WO2004076830A1

WO2004076830A1 - Exhaust system

Info

Publication number: WO2004076830A1
Application number: PCT/GB2004/000821
Authority: WO
Inventors: Trevor Lee Fletcher; Stephen David Storrar
Original assignee: T Baden Hardstaff Limited
Priority date: 2003-02-28
Filing date: 2004-03-01
Publication date: 2004-09-10
Also published as: PL1601863T3; PT1601863E; GB0304629D0; EP1601863B1; ATE526494T1; ES2392829T3; SI1601863T1; DK1601863T3; EP1601863A1

Abstract

An exhaust system (10) for an engine system, the exhaust system (10) comprising a pipe system (12) having at least one input port (15, 16) for receiving exhaust gases from the engine (14) system and at least one output port (18) for venting exhaust gases from the exhaust system (10) wherein the pipe system (12) includes at least two exhaust routes for flow of gases from the one or more input ports (15, 16) to the one or more output ports (18), and further includes a diverter valve (28) operable in response to a control input to control the flow of exhaust gases through the pipe system (12) through one or more of the exhaust routes, the diverter valve (28) comprising at least two butterfly valve members (36), each butterfly valve member (36) controlling the flow of exhaust gases via one of said exhaust routes, each member having an input face (21) and an output face (23), at least one input face (21) comprising input disrupting means (50) for disrupting the flow of exhaust gases emitted from the engine (14) system.

Description

EXHAUST SYSTEM

The invention relates to an exhaust system for use with an engine system and, in particular, relates to an exhaust system for a dual fuel engine system.

EU regulations require engine emissions to meet particular standards in terms of the types and quantities of gases emitted. Engine emissions ^"depend on may factors including the type and amount of fuel injected into the engine for combustion, and post combustion gas treatment.

In dual fuel engines where the delivery of diesel fuel and gas fuel is controlled by one or more engine computers, it is important to control the amount of methane contained in exhaust gases.

In order to assess the efficiency and effectiveness of a proposed exhaust gas management system, or to assess the efficiency and effectiveness of an existing exhaust gas management system, it is necessary to make comparative measurements.

According to a first aspect of the invention there is provided an exhaust system for an engine system, the exhaust system comprising a pipe system having at least one input port for receiving exhaust gases from the engine system and at least one output port for venting exhaust gases from the exhaust system wherein the pipe system includes at least two exhaust routes for flow of gases from the one or more input ports to the one or more output ports, and further includes a diverter valve operable in response to a control input to control the flow of exhaust gases through the pipe system through one or more of the exhaust routes, the diverter valve comprising at least two butterfly valve members, each butterfly valve member controlling the flow of exhaust gases via one of said exhaust routes, each member having an input face and an output face, at least one input face comprising input disrupting means for disrupting the flow of exhaust gases emitted from the engine system.

The terms "input face" and "output face" used to describe the butterfly valve members, refer to the orientation of the faces of the butterfly valve member when that member is in the closed position. When a butterfly valve member is in the closed position, it will have one face that is directed towards an input port, which face has been described as the input face, and a face that is directed towards an output port, which face has been described as an output face.

It is to be understood, however, that when a butterfly valve member is in an open position, its faces will no longer be so orientated, and will instead take up a position approximately perpendicular to the position of the faces in the closed position.

The provision of a diverter valve provides an effective arrangement for enabling the efficiency and effectiveness of a particular exhaust gas management system to be assessed. This is because the diverter valve enables the flow of exhaust gases from an engine to be directed along one of at least two exhaust routes. It is therefore possible to compare the efficiency and effectiveness of at least two exhaust arrangements using the same engine. This enables a more accurate and consistent comparison of the two arrangements to be made. For example, it is possible to compare an exhaust arrangement including a catalyst treatment system with an exhaust arrangement excluding a catalyst, or to directly compare the efficiency of different catalysts. The provision of the diverter valve in the pipe system also enables effective measurements to be made by diverting the exhaust gases to a sensor chamber without affecting the flow of exhaust gases through the exhaust system.

The input disrupting means creates disruption in the flow of exhaust gases, and thus disrupts laminar exhaust gas flow. Further, the disruption of laminar flow allows the exhaust gases to expand which results in a more even distribution of exhaust gases.

