WO2014044571A1

WO2014044571A1 - Exhaust system mounting

Info

Publication number: WO2014044571A1
Application number: PCT/EP2013/068637
Authority: WO
Inventors: Thorsten Capelle; Andreas Kleinhenz; Andreas MUEHLDORFER; Peter NEISS; Stefan TITZSCHKAU
Original assignee: AGCO International GmbH
Current assignee: AGCO International GmbH
Priority date: 2012-09-20
Filing date: 2013-09-09
Publication date: 2014-03-27
Anticipated expiration: 2015-03-20

Description

EXHAUST SYSTEM MOUNTING

This invention relates to exhaust systems for vehicles, and in particular to such systems for agricultural and/or industrial tractors, which includes an exhaust gas treatment unit to reduce the level of gas contaminants to the legally required levels.

To meet emission standards, Diesel Particulate Filters (DPF) may be included in exhaust lines to remove high percentages of diesel particulate matter or soot from exhaust gases. Compared to SCR- Catalysers, these emission treatment means must be regularly refreshed to remove accumulated ash. This may be done by burning fuel in the DPF to heat the filter to particulate combustion

temperatures. As this thermal regeneration increases fuel consumption, however, it is preferred instead to use DPF units which are exchanged regularly (2000-3000 working hours). Ease of mounting for assembly and maintenance are therefore an important consideration.

International Patent Application WO 2010/069807 Al describes an exhaust system for an agricultural and/or industrial tractor having an internal combustion engine located in an engine compartment covered by an engine hood , the system including an exhaust gas treatment unit (which may include a DPF) located inside the engine compartment hood and having a main chamber fed by an inlet pipe which receives exhaust gases from the engine and an outlet pipe which passes treated gases into a final portion of the exhaust. The treatment unit is installed above the engine and orientated generally transverse relative to the tractor so that the exhaust gases pass through the main chamber of the unit in a direction generally normal to the driving direction of the tractor. In systems such as that of WO 2010/069807 Al, the treatment unit consists of three major parts, namely a substrate container component and two lateral exhaust gas guidance parts including ports for connection with the exhaust gas ducts. The three parts are connected with clamps.

In case of maintenance both exhaust gas guidance parts are disassembled and the substrate container is exchanged for reconditioning. The substrate container typically has weight of about 35 kg so this part is very heavy compared to other parts inside the engine bay which have to be maintained. In high HP range tractors, this unit is installed (according to the arrangement of WO 2010/069807 Al perpendicular to the driving direction) at a height level of more than 2 metres from the ground which is hard to reach for assembly and service staff. Accordingly a safe method of assembly is required including access with a crane etc.

Furthermore the position under bonnet requires a very narrow design to enable a narrow engine bonnet for improved view, and the weight of the unit requires a stiff connection to the chassis structure. Suitably, therefore, the unit is connected to the (heat insulating) wall between engine bay and cab.

A further requirement is to reduce tolerances within the assembly. As geometric freedom is already needed to mitigate thermal expansion, flexible connecting parts are provided. Due to the massive heat impact during regeneration (up to 550°C gas temperature), these parts only offer a limited position fault capability (rubber parts used in the intake system cannot be used due to temperature limits). The result is that additional position errors caused by assembly tolerances would make it impossible to connect the unit properly. Adjusting the system when assembled is restricted by limited access in the crowded engine bay.

Therefore an assembly must be provided to ease handling during production and service, preferably including a tolerance optimized positioning.

In accordance with the present invention there is provided a mounting assembly for a vehicle exhaust system component comprising:

a mounting plate with means for securing the component thereto; and

a first exhaust gas guidance part having a first opening shaped to cooperate with an inlet or outlet of the component and a second opening connectable to an exhaust gas duct;

wherein the first guidance part or mounting plate has an external projection which is received in a corresponding opening in the mounting plate or first guidance part when the two are assembled to thereby guide the relative positioning of the component and first guidance part. As will be described in further detail with reference to exemplary embodiments below, the use of a mounting plate (which term encompasses any structural arrangement supporting the component) with cooperating projections/openings enabling the positive location of the or each exhaust gas guidance part provides a secure mounting for a component such as a DPF, with a mounting process less likely to suffer the time-consuming and costly delays occasioned by incorrect assembly.

In one embodiment the external projection comprises a first sensor mounted through an aperture in the first gas guidance part, the sensor having a sensing portion located within the gas guidance part and a connecting portion providing means for external connection to the sensing portion, the connecting portion being disposed on an outer surface of the gas guidance part and passing through a respective first aperture in the mounting plate when the mounting plate and gas guidance part are assembled. This arrangement utilises the mounting plate to provide thermal shielding for the sensor wiring and connections which is of particular benefit during operation, especially during

regeneration.

Further features of the invention are recited in the attached claims to which reference should now be made.

