GB2229470A

GB2229470A - Reflective road stud

Info

Publication number: GB2229470A
Application number: GB8903870A
Authority: GB
Inventors: John Lloyd
Original assignee: Glasdon UK Ltd
Current assignee: Glasdon UK Ltd
Priority date: 1989-02-21
Filing date: 1989-02-21
Publication date: 1990-09-26
Anticipated expiration: 2009-02-21
Also published as: GB8903870D0; GB2229470B

Abstract

A reflective road stud comprises an open topped rectangular shell formed in a resilient material to locate in a road mounted socket, a transverse wall having banks (16) of reflective elements on either side thereof, the wall being mounted on resilient arms extending from both ends of the wall to opposing sides of the shell to support the wall extending across and projecting above the periphery of the shell whilst permitting the wall to be depressed into the shell and restoring the wall to the projecting position when released, the arms also resisting resiliently movement of the wall transverse to its lengthwise direction. Spaced wiper elements (21) are mounted in the shell to engage the reflective elements on either side of the wall when the wall is depressed into the shell, the wiper elements have resilient mountings (20) which bias the wiper elements against the defective elements whilst permitting the wiper elements to accommodate said transverse movement of the wall. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO REFLECTIVE ROAD STUDS This invention relates to reflective road studs for location in road mounted sockets for guilding night time vehicle traffic. One well known form of reflective road stud embodies two pairs of reflective lenses facing in opposite directions and is commonly known as the "cat's eye" reflectors. Such reflectors have been widely used for many years but do have a number of significant short coming which can be summarised as follows: 1. It uses only two large bi-convex lenses per reflective face and the reflective performance is low by modern international industry standards.

Because there are only two lenses per face, if either is chipped by flying stones etc., 50% of reflectivity is loas and this is not unusual.

2. The lenses are held in copper sleeves which in turn are mechaniscally anchored into the rubber housing by copper pins passing through inner extensions of the sleevers from the underside of the rubber moulding. It is quite common for this assembly to fail in service and for lenses to be lost long before the pad has come t the end of its normal working life.

3. The shell tends not only to depress under traffic action but also to be elastically distorted in the direction of the traversing vehicle. This rearward distortion with respect to vehicle motion has the effect of increasing the pressure between the reflector and the rear wiper blade which is itself restricted from rearward movement by the rear wall of the socket, causing accelerated wear of the blade and leading ultimately to ineffective wiping.

Conversely, at the side of the shell facing the traversing vehicle, pressure between the wiper blade and reflectors is reduced making the cleaning action less effective.

The present invention seeks to overcome the above disadvantages.

According to one aspect, the invention provides a reflective roadstud comprising an open topped rectangular shell to locate in a road mounted socket, a wall having banks of reflective elements on either side thereof, the wall extending across and projecting above the periphery of the shell, resilient for arms mounting the wall extending from both ends of the wall through either side of the shell to permit the wall to be depressed into the shell and to restore the wall to the projecting position when released whilst resisting resiliently movement of the wall transverse to its lengthwise direction and spaced wiper elements mounted in the shell to engage the reflective elements on either side of the wall when the wall is depressed into the shell, the wiper elements having resilient mountings which bias the wiper elements against the reflective elements whilst permitting the wiper elements to accommodate said transverse movement of the wall.

According to a further aspect, the invention provides a respective road stud comprising a rectangular shell to locate in a road mounted socket, a wall having banks of reflective elements on either side thereof extending across and projecting above the periphery of the shell and resiliently mounted on the shell to permit the wall to be depressed into the shell and to restore the wall to the projecting position when released and wiper elements mounted in the shell to engage the reflective elements on the wall when the latter is depressed into the shell, the wiper elements being mounted in recesses in the side walls of the shell to permit limited movement of the wiper elements with the reflective element carrying wall without engaging the socket when the wall is distorted towards one or other side of the shell by the wheel of a passing vehicle.

