FIELD OF THE INVENTION

[0001] The invention relates to a road stud used as a reflective marker on a road, and more particularly to reflective markers which are resiliently deflectable.

BACKGROUND OF THE INVENTION

[0002] Road studs are reflective markers which are often partially embedded in a road surface. Road studs provide proper delineation of road lanes, road shoulders, chevrons etc to all vehicular drivers. Road studs typically have one or more reflectors that reflect light from vehicles. Since roads studs are embedded in a road, often vehicles drive over them. Road studs are often designed to be resiliently compressible such that when run over by a vehicle tyre the road stud moves down to a compressed, down position and then returns to its previous up or resting position. These embedded road studs are usually supported via a compressible resilient device. It is important to keep the reflectors properly aligned with respect to the road to ensure proper retroreflection. However, repeated cycling of the road stud between the up position and the down position can result in wear of components and misalignment of the reflectors with respect to road leading to the loss and/or impairment of retroreflection. For example, EP 0043656 discloses a reflective road marker with a spherical rubber spring. The spherical shape allows for uneven wear of a reflector unit with respect to a casing during cyclic loading. Also, US 4,413,923 Wright discloses a self-cleaning reflective road marker with a rubber hemisphere. A cylindrical stud engages a top of the rubber hemisphere in response to passing of a tyre. Such a known design may introduce excessive loading on the rubber hemisphere due to single point contact between the stud and the hemisphere. Generally, known road studs have relatively large numbers of components making them relatively expensive to assemble and to deteriorate in use.

[0003] It would therefore be desirable to provide a road stud which is of simple construction and greater durability and which also resists misalignment which can lead to impairment of retroreflection. SUMMARY OF THE INVENTION

[0004] In accordance with a first aspect, a road stud comprises an outer body having a circumference about a main axis with alignment tabs extending from the circumference and a piston having a holder and a reflector, moveable between an up position and a down position so that a vehicle tyre passing over the marker depresses an elastomeric member compressibly supporting the piston. A base is coaxial with the outer body, wherein the elastomeric member is positioned on the base and the piston is at least partially positioned within the outer body. The base has a circumferential side wall defining alignment slots extending around the circumferential side wall, and the alignment tabs are insertable into the alignment slots upon rotation of the outer body about the main axis to one of only two locations with respect to the base.

[0005] From the foregoing disclosure and the following more detailed description of various embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology of road studs. Particularly significant in this regard is the potential the invention affords for providing a high quality, low cost road stud. Additional elements and advantages of various embodiments will be better understood in view of the detailed description provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings wherein:

[0007] Fig. 1 is an exploded isometric view of the road stud of Fig. 1 , showing a base, an elastomeric member, an outer body, a piston and a holder with reflectors.

[0008] Fig. 2 is a cross section view of a road stud in accordance with one embodiment.

[0009] Fig. 3 is a bottom side view of the elastomeric member of Fig. 2. [0010] Fig. 4 is a section view of the piston of Fig. 2 showing the elastomeric member of Fig 2.

[0011 ] Fig. 5 is a bottom side view of the piston of Fig. 2. [0012] Fig. 6 is a top side view of the outer body of Fig. 2. [00 3] Fig. 7 is a bottom side view of the base of Fig. 2.

[0014] Fig. 8 is a cross section view of a road stud in accordance with an alternative embodiment.

[0015] Fig. 9 is a bottom view of the elastomeric member of Fig. 8.

[0016] Fig. 10 is a section view of the piston of Fig. 8 showing the elastomeric member of Fig. 8.

[00 7] It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the road stud as disclosed here, including, for example, the specific dimensions of the elastomeric member, will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to help provide clear understanding. In particular, thin features may be thickened, for example, for clarity of illustration. All references to direction and position, unless otherwise indicated, refer to the orientation illustrated in the drawings.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0018] It will be apparent to those skilled in the art, that is, to those who have knowledge or experience in this area of technology, that many uses and design variations are possible for the road stud disclosed here. The following detailed discussion of various alternate features and embodiments will illustrate the general principles of the invention with reference to a road stud suitable for use as a reflective road marker. Other embodiments suitable for other applications will be apparent to those skilled in the art given the benefit of this disclosure.

