Field of the Disclosure

The present disclosure relates to components and assemblies for treating exhaust emissions from internal combustion engines. They may be used with such engines which are fuelled by either petrol or diesel, either in vehicles or in static, off-road applications.

The emissions from internal combustion engines are facing ever-increasing scrutiny due to their impact on the environment, particularly in urban areas. Incomplete combustion of diesel fuel produces a variety of particles and gases which, if ingested, may be harmful to health.

Summary of the Disclosure

The present disclosure provides an exhaust emissions treater for insertion in an exhaust gas flow from an internal combustion engine, the treater comprising a rigid body having a reticulated structure. A treater or exhaust emissions treatment component of this form is able to present a large surface area to the gas flow whilst generating a minimal back pressure. The structure may be formed of open cells. It may define tortuous paths for the gas flow from one side of the treater to the other. The reticulated structure may have a high porosity, that is a high proportion of the volume of the structure which is accessible to the exhaust gas. The structure may have a porosity of more than 80% or 85% or more preferably 90% or greater.

The treater may absorb heat energy from exhaust gas flowing through it and then radiate infrared radiation onto particles in the gas flow, causing them to sublime or ablate. Thus, the treater may act as an anti-agglomeration and ablation device in relation to particulate material in the exhaust gases. The reticulated structure may be substantially or solely formed of a metallic or a ceramic material. In a preferred example the reticulated structure is formed of zirconia (or zirconium dioxide) alone. The zirconia is believed to reduce the level of nitrous oxides in the exhaust gas flow.

In further examples, the reticulated structure may comprise a substrate formed of a metallic or ceramic material. The substrate may have a coating which catalyses a reaction that reduces toxic gases and pollutants in the exhaust gas flow into less toxic components. The coating may comprise zirconia and/or ceria-zirconia.

The treater may consist of, or comprise a metallic material which may be a chromium and nickel alloy, or a noble metal, for example. The treater may comprise a ceramic material. The treater may consist of, or comprise a sintered material, which may be a metallic or ceramic material.

The present disclosure further provides an exhaust emissions treater as described herein in combination with an electrically powered heat generator arranged to heat the treater. The heat generator may be used to raise the temperature of the treater. The electrical power fed to the heat generator may be pulsed.

In examples where the treater comprises electrically conductive material, such as a metal, an electric current may be passed through the treater to increase its temperature.

In a system including multiple treaters in combination with respective heat generators, the temperatures of the treaters may be individually controllable. The system may include a controller operable to adjust the respective temperatures of the treaters in response to varying demands on the engine, external weather conditions, changes in the vehicle weight, road conditions and/or local requirements such as low emission zones for example.

The present disclosure also provides a treater assembly comprising an exhaust emissions treater as described herein or such a treater in combination with an electrically powered heat generator, and a tube containing the treater or combination. Furthermore, the present disclosure may provide a treater assembly comprising a tube containing a plurality of treaters or combinations. The tube may be flexible, and formed of metal for example. In use, the tube may be disposed within an exhaust conduit of an engine and act to dissipate vibrations. It may also provide noise attenuation. In preferred examples, the tube is in the form of stripwound tubing which may be manufactured by winding a profiled metal strip in a spiral and interfolding adjacent edges of the strip, to form a tube configuration. Suitable tubing is manufactured by Whitehouse Flexible Tubing Ltd., such as their griplock or interlock tubing, for example.

The tube may be round. Preferably the tube has a polygonal cross-section. The polygonal cross-section may further attenuate vibrations. The tube may have a square or octagonal cross-section. In preferred examples the tube is shaped such that the polygonal cross-section rotates about a central longitudinal axis along the length of the tube.

The tube may be formed of carbon steel or stainless steel for example. The steel may be galvanised. It may be formed of aluminized steel. In examples comprising a plurality of treaters or combinations of treaters and heat generators, at least two of the treaters may have different porosities, or the treaters of at least two of the combinations may have different porosities. Alternatively, or in addition, two or more treaters may have different depths in the direction of gas flow. A downstream treater may have a lower porosity than an upstream treater. It may act to treat relatively small particles passed by a preceding treater. In preferred implementations, a treater swirl generator is located upstream of the treater or series of treaters. The treater swirl generator may comprise a plurality of fixed vanes, angled relative to the direction of gas flow. Rotation of the exhaust gas flow about the flow direction may enhance penetration of the flow into the reticulated structure of the treater. It may enhance ablation of particles in the gas flow by the treater.

