WO2004078561A1 - Means for redirecting tyre spray - Google Patents

Abstract

Means for redirecting tyre spray from a moving road vehicle under wet or dusty conditions, comprises a modified mudguard (102) mounted in a position surrounding an upper part of at least one tyre (101), the mudguard (102) having a leading end, directed towards the direction of motion of the road vehicle, a trailing end, the mudguard (102) including means to accept air from a zone of air collision (108) situated, when vehicle in motion, at an approximately defined region about the at least one tyre (101), and means to divert the accepted air sideways and inwardly to an exit portal underneath the vehicle so that the redirected tyre spray does not present a road hazard.

Description

TITLE MEANS FOR REDIRECTING TYRE SPRAY

FIELD

This invention relates to means for redirecting splash and spray (also dust) from vehicles, more particularly spray and dust that is raised from tyres of moving vehicles on wet or dusty roads.

BACKGROUND

Main roads and motorways (turnpikes) become dangerous under conditions of poor visibility and collisions sometimes involving numbers of vehicles can result. Poor visibility can result from rain, snow, ice, fog, or dust but one of the principal and locally intense sources is spray thrown up from wet roads by other vehicles. Most car drivers have found that so much spray can be distributed from the tyres (and the body) of a moving truck on a wet road that it is almost impossible to approach or pass that truck. Spray from around a moving vehicle is laden with particulate matter that scratches windshields of following vehicles. It is also likely to include salt, and in particular oil droplets from deposits on the road, which smear the windscreen and further detract from visibility. Motor cyclists are generally quite unable to wipe their visors while in the act of passing a truck and coping with the pressure wave (like a boat's bow wave) that the truck develops. Furthermore, the truck driver finds it difficult to see backwards in his mirror through the spray in order to view overtaking vehicles.

Factors involved in throwing up spray include the road surface and the amount of water on it, the number of tyres on a vehicle, wheel loading, tyre (tread) configuration, mudguard configuration, and truck body aerodynamics including the often broken profile beneath the truck and the space behind the truck. Past innovations have provided a number of partial and generally unsatisfactory solutions such as the provision of bristles or modified surfaces facing the tyre surfaces inside mudguards, research into improving truck aerodynamics and hence fuel consumption, and has also contributed to aircraft tyre studies related to landing on wet runways. At this time, many trucks do not include suitable mudguards at all.

In many ways, the problem of dust on unsealed roads, thrown up in a similar manner by vehicles, is an analogous problem probably amenable to the same solution, and it would be an advantage for traffic safety, near-highway air conditions, and road wear if the amount of dust could also be minimised. This subject matter has attracted much interest over the years. Some documents carrying improvements in the area of spray and mist elimination and/or diversion include:

Silvey (GB 2378166) describes a device to suck moisture-laden air from a mudguard surrounding each wheel through a connecting tube and separate the water from air within a cyclone device. The water then drips onto the road. Others cited herein lie in the "spray diversion" group. US 3743343 Grote Jr describes an add-on air diversion device that exposes the wheel area to a stronger overall draft from the front, and a downwardly directed "tail" that forces the collected spray against the roadway. GB 2383986 Nock builds air intakes into the front of a vehicle (car or truck) and carries the air through internal ducts to be released downwardly outside road wheels. This is an example of an invention requiring some modifi- cation to the vehicle structure. GB 2172256 Kirkwood simply shapes the mudguard interior by means of an add-on angled deflector plate so that air tends to be diverted sideways from the tyre and under the vehicle rather than to the outside. This is followed by flow diversion using an aerofoil fin under the trailing part of the vehicle. Schmidt US 5299831 and Chassaing (EP 0576761) both have intakes low in front of the vehicle. Schmidt takes the duct flow along a Venturi-equipped tube built under the vehicle, having an inlet beside each wheel to be treated, while Chassaing diverts air at the inner aspect of each wheel, then diverts it into a duct from the trailing aspect of each wheel, using a system of large-area ducting. Both discharge the spray- laden air to the rear. Although Slivinsky et al (SU1525068) appear to collect air from the "Flettner area" (see later in this specification) in fact air is collected from all around the inside of the mudguard through holes into a chamber. Finally, Fitzhugh (US5324099) bolts an air turbine onto each wheel and these divert the spray radially from each wheel rather than out to the side of the vehicle.

