GB2520066A - Air intake assembly and duct therefor - Google Patents

Abstract

An elongate air duct 4 for mounting on the cab 1 of a truck as part of an air intake assembly 8 comprising of moulded plastics material and has a first air intake end and a second air outlet end. In section transverse to its length, the duct is formed by opposed widthwise walls (17, 18 Figs. 4a-d) and by opposed end walls (20, 21). The opposed widthwise walls are of greater length as seen in said section than the end walls. Along its length, the duct has at least one first region (14, 16 Fig. 3) in which the interior of the duct is transversely sub-divided by two laterally spaced first partitions (31, 33) each of which defines with the adjacent end wall of the duct and intervening portions of the widthwise walls respective first tube formations (10 Fig. 3) extending along the duct. Each first tube formation is formed by a moulded portion of a said widthwise wall that extends inwardly of the duct to contact the opposed widthwise wall. The duct of the present application provides a rigid structure to reduce the noise due to vibration at certain engine revs.

Description

Air Intake Assembly and Duct Therefor The present invention relates generally to air intake assemblies as provided on trucks to provide air to a turbocharger associated with an engine of the truck. The invention relates more particularly to an elongate duct for use in forming a so-called high-level' air intake assembly for a truck, to such air intake assemblies, and to trucks fitted therewith.

As the name suggests, a "high level" air intake assembly on a truck is one for which the air intake itself is provided at an elevated level on the truck. Such "high-level" air intake assemblies have the advantage that they take in air that is much less likely to have entrained water spray, dust or other particulate matter than is the case for air intake assemblies provided much closer to the ground. Thus "high-level" air intake assemblies have particular (but not necessarily) sole application for trucks that are likely to be driven along dust-laden roads or in frequently encountered wet conditions.

"High Level" air intake assemblies have the additional advantage of providing cooler air than a "low level" intake that is near the engine of the truck.

Typically, the air intake of such a "high-level" air intake assembly is mounted on the roof of the cab of the truck and the assembly incorporates an elongate duct mounted on the rear of the cab for feeding air from the air intake to the turbocharger via an air filter unit.

Trucks are now being designed to comply with Euro 6 requirements. Previously the standard was Euro 5. The difference in the standards relates to sound and exhaust emission levels so that changes made in going from a truck meeting the Euro 5 standard to one meeting the Euro 6 standard are primarily to the engine of the truck and associated components that treat exhaust gas. As such, other components designed for a truck complying with the Euro 5 standard may be used on one complying with Euro 6. This has obvious advantages for economy of truck manufacture.

We have however found that a "high-level" air intake assembly designed for a truck complying with the Euro 5 standard, when used in a truck complying with the Euro 6 standard, gives rise to noticeable noise levels in the cab of the vehicle above the general sound level generated by the truck. We have found this "noticeable noise level" to be caused at certain rpm values of the engine by vibration of the elongate duct in the "high-level" air intake assembly. This vibration may also have been generated when the air intake assembly was employed in a Euro 5 vehicle but remained unnoticed due to the generally higher levels of noise generated by such vehicles.

It is therefore an object of the invention to obviate or mitigate the abovementioned disadvantage.

According to a first aspect of the present invention there is provided an elongate air duct for mounting on the cab of a truck as part of an air intake assembly, wherein the elongate duct is of moulded plastics material and has a first, air intake end and a second, air outlet end wherein, (i) in section transverse to its length, the duct is formed by opposed widthwise walls and by opposed end walls, with said opposed widthwise walls being of greater length as seen in said section than said end walls, (U) along its length, the duct has at least one first region in which the interior of the duct is transversely sub-divided by two laterally spaced first partitions each of which defines with the adjacent end wall of the duct and intervening portions of the widthwise walls respective first tube formations extending along the duct, each of which is formed by a moulded portion of a said widthwise wall that extends inwardly of the duct to contact the opposed widthwise wall.

The invention further provides an air intake assembly comprising an air duct as defined for the first aspect fitted, at its air inlet end, with an air intake head.

Also provided by the invention is a truck provided with an air intake assembly as defined in the previous paragraph, the duct being mounted on the rear of the cab and the air intake head being mounted on the roof of the cab. The truck may be a rigid vehicle with a cargo carrying compartment, i.e. of the type described above. The truck may be one complying with the Euro 6 standard.

We have found that a "high-level" air intake assembly of the invention generates less of the aforementioned vibration than the prior assembly as used on trucks complying with the Euro 5 standard. It is believed that the benefits of the invention are attributable to the enhanced rigidity 01 the duct as provided by the internal structure of the duct and more particularly by the tube formations constructed by virtue of a moulded portion of a widthwise wall extending internally of the duct to meet the opposed wall.

