Technical Field

This disclosure is directed to an aftertreatment system support assembly.

Background

Engines, for example internal combustion engines burning gasoline, diesel, or biofuel, output various substances which must be treated to meet current and future emissions legislation. Most commonly, such substances comprise hydrocarbons (HC), carbon monoxides (CO), mono-nitrogen oxides (NOx), 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 aftertreatment module downstream of the engine to treat at least some of the substances entrained in the exhaust gas.

Various apparatus for reducing and/or eliminating constituents in emissions are known. By these methods, engine emissions can be cleaned, meaning that a proportion of the substances which would otherwise be released into the atmosphere are instead converted to carbon dioxide (CO2), nitrogen (N2) and water (H2O).

For example, it is known to provide an oxidation device, such as a diesel oxidation catalyst (DOC), 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, aftertreatment modules may include filtration devices to restrict the particulates present in the exhaust gas from being output to the atmosphere, such as a diesel particulate filter (DPF). The soot collected in the filtration device must later be removed 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 is carried out at elevated temperatures. In addition, it is known to reduce or eliminate mono-nitrogen oxides (NOx) in diesel combustion emissions by selective catalytic reduction (SCR). In a typical SCR system, urea or a urea-based water solution is mixed with exhaust gas. In some applications, a urea solution is injected directly into an exhaust passage through a specialised injector device. The injected urea solution mixes with exhaust gas and breaks down to provide ammonia (NH3) in the exhaust stream. The ammonia then reacts with nitrogen oxides (NOx) in the exhaust at a catalyst to provide nitrogen gas (N2) and water (H2O).

Such aftertreatment systems are typically packaged in one or more metal canisters, which may be mounted directly on the internal combustion engine. Vibration from the engine may excite the aftertreatment system, causing it to radiate noise. As the canister may typically be a light structure of large surface area, overall engine noise levels may be greatly increased, even doubled. Known systems to mitigate this effect employ rubber damper mechanisms to isolate the canister from the engine. However, such systems are generally costly and may add significant complexity to the overall engine package.

Summary

According to the present disclosure, there is provided an aftertreatment system support assembly for mounting an aftertreatment system module on an engine. The aftertreatment system support assembly comprises: an aftertreatment system module; a bracket configured to be mounted on an engine, the bracket further being configured to support the aftertreatment system module; retaining means for securing the aftertreatment system module to the bracket; and a vibration attenuator sandwiched between the bracket and the aftertreatment system module, the vibration attenuator further sandwiched between the retaining means and the aftertreatment system module; wherein the vibration attenuator is in direct contact with each of the aftertreatment system module, the bracket, and the retaining means.

The vibration attenuator, positioned directly between the support and the aftertreatment system module, may act as a disruptor, attenuating vibrations transmitted from the engine to the aftertreatment system module. By reducing the vibrations transmitted from the engine to the aftertreatment system module, the resulting noise radiated is reduced. 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:

Figure 1 is a block diagram of a typical exhaust aftertreatment system; and

Figure 2 is a perspective view of an aftertreatment system support assembly according to the present disclosure; and

Figure 3 is a perspective view of the aftertreatment system support assembly of Figure 2 in respect of two aftertreatment system modules.

Detailed Description

Figure 1 illustrates a block diagram of a typical exhaust aftertreatment system 10 associated with the engine 11 of a machine (not shown). The term ‘machine’ is used generically to describe any machine driven by mechanical means by an engine through a transmission. The machine may be a work machine, such as a backhoe loader. The engine 11 may be an internal combustion engine, such as a diesel engine.

The aftertreatment system 10 may be modularly packaged in one or more aftertreatment system modules 5, as shown in the illustrated embodiment, for retrofit onto existing engines or, alternatively, for installation on new engines. As shown in Figure 1, the aftertreatment system modules 5 may include a first module 12 that may be fluidly connected to an exhaust conduit 13 of the engine 11. The first module 12 may contain various exhaust gas treatment devices such as a diesel oxidation catalyst (DOC) 14 and a diesel particulate filter (DPF) 15, but other devices may be used.

