Improvements in road cleaning vehicle rear suction assemblies

Abstract

A nozzle 23,24 for a rear suction assembly (20,fig.2) for a road cleaning vehicle (10,fig.1) comprises a nozzle housing 40 forming a nozzle chamber 41 extending and converging between a nozzle inlet 4

Description

Road cleaning vehicles (also referred to as road sweepers, street cleaners and the like) are commonly used to remove unwanted debris from streets. Typical road cleaning vehicles are disclosed in WO2015140546A1 and WO2023099284A1, which disclose road cleaning 10 vehicles comprising debris collection arrangements. The debris collection arrangements comprise suction conduits on either side of the vehicle and between the front and rear wheels for picking up debris from the road and delivering it to a container mounted on the vehicle chassis. Guides and rotating brushes underneath and to the side of the vehicle direct debris on the road towards the suction conduits. 15 Road cleaning vehicles can also include a rear suction assembly for handling heavy duty operations, such as cleaning dirt ingrained into the road surface on road construction sites, or on roads leading to or from construction sites. Rear suction assemblies are also useful when cleaning chemicals such as glycol and de-icing liquids from highways. In such 20 situations, heavy duty cleaning and washing of the road across the width of the vehicle is desired. A typical rear suction assembly comprises a chassis mounted on wheels with high pressure water jets applying water to the road and nozzles for drawing away debris removed from 25 the road surface by the water jets. The nozzles and water jets extend across the width of the vehicle to clean across the full width of the vehicle. The water jets are usually located to the rear of the nozzles and direct water forwards across the underside of the nozzles to achieve an appropriate angle of attack for driving dirt off the road surface. Water jets, such as rotating nozzle jets, can also be located in front of the nozzles to further assist with 30 removing dirt from the road surface. Replaceable skirts, which typically comprise flaps, are configured around the base of the nozzles for location adjacent to the road. CN108660995A discloses an exemplary rear suction assembly. However, further improvements are desirable in rear suction assemblies to ensure effective cleaning of the 35 road surface across the full width of the vehicle. 16 1025 Summary An object of the present invention is to provide a rear suction assembly for a road cleaning vehicle with improved cleaning of the road surface across the full width of the vehicle. A further objection is to provide such a rear suction assembly locatable behind the rear 5 wheels of the vehicle and meets the dimensional constraints of such a location. The present invention provides a separator element, road cleaning vehicle and rear suction assembly in accordance with the claims. 10 The present invention provides a rear suction assembly comprising an assembly frame for mounting to the road cleaning vehicle. First and second nozzles are mounted to the assembly frame, the first and second nozzles comprising nozzle inlets mounted adjacent to one another with a gap therebetween. A separator element is mounted in the gap between the first and second nozzles for dividing airflow between the first and second nozzle inlets. 15 The present invention provides a separator element for mounting in a gap between nozzle inlets of first and second nozzles of a rear suction assembly for a road cleaning vehicle, the separator element comprising a separator body. The separator body comprises indentations on either side in which the first and second nozzles are mounted. Alternatively 20 or additionally, the separator element comprises a divider body extending from the separator body past the nozzle inlets for at least partially separating flow between the first and second nozzles. The present invention also provides a road cleaning vehicle comprising the rear suction 25 assembly as disclosed herein. In accordance with the present disclosure, at least one guide wall helps to reduce the flow resistance of the nozzle, resulting in higher flowrate. It further helps to distribute the air flowrate along the width, making the flowrate distribution more even, or distribute more 30 flowrate at some important area, such as the two outer sides of the vehicle to ensure a beneficial reduction in water escapement.. A more even distribution of air velocity can thus be achieved. As a result, the suction force across the road area covered by the nozzles is sufficient to ensure that the required amount of debris and water is drawn through the nozzles. Areas of lower air flow velocity are avoided such that patches of uncleaned debris 35 and water do not remain on the road. Such patches would otherwise typically appear as 16 1025 streaks of excess water and debris along the road behind the vehicle in the locations where the lower air flow velocity is present in the nozzles. Generally, in the present disclosure, the rear suction assembly has been significantly 5 improved compared to those of the prior art to generate a sufficiently high air velocity across the full area of each nozzle. Features contributing to this effect include the walls within the nozzle, as well as the skirt around the bottom edge of the nozzle to improve air flow into the nozzle and the separator element / divider to reduce scavenging of air between first and second nozzles where they meet. In addition to providing more effective cleaning, 10 the increased air velocity makes the rear suction assembly more tolerant of differing setups, since it will work over a variety of heights and angles of the nozzles. In addition, in the present disclosure the nozzle has been slimmed down in comparison to the prior art to generate higher air speed. The nozzle has also been designed so that it can 15 fit in and around other parts of the