Information
-
Patent Grant
-
6334734
-
Patent Number
6,334,734
-
Date Filed
Monday, August 30, 199924 years ago
-
Date Issued
Tuesday, January 1, 200222 years ago
-
Inventors
-
-
Examiners
- Will; Thomas B.
- Addie; Raymond
-
CPC
-
US Classifications
Field of Search
US
- 404 12
- 404 14
- 404 15
- 404 16
-
International Classifications
-
Abstract
A reflective pavement marker integrally molded in one piece structure having retroreflective face and structural body. The marker provide a mean to enhance agglutination to the roadway, if needed when bituminous based adhesive is used by maximizing the base area for adhesive wetting parameter. The reflective face and the structural body integrally made of high impact and abrasion resistance thermoplastic. Recessed reflective cells within the reflective face tend to minimize contact with tires and other abrasive roadway elements.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the retroreflective roadway markers that are used for traffic lane delineation and in particular, to markers with enhanced reflectivity and abrasion resistant.
2. Related Art
Roadway markers are adhered to pavements along centerlines, edge lines, lane dividers or guardrail delineators. Other roadway markers are used as temporary lane dividers in temporary constructions, detours or prior to permanent marking of newly paved roadways.
Since 1965, the most commonly used retroreflective roadway markers are based on Heenan U.S. Pat. No. 3,332,327 or Balint U.S. Pat. No. 3,409,344.
Typically, this type of markers are produced in a process consisting of four to five steps:
First, injection molding of a thermoplastic shell, either integrally molded with the reflective face, or the reflective faces welded on a corresponding open recesses within the shell. The reflective face, having 350 or more cube corner reflective elements on each reflective face of the shell.
Secondly, either the cube corner reflective elements within a shell or the entire inside surface of the shell coated with a reflective sealer by a process known as vacuum in metalizing. This metallic sealer needed to seal the cube comer reflective elements so they retain part of their retroreflectivness prior to the next step, of filling the shell with a thermosetting resinous material, such as epoxy or polyurethane. This resinous filler material encapsulate the metalized cube corner reflective elements and give the marker the structural body.
Finally, a layer of relatively course sand or glass beads dispersed over the top surface of the filler material (this top surface will be the marker's base) prior to solidification of the filler material. Part of the sand particles will remain partially protruding above this planar surface of the marker base, thereby increase the adhesive welding parameter of the base surface. This will improve adhesion to substrate, regardless of the type of adhesive used. This type of markers worked well for six or seven months, however, due to poor abrasion and impact resistant of the thermoplastic shell, nearly 60% of the reflectivity is lost thereafter. Also, incompatibility of the shell material to the resinous filler material, causes pealing of the reflective face or the shell, thereby losing retroreflectivity. Several attempt were made to improve abrasion resistant of the reflective face. One was the use of thin layer of untempered glass as disclosed in U.S. Pat. No. 4,340,319. Another attempt was the use of polymeric coating of the reflective face, as disclosed in U.S. Pat. No. 4,753,548 (Forrer). These abrasion resistant coating proving to be expensive and tend to reduce retroreflectivity.
Other major development in the pavement marker art have been made in the attempt to eliminate the use of the metalized sealer for the cube corner reflective elements. This has been achieved by dividing the inside surface of the reflective face into reflective cells, each cell will have several cube corner reflective elements, the cells isolated from each other by partition and load carrying walls. The entire reflective face welded to corresponding recesses within a hollowed body.
This method is disclosed in U.S. Pat. No. 4,227,772 (Heenan); U.S. Pat. Nos. 4,232,979; and 4,340,319 (Johnson et al); U.S. Pat. No. 4,498,733 (Flanagan). These markers proved to be superior in reflectivity, however, lack of structural strength and poor adhesion cause short life cycle for this type of markers.
