GB2554355A

GB2554355A - An exhaust gas treatment assembly

Info

Publication number: GB2554355A
Application number: GB1616050.9A
Authority: GB
Inventors: William Barr Gerald
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2016-09-21
Filing date: 2016-09-21
Publication date: 2018-04-04
Anticipated expiration: 2036-09-21
Also published as: GB201616050D0; GB2554355B

Abstract

An exhaust gas treatment assembly 200 and method of use thereof comprising a catalyst 204, a duct 202 configured to carry exhaust gases from an exhaust pipe 19 to the catalyst and a movable element 206 configured to guide exhaust gases from the duct into the catalyst. Element is movable between a first position in which the exhaust gases are directed into a sub-portion 204a of the catalyst and a second position in which the exhaust gases are able to flow into a remaining portion 204b of the catalyst. The movable element may be a tube slidably disposed within, or partially received in the duct. The first position may be an extended position where the movable element extends from the duct and the second position may be a retracted position where the element is retracted from the catalyst. The remaining portion of the catalyst may be radially outside the sub-portion of the catalyst and may be outside the movable element. The movable element may have an actuator to move it. The position of the element may be moved upon determination of a catalyst threshold temperature or predicted temperature. The element may be moved after a predetermined time period.

Description

(71) Applicant(s):

Ford Global Technologies, LLC (Incorporated in USA - Delaware)

Suite 800, Fairlane Plaza South,

330 Town Center Drive, Dearborn 48126, Michigan, United States of America (56) Documents Cited:

WO 2008/103109 A1 JP 2010001748 A US 20090183496 A1

DE 003738538 A1 US 20160138453 A1 (58) Field of Search:

INT CL F01N

Other: WPI, EPODOC, TXTT, TXTE (72) Inventor(s):

Gerald William Barr (74) Agent and/or Address for Service:

Haseltine Lake LLP

5th Floor Lincoln House, 300 High Holborn, LONDON, WC1V 7JH, United Kingdom (54) Title of the Invention: An exhaust gas treatment assembly

Abstract Title: Exhaust gas treatment assembly with movable gas flow guide element (57) An exhaust gas treatment assembly 200 and method of use thereof comprising a catalyst 204, a duct 202 configured to carry exhaust gases from an exhaust pipe 19 to the catalyst and a movable element 206 configured to guide exhaust gases from the duct into the catalyst. Element is movable between a first position in which the exhaust gases are directed into a sub-portion 204a of the catalyst and a second position in which the exhaust gases are able to flow into a remaining portion 204b of the catalyst. The movable element may be a tube slidably disposed within, or partially received in the duct. The first position may be an extended position where the movable element extends from the duct and the second position may be a retracted position where the element is retracted from the catalyst. The remaining portion of the catalyst may be radially outside the sub-portion of the catalyst and may be outside the movable element. The movable element may have an actuator to move it. The position of the element may be moved upon determination of a catalyst threshold temperature or predicted temperature. The element may be moved after a predetermined time period.

Figure 2a

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An exhaust gas treatment assembly

Technical Field

The present disclosure relates to an exhaust gas treatment assembly for a motor vehicle and is particularly, although not exclusively, concerned with an exhaust gas treatment assembly configured to reduce a warm-up time of a catalyst of the exhaust gas treatment assembly.

Background

Motor vehicles typically comprise one or more exhaust gas treatment devices configured to reduce the quantities of polluting substances within exhaust gases emitted by the vehicle.

Many exhaust gas treatment devices comprise a catalyst configured to increase the rate of a reaction by which one or more polluting substances are captured within the exhaust treatment device, or converted into non-polluting substances that may be emitted from the vehicle.

The ability of a catalyst to increase the rate of the reaction is often determined by an operating temperature of the catalyst. Furthermore, a catalyst may not begin catalysing a reaction with a polluting substance until the catalyst has been heated to a light-off temperature of the catalyst.

When an engine of a motor vehicle is first started, the catalysts within any exhaust gas treatment devices provided on the vehicle are often cold, and hence, the exhaust gas treatment devices may operate less effectively until they have been heated by the exhaust gases to a desirable operating temperature. It is therefore often desirable to reduce the time taken for catalysts of an exhaust after treatment device to be heated to the desirable operating temperature.

Statements of Invention

According to an aspect of the present disclosure, there is provided an exhaust gas treatment assembly for a motor vehicle, the assembly comprising: a catalyst; a duct configured to carry exhaust gases from an exhaust pipe to the catalyst; and a movable element configured to guide exhaust gases from the duct into the catalyst, wherein the movable element is movable between: a first position in which the exhaust gases are directed into a sub-portion of the catalyst; and a second position in which the exhaust gases are able to flow into a remaining portion of the catalyst.

The movable element may comprise a tube slidably disposed in the duct. The movable element may be the tube, e.g. the movable element may be a tubular movable element.

The movable element may be at least partially received within the duct. The first position may be an extended position, in which at least a portion of the movable element extends from the duct towards the catalyst. The second position may be a retracted position in which the movable element is retracted away from the catalyst into the duct.