The following is a description of some specific embodiments of the invention, reference being made to the accompanying drawings in which: Figure 1 is a front elevation view of a first form of reflective road stud in accordance with the invention; Figure 2 is a plan viex of the reflective road stud shown in Figure 1; Figure 3 is a under plan view of the stud shown in Figure 1; Figure 4 is a side view of the stud shown in Figure 1; Figure 5 is a section on the line 5-5 on Figure 2; Figures 5A and 5B show parts of the construction of Figure 5 in two operative positions; Figure 6 is a section on the line 6-6 on Figure 4; Figure 7 is a section on the line 7-7 on Figure 4; Figure 8 is a section on the line 8-8 on Figure 4; Figure 9 is a scrap section on part of the wiper element of the stud;; Figure 10 is a front elevation of a second form of reflective stud; Figure 11 is a plan view of the second form of stud; Figure 12 is an under side view of the second form of stud; Figure 13 is a side elevation of the second form of stud; Figure 14 is a section along the line 14-14 on Figure 11; Figure 15 is a plan view of one wiper element of the stud of Figures 11 to 14; Figure 16 is a section on the line 16-16 on Figure 15; Figure 17 is a front view of the wiper element; Figure 18 is a under plan view of the wiper element; Figure 19 is a section on the line 19-19 on Figure 17; Figure 20 is a section on the line 20-20 on Figure 17; and Figure 21 illustrates a modification to the wiper element of Figures 16 to 20.

Referring firstly to the embodiment of the invention shown in Figures 1 to 9 therein shown a reflective road stud indicated generally at 10 for location in a road mounted socket which may be of cast iron, aluminium alloy or plastics material. The socket which is not illustrated has the generally rectangular cavity form therein with a horizontal base. the cavity provides parallel front and rear walls within which the reflective road stud is contained. The opposed parallel side walls of the cavity each has a pair of integral projecting fingers extending into the socket to engage in corresponding armatures formed in the side walls of the reflective road stud as described later.

The reflective road stud illustrated is formed in a synthetic rubber or plastics material comprising a open top shell having side wall 11 each formed with a pair of square shaped openings ila to receive the integral attachment fingers on the sides of the socket to locate the stud in the socket.

A centrally disposed top wall 13 extends across the socket between the side walls 11 projecting above the side and end walls and being connected to the side walls by downwardly inclined bridging members 14. The top wall 13 is formed on either side thereof with outwardly facing sockets 15 in which rigid plastics blocks 16 are secured by adhesive. Each block has an outwardly directed vertical face 17 in which an array (e.g. 23) of very small by-convex reflectors are mounted at closely spaced locations over the surface to provide a highly reflective surface when light from a vehicle is directed at the bank of reflectors.

Each end wall of the socket comprises a shallow base section 18 having a short dependent flange 19 at the outer periphery of the socket and an upstanding wall portion 20 recessed inwardly of the outer periphery of the socket and extending between the side walls thereof. The central region of the upper part of the wall portion 20 is formed with two or more parallel wiping lips 21 which lie closely adjacent the lower part of the block 16 in which the reflective elements 17 are set. In the normal orientation of the socket, the lips 21 engage a part of the block 16 below the reflective elements but when the central wall 30 is depressed by a vehicle wheel passing over the socket, the reflective elements 17 are swept across the lips 21 which thereby perform a cleaning action on the reflective elements.The action will now be described in greater detail with reference to Figures 5a and 5b.

There is a problem in maintaining a contact pressure between wiper and reflector over the prolonged period due to the tendency of any elastomer to relax and to take a set in a position where the pressure is reduced. This problem would be reduced by selecting a very low hardness grade of rubber but this would be unsuited to the other mechanical requirements of the pad. We have therefore developed a further feature designed to allow the wiper pressure in the shell's non-depressed form to be iether very small or zero but the generate increased pressure between the wiper and reflective instantaneously in response to the action of depressing the shell.

