiments a plurality of such projections could otherwise be incorporated. Similarly, a plurality of clamp members, and fasteners, could be used, at different points around the longitudinal axis 116, to secure the diffuser in place. Using a plurality of clamp members/fasteners in a non-symmetric arrangement advantageously provides a rotational alignment functionality. That is to say, the diffuser 704 may only be inserted in a ‘correct’ orientation (otherwise the plurality of fasteners cannot be inserted). It will be appreciated that modifications to the size and/or location of the plurality of openings 746, 748, 750, 752, 754, 756, 758, 760 may be needed in order to accommodate a plurality of clamp members/fasteners. Save for the mounting feature 726, the face 733 of the mounting flange 736 is otherwise entirely annular. That is to say, the face 733 is defined between two concentric circles, having different diameters, in cross-section.

Figure 11 shows the clamp member 722 in more detail, along with the surrounding mounting rim 718 of the diffuser 704. The clamp member 722 is shown received in the recess 764 provided in the mounting rim 718. The recess 764 is one example of a receiving feature that is configured to receive the clamp member 722. The clamp member 722 projects radially from, or beyond, a perimeter of the mounting rim 718. The fastener 724 projects through the clamp member 722 (specifically through a bore thereof [bore not visible in Figure 11 , but labelled 723 in Figure 9a]), and a torque communication feature 762 (in the form of a hex-shaped recess) is also visible. As will be appreciated from Figure 11 , the outer face 732 of the clamp member 722 is axially recessed relative to the surrounding outer face 739 of the diffuser 704.

The clamp member 722 projects radially outwardly from within the recess 764 provided in the mounting rim 718. The recess 764 is a generally axial recess and advantageously means that the end face (732 in Figure 9a) of the clamp member 722 is flush with, or recessed relative to, the outer face 733 of the mounting flange 736 of the turbine housing 706. This provides an improved seal, across the connection between the turbine housing 706 and the conduit 702 (specifically between respective mounting flanges 736, 738 thereof). The recess 764 generally conforms to an outer geometry of the clamp member 722. The recess 764 is also an example of a receiving feature in which the clamp member 722 is at least partially received and aligned.

When the clamp member 722 is received, or seated, in the recess 764, in the diffuser 704, and the mounting feature 726 (also of the form of a recess), in the turbine housing 706, the mounting rim 718 is urged against the corresponding recess 720 in the turbine housing 706. The diffuser 704 is thus secured in position in/relative to the turbine housing 706. With the clamp member 722 secured in position (e.g. via fastener 724), the diffuser 704 cannot be disengaged from the turbine housing because of the ‘locking’ functionality of the clamp member 722 (which effectively secures the diffuser 704 to the turbine housing 706).

In use, owing to the orientation of the fastener 724, the torque communication feature 762 is accessible from an outlet end of the turbine housing assembly. As such, the fastener 724 can be driven into the turbine housing 606 with the diffuser 604 located in situ.

A method of installation will now be described in connection with Figures 9a to 11. As a first step of installation, the diffuser 704 is inserted at least partly into the turbine housing 706. That is to say, the diffuser 704 is inserted radially and, at least partially axially, within the turbine housing 706. Specifically, the diffuser 704 is inserted within the inner radius 737 of the turbine housing 706 (as shown in Figure 10). The diffuser 704 is urged, generally along the longitudinal axis 116, towards the turbine housing 706, until the mounting rim 718 engages the corresponding recess 720 in the turbine housing 706. The diffuser 704 is also circumferentially aligned (e.g. rotated) such that the recess 764 in the mounting rim 718 (see Figure 11) circumferentially overlaps the mounting feature 726 of the turbine housing 706 (see Figure 10). It will be recalled that, in the illustrated embodiment, the mounting feature 726 comprises the axial recess 727. The clamp member 722 is then placed into position across both the recess 764 in the diffuser 704 and the recess in the mounting feature 726 in the turbine housing 706. Put another way, the clamp member 722 is seated within the recesses 764, 727. In this position, the bore 723 of the clamp member 722 is generally concentric with the bore 729 in the mounting feature 726. The fastener 724 is then driven into the mounting feature 726, specifically the bore 729 thereof, by application of a torque through the torque communication feature 762 in the fastener 724. Where the fastener 724 is a bolt, the bore 729 may be threaded. Once the fastener 724 is driven into the bore 729, the clamp member 722 is secured in place. Specifically, the clamp member 722 is secured in engagement with the recess 764 (of the diffuser 704) and the recess 727 (of the turbine housing 706). The diffuser 704, specifically the mounting rim 718 thereof, is thus sandwiched between the recess 720 of the turbine housing 706 and the clamp member 722. The diffuser 704 is thus affixed to the turbine housing 706 to form the turbine housing assembly 700. Subsequent assembly steps may then include the attachment of the conduit 702 by virtue of engagement of the mounting flanges 736, 738 of the turbine housing 706 and the conduit 702 respectively.