The present invention will now be described, by way of example, with reference to the accompanying drawings in which:

Figure 1 shows an agricultural tractor fitted with an exhaust system including an exhaust gas treatment unit, with part of the engine compartment hood removed for clarity;

Figure 2 shows a perspective view of a gas treatment unit used in the exhaust system of Figure

Figure 3 shows a mounting assembly for the treatment unit of Figure 2;

Figure 4 shows an inverted view of part of the mounting assembly of Figure 3; Figure 5 shows a sectional elevation through the mounting assembly and treatment unit of

Figure 3 when assembled;

Figure 6 shows a sectional elevation through a part of an alternate embodiment of mounting assembly and treatment unit of Figure 3 when assembled; and

Figure 7 is an enlarged detail of part of Figure 6.

Referring to the drawings, an agricultural tractor 1 has an engine 2 mounted in an engine

compartment defined by an engine hood 2a part of which is cut away in Figure 1 for clarity. The engine has an exhaust which includes a turbo charger 3 and an engine braking throttle valve 4.

Exhaust section 5 is connected to a first exhaust gas guidance part providing an inlet of an exhaust gas treatment unit 10 which also has a second guidance part providing an outlet which is connected by exhaust section 5a to a generally vertically extending silencer 5b.

As shown in Figures 2 and 3, the exhaust gas treatment (DPF) unit 10 consists of three major parts, namely a substrate container 11 and two lateral air (exhaust gas) guidance parts 12, 13. Each of the guidance parts 12, 13 has a first opening into which an end of the DPF unit 10 is received, and a second opening 12a, 13a providing a port for connection with the exhaust gas ducts. The three parts are connected with clamps 14 (see also Figure 6).

The substrate container 11 of DPF unit 10 is, for cost reasons, a generally cylindrical non-customized part available in various diameters and lengths without any attachment means. Normally the DPF unit 10 is attached to supporting structures by using fastener straps 15 with threaded ends 15a which engage into bores of the supporting structure and are fixed by nuts 15b. To ensure the position of the DPF unit 10, a mounting plate 22 of the support structure 20 is provided with centring means 21 providing a cradle portion with a contour of the same inner diameter as the substrate container 11. The centring means 21 are welded to the mounting plate 22. This ensures that the relative position of the substrate container 11 and the support structure 20 is fixed in height (Arrow Y) and longitudinal direction (Arrow X). However, the position of the container 11 in the Z direction, and rotation of the container about the Z axis, is not fixed. This standard fixation arrangement may be suitable for use with DPF units having ports (for connection with the exhaust gas ducts) which are aligned with the axis of substrate container 11 (along Arrow Z) but in case of non-aligned ports especially (such as the arrangement of Figure 2) this rotation about the Z axis cannot be accepted, as a small degree of angular offset would result in a unacceptable lateral offset of the ports.

An alternative approach would be to design the substrate container 11 such as to prohibit rotation and movement relative to the supporting structure, but as already mentioned, the substrate container is a non-customized part and any changes thereto would massively increase costs. To provide a positioning means for the DPF unit 10 without impacting the general design of the substrate container 11, the two lateral exhaust gas guidance parts 12, 13 are provided with mating means 16, 17 which engage with apertures 35 in the mounting plate 22 of the support structure 20 to positively locate the two guidance parts 12, 13 (and hence the substrate container 11). In a first embodiment, the mating means 16, 17 are mating pins which are welded to the guidance parts 12, 13 during the existing welding procedure. These mating pins 16, 17 have different diameters to avoid rotated assembly (with the unit 10 rotated 180 degrees about the vertical Y axis). The mating pins 16, 17 engage in respective bores or recesses 35a, 35b of the mounting plate 22 of the support structure 20 whereby bore 35b is shaped as a slot extending in the lateral Z direction to enable thermal extension.

Although the mating pins 16, 17 are shown as generally cylindrical, it will be readily appreciated that any cross-sectional form may be used provided that there is a corresponding engagement with the openings or recesses 35a, 35b of the mounting plate 22 or any other part of the support structure 20 to positively locate the guidance parts relative to the plate. For example, the two lateral air guidance parts 12, 13 may be provided with rectangular mating parts (shaped like fitted keys) which are welded to the face side. These mating parts may then engage with vertical slots in the side parts 23 of the support structure 20. It will equally be understood that the arrangement may be reversed with projections from the mounting plate or any other part of the support structure 20 engaging recesses in the outer casing of the guidance parts. Also, both mounting plate and guidance part may have corresponding recesses with a separate mating part providing the projection extending into both recesses.

In addition to constraining movement of the lateral exhaust gas guidance parts 12, 13 (and thereby the substrate container) in the lateral Z direction, the rotation of the guidance parts 12, 13 relative to substrate container 11 /support structure 20 is also sufficiently limited.

The installation of the unit 10 may have differences caused by the size of the substrate container 11. For example, in a higher HP vehicle, the substrate container 11 is liable to be larger so that the width Wl of the fully assembled DPF unit 10 (see Fig 5) is greater than the distance Dl between the side parts 23 of the support structure 20 which are connected to chassis. As a consequence, the whole support structure 20 plus DPF unit 10 must be assembled or disassembled from the top.

