US20160061090A1

US20160061090A1 - Emissions Cleaning Module

Info

Publication number: US20160061090A1
Application number: US14/783,352
Authority: US
Inventors: Samidha Anand; David Andrews; Simon Cotton; Richard Thomas Clark
Original assignee: Perkins Engines Co Ltd
Current assignee: Perkins Engines Co Ltd
Priority date: 2013-04-11
Filing date: 2014-04-11
Publication date: 2016-03-03
Also published as: EP2984312B1; EP2984312A2; CN105392972B; CN105392972A; GB201306613D0; WO2014167351A2; WO2014167351A3

Abstract

An emissions cleaning module includes a first and second conduit. The first conduit contains a diesel oxidation catalyst (DOC) module and a diesel particulate filter (DPF) module; the second conduit contains a selective catalytic reduction (SCR) module. The emissions cleaning module is mounted to an external support by means of a mounting mechanism including at least one adjustable strap which is clamped around a conduit; and at least one saddle which is mounted to the conduit by the at least one adjustable strap. The saddle includes a curved upper surface configured to conform substantially to a portion of the conduit.

Description

TECHNICAL FIELD

This disclosure relates to an apparatus for cleaning exhaust gases emitted during the operation of an engine such as an internal combustion engine and a mounting mechanism therefore.

BACKGROUND

Engines, for example internal combustion (IC) engines burning gasoline, diesel or biofuel, output various substances as part of their exhaust gases which must be treated to meet current and future emissions legislation. Most commonly those substances comprise hydrocarbons (HC), carbon monoxides (CO), mono-nitrogen oxides (NO_x) and particulate matter, such as carbon (C), a constituent of soot. Some of those substances may be reduced by careful control of the operating conditions of the engine, but usually it is necessary to provide an emissions cleaning module downstream of the engine to treat at least some of those substances entrained in the exhaust gas. Various apparatus for reducing and/or eliminating constituents in emissions are known. For example, it is known to provide an oxidation device, such as a diesel oxidation catalyst (DOC) module, to reduce or to eliminate hydrocarbons (HC) and/or carbon monoxide (CO). Oxidation devices generally include a catalyst to convert those substances into carbon dioxide and water.
As a further example, emissions cleaning modules may include filtration devices, such as a diesel particulate filter (DPF) module, to restrict the particulates present in the exhaust gas from being output to atmosphere. The soot collected in the filtration device must be removed subsequently to maintain the efficiency of the filtration device. The methods by which soot may be removed from the filtration device are well known in the art and may generally be referred to as regeneration, which generally occurs at elevated temperatures.
In addition, it is known to reduce or eliminate mono-nitrogen oxides (NO_x) in diesel combustion emissions by conversion to diatomic nitrogen (N₂) and water (H₂O) by catalytic reaction with reductant chemicals such as ammonia (NH₃) entrained in the exhaust gas. Generally ammonia is not present in exhaust gas and must therefore be introduced upstream of a catalyst, typically by injecting a urea solution into the exhaust gas which decomposes into ammonia at sufficiently high temperatures.
By these methods, engine emissions can be cleaned, meaning that a proportion of the substances which would otherwise be released to atmosphere are instead converted to carbon dioxide (CO₂), nitrogen (N₂) and water (H₂O).
Against this background there is provided an emissions cleaning module and a mounting mechanism therefore.

SUMMARY OF THE DISCLOSURE

The disclosure therefore provides an emissions cleaning module comprising:

- a conduit; and
- a mounting mechanism for mounting the emissions cleaning module to an external support;
- said mounting mechanism comprising:
- at least one adjustable strap which is clamped around the conduit; and
- at least one saddle which is mounted to the conduit by the at least one adjustable strap;
- wherein the at least one saddle comprises an upper surface which is shaped so as to conform substantially to a portion of the conduit The disclosure also provides an emissions cleaning module comprising:
- a first conduit containing a diesel oxidation catalyst (DOC) module and a diesel particulate filter (DPF) module;
- a second conduit containing a selective catalytic reduction (SCR) module; and
- a mounting mechanism for mounting the emissions cleaning module to an external support;
- said mounting mechanism comprising:
- at least one adjustable strap which is clamped around each conduit; and
- at least one saddle which is mounted to each conduit by the at least one adjustable strap;
- wherein the first and second conduits are mounted adjacent one another on the mounting mechanism and the at least one saddle comprises an upper surface which is shaped so as to conform substantially to a portion of the conduit.