As shown in Figure SA the wiper 21 is situated at the top of end wall 20 which does not extend directly to the floor of the socket but joins on to base 18 which is spaced above the floor of the socket by a further dependent flange or protrusion 1A. The supporting wall 20 is attached at its outer ends to the depressible part of the shell in the general area E by a connection which, being integrally formed in the rubber of the shell is flexible. When the depressible part of the shell moves downwards, it exerts a downward pressure on wall 20 through the flexible connection at E. The end of the base 18, supported by flange 18, cannot move correspondingly but the unsupported end of the base 29 can move donwards and does so by pivoting about the flucrum of flange 18.This in turn biases the supporting flange 20 towards rotation about the same fulcrum point and, although some of this potential arcuate movement is absorbed by elastic deformation of the flanges and connection E, the overall result is that the lower part of wall 21 moves substnatially about fulcrum 18 whilst the upper part is rfestrained from such mvoement by contact between the wiper and the reflector (Figure 5B). Wall 20 is thus bowed and the force resulting from the eleastic resistance to this bowing provides a contact pressure between the wiper and reflector. The the depressible part of the shell is alloed to recover its original position, the attitude of the various flanges reverts to Figure 5A position on the reflector is relaxed.

Although the central wall carrying the reflectors has been reduced in width to space the reflectors and their wipers inwards from the socket walls, the side walls of the shell (containing the prong apertures) which support this central wall have their upper corners extended to abut the end faces of the socket. This abutment helps to reduce the rearward displacement of the central wall under vehicle impact.

Reference is now made to the second stud form shown in Figures 11 to 21.

The underlying concept of this design is the more effective bracing of the reflector carrying portion 30 of the shell 10 against rearward dislocation during depression. The principle is to support the reflector unit between two bridge members 31 which span the receiving socket in the direction parallel to the traffic flow. By making such bridge members relatively flat they can be depressed from ta convex arch to a concave attitude to facilitate depression of the reflectors held between them but since these bridges remain substnatially horizontal bars throughout, their outer ends remain firmly abutting opposed interior faces of the socket.

With the ends of the bridges so abutted, the reflector section can only move rearward by compressing longitudinally the bridge membes. This arrangement provides substantially greater resistance to rearward movement of the reflector (16, 17) than in the conventional arrangement where reflectors are mounted on either side face of a single broad bridge unit spanning the socket transversely. There is also an advantage in the twin bridge approach in that it enables the width and therefore the mass of the centre part of the moulding carrying the reflectors to be reduced and this makes the movement of the reflectors to be reduced and this makes the mvoement of the reflectors under tyre impact more controllable particularly with regard to over travel in the depressing action.

A further feature is the use of wipers 32 formed as separate mouldings and attached to the main shell. This has been done for three reasons.

Firstly, it enables the wipers to be moulded in a more flexible material thaqn the rest of the shell and this has an advantage when typing to maintain a constant light wiper pressure and the minimise wiper wear as it has less tendency to take a permanent set and has better abrasion resistance. Secondly, the separate moulding enables the wipers to be moulded in a form which when assembled creates a pre-load pressure between thewiper and the reflector when in the non-depressed position. This obviously cannot be achieved if wipers are moulded integrally. The third reason for moulding the wipers separately is purely to simplify mould construction as it would be extremely difficult to mould the design as a single unit.

The engagement on the prongs of the socket is affected by a bar 33 of material formed by the end wall 11 passing under the prongs and which may have vertical faces 34 at its ends and a vertical projection 35 in its centre to engage the side faces of the prongs but which is upwardly open. This feature has two advantages. Firstly, it creates an open area above the prongs into which the adjacent bridge member may depress and, secondly, it simplifies the mould construction in that the moulding and mould can be separated in a single direction. Where side apertures are formed in theskirt of the shell, a secondary sideways movement is necessary to separate the moulding from the mould.

Thus the reflective road stud socket constructions described by have the following features of significants in common: i) An array (e.g. 23) of very bi-convex reflectors per reflective face, these reflectors being partially capsulated in a moulded plastics carrier block which in turn is retained by adhesive in a recess in the rubber shell of the stud; ii) The wipers are spaced well away from the walls of the receiving socket to enable them to deflect through at least lcm in response to movement of the reflector carrying portion of the shell; ii) The wipers and their supporting walls are so designed that during large movements of reflectors on, the contact pressure between the wiper and reflector is light and fairly constant. This gives both effective wiping and extended wiper life and in both designs this has been achieved by mounting the wipers at the top edge of a substantially vertical wall extending downwards into the socket and so arranged that this wall can either flex or pivot from its base.

