Base for Turf System with Vertical Support Extensions at Panel Edges

This application is a continuation patent application of U.S. patent application Ser. No. 18/378,328, filed Oct. 10, 2023. U.S. patent application Ser. No. 18/378,328 is a continuation patent application of U.S. patent application Ser. No. 17/468,140, filed Sep. 7, 2021; now U.S. Pat. No. 11,781,272, issued Oct. 10, 2023. U.S. patent application Ser. No. 17/468,140 is a continuation patent application of U.S. patent application Ser. No. 16/667,072, filed Oct. 29, 2019; now U.S. Patent No. 111,111,636, issued Sep. 7, 2021. U.S. patent application Ser. No. 16/667,072 is a continuation patent application of U.S. patent application Ser. No. 16/114,858, filed Aug. 28, 2018; now U.S. Pat. No. 10,458,075, issued Oct. 29, 2019. U.S. patent application Ser. No. 16/114,858 is a continuation patent application of U.S. patent application Ser. No. 15/157,528, filed May 18, 2016; now U.S. Pat. No. 10,060,082, issued Aug. 28, 2018. The disclosure of these applications are incorporated herein by reference in their entirety.

This invention relates in general to artificial turf systems of the type used in athletic fields, ornamental lawns and gardens, and playgrounds.

Artificial turf systems are commonly used for sports playing fields and more particularly to artificial playing fields. Artificial turf systems can also be used for synthetic lawns and golf courses, rugby fields, playgrounds, and other similar types of fields or floor coverings. Artificial turf systems typically comprise a turf assembly and a foundation, which can be made of such materials as asphalt, graded earth, compacted gravel or crushed rock. Optionally, an underlying resilient base or underlayment layer may be disposed between the turf assembly and the foundation. The turf assembly is typically made of strands of plastic artificial grass blades attached to a turf backing. An infill material, which typically is a mixture of sand and ground rubber particles, may be applied among the vertically oriented artificial grass blades, typically covering the lower half or ⅔ of the blades.

This invention relates to a turf underlayment layer configured to support an artificial turf assembly. The underlayment layer comprises plurality of panels, each panel comprising a core with a top side and a bottom side. The top side has a plurality of top projections. The top projections form top side water drainage channels. The panels have edges, with the edges of one panel abutting the edges of adjacent panels, thereby forming a drainage path between adjacent panels. The panel edges have vertical support extensions that extend into the drainage paths between adjacent panels. The vertical support extensions have an upper surface for supporting an artificial turf assembly overlying the turf underlayment layer, and the panel edges having one or more complementary indentations corresponding to vertical support extensions of adjacent panels. When the panels move toward each other, thereby closing drainage paths between adjacent panels, the vertical support extensions are received in the corresponding indentations.

According to this invention, there is also provided a turf underlayment layer for supporting an artificial turf assembly. The turf underlayment layer includes a plurality of panels assembled together. Each panel includes a core, a top side having a plurality of projections, and a bottom side, the top projections forming top side water drainage channels. The panels have edges, with the edges of one panel abutting the edges of adjacent panels. The panel edges have a non-linear shape, with the non-linear shape of the panel edges being complementary to the non-linear, non-interlocking shape of adjacent panel edges. At least one of the panel edges has one or more drainage projections, the drainage projections spacing the abutting panel edges apart, with the resultant spacing of the edges of abutting panels forming a drainage path at the intersection of the abutting panels. The drainage paths are non-linear because of the nonlinear shape of the panel edges.

According to this invention, there is also provided a turf underlayment panel suitable for assembly with additional turf underlayment panels to form a turf underlayment layer for supporting an artificial turf assembly. The turf underlayment includes a core, a top side having a plurality of top projections, and a bottom side, the top projections forming top side water drainage channels. The panels have edges, with the edges suitable for abutting the edges of adjacent panels, thereby forming a drainage path between adjacent panels. The edges of the panel have vertical support extensions that extend from the panel, the vertical support extensions having an upper surface for supporting an artificial turf assembly overlying the panel. At least one of the panel edges has one or more complementary indentations corresponding to vertical support extensions of adjacent panels, wherein when the panel is assembled with an adjacent panel, the vertical support extensions can be received in indentations in the adjacent panel.

Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

The artificial turf system shown inis indicated generally at. The turf system includes an artificial turf assembly, an underlayment layerand a foundation layer. The foundation layercan comprise a layerof crushed stone or aggregate, or any other suitable material. Numerous types of foundation layers are known to those skilled in the art. The crushed stone layercan be laid on a foundation base, such as compacted soil, a poured concrete base, or a layer of asphalt paving, not shown. Alternatively, the underlayment layermay be applied over the asphalt or concrete base, omitting the crushed stone layer, if so desired. In many turf systems used for an athletic field, the foundation layers are graded to a contour such that water will drain to the perimeter of the field and no water will pool anywhere on the surface.