This applicant successfully developed two multi-cell reflective roadway markers. One roadway marker utilizes raised rhombic shaped abrasion reducing and load transferring raised ridges which act to intercede abrasion elements and impact load, the shell filled with epoxy, the marker body having a base with large wetting parameter for shear and flexural strength , as disclosed in U.S. Pat. No. 4,726,706. The second roadway marker of this applicant, U.S. Pat. No. 5,927,897 developed a mean to increase the abrasion resistant of the reflective face by coating the reflective face with diamond-like film and by having holding pins extending from the partition walls into the body, the holding pins sealed by the filler material; this works very effectively. All of the above reflective pavement markers are incorporated herein by reference in their entireties. Applicant present goal to have a roadway marker with high reflectance, abrasion resistant, low cost, marker base area with good welding parameter and very simple yet consistent process to manufacture.
SUMMARY OF THE INVENTION
This invention provide a novel one piece raised roadway marker that comprises a monolithically injected body, together with one or two reflective faces and a base having large adhesive welding parameter for better adhesion to the pavement and higher resistance to flexural stresses .
The primary object of this invention is eliminate the multi steps process in prior arts for making reflective and non-reflective pavement markers while retaining maximum base surface area. Another objective of this invention is to provide a raised roadway marker made of high impact and abrasion resistant material with high impact resistance and good quality reflective index.
The present invention further provide a method of making one piece raised roadway marker of any desirable shape and configuration such as a marker with truncated body or one piece marker with a body having two rumble portions integrally made with two reflective faces and scalloped recess in-between with rectangular textured base.
In accordance with still further aspect of this invention, the marker can be made for one or two way traffic usage, having integrally built-in reflective faces, this will cost considerably less to install to the roadway, or two multi colored parts can be welded together, each with one reflective face opposite the other.
BRIEF DESCRIPTION OF THE DRAWINGS
The advantages and unique features of this invention will be better understood by reference to the drawings. These drawings are schematics, no scale used. In the drawings:
FIG. 1
is an isometric view of one of the preferred one piece pavement marker of the invention;
FIG. 2
is a plan view of the pavement marker illustrated in
FIG. 1
;
FIG. 3
is another isometric view of pavement marker in
FIG. 1
showing the base portion with grooved surface and the end opening for the hollow recesses;
FIG. 4
is a cross section view taken along the line
4
—
4
in
FIG. 2
;
FIG. 5
is an isometric view of a thin plate that can be used to seal the ends of hollow recesses;
FIG. 6
is a section view taken along the line
6
—
6
in
FIG. 4
showing partly grooved surfaces of a hollow recess;
FIG. 7
is an isometric view of another preferred embodiment of one-piece marker of the invention;
FIG. 8
is another isometric view of marker in
FIG. 7
showing the base surface;
FIG. 9
is an elevation view of the marker in
FIG. 7
showing the cursed sides and reflective cells;
FIG. 10
is a cross section view taken along the line
10
—
10
in
FIG. 9
;
FIG. 11
is an isometric view of yet another embodiment of one-piece marker of the invention;
FIG. 12
is a plan view of the marker in
FIG. 11
;
FIG. 13
is a cross section view taken along the line
13
—
13
in
FIG. 12
;
FIG. 14
is isometric view of the marker in
FIG. 11
showing the base surface and the back portion;
FIG. 15
is an isometric view of a sealing plate for the base of marker in
FIG. 11
;
FIG. 16
is an isometric view of two welded markers of
FIG. 11
;
FIG. 17
is a plan view of the marker in
FIG. 16
;
FIG. 18
is a cross section view taken along the line
18
—
18
in FIG.
17
.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Enhanced reflectivity, durability, cost effectiveness and simplified production method can be achieved by eliminating major steps or processes used in previous arts for the manufacturing of reflective and non reflective pavement markers. This invention is satisfying the above conditions.
This invention eliminate the process of metalizing, the reflective face; eliminate the step of welding a backing sheet to the reflective face; eliminate filling the marker body (shell) with inert filled resinous material or welding a unitarily molded block with flattened base to a shell; eliminate a lens mounting structure and a base layer added to marker body. This invention, simply developed a process of making a reflective pavement marker in one step process.