vehicle, such as rear underrun and lighting. The present disclosure provides a nozzle for a rear suction assembly for a road cleaning vehicle, comprising a nozzle housing forming a nozzle chamber extending and converging between a nozzle inlet and a nozzle outlet. At least one guide wall is mounted in the nozzle 20 chamber forming a plurality of passageways for dividing air flowing through the nozzle chamber between the nozzle inlet and outlet. The present disclosure provides, in embodiments, a rear suction assembly comprising an assembly frame for mounting to the road cleaning vehicle and first and second nozzles 25 mounted to the assembly frame, wherein each of the first and second nozzles comprises the nozzle of the present disclosure. The rear suction assembly may further comprise the skirt of the present disclosure. The present disclosure provides a skirt for mounting around a nozzle inlet of at least one 30 nozzle of a rear suction assembly for a road cleaning vehicle. The skirt comprises a skirt body extending across a thickness between a lower inner edge for mounting proximal the nozzle inlet and a lower outer edge for mounting distal to the nozzle inlet. At least one of the inner and outer edges is curved. 16 1025 The present disclosure also provides a nozzle for a rear suction assembly for a road cleaning vehicle, the nozzle comprising a nozzle housing forming a nozzle chamber extending and converging between a nozzle inlet and a nozzle outlet, wherein the depth of the nozzle inlet is less than about 15% of the width of the nozzle inlet and / or the maximum 5 depth of the nozzle outlet is less than 50% of the width of the nozzle outlet. The present disclosure also provides a method of operating the rear suction assembly by applying a suction force to the nozzle to draw air therethrough. In the present disclosure the term “road” generally refers to a highway surface. However, it 10 will be appreciated that the term “road” also includes any other surface that the road cleaning vehicle travels over, such as a track or other off-highway surface. Brief Description of the Drawings By way of example only, embodiments of a road cleaning vehicle, rear suction assembly, 15 nozzle, skirt, separator element and methods in accordance with the present disclosure are now described with reference to, and as shown in, the accompanying drawings, in which: FIGURE 1 is a side elevation view of a road cleaning vehicle comprising a rear suction assembly in accordance with the present invention; FIGURE 2 is a rear perspective view of the rear suction assembly of Figure 1; 20 FIGURE 3 is a cross-section view across a width of the rear suction assembly of Figure 2; FIGURE 4 is a side view of a nozzle and skirt of the rear suction assembly of Figure 2; FIGURE 5 is an exploded perspective view of a nozzle of the rear suction assembly of Figure 2; FIGURE 6 is a magnified view illustrating an articulation mount and surrounding features of 25 the rear suction assembly of Figure 2; FIGURE 7 is a cross-sectional view illustrating the articulation mount and surrounding features of Figure 5; and; FIGURE 8 is a cross-sectional view illustrated a skirt of the rear suction assembly of Figure 2. 30 Detailed Description The present disclosure generally relates to various approaches to improving the air velocity through a nozzle of a rear suction assembly of a road cleaning vehicle. A slimmer nozzle, at least one guide wall separating the nozzle into passageways, a separator element 35 between nozzles and an improved skirt around the nozzle(s) can be implemented independently of one another to improve the distribution of air velocity across a rear suction assembly. 16 1025 Road cleaning vehicles are commonly used to remove unwanted debris from streets. A road cleaning vehicle 10 comprising a rear suction assembly 20 in accordance with the present invention is shown in Figure 1. The road cleaning vehicle 10 in this instance is a four-wheeled truck mounted sweeper 10 in the form of a driver operated vehicle. The road cleaning vehicle 10 comprises a front axle and corresponding front wheels 11 and a rear axle and corresponding rear wheels 12. An operator control station 13 is located towards the front of the vehicle. At the sides of the sweeper there are provided cleaning tools, such as cleaning brushes 14 and side nozzles 15. The side nozzles 15 provide a passageway for picking up debris from the road and delivering it to a container or hopper 17 mounted on the vehicle chassis 19. The suction force in the conduits is provided by a fan assembly that is arranged to create a negative pressure in the container 17. The conveyancing or suction force draws the debris from the suction conduits into the container 17 and once in the container 17, the debris is separated from the air by means of a separation system before the air is exhausted by the fan assembly to the atmosphere. The road cleaning vehicle 10 further includes the rear suction assembly 20 mounted behind the rear axle and rear wheels 12. The rear suction assembly 20 is usually located at least partially underneath the hopper 17 adjacent to the road or other such surface. The rear suction assembly 20 is configured to clean the road behind the rear wheels 12 and is particularly suited to heavy duty cleaning operations, such as when dirt is ingrained into a road surface. The assembly 20, illustrated in further detail in Figures 2 and 3, generally comprises an assembly frame 21 mounted to the road cleaning vehicle 10, particularly the chassis 19 thereof. The assembly 20 comprises at least one assembly wheel 22, preferably a plurality of wheels 22 as illustrated, mounted to the assembly frame 21 for supporting the assembly 20 on the road or surface over which the road cleaning vehicle 10 travels. The assembly 20 further comprises first and second nozzles 23, 24 mounted to the assembly frame 21 as illustrated in Figures 2 and 3. When the assembly 20 is mounted to