OBJECT

It is an object of this invention to provide means for redirecting and controlling spray and/or dust raised by tyres on moving vehicles minimising the effect of the spray and/or dust, or at least to provide the public with a useful choice. STATEMENT OF INVENTION

In a first broad aspect the invention provides means for redirecting tyre spray likely to be projected sideways and outward from a moving road vehicle (if used under wet or dusty condi- tions), whereupon the projected spray may present a road hazard, wherein the means comprises a modified mudguard mounted in a position surrounding an upper part of at least one tyre; the mudguard having a leading end directed towards the usual direction of motion of the road vehicle; the mudguard having a trailing end; the mudguard including means to accept air (which may under wet conditions carry suspended water or under dusty conditions may carry suspended dust) from a "zone of collision" situated, when in motion, at an approximately defined region about the at least one tyre and means to divert the accepted air sideways and inwardly to an exit portal underneath the vehicle so that the redirected tyre spray does not present a road hazard.

Preferably the means to accept air is located in a position in the range of from about zero degrees to about 90 degrees towards the leading end of the mudguard, where zero degrees is vertically above the axis of rotation.

More preferably the means to accept air is located in a position in the range of from about 15 degrees to about 45 degrees towards the leading end of the mudguard.

In a first related aspect, the means to divert the air laterally inward comprises a duct mounted in relation to the leading end of the mudguard and having an exit portal facing toward the median line of the vehicle.

In a second related aspect the invention includes air entrapment means located on or near the trailing end of the mudguard; the air entrapment means comprising a flap made of a resilient sheet material partially enclosing a space behind the tyre. In a third related aspect the mudguard of the invention includes both an inner surface and an outer surface separated by a space; the duct is constructed within the space towards the leading end of the mudguard and the duct is provided with an exit portal facing toward the median line of the vehicle.

Preferably the exit portal is placed on or near the inner leading end of the mudguard. Preferably the exit portal faces toward the rear of the vehicle.

Preferably the exit portal includes passive means for aiding in the extraction of air from within the duct when the road vehicle is in motion. Optionally the passive means for aiding in the extraction of air from within the duct when the road vehicle is in motion includes a system of ducts that carry a flow of air and utilise the 90 Venturi effect.

Alternatively, the exit portal is provided with active means for supplementing the extraction of air from within the duct.

In a fourth related aspect the mudguard also includes a barrier between the inner aspect of the adjacent tyres and the median aspect of the vehicle.

95 In a second broad aspect, the invention is sold as an accessory mudguard for installation upon an existing vehicle.

In a third broad aspect, the invention is sold as part of a vehicle including means for redirecting tyre spray, wherein the vehicle includes at least one modified mudguard having passive air diversion means which utilises the air collision effect known as the Flettner or Magnus 100 entrainment effect in order to assist spray-laden air to pass along a diverting duct so that the amount of tyre spray likely to be projected sideways and outward from a moving road vehicle if used under wet conditions is reduced.

Preferably the weight-bearing tyres are fitted with the modified mudguards.

More preferably all the steering tyres are also fitted with the modified mudguards.

105 PREFERRED EMBODIMENT

The description of the invention to be provided herein (including preferred dimensions) is given purely by way of example and is not to be taken in any way as limiting the scope or extent of the invention.