It will be appreciated that the above process may vary slightly for arrangements where the clamp member 722 is integrally formed with the diffuser 704. For example, there is no need to insert the clamp member into the recess in the diffuser (owing to the clamp member being integral with the diffuser). Similarly, the steps may change depending upon the variety of fastener used. For example, if a rivet or pin was used, the fastener may not need to be ‘driven’ through one or more of the bores. However, the general principle of alignment of the diffuser 704 relative to the turbine housing 706, followed by securing the fastener through the clamp member, remains the same.

The aforementioned assembly process advantageously does not require the diffuser 704 to be press-fitted into the turbine housing 706. The process also only requires basic tools, such as a screwdriver or other hand tool, to drive the fastener into position. As well as providing an axial retention, the clamp member and fastener also provide a rotational constraint to secure the diffuser in position.

The engagement between the recess 720 and the mounting rim 718 may be described as a compression joint. This may provide advantageous performance from a thermal expansion perspective. The recess 764 may be machined out of the diffuser 704. The clamp member may be manufactured from stainless steel or similar.

The adapter elements 104, 200, 300, and diffusers 504, 602, 704 may be manufactured by an additive manufacture process or by an investment casting process. The adapter elements 104, 200, 300, and diffusers 504, 602, 704 may be manufactured from stainless steel. Advantageously, stainless steel is resistant to corrosion (from, for example, reductant).

The diffusers 504, 602 may be secured to a turbine housing using a press-fit, fastener or some other means of attachment.

A common example of additive manufacturing is 3D printing; however, other methods of additive manufacturing are available. Rapid prototyping or rapid manufacturing are also terms which may be used to describe additive manufacturing processes.

As used herein, “additive manufacturing” refers generally to manufacturing processes wherein successive layers of material(s) are provided on each other to “build-up” layer- by-layer or “additively fabricate”, a three-dimensional component. This is compared to some subtractive manufacturing methods (such as milling or drilling), wherein material is successively removed to fabricate the part. The successive layers generally fuse together to form a monolithic component which may have a variety of integral subcomponents. In particular, the manufacturing process may allow an example of the disclosure to be integrally formed and include a variety of features not possible when using prior manufacturing methods.

Additive manufacturing methods described herein enable manufacture to any suitable size and shape with various features which may not have been possible using prior manufacturing methods. Additive manufacturing can create complex geometries without the use of any sort of tools, molds or fixtures, and with little or no waste material. Instead of machining components from solid billets of plastic or metal, much of which is cut away and discarded, the only material used in additive manufacturing is what is required to shape the part.

Suitable additive manufacturing techniques in accordance with the present disclosure include, for example, Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS), 3D printing such as by inkjets and laserjets, Stereolithography (SLA), Direct Selective Laser Sintering (DSLS), Electron Beam Sintering (EBS), Electron Beam Melting (EBM), Laser Engineered Net Shaping (LENS), Electron Beam Additive Manufacturing (EBAM), Laser Net Shape Manufacturing (LNSM), Direct Metal Deposition (DMD), Digital Light Processing (DLP), Continuous Digital Light Processing (CDLP), Direct Selective Laser Melting (DSLM), Selective Laser Melting (SLM), Direct Metal Laser Melting (DMLM), Direct Metal Laser Sintering (DMLS), Material Jetting (MJ), NanoParticle Jetting (NPJ), Drop On Demand (DOD), Binder Jetting (BJ), Multi Jet Fusion (MJF), Laminated Object Manufacturing (LOM) and other known processes. Binder Jetting has been found to be particularly effective for manufacturing the components disclosed herein.