the road cleaning vehicle 10, at least one conduit 25 or trunking connects the first and second nozzles 23, 24 to the fan assembly such that the fan assembly can be controlled to apply a suction force through the first and second nozzles 23, 24. Thus debris can be drawn in through the first and second nozzles 23, 24 and into the container 17 using the fan assembly. The assembly 20 is generally configured to extend perpendicular to the travel direction 5 of the vehicle 10. The travel direction 5 is that which extends from the front to the rear of the vehicle 10. Hence the assembly frame 21 is generally elongate perpendicular to the travel direction 5. The first and second nozzles 23, 24 are mounted adjacent to one another perpendicular to the travel direction 5. The rear suction assembly 20 preferably also includes at least one spray bar 18 for spraying water onto the road. The water from the at least one spray bar 18 may be particularly effective at removing ingrained dirt from the road, with the water and debris being drawn away by the first and second nozzles 23, 24. The at least one spray bar 18 may be mounted to the assembly frame 21 and / or first and second nozzles 23, 24 and may extend along the full width of the first and second nozzles 23, 24 (i.e. perpendicular to the travel direction 5). The at least one spray bar 18 may direct water in the forward direction such that it strikes the road directly underneath the first and second nozzles 23, 24 such that the water from the at least one spray bar 18 can be drawn up by the first and second nozzles 23, 24. Additional waterjets (not illustrated) may also be directed at the road between the rear wheels 12 and at least one assembly wheel 22 to further improve removal of dirt from the road. The water from these additional waterjets can also be drawn into the first and second nozzles 23, 24. The assembly frame 21 comprises a mounting frame 26 for mounting to the chassis 19. The mounting frame 26 may comprise a rigid bar 27, which may be configured to extend transverse to the longitudinal length of the chassis 19 and to the travel direction 5, with chassis connectors 28 at either end for connection to the chassis 19. The assembly frame 21 comprises at least one connecting rod and / or actuator 29, 30 for pivotally mounting the first and second nozzles 23, 24 and at least one assembly wheel 22 to the mounting frame 26. A central connecting rod 30 may be pivotally connected to the mounting frame 26 and pivotally connected to an articulation mount 31 of the assembly frame. The connecting rod(s) may comprise drag link(s) and the actuators may comprise pneumatic actuators The at least one connecting rod and / or actuator 29, 30 may enable the adjustment of the angle of nozzles 23, 24 with respect to the road and may control how close the nozzles 23, 24 are to the road. The at least one connecting rod and / or actuator 29, 30 may raise the nozzles 23, 24 from the road during transit (e.g. 200 mm from the road) and bring the nozzles 23, 24 closer to the road (e g. with the skirt 90 about 10 mm from the road). The at least one connecting rod and / or actuator 29, 30 may also assist in keeping the skirt 90 parallel to the road. In Figure 3 the mounting frame 26 and at least one connecting rod and / or actuator 29, 30 are hidden for the sake of clarity. The first and second nozzles 23, 24 are pivotally mounted to the articulation mount 31, as best illustrated in Figures 6 and 7. The articulation mount 31 comprises a frame pivot 32 to which the central connecting rod 30 is pivotally mounted and first and second nozzle pivots 33, 34 to which the first and second nozzles 23, 24 are pivotally mounted. The pivot axis of the frame pivot 32 is orthogonal to the pivot axis of the nozzle pivots 33, 34. The pivot axes of the nozzle pivots 33, 34 are parallel to one another. The articulation mount 31 comprises an articulation mount body 35 to which the frame pivot 32 and first and second nozzle pivots 33, 34 are mounted. The first and second nozzle pivots 33, 34 may comprise apertures through opposing ends of the articulation mount body 35 to which the first and second nozzles 23, 24 are pivotally mounted by bolts, as illustrated. As illustrated, the articulation mount body 35 may comprise a substantially rectangular cuboid with cylinders at either end, the apertures extending through the cylinders. The frame pivot 32 may comprise two plates extending from the articulation mount body 35 to which the central connecting rod 30 is pivotally mounted by bolts, as illustrated. The first and second nozzles 23, 24 are connected or mounted directly to one another only via the articulation mount 31. The first and second nozzles 23, 24 may be able to pivot around the articulation mount 31 such that they have different angles to the road. The at least one connecting rod and / or actuator 29, 30 may be adjusted by an operator to hold them in such an orientation. Therefore, the first and second nozzles 23, 24 can be adjusted to suit the camber of the road and bring them close to the road along their lengths, whilst maintaining a gap between the nozzles 23, 24 and the road for allowing air intake into the nozzles 23, 24. The at least one assembly wheel 22 may be mounted to the first and second nozzles 23, 24 and / or at least one connecting rod and / or actuator 29, 30 via wheel frames 36. The at least one spray bar 18 (not illustrated in Figure 2) may be mounted to the trailing side of the first and second nozzles 23, 24 directly and / or via the assembly frame 21 and / or wheel frames 36. The at least one spray bar 18 may comprise first and second spray bars mounted to the first and second nozzles 23, 24 respectively. The at least one spray bay 18 may be mounted along the width of the first and second nozzles perpendicular to the travel direction of the vehicle 10. The first and second nozzles 23, 24 are illustrated in further detail in Figures 3 to 6. The first