It should be noted that where an explanation of an observed effect is given; that this expla- 110 nation is offered in good faith but should a different explanation later be proven to underly the workings of this invention, then existence of that different explanation shall not invalidate any rights attached to this invention or to this specification. We believe it is appropriate to identify the cause of the air movement patterns as the "Flettner Effect" after Anton Flettner (1885- 1961), although it may in fact be the "Magnus Effect"; relating to air flow and in particular to 115 an entrainment effect observed about a rotating cylinder intersecting a linear stream of air. See for example http://www.grc.nasa.gov/WWW/K-12/airplane/cyl.html for a Java simulation (accessed on 2 March 2004). In the special case of this invention, however, the rotating cylinder is in contact with a surface and the air may initially be stationary with respect to that surface (the road).

120 DRAWINGS

Fig 1: is a diagram showing directions of air currents (sometimes with spray or dust) about a tyre of a moving vehicle.

Fig 2: shows prior-art undiverted spray lines (as seen from below a moving truck) and diverted spray lines, according to the invention.

125 Fig 3: shows an external view of a mudguard made according to the invention.

Fig 4: shows a lateral exterior view of a mudguard made according to the invention.

Fig 5: shows a perspective view of a prototype mudguard made according to the invention.

Fig 6: shows a second perspective view of the prototype mudguard.

Fig 7: is a front elevation view of a fan-assisted mudguard according to the invention.

130 This invention relates to a device (normally used as a set of devices) for redirecting spray or dust thrown into the air from tyres of moving vehicles on wet roads. Much of this spray emerges laterally from about the wheels of a truck (or other vehicle) and comprises a significant, yet unnecessary road hazard. (For the purpose of this document, we regard dust thrown up from dry, non-sealed roads as behaving in a similar manner to suspended droplets

135 of water. Both are suspended in moving air).

Fig 1 diagrammatically indicates the fluid dynamics which the inventor believes is applicable to a wheel assembly 100, in contact with a road 103, of a vehicle moving from left to right. The invention makes use of the "zone of air collision" adjacent to a rotating and forward-moving tyre 101 (especially when in part confined beneath a mud guard 102 with optional flap 102A) as 140 a preferred region from which to collect the water-laden air into a water disposal means. Existence of the "zone of collision" (which has been observed) gives an opportunity to divert spray and/or dust. In order to render the "zone of air collision" a viable phenomenon, several mechanisms are believed to operate.

1. Air in front of the tyre (104) becomes a pressurised wedge of air 105 ( and '+') immediately 145 in front of the advancing tyre, and in particular close to the road 103, as the air becomes displaced. This air is subject to a raised pressure within an area which we call a "Flettner wedge" which reaches upward as well as outward, and makes the air 104 move upward in front of the tyre. Some of this will flow under the mudguard 102.

2. A corresponding wedge of air 106 behind the tyre is subjected to a reduced pressure ('-') as 150 a result of the departure of the tyre from the road at that point. Here, some spray is drawn off the road surface 103 and is later flung out from the grooves that comprise the tyre treads (103-Fig 3). The trailing flap 102A shown here is believed to assist in the action of the invention by retaining the spray developed in this zone for entrainment.

3. There is an entrainment effect 107 wherein air (and any spray present) is dragged away from 155 zone 106 in the direction of rotation of the tyre surface (particularly if a shroud or mudguard is present); this entrainment is believed to be due to a viscous effect of air and is believed to be related to the Flettner / Magnus effect.

As a result of meeting of the two air movements at or about 108, close observation by the inventor of rotating truck tyres in wet conditions has revealed a zone of interaction at a

160 position 108 around the tyre where the air is relatively stilled by collision between the two streams, and from where a substantial amount of the spray emerges. (At this time the inventor has not carried out experiments such as placing a radial array of pressure transducers about the interior of a truck mudguard in order to quantify the effect). This spray is "contaminated air" and this invention provides some example ways for handling this air so that less of the spray

165 (or dust) will emerge at about windscreen height of following passenger vehicles. The radial position of the zone of interaction would depend on a number of variables such as wheel size, tyre surface, tyre number, speed of movement, "contaminated air" density, and the relative geometry of the space between the tyre 101 and the mudguard 102. Generally though the position has been noted to lie in the region of 108 - at about the "12 o'clock to 2-o'clock

170 position"; that is, about from 0 degrees to 60 degrees from the top, in the direction of rotation around the circumference of the tyre, as seen from beside the vehicle. More generally the position of a catchment aperture intended to interact with the zone of interaction/collision 108 should lie in the range of from about zero to 90 degrees. This type of air flow behaviour is seen at higher road speeds, not at very low speeds.