The disruption means may cause either turbulence in the exhaust gases, or may induce a swirling motion in the exhaust gases.

A turbulent flow is generally regarded as being fluid flow in which the particle motion of the fluid at any point varies rapidly in magnitude and direction. This results in irregular eddy motion. On the other hand, a swirling motion is one in which the particle motion is substantially helical, and will have either a clockwise or counter-clockwise sense.

When the exhaust system further comprises a catalyst treatment system comprising a catalyst having an exposed face, in at least one of the exhaust routes, the diverter valve causes a more even distribution of exhaust gases over the exposed face of the catalyst.

In known exhaust systems, it is known that high speed gases emitted from the engine tend to form a path through the centre of the core of a catalyst, and do not spread across the entire exposed face of the catalyst. This results in the outer perimeter of the catalyst receiving a disproportionately low flow of exhaust gases. This in turn leads to inefficiencies in the catalytic conversion of the exhaust gases. Advantageously, the input disrupting means comprises one or more blades formed on the at least one input face.

Preferably, the diverter comprises walls associated with each butterfly member, the walls associated with at least one of the butterfly members being convex. The convex walls form a venturi, and in combination with the disruptive means further improves the even distribution of exhaust gases across the face of a catalyst positioned in one of the exhaust routes, thereby improving the efficiency of the catalytic conversion.

Advantageously, at least one output face comprises outputdisrapting means for creating turbulence in exhaust gases.

Preferably, the output disrupting means comprises one or more blades formed on the at least one output face.

Other advantageous features of the invention will become apparent from dependent Claims 2-27.

According to a second aspect of the present invention, there is provided a diverter valve comprising at least two butterfly valve members, each member having a first face, and an opposite face, at least one of the first faces comprising disrupting means for disrupting the flow of fluids passing through the valve.

According to a third aspect of the present invention, there is provided an engine system including an engine, and an exhaust system comprising a pipe system having at least one input port for receiving exhaust gases from the engine system and at least one output port for venting exhaust gases from the exhaust system wherein the pipe system includes at least two exhaust routes for flow of gases from the one or more input ports to the one or more output ports, and further includes a diverter valve operable in response to a control input to control the flow of exhaust gases through the pipe system through one or more of the exhaust routes, the diverter valve comprising at least two butterfly valve members, each butterfly valve member controlling the flow of exhaust gases via one of said exhaust routes, each member having an input face and an output face, at least one input face comprising input disrupting means for disrupting the flow of exhaust gases emitted from the engine system.

Embodiments of the invention will now be described, by way of non- limiting examples, with reference to the accompanying drawings in which:

Figure 1 is a schematic illustration of an exhaust system according to an embodiment of the invention;

Figure 2 is a schematic illustration of an exhaust system according to another embodiment of the invention;

Figure 3 is a schematic illustration of an exhaust system according to a yet further embodiment of the invention;

Figures 4a-4d show a diverter valve of the exhaust systems of Figures 1-3; and

Figures 5, 6a and 6b illustrate a diverter valve forming part of the invention.

An exhaust system 10 according to an embodiment of the invention is shown in Figure 1. The exhaust system 10 includes a pipe system 12 connected to the exhaust of an engine 14. The pipe system 12 includes two input ports 15,16 for receiving exhaust gases from the engine 14.

The pipe system also includes an output port 18 for venting exhaust gases from the exhaust system 10.

One of the input ports 15 of the pipe system 12 is defined by one end of a catalyst treatment system 20. The catalyst treatment system 20 includes a pre-catalyst 22 and a main catalyst 24 connected in series. The catalyst treatment system 20 defines a first exhaust route A through the pipe system 12 for exhaust gases from the engine 14, and is connected at its other end to an input pipe 26 of a diverter valve 28.

The other of the input ports 16 of the pipe system 12 is defined by one end of a bypass pipe 30. The bypass pipe 30 defines a second exhaust route B through the pipe system 12 for exhaust gases from the engine 14, and is connected at its other end to a second input pipe 32 of the diverter valve 28.