Since the duct has (as seen in transverse cross-section) a width greater than its depth, the duct has the advantage that it can have the required internal volume for air flow whilst still being a "relatively liar' structure. This is of particular advantage in rigid cargo carrying trucks of the type having a load carrying enclosure with its front face located a short distance behind the rear face of the cab. More particularly, the "relatively flat" nature of the duct allows the front face of the lead carrying enclosure to be positioned relatively close to the cab so as to maximise cargo carrying volume for a given overall longth of the vehicle. This is in contrast to other solutions to the problem to rigidify the duct, e.g. the use of circular section tubes, which might require to front face of the cargo carrying enclosure to be positioned further back (than is the case for the present invention) so that for a given overall length of the truck cargo carrying capacity would be reduced.

A further advantage of the duct of the invention is that it may be produced economically by rotational moulding.

As indicated above, the duct of the assembly includes a first region in which the interior of the duct is sub-divided by two laterally spaced partitions which define, at each side of the duct, a first tube formation within the duct. Each of these partitions is formed by a moulded portion of a widthwise wall that extends inwardly of the duct to contact the opposed widthwise wall. Each such partition may be of externally opening, generally U-shaped cross-section and is preferably such that the limbs of any one U' are parallel to each other. There may be a two or more such first regions spaced from each other along the length of the duct. The or each such first region may be further sub-divided by at least one second partition that defines further (second) side-by-side tube formations between the laterally outer first tube formations. There may be a single second partition that sub-divides at least part of the first region into two side-by-side second tube formations. More preferably there are, within the first region, two longitudinally spaced second partitions that definc an upstream side-by-side pair of second tube formations and a downstream side-by-side pair of second tube formations.

In an alternative embodiment, there is (in the first region) at least one set of a plurality (preferably two) of second partitions across the width of the first region. Within the first region there may be longitudinally spaced sets of said plurality of second partitions (i.e. an upstream set and a downstream set).

The provision of two of the first regions each formed with side-by-side second tube formations enhances the rigidity of the duct.

The invention will be further described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a view from the rear of a cab of a truck fitted with an air intake assembly in accordance with the invention; Fig. 2 is a view of the air intake assembly from the same side as seen in Fig. 1; Fig. 3 is a view of the air intake assembly from the opposite side thereof; Figs. 4(a)-(d) are sections of the air intake assembly shown in Fig. 3 taken along the lines A-A, B-B, C-C, and D-D respectively, the sections being to an enlarged scale as compared to Fig. 3; and Fig. 5 is a plot of noise levels vs rpm for comparison of an air intake assembly of the invention and a prior art air intake assembly as both fitted to a truck meeting the Euro 6 standard.

Fig 1 illustrates the cab 1 of a truck considered for the purposes of the present description to be a rigid vehicle having an enclosed cargo carrying body (not shown) which is positioned with its leading face a short distance rearwardly of the cab 1 and which may extend to an overall height greater than that of cab 1. Again for the purposes of the present description, the truck is considered to comply with Euro 6 requirements.

As further shown in Fig. 1, a "high level' air intake assembly 2 in accordance with the invention is mounted on the rear side 01 cab 1 and serves to teed air trom above cab 1 to a filter unit 3 which in turn supplies air to a turbocharger (not shown) of the vehicle.

This air intake assembly 2 includes a generally vertical, elongate duct 4 of moulded plastics material (e.g. polyethylene) located in the aforementioned space between the rear of oab 1 and front of the cargo carrying body and mounted on the cab at three fixing points 5-7 as shown. At its upper (air inlet) end, duct 4 is fitted with an air intake head 8 which is seated, and mounted, on the roof of cab 1. At its lower (air outlet) end duct 4 is connected to the filter 3 by a connector unit 9.

Reference is now made to Figs. 2-4 for a more detailed explanation of the construction of air intake assembly 2 and more particularly the duct 4 thereof.

As described more fully below, duct 4 is internally structured to include a plurality of relatively long tube formations 10 and a plurality of relatively short tube formations 11 and 12, all of said tube formations 10-12 extending longitudinally of the duct 4 and imparting a degree of rigidity thereto that serves to reduce noise levels that would otherwise result from vibration of the air duct assembly 2.

For the purposes of explaining its internal structure, duct 4 is considered to be sub- divided along its length into tour regions identified in Fig. 3 by reference numerals 13- 16 going in the upstream to downstream direction of air flow along the duct 4.

