WO1998040610A1

WO1998040610A1 - An engine exhaust system

Info

Publication number: WO1998040610A1
Application number: PCT/GB1998/000730
Authority: WO
Inventors: Trevor John Russell; Simon Christopher Mulqueen
Original assignee: The Associated Octel Company Limited
Priority date: 1997-03-13
Filing date: 1998-03-11
Publication date: 1998-09-17
Also published as: AU6409398A; GB9705208D0

Abstract

An engine exhaust system is described. The engine exhaust system comprises an exhaust manifold (1) operably connectable to an engine; a silencer (3) operably connectable to the exhaust manifold (1); an exhaust pipe (5a) extending from the silencer (3); and an exhaust trap (6) operably connectable to the exhaust pipe (5a), the trap (6) comprising an inlet (10) and an outlet (14b) with an exhaust filter (26) provided therebetween; wherein exhaust from the engine is capable of sequentially flowing from the manifold (1) via the silencer (3) and the exhaust pipe (5a) to the inlet (10) of the exhaust trap (6), then through the exhaust filter means (26) and then through the outlet (14b) of the exhaust trap (6) for the exhaust therefrom, and wherein the exhaust trap (6) is retrofittably securable to the exhaust pipe (5a).

Description

AN ENGINE EXHAUST SYSTEM

The present invention relates to an engine exhaust system.

A known - and typical - engine exhaust system is depicted in Figure 1 (which has been taken from EP-A-0333815). This engine exhaust system comprises an exhaust manifold (1) which is connected by way of a pipe (2) to a silencer (3) and by a further pipe (4) to the exhaust pipe (5a). The various components of the exhaust system of Figure 1 are secured together by conventional clamping devices (5). The manifold is secured to an engine (not shown in Figure 1). Exhaust gases emitted from the engine are thus routed away from the engine and into the atmosphere via a silencer.

As the need for more environmentally friendly engines has arisen, it became desirable to provide an emission control device in an engine exhaust system. Some of these emission control devices were designed to remove pollutants from the exhaust of an operating engine.

An example of an emission control device is an exhaust trap which may be built into the silencer of the exhaust system. Alternatively, and as described in US-A-5189878 the exhaust trap may be provided between the exhaust manifold and the silencer. EP-A-0333815 describes a further variant wherein an exhaust trap is assembled as an integral part of the engine exhaust system. In this regard, the trap may be placed between the exhaust manifold and the silencer or between the silencer and the piece of piping connecting the silencer to the exhaust pipe.

Whilst some of these prior art systems may remove some pollutants from the engine exhaust, they all suffer from similar disadvantages. In this regard, if any of the above traps were to malfunction or were to require cleaning, the engine exhaust system would have to be at least partly disassembled in order to access the trap. Disassembling the engine exhaust system greatly increases the time taken by an individual to replace, repair and/or clean the engine exhaust system and thus also increases the cost of that repair.

The present invention seeks to overcome the problems associated with the known engine exhaust systems.

According to a first aspect of the present invention there is provided an engine exhaust system, comprising: an exhaust manifold operably connected to an engine; a silencer operably connected to the exhaust manifold; an exhaust pipe operably connected to the silencer: an exhaust trap operably connected to the exhaust pipe, the exhaust trap comprising an inlet and an outlet with an exhaust filter provided therebetween; wherein the exhaust trap is retrofittably secured to the silencer; and wherein exhaust gases from the engine are capable of sequentially flowing from the manifold via the silencer and the exhaust pipe to the inlet of the exhaust trap and then through the outlet of the exhaust trap for the exhaust therefrom.

According to a second aspect of the present invention there is provided an exhaust system (optionally in kit form) suitable for use as the engine exhaust system according to the present invention, the exhaust system comprising: an exhaust manifold operably connectable to an engine; a silencer operably connectable to the exhaust manifold; an exhaust pipe operably connected to the silencer: an exhaust trap operably connectable to the exhaust pipe, the exhaust trap comprising an inlet and an outlet with an exhaust filter provided therebetween; wherein the exhaust trap is retrofittably securable to the exhaust pipe; and and wherein exhaust gases from the engine are capable of sequentially flowing from the manifold via the silencer and the exhaust pipe to the inlet of the exhaust trap and then through the outlet of the exhaust trap for the exhaust therefrom.