A transfer conduit 20 may fluidly interconnect the first module 12 with a second module 21. The second module 21 may enclose an SCR catalyst 22 and an Ammonia Oxidation Catalyst (AMOX) 23. An exhaust outlet 24 may be fluidly connected to the second module 21 such that the exhaust gas that has passed through the second module 21 may be released into the atmosphere. The SCR catalyst 22 and AMOX 23 may operate to treat exhaust gas from the engine 11 in the presence of ammonia. The ammonia may be provided through degradation of a urea-based water solution 25 (commonly known as diesel exhaust fluid, DEF) injected into the exhaust gas in the transfer conduit 20 by an injector 30. The DEF 25 may meet the ISO22241 standard and comprise from 31.8% to 33.2% urea by weight. A DEF system 29 may be provided, wherein the DEF 25 may be contained within a reservoir 31 and may be provided to the injector 30 by a pump 32, which may be located in a DEF conduit 33 fluidly connecting the reservoir 31 to the injector 30. The pump 32 may pressurise the DEF system 29 to an operating pressure. A typical operating pressure may be 5 bar or 9 bar, but other operating pressures may also be possible, for example less than 5 bar or greater than 9 bar. To promote mixing of DEF 25 with the exhaust gas in the transfer conduit 20, a mixer 34 may be disposed along the transfer conduit 20, downstream of the injector 30.

The components of the aftertreatment system 10 may depend on the relevant emissions regulations of the intended territory for the machine. For example, in some territories both the first and second modules 12,21 may be required, whereas in other territories only the first module 12 may be required.

Figures 2 and 3 illustrate an aftertreatment system support assembly 1 which may be used to mount one or more aftertreatment system modules 5 to an engine 11 (the engine 11 itself not being shown in Figures 2 or 3). The mounting location of the one or more aftertreatment system modules 5 on the engine 11 may be determined by machine packaging requirements. A common aftertreatment system 10 mounting location is on top of the engine 11, with the one or more aftertreatment system modules 5 mounted longitudinally with respect to the engine 11. Another common aftertreatment system 10 mounting location is at the rear of the engine 11, with the one or more aftertreatment system modules 5 mounted transverse to an engine 11 crankshaft axis.

Figure 2 shows a single aftertreatment system support assembly 1, while Figure 3 shows two aftertreatment system support assemblies 1 used to mount first and second modules 12,21. Where first and second modules 12,21 are present, the first module 12 is typically positioned below the second module 21. Figure 3 shows the first and second modules 12,21 mounted in an ‘offset’ arrangement, wherein the first and second modules 12,21 are offset from each other in a vertical direction. Alternatively, the first and second modules 12,21 may be mounted in a ‘stacked’ arrangement (not shown), wherein the first and second modules 12,21 are aligned with each other in a vertical direction.

The aftertreatment system support assembly 1 may generally comprise an aftertreatment system module 5, a support 41 , and a vibration attenuator 43.

As shown in Figures 2 and 3, the aftertreatment system module 5 (such as the first and second modules 12,21) may comprise a canister 40 housing one or more exhaust gas treatment devices (such as a DOC 14, a DPF 15, an SCR catalyst 22, an AMOX 23, or another exhaust gas treatment device). The canister 40 may be generally cylindrical. The canister 40 may comprise a lightweight metal can, which may be made of steel. The canister 40 may be single skinned or double walled. Heat insulation may be provided at an inner surface of the canister 40.

The support 41 may be configured to be mounted on the engine 11, and may further be configured to support the aftertreatment system module 5. In one example, the support 41 may comprise a bracket (which may also be termed a ‘support bracket’, a ‘mounting bracket’ or a ‘support plate’). The aftertreatment system module 5 may sit upon the support 41. In particular, the support 41 may comprise a support surface upon which the aftertreatment system module 5 may sit. The support surface may be curved to receive the aftertreatment system module 5, or the support surface may be flat. The support 41 may be a fabricated design, or it may be cast. The support 41 may be made of a metal. For example, the support 41 may be made of cast iron. Where two aftertreatment system support assemblies 1 are used to mount first and second modules 12,21 (as shown in Figure 3), the two supports 41 for the two aftertreatment system support assemblies 1 may be combined into a single part. Where the support 41 comprises a bracket, the bracket may comprise all features described in relation to the support 41.

Retaining means 42 may be provided for securing (or clamping) the aftertreatment system module 5 to the support 41. The retaining means 42 may be part of the support 41, or may be a separate element. The retaining means 42 may comprise a tensioning mechanism (not shown) for tightening/loosening the retaining means 42 and thereby adjusting a clamping load on the aftertreatment system module 5. The retaining means 42 may comprise at least one retaining strap, which may be made of metal. The at least one retaining strap may comprise a tensioning bolt as the tensioning mechanism. The vibration attenuator 43 may be disposed between the support 41 and the aftertreatment system module 5, to disrupt the transmission of vibrations from the engine 11 to the aftertreatment system module 5, and thereby to reduce the resulting noise emission. The vibration attenuator 43 may additionally serve to aid a secure clamping of the aftertreatment system module 5 by the support 41 and the retaining means 42.