Within region 16 are two of the longer tube formations 10 provided generally parallel to each other and located one at each laterally outer side of the region 16 (see also Fig. 4d). Also within region 16 are two of each of shorter tube formations 11 and 12. The two tube formations 11 are arranged as a side-by-side pair located at the upstream end of region 16. Similarly the two tube formations 12 are also arranged as a side-by-side pair, but positioned at the downstream end of region 16. The tube formations 11 and 12 are the same length as each other and less than half the length of tube formations so, as will be appreciated from Fig. 3, the downstream ends of tube formations 11 are spaced longitudinally from the upstream ends of tube formations 12 (see also Figs. 4(c) and 4(d)).

The region 14 is generally similar configuration to that of region 16 and will thus not be described in further detail.

With regard to regions 13 and 15, and as will be appreciated from Fig. 3 and Figs. 4 (a) and (b), these regions are effectively continuous across their widths without sub-division to tube formations 10-12 as described above for regions 14 and 16.

Further consideration will now be given to the manner in which regions 14 and 16 are configured and structured.

For the purposes of explanation, duct 4 is considered to have (as seen in the transverse sections of Figs. 4(a)-(d)) a front face 17 (i.e. the face adjacent cab 1), a rear face 18 and side walls 20 and 21.

As shown in Fig. 2, the rear face 18 of the duct 4 is formed with three generally parallel moulding features 22-24 which are seen as shallow channels from the exterior of duct 4 and which form corresponding ribs 25-27 respectively projecting into the interior of the duct 4. Moulding formations 22 and 24 are the laterally outermost of these moulding formations and are spaced from the respective adjacent side walls 20 and 21 of the duct 4 by the same distance. Moulding formation 23 extends centrally between moulding formations 22 and 24. All of moulding formations 22-24 are of generally constant depth along their length so that ribs 25-27 are correspondingly of constant height.

Formed along the length of the front face 17 of the duct 4, are three further moulding formations 28-30 which face the moulding formations 22-24 respectively. Moulding formations 28-30 are again seen as channels when viewed from the exterior of the rear face of the duct 4 and project into the interior of the duct in the form of ribs 31-33 respectively. However, as compared to the moulding formations 22-24 which are of constant depth along their length (and give rise to internal ribs 25-27 of constant height), the moulding formations 28-30 are of varying configuration along their lengths and give rise to ribs 31-33 of varying height.

Within duct regions 14 and 16, the moulding formations 28 and 30 are (as seen in the section of Fig. 4(d)) of externally opening, generally U-shaped configuration (the limbs of any one "U" being parallel to each other) and are of a depth such that (within the duct 4) the ribs 31 and 33 generated by moulding formations 28 and 30 respectively extend into contact with the ribs 25 and 27 respectively. For convenience, these portions of ribs 31 and 33 that are formed into the U-shaped section and extend into contact with ribs 25 and 27 are referenced in Fig. 4 as 31 and 33. It will thus be appreciated that the longer tube formations 10 are defined by this contact of the rib portions 31: and 33 with the ribs 25 and 27, the tube formations being defined also by the adjacent side walls 20, 21 of the duct 4 and the intervening portions of the front and rear faces 17 and 18 thereof.

Within duct regions 14 and 16, the rib 32 (which runs centrally between ribs 31 and 33) is configured to define the two side-by-side pairs of shorter tube formations 11 and 12.

More particularly, within each region 14 and 16 the rib 32 has longitudinally spaced upstream and downstream portions 32u and 32d which are of the same U-shaped configuration as rib portions 31: and 33. Thus, rib portions 32u and 32d extend across the duct 4 to make contact with the opposed rib 26. Between these upstream and downstream portions 32u and 32d, there is an intermediate portion of the rib 32i that is of lesser height and does not extend across the duct to rib 26. Thus, the upstream side-by-side pair of short tube tormations 11 is defined by the positioning of rib portion 32u between the ribs 31 and 33. Similarly, the downstream side-by-side pair of tube formations 12 is defined by the positioning of rib portion 32'd between the ribs 31' and 33. Centrally within the region 14 and 16, the lower height of intermediate rib portion 32i means that there is no partitioning of the duct 4 between the ribs 31' and 33.

The illustrated structure of duct 4 may be produced economically by rotational moulding.

To illustrate the benefit of the invention, a truck complying with Euro 6 requirements was fitted (at the rear of its cab) with an air intake assembly in accordance with the invention and an identical truck was fitted (again at the rear of its cab) a prior art air intake assembly as previously fitted to the cabs of DAF LF45 and LF55 trucks complying with Euro 4 and Euro 5 requirements. The duct of this prior air intake assembly was generally of the same overall length, width and depth as the duct in accordance with the invention and had identically positioned fixing points. The cross-section of the prior duct was, along its entire length, generally similar to the section shown in Fig 4a save that there were no moulding formations 22 and 24 (nor corresponding ribs 25 and 27) and there was an additional moulding formation 23 (and corresponding rib 26) on lace 17.

