The invention relates to a lighting device having a wind-powered cleaning member.

Background of the invention

Such devices are known from WO 03/004777 in the name of the applicant. In the known device a road-side reflector post is provided with a wind vane which stores wind energy in a spiral torsion spring. After the torsion spring has been wound up to a predetermined level via air displacement generated by passing cars on the road along which the reflector posts are situated, and via natural wind, the spring tension is released and a cleaning brush is driven to sweep across the reflector surface. The blade of the wind vane is vertically directed and the rotation is transferred to a cleaning device via a set of gears. Even though the known device is effective in automatic cleaning of road side reflectors and hence saves many man hours cleaning the reflector posts by hand and also contributes to traffic safety by maintaining a clean reflector surface, the known device is relative complex an carries a large number of parts.

Furthermore, the known device cannot be easily retrofitted on existing supports such as light reflecting road posts.

It is also known that on busy roads with dense traffic or at windy loations, the wind vanes may be subject to many rotations, for instance as many as over 40 million in a year. This causes considerable wear and requires intensive maintenance of the lighting devices and frequent replacement.

It is therefore an object of the present invention to provide a lighting device, for instance for use as a road side reflector post, which has a wind-powered cleaning member that is of a relatively simple construction. It is another object to provide a lighting device which effectively transfers wind energy to mechanical motion of the cleaning member. The lighting device should furthermore be easy to retrofit onto existing light-active devices. It is a further object to provide a lighting device which requires relatively little maintenance and which can effectively clean the light-active surface in a wind powered manner. Summary of the invention

Hereto a lighting device according to the invention has a ring-shaped housing defining a side surface having therein a number of air outflow openings, and transversely to the side surface a substantially open air entry surface, an array of wind vanes rotatable around an axis that is mounted in the housing, along a circular trajectory in the housing and a light active surface situated in a central area within the circular trajectory of the wind vanes, substantially parallel to the air entry surface, a cleaning device or the light active surface being attached to the wind vanes for causing relative movement of the cleaning device along the light-active surface.

The lighting device of the present invention is of a simple construction requiring a relatively small number of parts. The ring-shaped housing forms a compact unit mounting the wind vanes within a relatively small volume. The housing according to the present invention can be placed onto a closed support surface while the wind can enter and pass to the wind vanes via the air entry surface and leave the housing via the openings in the side surface. In this way it is relatively easy to mount the lighting device, such as for instance reflecting road posts, either as a pre-assembled construction in the factory or by retrofitting existing road posts out in the field with a device of the present invention, without having to provide holes in such road posts for the wind to pass through.

The lighting device in which the present invention is embodied can be any outdoor light source which is subject to contamination, such as for example lights on buoys, indicating lights along air strips, lamp posts along streets, or road side posts.

Furthermore, the light-active surface can be reflective, retro -reflective or can be an actively illuminated surface such as by comprising an array of lamps or LED's. The light-active surface may be circular, elongated, triangular or may have any desired shape. In one embodiment, the lighting device is mounted on a cap which is provided with attachment members for fitting over a light reflecting road post. The cap may for instance have a shape corresponding to the top of existing road side posts, and is pressed over the top of such posts to cover the device's reflector. On the inside of the cap, clamping fingers or teeth of a ratchet may fitted that snap into place on the existing lighting device to maintain the cap in a non-removable position.

In order to limit the number of rotations of the wind vanes, and hence prevent excessive wear, a brake member is attached to the wind vanes. The brake member may comprise a friction device acting on the wind vanes, an electromagnetic brake member or any other suitable means for limiting the number of rotations of the wind vanes.

In one embodiment, the brake member comprises a torsion spring that is attached on one side to the wind vanes and on the other side to a part of the cleaning device that is stationary relative to the wind vanes. Upon rotation of the wind vanes driving the cleaning member, the resistance on the wind vanes exerted by the torsion spring increases until rotation comes to a stop. When the force exerted by the air stream on the wind vanes drops away, the spring unwinds and the wind vanes and connected cleaning member or light active surface are rotated back to their starting position. As the spring force acting on the wind vanes sets a lower threshold level, rotation is only allowed from a specific wind force onwards. The stiffness of the spring can be tailored to best suit prevailing wind conditions.

In one embodiment, the cleaning device may comprise a brush member extending diametrically across the surface of the light active surface. In this way, one rotation of the wind vanes provides two cleaning sweeps of the cleaning member along the light- active surface removing dust, dirt and soot.