The disclosure further provides mounting mechanism for an emissions cleaning module comprising:

- at least a pair of adjustable straps;
- at least a pair of saddles; and
- a mounting plate;
- wherein each of the saddles comprise an upper surface which is shaped so as to conform substantially to a portion of the conduit and the saddles are mounted adjacent each other on the mounting plate.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 shows a perspective view of an emissions cleaning module;

FIG. 2 shows an end elevation the emissions cleaning module of FIG. 1;

FIG. 3 shows a plan view of the top of the emissions cleaning module of FIG. 1;

FIG. 4 shows a partly exploded perspective view of the emissions cleaning module of FIG. 1 from a further angle showing the flowhood removed from the end of the first and third conduits;

FIG. 5 shows the partly exploded perspective view of the emissions cleaning module of FIG. 4 from another angle;

FIG. 6 shows a plan view of the underside of the emissions cleaning module of FIG. 1; and

FIG. 7 shows a perspective view of part of a mounting mechanism of the emissions cleaning module of FIG. 1.

DETAILED DESCRIPTION

In the following description an embodiment of an emissions cleaning module 1 will be described and components of said emissions cleaning module 1 will be discussed. It is to be understood that, unless explicitly stated, the described features and components may be present in different combinations to provide other embodiments.
The emissions cleaning module 1 may comprise a plurality of exhaust gas treatment devices. In the following description reference will be made to the emissions cleaning module 1 comprising one or more of a diesel oxidation catalyst (DOC) module, a diesel particulate filter (DPF) module, a selective catalytic reduction (SCR) module and an AMOX module. It will be appreciated that the emissions cleaning module 1 may also contain any other exhaust gas treatment devices as known in the art.
A DOC module may comprise one or more catalysts, such as palladium or platinum, which may be in the form of catalyst bricks. These materials serve as catalysts to cause the oxidation of hydrocarbons ([HC]) and carbon monoxide (CO) present in the exhaust gas in order to produce carbon dioxide (CO₂) and water (H₂O) and the oxidization of nitrogen monoxide (NO) into nitrogen dioxide (NO₂). The catalysts may be distributed in a manner so as to maximise the surface area of catalyst material in order to increase effectiveness of the catalyst in catalysing reactions. The catalyst bricks are inherently variable in diameter, up to +/−2.5 mm.
A DPF module may comprise a DPF which collects particulate matter, such as carbon in the form of soot, from the exhaust gas. The DPF may also include a catalyst or precious metal and washcoat to help the DOC with the oxidization of nitrogen monoxide (NO) into nitrogen dioxide (NO₂). The catalyst of the DPF may be coated on a substrate with a honeycomb or other elongated channel or thin wall structure. The DPF substrate may be more porous than the DOC substrate and every other channel may be blocked with half the channels blocked at the inlet end and half blocked at the outlet end. This increased porosity and the blocked channels encourage wall flow of the exhaust gas. The wall flow causes the soot to be filtered and collected in the DPF.
Like the DOC, different types of DPFs may be configured for different types of after treatment systems with different DPF regeneration strategies.
An SCR module may comprise one or more catalysts through which a mixture of exhaust gas and urea/ammonia may flow. As the mixture passes over the surfaces of the catalyst a reaction may occur which converts the ammonia and NOX to diatomic nitrogen (N₂) and water (H₂O).
An AMOX module may comprise an oxidation catalyst which may cause residual ammonia present in the exhaust gas to react to produce nitrogen (N₂) and water (H₂O).
The emissions cleaning module 1 comprises a first conduit 2, a second conduit 4, and a third conduit 3. The first conduit 2 may be elongate and have a longitudinal axis 20 defining its axis of elongation. The second conduit 4 may be elongate and have a longitudinal axis 30 defining its axis of elongation. The third conduit 3 may be elongate and have a longitudinal axis 40 defining its axis of elongation. The first conduit 2, second conduit 4 and third conduit 3 may be arranged parallel to one another such that the longitudinal axes 20, 40, 30 are parallel to one another. The emissions cleaning module 1 may have a first end 18 and a second end 19.