Referring to
FIGS. 1 through 6
represent one of the preferred embodiment of a durable one piece reflective marker designated by the number
200
which comprises an integrally cast body
210
with at least one reflective face
212
. Body
210
has a top portion
214
, two inclined sides
216
, two inclined planar faces
218
and
212
facing traffic with at least one (
212
) is a reflective face and a textured and grooved planar base surface
220
with an extended base portion
220
a
for added adhesion area. Marker
200
can be of any desired dimensions or shapes.
The inclined planar reflective face
212
integrally have planar surface
212
a,
multiple of reflective cells
230
and partition ribs
230
b
separating cells
230
from each other. Reflective cells
230
can be of any desired shape or size. Various reflective cells and cube corner reflective element designs available for use in this marker. The following U.S. Patents provide suitable cell and cube corner element designs, therefore, all of the following arts are incorporated as reference in their entireties: U.S. Pat. No. 3,712,706 to Stamm, U.S. Pat. No. 3,924,929 to Holmen, U.S. Pat. No. 4,208,090 to Heenan, U.S. Pat. Nos. 4,232,979 and 4,340,319 to Johnson, U.S. Pat. No. 4,498,733 to Flanagan, U.S. Pat. Nos. 4,726,706 and 5,927,897 to Attar. Reflective cell
230
has an outside planar surface
230
a
slightly recessed with respect to the planar surface
212
a
and the vertex of the partition ribs
230
b.
Preferably, the cell's outside surface
230
a
would be recessed anywhere between 0.005 to 0.020 inch below planar surface
212
a
to eliminate contact with automobile tires. Each reflective cell
230
have an inside surface
230
c
integrally built with multiple of protruding cube corner reflective elements. Each cell's inside surface
230
c
is isolated from each other by integrally built load carrying interior walls
310
which are tapered outwardly, integrally forming hollow recesses
300
directly beneath each inside surface
230
c
of the reflective cell
230
. Each hollow recess
300
is formed corresponding to the size and shape of the cell's inside surface
230
c
with the protruding cube corner reflective elements, said hollow recesses
300
positioned with their centerlines
500
near perpendicular to the cell's outside planar surface
230
a,
preferably this angle to be between 75 to 105 degrees. Each interior wall
310
form an angle (A) equal or less than 5 degrees with respect to each centerline
500
.
Hollow recesses
300
a
are used when the desired marker is to have only one side with reflective face, as shown in marker
200
. Both hollow recesses
300
and
300
a
will be tapered outwardly and open through the textured and grooved planar base surface
220
thereby forming air gab beneath each individual reflective cell
230
. Hollow recesses
300
and
300
a
can have some of the walls
310
formed with arcuate grooves
310
a
for added reflectivity, surface opaqueness, enhancing daytime reflectivity and improving the structural strength of the marker.
Marker
200
is made of a high impact resistance, transparent polymeric material, with ultra violet light stability. Thermoplastic such as high impact resistance acrylic, polycarbonate or any other high impact resistance engineered polymer is suitable for this marker. Reflective face
212
can have either three raw, two raw or one raw of reflective cells
230
, depending on the desired size, shape or height of marker
200
and the size and shape of the reflective cells
230
being used.
For applications in sunny and hot environment, where bituminous hot-melt adhesive may be used, to agglutinate marker
200
to the roadway. the low melting point of such adhesive material may lead to adhesive failure known as cookie cutter effect, where a marker agglutinated to the pavement, may be forced by traffic impact load to move away from it's intended location on the roadway.
The science of material welding teach us that one of the primary variables to good adhesion of two surfaces is the total surface area to be wetted by the adhesive (welding) material, this area can be called the (welding parameter), therefore, we can improve adhesion of marker
200
to a substrate and perhaps more effectively than the arts in U.S. Pat. No. 3,332,327 to Heenan or U.S. Pat. No. 5,340,231 to Steere. This improvement in welding parameter can be achieved by using one of various arcuate shapes with discontinuous length, grooved perpendicular to traffic direction. Each groove can have length of about an inch or less and textured surface, preferably by sand blasting the corresponding part of the tooling. The width or depth of such grooves should not be more than 0.10 inch in-depth.