[0019] Turning now to the drawings, Fig. 1 shows a road stud 10 in accordance with one embodiment having an outer body 30, a piston 20 having a holder 60 and a reflector 70, each face of the reflector 70 being adapted to reflect a different colour, an elongate elastomeric member 40, and a base 50. The base 50 is coaxial with the outer body 30 about main axis 80, and the piston 20 is at least partially positioned within the outer body 30. The holder 60 receives the reflector 70, and the piston 20 receives the holder 60. The base 50, outer body 30 and piston 20 may all be formed from engineering plastics. The elastomeric member 40 can be formed of a foam rubber or similar resiliently deformable material. A top surface 44 of the elastomeric member 40 is shown defining recesses 42 and a compression zone 45. The recesses 42 are adapted to receive underside flanges 21 of the piston 20, shown in Fig. 5 and discussed in greater detail below. The top surface 44 has a plurality of component surfaces positioned on either side of the compression zone 45 and on opposite sides of the recesses 42. Spacing out the component surfaces of the top surface 44 advantageously allows for enhanced load distribution of the piston 20 on the elastomeric member 40 during compression loading, helping to increase the useful life of the elastomeric member 40. A series of alignment tabs 31-34 (34 is shown in Fig. 6) of the outer body 30 operatively engage corresponding slots 51-54 of the base 50 when assembled together. As discussed in greater detail below, these tabs and slots allow for alignment of the outer body with respect to the base 50 in one of only two positions. A top surface of the piston 20 defines a plurality of horizontal slots 121-124. When the piston 20 is depressed by a vehicle wheel, air or possibly trapped rain water present between the piston and the elastomeric member is compressed and forced upward through the slots 121-124. This passage of fluid through the slots 121-124 advantageously helps to clean the surface of the reflectors 70.

[0020] Fig. 1 also shows that the piston 20 has a ledge 24, a plurality of projections 26- 29 and the outer body 30 have corresponding grooves 36-39. The projections 26-29 engage the grooves 36-39 and act to align the piston with respect to the outer body 30. Thus, when assembled together, the piston 20 is aligned with the outer body 30, and the outer body 30 is in turn, aligned with the base 50.

[0021] Fig. 2 is a cross section view of the road stud 10 shown with the piston 20 in the up position. The reflector 70 has been removed for ease of illustration. The elastomeric member 40 can be provided with a pair of feet 41 engaging a top 56 of the base 50. The elastomeric member 40 is sandwiched between the base 50 and the piston 20 and compressibly supports the piston 20. That is, the elastomeric member 40 biases the piston 20 toward the up position.

[0022] Typically the road stud 10 would be partially buried in a road such that at least part of the reflector 70 extends above the road. When a vehicle is driven over the road stud, the weight of the vehicle overcomes a biasing force of the elastomeric member 40, moving the piston 20 down along a main axis 80 towards the down position where the elastomeric member 40 is further compressed. After the vehicle has passed, the elastomeric member 40 uncompresses, urging the piston 20 back toward the up position. In the embodiment shown in the drawings the outer body 30 is generally cylindrical in shape, with a circumference about the main axis 80 and is provided with a circumferential, inwardly facing overhang 131. A ledge 24 of the piston 20 engages the overhang 131 at the up position, thereby preventing further upward motion of the piston 20 with respect to the outer body 30. Thus, the piston 20 fits within the base 50 and is limited to positions between the outer body 30 and the base 50 when moving from the up position to the down position.

[0023] Fig. 3 illustrates a bottom side view of the compressible elastomeric member 40. The elastomeric member 40 comprises the pair of feet 41 which extend to the top of the base 56. The pair of feet 41 is connected via a connector 43. The elastomeric member 40 further defines the compression zone 45 between the feet 41. When the piston 20 is moved from the up position towards the down position, the elastomeric member 40 is biased or squeezed into the compression zone 45. The depth of respective sides of the compression zone measured by the components X and Y in Figs 2 and 8 are not the same. In other embodiments they can be. Advantageously, the two pair of feet 41 of the elastomeric member 40 allow for even distribution of stress when the elastomeric member 40 is compressed. The two feet also help to ensure that movement of the piston 20 is essentially along the main axis 80. Limiting non-axial movement of the piston 20 helps to ensure that light reflected from the reflector 70 is directed towards its intended direction, and helps to increase the useful life of the road stud 10.

[0024] Figs. 4 and 5 show the piston 20 in greater detail. In accordance with a highly advantageous feature, the piston 20 is of unitary (that is, one piece) construction. This is advantageous over known road studs that are made up of multiple components, screws, fasteners, and the like, which need to be assembled together. Further, the holder 60 and reflector 70 may be insert moulded into piston 20, forming an easy to handle subassembly. The piston 20 is coaxial with the outer body 30 and has projections 26-29 that extend into corresponding grooves 36-39 of the outer body 30 (shown in Fig. 6) upon rotation of the piston 20 about the main axis 80 to one of only two circumferential positions with respect to the outer body 30 followed by subsequent sliding of the piston 20 projections 26-29 into the grooves 36-39.

[0025] This is accomplished by forming a pair of the projections 36, 38 at 180 degrees with respect to one another around the main axis 80, and a second pair of projections 37, 39 at 180 degrees with respect to one another, but with each of one pair of projections not being at 90 degrees with respect to each other but instead being circumferentially offset from each of the other pair of projections. In the embodiment shown in the Figs, an angle Θ of the offset is about 10 degrees, so the projections 26-29 of the pair of projections are 80 degrees and 100 degrees, respectively, from each other. The corresponding grooves 36-39 will be circumferentially offset in the same manner as the projections 26-29 so that they can be assembled together in one of only two circumferential positions.

