The present invention relates to molded plastic chambers having arch shape cross sections, for receiving, containing and dispersing stormwater when buried beneath the surface of the earth.
Arch shape cross section storm chambers made from injection molded plastics have been used for a number of years to handle stormwater. In a typical installation, multiple rows of strings of interconnected chambers are placed on the floor of a cavity made in the earth surface and are then backfilled with crushed stone or the like. Stormwater, such as might run-off from a paved parking lot or roofs of buildings is channeled to the chambers so the waters can accumulate and then be dispersed over time by either percolation into the surrounding soil or by controllably flowing to a water course.
Some types of arch shape cross section chambers, exemplified by a corrugated chamber described in Detullio U.S. Pat. No. 5,087,151, have closed ends and are interconnected by pipes. Those chambers might be made by thermoforming of thermoplastic sheet. Another type of chamber, of more relevance to the invention described herein, is exemplified by the chambers shown in Kruger U.S. Pat. No. 7,118,306. Those kinds of chambers are preferably made by injection molding. The chambers have open ends. A string of chambers is assembled by overlapping a first end of one chamber on the second end of a like chamber, when the like chamber has been previously placed within a cavity in the earth. After installation, the chambers are backfilled, typically with crushed stone, and the stone is covered to create a soil surface, often a paved surface which can be used by motor vehicles.
When so installed beneath the surface of the earth, stormwater chambers should have requisite strength and durability, particularly for bearing the overlying load of soil and any vehicular or other traffic.
Systems comprised of molded plastic arch shape cross section stormwater chambers are in functional- and cost-competition with other stormwater systems, including buried systems comprised of steel conduit and detention ponds. Generally, it is an objective to have storm chambers with larger and larger volumetric capacity per unit length, while of course still meeting the load bearing requirements. Whereas early plastic chambers used 20 years or more ago had a peak height of 12 inches, more recent chambers may be quite large. For example, a commercial Model 4500 stormwater chamber sold by Stormtech LLC, Rocky Hill, Conn. is 100 inches wide at the base, about 60 inches high, about 48 inches long, and weighs about 120 pounds. There is a generalized desire to commercialize even larger chambers.
There are practical problems encountered with large chambers. Among them are: First, it is not easy to mold large chambers because they require large molding machines and machinery for handling the just-molded products. Large and thus less common injection molding machines can be costly.
Second, large chambers present problems with respect to storing and shipping in economic fashion by truck —the most common mode. Typically chambers are nested one within the other to form a stack for shipment on pallet. But the basic height of a chamber is large to begin with, then that means not many chambers can be nested before the height capacity of a ordinary highway truck is exceeded. For example, if the load height capacity of a truck is about 100 inches from the bed surface, and one chamber is 60 inches high, then there is only an about 40 inches of space for containing nested chambers. If the stack height is about 6 inches (the spacing between one chamber and next-nested chamber), then only 6-7 chambers can be stacked on top of the bottom chamber.
Third, the weight of each individual chamber can exceed that which workers can handle manually, particularly at the site where the stormwater system is being constructed, necessitating the use of materials handling equipment. It is more convenient for installers to not have to use lifting devices.
An object of the invention is to provide large stormwater chambers which have improved characteristics with respect to manufacturability, shipment and handling. Another object is to provide a chamber and associated handling shipping method which minimizes storage and shipping costs.
In accord with the present invention, a stormwater chamber is comprised of two half chambers. Half chambers of the present invention may be stacked as a nested multiplicity of half chambers on a pallet or the like for economical shipping, particularly by means of a motor vehicle transport truck. At or near the point of use, the half chambers are mated at coupling features to form a chamber which is in use configuration and which has a joint at the top of the chamber. Preferably, the half chambers are substantially identical and are made in the same mold.
Different embodiments of coupling features and joints may be used. Typically the joint is comprised of mating flanges, intermittent or continuous, which run along the length of the top of the chamber. The flanges may interlock, Clamps and latching means may be used to hold the half chambers relative to each other while they are handled and until they are buried in soil or the like for use.
The foregoing and other objects, features and advantages of the present invention will become more apparent from the following description of preferred embodiments and accompanying drawings.
Embodiments of chambers of the present invention are preferably made of injection molded thermoplastic, preferably a polyolefin such as polyethylene or polypropylene. Exemplary chambers are comprised of half chambers which join to each other by coupling means at a joint proximate the top of the chamber.