It can be proving that the welding parameter can be increased considerably within the same marker base area despite the open ends of the hollow recesses
300
and
300
a,
as an example, consider marker
200
to have a base width of 4 inches and depth of 2.75 inches, therefore, the planar base surface area=2.75×4.0=11 sq. inches. In one of the preferred embodiment, assume the surface area for the same base area having 30 grooves, each having 0.09 inch diameter and 4.0 inch length, subtract 29 open end areas of hollow recesses
300
and
300
a,
each having open end area=0.08 sq. inch, hence, the net surface area=(30×4.0×0.09×3.14/2)−(0.08×29)=14.6 sq. inches. This is considerably larger than the same planar area with no grooves. Marker
200
will have even larger area as welding parameter by using short and discontinuous grooves, each near inch in length with textured surface. In addition, planar base surface
220
can have an extended portion
220
a
for added adhesive grip.
Yet another mean to improve the adhesive welding parameter of the grooved planar base surface
220
is by capping the open ends of hollow recesses
300
and
300
a
by a corresponding shaped plate
60
with corresponding size caps
65
and ties
66
, as in FIG.
5
. Unlike previous arts such as. in U.S. Pat. No. 5,340,231 to Steere and U.S. Pat. No. 5,667,335 to Khieu, the caps
65
used in the present invention will have textured discontinuous grooves and will be agglutinated to each corresponding hollow recess
300
and
300
a.
in such away leaving portion of each cap
65
recessed either slightly recessed or protruded within each opening of the hollow recesses
300
and
300
a
at the planar base surface
220
. The recessed depth shall be less than 0.10 inch from the planar base surface
220
.
In some application where the desired reflective marker is to have two opposite reflective faces integrally made within one piece body, a truncated body design can be used similar to marker
200
.
Another preferred embodiment is marker
100
, as shown in
FIGS. 7 through 10
. The body shape having one or two convex portions
40
, each having concave curve shaped front surface
41
, said front surface
41
integrally made having multiple of planar rectangular reflective cells
45
. Each reflective cell
45
integrally having an outside planar reflective surface
46
, which is slightly recessed below the vertex of partition ribs
47
separating reflective cells
45
from each other. Each integrally made cell
45
within marker body
100
having the outside planar surface
46
inclined approximately 30 degrees with respect to the marker planar base
48
. Each reflective cell
45
integrally having an inside surface
55
with protruding cube corner reflective elements. Marker
100
have two curved sides
62
.
The two convex portions
40
are connected with a concave portion
49
, said concave portion
49
need to be wide enough proportionately to marker's height to accommodate the space needed for the injection molding slides forming the cube corner reflective elements within each reflective cell
45
through the open end of each corresponding hollow recess
50
. Hollow recess
50
form an air gap beneath the cube corner reflective elements within the inside surface
55
of each cell. Each hollow recess is having centerline near perpendicular to the corresponding outside planar surface
46
of cell
45
.
Hollow recesses
50
are separated from each other by partition and load carrying walls
51
.
The planar base portion
48
of marker
100
has discontinuous curved grooves
48
a
with less than 0.09 inch in depth. The entire surface of the base
48
is textured to maximize the (adhesive wetting) welding parameter. The open ends of hollow recesses
50
can be capped with thin polymeric plate
52
.
Marker
100
may have slightly raised ridges
61
on the outside surface for added protection, such raised ridges forming either rectangular or rhombic shape grids on the convex portions
40
. The height of said raised ridges will be less than 0.010 inch.
In other applications where the desired marker to have two reflective faces with different color, shorter body depth, lower height or maximum welding parameter at the marker base area. In this case, an embodiment such as marker
10
and
10
a
are preferred, as illustrated in
FIGS. 11 through 18
. Marker
10
comprises of two identical shaped marker
10
a,
welded or glued together. The two sides of marker
10
can be of same color or two different colors.
Each marker
10
a
integrally consist of one inclined reflective face
110
, a top portion
121
, two multi-angled or curved sides
125
, a planar rectangular base surface
150
with textured discontinuous grooves, said base surface
150
can have an extended periphery portion
130
; and back portion
160
forming perpendicular angle with respect to the marker planar base surface
150
, said back portion
160
have hollow cavities
165
.