The two input pipes 26,32 of the diverter valve 28 merge into a single output pipe 34.

Each of the input pipes 26,32 includes a butterfly valve member 36 defined by a circular disc 38 (Figures 4a and 4b) pivotally mounted within the respective pipe 26,32 such that it is movable between an open position 0_P and a closed position 0< Each of the circular discs 38 corresponds in diameter to the internal diameter of the respective pipe 26,32 such that when the butterfly valve member 36 is moved to its closed position O_c, it blocks the flow of gas through the pipe. The butterfly valve members 36 are pivotally mounted on a common spindle 40 at an angle of 90° to each other. This ensures that when one of the valve members 36 is in its open position 0_P, the other of the valve members 36 is in its closed position O_c, thereby ensuring that one of the valve members 36 is always open. Failure of the engine system, through blockage of the flow of exhaust gases through the exhaust system 10, is thereby prevented.

The spindle 40 is rotatably mounted in the body 42 of the diverter valve 28 defined by the input and output pipes 26,32,34, and is connected to a solenoid 44 mounted on the body 42 (see Figures 4c and 4d) to control rotation of the spindle 40 in the body 42.

The solenoid 44 is preferably controlled by a switch (not shown) such as, for example, an electronic switch. The switch may be operated directly, or it may include a receiver (not shown) to receive signals from a transmitter and permit control of the switch, and therefore the solenoid 44, from a remote location.

The exhaust route A,B taken by exhaust gases from the engine 14, through the pipe system 12, is determined by the relative orientation of the butterfly valve members 36 in the diverter valve 28. For example, when the butterfly valve member 36 in the first input pipe 26 is in its open position Op, exhaust gases from the engine 14 pass through the catalyst treatment system 20. Similarly, when the butterfly valve member 36 in the second input pipe 32 is in its open position 0_P, exhaust gases from the engine 14 pass through the bypass pipe 30. The output pipe 34 of the diverter valve 28 is connected to an input pipe 45 of a continuously regenerating trap 46, which in turn is connected to an exhaust outlet pipe 48 defining the output port 18 of the pipe system 12.

The continuously regenerating trap 46 separates non-compliant emission particulates from exhaust gases passing therethrough.

An exhaust gas sensor 50a,50b is preferably provided in the bypass pipe 30 and in the catalyst treatment system 20, downstream of the main catalyst 24, to identify and measure the quantities of one or more gases in the exhaust gases.

The type of sensor 50a,50b installed in the bypass pipe 30 and the catalyst treatment system 20 is determined by the fuel used in the engine 14 connected to the exhaust system 10. For example, in a dual fuel engine using gas and diesel, the sensor 50a,50b is preferably a methane sensor to determine the quantity of methane contained in the exhaust gases.

The provision of a sensor 50a,50b in each of the exhaust routes A,B provides means for analyzing exhaust gases passing through each of the routes, and thereby permits comparative measurements to be made. It therefore enables the efficiency and effectiveness of the catalyst treatment system 20 to be compared with that of a simple bypass pipe 30 having no catalyst.

It is envisaged that the diverter valve 28 will permit comparison of the two routes under different engine loading conditions simply by operating the solenoid 44 to vary the exhaust route A,B through the pipe system 12 which is taken by exhaust gases emitted by the engine 14. The exhaust gas outlet pipe 48 preferably includes an exhaust gas sensor 52.

This allows the content of exhaust gases emitted into the atmosphere from the outlet pipe 48 to be monitored.

As with the sensor 50a,50b installed in each of the bypass pipe 30 and the catalyst treatment system 20, the particular type of sensor 52 installed in the exhaust gas outlet pipe 48 is determined by the fuel used in the engine 14 connected to the exhaust system 10. For example, in a dual fuel engine using gas and diesel, the sensor 52 is preferably a methane sensor to determine the quantity of methane contained in the exhaust gases.

The sensors 50a,50b,52 provided in the exhaust system 10 may include transmitters which permit the sensors 50a,50b,52 to transmit measurements to a central control unit (not shown). The control unit may then use the measurements to control the diverter valve 28 and/or control the fuel injection in the engine 14.