175 Accordingly it would appear that provision of means for withdrawal of the air into a separating duct from about this region 108 (where withdrawal would presumably be easiest), would allow some at least of the spray to be removed, passively, from the environment adjacent to the rotating wheel assembly and from beside the vehicle (truck). A further complication is that for many road vehicles air moving towards the rear of the moving vehicle and underneath the

180 vehicle comes into collision with the differential and rear axle assembly and as a result of the raised pressure developed therein is diverted outwardly as shown by arrows 208, 209 in Fig 2. In wet conditions this air assists in carrying spray-loaded air from the tyres laterally out from the vehicle. (Sheet 602 in Figs 4,5, and 6 blocks at least some of that air flow).

Fig 2 shows two truck chassis, as seen from underneath, when in motion (direction indicated 185 by arrow 203). Tyres 205 (steering) and 206, 206A (dual sets for drive and weight bearing) are shown. The prior-art version truck 201 on the left indicates that air 204 flowing beneath the truck will tend to emerge at or about the wheels (207, 208, 209), carrying spray-loaded air laterally and towards the rear, outside the confines of the truck chassis. Much of this is delivered at about windscreen height for a following car 210. As a result, the car driver is

190 unable to see past the truck and efforts by the car driver to pass the truck are likely to result in collision. Further, the truck driver is less able to see in his rear-vision mirror an overtaking car through the spray and hence cannot take avoiding action if a collision appears imminent. On the right side of Fig 2 a truck chassis 202 fitted with the invention illustrates the concept of "spray diversion". Here, means (described later) to deflect spray-laden air, flowing from about

195 the tyres as shown by arrows 211, 213, and 214 results in a spray- (or dust-) laden stream emerging centrally from the rear of the truck at 215. Arrows 212 indicates air flow between front and rear wheels. It is considered that this type of diversion satisfies the immediate need of a driver of a following car 210A because the view past the side of the truck is made more clear and so a passing action is safer. (If the driver is close to and directly behind the truck,

200 spray will of course hit the car). Also, the truck driver of truck 202 has a better view in a rear- view mirror of following vehicles of low height, likely to engage in a passing manoeuvre. While it might be thought desirable to collect the water or dust on-board and dispose of it from time to time so that the truck collects rather than diverts the spray, truck drivers and fleet operators are not inclined to adopt anything that has a high capital cost, raises the cost of fuel,

205 and/or detracts from the payload.

EXAMPLE 1

Fig 3 shows a diagrammatic view 300 from the rear of a modified mudguard according to the invention. Preferably this mudguard is made of a plastics material or alloy, and may be made at low cost by use of a rotational moulding process. The device itself may be made of any

210 suitable material; a hard though not brittle plastics material perhaps including a proportion of recycled rubber as particles or as a blend at the molecular level may be used. This would be relatively insult-resistant. Alternatively, stainless steel, other metal sheets, fibreglass, alloys, or other suitable materials may be used. The preferred mudflap located at the trailing edge of each mudguard may be made of usual materials: rubber or toughened rubbery (resilient)

215 materials.