The reflective face
110
integrally has a planar surface
110
a,
multiple of reflective cells
115
and arcuate partition ribs
115
b.
Reflective cell
115
have outside planar surface
115
a
slightly recessed below the vertex or partition ribs
115
b
and an inside surface
115
c
with protruding cube corner reflective elements. Each inside surface
115
c
is open within a hollow recess
155
.
Hollow recesses
115
open through the base surface
150
. The centerline of each hollow recess
155
is near perpendicular to the corresponding cell's outside planar surface
115
a.
Each hollow recess
155
separated from each other by an outwardly tapered partition and load carrying walls
155
a.
It can easily be shown that marker
10
can have any desired shape or size and the reflective face can have either one raw or multipie raw of reflective cells, each cell having either hexagonal, rectangular, rhombic or circular shape or a marker with round base and spherical surface.
When additional welding parameter (area) is needed for the base surface
150
, the entire open ends of hollow recesses
155
can be capped by correspondingly shaped plate
60
, as in
FIG. 15
, with multiple caps
65
that can be welded onto it's corresponding size and shaped ends of hollow recesses
155
.
Caps
65
connected to each other by multiples of thin ties
66
, each with highly porous surface for adhesive penetration.
Marker
10
can be made welding the back side
160
of two identical parts
10
a
that can be produced connected by a thin wedge
166
. Wedge
166
can be tore apart so that two parts
10
a
with contrasted colors can be welded at the back side
160
, forming marker
10
.
Various embodiments of this invention can have improved abrasion resistant body, reflective cells or both, by applying one of various arts available in abrasion resistant coating. Preferably, using vacuum evaporator deposition of either silicon dioxide (SIO2) layer or a diamond like carbon layer, as in U.S. Pat. No. 5,927,897 to Attar; U.S. Pat. No. 4,060,660 to Carlson and U.S. Pat. No. 4,383,728 to Kieser, all of which are incorporated herein as reference in their entireties.
It is understood that various changes or modifications can be made within the scope of the appended claims to the above-preferred embodiments without departing from the scope and the spirit of the invention. Therefore, the invention can be practiced otherwise than as specifically described herein.
Claims
- 1. A monolithically formed one-piece reflective pavement marker comprising;a substantially hollowed pavement marker body, said marker body having a top, multiple sides, a planar base surface witn textured discontinuous grooves, two inclined faces, at least one of said faces being a reflective face, said reflective face integrally includes planar inside and outside surfaces with multiple reflective cells, said inside surfaces of reflective cells are open within hollow cavity air gaps immediately beneath said reflective cells, said hollow cavity air gaps being defined by multiple load carrying partition walls, said reflective cells can have any desired shape or size, said pavement marker being formed from high impact-resistant, transparent, polymeric material, said monolithically formed one-piece reflective pavement marker further comprising: plurality of integrally formed cube-corner reflective elements protruding from said inside surfaces of said reflective cells, said inside surfaces of reflective cells are open within said hollow cavity air gaps, wherein said integrally formed cube corner reflective elements provide said monolithically formed pavement marker the retro-reflectivity of light from oncoming traffic, said integrally formed load carrying interior walls are disposed rearward starting at the periphery of said inside surfaces of said reflective cells, said hollow cavity air gaps each having a centerline near perpendicular to the corresponding outside planar surface of said reflective cells, said hollow cavity air gaps having open ends at the planar base surface, said load carrying interior walls having slightly tapered surfaces starting at a point immediately adjacent to the periphery of the inside surfaces of said reflective cells, said load carrying interior walls are integrally formed having either smooth wall surfaces or surfaces with textures and arcuate grooves, said open ends of hollow cavities at the planar base surface can be sealed with a polymeric thin cap, whereby said load carrying interior walls define said inside surfaces of said reflective cells, provide the structural support for said hollowed pavement marker and defining the hollow cavity air gaps inclusively within said one-piece pavement marker.