The first conduit 2 may comprise a cylindrical body 21. An inlet connector 26 may be mounted to an inlet end 22 of the cylindrical body 21 nearest the first end 18 of the emissions cleaning module 1. The inlet connector 26 may comprise a flared section 28 that is mounted to the cylindrical body 21 and which may taper to join with a mounting pipe 27 which may define an inlet 25 of the first conduit 2. In use, a conduit carrying exhaust gas may be connected to the mounting pipe 27. An end of the cylindrical body 21 nearest the second end 19 of the emissions cleaning module 1 may define an outlet 205 of the first conduit 2 (see FIG. 4).
The cylindrical body 21 may comprise ridges 24, which may lie proud of a remainder of the cylindrical body 21 and which may be spaced along the longitudinal axis 20. One ridge 24 may be located nearest the first end 18. Another ridge 24 may be located nearest the second end 19. A further ridge 24 may be located in between the other two ridges 24.
The first conduit 2 may house a diesel oxidation catalyst (DOC) module (not shown). The DOC module may comprise one or more DOC elements which may be configured differently. For example a different catalytic treatment may be applied to each element. The DOC module may be located in a first portion of the first conduit 2 towards the inlet 25.
The first conduit 2 may also house a diesel particulate filter (DPF) module (not shown). The DPF module may be located in a second portion of the first conduit 2 towards the outlet 205 of the first conduit 2.
The outlet 205 of the first conduit 2 may be fluidly connected to an inlet end of the third conduit 3 by a flowhood 5. The flowhood 5 (see FIGS. 4 and 5) may comprise a rear wall 55 with a sidewall 56 extending therefrom. A flowhood flange 57 may extend outwardly from the free edge of the sidewall 56. A plate 58 defining a lower aperture and an upper aperture, may be provided to support, respectively, an outlet end of the first conduit 2 and an inlet end of the third conduit 3. The aforesaid ends of the first and third conduits 2,3 may be welded, or otherwise attached, in said lower and upper apertures. The flowhood flange 57 may be welded, or otherwise attached, to the plate 58. The flowhood 5 may be generally tapered so that it is wider at a lower end, which is located over the outlet end of the first conduit 2, and narrower at an upper end, which is located over the inlet end of the third conduit 3.
A flowhood cover 7 may be provided to reduce the transmission of thermal emissions to the surroundings of the emissions cleaning module 1. The flowhood cover 7 may also act to help maintain an elevated temperature within portions of the emissions cleaning module 1. The flowhood cover 7 may be designed to substantially fully envelop all external surfaces of the flowhood 5. In addition, the flowhood cover 7 may be configured to envelop at least a portion of the cylindrical body 31 of the third conduit 3. In addition, the heat shield may be configured to envelop at least a portion of the cylindrical body 21 of the first conduit 2 near where it is connects to the flowhood 7.
The flowhood cover 7 may therefore comprise a first section 70 and a second section 71 which may be joined together, for example by welding. The second section 71 may have a first aperture 72 which may be surrounded by a first flange 73. The first flange 73 may located around the outlet end of the first conduit 2. The second section 71 may have a second aperture 74, from which a cylindrical tube 77 projects. When assembled, the cylindrical tube extends through the over the third conduit 31.