In other embodiments, the diverter valve 28 may be reversed and positioned between the engine 14 and the exhaust routes A,B. In such embodiments, the exhaust of engine 14 is connected to pipe 34 of the diverter valve 28, the catalyst treatment system 20 is connected to pipe 26 and the bypass pipe 30 is connected to pipe 32. Both the catalyst treatment system 20 and the bypass pipe 30 are connected at their other ends to the input pipe 45 of the continuous regenerating trap 46. Again the relative positions of the butterfly valve members 36 in the diverter valve 28 determine which exhaust route A,B is taken by exhaust gases emitted by the engine 14. An exhaust system 60 according to another embodiment of the invention is shown in Figure 2. The same reference numerals are used to identify parts similar to those described with reference to Figure 1.

As in the embodiment described with reference to Figure 1, the exhaust system 60 includes a pipe system 12 connected to the exhaust of an engine 14. In this embodiment, however, the pipe system 12 includes a single input port 115 for receiving exhaust gases from the engine 14.

The pipe system 12 also includes an output port 18 for venting exhaust gases from the exhaust system 60.

The input port 115 of the pipe system 12 is defined by an input pipe 34 of the diverter valve 28. The input pipe 34 of the diverter valve 28 splits to form two output pipes 26,32.

One of the output pipes 26 is connected to one end of a catalyst treatment system 120 including a pre-catalyst 122 and a main catalyst 124 connected in series. The catalyst treatment system 120 defines a first exhaust route A through the pipe system 12 for exhaust gases from the engine 14, and is connected at its other end to an input pipe 45 of a continuous regenerating trap 46.

The other output pipe 32 is connected to one end of another catalyst treatment system 220 including a pre-catalyst 222 and a main catalyst 224 connected in series. The second catalyst treatment system 220 defines a second exhaust route B through the pipe system 12 for exhaust gases from the engine 14, and is connected at its other end to the input pipe 45 of the continuous regenerating trap 46. The continuous regenerating trap 46 is connected to an exhaust outlet pipe 48 defining the output port 18 of the exhaust system 60.

In a similar manner to the embodiment described with reference to Figure 1, each of output pipes 26,32 of the diverter valve 28 includes a butterfly valve member 36 movable between an open position 0_P and a closed position Oc (Figures 4a and 4b).

The mounting and operation of the butterfly valve members 36 in the diverter valve 28 of the exhaust system 60 is essentially identical to that described with reference to the exhaust system 10 shown in Figure 1.

The exhaust route A,B taken by exhaust gases from the engine 14, through the pipe system 12, is determined by the relative orientation of the butterfly valve members 36 in the diverter valve 28. For example, when the butterfly valve member 36 in the first output pipe 26 is in its open position Op, exhaust gases from the engine 14 pass through the first catalyst treatment system 120. Similarly, when the butterfly valve member 36 in the second output pipe 32 is in its open position Op, exhaust gases from the engine 14 pass through the second catalyst treatment system 220.

An exhaust gas sensor 150 is preferably provided downstream of the main catalysts 124,224 to identify and measure the quantities of one or more gases in the exhaust gases. The sensor 150 may include a single sensor located in the input pipe 45 of the continuous regenerating trap 46. Alternatively, the sensor 150 may include a separate sensor in each of the first and second catalyst treatment systems 120,220.

The type of sensor 150 is determined by the fuel used in the engine 14 connected to the exhaust system 60. For example, in a dual fuel engine using gas and diesel, the sensor 150 is preferably a methane sensor to determine the quantity of methane contained in the exhaust gases.

The provision of a sensor 150 provides means for analyzing exhaust gases passing through each of the routes A,B, and thereby permits comparative measurements to be made. It therefore enables the efficiency and effectiveness of the first catalyst treatment system 120 to be compared with that of the second catalyst treatment system 220.

It is also envisaged that the diverter valve 28 will make it possible to increase the lifetime of the exhaust system 60 by enabling the provision of two catalyst treatment systems 120, 220 which can be switched between.

In particular, if one of the catalyst treatment system 120, 220 is not working efficiently enough, the butterfly valve member controlling the flow of exhaust gases through the route in which that catalyst treatment system is located may be closed, thus diverting all exhaust gases through the other of the two exhaust routes to ensure that all gases are treated by the other catalyst treatment system.