The catalyst may be arranged downstream of the movable element. The remaining portion of the catalyst may be arranged radially outside of the sub-portion of the catalyst. The remaining portion of the catalyst may be arranged radially outside of the movable element. The remaining portion of the catalyst may be arranged radially outside of the exhaust pipe. The remaining portion may be a substantially annular portion of the catalyst. The remaining portion may substantially surround the subportion of the catalyst. The catalyst may present a larger cross sectional flow area to the exhaust gases than the exhaust pipe.

The assembly may further comprise an exhaust gas directing element configured to direct exhaust gases passing the movable element towards the sub-portion of the catalyst when the movable element is in the first position. The movable element may be configured to direct exhaust gases at or into the exhaust gas directing element when the movable element is in the first position.

The exhaust gas directing element may comprise, or may be, a fixed tube extending from the catalyst towards the duct. When the movable element is in the first position, exhaust gases may flow from the tubular movable element into the fixed tube. The fixed tube may be substantially the same diameter at the tubular movable element. Alternatively, the tubular movable element may be configured to be at least partially received within the fixed tube, or vice versa.

A gap may be provided between the duct and the movable element. The assembly may further comprise a flow guide provided in the duct. The flow guide may be configured to discourage exhaust gases from flowing into the gap, e.g. the flow guide may be configured to encourage exhaust gases to flow past the gap to the movable element.

The assembly may further comprise an actuator configured to control the position of the movable element. The actuator may be electrically, pneumatically or hydraulically powered. The exhaust gas treatment assembly may further comprise a controller configured to control the operation of the actuator.

An engine assembly or motor vehicle may comprise the above mentioned exhaust gas treatment assembly.

According to an aspect of the present disclosure, there is provided an exhaust gas treatment assembly, such as a catalytic converter assembly, for a motor vehicle, the assembly comprising: a duct configured to lead from an exhaust pipe to a catalyst, the catalyst presenting a larger cross-sectional flow area to a flow of exhaust gases than the exhaust pipe; and a tube slidably disposed in the duct, the tube being configured to guide the exhaust gases from the exhaust pipe to the catalyst, wherein the tube is arranged such that the exhaust gases are directed to a sub portion of the catalyst when the tube is in an extended position and the exhaust gases are able to flow into the remainder of the catalyst when the tube is in a retracted position.

According to another aspect of the present disclosure, there is provided an exhaust gas treatment assembly for a motor vehicle, the assembly comprising: a catalyst having first and second portions; a duct configured to carry exhaust gases from an exhaust pipe to the catalyst; and a movable element configured to guide exhaust gases from the duct into the catalyst, wherein the movable element is movable between: a first position in which the exhaust gases are directed into the first portion of the catalyst only; and a second position in which the exhaust gases are able to flow into the first and second portions of the catalyst.

According to another aspect of the present disclosure, there is provided a method of operating an exhaust gas treatment assembly of a motor vehicle, the exhaust gas treatment assembly comprising: a catalyst; a duct configured to carry exhaust gases from an exhaust pipe to the catalyst; and a movable element configured to guide exhaust gases from the duct into the catalyst, wherein when the movable element is movable between: a first position in which the exhaust gases are directed into a subportion of the catalyst; and a second position in which the exhaust gases are able to flow into a remaining portion of the catalyst, wherein the method comprises: positioning the movable element in the first position; and moving the movable element towards, or into, the second position following a period of operation of the motor vehicle.

The method may further comprise determining a temperature of the catalyst, e.g. using a temperature sensor provided in the exhaust gas treatment assembly. The movable element may be moved towards the second position when the temperature of the catalyst is at or greater than a threshold temperature.

The method may further comprise predicting a temperature of the catalyst, e.g. based on one or more operating parameters of the engine, such as the engine running speed and/or engine power output. The movable element may be moved towards the second position when the temperature of the catalyst is predicted to be at or greater than a threshold temperature.

The movable element is moved towards the second position after the motor vehicle has been operating for a predetermined period of time.

To avoid unnecessary duplication of effort and repetition of text in the specification, certain features are described in relation to only one or several aspects or embodiments of the invention. However, it is to be understood that, where it is technically possible, features described in relation to any aspect or embodiment of the invention may also be used with any other aspect or embodiment of the invention.

Brief Description of the Drawings

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:

Figure 1 is a schematic representation of an engine assembly for a motor vehicle;

Figure 2a is a schematic representation of an exhaust gas treatment assembly according to arrangements of the present disclosure, in a first configuration;

Figure 2b is a schematic representation of the exhaust gas treatment assembly in a second configuration;

Figure 3 shows a method of operating an exhaust gas treatment assembly, according to arrangements of the present disclosure;

Figure 4 is a schematic representation of an exhaust gas treatment assembly according to another arrangements of the present disclosure;

Figure 5 is a schematic representation of an exhaust gas treatment assembly according to another arrangements of the present disclosure; and

Figure 6 is a schematic representation of an exhaust gas treatment assembly according to another arrangements of the present disclosure.