The emissions cleaning module 1 may comprise one or more sensors for determining one or more conditions in the emissions cleaning module 1, such as temperature, soot level in the DPF or quantity of NO_x. Each sensor may at least partially penetrate a conduit 2, 3, 4 or the flowhood 7 of the emissions cleaning module 1, such that those elements of the sensor (i.e. electronic components) which need not be located within a volume to be sensed may be located on an exterior surface of the emissions cleaning module 1. In this manner, sensitive elements of the sensors can be located away from high temperatures likely to occur inside the conduit. The sensors may be arranged such that those elements of the sensors located on the exterior surface of the emissions cleaning module 1 may be located in a manner which allows for increased air flow. This may help to reduce damage to the sensors which might otherwise be caused due to heat.
Two temperature sensors 29 may be mounted in the first conduit 2 to measure the temperature of the exhaust gas within the first conduit 2. The temperature sensors 29 may extend into an interior of the first conduit 2 such that a distal end of the temperature sensor 29 may lie on or in proximity to the longitudinal axis 20 of the first conduit 2. The temperature sensors 29 may be mounted so as to measure the temperature of the exhaust gas on entry into the DOC module and on exit from the DOC module, prior to its passage through the DPF module. A first temperature sensor 29 is therefore mounted in the inlet end 22 of the first conduit 2 close to the inlet connector 26. A second temperature sensor 29 may be mounted part way along the first conduit 2 as shown in FIG. 1. The temperature sensors 29 may be connected to an external engine control module (not shown), by means of suitable temperature sensor leads.
A soot sensor 50,51 may be provided to determine the soot loading in the DPF of the DPF module. The soot sensor 50,51 may be an RF sensor which utilises radio frequency technology to determine the accumulated soot in the DPF and transmit the measurements to the control module. The soot sensor 50, 51 may comprise a transmitter 51 and a receiver 50 mounted in the first conduit 2 on either side of the DPF and configured to transmit and receive, respectively, radio frequency signals through the DPF. Each of the transmitter 51 and receiver 50 may include an antenna capable of either transmitting or receiving RF signals passed through the DPF. An RF soot sensor monitor (not shown) may be configured to receive signals from the transmitter 51 and receiver 50 and output signals to the engine control module which are indicative of an attenuation of RF signals transmitted through the DPF, which may be indicative of a relative soot loading state of the DPF. One of the receiver 50 or transmitter 51 may be mounted in a boss 53, which is itself mounted in the sidewall 56 of the flowhood 5 between the first and third conduits 2, 3. The boss 53 on the receiver 50 or transmitter 51 thus mounted may extend through an aperture 75 in the first section 70 of the flowhood cover 7.
A NO sensor may also be provided to measure the quantity of NO in the exhaust gas after it has passed through the DOC and DPF modules in the first conduit 2 and before it enters the SCR module in the second conduit 4. The NO sensor may therefore be mounted in the flowhood 7 between the first and third conduits 2, 3. The NO sensor may be mounted in a boss 52. A choice of two locations for the boss 52 is shown in the Figures, on the side or rear wall 56,55 of the flowhood 5. The use of a boss 52 allows the tip of the NO sensor to be located in a region of higher flow of the exhaust gas. If the NO sensor tip is located in a larger volume, i.e. further within the volume of the flowhood 5, the velocity of flow across the NO sensor tip may not be sufficient to provide an accurate measurement. The boss 52, and therefore the NO sensor, extends through an aperture 76 in the first section 70 of the flowhood cover 7.
The third conduit 3 may house a mixer module. The mixer module may be configured to mix a reductant fluid, such as ammonia or urea, injected by an injector module 9 with the exhaust gas passing from the first conduit 2. The third conduit 3 may comprise a cylindrical body 31 defining a mixing chamber in which a mixing element 33 may be located. The injector module 9 may be mounted in an aperture in the rear wall 55 in the flowhood 5 so as to extend into the mixer module. The injector module 9 may extend through an aperture in the flowhood cover 7. One or more injector lines may interconnect the injector module 9 with a supply of injector fluid.
