Construction of a foamed polymeric manhole chimney

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TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION

The present invention relates to a construction of a manhole chimney. More specifically, the present invention relates to a foamed polymeric adjustment or grade ring that is used to construct the manhole chimney.

BACKGROUND OF THE INVENTION

Generally, the construction of a manhole includes an underground horizontal main sewer line having vertical access pipes or sections connected to the main sewer line which lead to a truncated cone and ultimately to a manhole frame and cover. On top of the cone a manhole chimney or adjustment courses are constructed which lead upward and are of the same diameter as the upper surface of the cone. The manhole frame is placed on top of this chimney and holds the manhole cover.

Past constructions of the manhole chimney or adjustment courses included using brick and mortar to build up the manhole chimney or in the alternative precast concrete rings have been used which are stacked on top of one another. The state of the art is generally shown in the following cited references: U.S. Pat. No. 1,639,495 issued to Frame; U.S. Pat. No. 3,926,533 issued to Binette; German Patent No. 2,525,285; U.S. Pat. No. 4,121,390 issued to Hall; U.K. Patent No. 2,088,446; U.K. Patent No. 2,102,479, U.S. Pat. No. 4,408,421 issued to Pai; and U.S. Pat. No. 4,469,467 issued to Odill, et al.

Upon completion of the construction, the surrounding surface is back filled, and the upper surface is paved such that the manhole is generally flat with the surrounding roadway surface. In areas other than streets the top of the cover is also generally adjusted to the surrounding ground level.

Because of the numerous and varying stresses on these constructions, manhole chimney constructions of the past have been prone to rapid deterioration. For instance, the hydrogen sulfide gas and other chemicals commonly found in sewer systems, may be corrosive to cement and may tend to deteriorate the preformed rings or the cement that holds the brick constructions together. In addition, the freeze-thaw cycles of the surrounding ground place strong pressure on the construction and may crush the construction. These freeze-thaw cycles may also work to widen any cracks or deformations in the structure thereby breaking down the structure. Also jolts or shock waves produced by passing traffic and road scrapers accentuate the destructive forces acting on the construction thereby breaking down the construction even sooner. Because of these and other problems the integrity of the structure is eventually broken such that water and sediment may be permitted to flow through the manhole chimney and into the sewer system.

This process is called inflow and is undesirable in a sewer system in that these sediments may cause clogging of the sewer system or create undesirable conditions for workers working inside the sewer system. In addition, inflow may soon result in a void in the underlying support of the roadway surface were the sediment has entered through the breaches in the manhole chimney, which may then cause structural problems with the roadway surface since it is not supported where the void occurs.

The precast spacing rings of the past have also been troublesome to install in a manhole chimney. These precast rings are heavy and require heavy equipment or several men to install. In addition these rings tend to be somewhat fragile and may shatter or crack if dropped or mishandled.

In the past, constructions have been attempted wherein seals have been placed between the precast ring in an attempt to stop the inflow problem. In addition, as disclosed in U.S. Pat. No. 4,469,467 issued to Odill and assigned to Cretex Companies, manhole chimney seals have been attempted which seal the manhole chimney by a rubber tubular seal placed either on the inside or the outside of the manhole chimney. However, these constructions may still allow freeze-thaw damage or other damage to the chimney construction to occur.

SUMMARY OF THE INVENTION

The present invention provides an adjustment ring, or grade ring, for use in a construction of a manhole chimney that includes at least one continuous polymeric foam grade ring coated with a weatherable and strength enhancing coating that can be stacked one on another for providing a construction of the chimney portion of a sewer system.

It is an object of the present invention to provide a chimney construction which is free from inflow and which is resistant to chemicals, freeze-thaw damage, inflow, and which will absorb road shock from passing automobiles and road scrapers and retain its structural integrity.

It is a further object of the present invention to provide a lightweight yet rigid and durable adjustment ring for use in the construction of a manhole chimney and which will provide economical installation and would not be prone to damage from mishandling or dropping of the ring.

Other objects and advantages of the present invention will become apparent upon considering the following detailed description and appended claims, and upon reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall view partially broken away of a manhole chimney construction of the present invention;

FIG. 2 is a detailed cross sectional view of the elastomeric ring construction of a manhole chimney, of the present invention;

FIG. 3 is a detailed cross sectional view of an alternate construction of a manhole chimney of the present invention;

FIG. 4 is an exploded view of a manhole chimney construction of the present invention;

FIG. 5 is a cross sectional view of an embodiment of the elastomeric ring of the present invention; and

FIG. 6 is a cross section view of an embodiment of the elastomeric construction ring of the present invention.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

According to the present invention, there is provided an adjustment ring, or grade ring, for use in the construction of a manhole chimney assembly, generally indicated as 10. More specifically, continuous polymeric foam grade rings 12 are provided for stacking one on another, thus providing a construction of the chimney portion of a manhole access to a sewer system 14.

The sewer system 14 includes a main sewer line (not shown) that has vertical access pipe or riser 18 rising from it and leading to a cone 20. The invention of the chimney assembly 10 is generally constructed on top of the cone 20. In the present invention the continuous polymeric foam construction rings 12 are stacked one on another, and the frame 22 of the manhole cover 24 is placed on top of the uppermost polymeric foam construction ring 12. The number of rings 12 and thickness of the rings may vary depending upon the application. Rings 12 are preferably formed at thicknesses including but not limited to one-half inch, one inch, two inches, four inches and six inches.

Referring now to FIG. 5, in one preferred embodiment of the present invention, the continuous polymeric foam construction grade rings 12 are formed having an upper surface 30 and a lower surface 32, with the upper surface 30 including annular grooves 28, 29 and the lower surface 32 including male portions 34, 36 that correspond in size and shape with the respective grooves 28, 29. It is preferable that the upper surface 30A of the topmost ring 12A contains no grooves 28, 29 to provide an increased seal to the manhole frame 22. Further, it is preferably that the lower surface 32A of the bottommost ring 12B contain no male portions 34, 36, thus providing an increased seal between the bottommost ring 12B the cone 20.

When the one or more polymeric foam rings 12 are placed on top of the cone 20 of a sewer system 14 initially a layer of mastic may be placed between the cone 20 and the bottommost ring 12B. Thereafter, the polymeric foam rings 12 are stacked one upon another with the male portions 34, 36 positioned within the respective annular grooves 28, 29 between adjacent rings 12 until the level of the upper surface of the manhole frame 22 is even with the roadway surface 23 or ground level. The manhole frame 22 is then placed on top of the topmost construction ring 12A that is then back filled and paved around, thereby holding the frame 22 in place.

Optionally, as shown in FIG. 3, mollies 38 are provided in the cone 20, and the frame 22 has corresponding holes 39 that would allow bolts 40 to secure the system together. Therefore, the polymeric foam rings 12 may be accompanied by a series of aligned vertical holes 42 through which bolts 40 are placed to hold the frame 22 onto the cone 20.

As shown best in FIG. 6, the polymeric foam rings 12A, 12 and 12B (Ring 12A is represented in FIG. 6) of the present invention, as described above, have a polymeric foam core 50 having suitable strength, flexibility and durability for use in the construction industry. The polymeric foam rings 12 are lightweight and thus are easy to transport and assemble. The polymeric foam core of the rings 12 is formed in any number of processes well known to those of ordinary skill in the art of forming foam materials. Thus, techniques such as open pour molding, casting, or injection molding may be utilized.

A polymeric coating 52 is applied to the entire outer surface 51 of the core 50 to act as a barrier layer and to enhance the mechanical properties of the rings 12. As such, the polymeric foam rings are structurally sound, absorb shock, and are generally impervious