Compared to the above, lower HP vehicles typically require a smaller substrate container 11 (using the same lateral air guidance parts 12, 13) so that the width Wl of the fully assembled DPF unit 10 is smaller than the distance Dl between the side parts 23 of the support structure 20 which are connected to chassis. This enables the DPF unit 10 to be assembled or disassembled from the top by only assembling or disassembling the mounting plate 22 of the support structure 20 plus DPF unit 10. In an alternative embodiment, shown particularly in Figures 6 and 7, the mating means 16, 17 are provided by first and second sensors 30, 31 which are fitted as part of a system to monitor and/or control performance of the exhaust system.

One or both of the sensors 30, 31 may be a temperature sensor measuring exhaust gas temperature needed for various controls (e.g. managing regeneration cycles). One or both of the sensors 30, 31 may be a pressure sensor for absolute pressure: pressure in the exhaust is used e.g. for engine management. One of the sensors 30, 31 may be a NOx Sensor: measuring nitrogen oxide in the exhaust gas is necessary to control urea injection in a selective catalytic reduction (SCR) catalyser installed in the exhaust line after the DPF.

Each of the sensors 30, 31 comprises a sensing portion 30a, 31 a which, when the sensor is fitted, is located in the exhaust gas flow passage defined by the guidance portions 12, 13. Each of the sensors 30, 31 additionally comprises a connection portion 30b, 31b by means of which the sensor is connected to external control and monitoring arrangements. For the sensor types listed in the preceding paragraph, the sensor connection portions 30b, 31b will typically comprise wires or cables. These would be vulnerable to the heat from the exhaust system (particularly during regeneration) but are substantially protected in the present arrangement by virtue of the mounting plate providing a thermal barrier between the connection portions and the exhaust gas transmission components.

In an alternative arrangement, the sensors 30, 31 may be components of a pressure differential measuring means, with both sensing and connection portions being simple pipes which are connected to a pressure differential sensor used to determine a pressure differential between intake and outlet of the substrate container 11. The higher the differential is, the more particulates/ashes are trapped in the DPF (load condition). This is used to control active regeneration (by injecting and burning fuel).

Referring particularly to Figure 7, a sensor 31 is mounted to the guidance portion 13 through a mounting collar 34 which is preferably welded to the upper surface of the portionl 3 (although other fixing methods such as press-fitting or gluing may be used). The sensing portion 31a and connection portion 31 b j oin at an attachment portion 31c which has a threaded outer surface 31 d which engages with correspondingly threaded bore in the mounting collar 34 to fixedly mount the sensor 31 in the collar 34. A hexagonal portion 31e is provided to enable the connection to be tightened.

The collar 34 is received in a corresponding aperture 35 in the mounting plate when the DPF unit 10 is mounted on the mounting plate 22. The relative sizes of the collar and aperture is preferably such as to provide a clearance fit, giving positive positioning of the collar relative to the plate whilst still permitting extraction as the DPF unit is removed for replacement of the substrate container. One of the mounting plate apertures is suitably shaped as a slot extending in the lateral Z direction to allow for thermal extension of the DPF unit in operation.

The mounting collars 34 of the two sensors (and their respective mounting plate apertures) may have different diameters or shapes to avoid rotated assembly (with the unit 10 rotated 180 degrees about the vertical Y axis).

Claims

1. A mounting assembly for a vehicle exhaust system component comprising:

a mounting plate with means for securing the component thereto; and

wherein the first guidance part or mounting plate has an external projection which is received in a corresponding opening in the mounting plate or first guidance part when the two are assembled to thereby guide the relative positioning of the component and first guidance part.

2. An assembly as claimed in claim 1, wherein the mounting plate includes a cradle portion shaped to receive the exhaust system component and prevent movement thereof in first and second mutually orthogonal directions, and wherein the guidance part when assembled to the mounting plate limits movement of the exhaust system component in a third direction orthogonal to the first and second directions.

3. An assembly as claimed in claim 1 or claim 2 having a second exhaust gas guidance part, wherein the two guidance parts provide an inlet to and an outlet from the exhaust system component.

4. An assembly as claimed in claim 3 wherein an external projection and corresponding opening is provided between each guidance part and the mounting plate.

5. An assembly as claimed in claim 4 wherein the external projection and corresponding opening arrangement differ in size for each guidance part.

6. An assembly as claimed in claim 4 or claim 5, wherein one of the corresponding openings is a slot extending generally in an axial direction of the exhaust system component when mounted.

7. An assembly as claimed in claim 1 or claim 2 wherein the external projection comprises a first sensor mounted through an aperture in the first gas guidance part, the sensor having a sensing portion located within the gas guidance part and a connecting portion providing means for external connection to the sensing portion, the connecting portion being disposed on an outer surface of the gas guidance part and passing through a respective first aperture in the mounting plate when the mounting plate and gas guidance part are assembled.

8. An assembly as claimed in claim 7, wherein the assembly includes a first external collar disposed about the connecting portion of the first sensor on the outer surface of the gas guidance part which collar is a clearance fit in the mounting plate first aperture.

9. An assembly as claimed in claim 7 or claim 8, wherein the first sensor is a temperature sensor, a pressure sensor, or a nitrogen oxide measurement sensor.

10. An assembly as claimed in claim 7 or claim 8, further comprising a second sensor, wherein the first and second sensors together comprise pressure differential determination means.