Claims

1. A reflective road stud comprising an open topped rectangular shell formed in a resilient material to locate in a road mounted socket, a transverse wall having banks of reflective elements on either side thereof, the wall being mounted on resilient arms extending from both ends of the wall to opposing sides of the shell to support the wall extending across and projecting above the periphery of the shell whilst permitting the wall to be depressed into the shell and restoring the wall to the projecting position when released, the arms also resisting resiliently movement of the wall transverse to its lengthwise direction, and spaced wiper elements mounted in the shell to engage the reflective elements on either side of the wall when the wall is depressed into the shell, the wiper elements have resilient mountings which bias the wiper elements against the deflective elements whilst permitting the wiper elements to accommodate said transverse movement of the wall.

2. A reflective road stud as claimed in Claim 1, wherein the shell comprises a pair of upstanding side walls interconnected by cross members extending between the opposed ends of the side walls, the transverse wall carrying said reflective elements extending between the side walls and being connected by said arms extending downwardly and outwardly from the ends of the transverse wall to the upper ends of the side walls.

3. A reflective road stud as claimed in Claim 2, wherein the wiper elements are mounted on respective inner partition walls extending between the side walls and extending upwardly from the cross members to support the wiper elements for engagement with the reflective elements when the transverse wall is depressed as aforesaid.

4. A reflective road stud as claimed in Claim 3, wherein said partition walls are inset from the ends of the side walls and the outer edges of the cross members.

5. A reflective road stud as claimed in Claim 3 or Claim 4, wherein the upper edge of each partition wall extends along the lower side of a respective bank of reflective elements and a plurality of wiper elements are formed integrally with the upper part of the partition wall on the side adjacent the bank of reflective elements extending generally parallel to the wall to engage in succession the bank of reflective elements when the transverse wall is depressed into the shell.

6. A reflective road stud as claimed in any of Claims 2 to 5, wherein the side walls of the shell are formed with spaced apertures to receive spaced projections on the sides of a road mounted socket to engage in and hold the shell in the socket.

7. A reflective road stud as claimed in any of Claims 2 to 6, wherein ribs are formed integrally with and extend along the undersides of said cross members at the outersides thereof whereby, when the transverse wall is depressed, the side walls and inner partition walls are also depressed into the socket and the cross-members are subjected to a twisting action which results in a fce on the partition walls biassing the wiper elements against the relfective elements.

8. A reflective road stud as claimed in any of Claims 2 to 7, wherein the resilient arms supporting the transverse wall on the side walls of the shell taper in thickness between the transverse wall and shell.

9. A reflective road stud as claimed in Claim 8, wherein a groove is formed in the upper surface of each resilient arm adjacent the transverse wall extending across the arm to facilitate the flexing of the arms with respect to the transverse wall as the wall is depressed into the shell.

10. A reflective road stud as claimed in Claim 1, wherein the shell comprises upstanding side and end walls and the transverse wall extends parallel to the end walls and has arms extending transversely from both ends thereof outwardly and downwardly to the end walls to form bridge formations supporting the transverse wall in the shell and to allow the transverse wall to be depressed into the shell.

11. A reflective road stud as claimed in Claim 10, wherein each side wall has a pair of upwardly open recesses spaced apart by a partition to receive pairs of projecting fingers in the sides of the road mounted socket to locate the shell in the socket.

12. A reflective road stud as claimed in Claim 10 or Claim 11, wherein resilient L section members are secured to the side walls of the shell, one limb of each L extending across the base of the shell towards the centre thereof and the other limb extending upwardly adjacent a respective side of the transverse wall and being formed with a plurality of wiper elements being formed along the side of said upstanding member adjacent the transverse wall parallel to the transverse wall to slide over the transverse wall as the latter is depressed into the shell, the upstanding members of each L passing between the arms supporting the wall as the wall is depressed.

13. A reflective road stud as claimed in any of the preceding claims, wherein each bank of reflective elements comprises a rigid block in which a multiplicity of closely spaced reflective beads is embedded.

14. A reflective road stud substantially as described with reference to and as illustrated in Figures 1 to 9 of the accompanying drawings.

15. A reflective road stud substantially as described with reference to and as illustrated in Figures 10 to 21 of the accompanying drawings.