The additive manufacturing processes described herein may be used for forming components using any suitable material. For example, the material may be metal or any other suitable material that may be in solid, liquid, powder, sheet material, wire, or any other suitable form or combinations thereof. More specifically, according to exemplary embodiments of the present subject matter, the additively manufactured components described herein may be formed in part, in whole, or in some combination of materials including but not limited to pure metals, nickel alloys, chrome alloys, titanium, titanium alloys, magnesium, magnesium alloys, aluminum, aluminum alloys, iron, iron alloys, stainless steel, and nickel or cobalt based superalloys (e.g., those available under the name Inconel® available from Special Metals Corporation). These materials are examples of materials suitable for use in additive manufacturing processes which may be suitable for the fabrication of examples described herein.

As noted above, the additive manufacturing process disclosed herein allows a single component to be formed from multiple materials. Thus, the examples described herein may be formed from any suitable mixtures of the above materials. For example, a component may include multiple layers, segments, or parts that are formed using different materials, processes, and/or on different additive manufacturing machines. In this manner, components may be constructed which have different materials and material properties for meeting the demands of any particular application. In addition, although the components described herein are constructed entirely by additive manufacturing processes, it should be appreciated that in alternate embodiments, all or a portion of these components may be formed via casting, machining, and/or any other suitable manufacturing process. Indeed, any suitable combination of materials and manufacturing methods may be used to form these components.

Additive manufacturing processes typically fabricate components based on three- dimensional (3D) information, for example a three-dimensional computer model (or design file), of the component.

Accordingly, examples described herein not only include products or components as described herein, but also methods of manufacturing such products or components via additive manufacturing and computer software, firmware or hardware for controlling the manufacture of such products via additive manufacturing.

The structure of one or more parts of the product may be represented digitally in the form of a design file. A design file, or computer aided design (CAD) file, is a configuration file that encodes one or more of the surface or volumetric configuration of the shape of the product. That is, a design file represents the geometrical arrangement or shape of the product.

Design files can take any now known or later developed file format. For example, design files may be in the Stereolithography or “Standard Tessellation Language” (.stl) format which was created for stereolithography CAD programs of 3D Systems, or the Additive Manufacturing File (.amf) format, which is an American Society of Mechanical Engineers (ASME) standard that is an extensible markup-language (XML) based format designed to allow any CAD software to describe the shape and composition of any three- dimensional object to be fabricated on any additive manufacturing printer.

Further examples of design file formats include AutoCAD (.dwg) files, Blender (.blend) files, Parasolid (,x_t) files, 3D Manufacturing Format (,3mf) files, Autodesk (3ds) files, Collada (.dae) files and Wavefront (.obj) files, although many other file formats exist.

Design files can be produced using modelling (e.g. CAD modelling) software and/or through scanning the surface of a product to measure the surface configuration of the product.

Once obtained, a design file may be converted into a set of computer executable instructions that, once executed by a processer, cause the processor to control an additive manufacturing apparatus to produce a product according to the geometrical arrangement specified in the design file. The conversion may convert the design file into slices or layers that are to be formed sequentially by the additive manufacturing apparatus. The instructions (otherwise known as geometric code or “G-code”) may be calibrated to the specific additive manufacturing apparatus and may specify the precise location and amount of material that is to be formed at each stage in the manufacturing process. As discussed above, the formation may be through deposition, through sintering, or through any other form of additive manufacturing method.

The code or instructions may be translated between different formats, converted into a set of data signals and transmitted, received as a set of data signals and converted to code, stored, etc., as necessary. The instructions may be an input to the additive manufacturing system and may come from a part designer, an intellectual property (IP) provider, a design company, the operator or owner of the additive manufacturing system, or from other sources. An additive manufacturing system may execute the instructions to fabricate the product using any of the technologies or methods disclosed herein.

Design files or computer executable instructions may be stored in a (transitory or non- transitory) computer readable storage medium (e.g., memory, storage system, etc.) storing code, or computer readable instructions, representative of the product to be produced. As noted, the code or computer readable instructions defining the product that can be used to physically generate the object, upon execution of the code or instructions by an additive manufacturing system. For example, the instructions may include a precisely defined 3D model of the product and can be generated from any of a large variety of well-known computer aided design (CAD) software systems such as AutoCAD®, TurboCAD®, DesignCAD 3D Max, etc. Alternatively, a model or prototype of the component may be scanned to determine the three-dimensional information of the component.