Detailed Description

With reference to Figure 1, an engine assembly 100 for a vehicle, e.g. a motor vehicle is described. Air may enter through an inlet 12 and then pass through an air filter 13 via an inlet duct 46. The air may be throttled by a valve 36 before being passed through a compressor 14a of a turbocharger 14. The turbocharger 14 may improve the engine power output and reduce emissions. Typically, the turbocharger 14 is arranged with an exhaust gas driven turbine 14b driving the compressor 14a mounted on the same shaft. The air may then enter an internal combustion engine 10 via a throttle 18 configured to vary the mass flow of air into the internal combustion engine.

A charge air cooler 16 may be provided upstream of the engine to further increase the density of the air entering an internal combustion engine 10, thereby improving its performance.

In a particular arrangement of the present disclosure, the internal combustion engine 10 comprises a diesel engine, however it is equally envisaged that the engine 10 may be a spark ignition engine. As depicted in Figure 1, the internal combustion engine 10 may comprise a number of cylinders 10a-d and the air may flow into each of these cylinders at an appropriate time in the engine’s cycle as determined by one or more valves (not shown).

Exhaust gases leaving the cylinders 10a-d of the internal combustion engine 10 may enter an exhaust pipe 19 of the engine assembly. The exhaust pipe 19 may carry the exhaust gases from the engine 10 to an exhaust outlet 23 where the exhaust gases are emitted from the vehicle.

A first EGR loop 22 configured to selectively recirculate exhaust gases from the internal combustion engine 10 back into the internal combustion engine via a first EGR duct 42 may also be provided. The first EGR loop 22 may be provided about the turbocharger 14 such that exhaust gases leaving the turbine 14b may be recirculated into the inlet of compressor 14a. The first EGR loop 22 may be diverted from the main exhaust flow path, e.g. from the exhaust pipe 19. The first EGR loop 22 may be diverted from the main exhaust flow upstream or downstream of the exhaust treatment assembly 200 described below. The first EGR loop 22 may comprise a first recirculation valve 24, which may control the amount of recirculation through the first EGR loop 22.

A second EGR loop 32 configured to selectively recirculate exhaust gases from the internal combustion engine 10 back into the internal combustion engine via a second EGR duct 44 may also be provided. The second EGR loop 32 may be provided about the engine 10 with exhaust gases leaving the engine 10 being recirculated to the air inlet of the engine 10. The second exhaust gas recirculation loop 32 may be diverted from the main exhaust flow path, e.g. from the exhaust pipe 19, at a point between the engine 10 and the turbine 14b of the turbocharger. Accordingly, the exhaust gases in the second EGR loop 32 may be at a higher pressure than the exhaust gases in the first EGR loop 22. The second exhaust gas recirculation loop 32 may comprise a second recirculation valve 34 which may control the amount of recirculation in the second EGR loop 32.

An exhaust treatment assembly 200 may be provided downstream of the turbine 14b and the second EGR loop 32. As mentioned above, the exhaust treatment assembly 200 may be upstream or downstream of the first EGR loop 22, e.g. the point at which the first EGR loop branches from the main exhaust flow path. Exhaust gases that are not recirculated within the first and/or second EGR loops 22, 32 may pass though the exhaust treatment assembly 200 before being exhausted from the vehicle. Additionally, as shown in Figure 1, exhaust gases may pass through the exhaust treatment assembly 200 prior to being recirculated within the first EGR loop 22. By passing the exhaust gases through the exhaust treatment assembly 200, emissions from the vehicle may be reduced.

The exhaust treatment assembly 200 may comprise one or more of a Selective Catalytic Reduction (SCR) device, a Lean NOx Trap (LNT), an oxidation catalyst, e.g. a diesel oxidation catalyst, a particulate filter, e.g. a Diesel Particulate Filter (DPF), a Passive NOx Adsorber, such as an LNT life, or any other exhaust treatment device. The Exhaust treatment assembly may comprise any combination of exhaust treatment devices. For example, the exhaust gas treatment assembly 200 may be a combined SCR/DPF device. As depicted in Figure 1, the engine assembly may comprise a further exhaust treatment assembly 201, e.g. downstream of the exhaust treatment assembly 200, comprising one or more further exhaust treatment devices.

With reference to Figures 2a and 2b, an exhaust treatment assembly 200 according to arrangements of the present disclosure, will now be described. The exhaust treatment assembly 200 comprises a duct 202 configured to carry exhaust gas from the exhaust pipe 19 to a catalyst 204.

The catalyst 204 may be configured to increase the rate of a reaction of the exhaust gases within the exhaust treatment assembly 200. The reaction of the exhaust gases within the exhaust treatment assembly 200 may lead to a reduction in the quantities of polluting substances present within the exhaust gases. Additionally or alternatively, the catalyst 204 may be configured to react, e.g. directly react, with one or more of the polluting substances within the exhaust gases, in order to capture the substances within the exhaust treatment assembly 200, or to convert the polluting substances into less polluting substances.