The exliaust gas outlet pipe 48 preferably includes an exhaust gas sensor 152.

As with the sensor 150 installed in each of the first and second catalyst treatment systems 120,220, the particular type of sensor 152 installed in the exhaust gas outlet pipe 48 is determined by the fuel used in the engine 14 connected to the exhaust system 60. For example, in a dual fuel engine using gas and diesel, the sensor 152 is preferably a methane sensor to determine the quantity of methane contained in the exhaust gases.

The sensors 150,152 provided in the exhaust system 10 may include transmitters which permit the sensors 150,152 to transmit measurements to a central control unit 62. The control unit 62 may then use the measurements to control the diverter valve 28 and/or control the fuel injection in the engine 14.

The control unit 62 is preferably linked to a remote control computer 64 so that performance of the exhaust system 60 may be monitored from a remote location.

In arrangements where the engine 14 is a dual fuel engine, information from engine sensors may be passed to a diesel control module 66 and information from gas sensors may be passed to a gas control module 68. On the basis of this information, the diesel and gas control modules 66,68 may communicate with each other and control the diesel and gas injectors on the basis of the combined information.

In other embodiments, the exhaust system may comprise a single control module for controlling both the diesel and the gas injector.

Information from the diesel and gas control modules 66,68 may also be passed to a cab display module 70 within the vehicle together with information acquired from other components in the vehicle. This enables the vehicle operator to monitor the performance of the engine. This vehicle and/or engine information may also be passed to the control unit 62 to assist it in controlling the diverter valve 28. It may also, in turn, be passed to the remote control computer 64.

An exhaust system 80 according to a yet further embodiment of the invention is shown in Figure 3. Again the same reference numerals are used to identify similar components.

In this embodiment, which is particularly advantageous for use with a dual fuel engine 14, the exhaust system 80 includes a pipe system 12 connected to the exhaust of an engine 14. As with the embodiment described with reference to Figure 2, the pipe system 12 includes a single input port 115 for receiving exhaust gases from the engine 14.

The pipe system 12 also includes an output port 18 for venting exhaust gases from the exhaust system 80.

The input port 115 of the pipe system 12 is defined by one end of a catalyst treatment system 320 including a pre-catalyst 322 and a main catalyst 324 connected in series.

The catalyst treatment system 320 is connected at its other end to an input pipe 34 of the diverter valve 28. The input pipe 34 of the diverter valve 28 splits to form two output pipes 26,32.

One of the output pipes 26 is connected to an input pipe 82 of a chamber 84. Input pipe 82 and chamber 84 define a first exhaust route A through the pipe system 12 for exhaust gases from the engine 14. The chamber 84 includes an open valve (not shown) which allows the controlled release of exhaust gases directed to the chamber 84, and thereby defines an output port 18a of the exhaust system 80. The chamber 84 also includes a methane sensor 86.

The other output pipe 32 is connected to an exhaust outlet pipe 88. The exhaust outlet pipe 88 defines a second exhaust route B through the pipe system 12 for exhaust gases from the engine 14, and defines an output port 18b of the exhaust system 80.

In a similar manner to the embodiments described with reference to Figures 1 and 2, each of output pipes 26,32 of the diverter valve 28 includes a butterfly valve member 36 movable between an open position Op and a closed position Oc (Figures 4a and 4b).

The mounting and operation of the butterfly valve members 36 in the diverter valve 28 of the exhaust system 80 is essentially identical to that described with reference to the exhaust systems 10,60 shown in Figures 1 and 2.

The exhaust route A,B taken by exhaust gases from the engine 14, through the pipe system 12, is determined by the relative orientation of the butterfly valve members 36 in the diverter valve 28. For example, when the butterfly valve member 36 in the first output pipe 26 is in its open position O_P, exhaust gases from the engine 14 are passed via input pipe 82 into chamber 84. Similarly, when the butterfly valve member 36 in the second output pipe 32 is in its open position Op,, exhaust gases from the engine 14 are passed to the exhaust outlet pipe 88.