Accordingly, by controlling an additive manufacturing apparatus according to the computer executable instructions, the additive manufacturing apparatus can be instructed to print out one or more parts of the product. These can be printed either in assembled or unassembled form. For instance, different sections of the product may be printed separately (as a kit of unassembled parts) and then subsequently assembled. Alternatively, the different parts may be printed in assembled form.

In light of the above, embodiments include methods of manufacture via additive manufacturing. This includes the steps of obtaining a design file representing the product and instructing an additive manufacturing apparatus to manufacture the product in assembled or unassembled form according to the design file. The additive manufacturing apparatus may include a processor that is configured to automatically convert the design file into computer executable instructions for controlling the manufacture of the product. In these embodiments, the design file itself can automatically cause the production of the product once input into the additive manufacturing device. Accordingly, in this embodiment, the design file itself may be considered computer executable instructions that cause the additive manufacturing apparatus to manufacture the product. Alternatively, the design file may be converted into instructions by an external computing system, with the resulting computer executable instructions being provided to the additive manufacturing device.

Given the above, the design and manufacture of implementations of the subject matter and the operations described in this specification can be realized using digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. For instance, hardware may include processors, microprocessors, electronic circuitry, electronic components, integrated circuits, etc. Implementations of the subject matter described in this specification can be realized using one or more computer programs, i.e., one or more modules of computer program instructions, encoded on computer storage medium for execution by, or to control the operation of, data processing apparatus. Alternatively or in addition, the program instructions can be encoded on an artificially generated propagated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus. A computer storage medium can be, or be included in, a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them. Moreover, while a computer storage medium is not a propagated signal, a computer storage medium can be a source or destination of computer program instructions encoded in an artificially generated propagated signal. The computer storage medium can also be, or be included in, one or more separate physical components or media (e.g., multiple CDs, disks, or other storage devices).

Although additive manufacturing technology is described herein as enabling fabrication of complex objects by building objects point-by-point, layer-by-layer, typically in a vertical direction, other methods of fabrication are possible and within the scope of the present subject matter. For example, although the discussion herein refers to the addition of material to form successive layers, one skilled in the art will appreciate that the methods and structures disclosed herein may be practiced with any additive manufacturing technique or other manufacturing technology.

The described and illustrated embodiments are to be considered as illustrative and not restrictive in character, it being understood that only preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected. In relation to the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used to preface a feature there is no intention to limit the claim to only one such feature unless specifically stated to the contrary in the claim. When the language "at least a portion" and/or "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary. Optional and/or preferred features as set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional and/or preferred features for each aspect of the invention set out herein are also applicable to any other aspects of the invention, where appropriate.

Claims

47 CLAIMS:

1 . A diffuser for a turbine, the diffuser comprising: an inlet having a first cross-sectional area and being configured to receive fluid; an outlet, in fluid communication with the inlet, having a second cross-sectional area, the second cross-sectional area being larger than the first cross-sectional area, the outlet being spaced apart from the inlet; a diffuser wall, which extends between the inlet and the outlet, defining an inner surface and an opposing outer surface; and a reductant barrier which extends, at least in part, from the outer surface of the diffuser wall, the reductant barrier defining a blocking face impermeable to the passage of liquids.

2. The diffuser according to claim 1 , wherein the reductant barrier is axially recessed relative to the outlet of the diffuser.

3. The diffuser according to claims 1 or 2, wherein the blocking face is substantially planar.

4. The diffuser according to claim 3, wherein the outlet is spaced apart from the inlet along a longitudinal axis, and wherein the blocking face is substantially normal to the longitudinal axis.

5. The diffuser according to any preceding claim, wherein the blocking face is recessed relative to an axially outer portion of the reductant barrier, the reductant barrier defining a pocket.

6. The diffuser according to any preceding claim, wherein the diffuser comprises a plurality of projections which extend from the outer surface of the diffuser wall, and wherein the plurality of projections comprises the reductant barrier.

7. The diffuser according to claim 6, wherein the plurality of projections define a circumferentially distributed array of projections. 48

8. The diffuser according to any preceding claim, wherein the diffuser further comprises a mounting rim configured to engage a turbine housing element.