The efficiency with which the catalyst 204 reacts with the exhaust gases and/or increases the rate of a reaction of the exhaust gases may depend on the temperature of the catalyst 204. In some arrangements, the catalyst 204 may not begin to react with and/or catalyse the reaction of the exhaust gases until the catalyst has been heated to a “light off” temperature of the catalyst.

When the engine assembly 100 begins operating, the catalyst 204 may be cold, and hence, the exhaust treatment assembly may not operate efficiency. However, during operation of the engine assembly 100, hot exhaust gases leaving the engine 10 may flow through the exhaust treatment assembly 200 and may heat the catalyst 204 to a temperature at which it begins operating effectively.

In some arrangements of the disclosure, the catalyst 204 comprise a substrate, e.g. a metal substrate, provided with a catalytic material on one or more surfaces of the substrate. For example, a wash coat containing the catalytic material may be applied to the substrate and may form a coating on the surface of the substrate. The substrate and/or the catalytic material may be configured to provide a high surface area at which reactions of the exhaust gases may take place in the presence of the catalyst. For example, the substrate may form a lattice, such as a honeycomb lattice.

As depicted in Figures 2a and 2b, the catalyst 204 may comprise a first portion 204a and a second portion 204b. The first portion 204a of the catalyst may be a central portion of the catalyst and the second portion 204b may be provided radially outside of the first portion 204a. In the arrangement depicted, the first portion 204a is substantially the same diameter as the duct 202. However, it is equally envisaged that the first portion 204a may have a smaller or larger diameter.

As shown, at least part of the second portion 204b is provided radially outside of the duct 202 and/or the exhaust pipe 19. In other words, the catalyst 204 may provide a larger cross-sectional flow area for the exhaust gases than the duct 202 or the exhaust pipe 19.

In order to encourage exhaust gases flowing through the duct 202 to flow through the total cross-sectional flow area of the catalyst 204, the exhaust treatment assembly may further comprise a diffuser 203 provided between the duct 202 and the catalyst. As the flow of exhaust gases passes through the diffuser 203 the cross-sectional flow area of the diffuser changes, e.g. increases, to become substantially equal to or greater than the flow area of the catalyst 204. As depicted in Figures 2a and 2b, the diffuser 203 may form a portion of a cone. However, it is equally envisaged that the diffuser 203 may form any other suitable shape. Although the diffuser 203 has been described as a separate component to the duct 202, it is equally envisaged that the diffuser 203 may be a portion of the duct 202 along which the flow area of the duct increases.

The catalyst, e.g. the substrate of the catalyst, may be configured to define one or more channels extending from a front end 204’ of the catalyst to a rear end 204” of the catalyst. For example, the first portion 204a may comprise one or more first channels, and the second portion 204b may comprise one or more second channels arranged about the first channels. The first and second channels may be open at the front and rear ends of the catalyst to allow exhaust gases to enter the channels and flow through the catalyst. The channels may be configured to allow exhaust gases to pass between the channels, as the exhaust gas flows through the catalyst. Alternatively, the channels may be configured such that exhaust gases are contained within the channels as the exhaust gases flow through the catalyst and are prevented from passing between the channels.

As depicted in Figures 2a and 2b, the first and second portions 204a, 204b of the catalyst may be separated by a barrier 204c. The barrier 206c may be configured to prevent exhaust gases passing between the first and second portions 204a, 204b of the catalyst, e.g. between the channels formed in the first and second portions respectively. Alternatively, the barrier 204c may be permeable and may allow exhaust gases to pass between the first and second portions.

The exhaust treatment assembly 200 may comprise a housing 208 and the catalyst, e.g. the substrate on which the catalytic material is provided, may be provided within the housing 208. The catalyst 204 may be mounted to the housing. However in other arrangements, the housing 208 may be integral with the catalyst 208. For example, the housing 208 may be provided by an outer wall of the catalyst substrate.

The exhaust treatment assembly 200 further comprises a movable element 206 configured to guide exhaust gases from the duct 202 to the catalyst 204. The movable element 206 may be movable between a first position, as depicted in Figure 2a, in which the movable element 206 acts to direct exhaust gases into the first portion of the catalyst 204a and a second position, as depicted in Figure 2b, in which the movable element is arranged such that exhaust gases are encouraged to flow into the second portion of the catalyst 204b, e.g. in addition to the first portion 204a.

The movable element 206 may be provided within the duct 202. As depicted in Figures 2a, 2b and 3, the movable element may be configured to be at least partially received within the duct 202. In some arrangements, when the movable element 206 is in the second position the movable element may be substantially completely received within the duct 202, such that the cross-sectional flow area of the exhaust gases is encouraged to expand over the length of the diffuser 203, as described above, in order to flow into the catalyst over substantially the total cross-section area of the catalyst 204.