A flow connector 10 may be provided to fluidly connect an outlet end 310 of the third conduit 3 with an inlet end of the second conduit 4. As shown in FIG. 1, the flow connector 10 may have an elbow-shaped configuration wherein a first end 121 of the flow connector 10 is aligned with the cylindrical body 31. A second end 122 of the flow connector 10 is oriented at approximately 90° to the first end 121 so as to connect to the second conduit 4 in a direction perpendicular to the longitudinal axis 40 of the second conduit 4. The flow connector 10 may have a double skin construction comprising an outer wall and an inner wall. A gap between the outer wall and inner wall may be provided as a void space or may alternatively be filled with an insulating material.
The cylindrical body 31 of the third conduit 3 may be connected to the first end 121 of the flow connector 10 by means of a ring 13 and clamp 14. An end of the cylindrical body 31 defining an outlet end 310 of the third conduit 3 may be received in a first end of the ring 13 and a second end of the ring 13 may be mounted on the first end 121 of the flow connector 10. A clamp 14 may be provided to clamp the ring 13 to the cylindrical body 31 of the third conduit 3. The clamp 14 may be of a type whose diameter may be adjusted by a suitable mechanism. An example of a suitable clamp is a Teconnex™ clamp. Additional fastening means, such as welding, may be provided between the ring 13 and the cylindrical body 31 if desired. The ring 13 may be fastened to the flow connector 10 by means of a suitable fastening mechanism such as, for example, welding.
The second conduit 4 may comprise a cylindrical body 41. A first end section 45 may be sealingly connected to the cylindrical body 41 at an end of the cylindrical body 41 nearest the first end 18 of the emissions cleaning module 1. A second end section 46 may be sealingly connected to the cylindrical body 41 at an end of the cylindrical body 41 nearest the second end 19 of the emissions cleaning module 1.
The first end section 45 may define a closed first end of the second conduit 4. The flow connector 10 may be fluidly connected to the first end section 45. The second end section 46 may be provided with an outlet connector 48 defining an outlet of the second conduit 4. The outlet connector 48 may comprise a conical section 403 that may be mounted to the second end section 46 and which may taper to join with a cylindrical mounting pipe 402 which is connected to the second conduit 4. In use, a section of external pipe work forming a portion of an exhaust arrangement may be connected to the cylindrical mounting pipe 402.
The cylindrical body 41 may comprise ridges 42 which may lie proud of a remainder of the cylindrical body 41 and which may be spaced along the longitudinal axis 40. One ridge 42 may be located nearest the first end 18. Another ridge 42 may be located nearest the second end 19. A further ridge 42 may be located in between the other ridges 42.
The second conduit 4 may contain an SCR module. The SCR module may be located within the cylindrical body 41 towards the first end 18 of the emissions cleaning module 1. The second conduit 4 may also contain an AMOX module. The AMOX module may be located within the cylindrical body 41 towards the second end 19 of the emissions cleaning module 1 so as to be downstream of the SCR module.
A temperature sensor 49 may be mounted in the second conduit 4. The temperature sensor 49 may be mounted in the first end section 45. The temperature sensor 49 may be located immediately upstream of the SCR module. The temperature sensor 49 may extend into an interior of the second conduit 4. The temperature sensor 49 may be connected to the engine control module by means of a suitable temperature sensor lead.
A mounting mechanism 6 may be provided for mounting the emissions cleaning module 1 to an external support or mount, for example a chassis. The mounting mechanism 6 provides a means for mounting one or both of the first conduit 2 and the second conduit 4 to the external support or mount. The mounting mechanism comprises one or more mounting saddles 63. As shown in FIG. 7, the mounting mechanism 6 may comprise a mounting plate 60 having at least one pair of mounting saddles 63 fastened thereto. The arrangement of the mounting saddles 63 on the mounting plate 60 may be such that the first conduit 2 and the second conduit 4 are mounted adjacent to each other. The arrangement may also be such that the first conduit 2 and the second conduit 4 are mounted parallel to each other.