According to a third aspect of the present invention there is provided an exhaust trap suitable for retrofitting to an engine exhaust system, the exhaust trap comprising an inlet and an outlet with exhaust filter provided therebetween, the exhaust trap being retrofittably securable to an exhaust pipe extending from a silencer, the silencer being operably connected to an engine via an exhaust manifold, such that exhaust gases from the engine are capable of sequentially flowing from the manifold via the silencer and the exhaust pipe to the inlet of the exhaust trap, and then through the outlet of the exhaust trap for the exhaust therefrom.

According to a fourth aspect of the present invention there is provided a process for retrofitting an exhaust trap to an engine exhaust system which comprises an exhaust manifold operably connected to an engine and at least one silencer operably connected to the exhaust manifold and having an exhaust pipe extending therefrom, and wherein the exhaust trap comprises one inlet and one outlet with an exhaust filter provided therebetween: wherein the process comprises the step of fitting the inlet of the exhaust trap to the exhaust pipe so that exhaust gases from the engine are capable of sequentially flowing from the manifold via the silencer and the exhaust pipe to the inlet of the exhaust trap, and then through the outlet of the exhaust trap for the exhaust therefrom.

According to a fifth aspect of the present invention there is provided the use of any one of the engine exhaust system according to the present invention or the exhaust system according to the present invention or the exhaust trap according to the present invention to remove lead particulates from an engine exhaust gas.

Preferably the exhaust filter comprises any one or more of a ceramic monolith, sintered metal, fused silica wool, stainless steel, extruded alumina foam, compressed or fluted fabric.

Preferably the exhaust filter comprises a coating of activated alumina.

Preferably the exhaust filter has been coated in-situ.

Preferably the activated alumina is derived from an alumina slurry.

Preferably the exhaust filter is provided within a housing. Preferably the housing comprises a first portion having the inlet provided therein and an end cap releasably securable to the first portion, the end cap having the outlet provided therein and the exhaust filter secured thereto about the outlet.

Preferably the first portion comprises a base having the inlet provided therein and an peripheral wall extending substantially perpendicularly from the base, an end portion of the peripheral wall furthest from the base having a flange extending parallel to the base and towards the inlet, the flange being capable of having the end cap secured thereto.

Preferably the end cap comprises a planar base portion having the outlet provided therein, a tubular member closed at one end extending through the outlet to either side of the base portion, the closed end of the tubular portion having a cover member releasably secured thereto, the cover member comprising a cover base with a flanged periphery and a cover tube secured to the base within the flanged periphery and sized to as to fit over the tubular member, the end of the cover tube furthest from the cover base being flanged thereby to form a cavity within which the exhaust filter is provided, the cavity being bounded on one side by the cover tube, at one end by the cover base and peripheral flange and at the other end by the cover member flange.

The present invention has a number of advantages. For example, the trap of the present invention may be easily and quickly fitted. In addition, the trap of the present invention may be easily and quickly removed for servicing, repair, replacement or cleaning. Furthermore, the trap utilised in the engine exhaust system of the present invention is ideally suited for retrofitting to existing engine exhaust systems that do not comprise a trap. The trap of the present invention also exhibits efficient pollutant removal, particularly when the pollutant is a particulate pollutant.

Moreover, the present invention is particularly suited for removing lead particulates from engine exhaust gases. This result was highly surprising. Hence, an advantageous use of the engine exhaust system of the present invention is reducing lead particulates from the exhaust of vehicles operating on leaded gasoline. When the exhaust gases from the engine sequentially flow from the manifold via the silencer to the inlet of the at least one trap and then through the at least one outlet of the at least one trap for the exhaust therefrom, the exhaust gases flow though, over or on (including combinations thereof) the filter.

Even though the present invention is particularly suited for use as an exhaust system for an internal combustion engine (ICE), it is to be noted that the present invention is not limited to ICEs and that it may be used with any form of engine. In addition, the present invention may be employed as a paniculate trap for use with diesel ICEs or with petrol ICEs.

The engine exhaust system can comprise a plurality of manifolds and/or silencers and/or exhaust pipes and/or inlets and/or outlets.