The artificial turf assemblyincludes strands of synthetic grass bladesattached to a turf backing. An optional infill materialmay be applied to the grass blades. The synthetic grass bladescan be made of any material suitable for artificial turf, many examples of which are well known in the art. Typically, the synthetic grass blades are about 5 cm in length although any length can be used. The bladesof artificial grass are securely placed or tufted onto the backing. One form of blades that can be used is a relatively wide polymer film that is slit or fibrillated into several thinner film blades after the wide film is tufted onto the backing. In another form, the bladesare relatively thin polymer films (monofilament) that look like individual grass blades without being fibrillated. Both of these can be colored to look like blades of grass and are attached to the backing.

The backing layerof the turf assemblyis typically water-porous by itself, but is often optionally coated with a water-impervious coatingA, such as for example urethane, for dimensional stability of the turf. In order to allow water to drain vertically through the backing, optionally the backing can be provided with spaced apart holesA. In an alternative arrangement, the water impervious coating is either partially applied, or is applied fully and then scraped off in some portions, such as drain portionB, to allow water to drain through the backing layer. The bladesof grass fibers are typically tufted onto the backingin rows that have a regular spacing, such as rows that are spaced about 2 centimeters to about 4 centimeters apart, for example. The incorporation of the grass fibersinto the backing layersometimes results in a series of spaced apart, substantially parallel, urethane coated corrugations or ridgesB on the bottom surfaceof the backing layerformed by the grass blade tufts. RidgesB can be present even where the fibers are not exposed.

The optional infill materialof the turf assembly, when applicable, is placed in between the bladesof artificial grass and on top of the backing. If the infill materialis applied, the material volume is typically an amount that covers only a bottom portion of the synthetic grass bladesso that the top portions of the blades stick out above the infill material. The typical purpose of the optional infill materialis to add stability to the field, improve traction between the athlete's shoe and the play surface, and to improve shock attenuation of the field. The infill materialis typically sandA or ground up rubber particles or synthetic particulateB or mixtures of these, although other materials, including natural material, can be used.

When the backing layerhas holesA or a porous sectionB for water drainage, then some of the infill materialis able to wash or filter through the backing layer porous sectionB or the backing layer drainage holesA and onto the turf underlayment layer. This infill migration, or migration of the infill constituents, is undesirable because the depletion of the infill materialresults in a field that doesn't have the initially designed stability and firmness characteristics. Excessive migration of the infill material, or the infill constituent components, to the turf underlayment layercan create a hard layer which makes the whole turf system less able to absorb impacts.

The turf underlayment layeris comprised of expanded polyolefin foam beads, which can be expanded polypropylene (EPP) or expanded polyethylene (EPE), or any other suitable material. The foam beads are closed cell (water impervious) beads. In one optional method of manufacture, the beads are originally manufactured as tiny solid plastic pellets, which are later processed in a controlled pressure chamber to expand them into larger foam beads having a diameter within the range of from about 2 millimeters to about 5 millimeters. The foam beads are then blown into a closed mold under pressure so they are tightly packed. Finally, steam is used to heat the mold surface so the beads soften and melt together at the interfaces, forming the turf underlayment layeras a solid material that is water impervious.

Other methods of manufacture can be used, such as mixing the beads with an adhesive or glue material to form a slurry. The slurry is then molded to shape and the adhesive cured. The slurry mix underlayment may be porous through the material thickness to drain water away. This porous underlayment structure may also include other drainage features discussed below.

The final EPP material can be made in different densities by starting with a different density bead, or by any other method. The material can also be made in various colors. The resulting underlayment structure, made by either the steam molding or the slurry mixing processes, may be formed as a water impervious underlayment or a porous underlayment. These resulting underlayment layer structures may further include any of the drainage, deflection, and interlocking features discussed below.

In the embodiment illustrated in, the turf underlayment layeris comprised of a plurality of underlayment panelsA,B, andC. Though shown as three interlocked panels, it is to be understood that the underlayment layerincludes a sufficient number of panels to cover the desired area intended to be covered by the artificial turf surface system. Each of the panels has side edgesA,B,C, andD. Side edgesB andD have a cutout and tab configuration so that the panelsA,B, andC can be mated and or interlocked together to form the underlayment layer. The side edgesB andD optionally can be configured with dovetail shapes to form an interlocking structure, or can have any other suitable edge configuration. The side edgesA andC are configured to be mated together to form drainage pathswhen the panels are arranged into a turf underlayment layer. The panelsA,B andC further have substantially planar major faces, i.e., top sideand bottom side. Between the top sideand the bottom sideis the core.