In the arrangement depicted, the movable element 206 comprises a tube disposed within the duct 202 and configured to slide into and out of the duct. When the movable element 206 is in the first position, e.g. an extended position, as shown in Figure 2a, the tube may extend between the duct 202 and the catalyst 204 and may direct exhaust gases from the duct 202 into the first portion 204a of the catalyst 204. Furthermore, when the movable element 206 is in the first position, the exhaust gases may flow within the tube of the movable element when passing through the diffuser 203, and hence, the flow area of the exhaust gases may be discouraged or prevented from expanding such that the exhaust gases flow into the second portion 204b of the catalyst.

As shown in Figure 2b, when the movable element 206 comprises the tube, when the movable element 206 is in the second position, e.g. a retracted position, the tube may be substantially completely received within the duct 202 and may not prevent the flow of exhaust gases from expanding within the diffuser to flow into the second portion 204b of the catalyst.

When the engine assembly 100 begins operating and the catalyst 204 is cold, the catalyst may not operate effectively. By controlling the position of the movable element

206 it is possible to control the flow of exhaust gases, such that the exhaust gases flow through a sub-portion of the catalyst, e.g. through the first portion only. A smaller portion of the catalyst 204 is exposed initially to the hot exhaust gases leaving the engine. This increases the rate at which the portion of the catalyst is heated to a suitable temperate to begin operating effectively. By heating a sub-portion of the catalyst 204 to a desired operating temperature, the overall efficiency of the catalyst 204 may be increased compared to if the whole of the catalyst was heated to a lower temperature.

Once the first portion 204a of the catalyst has been heated to a desirable temperature, the position of the movable element 206 may be controlled, e.g. the movable element may be moved into the second position, to allow exhaust gases to flow through the second portion 204b of the catalyst 204 and heat the second portion to the desired operating temperature.

The exhaust treatment assembly 200 may further comprise an actuator 210 configured to control the position of the movable element 206 by virtue of a control linkage 220. As depicted in Figures 2a and 2b, the control linkage 220 may comprise a control rod 222 coupled to diffuser 203 at a pivot 224. As depicted, the diffuser 203 may comprise a boss or extension 203a configured to support the pivot 224. A gas seal 223 may be provided between the extension 203a of the diffuser and the control rod 222, e.g. at or adjacent to the pivot 224, to prevent exhaust gases leaking out of the diffuser around the control rod 222.

The control rod 222 may have a first end 222a and a second end 222b. A connector 226, such as a clevis or yoke, may be provided at the first end 222a. The connector 226 may be coupled to the movable element 206. For example, the connector may be coupled to a corresponding connector, a pin, a slot or any other suitable feature provided on the movable element 206. The actuator 210 may be configured to act against the second end 222b of the control rod 222 to pivot the control rod 222 about the pivot 224 and thereby adjust the position of the movable element 206.

The actuator 210 may be hydraulically, pneumatically or electrically powered. A controller 230 may be configured to control the operation of the actuator. The controller 230 may be a powertrain control module or body control module of the vehicle.

Alternatively, the controller 230 may be any other controller of the vehicle or may be a dedicated controller provided within the exhaust treatment assembly 200.

With reference to Figure 3, the controller 230 may control the operation of the actuator 210 according to a method 300. The method 300 comprises a first step 302, in which the movable element 206 is positioned in the first position. The method 300 further comprises a second step 306, in which the movable element 206 is moved towards the second position.

The second step 306 may be performed following a predetermined period of operation of the engine assembly 100. For example, it may be determined that the first portion 204a of the catalyst is likely to reach the desired operating temperature following a particular period of operation of the engine assembly and the movable element may be moved accordingly. In other words, the movable element 206 may be moved from the first position into the second position after the engine assembly 100 has been operating for a predetermined period of time.

Alternatively, the method may comprise a determination step 304, in which a temperature of the catalyst 204 or a portion of the catalyst, such as the first portion 204a, is determined. The second step 306 may be performed when the temperature of the catalyst 204 or the portion of the catalyst is equal to or greater than a threshold value, e.g. when the temperature of the catalyst reaches the desired operating temperature.

The temperature of the catalyst may be determined in the determination step 304 by referring to a measurement recorded by a temperature sensor provided in the exhaust treatment assembly, such as the temperature sensor 432 shown in Figure 4, as described below. Alternatively, the temperature of the catalyst may be predicted according to operating parameters of the engine assembly 100, such as a position of the throttle 13, an amount of fuel injected in to the cylinders 10a-d, and/or any other operating parameter of the engine.

Wth reference to Figure 4, an exhaust treatment assembly 400 according to another arrangement of the present disclosure will now be described. The exhaust treatment assembly 400 comprises a duct 402 and a diffuser 403, which are similar to the duct 202 and diffuser 203 shown in Figure 2a and 2b. The exhaust treatment assembly 400 also comprises a catalyst 404, a movable element 406 and a housing 408, which are similar to the catalyst 204 the movable element 206 and the housing 208 respectively.