The present invention will now be described by way of example only and with reference to the accompanying Figures:

Figure 1 is a schematic diagram of a previously proposed exhaust system;

Figure 2 is a schematic diagram of an exhaust system according to the invention;

Figure 3 is a schematic cross sectional view of a trap suitable for use in the system of Figure 2;

Figure 3a is a cross sectional view along the line a— a in Figure 3;

Figure 4 illustrates an alternative means for attaching the trap of Figure 3 to the system of Figure 2;

Figure 5 is a schematic cross sectional view of another trap suitable for use with the system of Figure 2; Figure 5a is a cross-sectional view along the line a— a in Figure 5;

Figure 6 is a schematic cross sectional view of another trap;

Figure 6a is a cross sectional view along the line a— a in Figure 6;

Figure 7 is a schematic cross sectional view of another trap suitable for use with the system of Figure 2;

Figure 7a is a cross sectional view along the line a— a in Figure 7;

Figure 8 is a schematic cross sectional view of another trap suitable for use with the system of Figure 2; and

Figures 8a and 8b are cross sectional views along the lines a— a and b— b, respectively, in Figure 8.

Figure 1 shows a previously proposed exhaust system. Figure 1 was taken from EP-A-0333815. The exhaust system comprises an exhaust manifold 1 connected to one end of a silencer 3 by way of a pipe 2 and an exhaust pipe 4 which is connected to the other end of the silencer 3. Exhaust sequentially flows away from an engine (not shown) via the manifold 1, the pipe 2, the silencer 3, the pipe 4 and the exhaust pipe 5a.

As shown in Figure 2, the exhaust system of the present invention comprises a trap 6 retrofitted to the exhaust pipe 5a. The various components of the exhaust system of Figure 2 may be secured together by conventional clamping devices 5. The trap 6 may even comprise an integral exhaust pipe 6a extending away from the trap 6.

Figure 3 shows a first embodiment of a trap 6 suitable for use with the system of Figure 2. As shown, an inlet 10 of the trap 6 is connected to an exhaust pipe 5a extending from the silencer 3. It will be appreciated that the exhaust pipe 5a may be longer or further piping may be introduced between the silencer and the exhaust pipe if needed. The trap inlet 10 is secured to the exhaust pipe 5a by way of a conventional pipe clamp 5. The inlet 10 of the trap may extend over the exhaust pipe 5a or, alternatively, the inlet 10 of the trap may extend within the exhaust pipe 5a.

The trap comprises a housing 12 having a base 12a and a peripheral wall 12b extending perpendicularly from the base 12a. One end of the peripheral wall is provided with a flange 12c.

An end cap 14 is releasably secured to the housing flange 12c by nuts and bolts 16. The end cap 14 comprises a base 14a with an outlet 14b provided therein. A tube 18, optionally closed at the end nearest to the exhaust pipe 3a, extends on either side of the base 14a through the outlet 14b. One end of the tube 18 is provided with a plurality of apertures 20 therein which allow exhaust gasses to pass from the interior of the housing 12 to the outlet 14b.

A cover member 22 is releasably attached to one end of the tube 18. The cover member 22 comprises a base 22a with a peripheral flange 22b. A cover tube 22c is mounted on the base 22a within the peripheral flange 22b. The cover tube is sized so as to fit over the tube 18. The cover tube 22c is provided with a flange 22d at the end of the tube furthest from the cover base 22a. The cover base 22a, peripheral flange 22b, cover tube 22c and flange 22d together define a cavity 24 which is open at one side. A filter member 26 is provided and retained within the cavity 24.

The filter member may be a ceramic filter, a sintered metal filter, a fused silica wool filter, a stainless steel wool filter, an extruded alumina foam filter or a compressed or fluted fabric filter. Optionally, some of these filters (eg the ceramc, sintered metal, silica wool or steel wool filters) may be coated with activated alumina by an in-situ process within the housing or by the application of alumina slurry. The stainless steel wool may be packed to a density of between substantially 50 grammes per litre to substantially 1000 grammes per litre. A variety of suitable other materials may also be used alone or in combination with the materials just mentioned. For example, impregnating alumina with a phosphate wash leads to improved fixing of volatile lead halides.

Operation of the engine in use causes exhaust gases to be driven from the engine, and then sequentially through the exhaust manifold 1, the silencer 3, the exhaust pipe 5a, and the inlet 10 of the trap 6. The exhaust then flows through the filter member 26 and the apertures 20 in the tube 22c and finally, out of the exhaust system via the outlet 14b.

Figure 3a shows a cross sectional view along the line a— a of Figure 3 and illustrates a preferred arrangement where the end cap 14 is secured to the flanges 12c by four bolts 16 spaced at substantially ninety degree intervals around the periphery of the end cap base 14a. It will be apparent that this arrangement enables the end cap 14 to be easily removed from the trap 6 so that the trap filter can be easily replaced or cleaned.