and second nozzles 23, 24 comprises substantially the same parts and are substantially mirrors of one another, being symmetrical about the articulation mount 31. In the following, reference will be made to “the nozzle 23, 24” and thus the description may be applied to the first and / or second nozzles 23, 24. The same reference numerals have been applied in Figure 3 for the first and second nozzles 24. It will also be understood that the nozzles 23, 24 of the present disclosure can equally be applied in rear suction assemblies 20 having only one nozzle 23, 24 of the present disclosure (e g , without a further nozzle or with a further nozzle formed as in the prior art), although the first and second nozzles 23, 24 as shown in the Figures would be preferable The nozzle 23, 24 comprises a nozzle housing 40 forming a nozzle chamber 41 therein The nozzle housing 40 may be generally thin walled (e.g., by having a thickness of less than 5% or 10% of the width of the nozzle 23, 24), may be a substantially hollow body and may be formed of at least one plate as illustrated. In the present disclosure, reference to a “plate” means a substantially planar body, which may be formed of one plate or multiple stacked plates affixed together, such as by nuts, adhesive and / or rivets. The nozzle housing 40 may thus be formed of a plurality of plates fixed together or may be formed by moulding in one or more parts. The nozzle housing and chamber 40, 41 extend between a nozzle inlet 42 and a nozzle outlet 43. The nozzle chamber 41 is substantially sealed other than at the nozzle inlet and outlet 42, 43. The assembly 20 and / or nozzle 23, 24 is / are configured such that, in use, the nozzle inlet 42 is mounted adjacent to the road and / or the nozzle outlet 43 is located distal to the road compared to the nozzle inlet 42. The nozzle outlet 43 is in particular located as the highest part of the nozzle 42, 43. Hence the nozzle 42, 43 extends between the nozzle inlet and outlet 42, 43 along its height H. The nozzle 42, 43 extends across a width W, which is perpendicular to the height H. The nozzle 42, 43 extends across a depth D, which is perpendicular to the width W and height H. When the nozzle 42, 43 is mounted to the vehicle 10, the high H is substantially perpendicular to the road surface and perpendicular to the travel direction 5, the depth D extends substantially along the travel direction 5 and the width W extends substantially perpendicular to the travel direction 5 and substantially parallel to the road surface. The first and second nozzles 23, 24 are mounted next to one another so that their width W axes are coaxial, whilst their height H and depth D axes are parallel. The nozzle inlet and outlet 42, 43 may each comprise or form an opening from the nozzle housing 40 and the opening of the nozzle inlet and / or outlet 42, 43 is preferably along a plane parallel to the width Wand depth D. Thus, the nozzle inlet and / or outlet 42, 43 may form openings extending parallel to one another. The nozzle inlet 42 may be substantially rectangular (optionally with curved corners) and the nozzle outlet 43 may be substantially oblong (two semi circles separated by a rectangle). The nozzle housing and chamber 40, 41 are generally elongate by having a greater width Wthan depth D. In particular, the depth D of the nozzle inlet 42 may be less than about 15%, about 10% or about 7.5% of the width W of the nozzle inlet 42. The maximum depth D of the nozzle outlet 43 may be less than 50% of the width W of the nozzle outlet 43. The nozzle housing and chamber 40, 41 generally comprise a nozzle front 60, a nozzle rear 61 and first and second nozzle sides 62, 63 extending therebetween. The first and second nozzle sides 62, 63 may be generally curved and concave in the nozzle chamber 41. The nozzle front and rear 60, 61 may be substantially flat and planar. The nozzle housing and chamber 40, 41 converge between the nozzle inlet and outlet 42, 43. Hence the cross-sectional area (i.e., taken in the width W and depth D plane) of the nozzle inlet 42 is greater than that of the nozzle outlet 43. In one embodiment the inlet area for a single nozzle is 1,227m x 0.1 m = 0.1227 m2 and the outlet area for a single nozzle is 3.14 x 0.095m x 0.095m (radius 95mm) = 0 0283385 m2. The inlet / outlet area ratio is 0.1227 / 0.0283385 = 4.33. The convergence of the nozzle chamber 41 ensures a higher air speed at the nozzle outlet 43 than at the nozzle inlet 42 when the suction force is applied to the nozzle 23, 24. In order to achieve such convergence, the width W of the nozzle housing 40 converges between the nozzle inlet and outlet 42, 43. In particular, the width W of the nozzle outlet 43 may be less than about 50%, about 25% or about 20% of the width W of the nozzle inlet 42. As shown in Figure 4, although the overall nozzle chamber 41 converges from the nozzle inlet 42, the depth D of the nozzle chamber 41 preferably diverges between the nozzle inlet and outlet 43. In particular, the maximum depth D of the nozzle inlet 42 may be up to about 50% less, or about 40% less, than the maximum depth D of the nozzle outlet 43. The continuous divergence may provide for a smooth transition in shape and size without choking between the nozzle inlet and outlet 42, 43 such that the nozzle outlet 42, 43 can have a larger depth D and the correct shape for the at least one conduit 25 to fit around. In other embodiments, the depth D of the nozzle chamber 41 may not diverge such that the maximum depth D of the nozzle inlet 42 is substantially the same as the maximum depth D of the nozzle outlet 43. In the illustrated embodiment the nozzle housing and chamber 40, 41 do not converge continuously between the nozzle inlet and outlet 42, 43 and instead comprise step changes and regions of non-convergence therebetween. The nozzle housing 40 may comprise a hollow main nozzle section 45 forming and converging from the nozzle inlet 42. The main nozzle section 