The mounting saddle 63 may be designed to distort in order to conform to the cylindrical body 41 of the conduit 2, 4 mounted thereon. This may reduce stress in the mounting mechanism 6 and improve retainment (i.e. increase natural frequency) of the first and/or second conduits 2, 4 on the mounting plate 60. The mounting saddle 63 may have an upper surface 601 for supporting the conduit 2,4. The upper surface 601 is flexible so as to conform substantially to a portion of the conduit 2,4 located thereon.
The mounting saddle 63 may comprise a lower element 64 and an upper element 69. The lower element 64 may comprise upwardly extending flanges 66 on each side. Bolt holes 67 may be provided for fastening the lower elements 64 to the mounting plate 60 by means of bolts.
The flanges 66 of the lower element 64 may each have an enlarged lobe section at each end in each of which may be formed a hole. Thus each lower element 64 may have two pairs of holes.
The upper element 69 of each mounting saddle 63 may comprise said curved upper surface 601 which is configured to conform substantially to a portion of the cylindrical body 41 of the first and second conduits 2, 4, which may or may not be the same The upper surface 601 may be shaped to conform substantially to a portion of the cylindrical body 41 of the first and second conduits 2, 4. The upper element 69 may be provided with a pair of flanges 602 at each end which extend downwardly and may have formed therein holes. As shown in FIG. 7, the upper elements 69 may thus be mounted to the lower element 64 by means of fastening means 604, such as bolts, which may pass through the pairs of holes and in the lower element 64 and upper element 69 respectively. The mounting saddle may be provided with cylindrical spacers 614 overlying the fastening means 604 which may extend between the flanges 66. The cylindrical spacers 614 may act to strengthen the lower elements 64 and help restrict distortion when the fastening means 604 are tightened. The holes may be circular or slotted.
The mounting mechanism 6 may further comprise an adjustable strap 606 associated with each mounting saddle 63. The mounting mechanism 6 may comprise two pairs of adjustable straps 606. A first pair of adjustable straps 606 may extend around the cylindrical body 41 of the first conduit 2 and pass through a first pair of mounting saddles 63 between the lower element 64 and the upper element 69. The second pair of adjustable straps 606 may extend around the cylindrical body 41 of the second conduit 4 and pass through the second pair of mounting saddles 63 between the lower element 64 and the upper element 69. Each adjustable strap 606 may comprise an elongate member 607 which may be formed from a metal band. The adjustable straps 606 may be located between pairs of ridges 42 on the cylindrical body 41 or pairs of ridges 24 on cylindrical body 21.
At each end of the elongate member 607, a pair of end loops 608 may be formed which may receive co-operating portions of an adjustable clamp 609. Each adjustable clamp 609 may comprise a first fixing 610 received in a pair of end loops 608 at one end of the elongate member 607 and a second fixing 611 received in the pair of end loops 608 at the other end of the elongate member 607. A threaded connector 612 may be provided which may be mounted to the first fixing 610 and extend through an aperture in the second fixing 611. A nut adjuster 613 may be received on the threaded connector 612 and by movement of the nut adjuster 613 along the threaded connector 612, the distance between the co-operating portions may be adjusted and hence the circumference of the adjustable strap 606 may be adjusted.
As the adjustable strap 606 is tightened around the cylindrical body 41 or the conduit 2,3, the upper surface 601 flexes to conform to the portion of the conduit 2,4 located thereon. The fastening means may then be tightened to hold the upper surface 601 rigid. This configuration may enable one or more conduits 2,4 having different curvatures to be securely supported.
The mounting plate 60 may be provided with bolt holes 61 for receiving fastening means such as bolts for mounting the mounting plate 60 to the external support.