Alternatively, the cleaning device comprises on or more brush members being with a fixed end attached to the wind vanes and extending along the light active surface from the wind vanes toward the axis to a free side. Brush members of this type are described in detail in WO2008/002133 in the name of the applicant. The slight pressure exerted by the brush members of this type in combination with their high frequency of movement provide an effective cleaning effect, without the need for rotationg parts.

Brief description of the drawings

Some embodiments of a reflector device in accordance with the present invention will, by way of example, be described in detail with reference to the accompany drawings.

In the drawings:

Fig. 1 shows a perspective view of a road-side post having a lighting device according to the invention,

Fig. 2 shows a detail on an enlarged scale of the lighting device according to fig. 1, Fig. 3 shows an exploded view of the components from which the lighting device of fig. 1 is assembled,

Fig. 4 shows a cap for retrofitting existing road side posts with a lighting device according to fig. 1, and

Fig. 5 schematically shows an alternative embodiment of a brush member for application in a lighting device according to the invention.

Detailed description of the invention

Fig. 1 shows a lighting device 1 according to the invention, in particular a reflecting device on a road side post 2. The lighting device 1 comprises a ring-shaped housing 3 in which a stub 19 (see fig. 3) is mounted, forming a central, substantially horizontal axis of rotation 4. In the housing 3, a circular set of wind vanes 5 is mounted rotatable around the axis 4 along a circular trajectory. In the central area 7 within the wind vanes 5, a light active surface or reflector 6 is placed. The reflector 6 is attached to the wind vanes 5 so as to be rotatable together with the wind vanes 5. A fixed cleaning device or brush 8 extends diametrically across the reflector surface. It is of course possible to mount the reflector 6 in a stationary manner and to attach the brush to the windvanes 5 such that the brush 8 is rotated over the stationary refiector surface. As can be clearly seen from fig. 2, wind entering the housing 3 via the air entry surface 11 -that is substantially parallel to the light-active surface of the reflector 6- at the front of the housing 3 in te direction of arrow W; can leave the housing via openings 9 in sidewall 10 in the direction of arrow W ₀ . When the wind vanes 5 rotate around the axis 4 driven by the wind, reflector 6 is rotated such that the brush 8 moves across the surface of the reflector 6 for removal of dirt particles, dust soot and other soiling that reduces the light reflecting properties of the reflector 6.

In fig. 3 the different components of the lighting device 1 are shown in an exploded view. The device comprises a cap 15 which is formed of two plastic members 16,

17. The housing 3 has a support strip 18 extending diametrically across a lower edge of the ring-shaped sidewall 10 of the housing. The strip 18 comprises a stub 19 carrying the wind vanes 5 such that they can rotate along the circular trajectory around the rotational axis 4. The wind vanes 5 rotate around stub 19 when driven by air displacement or wind caused by traffic passing along the road side post 2. The reflector 6 is constructed of a metal, backing 21 (such as aluminium) having glued thereon a reflective foil 20. This construction will cause, in view of the heat conducting properties of the metal, condensation of moisture on the foil 20 against the cool metal backing 21 which facilitates cleaning.

The reflector 6 is mounted in the central area 7 of the wind vanes 5. A spiral torsion spring 23 is connected with one of its ends to the wind vanes 5 and with its other end to the strip 18 of the housing 3. In stead of a spiral spring 23 it is possible to use a coil torsion spring, but in that case the dimensions of the housing in the direction of the axis 4 are likely to increase.

Figure 4 show that the lighting device 1 of the present invention is mounted on a cap 30 that can be placed on top of a reflective road side post 2, covering the existing reflector 31. As can be seen from fig. 5, at the inside of the cap 30, flexible latches 32, 33 are provided for forming a snap fit with a recess around the existing reflector 31 on the post 2 such that the cap can be placed without tools on the road side post 2 in a non- detachable manner. Fig. 5 shows an alternative cleaning device 8, of the type generally known from WO 2008/002133 in the name of the applicant. Four flexible brush members 37 are with a fixed end 36 attached to the housing 3 and have a free end situated near the central axis 4 of the reflector 6, that is rotatably attached to the wind vanes 5. The brush members 37 extend across the surface of the reflector and are flexible in order to be able to make a sweeping motion when the reflector surface 6 passes underneath these brush members.