Preferably, the treater assembly includes a chamber fluidically coupled in the exhaust gas flow downstream of the treater and an emitter of microwave energy for irradiating a region within the chamber with microwave energy. The emitter may be a microwave antenna. A plurality of such antennae may be provided in the chamber.

A wall of the chamber may be formed by an elongate conduit having an octagonal transverse cross-section which extends around the chamber. The elongate conduit may be in the form of stripwound tubing of the type referred to above.

The treater assembly may include a porous body in the exhaust gas flow path downstream of the treater for reducing the level of nitrogen oxide gases in the exhaust gas flow. The porous body may include a catalyst material which catalyses conversion of nitrogen oxide gases into less harmful substances. The catalyst may comprise a metal oxide, such as iron oxide for example. The porous body may be located in the region of the chamber which is irradiated by energising the emitter of microwave energy. The microwave radiation may serve to activate and/or enhance a catalytic process involving the catalyst material. Provision of a treater upstream of the porous body may prolong the working life of the porous body and reduce build-up of particulate matter thereon.

In a further preferred example, a heater may be included in the exhaust gas flow downstream of the treater and upstream of the chamber and/or the porous body. The heater may serve to raise the temperature of the gas flow in order to reduce the likelihood of any particles in the gas flow from cooling and forming undesirable compounds. Various types of heater may be used. Preferably, it comprises an electrically powered resistive heating element. Furthermore, a heater swirl generator may be provided in the exhaust gas flow downstream of the treater, wherein the heater swirl generator is located upstream of and/or around the heater in a transverse plane with respect to the direction of gas flow. The heater swirl generator acts to increase the length of the gas flow path adjacent to the heater, thereby increasing the ability of the heater to transfer heat energy to the gas flow.

The heater swirl generator may comprise one or more fixed vanes. The or each vane may be helical. The heater swirl generator may be formed of a heat conducting material, such as a metal, and be attached to the heater to assist with conduction of heat energy from the heater to the gas flow by increasing the heated surface area in contact with the gases. The present disclosure may further provide an internal combustion engine including a respective treater, or a respective treater and heat generator combination, or a treater assembly, as described herein, in an exhaust gas flow path from each of a plurality of cylinders of the engine. In such a configuration, the treaters may be located close to the cylinders, and preferably closer than an exhaust manifold. This may mean that the treaters heat up relatively quickly, enabling them to reduce undesirable emissions sooner as the engine warms up. Also, this location may result in the treater having a higher operating temperature during normal running of the engine.

An exhaust gas flow from a cylinder may be divided between two or more tubes, each tube containing a respective treater. In a preferred configuration, the exhaust gas flow from a cylinder is divided between two tubes having a substantially square cross- section. The two square tubes may be arranged parallel to one another, with one side of each tube adjacent to, and preferably in contact with, a side of the other tube. The two tubes may share one side.

Each treater, treater and heat generator combination, or treater assembly may be located upstream of a manifold of the engine which combines exhaust gas flows from a plurality of cylinders of the engine. Alternatively, a respective treater or combination associated with each of a plurality of cylinders may be located within a manifold which combines exhaust gas flows from the cylinders. An additional treater or treater and heat generator combination may be provided downstream of said engine manifold.

In a preferred internal combustion example, at least a portion of the internal surfaces of conduits defining flow paths from each of the cylinders of the engine to the or each treater, combination or treater assembly is coated with a metallic material. For example, at least a portion of these surfaces may be aluminized. Such a coating may reduce spalling.

In further examples, an internal combustion engine may include gas conduits fluidically coupled to the exhaust gas flow path downstream of the treater(s), combination(s) or treater assembly, wherein the gas conduits are arranged to provide exhaust gas recirculation.

Brief Description of the Drawings

Examples of the present disclosure will now be described by way of example and with reference to the accompanying images and schematic drawings, wherein:

Figure 1 is an image including a plurality of treaters according to examples of the disclosure;

Figure 2 is a cross-sectional side view of a treater assembly according to an example of the disclosure;

Figure 3 shows a transverse cross-sectional view of the treater assembly of Figure 2; Figure 4 is an image showing a tube for use in a treater assembly according to an example of the disclosure;

Figure 5 is an image showing an end view of the tube shown in Figure 4; Figure 6 is a diagram showing a cross-sectional view of a manifold of an internal combustion engine according to an example of the disclosure; Figures 7 and 8 are perspective and exploded perspective views, respectively, of an engine cylinder block together with a treater assembly according to an example of the disclosure;

Figure 9 is a perspective cross-sectional view of an engine cylinder block together with a treater assembly according to a further example of the disclosure;

Figures 10 and 11 are perspective cross-sectional views of an engine cylinder block together with a treater assembly according to another example of the disclosure; and Figures 12 to 15 are perspective, exploded and partially cut-away views of a treater assembly according to an additional example of the disclosure.