INDUSTRIAL APPLICABILITY

In use, the emissions cleaning module 1 may be mounted to a chassis, or similar external support, by use of the mounting mechanism 6. A conduit originating from a source of exhaust gas, for example a diesel combustion engine, may be connected to the mounting pipe 27. A section of external pipe work forming a portion of an exhaust arrangement may be connected to the mounting pipe 402 of the second conduit 4.
During operation exhaust gas may be supplied to the emissions cleaning module 1 via the inlet 25. The temperature of the incoming exhaust gas may be sensed as it passes through the inlet connector 26 by the temperature sensor 29 and the information transmitted to an external processing unit.
The exhaust gas may then pass into the DOC module in the first conduit 2. Prior to receipt at the inlet 25, the pressure of the exhaust gas may be controlled by a back pressure valve. The DOC module may function to cause oxidation of hydrocarbons ([HC]) and carbon monoxide (CO) present in the exhaust gas to produce carbon dioxide (CO₂) and water (H₂O).
The exhaust gas may then pass into the DPF module in the first conduit 2. In the DPF module, carbon particles (C) in the form of soot in the exhaust gas are trapped in the DPF as the exhaust gas passes there through. The soot sensor 50,51 monitors the soot levels in the DPF, such that the engine control module may command operation of a regeneration process responsive to a soot loading state of the DPF. The location of one of the components of the soot sensor 50,51 in the flowhood 5 may enable the length of the first conduit 2 to be shorter than if it were located in the first conduit 2 itself. This may enable the overall length of the emissions cleaning module 1 to be reduced in length.
The temperature within the DPF module may affect the extent to which RF energy is attenuated when transmitted through the DPF containing trapped soot. In general, the attenuation is negatively correlated with temperature, and thus the engine control module may be configured to determine a relative soot loading state of the DPF also in response to inputs from the temperature sensors 29.
The temperature of the exhaust gas in the DPF module may also be used to trigger a DPF regeneration process.
The exhaust gas may then pass through the outlet 205 of the first conduit 2 into the flowhood 5. The exhaust gas may then be channeled by the flowhood 5 around towards the inlet of the third conduit 3.
A reductant fluid, such as urea or ammonia, may be injected by the injector module 9 into mixing element and thus into the flow of exhaust gas. The patterns of fluid flow which may be induced in the exhaust gas by the mixing element 33 may promote mixing of the injected fluid with the exhaust gas. Such mixing may promote heat transfer from the relatively hot exhaust gas to the injected fluid which may promote conversion of the urea, where used, to ammonia. Such mixing may also produce a more uniform mixture of the injected fluid within the exhaust gas.
As the exhaust gas passes through the flowhood 5, the NO_xlevel in the exhaust gas is monitored by the NO_xsensor. The measurement of NO_xmay be used to determine the level of reductant fluid injected by the injector module 9. For example, during engine idle conditions, the injection of reductant fluid may be reduced for at least partially suspended because lower amounts of reductant fluid are needed when low levels of NO_xare produced by the engine. During non-idle engine conditions, higher levels of NO_xare produced, so a greater level of reductant fluid is required.
The mixture of the exhaust gas and the injected reductant fluid may then pass along the third conduit 3 via a swirl unit, where present. The swirl unit may induce a swirling motion into the flow of fluid, which may promote greater uniformity in concentration of the injected fluid within the exhaust gas. The swirl unit is an optional component.
Fluid may then pass via the flow connector 10 into the second conduit 4 and through the SCR module contained therein. The temperature of the fluid entering the second conduit 4 may be sensed by the temperature sensor 49 and the information transmitted to the control module. The operation of the SCR module is sensitive to temperature. The measurement of the temperature of the fluid may therefore be used by the engine control module to thermally manage the operation of the SCR module.
As the fluid passes over the surfaces of the catalyst within the SCR module a reaction may occur which converts the ammonia and NO to diatomic nitrogen (N₂) and water (H₂O).
Fluid may then pass from the SCR module to the AMOX module, where present, located further downstream in the second conduit 4. The AMOX module may function to cause any residual ammonia present in the exhaust gas to react to produce nitrogen (N₂) and water (H₂O).
From the AMOX module the fluid may pass out of the outlet via the outlet connector 48 and into the external pipework.

Claims

The invention claimed is:

1. An emissions cleaning module comprising:

a conduit; and

a mounting mechanism for mounting the emissions cleaning module to an external support;

said mounting mechanism comprising:

at least one adjustable strap which is clamped around the conduit; and

at least one saddle which is mounted to the conduit by the at least one adjustable strap;

wherein the at least one saddle comprises a curved upper surface configured to conform substantially to a portion of the conduit.