45 comprises front and rear nozzle plates 46, 47, which extend across the height H and width W of the nozzle 23, 24, adjoined by first and second main nozzle sides 48, 49, which substantially extend across the height H and depth D of the nozzle 23, 24. The front and rear nozzle plates 46, 47 and first and second main nozzle sides 48, 49 at least partially form the nozzle chamber 41 therebetween. The first and second main nozzle sides 48, 49 are preferably concave within the nozzle chamber 41 as illustrated, whilst the front and rear nozzle plates 46, 47 are preferably substantially flat and planar. The depth D of the main nozzle section 45 may diverge from the nozzle inlet 42. The nozzle housing 40 may comprise a hollow intermediate nozzle section 50 mounted to the main nozzle section 45. The intermediate nozzle section 50 has a converging width W and / or diverging depth D from the main nozzle section 45. The intermediate nozzle section 50 may be substantially tubular, with front and rear flat faces partially forming the nozzle front and rear 60, 61 and curved sides partially forming the first and second nozzle sides 62, 63. The nozzle housing 40 may comprise a hollow upper nozzle section 51 mounted to the intermediate nozzle section 50. The upper nozzle section 51 forms the nozzle outlet 43 and has a substantially constant cross-section, which may be the same oblong shape as the nozzle outlet 43. The upper nozzle section 51 may be substantially tubular, with front and rear flat faces partially forming the nozzle front and rear 60, 61 and curved sides partially forming the first and second nozzle sides 62, 63. The upper nozzle section 51 is configured for at least one conduit 25 to be mounted and / or sealed thereon such that the nozzle 23, 24 is connectable to the fan assembly and air drawn therethrough. The nozzle inlet and outlet 42, 43 each have a centre 55, 56, which is defined at the centre of the cross-sectional area (i.e., in a plane along their width Wand depth D). The centres 55, 56 are generally aligned along the depth D of the nozzle 23, 24. However, the centre 55 of the nozzle inlet 42 is offset from the centre 56 of the nozzle outlet 43. In particular, the centre 55 of the nozzle inlet 42 is closer to the second nozzle 24 than the centre 56 of the nozzle outlet 43. Such an arrangement allows for the nozzles 23, 24 to fit around components of the vehicle 10 and assembly 20. The nozzle 23, 24 comprises at least one guide vane or wall 65, 66, 67, 68, 69 mounted in the nozzle chamber 41 forming a plurality of passageways 70, 71, 72, 73, 74, 75. The passageways 70-75 are for dividing air flowing through the nozzle chamber 41 between the nozzle inlet and outlet 42, 43 and may in particular divide such air flow across the width W of the nozzle chamber 41. The at least one guide wall 65-69 may extend across the full width W of the nozzle chamber (i.e., between nozzle front and rears 60, 61) and / or along part of the height H of the nozzle chamber. Each passageway 70-75 may extend across the full depth D of the nozzle chamber 41, across part of the width W of the nozzle chamber 41 and / or across part of the height H of the nozzle chamber 41. The at least one guide wall 65-69 may be mounted to at least one of the nozzle front and rears 60, 61 and / or at least one of the front and rear nozzle plates 46, 47. In a particular embodiment, illustrated in Figure 5, the at least one guide wall 65-69 is mounted to the rear nozzle plate 47 and the rear nozzle plate 47 is removable from the front nozzle plate 46 (optionally also from the first and second nozzle sides 62, 63) with the at least one guide wall 65-69 connected thereto. Alternatively, the at least one guide wall 65-69 is mounted to the front nozzle plate 46 and the front nozzle plate 46 is removable from the rear nozzle plate 47 (optionally also from the first and second nozzle sides 62, 63) with the at least one guide wall 65-69 connected thereto. As a result, in embodiments in which there are a plurality of guide walls 65- 69, all can be removed simultaneously, thereby facilitating unblocking and maintenance. There may be applications in which the at least one guide wall 65-69 is not needed The operator may therefore remove from the nozzle 23, 24 the nozzle plate 46, 47 to which the at least one guide wall 65-69 is mounted and, since it is a mirror image, swap it with the corresponding nozzle plate 46, 47 of the second nozzle 24. This would leave the at least one guide wall 65-69 on the outside of the first and second nozzles 23, 24 and thus outside of the nozzle chamber 41. By way of example, in Figure 3 if the guide walls 65-69 are mounted to the front nozzle plates 46, the front nozzle plates 46 of the first and second nozzles 23, 24 could be swapped around such that the guide walls 65-69 are outside of the first and second nozzles 23, 24. The or each guide wall 65-69 may comprise a plate extending across the depth D of the nozzle chamber 41 The or each guide wall 65-69 extends from a proximal end 76 at or adjacent to the nozzle inlet 42 to a distal end 77 furthest from the nozzle inlet 42. The or each guide wall 65-69 may comprise a shorter straight and / or curved portion 78 extending from the proximal end 76 and a longer straight portion 79 extending therefrom to the distal end 77. Note that reference numerals 76, 77 are shown only for guide wall 65 and numerals 78, 79 are shown only for guide wall 67 in Figure 3 for the sake of clarity). The initial shorter straight and / or curved portion 78 assists in initially drawing air upwards, thereby promoting an even flow around the proximal ends 76 and the skirt 90. The at least one guide wall 65-69 may extend below and / or out of the nozzle inlet 42, by the proximal end(s) 76 being outside of the nozzle chamber 41, such that air is divided prior to entry into the nozzle chamber 41. The at least one guide wall 65-69 may extend to the distal end(s) along at least 