Detailed Description of the Drawings

Figure 1 shows examples of cylindrical exhaust emission treaters according to the present disclosure. The treaters 2 have a smaller diameter than treater 4.

Each treater in Figure 1 consists of a rigid body having a reticulated structure.

Treaters according to examples of the present disclosure may be formed of ceramic or metallic material. A reticulated ceramic body may be formed by coating a reticulated polyurethane foam with an aqueous suspension of a ceramic powder. The body is then heated to evaporate the water, fuse the ceramic particles, and bum off the polyurethane. Similarly, reticulated metallic structures may also be formed by vapour deposition of the metal on onto a reticulated polyurethane foam and then burning off the polyurethane.

In use, the treaters are preferably located close to the exhaust outlets of an engine block to expose them to a higher temperature when the engine is running. Preferably, the treaters reach a temperature of around 550 to 650°C. Also, close to the engine, it is believed that particulate matter in the exhaust gas flow is at a higher temperature than the gas. In addition, the particles are believed to have not yet agglomerated at this stage to form soot particles. The inventors have found treaters according to the present disclosure to be more effective in treating particulate matter under these conditions, causing the particulate matter to be ablated. Figure 2 shows an example of a treater assembly 10 according to an example of the present disclosure. A cross-sectional view along line A-A is shown in Figure 3. The assembly comprises a series of three cylindrical reticulated treaters 6 located in a tube 8, to form three treatment zones. Each treater extends laterally across the direction of gas flow D along the tube. The outer cylindrical surface of each treater is attached to the tube in a gas-tight manner, so that all of the gas flow passes through each treater in turn. Each treater may be held in position by pins (not shown) extending inwardly from the inner surface of the associated tube.

The tube 8 has an octagonal cross-section, as shown in Figure 3. A suitable tube is shown in Figures 4 and 5. As can be seen in these Figures, the octagonal cross- section rotates along the length of the tube. The tube may be a copper-packed electro- galvanised flexible steel tube formed from an interfolded metal strip, as manufactured by Whitehouse Flexible Tubing Ltd, for example.

The treater assembly 10 is installed in a cylindrical exhaust pipe 12 in Figure 2. The exhaust pipe is coupled to an engine manifold 16. Upstream of the assembly, and downstream of the manifold, a cyclone 14 is mounted in the pipe. The cyclone acts to impart a swirl or rotation to gas flowing in direction D along the pipe 12.

Electrical power is fed to each treater separately via respective wires 16, 18 and 20 for use in increasing the temperature of the treaters. The electrical resistance of the treater itself may be used to generate heat. Alternatively, the wires may be coupled to heating elements. The heating element may extend within the respective treater. Each heating element may comprise heat producing wire or cable.

Another implementation of exhaust emission treaters as described herein in an internal combustion engine is shown in Figure 6. In this configuration, four treaters 30, 32, 34 and 36 are located in an engine exhaust manifold 38. Exhaust outlets 40, 42, 44 and 46 from four respective engine cylinders are fluidically coupled to the manifold to one side of a central longitudinal axis 54 of the manifold. They are spaced apart in a direction parallel to the axis. A manifold outlet port 48 is located on the opposite side of the central axis of the manifold to the exhaust outlets, between the second and third exhaust outlets 42 and 44 in the axial direction. The outlet port 48 is fluidically coupled to an exhaust pipe 50. A further treater 52 is located in the pipe 50 close to outlet port 48.

As shown in Figure 6, the gas flow entering the manifold from each exhaust outlet 40, 42, 44 and 46 impinges on a respective treater 30, 32, 34 and 36. Each treater extends laterally across the manifold. The plane of each treater is angled relative to a central longitudinal axis 54 of the manifold such that each treater extends transversely across the respective exhaust gas inlet with respect to the direction of gas flow from the inlet as it enters the manifold.

A further example of a treater assembly according to the present disclosure is shown in Figures 7 and 8. Figure 7 is a perspective view of an engine cylinder block in combination with the treater assembly and Figure 8 is an exploded view of this configuration.

An engine cylinder block 60 is shown schematically in Figures 7 and 8. It defines four exhaust ports 62 along one side of the block. A treater assembly 64 is fluidically coupled to one of the exhaust ports via a curved tube 66 and a flared connector 68. The connector 68 corresponds to the cross-section of tube 66 at one end and the cross section of the treater assembly 64 at its other end. It will be appreciated that further treater assemblies will be coupled to the other exhaust ports 62 in the same manner in a complete engine.