The arrangement of the chamber 84 forms a "dwell chamber" which allows the exhaust gases to be held in the vicinity of the methane sensor 86 when the butterfly valve member 36 in the first output pipe 26 is in its open position 0_P, before the exhaust gases are released from the chamber 84. This allows the sensor 86 to sample more effectively.

The provision of the diverter valve 28 in the exhaust system 80 shown in Figure 3 enables the efficiency and effectiveness of the catalyst treatment system 320 to be tested by directing the exhaust gases into chamber 84, when required.

The methane sensor 86 preferably includes a transmitter which allows the methane sensor 88 to transmit measurements to a central control unit 62.

The control unit 62 may then pass this information on to a remote control computer 64.

As with the embodiment described with reference to Figure 2, the control unit 62 may receive information from the diesel and gas control units 66,68 which in turn it may pass on to the remote control computer 64.

The control unit 62 preferably includes a transmitter to control the diverter valve 28, thereby permitting remote control and monitoring of the environment within the exhaust system.

In each of the embodiments described with reference to Figures 1-3, the diverter valve 28 may be controlled, either electrically or remotely, to control the flow of exhaust gases through the pipe system 12 in the event that one of the exhaust routes A,B becomes blocked or malfunctional.

In each of the embodiments described with reference to Figures 1-3, the diverter valve 28 may also include a failsafe arrangement which is operable to control the flow of exhaust gases through the pipe system 12 in the event of a power failure in the diverter valve 28. In such an arrangement, the butterfly valve members 36 may be movable to ensure that the exhaust gases pass along a predetermined one of the exhaust routes A,B by way of default. Alternatively, or in addition, the butterfly valve members 36 may be movable to ensure that in the event that one of the exhaust routes A,B is blocked, for example, in a power failure situation, the exhaust gases pass along the other of the exhaust routes A,B.

Figures 4a-4d show a particular arrangement for diverter valve, as described with reference to Figures 1-3. It will be appreciated that other forms of valve can also be used.

The exhaust system of the invention provides an exhaust system in which different flow rates can be controlled, thus enabling comparative measurements to be obtained for different systems and for the efficiency of exhaust systems to be monitored without adversely affecting the flow of exhaust gases through the system.

Referring now to Figures 5 to 6b, a diverter valve suitable for use in an exhaust system according to the present invention is shown in more detail.

The diverter valve 28 comprises a butterfly valve of the type described hereinabove with reference to Figures 1 to 3 and Figures 4a to 4d. The two butterfly members 36 forming the diverter valve 28 each comprise blades

50 formed on both the input face 21, and the output face 23 of each butterfly valve member 36. One of the butterfly members 36 controls the flow of exhaust gases in a first exhaust route A, and the second butterfly member controls the flow of exhaust gases in a second exhaust route B. The blades

50 cause disruption in the flow of exhaust gases in each of the exhaust routes A, B. In exhaust route A, this results in a substantially complete mixing of exhaust gases which allows a fully representative sample to be collected and tested by a gas sensor 86. In exhaust route B, the disruption to flow caused by the blades 50 in the diverter valve member 36 results in a more even distribution of gases across the face 58 of catalyst 60 forming part of the catalyst system 54.

The walls 62 of the diverter valve 28 in exhaust route A are convex. This produces a venturi effect which enhances swirl caused by the diverter valve 28, further increasing the evenness of distribution across the face 58 of catalyst 60.

Although the illustrated embodiments include a regenerating trap, it is to be understood that in other embodiments of the invention there may be no regenerating trap present.

Claims

1. An exhaust system for an engine system, the exhaust system comprising a pipe system having at least one input port for receiving exhaust gases from the engine system and at least one output port for venting exhaust gases from the exhaust system wherein the pipe system includes at least two exhaust routes for flow of gases from the one or more input ports to the one or more output ports, and further includes a diverter valve operable in response to a control input to control the flow of exhaust gases through the pipe system through one or more of the exhaust routes, the diverter valve comprising at least two butterfly valve members, each butterfly valve member controlling the flow of exhaust gases via one of said exhaust routes, each member having an input face and an output face, at least one input face comprising input disrupting means for disrupting the flow of exhaust gases emitted from the engine system.