As mentioned above, the exhaust gas assembly 400 may further comprise a temperature sensor 432 configured to allow a temperature of the catalyst, e.g. the first portion 404a of the catalyst to be determined. The temperature sensor 432 may be coupled to a controller

As depicted in Figure 4, the movable element 406, e.g. an outer diameter of the movable element, may be configured such that a gap 407 is formed between the movable element 406 and the duct 402, e.g. when the movable element is at least partially received within the duct, this may reduce the likelihood of the movable element 406 becoming lodged in the duct 402, for example as the relative temperatures of the movable element 406 and the duct 402 vary and the movable element and the duct expand and contract due to the changing temperatures. However, during operation of the engine assembly 100, particles present in the exhaust gases may flow into the gap. The particles may become stuck in the gap and may act to bind the movable element 406 in the duct 402.

In order to reduce to amount of particles entering and building up within the gap 407, the exhaust treatment assembly 400 may comprise a flow guide 405 provided within the duct 402 and configured to discourage the exhaust gases from flowing into the gap. For example, as shown in Figure 4, the flow guide 405 may be configured to direct the exhaust gases towards the centre of the duct 402 and away from the gap. As depicted in Figure 4, the flow guide 405 may be provided within the duct 402 a sufficient distance away from the catalyst 404 such that the flow guide 405 does not interfere with movement of the movable element 406 between the first and second positions. For example, the flow guide may be provided at a distance from a first end 402a of the duct, which is greater than a length of the movable element 406, e.g. a length of the movable element that is received within the duct 402 when the movable element 406 is in the second position.

The exhaust treatment assembly may further comprise an exhaust directing element 414 configured to guide exhaust gases that have passed the movable element towards the first portion 404a of the catalyst. The exhaust directing element 414 may be coupled to the catalyst 404. In some arrangements, the exhaust directing element 414 may be formed by the catalyst 404, e.g. a portion of the substrate of the catalyst may extend towards the duct 402 to form the exhaust directing element 414.

As depicted in Figure 4, the exhaust directing element 414 may comprise a tube extending from the catalyst 404 towards the duct 402. The tube may be a cylindrical tube, a square tube, an octagonal tube or may be any other shape in cross-section. In some arrangements, the shape of the tube may be configured to surround a perimeter of the first portion of the catalyst. For example, the tube may be a cylindrical tube substantially the same diameter as the first portion 404a.

Additionally or alternatively, when the movable element 406 comprises a tubular movable element, the cross-sectional shape of exhaust directing element 414 may be similar to the cross-sectional shape of the movable element 406. Additionally, the exhaust directing element may be substantially the same size, e.g. define the same flow area, as the movable element 406, such that exhaust gases may flow smoothly from the movable element to the exhaust directing element 414, e.g. without a change in the flow area of the exhaust gases. In some arrangements, the exhaust directing element 414 may be configured such that the movable element 406 may be at least partially received within the exhaust directing element 414.

By providing the exhaust directing element 414, the distance moved by the movable element 406 between the first and second positions may be reduced, without compromising the ability of the movable element to direct exhaust gases towards the first portion 404a of the catalyst. Reducing the distance between the first and second positions may reduce the maximum distance between the movable element 406 and the flow guide 405, which may improve the ability of the flow guide to direct exhaust gases away from the gap 407.

The exhaust treatment assembly 400 comprises control mechanism 420 having a control rod 422 and a connector 426 coupled to the control rod 422. In some arrangements, the connector 426 may be coupled to a point 427 on the movable element located at or towards a central axis of the duct. When the control mechanism 420 applies a force to the movable element to move the moveable element between the first and second positions, the force may be applied at the point 427. A moment generated on the movable element by applying the force may therefore be reduced compared to arrangements in which the point 427 is provided away from the central axis of the duct 402. Reducing the moment applied to the movable element may reduce the likelihood of the movable element becoming wedged or stuck when moving between the first and second positions.

With reference to Figure 5, an exhaust treatment assembly 500, according to another arrangement of the present disclosure, comprises a duct 502, diffuser 503 and a catalyst 504 that are similar to the ducts 202, 402, diffusers 203, 403 and catalysts 204, 404 described above.

The exhaust treatment assembly 500 further comprises a movable element 506, which is similar to the movable element 206, 406 except that the movable element comprises one or more bosses 507 extending from the movable element 506 in a radially outward direction. As depicted in Figures 5, the bosses may extend outside, e.g. radially outside, a wall 502a of the duct, e.g. via openings 502b provided in the wall 502a of the duct.

The exhaust treatment assembly 500 further comprises one or more covers 505 coupled to the duct 502 configured to receive the bosses 507. The covers 505 may cover the openings 502b formed in the wall of the duct and may be sealed against the wall 502a of the duct to prevent exhaust gases from leaking out of the exhaust treatment assembly. The covers 505 and the openings 502b may extend along the duct 502 a length that is equal to or greater than the distance moved by the movable element 506 between the first and second positions such that the bosses 507 do not interfere with the wall 502a or the covers 505 when the movable element is moved between the first and second positions.

In the arrangement shown in Figure 5, separate covers 505 are provided at each of the openings 502b. However, it is equally envisaged that the covers 505 may extend around the duct 502 and may cover more than one of the opening 502b. In some arrangements, a single cover 505 may be provided that extends around the circumference of the duct 502 and covers each of the openings 502b.