Figure 4 illustrates an alternative means for attaching the trap of Figure 3 to the system of Figure 2. In this embodiment, the clamping device 5 comprises a pair of wing screw clips which engage with a silicon rubber hose to clamp the inlet 10 to the exhaust pipe 5a.

Figure 5 is a schematic cross sectional view of another trap suitable for use with the system of Figure 2. All of the components of the trap 6 are similar to those shown in Figure 3 and are similarly referenced in Figure 5.

As shown in Figure 5, and more clearly in Figure 5a. the filter member 26 has been pleated so that the surface area of filter exposed to the interior of the housing - and hence the engine exhaust - is increased. This arrangement provides an increase in the operating efficiency of the trap 6.

Figure 5a is a cross-sectional view along the line a— a in Figure 5 showing in more detail the particular arrangement of the filter member 26. This filter arrangement is particularly suited for fabric filters that may also be compressed. It will be apparent however that a variety of other materials may be used instead.

Figure 6 is a schematic cross sectional view of another trap which may be fitted to high performance vehicles that are provided with, for example, a dual exhaust.

As shown, the arrangement of Figure 6 comprises a larger housing that is provided with two inlets 10, two outlets 14b and two sets of filter members 26. In all other respects the construction of the individual components of the trap are similar to those of earlier figures and thus, need not be described further herein. Of course, a larger number of filter members and associated outlets 14b and inlets 10 may be provided if desired. Figure 6a is a cross sectional view along the line a— a in Figure 6.

Figure 7 is a schematic cross sectional view of another trap suitable for use with the system of Figure 2. In this embodiment, the trap 6 comprises a housing 12 which is similar to that of the earlier figures. The housing 12 has an inlet 10 and an outlet 30. A filter member 26 is provide inside the housing 12. The filter member may be made from any of the filter materials described above, or, alternatively, the filter member may be manufactured from a sintered metal that may be optionally coated with activated alumina in an in-situ process or by the application of alumina slurry. Figure 7a is a cross sectional view along the line a— a in Figure 7.

Figure 8 is a schematic cross sectional view of another trap suitable for use with the system of Figure 2. The components of the trap 6 are identical to those shown in Figure 7 and thus need not be further described. However, in this embodiment, the filter member 26 comprises a ceramic body which, once again, may be coated with activated alumina in an in-situ process or by the application of alumina slurry. Figure 8a is a cross sectional view along the line a— a of Figure 8 showing the layout of the ceramic body. Figure 8b is a cross sectional view along the line b— b in Figure 8.

The present invention therefore provides an improved and advantageous emission control device. In the exhaust system of the present invention the exhaust gases can be dispersed into the atmosphere directly on leaving the outlet of the exhaust trap. Alternatively, the exhaust gases need not necessarily be dispersed into the atmosphere directly on leaving the outlet of the exhaust trap. For example, the exhaust gases can be dispersed into the atmosphere via a pipe that is connected to the outlet of the exhaust trap.

EXAMPLE

Two exhaust gas filter designs have been evaluated on European vehicle models with 2.01 engines. The designs tested were of the type illustrated in figures 6 and 7. Figure 6 is termed a twin radial filter (26), and figure 7 an axial filter (26). These designs were fitted to the tailpipe of each vehicle's existing exhaust system.

The vehicle's were fuelled with a leaded gasoline meeting BS4040 specifications, at a lead level of 0.15g Pb/litre. Evaluation of the filters (26), in terms of their lead catchment efficiency, was performed on a chassis dynamometer, over a specified driving cycle of known distance. The amount of elemental lead found to be emitted from the tailpipe, over this test interval, is expressed as a percentage of the calculated elemental lead entering the vehicle. This testing was performed immediately after the installation of the filter (26) and again after distance accumulation of 8,000km, on leaded gasoline.

The analysis demonstrated that at the beginning of testing, with the axial (26) and twin radial (26) filters fitted. 4% and 6% of the input lead was emitted from the tailpipe of the respective vehicles. After distance accumulation of 8.000km, a repeat of the lead emission analysis, confirmed continued efficient operation of the filters. The percentage of input lead emitted from the tailpipe of the two vehicles being 4 % and 8% for the axial (26) and twin radial (26) filters respectively.

Other modifications of the present invention will be apparent to those skilled in the art.