50% of the height H of the nozzle chamber 41 from the nozzle inlet 42. In particular, the at least one guide wall 65-69 extends along at least 75% of the height H of the main nozzle section 45. Each passageway 70-75 extends from a passageway inlet 70a, 71a, 72a, 73a, 74a, 75a at or proximal to the nozzle inlet 42 to a passageway outlet 70b, 71b, 72b, 73b, 74b, 75b distal to the nozzle inlet 42. Each passageway 70-75 is substantially sealed from other passageways 70-75 other than at their inlets and outlets 70a-75a, 70b-75b. The passageways 70-75 comprise a central passageway 72, which may extend between two inner guide walls 66, 67 as illustrated. The passageway inlet 72a and outlet 72b of the central passageway 72 may be aligned with and / or extend across the centre 55, 56 of the nozzle inlet and / or outlet 42, 43. The passageways 70-75 also comprise at least one side passageway 70, 71, 73, 74, 75 located between the central passageway 72 and at least one of the first and second nozzle sides 62, 63 (e g , at least one of the first and second main nozzle sides 48, 49) The at least one side passageway 70, 71, 73, 74, 75 may comprise first and second outer side passageways 70, 75 extending between outermost guide walls 65, 69 and the first and second nozzle side 62, 63 respectively. The at least one side passageway 70, 71, 73, 74, 75 may comprise at least one inner side passageway 71, 73, 74 extending between the outermost guide walls 65, 69 and inner guide walls 66, 67, 68. A first inner side passageway 71 may extend between outer and inner guide walls 65, 66, a second inner side passageway 73 may extend between inner guide walls 67, 68 and a third inner side passageway 74 may extend between inner and outer guide walls 68, 69. At least one of the passageways 70-75 converges away from the nozzle inlet 42 and passageway inlets 70a-75a. In a convergent passageway 70-75 the passageway inlet 70a-75a will have a greater cross-sectional area (i.e., the area in the width W and depth D plane) than the passageway outlet 70b-75b. In the present disclosure, the term “rate of convergence” refers to the rate at which the cross-sectional area reduces along the passageway 70-75. Thus, a passageway 70-75 with a large difference in passageway inlet and outlet 70a-75a, 70b-75b areas will have a higher rate of convergence than a passageway 70-75 with a smaller difference in passageway inlet and outlet 70a-75a, 70b-75b areas. 16 1025 The at least one guide wall 65-69 and / or passageways 70-75 are configured to maintain the air velocity across the nozzle inlet 42 above a predetermined minimum air velocity when the suction force is applied tor draw air through the nozzle 23, 24. This ensures a 5 more even pick up of debris and water from the road. In particular, the at least one guide wall 65-69 may be configured such that, when a predetermined air suction flowrate is applied at the nozzle outlet 43 (e.g., by the fan assembly of the vehicle 10), the air velocity is higher in at least one passageway 70-75 10 compared to at least one other passageway 70-75. The passageways 70-75 are in particular configured such that, when a suction force is applied at the nozzle outlet 43, the air velocity is higher in the at least one side passageway 70, 71,73, 74, 75, preferably in at least one outer side passageway 70, 75, than the air velocity in the central passageway 72. The measurement of such air velocity may be determined from the air velocity across the 15 area of the passageway 70-75 at the distal end(s) of the at least one guide wall 65-69 to the nozzle inlet 42. Hence, when a suction force is applied at the nozzle outlet 43, the air velocity is higher in the side passageways 70, 71,73, 74, 75 closer to the nozzles sides 62, 63 than at the 20 centre 55 of the nozzle inlet 42. In prior art nozzles, the air velocity tends to be higher at the centre rather than at the sides because this is directly underneath the nozzle outlet 43. This leads to relatively low velocity at the nozzle edges, resulting in lines of uncleaned debris on the road behind the vehicle corresponding to the line of travel of the nozzle edges. The nozzles 23, 24 of the present disclosure eliminate such issues. 25 In order to achieve the differing velocities between the passageways 70-75, at least two of the passageways 70-75 have different volumes and / or cross-sectional areas at the nozzle inlet 42 and / or nozzle outlet 43 and / or the passageways 70-75 have different rates of convergence. 30 In particular, the rate of convergence of the central passageway 72 is greater than the rate of convergence of the side passageway(s) 70, 71,73, 74, 75. The rate of convergence in the inner side passageway(s) 71,73, 74 is greater than the rate of convergence in the outer side passageway(s) 70, 75. The outer side passageway(s) 70, 75 may have little or 35 no convergence. The result is that for an equally applied air velocity at the passageway outlets 70b-75b, the air velocity at the passageway outlets 70a-75a will be higher in the 16 1025 side passageway(s) 70, 71,73, 74, 75, with their lower rates of convergence, than the central passageway 72. The central passageway 72 has a larger cross-sectional area along its length than the side 5 passageway(s) 70, 71,73, 74, 75. Since the central passageway 72 is directly below the nozzle outlet 43, airflow therethrough is relatively even as compared to at the sides of the nozzle chamber 41, meaning that it may not be necessary to finely control the air velocity with more guide walls. 