Preferably the mudguard includes an outer skin and an inner skin, made separately and then bolted or otherwise fixed together with internal ribs to maintain separation. This view shows the outer skin 301, the position of an internal guide 304 leading a flow of air 305 from the catchment inlet 303 to the rear-facing outlet 302, and a strip bearing holes for the preferred use

220 of a trailing, sloping mudflap (such as 102A) which helps retain spray-laden air for entrainment. Preferably the areal dimensions of the internal duct 307 leading to the exit 302 are always greater than the areal dimensions at the catchment inlet, and preferably the areal dimensions of the exit 302 are also greater than the areal dimensions at the inlet, so that preferred minimal obstruction to the flow of air through the duct is imposed. (The inventor notes that other prior-

225 art spray reduction schemes such as bristles inside the mudguard tend to obstruct the aerodynamic effects relied on here). Optionally, aerodynamic flares may be placed about the outlet so that some negative pressure (for assisting in the flow 305 of air) is developed when in use, such as by a Venturi effect. Example dimensions are provided although the skilled reader must understand that they are not limiting to the invention. Dimension A is 500 mm; although the

230 wider tyres used in dual sets on trucks nowadays often prescribe 630-650 mm. "Super-wide single" tyres are also being adopted. Dimension B is typically 75 mm and also represents the spacing between an outer skin and an inner skin. Dimension C is typically 625 mm, depending on the tyre diameter. The aperture 302 is typically 75 mm (D) x 500 mm (E) and the outer width of the outlet is 100 mm.

235 Mounting means are not shown here, because they depend principally on the type of vehicle to which the mudguard is to be fitted. The mudguard is preferably fitted to an axle by means of a clamp surrounding the axle, so that the mudguard moves with the tyres rather than being mounted on a chassis. That provides for closer control of the tyre: mudguard spacing, which is helpful to the invention. It also allows the trailing flap 102A to be located closer to the ground.

240 One preferred tyre: mudguard spacing is about 75 mm although this is given only by way of example. A need to put on and later take off chains for snow or ice conditions should of course be considered. Mounting means should of course have the reliability and strength required of any installation used about vehicle wheels, as will be apparent to one skilled in the relevant arts. Due care must be taken when fitting the invention into older trucks, in relation to

245 clearance from fitting such as leaf springs because the springs may be placed closer to the inner aspect of the wheels than is usual for a more modem airbag suspension.

Fig 4 shows the example mudguard 400 from the outside in elevation view (with the position of the tyre 401 indicated by a dashed line). 301 is the outer skin, 402 is the inner skin and 403 is one of the internal stiffening ribs that makes contact between the inner and the outer skin. 250 406 is the exposed edge that is visible from the outside. Note that the overall exterior view is of an unadorned, moderately thick semicircular shape of mudguard having an aperture a little larger than that of the tyre 401 within (which assists a driver if any of the tyres have to be changed). 404 is an edge of an inner shield which (a) adds to the strength of the invention, (b) 250 supports the invention and the exit duct, and (c) obstructs air tending to rash outward to the sides of the vehicle and over the tyres, after colliding with the differential and rear axle assembly. The dual-skin construction which is convenient for low-cost manufacture also provides one level of protection should a tyre tread come off and shred the inner layer of the mudguard. The catchment aperture is indicated at 303. This is situated at or about the position

255 where the air masses collide (see above). An outline of the duct is shown as a dotted line. The trailing mudflap is attached at 306.

EXAMPLE 2

Fig 5 is a perspective view 500 of a prototype dual-tyre right-side mudguard made in sheet metal (1.6 mm steel sheet, welded then painted). The front of the intended vehicle is indicated

260 by arrow 504. The catchment aperture 303 is shown within the upper part of the mudguard, which includes stiffening fins 501 and 502. The diverting duct 503 is visible externally because the preferred dual-skin design was not used in this prototype. 301 indicates a single skin. Dual skins are not essential to the operation of the invention. The inner wall 04 is shown with a cut-out at 405 to fit over the axle. Again, mounting details are not shown because they vary

265 with the vehicle. This drawing does not show the trailing mudflap.