Claims

1. An engine exhaust system, comprising:

an exhaust manifold operably connected to an engine;

a silencer operably connected to the exhaust manifold;

an exhaust pipe operably connected to the silencer;

an exhaust trap operably connected to the exhaust pipe, the exhaust trap comprising an inlet and an outlet with an exhaust filter provided therebetween;

wherein the exhaust trap is retrofittably secured to the silencer;

and wherein exhaust gases from the engine are capable of sequentially flowing from the manifold via the silencer and the exhaust pipe to the inlet of the exhaust trap and then through the outlet of the exhaust trap for the exhaust therefrom.

2. An engine exhaust system according to claim 1 , wherein the exhaust filter comprises any one or more of a ceramic monolith, sintered metal, fused silica wool, stainless steel, extruded alumina foam, compressed or fluted fabric.

3. An engine exhaust system according to claim 1 or claim 2, wherein the exhaust filter comprises a coating of activated alumina.

4. An engine exhaust system according to claim 3, wherein the exhaust filter has been coated in-situ.

5. An engine exhaust system according to claim 3 or claim 4, wherein the activated alumina is derived from an alumina slurry.

6. An engine exhaust system according to any of claims 1 to 5, wherein the exhaust filter is provided within a housing.

7. An engine exhaust system according to claim 6. wherein the housing comprises a first portion having the inlet provided therein and an end cap releasably securable to the first portion, the end cap having the outlet provided therein and the exhaust filter secured thereto about the outlet.

8. An engine exhaust system according to claim 7, wherein the first portion comprises a base having the inlet provided therein and an peripheral wall extending substantially perpendicularly from the base, an end portion of the peripheral wall furthest from the base having a flange extending parallel to the base and towards the inlet, the flange being capable of having the end cap secured thereto.

9. An engine exhaust system according to claim 7 or claim 8, wherein the end cap comprises a planar base portion having the outlet provided therein, a tubular member closed at one end extending through the outlet to either side of the base portion, the closed end of the tubular portion having a cover member releasably secured thereto, the cover member comprising a cover base with a flanged periphery and a cover tube secured to the base within the flanged periphery and sized to as to fit over the tubular member, the end of the cover tube furthest from the cover base being flanged thereby to form a cavity within which the exhaust filter is provided, the cavity being bounded on one side by the cover tube, at one end by the cover base and peripheral flange and at the other end by the cover member flange.

10. An exhaust system (optionally in kit form) suitable for use as the engine exhaust system according to any one of claims 1 to 9, the exhaust system comprising:

an exhaust manifold operably connectable to an engine;

a silencer operably connectable to the exhaust manifold; an exhaust pipe operably connected to the silencer;

an exhaust trap operably connectable to the exhaust pipe, the exhaust trap comprising an inlet and an outlet with an exhaust filter provided therebetween;

wherein the exhaust trap is retrofittably securable to the exhaust pipe; and

11. An exhaust trap suitable for retrofitting to an engine exhaust system, the exhaust trap comprising an inlet and an outlet with exhaust filter provided therebetween, the exhaust trap being retrofittably securable to an exhaust pipe extending from a silencer, the silencer being operably connected to an engine via an exhaust manifold, such that exhaust gases from the engine are capable of sequentially flowing from the manifold via the silencer and the exhaust pipe to the inlet of the exhaust trap, and then through the outlet of the exhaust trap for the exhaust therefrom.

17. A process for retrofitting an exhaust trap to an engine exhaust system which comprises an exhaust manifold operably connected to an engine and at least one silencer operably connected to the exhaust manifold and having an exhaust pipe extending therefrom, and wherein the exhaust trap comprises one inlet and one outlet with an exhaust filter provided therebetween; wherein the process comprises the step of fitting the inlet of the exhaust trap to the exhaust pipe so that exhaust gases from the engine are capable of sequentially flowing from the manifold via the silencer and the exhaust pipe to the inlet of the exhaust trap, and then through the outlet of the exhaust trap for the exhaust therefrom.

13. The use of the invention according to any one of claims 1 to 12 to remove lead particulates from an engine exhaust gas.

14. An engine exhaust system substantially as hereinbefore described and with reference to Figures 2 to 8b of the accompanying drawings.

15. An exhaust system substantially as hereinbefore described and with reference to Figures 2 to 8b of the accompanying drawings.

16. An exhaust trap substantially as hereinbefore described and reference to any one of Figures 2 to 8b of the accompanying drawings.

17. A kit substantially as hereinbefore described and with reference to Figures 2 to 8b of the accompanying drawings.