For each of the Euro 6 trucks tested, noise levels (db) within the cab were monitored over a range of rpm values of the truck's engine (as shown on the truck's tachometer).

The results are shown in the graph of Fig. 5 which is a plot of noise levels (on the ordinate axis) vs rpm value. In Fig. 5, the lower trace was the one obtained for the truck fitted with the air intake assembly in accordance with the invention.

As will be appreciated from Fig. 5, the noise levels measured for the truck fitted with the air duct assembly in accordance with the invention were, over most of the rpm range measured (ca 500-2500 rpm), lower than those for the truck fitted with the prior art air duct assembly, although for the sake of completeness it is mentioned that the values were similar between 800 and 900 rpm.

It will be appreciated that a number of modifications may be made to the construction of duct 4 described above. Thus, for example, the internal configuration of the duct 4 may be such that there are three of the short tube formations 11 and/or 12 across the width of the regions 14 and 16. This may be achieved by providing two generally parallel moulding formations 23 on face 18, and correspondingly two mould formations 29 provided on face 17. Additionally, the two ribs 32 formed by moulding formations 29 would be formed into sections 32'i and 32d as described above to form three side-by-side tube formations 11 and 12.

In a further modification, the tube formationsi 0 are retained but there is no further sub-division of the duct to provide the second tube formations 11 and 12.

Claims (12)

1. CLAIMS: 1. An elongate air duct (4) for mounting on the cab (1) of a truck as part of an air intake assembly (8), wherein the elongate duct (4) is of moulded plastics material and has a first, air intake end and a second, air outlet end wherein, (i) in section transverse to its length, the duct is formed by opposed widthwise walls (17, 18) and by opposed end walls (20, 21), with said opposed widthwise walls (17, 18) being of greater length as seen in said section than said end walls (20, 21), and (ii) along its length, the duct (4) has at least one first region (14, 16) in which the interior of the duct is transversely sub-divided by two laterally spaced first partitions (31!, 33) each of which defines with the adjacent end wall (20, 21) of the duct (4) and intervening portions of the widthwise walls (17, 18) respective first tube formations (10) extending along the duct, each of which is formed by a moulded portion of a said widthwise wall that extends inwardly of the duct to contact the opposed widthwise wall.
2. 2. A duct as claimed in claim 1 wherein said first region (14, 16) has extending along its length between said first partitions (31!, 33') at least one second partition (32u, 32d) formed by a moulded portion of a widthwise wall that extends inwardly of the duct (4) to contact the opposed widthwise wall, said second partition defining second tube formations (11, 12) between said first tube formations.
3. 3. A duct (4) as claimed in claim 2 wherein said at least one second partition (32u, 32d) defines two side-by-side second tube formations (11, 12).
4. 4. A duct as claimed in claim 2 or 3 wherein said at least one second partition (32u, 32d) is provided midway between said first partitions (31', 33) as seen in said transverse section of the duct (4).
5. 5. A duct as claimed in any one of claims 2 to 4 wherein there are two of said second partitions (32u, 32d) in said first region (14, 16) and said two second partitions (32u, 32'd) are longitudinally spaced from each other along the length of the first regions (14, 16), said two second partitions (32'u, 32d) defining two longitudinally spaced, side-by-side pairs of said second tube formations (11, 12).
6. 6. A duct (4) as claimed in claim 2 wherein there is a plurality of said second partitions (32u, 32d) across the width of said first region (14, 16).
7. 7. A duct (4) as claimed in claim 6 the said first region (14, 16) there is an upstream set of said plurality of said second partition (32u) and a downstream set of said plurality of said second partitions (32d).
8. 8. A duct as claimed in any one of claims 1 to 7 wherein there are two of said first regions (14, 16) along the length of the duct (4) and the adjacent ends of said first regions (14, 16) are longitudinally spaced from each other such that between said two first regions there is a second region (15) of the duct (4) in which there is no internal partitioning.
9. 9. A duct as claimed in any one of claims 1 to 8 wherein said first partitions (31, 33!) and said second partitions (32u, 32'd), if present, are of parallel-linked, outwardly opening U-shaped configuration.
10. 10. An elongate air duct (4) for mounting on the cab (1) of a truck as part of an air intake assembly (8) substantially as hereinbefore described with reference to Figs. 2 to 4 of the accompanying drawings.
11. 11. An air intake assembly comprising a duct as claimed in any one of claims Ito 10 fitted with an air intake head.
12. 12. A truck provided with an air intake assembly as claimed in claim 11, sad duct being mounted on the rear of the cab and said air intake head being mounted on the roof of the cab.