2. An emissions cleaning module comprising:

a first conduit containing a diesel oxidation catalyst (DOC) module and a diesel particulate filter (DPF) module;

a second conduit containing a selective catalytic reduction (SCR) module; and

said mounting mechanism comprising:

at least one adjustable strap which is clamped around each conduit; and

at least one saddle which is mounted to each conduit by the at least one adjustable strap;

wherein the first and second conduits are mounted adjacent one another on the mounting mechanism and the at least one saddle comprises a curved upper surface configured to conform substantially to a portion of the conduit.

3. An emissions cleaning module as claimed in claim 1, wherein the upper surface is flexible.

4. An emissions cleaning module as claimed in claim 1 wherein the at least one saddle comprises an upper element and a lower element, the upper element and the lower element being connectable together; the upper element being retained to the conduit respectively by means of one of the at least one adjustable strap.

5. An emissions cleaning module as claimed in claim 4, wherein the upper element and the lower element are connected together by at least one fastening means.

6. An emissions cleaning module as claimed in claim 1 further comprising a mounting plate to which the at least one saddle is mounted, the lower element being retained to the mounting plate.

7. An emissions cleaning module as claimed in claim 1 further comprising a first conduit containing a diesel oxidation catalyst (DOC) module and a diesel particulate filter (DPF) module and a second conduit containing a selective catalytic reduction (SCR) module.

8. An emissions cleaning module as claimed in claim 7 wherein the first and second conduits are mounted adjacent one another on the mounting plate.

9. An emissions cleaning module as claimed in claim 8 wherein the first and second conduits are mounted parallel to one another on the mounting plate.

10. An emissions cleaning module as claimed in claim 7 wherein the mounting mechanism comprises at least one adjustable strap clamped around each of the first and second conduits and at least one saddle which is mounted to each of the first and second conduits by the adjustable straps.

11. An emissions cleaning module as claimed in claim 2, further comprising a third conduit containing a mixing element and a flowhood having an inlet fluidly connected to an outlet of the first conduit and an outlet fluidly connected to an inlet of the second conduit.

12. An emissions cleaning module as claimed in claim 11 further comprising a soot sensor configured to determine an amount of soot in a DPF of the DPF module, said soot sensor being an RF sensor having a transmitter and a receiver located at opposing ends of the DPF.

13. An emissions cleaning module as claimed in claim 12 wherein one of the transmitter and receiver is mounted in the first conduit at an inlet end of the DPF module and the other of the transmitter and receiver is mounted in the flowhood.

14. An emissions cleaning module as claimed in claim 11 further comprising a NOx sensor located to determine a quantity of NOx in exhaust gas flowing through the emissions cleaning module before it passes into the SCR module.

15. An emissions cleaning module as claimed in claim 14 wherein said NOx sensor is mounted in the flowhood.

16. An emissions cleaning module as claimed in claim 14 in which the NOx sensor is mounted in a boss, which is mounted in the flowhood.

17. A mounting mechanism for an emissions cleaning module comprising:

at least a pair of adjustable straps;

at least a pair of saddles; and

a mounting plate;

wherein each of the saddles comprise a curved upper surface configured to conform substantially to a portion of the conduit and the saddles are mounted adjacent each other on the mounting plate.

18. A mounting mechanism for an emissions cleaning module as claimed in claim 17 wherein the upper surfaces are flexible.

19. A mounting mechanism as claimed in claim 17, wherein each of the saddles comprises an upper element and a lower element, the upper element and the lower element being connectable together; the upper elements being mountable to a first conduit and a second conduit of an emissions cleaning module by means of the adjustable straps and the lower elements being mountable to the mounting plate.

20. An emissions cleaning module as claimed in claim 2 wherein the at least one saddle comprises an upper element and a lower element, the upper element and the lower element being connectable together; the upper element being retained to the conduit respectively by means of one of the at least one adjustable strap.