10 The cross-sectional area of the passageway inlet 72a of the central passageway 72 may be substantially larger, preferably at least twice as large, as the area of the passageway inlet 70a, 71a, 73a, 74a, 75a of the side passageway(s) 70, 71,73, 74, 75. The crosssectional area of the passageway outlet 72b of the central passageway 72 may be substantially larger, preferably at least twice as large, as the area of the passageway outlet 15 70b, 71b, 73b, 74b, 75b of the side passageway(s) 70, 71, 73, 74, 75. The cross-sectional area of the passageway inlet 72a and outlet 72b of the central passageway 72 may be larger and smaller respectively than the cross-sectional area of the nozzle outlet 43. In the rear suction assembly 10, the first and second nozzles 23, 24 are mounted such that 20 their second nozzle sides 63 are facing inwardly towards one another. Hence their second outer side passageways 75, particularly the passageway inlets 75a thereof, are located substantially adjacent to one another adjacent to the road. A gap 82 is formed between the first and second nozzles 23, 24, particularly between the nozzle inlets 42, second nozzle sides 63 and / or passageway inlets 75a. The width W of the gap 82 is variable based upon 25 the first and second nozzles 23, 24 pivoting relative to one another about the articulation mount 31. It is desirable for the gap 82 to be sealed such that air does not escape from between the first and second nozzles 23, 24. According to embodiments of the present invention, a 30 separator element 80 is therefore mounted in the gap 82 between the first and second nozzles 23, 24 for dividing airflow between the first and second nozzle inlets 42 and for substantially sealing the gap 82. The separator element 80 may comprise a resiliently deformable material, such as 35 polyurethane or rubber, and may generally be configured as a replacement part removable from the rear nozzle assembly 10. This is due to the separator element 80 being a part of 16 1025 the rear nozzle assembly 10 that contacts the road surface and thus is worn down in use. The separator element 80 may be moulded. The separator element 80 may not pivot with the first and second nozzles 23, 24 such that 5 the first and second nozzles 23, 24 are pivotable away from one another and the separator element 80. The separator element 80 may therefore be connected and / or mounted to the articulation mount 31 in a non-pivotable or fixed manner. The separator element 80 may be mounted underneath the articulation mount 31. The articulation mount 31 may thus comprise a separator mount 81 extending downwardly from the articulation mount body 35 10 to which the separator element 80 is mounted. The separator element 80 comprises a separator body 85, which comprises indentations 86, 87 on either side in which the first and second nozzles 23, 24 are mounted. The separator body 85 extends from the base of the indentations 86, 87 (shown best in Figure 15 7) along adjacent to or in contact with, the outside of the first and second nozzles 23, 24 (particularly of the first and second nozzle sides 62, 63) such that if the first and second nozzles 23, 24 pivot within a predetermined in use range, the separator body 85 will remain in contact with the first and second nozzles 23, 24. Therefore, the gap 82 remains substantially sealed even during pivoting of the first and second nozzles 23, 24. 20 The separator element 80 comprises a divider body 88 extending from the separator body 85 past the nozzle inlets 42 for at least partially separating flow thereunder between the first and second nozzles 23, 24. The divider body 88 may extend past the distal ends 76 of the guide walls 65-69. The divider body 88 may comprise concave side surfaces 83, 84 25 facing towards each of the first and second nozzles 23, 24 for promoting more continuous flow into the first and second nozzles 23, 24. The present disclosure further provides a skirt 90 for improving the drawing of air from outside of the first and second nozzles 23, 24 and into the first and second nozzles 23, 24. 30 The skirt 90 in particular improves the collection of air from above the lower edge of the skirt 90 and road, thereby improving the air velocity as the air travels around the skirt 90 and into the first and second nozzles 23, 24. As illustrated in Figures 3 and 4, the skirt 90 generally extends around the perimeter of the 35 bottom of the first and second nozzles 23, 24 and particularly around the perimeter of the nozzle openings 42 thereof. The skirt 90 may be a substantially rectangular annulus in top or bottom plan view. The skirt 90 may be releasably mounted to the first and second nozzles 23, 24 and / or assembly frame 40. The skirt 90 may comprise a resiliently deformable material, such as polyurethane or rubber, and may generally be configured as a replacement part removable from the rear nozzle assembly 10. This is due to the skirt 90 being a part of the rear nozzle assembly 10 that contacts the road surface and thus is worn down in use. The skirt 90 may be moulded. The skirt 90 may be split into at least first and second skirt sections 91, 92, separated at the junction between the first and second nozzles 23, 24 and adjacent to the separator element 80. Therefore, due to the separation, the first and second skirt sections 91, 92 can pivot with the first and second nozzles 23, 24. It will be appreciated that the skirt 90 of the present disclosure may only extend around one nozzle 23, 24, if applied to a vehicle 10 with only one nozzle 23, 24 The profile of the skirt 90 is best illustrated in Figure 8. Although Figure 8 only shows the profile of a side of the skirt 90, the profile preferably continues around the front, rear and other sides of the skirt 90 (i.e., all the way around the skirt 90). The skirt 90 comprises a skirt body 93 extending between across a thickness T between a lower inner edge 94 for mounting proximal and / or adjacent the nozzle inlet 42 and a lower outer edge 95 for mounting distal to the nozzle outlet 42. The skirt body 93 comprises a lower side 96 extending between the lower inner and outer edge 94, 95. The lower side 96 and lower inner and outer edges 94, 95 will periodically contact the road due to its unevenness and will be worn down in use. The skirt 90 further comprises a skirt mount 98 extending upwardly from an upper side 97 of the skirt body 93 