Stormwater chambers and their use have been described in the art. In particular, reference may be made to commonly owned U.S. Pat. No. 7,118,306 of Kruger et al., entitled “Stormwater Management System” and U.S. Pat. No. 6,991,734 of Smith et al, entitled “Solids Retention in Stormwater System.” The disclosures of the foregoing patents are hereby incorporated by reference. When a chamber is buried within crushed stone or other soil material the arch shape of the chamber cross section maintains the integrity of the interior cavity of the chamber. Simply stated, the vertical forces of the stone, soil, and anything on the surface of the soil, are transferred along the curve of the arch to the base flanges. As is characteristic of arches (for instance, arches comprised of stone or brick pieces), there need not be significant capacity to bear shear forces within the curved structure in order to maintain the integrity of the structure once it is in place and subjected to foregoing kind of vertical loads. Thus, it will be appreciated that in the present invention the joint 20 at the top of the chamber need not have strength to resist high shear load. However, a joint will desirably have sufficient shear strength to enable lifting and other handling of a chamber, to move it from the point of assembly to its position within a to-be-filled cavity in the earth.
In one embodiment, half chambers are mechanically interlocked and optionally welded or otherwise secured at coupling features in vicinity of the joint. When the joint is planar it is preferably in the vertical center plane CP. When the joint is non-planar, the joint will be in proximity of the vertical center plane, with parts of the joint somewhat offset from the plane.
When half chamber 22 and half chamber 24 are engaged with each other, the upper end of half chamber 24 rests on the surface of the serpentine lip 30. Flange 28 has a multiplicity of horizontally extending pins 34 which fit into the female cavities of sockets 32 on the flange 26, to help align the coupling features with each other. The pin-socket engagements provide some shear strength to the joint.
Optionally, as shown in
While welding is preferred with the
While the joint is preferably formed at the at the center plane of the chamber, as has been shown in several embodiments here, in the generality of the invention the joint may be offset transversely somewhat from the center plane; and thus the term half chamber in such instances would be construed in nominal and not exact terms.
In one method of making and shipping chambers within the scope of invention, when half chambers are molded, they may be mated and optionally welded in the factory and shipped as one piece chambers.
Alternatively, in another method of making and shipping chambers, half chambers may be shipped to an assembly point remote from the point of molding on a pallet 80 (or equivalent device) as a nested stack 82 as shown (for representative half chambers 24) in
The invention enables more compact and economic shipping, by shipping unassembled half chambers, compared to shipping whole chambers. The invention also enables fabrication of large chambers which are beyond the plastic-weight molding capacity of, or the platen size of, a particular injection molding press, where the half chamber is within such capacity.
The present invention has relationship with the invention of a commonly owned provisional application 61/700,315 of Moore, Jr. et al., and a non-provisional patent application claiming benefit of same, bearing Ser. No. 14/025,773, entitled “Molded Plastic Stormwater Chamber Having a Hinged Top Joint,” filed on even date herewith. The disclosures of both applications are hereby incorporated by reference. The related applications describe chambers which are made from half chambers, where the half chambers are connected to each other by one or more hinge joints at the top of the chamber. Application Ser. No. 14/025,773 describes ways of locking one hinged half chamber to a mating hinged half chamber. The locking means, and in particular a longitudinal running locking rod, may be used in the present invention. The application also describes preferred ways of molding half chambers, so the resultant chambers are well-suited to overlapping end-to-end installations. That method of making may be used in the present invention.
The invention, with explicit and implicit variations and advantages, has been described and illustrated with respect to several embodiments. Those embodiments should be considered illustrative and not restrictive. Any use of words which relate to the orientation of an article pictured in space are for facilitating comprehension and should not be limiting should an article be oriented differently. Any use of words such as “preferred” and variations thereof suggest a feature or combination which is desirable but which is not necessarily mandatory. Thus embodiments lacking any such preferred feature or combination may be within the scope of the claims which follow. Persons skilled in the art may make various changes in form and detail of the invention embodiments which are described, without departing from the spirit and scope of the claimed invention.
This application claims benefit of provisional patent application Ser. No. 61/700,313, filed Sep. 12, 2012.
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Number | Date | Country | |
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61700313 | Sep 2012 | US |