Optionally the bottom sideincludes a plurality of bottom side drainage channels. Also, optionally, the underlayment panelincludes drain holesconnecting the top side water drainage channels to the bottom side water drainage channels for fluid communication between the panel top sideand bottom side.

As shown in, the underlayment layer panel includes top projectionsA and optional bottom projectionsB. The thickness of underlayment panelis defined as the thickness of the coreof the panel plus the thickness of the top projectionsA plus the thickness of any bottom projectionsB. The top projectionsA support the overlying turf assemblyand also define top drainage channels for the flow of water across the panel.

As shown in, where the edges of one panel, such as panelA, abut the edges of an adjacent panel, e.g.B, a joint or drainage pathis formed. One advantage of the drainage pathis to allow the passage of water from the top sideof the panel to the bottom sideof the panel. In order to prevent the sagging or depression of the turf assemblyinto the trough or depression of the drainage path, vertical support extensionsare provided at the edgesB andD of the panels. The vertical support extensionshold up the overlying turf layer and prevent the possibility of having the overlying turf layer from sagging into the valley-like drainage path. The use of the vertical support extensionsavoids the situation where the outline or pattern of the drainage pathsis telegraphed onto the overlying artificial turf layer. The vertical support extensionsextend into the drainage pathsbetween adjacent panels.

As shown in, the vertical support extensionshave an upper surfacefor supporting an artificial turf assemblyoverlying the turf underlayment layer. This support for the artificial turf assembly substantially prevents sagging of the artificial turf assemblyinto the drainage path. In order to accommodate thermal expansion and other forces that would tend to move adjacent panelsA,B andC toward each other and would then trend to narrow the drainage paths, the panel edges have one or more complementary indentationscorresponding to vertical support extensionsof adjacent panels. As adjacent panels move toward each other, thereby closing drainage paths between adjacent panels, the vertical support extensionsare received in the corresponding indentations, and the vertical support extensionssubstantially do not provide resistance to the movement of the panels toward each other. In the alternative, the vertical support extensionsand corresponding indentationscould be configured to provide a measured or planned amount of resistance to the movement of the panels toward each other. As can be seen in the embodiment shown in, at least one of the edges of the panels has both vertical support extensionsand indentationsin the same edge. It is to be understood that there does not need to be a 1 for 1 correspondence between the vertical support extensions and the indentations. Some of the vertical support extensionsmay not have a corresponding indentation in the adjacent panel.

As shown in, the vertical support extensions have an extension portionthat extends into the into the drainage path. The extension portioncan have a top surface shape that is substantially rectangular as shown in. Alternatively, the extension portioncan have semicircular top profile when viewed from the top. As shown in, in another embodiment the extension portion can have a cantilevered configuration. Also, the extension portioncan have a tapered side profile configuration as shown in. It is to be understood that whatever the shape of the vertical support extensionand the extension portion, the indentationmatches the shape to allow the indentationto receive the vertical support extension.

As can be seen in, the vertical support extension has a uniform horizontal cross-sectional area throughout its height. In other embodiments, such as the tapered vertical support extensionshown in, there is a non-uniform horizontal cross-sectional area throughout the height of the vertical support extension. In the case of the tapered vertical support extension shown in, there is a greater horizontal cross-sectional area at the upper end of the vertical support extensionthan at the lower end.

An optional feature of the underlayment panels is one or more drainage projectionsthat extends from the edge of the panelsA,B,C, andD. The drainage projectionsmaintain the separation of adjacent panels from each other, thereby helping to define the width of the drainage path. The drainage projections are crushable so that they can accommodate movement of adjacent panels toward each other when caused by thermal expansion or other forces or mechanisms. In contrast to the vertical support extensions, the drainage projectionsdo not have corresponding recessesin the adjacent panel.

There is another mechanism that can be used to support the turf assemblyand prevent it from sagging or dropping into the drainage path. As shown in, the edgesAA andCC of panelsAA andBB are non-linear. The result of non-linear panel edges is a non-linear drainage pathAA that can provide support for the turf assemblywithout the use of the vertical support extensions. It is to be understood that vertical support extensions can also be used with a non-linear drainage channel. The shape of the non-linear edge can be any shape suitable for supporting the overlying turf assembly. In one embodiment, the non-linear panel edges are wavy, making the drainage pathsAA wavy. In another embodiment, the panel edges have a non-linear shape, with the non-linear shape of the panel edges being complementary to the non-linear, non-interlocking shape of adjacent panel edges.

The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.