The skirt mount 98 may comprise a lip and / or flange for engaging around the first and / or second nozzle 23, 24 for securing the skirt 90 in place, optionally via fasteners as shown in Figure 2. At least one of the lower inner and outer edges 94, 95 is curved and / or convex. The lower outer edge 95 may curve from the lower side 96 upwardly by at least 50% of the height H of the skirt body 93. Having the lower outer edge 95 curved helps to draw down air from above the base of the skirt 90, effectively scavenging such air. This increases the flowrate and velocity of air towards the gap between the skirt 90 and the road The radius of curvature of the lower outer edge 95 is preferably at least 10mm and more preferably in the range of 20 - 60mm. The lower inner edge 94 may curve from the lower side 96 continuously to adjacent the nozzle inlet 42. Having the lower inner edge 94 curved reduces any obstruction to air flow from between the skirt 90 and road and into the nozzle 23, 24, thereby increasing air velocity at the edges of the nozzle inlet 42. The radius of curvature of the lower inner edge 94 is preferably at least 10mm and more preferably in the range of 20 - 60mm. In accordance with the present disclosure, the slimmer nozzle 23, 24, at least one guide wall 65-69, separator element 80, skirt 90, can be implemented independently of one another to improve the distribution of air velocity across a rear suction assembly. However, in preferred embodiments the rear suction assembly 20 comprises all such features to significantly improve the distribution of air velocity thereacross. In use, the vehicle 10 travels along a road to be cleaned, with the cleaning brushes 14 brushing the road and directing debris into the side nozzles 15. The fan assembly draws the debris through the side nozzles 15 into the hopper 17. Simultaneously, the rear suction assembly 20 is operated by air also being drawing through the first and second nozzles 23, 24 and cleaning liquid, such as water, being directed onto the road and under the first and second nozzles 23, 24 by the spray bar 18 and / or additional waterjets. The rear suction assembly 20 thus cleans across the full width of the vehicle 10 The suction force through each nozzle 23, 24 draws air from the environment around the lower outer and inner edges 95, 94 of the skirt 90, with the former allowing the scavenging of air from above the skirt 90 itself. Water and debris on the road, as well as this air, is then drawn into each nozzle 23, 24, with the high velocity air assisting in drawing in the water and debris. The air, water and debris mix is drawn past the nozzle inlet 42, is divided by the at least one guide wall 65-69 between the passageway inlets 70a-75a, passes through the passageways 70-75 and leaves the passageways 70-75 via the passageway outlets 70b- 75b. The mix is then combined together after leaving the passageway outlets 70b-75b and exits the nozzle 23, 24 via the nozzle outlet 43. The arrangement of the passageways 70-75 ensures that sufficient air velocity is 5 maintained across the nozzle inlet 42 to draw in the debris and water. The separator element 80 cleanly divides the flow between the first and second nozzles 23, 24, whilst maintaining a seal on the gap 82 as the first and second nozzles 23, 24 pivot relative to the road. 16 1025

Claims

1. A rear suction assembly for a road cleaning vehicle comprising: an assembly frame for mounting to the road cleaning vehicle;5 first and second nozzles mounted to the assembly frame, the first and secondnozzles comprising nozzle inlets mounted adjacent to one another with a gap therebetween; anda separator element mounted in the gap between the first and second nozzles for dividing airflow between the first and second nozzle inlets.

102. The rear suction assembly of claim 1 wherein the first and second nozzles are pivotally mounted to the assembly frame, wherein the separator element does not pivot with the first and second nozzles such that the first and second nozzles are pivotable away from one another and the separator element.

153. The rear suction assembly of claim 1 or claim 2 wherein the assembly frame comprises an articulation mount to which the first and second nozzles are pivotally mounted, wherein the separator element is non-pivotally mounted to the articulation mount.20 4. The rear suction assembly of any of claims 1 to 3 wherein the separator elementcomprises a separator body.

5. The rear suction assembly of claim 4 wherein the separator body comprises indentations on either side in which the first and second nozzles are mounted; and / or256. The rear suction assembly of any of claim 4 or claim 5 wherein the separator element comprises a divider body extending from the separator body past the nozzle inlets for at least partially separating flow between the first and second nozzles.30 7. A separator element for mounting in a gap between nozzle inlets of the first and secondnozzles of the rear suction assembly of any one of claims 1 to 3, the separator element comprising a separator body, wherein the separator body comprises indentations on either side in which the first and second nozzles are mounted.

8. The separator element of claim 7 wherein the separator element comprises a divider body extending from the separator body past the nozzle inlets for at least partially separating flow between the first and second nozzles.5 9. A separator element for mounting in a gap between nozzle inlets of the first and secondnozzles of the rear suction assembly of any one of claims 1 to 3, the separator element comprising a separator body, wherein the separator element comprises a divider body extending from the separator body past the nozzle inlets for at least partially separating flow between the first and second nozzles.1010. A road cleaning vehicle comprising the rear suction assembly of any one of claims 1 to 6.16 1025

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