- 2. The monolithically formed one-piece reflective pavement marker as defined in claim 1, wherein said pavement marker can have a truncated shape exterior surface with one reflective face, load carrying interior walls and a textured planar base surface, said reflective face integrally formed with reflective cells, said load carrying interior walls retaining said cube-corner reflective elements within said hollow cavity air gaps of said pavement marker.
- 3. The monolithically formed, one-piece reflective pavement marker as defined in claim 1, wherein the open ends of said hollow cavity air gaps at the planar base surface can be capped and sealed with a correspondingly sized and shaped polymeric thin cap, said cap having a textured and grooved surface, said cap sonically welded to the end portions of said load carrying interior walls within a recessed area of said planar base surface.
- 4. The monolithically formed one-piece reflective pavement marker as defined in claim 1, wherein either the entire exterior surface or said at least one reflective face of said pavement marker is coated with chemical vapor-deposited, abrasion resistant, layer of either silicone dioxide or hard carbon film.
- 5. The monolithically formed one-piece reflective pavement marker as defined in claim 1, wherein the planar base surface further comprises an integrally extended base portion, which extends beyond the periphery of the top surface of said pavement marker body.
- 6. A monolithically formed reflective pavement marker comprising:two parts, each part having one, inclined, planar, reflective face having multiple reflective cells; a planar top surface, two multi angled or arcuate sides, a planar base surface including textured grooves, a back side having a perpendicular angle with respect to the planar base surface, said backside having hollow cavities, said two parts connected by a thin wedge, said reflective cell having planar inside and outside surfaces to intercept light, said pavement marker being formed of high impact resistant transparent polymeric material; each of said two parts further comprising: multiple cube-corner reflective elements integrally protruding from said inside surface of said plurality of reflective cells, said multiple cube-corner reflective elements being disposed within hollow cavity air gaps, said cube corner reflective elements being adapted to provide retro reflective light toward on coming traffic, said hollow cavity air gaps having open ends at the planar base surface; load carrying interior walls which are an integral part of the inside surface of said inclined planar reflective face, said load carrying interior walls provide structural support and define said hollow cavity air gaps, said reflective cells can have either rectangular shapes, hexagonal, rhombic or circular shapes, said hollow cavity air gaps each having a centerline near perpendicular with respect to the corresponding outside planar surface of said reflective face, said interior walls tapered outwardly starting at a point immediately adjacent to the periphery of the inside surfaces of said reflective cells, said open ends of hollow cavity air gaps at the planar base surface can be sealed with a thin, polymeric, cap; said pavement marker further comprises a chemical vapor deposited, abrasion-resistant film of either hard carbon or silicone dioxide film, covering the reflective face or the outside surface of said pavement marker.
- 7. The monolithically formed reflective pavement marker as defined in claim 6, wherein the planar outside surfaces of said reflective cells can be at the same level of planar reflective face or be defined by partition ribs, said planar outside surfaces of reflective cells can be recessed about 0.001 to 0.01 inch bellow the apex of said partition ribs, said partition ribs reduce automobile tire contact with said reflective cells.
- 8. A reflective pavement marker comprising;said two parts of said pavement marker of claim 6, can be sonically welded or glued at the back sides there of, thereby providing a pavement marker with two opposing planar reflective faces, said pavement marker with two reflective faces can have the two reflective faces with similar color or dissimilar colors for each side of said marker.
- 9. The monolithically formed reflective pavement marker as defined in claim 6, wherein the open ends of said hollow cavity air gaps at the planar base surface can be capped and sealed with a correspondingly sized and shaped thin cap made of compatible polymeric materials, each cap having a textured and grooved surface.
- 10. The monolithically formed reflective pavement marker as defined in claim 6, wherein, said load carrying interior walls are integrally formed having either smooth surface walls or walls having arcuate grooves to increase color appearance and added structural strength.
US Referenced Citations (14)
Foreign Referenced Citations (2)
Number |
Date |
Country |
004112702 |
Oct 1992 |
DE |
WO9111787 |
Feb 1990 |
GB |