9. The diffuser according to claim 8, wherein the reductant barrier extends between the outer surface of the diffuser wall and the mounting rim.

10. The diffuser according to any preceding claim, wherein a dosing structure aperture is provided through the diffuser wall, and wherein the reductant barrier circumferentially overlaps the dosing structure aperture.

11. The diffuser according to any preceding claim, wherein the reductant barrier comprises an opening proximate the diffuser wall, the opening being configured to permit flow of bypass gas therethrough.

12. A turbine housing assembly comprising: a turbine housing; and the diffuser according to any preceding claim; wherein the diffuser is mounted to, and at least partly within, the turbine housing.

13. An adapter element for a turbine housing, the adapter element comprising: a first connection portion configured to engage the turbine housing; a second connection portion configured to engage a conduit; an outer wall that extends between the first and second connection portions; and the diffuser according to any one of claims 1 to 11 .

14. The adapter element according to claim 13, wherein the reductant barrier extends between the diffuser wall and the outer wall.

15. The adapter element according to claim 14, wherein the blocking face extends between the diffuser wall and the outer wall.

16. A turbine assembly comprising: a turbine; and the diffuser according to any one of claims 1 to 11 , the turbine housing assembly according to claim 12, or the adapter element according to any one of claims 13 to 15. 49

17. A turbocharger comprising: a compressor; a bearing housing; and the turbine assembly according to claim 16, wherein the turbine and compressor are in power communication.

18. A diffuser for a turbine, the diffuser comprising: an inlet having a first cross-sectional area and being configured to receive fluid; an outlet, in fluid communication with the inlet, having a second cross-sectional area, the second cross-sectional area being larger than the first cross-sectional area, the outlet being spaced apart from the inlet; a diffuser wall, which extends between the inlet and the outlet, defining an inner surface and an opposing outer surface; a mounting rim, which extends from the diffuser wall, configured to engage a turbine housing; and a receiving feature, defined in the mounting rim, configured to receive a clamp member; or a clamp member that projects from the mounting rim, the clamp member defining: a bore configured to receive a fastener therethrough; and an engagement face configured to engage a mounting feature of a turbine housing.

19. A turbine housing assembly comprising: the diffuser according to claim 18, wherein the diffuser comprises the receiving feature; a turbine housing comprising a mounting feature; a fastener; and a clamp member, the clamp member defining: a bore configured to receive the fastener therethrough; and an engagement face configured to engage the mounting feature of a turbine housing; wherein the clamp member engages the receiving feature of the diffuser, and the mounting feature of the turbine housing, and is secured in position by the fastener, to mount the diffuser to, and at least partly within, the turbine housing. 50

20. A turbine housing assembly comprising: the diffuser according to claim 18, wherein the diffuser comprises the clamp member; a turbine housing comprising a mounting feature; and a fastener; wherein the clamp member engages the mounting feature of the turbine housing, and is secured in position by the fastener to mount the diffuser to, and at least partly within, the turbine housing.

21. The turbine housing assembly according to claims 19 or 20, wherein the fastener is received through the bore of the clamp member, and wherein a torque communication feature of the fastener is proximate the outlet of the diffuser.

22. A method of assembling the turbine housing assembly according to any one of claims 19 to 21 , the method comprising the steps of: i) inserting the diffuser at least partly into the turbine housing and aligning the receiving feature, or clamp member, with the mounting feature; ii) urging the engagement face of the clamp member into engagement with the mounting feature; and iii) securing the clamp member in position using the fastener.

23. A kit of parts comprising: the diffuser according to claim 18; and the turbine housing according to claim 19; and optionally the clamp member according to claim 18.

24. A computer program comprising computer executable instructions that, when executed by a processor, cause the processor to control an additive manufacturing apparatus to manufacture the diffuser according to any one of claims 1 to 11 or 18, or the adapter element according to any one of claims 13 to 15.

25. A method of manufacturing the diffuser according to any one of claims 1 to 11 or 18, or the adapter element according to any one of claims 13 to 15, via additive manufacturing, the method comprising: obtaining an electronic file representing a geometry of the diffuser or adapter element; and controlling an additive manufacturing apparatus to manufacture, over one or more additive manufacturing steps, the diffuser or adapter element according to the geometry specified in the electronic file.