Fig 6 is a view from the opposite aspect of the prototype dual-tyre right-side mudguard, again showing the inner wall; the obverse side labelled 404 with cut-out 405. 305 is an arrow indicating the path of exiting air or air including suspended spray or dust, emerging from the outlet (located within dashed ellipse 302) of the diverting duct 503. In this example the outlet 270 from the duct does not face the rear; it faces towards the median line of the vehicle.

VARIATIONS

Fig 7 is a front elevation view of a generic mudguard according the the invention, in place around dual tyres 101 on roadway 103. Although the inventor's preference is to use solely those higher pressures developed at or about the zone of collision as a result of vehicle and wheel

275 movement, without requiring any active suction devices for "pulling" the contaminant-laden air into the separation/transfer means, it may be found for example that a particular set of wheels on the driver's side of the truck will require more diversionary air flow than other wheels, and the option of a fan or other form of assisted air removal is needed in order to meet a standard that may be imposed in the future. In case air flow carrying suspended material requires further

280 assistance, a fan 701 may be mounted in a convenient position such as at the exit 302 of the duct 304. The fan might be electrically driven or driven from the rotating wheels themselves. Another form of assisted yet passive removal is attainable by use of a Venturi type of junction between the mudguard duct and another duct carrying air from a front air intake.

The duct may preferably have its exit portal brought backward and located behind the rear axle 285 so that it is not emitting air in the face of a relative pressure built up under the vehicle by collision with the axle and differential.

Possibly, de-icing wires powered from the truck electricity may be needed in adverse conditions in order to minimise blocking up of the duct. The risk of icing means that the duct cross- section should gradually increase towards the outlet.

290 While the inventor's preference is for mudguards to be "un-spring" that is, mounted on the axle so that they are controllably close to the tyre surfaces without colliding, there may be situations where the mudguards have to mounted from the sprang or otherwise suspended chassis. In that case the separation between the tyre surface and the inner aspect of the mudguard is greater, because of movement of the suspension, and efficiency may be lowered.

295 Rubber or other forms of resilient mounting brackets may be preferred.

An appropriately modified device according to the principles of the invention as herein described may be used on the (usually single-tyre) steering tyres if it is considered that these justify inclusion in a spray-reduction programme. Now that many trucks have at least 4 sets of steerable wheels, this alternative is likely to be more useful. Normally, the modified mounting

300 requirements provide for the device to turn with the direction of the steered tyres when the driver needs to turn a comer. On the other hand because nearly all spray is developed while the vehicle is travelling in a straight line, an alternative modification for use with steering wheels would simply locate the collection areas in relation to the straight-ahead positions of the steering tyres.

305 The improved mudguard for diversion of spray may be provided as an accessory for fitting to existing trucks, or it may be included at the factory as an integral part of a vehicle body which option is more likely to be appropriate for vans, buses and cars. The "accessory" option allows for easier replacement in the event of damage.

COMMERCIAL BENEFITS or ADVANTAGES

310 Use of this invention for redirection of spray from around a moving vehicle has significant road safety advantages (through improving visibility for all drivers involved) and should reduce the cost of road accidents for any country especially where long-distance trucks use the same roads as do cars, and where wet weather is prevalent. The road safety advantages include reduction in human suffering, hospital costs, staff replacement, disruption at places of employment, 315 insurance premiums, and in many other ways.

The principal application is on bulk haulage/long distance trucks and buses and the like although the invention may be applied to any road vehicles including cars, vans, buses, coaches, recreational vehicles or the like.

An advantage of the invention is that it is unobtrusive and does not detract from the styling or 320 design of a vehicle.

The spray redirection invention can operate passively, that is, without energy input. One advantage of that aspect is that it can also be used on a trailer which has minimal or no wiring.

The invention may be integrated with other means to lower the drag and other forms of air resistance on a long-distance vehicle so that fuel efficiency is raised. It is possible that even this 325 spray redirecter alone can reduce the air pressure acting on a large vehicle's wheels.

Improved removal of spray from about the tyres results in better grip under wet conditions, such as by following tyres.

Vehicles will not get dirty so quickly, resulting in a reduced cleaning bill.

Dust and spray is not so likely to drift from a road on to neighbouring properties.

330 Finally, it will be understood that the scope of this invention as described and/or illustrated herein is not limited to the specified embodiments. Those of skill will appreciate that various modifications, additions, known equivalents, and substitutions are possible without departing from the scope and spirit of the invention as set forth in the following claims.

Claims

I Claim:

335 1. Means for redirecting tyre spray likely to be projected sideways and outward from a moving road vehicle if used under wet or dusty conditions, whereupon the projected spray may present a road hazard, characterised in that the means comprises a modified mudguard mounted in a position surrounding an upper part of at least one tyre; the mudguard having a leading end directed towards the usual direction of motion

340 of the road vehicle; the mudguard having a trailing end; the mudguard including means to accept air (which may under wet conditions carry suspended water or under dusty conditions may carry suspended dust) from a "zone of collision" situated, when in motion, at an approximately defined region about the at least one tyre and means to divert the accepted air sideways and inwardly to an exit portal underneath the vehicle

345 so that the redirected tyre spray does not present a road hazard.

2. Means as claimed in claim 1 characterised in that the means to accept air is located in a position in the range of from about zero degrees to about 90 degrees towards the leading end of the mudguard, where zero degrees is vertically above the axis of rotation.

350 3. Means as claimed in claim 2 characterised in that the means to accept air is located in a position in the range of from about 15 degrees to about 45 degrees towards the leading end of the mudguard.

4. Means as claimed in claim 2, characterised in that the means to divert the air laterally inward comprises a duel mounted in relation to the leading end of the mudguard and

355 having an exit portal facing toward the median line of the vehicle.

5. Means as claimed in claim 2, characterised in that the means includes air entrapment means located on or near the trailing end of the mudguard; the air entrapment means comprising a flap partially enclosing a space behind the tyre.

6. Means as claimed in claim 4, characterised in that the mudguard includes both an 360 inner surface and an outer surface separated by a space; the duct is constructed within the space towards the leading end of the mudguard and the duct is provided with an exit portal facing toward the median line of the vehicle.

7. Means as claimed in claim 4, characterised in that the duct has an exit portal placed on or near the inner leading end of the mudguard and facing toward the rear of the

365 vehicle.

8. Means as claimed in claim 4, characterised in that the duct has an exit portal placed on or near the inner leading end of the mudguard and including passive means for aiding in the extraction of air from within the duct when the road vehicle is in motion.

9. Means as claimed in claim 8, characterised in that the passive means for aiding in the 370 extraction of air from within the duct when the road vehicle is in motion includes a system of ducts utilising the Venturi effect.

10. Means as claimed in claim 7, characterised in that the exit portal is provided with active means for supplementing the extraction of air from within the duct.

1 1. Means as claimed in claim 7, characterised in that the mudguard also includes a 375 barrier between the inner aspect of the adjacent tyres and the median aspect of the vehicle.

12. Means for redirecting tyre spray as claimed in any previous claim, characterised in that the means is provided as an accessory mudguard for installation upon an existing vehicle.

380 13. A vehicle including means for redirecting tyre spray, characterised in that the vehicle includes at least one modified mudguard having passive air diversion means which utilises the air collision effect known as the Flettner or Magnus entrainment effect in order to assist spray-laden air to pass along a diverting duct so that the amount of tyre spray likely to be projected sideways and outward from a moving road vehicle if used

385 under wet conditions is reduced.

14. A vehicle as claimed in claim 13 characierised in thai all the weight-bearing tyres are fitted with the modified mudguards.

15. A vehicle as claimed in claim 13 characterised in that all the steering tyres are fitted with the modified mudguards.