The exhaust treatment assembly 500 further comprises a control mechanism 520 comprising one or more actuators 510, which control the position of the movable element via respective control rods 522. Unlike in the arrangements shown in Figure 2b, 2b and 4, control rods 522 may not be pivotally coupled to the duct 502 or diffuser

503, but may be configured to move linearly, e.g. along respective axes of the control rods 522, under the action of the actuator 510. The control rods 522 may extend from the actuators 510 into the covers 505 and may be coupled to the bosses 507 of the movable element. The movable element 506 is thereby moved between the first and second positons by forces applied at the bosses 507 of the movable element.

Gas seals 523 may be provided between the control rods 522 and the covers 505 to prevent exhaust gases from leaking out of the covers 505. Alternatively, in other arrangements of the disclosure, the actuators 510 and the control rods 522 may be provided within the covers 505, which may define sealed chambers.

As shown in Figure 5, the exhaust treatment assembly 500 may comprise two actuators 510 provided at a top and bottom of the duct, e.g. vertically spaced about the duct. However, it is equally envisaged that the actuators 510 may be laterally spaced about the duct. In other arrangements, 1, 3, 4 or more actuators 510 may be spaced around the duct with any desired spacing, e.g. angular spacing, about a central axis of the duct 502. The number and arrangement of the covers 505 and actuators 510 may correspond to the number and arrangement of bosses 507 provided on the movable element 506.

Controlling the position of the movable element by providing force from an actuator at two or more positions around the movable element may cancel out moments or couples generated on the movable element due to the forces applied by the actuators 510. Hence, the likelihood of the movable element becoming wedged or stuck as is moves between the first and second positions may be reduced.

In the arrangement shown in Figures 2a, 2b, 4 and 5, the actuators 210, 410, 510 are linear actuators configured to apply force in a linear direction. However, in other arrangements of the present disclosure, the actuator may be a rotary actuator.

With reference to Figure 6, an exhaust treatment assembly 600, according to another arrangement of the present disclosure, comprises a control mechanism 620 including two rotary actuators 610 spaced about a duct 602. As shown, the actuators 610 may be configured to rotate respective pinon gears 622 that mesh with racks 623 provided on a movable element 606 of the exhaust treatments assembly 600 in order to move the movable element 606 between first and second positions.

As shown in Figure 6, the exhaust treatment assembly 600 may comprise two rotary actuators 610 provided at a top and bottom of the duct, e.g. vertically spaced about the duct. However, it is equally envisage that the actuators 610 may be laterally spaced about the duct. In other arrangements, 1, 3, 4 or more actuators 610 may be spaced around the duct with any desired spacing, e.g. angular spacing, about a central axis of the duct 602. The number and arrangement of the rotary actuators 610 may correspond to the number and arrangement of the racks 623 provided on the movable element 606.

The rotary actuators 610 may be electrically driven. In other words, the rotary actuator may comprise an electric motor. The electric motor may comprise an encoder such that the rotation of the actuator may be accurately controlled. In some arrangements, the electric motor may be a stepper motor. Alternatively, the rotary actuator 610 may be a hydraulic or pneumatically powered actuator.

As depicted in Figure 6, the rotary actuators 610 and the pinion gears 622 may be housed within covers 605 coupled to the duct 602 and/or diffuser 603. The covers 605 may create sealed housings for the rotary actuators and prevent exhaust gases leaking from the exhaust treatment assembly 600.

In the arrangement shown in Figure 6, separate covers 605 are provided at each of the rotary actuators 610. However, it is equally envisaged that the covers 605 may extend around the duct 602 and may cover more than one of the rotary actuators 610. In some arrangements, a single cover 605 may be provided that extends around the circumference of the duct 602 and covers each of the rotary actuators.

In the arrangement shown, the pinion gears 622 are coupled, e.g. directly coupled, to the rotary actuators and rotated directly by the rotary actuators. However, in other arrangements, the pinon gears 622 may be driven by the rotary actuator by virtue of one or more gears (not shown) provided within the control mechanism 620.

It will be appreciated by those skilled in the art that although the invention has been described by way of example, with reference to one or more exemplary examples, it is not limited to the disclosed examples and that alternative examples could be constructed without departing from the scope of the invention as defined by the appended claims.

Claims

1. An exhaust gas treatment assembly for a motor vehicle, the assembly comprising:

a catalyst;

a duct configured to carry exhaust gases from an exhaust pipe to the catalyst; and a movable element configured to guide exhaust gases from the duct into the catalyst, wherein the movable element is movable between:

a first position in which the exhaust gases are directed into a sub-portion of the catalyst; and a second position in which the exhaust gases are able to flow into a remaining portion of the catalyst.

2. The exhaust gas treatment assembly of claim 1, wherein the movable element comprises a tube slidably disposed in the duct.

3. The exhaust gas treatment assemble of claim 1 or 2, wherein the movable element is at least partially received within the duct.

4. The exhaust gas treatment assembly of any of the preceding claims, wherein when the first position is an extended position, in which at least a portion of the movable element extends from the duct towards the catalyst and the second position is a retracted position in which the movable element is retracted away from the catalyst into the duct.