[0026] Fig. 5 shows unitary flanges 21 extending downwardly from the piston 20. When assembled with the elastomeric member 40, these flanges 21 extend into the corresponding recesses 42 and serve to align the elastomeric member with respect to the piston 20. When the road stud piston 20 and the outer body 30 incorporate offset angles, to assist in their assembly, the exterior face of the outer body 30 and the base 50 are provided with a pair of opposed complementary projections 91 , 92 which are designed to overlie each other when the road stud is assembled. Such an arrangement should help eliminate the 50% chance of initially coupling the base 50 and outer body 30 together incorrectly.

[0027] Fig. 6 is a top side view of the cylindrical outer body 30. The outer body 30 has a circumference 35 about the main axis 80 and has alignment tabs 31-34, preferably unitary alignment tabs, extending radially away from the circumference 35. These alignment tabs 31-34 are asymmetrically positioned around the main axis in a manner similar to the projections 26-29 of the piston 20. The alignment tabs 31-34 extend into alignment slots 51-54 of a circumferential side wall 58 of the base 50 (best shown in Fig. 1 ) upon rotation of the outer body 30 about the main axis 80 to one of only two locations with respect to the base 50. This advantageously helps to ensure alignment of the outer body 30 with respect to the base 50. The alignment slots 51-54 may be L-shaped (as best shown in Fig. 1 ) so that after the outer body alignment tabs 31-34 are inserted, the outer body 30 may be rotated about the main axis 80 to move the tabs 31 -34 to a position which resists dislocation of the tabs 31-34 from their corresponding slots 51-54.

[0028] As shown in Fig. 6, the alignment tabs 31 -34 are circumferentially co-aligned with the grooves 36-39 with respect to the main axis 80. Since the piston 20 is aligned with the outer body 30, and the reflector 70 is rigidly attached to the piston 20, the effect is to align the reflector 70 with respect to the outer body 30 and the base 50 of the road stud 10. Thus when assembled, the projections 26-29 of the piston 20 are aligned with the corresponding grooves 36-39 of the outer body 30, the alignment tabs 31-34 of the outer body 30 engage the L-shaped slots 51 -54 of the base- 50, and the piston 20, outer body 30 and base 50 are co-aligned along the main axis 80. Thus, all elements of the road stud 10 are in positions that keep the reflectors 70 in line for proper reflection, i.e., the reflection of light from the reflectors 70 is visible to drivers on a road with such road studs 10.

[0029] The underside 57 of the base 50 is shown in Fig. 7 and is provided with a pair of alignment projections 55 that extend toward the earth or a part of the road. The alignment projections 55 help resist movement of the road stud 10 out of alignment after initial placement of the road stud 10 into the road and also serve the purpose of reinforcing ribs for the base 50. In alternative embodiments further alignment projections 55 orthogonal to or parallel to those already described may be present.

[0030] Fig. 8 shows in cross section, a road stud 10 in accordance with an alternative embodiment. In this embodiment, the road stud 10 incorporates a slightly different elastomeric member 40 (also shown in Figs 9 and 10) to the one described hereinabove. In this alternative embodiment, the underside of the elastomeric member 40 has been provided with a reinforcing member 90 of identical material to the rest of the elastomeric member 40. The reinforcing member 90 is of uniform thickness throughout its length, coaxial with the principle axis of the elastomeric member 40 (thus subdividing the lower part of the compression zone 45) and in this embodiment spans the entire plane (parallel with the principle axis of the elastomeric member) of the underside of the compression zone 45 continuously.

[0031] In addition, the top surface 44 and the bottom surface of the pair of feet 41 are curved so as to enable the respective top and bottom surface areas to progressively contact the piston 20 and the base 50 during movement of the piston 20 from the up position towards the down position. In the embodiment illustrated, both the top and bottom surfaces are convex but one could be convex and one could be concave or only one surface (top or bottom) could be curved, the other being flat. Furthermore, both top and bottom surfaces are only curved with respect to a plane orthogonal to the principle axis of the elastomeric member 40, in other embodiments of course, the nature of the curve could be such that it is present in both planes. In further alternative embodiments, only the top surface 44 or the bottom surface of the pair of feet 41 need be so shaped in this way.

[0032] It is to be appreciated that the invention is also include within its scope a road incorporating one or more road studs of the present invention.

[0033] From the foregoing disclosure and detailed description of certain embodiments, it will be apparent that various modifications, additions and other alternative embodiments are possible without departing from the true scope of the invention. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to use the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.