2. An exhaust system according to Claim 1 wherein each input face comprises input disrupting means.

3. An exhaust system according to Claim 1 or Claim 2 wherein the input disrupting means comprises one or more blades.

4. An exhaust system according to any one of the preceding claims wherein the diverter valve comprises walls associated with each butterfly member, the walls associated with at least one of the butterfly members being convex.

5. An exhaust system according to any one of the preceding claims wherein at least one output face comprises output disrupting means.

6. An exhaust system according to Claim 5 wherein each output face comprises output disrupting means.

7. An exhaust system according to Claim 5 or Claim 6 wherein the output disrupting means comprises one or more blades.

8. An exhaust system according to any one of the preceding claims wherein at least one of said exhaust routes includes a catalyst treatment system.

9. An exhaust system according to Claim 8 wherein the or each said one of said exhaust routes includes an exhaust gas sensor positioned downstream from the catalyst treatment system.

10. An exhaust system according to Claim 8 or Claim 9 wherein at least one other of said exhaust routes is defined by a bypass pipe.

11. An exhaust system according to Claim 10 wherein the or each bypass pipe includes an exhaust gas sensor.

12. An exhaust system according to any one of Claims 4 to 11 wherein at least one other of said exhaust routes includes a catalyst treatment system.

13. An exhaust system according to Claim 12 wherein the or each said one other of said exhaust routes includes an exhaust gas sensor positioned downstream from the catalyst treatment system.

14. An exhaust system according to any of Claims 8 to 13 further including an exhaust outlet pipe via which exhaust gases exit the exhaust system, said exhaust outlet pipe including an exhaust gas sensor.

15. An exhaust system according to Claim 14 wherein the exhaust outlet pipe includes a continuously regenerating trap.

16. An exhaust system according to any one of Claims 9, 11, 13 and 14 wherein the or each exhaust gas sensor is a methane sensor.

17. An exhaust system according to Claim 1 wherein at least one of said exhaust routes includes a chamber assembly having an open valve and a methane sensor, and the other of said exhaust routes is defined by an exhaust pipe.

18. An exhaust system according to Claim 17 wherein exhaust gases are directed to the diverter valve via a catalyst treatment system, and the diverter valve controls flow to either the chamber assembly or the exhaust pipe.

19. An exhaust system according to any one of Claims 9, 11, 13, 14 and 17 wherein the or each exhaust gas sensor includes a transmitter to transmit data collected by the or each sensor to a data acquisition and control unit.

20. An exhaust system according to any one of the preceding claims wherein the diverter valve includes at least one pair of butterfly valve members mounted on a common spindle at 90° to each other such that when one butterfly valve member is open the other is closed, and vice versa, the diverter valve further including a solenoid to operate the butterfly valve members.

21. An exhaust system according to Claim 20 wherein the solenoid is operable by means of a switch.

22. An exhaust system according to Claim 20 wherein the switch includes a receiver permitting operation of the switch from a remote location.

23. An exhaust system according to Claim 19 and Claim 21 or Claim 22 wherein the data acquisition and control unit controls operation of the solenoid in response to measurements received from the or each exhaust gas sensor.

24. An exhaust system according to any one of Claims 20-23 when dependent from Claim 8 wherein the diverter valve includes a failsafe arrangement which is operable to direct exhaust gases through a catalyst treatment system in the event of a power failure in the diverter valve.

25. An exhaust system according to Claim 24 wherein the failsafe arrangement includes a return spring.

26. An engine system including an engine and an exhaust system according to any one of Claims 1-25.

27. An engine system according to Claim 26 wherein the engine is a dual fuel engine.

28. A diverter valve comprising at least two butterfly valve members, each member having a first face, and an opposite face, at least one of the first faces comprising disrupting means for disrupting the flow of fluids passing through the valve.

29. A diverter valve forming part of an exhaust system according to any one of Claims 1 to 25.

30. An exhaust system generally as herein described with reference to and/or as illustrated in the accompanying drawings.

31. An engine system generally as herein described with reference to and/or as illustrated in the accompanying drawings.

32. A diverter valve generally as herein described with reference to and/or as illustrated in the accompanying drawings.