The vibration attenuator 43 may be sandwiched between the support 41 and the module. The vibration attenuator 43 may be in direct contact with the support 41 and/or with the aftertreatment system module 5. Where retaining means 42 are provided, the vibration attenuator 43 may also be provided in the same manner between the retaining means 42 and the aftertreatment system module 5.

The vibration attenuator 43 may comprise a strip of material. Optionally, the vibration attenuator 43 may comprise a strip of fabric. The thickness of the material may be 1 mm to 5 mm, optionally 2 mm to 4 mm, optionally 3 mm. The width of the material may be 25 mm to 100 mm, optionally 40 mm to 85 mm, optionally 50 mm.

The vibration attenuator 43 may be subjected to surface temperatures of the aftertreatment system module 5 that may reach 400°C. Additionally, the vibration attenuator 43 may be subjected to thermal cycling associated with the engine 11 and aftertreatment system 10 operation. The support 41 and the retaining means 42 may expand and contract with the thermal cycling, which may amount to a few millimetres radially; the vibration attenuator 43 must be able accommodate any relative movement between component parts, as well as with any strain associated therewith. Therefore, the material of the vibration attenuator 43 may be chosen for its heat resistance and mechanical durability, as well as for its vibration attenuation properties. A medium density fibrous material may attenuate vibration passing through it by the conversion of mechanical energy (vibration) into heat through the excitation of micro-fibres or particles. However, if the material becomes too compressed, vibration may be more readily transmitted rather than being attenuated.

The material of the vibration attenuator 43 may comprise a gasket material. Suitable gasket materials for the vibration attenuator 43 include, but are not limited to: a fibreglass material, for example a compressed non-asbestos fibreglass material; a graphite coated glass cloth; a stainless steel foil graphite material; silicone coated Kevlar (TM); a graphite gasket material such as is available from Rich. Klinger Dichtungstechnik GmbH & Co KG; and Klinger Quantum, available from Rich. Klinger Dichtungstechnik GmbH & Co KG.

Optionally, the vibration attenuator 43 may comprise a glass fibre material. An example of a suitable glass fibre material is GW 304 Insulation Wrap, available from TBA Protective Technologies, Rochdale, Lancashire, United Kingdom. Again, the thickness of the material may be 1 mm to 5 mm, optionally 2 mm to 4 mm, optionally 3 mm. The width of the material may be 25 mm to 100 mm, optionally 40 mm to 85 mm, optionally 50 mm.

The level of vibration attenuation provided by the vibration attenuator 43 may be tuned, and optimised, by varying the clamping load applied by the support 41 and the retaining means 42 on the vibration attenuator 43 and the aftertreatment system module 5. As previously described, the clamping load may be adjusted using the tensioning mechanism on the retaining means 42. A clamping load that is too high may make the vibration attenuator 43 less effective, resulting in additional vibration from the engine 11 being transmitted between the support 41 and retaining means 42 and the aftertreatment system module 5, and therefore increased noise. A clamping load that is too low may result in vibration of the aftertreatment system module 5 itself, due to insufficient clamping of the aftertreatment system module 5; as well as resulting in increased noise, this may lead to the aftertreatment system module 5 becoming displaced, which may result in mechanical failure. Where there is more than one set of retaining means 42, the same clamping force may be used for all retaining means 42. Where the retaining means 42 comprises at least one retaining strap and the tensioning mechanism comprises a tensioning bolt, the tensioning bolt may be tightened to a torque of 5 Nm to 20 Nm, optionally 7.5 Nm to 12.5 Nm, optionally 10 Nm.

Industrial Applicability

The aftertreatment system support assembly 1 has industrial applicability in the field of internal combustion engines, and particularly in the field of diesel internal combustion engines having aftertreatment systems fitted to meet emissions regulations.

When installing the aftertreatment system 10 on the engine 11, the support 41 may be mounted on the engine 11. For example, the support 41 may be mounted on a cylinder head of the engine 11. As another example, the support 41 may be mounted on a flywheel housing, the flywheel being associated with the engine 11. The support 41 may, for example, be bolted to the engine 11, or it may be mounted on the engine 11 using other known suitable means. The support 41 may be mounted on the engine 41 before or after the aftertreatment system support assembly 1 is assembled.