5. The exhaust gas treatment assembly of any of the preceding claims, wherein the catalyst is arranged downstream of the movable element.

6. The exhaust gas treatment assembly of any of the preceding claims, wherein the remaining portion of the catalyst is arranged radially outside of the sub-portion of the catalyst.

7. The exhaust gas treatment assembly of any of the preceding claims, wherein the remaining portion of the catalyst is arranged radially outside of the movable element.

8. The exhaust gas treatment assembly of any of the preceding claims, wherein the assembly further comprises an exhaust gas directing element configured to direct exhaust gases passing the movable element towards the sub-portion of the catalyst when the movable element is in the first position.

9. The exhaust gas treatment assembly of claim 8, wherein the exhaust gas directing element comprises a fixed tube extending from the catalyst towards the duct.

10. The exhaust gas treatment assembly of any of the preceding claims, wherein a gap is provided between the duct and the movable element.

11. The exhaust gas treatment assembly of claim 10, wherein the assembly further comprises a flow guide provided in the duct, wherein the flow guide is configured to discourage exhaust gases from flowing into the gap.

12. The exhaust gas treatment assembly of any of the preceding claims, wherein the assembly further comprises an actuator configured to control the position of the movable element.

13. An engine assembly or motor vehicle comprising the exhaust gas treatment assembly of any of the preceding claims.

14. A method of operating an exhaust gas treatment assembly of a motor vehicle, the exhaust gas treatment assembly comprising:

a catalyst;

a duct configured to carry exhaust gases from an exhaust pipe to the catalyst; and a movable element configured to guide exhaust gases from the duct into the catalyst, wherein when the movable element is movable between:

a first position in which the exhaust gases are directed into a sub-portion of the catalyst; and a second position in which the exhaust gases are able to flow into a remaining portion of the catalyst, wherein the method comprises:

positioning the movable element in the first position; and moving the movable element towards the second position following a period of operation of the motor vehicle.

15. The method of claim 14, wherein the method further comprises determining a temperature of the catalyst, wherein the movable element is moved towards the second position when the temperature of the catalyst is at or greater than a threshold temperature.

16. The method of claim 14, wherein the method further comprises predicting a temperature of the catalyst, wherein the movable element is moved towards the second position when the temperature of the catalyst is predicted to be at or greater than a threshold temperature.

17. The method of any of claims 14 to 16, wherein the movable element is moved towards the second position after the motor vehicle has been operating for a predetermined period of time.

Intellectual

Property

Office

Application No: Claims searched:

18. An exhaust gas treatment assembly, engine assembly or motor vehicle substantially as described herein, with reference to and as shown in the drawings.

19. A method of operating an exhaust gas treatment assembly substantially as described herein and with reference to the drawings.

Amendments to the Claims have been filed as follows:Claims

a catalyst;

a first position in which the exhaust gases are directed into a sub-portion of the catalyst; and a second position in which the exhaust gases are able to flow into a remaining portion of the catalyst; and an exhaust gas directing element coupled to the catalyst, wherein the exhaust gas directing element is configured to direct exhaust gases passing the movable element towards the sub-portion of the catalyst when the movable element is in the first position.

5. The exhaust gas treatment assembly of any of the preceding claims, wherein the remaining portion of the catalyst is arranged radially outside of the sub-portion of the catalyst.

6. The exhaust gas treatment assembly of any of the preceding claims, wherein the remaining portion of the catalyst is arranged radially outside of the movable element.

7. The exhaust gas treatment assembly of any of the preceding claims, wherein in the second position, the exhaust gases are able to flow into the sub-portion and the remaining portion of the catalyst.

8. The exhaust gas treatment assembly of claim 7, wherein the exhaust gas directing element comprises a fixed tube extending from the catalyst towards the duct.

9. The exhaust gas treatment assembly of any of the preceding claims, wherein a gap is provided between the duct and the movable element.

10. The exhaust gas treatment assembly of claim 9, wherein the assembly further comprises a flow guide provided in the duct, wherein the flow guide is configured to discourage exhaust gases from flowing into the gap.

11. The exhaust gas treatment assembly of any of the preceding claims, wherein the assembly further comprises an actuator configured to control the position of the movable element.

12. An engine assembly comprising the exhaust gas treatment assembly of any of the preceding claims.

13. A motor vehicle comprising the exhaust gas treatment assembly of any of the preceding claims.

a catalyst;

a duct configured to carry exhaust gases from an exhaust pipe to the catalyst; a movable element configured to guide exhaust gases from the duct into the catalyst, wherein the movable element is movable between:

a first position in which the exhaust gases are directed into a sub-portion of the catalyst; and a second position in which the exhaust gases are able to flow into a remaining portion of the catalyst; and an exhaust gas directing element coupled to the catalyst, wherein the exhaust gas directing element is configured to direct exhaust gases passing the movable element towards the sub-portion of the catalyst when the movable element is in the first position, wherein the method comprises: