This invention relates to the reduction of the thermal signatures of wheeled vehicles. The term “wheeled vehicle” as used herein includes a tracked vehicle because such vehicles have visible wheels around which the tracks run.
In military operations, a vehicle is vulnerable to detection at night or in other conditions of poor visibility by thermal imaging. The wheels are often prominent in a thermal image of a vehicle, because of heat generated by the vehicle's brakes, by heat generated in the vehicle's tyres by friction with the road or other surface over which it is travelling, and by the conversion into heat of energy absorbed by the tyre during flexure.
A vehicle also is made more vulnerable to detection due to dust thrown-up by its wheels or tracks when travelling over dusty surfaces for example as in deserts. The resulting dust cloud may be visible from a considerable distance and may also have a substantial radar signature.
The present invention can offer an integrated approach to the reduction of these problems.
According to the invention, there is provided apparatus for reducing the thermal signature of a wheel and adjacent parts of a vehicle, comprising a first thermal shield configured to be mounted outwardly from the wheel and extending over at least a substantial portion of the radial extent thereof, and a further thermal shield configured to be mounted from fixed structure of the vehicle outwardly of the first thermal shield, and to overlap at least part of said first thermal shield.
When the wheel is fitted with a tyre, the first thermal shield preferably also extends over a substantial portion of the radial extent of the tyre.
The apparatus preferably comprises mounting means for mounting the first thermal shield so as to be spaced apart from the wheel outwardly thereof.
The overlapping of the two thermal shields can reduce the thermal signature of any radially outer part of the wheel which is not covered by the first thermal shield. In non-tracked vehicles for example, the first thermal shield preferably is of rather smaller diameter than the tyre so that it does not permanently contact the ground during movement of the vehicle on a relatively smooth surface such as a road. It may intermittently contact the ground when the vehicle is passing over an irregular surface, and therefore the first thermal shield preferably is flexible to accommodate such contact.
The first thermal shield may comprise brush means.
The brush means may extend radially outwardly from a central portion of the shield which is configured for mounting from the vehicle wheel.
The brush means may comprise radially-extending bristles.
There may be a flexible support for the brush means extending over a radially inner portion thereof. The flexible support may be a disc e.g. of an elastomeric material configured to be disposed between the wheel and the brush means. Alternatively it may be configured to be disposed outwardly of the brush means relative to the wheel.
Preferably the further thermal shield is configured also to suppress dust thrown up by the vehicle.
The further thermal shield may be configured to be mounted from a wheel arch of the vehicle.
The further thermal shield may comprise brush means extending around a wheel arch of the vehicle and projecting towards an axis of rotation of the wheel.
Alternatively it may comprise a skirt configured to be mounted so as to extend downwardly over a substantial portion of the first thermal shield.
Preferably the first and further thermal shields are comprised of materials having the same or similar emissivity.
The first thermal shield, being mounted from the outer surface of the wheel, also can assist in dust suppression by capturing some of the dust thrown up at the lower part of the wheel and retaining it for a long enough period of time so that when it is released it is behind the further thermal shield and its escape is impeded.
The invention now will be described merely by way of example with reference to the accompanying drawings, wherein
Referring to
In an embodiment of the invention shown in
A brush disc comprising a compressed central portion 26 and radially—extending bristles 30 is retained on the carrier 22 by a retaining plate 32 e.g. of plastics, glass reinforced plastics or aluminium. The plate 32 is fixed to the carrier 22 by bolts (not shown) passing through bores 34 in the retaining plate 32 and the disc 28 to threaded holes 36 in the carrier 22. The bristles 30, may be partially backed with a thin disc of flexible rubber type material 29 (shown only in
The bristles 30 extend over the wheel 10 and the greater part of the radial extent of the sidewall 38 of its tyre 12. A radial clearance 40 is left so that in normal circumstances the ends of the bristles will not contact the ground 19. If however the vehicle is travelling over uneven ground, the ends of the bristles may come into contact with the ground due to increased flexure of the tyre and suspension travel. The bristles are of a suitably flexible material e.g. of nylon, polyamide or polypropylene so that they deflect when they contact the ground.
Preferably the carrier 22 is dimensioned so that the brush 28 is spaced outwardly from the wheel as illustrated. This assists in thermally insulating it from the wheel, and aids the entrainment of dust behind the brush as described hereinafter. It also permits the sidewalls of the tyre to flex outwardly without deforming the brush.
Around the outer periphery of the wheel arch 19 is another brush 42, made of the same material as the brush 28. The bristles of the brush 42 extend inwards towards and partially overlap the bristles 30 of the brush 28. The brush 42 thus thermally shields the outer part 40 of the tyre which is within the angular compass of the wheel arch 19 and which is not shielded by the brush 28. Indeed the brush 42 covers all of the interior of the wheel arch 19 which is not occupied by the wheel, and thus also shields any thermal signatures of the engine or other components of the vehicle which are visible around the wheels through the wheel arch 19.
As shown schematically in
The effectiveness of the thermal shield 28, 32, 42 of
The brushes 42 and shirts 50 must of course be positioned sufficiently outwardly of steered wheels of the vehicle to permit the wheels to be turned from lock-to-lock without the brushes 28 coming into contact with the brushes 42 or skirts 50.
The invention also includes any novel features or combination of features herein disclosed, whether or not specifically claimed. The abstract of the invention is repeated here as part of the disclosure
The thermal signature of a vehicle is reduced by providing a thermal shield for at least one of the vehicle's wheels covering at least a greater part of the wheel area, in combination with a further shield around or depending from the wheel arch and which overlaps the wheel-mounted shield. The shields may also co-operate to reduce the generation of a dust cloud by the vehicle.
Number | Date | Country | Kind |
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10250742.3 | Apr 2010 | EP | regional |
1005837.8 | Apr 2010 | GB | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/GB2011/050607 | 3/25/2011 | WO | 00 | 10/9/2012 |