To assemble the aftertreatment system support assembly 1, the vibration attenuator 43 may be disposed around the circumference of the aftertreatment system module 5 canister 40 at the locations where the aftertreatment module will contact the support 41 and the retaining means 42 (where retaining means 42 are provided). To facilitate assembly, the vibration attenuator 43 may be removably secured to the aftertreatment system module 5, for example via an adhesive or other securing means. Where an adhesive or other securing means is used, it may be temporary, as it is required only until the aftertreatment system module 5 is clamped to the support 41. Where an adhesive is used, the adhesive must be suitable for high temperature applications and flame resistant. A suitable adhesive type may be an elastic adhesive paste having thermal resistance. An example of a suitable adhesive is Teroson MS 93 9FR, available from Henkel Adhesive Technologies, Henkel Ltd. Further examples of suitable adhesives include 3M (TM) Scotch-Weld (TM) Epoxy Adhesive EC-2216 B/A, 3M (TM) Scotch- Weld (TM) Structural Adhesive EC-3984, and 3M (TM) Scotch-Weld (TM) Neoprene High Performance Contact Adhesive EC-1357, all available from 3M United Kingdom PLC.

The aftertreatment system module 5, having the vibration attenuator 43 disposed around it, may then be positioned on the support 41 and secured by the retaining means 42. The tensioning mechanism of the retaining means may be adjusted to a predetermined tightening torque to achieve a desired level of vibration attenuation.

Thus the vibration attenuator 43 may be applied to the surface of the aftertreatment system module 5 at locations where the aftertreatment system module 5 is restrained to the engine 11. The vibration attenuator 43 may ensure that there is no direct contact between the support 41 and the aftertreatment system module 5, or between the retaining means 42 and the aftertreatment system module 5.

Use of the aftertreatment system support assembly 1 of the present disclosure may lead to an overall engine noise reduction of more than 1dBA, when measuring engine sound following ISO 6798. This may be equivalent to an overall reduction of 24% in engine noise.

Embodiments of the disclosure are considered as set out in the following numbered clauses:

1. An aftertreatment system support assembly, comprising: an aftertreatment system module; a support configured to be mounted on an engine, the support further being configured to support the aftertreatment system module; and a vibration attenuator sandwiched between the support and the aftertreatment system module.

2. An aftertreatment system support assembly according to claim 1, wherein the vibration attenuator is in direct contact with the aftertreatment system module.

3. An aftertreatment system support assembly according to claim 1 or claim 2, wherein the vibration attenuator is in direct contact with the support.

4. An aftertreatment system support assembly according to any one of the preceding claims, further comprising retaining means for securing the aftertreatment system module to the support.

5. An aftertreatment system support assembly according to claim 4, wherein the vibration attenuator is further sandwiched between the retaining means and the aftertreatment system module.

6. An aftertreatment system support assembly according to claim 5, wherein the vibration attenuator is in direct contact with the retaining means.

7. An aftertreatment system support assembly according to any one of claims 4 to 6, wherein the retaining means comprises a tensioning mechanism.

8. An aftertreatment system support assembly according to claim 7, where the tensioning mechanism is tightened to a torque of 5 Nm to 20 Nm. 9. An aftertreatment system support assembly according to any one of claims 4 to 6, wherein the vibration attenuator is clamped to the aftertreatment system module by the support and the retaining means.

10. An aftertreatment system support assembly according to any one of the preceding claims, wherein the vibration attenuator comprises a strip of material.

11. An aftertreatment system support assembly according to claim 10, wherein the material is a fabric.

12. An aftertreatment system support assembly according to claim 10 or claim 11 , wherein the strip of material has a thickness of 1 mm to 5 mm.

13. An aftertreatment system support assembly according to any one of the preceding claims, wherein the vibration attenuator comprises a heat resistant material.

14. An aftertreatment system support assembly according to any one of the preceding claims, wherein the vibration attenuator comprises a gasket material.

15. An aftertreatment system support assembly according to any one of the preceding claims, wherein the support is configured to receive the aftertreatment system module.

16. An aftertreatment system support assembly according to any one of the preceding claims, wherein the support comprises at least one bracket.

17. An aftertreatment system support assembly according to any one of claims 4 to 6, or any one of claims 7 to 16 as dependent upon any one of claims 4 to 6, wherein the retaining means comprises at least one retaining strap.

18. An aftertreatment system support assembly according to any one of the preceding claims, wherein the vibration attenuator is wrapped around the aftertreatment system module.