Treater assembly 64 comprises a pair of tubes 67, each having a square cross-section in a plane perpendicular to their length. The tubes 67 extend parallel to each other, with one side of each tube in contact with one side of the adjacent tube. Each tube contains a respective treater 69 (visible in Figure 8). The transverse cross-section of each treater substantially corresponds to the square cross-section of the inner surface of the associated tube. Figures 9 to 11 show embodiments of a modified treater assembly 64’ which includes a further fluid conduit 70 in the exhaust gas path, downstream of the tubes 67. The conduit 70 defines an elongate chamber that contains a rigid planar porous body 72 or 74.

In the example shown in Figure 9, the porous body 72 extends transversely across the elongate chamber within the conduit. The conduit is shown in cross-section, with the cross-sectional plane passing through the porous body. In an alternative version shown in Figures 10 and 11, the planar porous body 74 extends along the length of the conduit. The exhaust gas flow passes from the tubes 67 into the conduit 70 and then through the porous body 72 or 74 to an output port (not shown) of the chamber, which in turn leads to the vehicle’s exhaust pipe. The chamber may have an output port at one or both ends of the chamber, or partway along the chamber. Further pairs of tubes 67 coupled to other exhaust ports of the engine cylinder block 60 may also be fluidically coupled to the conduit 70, but are omitted from Figures 9 to 11 for the purposes of clarity in the drawings.

A pair of electrical couplings 76 are mounted on the outer surface of the conduit, which are connected to respective antennae that are located within the chamber. This enables signals to be coupled to the antennae to cause them to emit microwave radiation into the chamber. The signals are generated by a source of RF energy located in the vehicle, such as a solid state microwave generator. The porous body includes a catalyst material which catalyses conversion of nitrogen oxide gases into less harmful substances. The catalyst may comprise a metal oxide, such as iron oxide for example. The microwave radiation activates and/or enhances a catalytic process involving the catalyst material. The porous body may include a substrate formed of sintered metal, which may comprise iron, titanium and/or copper for example. The porous body may include zirconia and/or ceria-zirconia. The chamber may contain a plurality of the porous bodies. The or each porous body may be orientated with the plane of the body parallel or perpendicular or at an angle relative to a longitudinal axis of the chamber. A layer of pellets of material may be used instead of the porous body.

In a selective catalytic reduction process, metal oxides may be used to catalyse the conversion of nitrogen oxides into nitrogen and water by a reagent such as ammonia, for example.

Figures 12 to 15 show perspective views of an additional example of a treater assembly 64” according to the present disclosure. In this example, a heating module 80 is included in the exhaust gas flow. It is located downstream of the tubes 67 and upstream of the fluid conduit 70 (of the form shown in Figures 9 to 11 but not included in Figures 12 to 15).

The heating module is included in the exhaust gas flow between the treater tubes 67 and the fluid conduit 70 in order to raise the temperature of the gases before they enter the fluid conduit 70. The heating module serves to counteract cooling of the gases in order to avoid formation of undesirable compounds by any particles in the gas flow.

In the example shown in Figures 12 to 15, the heating module includes an elongate heat source 82 located centrally within a surrounding cylindrical tube 84. Figure 13 shows an exploded view with the heat source removed from the tube and Figures 14 and 15 show the location of the heat source within the tube, with part of the tube cut away for the purposes of illustration. The heat source may be configured to generate temperatures of up to 600°C or more.

The cylindrical tube 84 is fluidically coupled to the treater tubes 67. Only one pair of treater tubes 67 is shown in Figures 12 to 15. It will be appreciated that in practice further pairs of tubes will be coupled to respective exhaust ports 62 at one end and to tube 80 at the other. The cylindrical tube may be formed of a metal such as stainless steel for example. The heat source may comprise a resistive heating element for example. Prills, pellets or micro-briquettes including catalytic material may be provided in the path of the gas flow through the tube ahead of the fluid conduit 70. A helical fin 86 is located between the heat source 82 and the surrounding tube 84. The fin forms a spiral which extends around the heat source and defines a helical gas flow path around the heat source. The fin thereby lengthens the gas flow path adjacent to the heat source and enhances the transfer of heat energy from the heat source to the gases. The fin is attached to the exterior surface of the heat source by welding for example. The outer diameter of the fin may correspond to the inner diameter of the tube 84.