The Prior Art Fireplaces have been used in homes over the years for providing heat as well as to provide a desired ambience. While wood and coal have been the primary fuels for burning in fireplaces, there is an increasing demand for synthetic or artificial fireplace logs. These logs are easier to purchase and store, provide better Btu/lb value than wood or coal, are easier to light, safer to use with virtually no maintenance during burning, and can be used to build fires of a known duration, generally from 2 hours to more than 6 hours.

Artificial or synthetic logs are usually manufactured by combining a carrier material, usually particles of cellulosic origin, with a combustible binder/fuel. The cellulosic material may be sawdust, or a mixture of sawdust with other combustible materials of varying proportion. The binder typically consists of suitable blend of waxes, either alone or in combination with other combustible materials. Following thorough mixing of the ingredients, the resulting mixture is formed into suitable, log-like shapes by extrusion, molding or compression, in either a batch or continuous process.

Certain cellulosic fibers in artificial or synthetic firelogs exhibit not only poor burning characteristics, but also contribute to the formation of a smoldering core.

The poor burning manifests itself in the form of subdued burning in excess of 5 hours, and leaves a smoldering core on the grate after the flame goes out. The continued presence of the smoldering core is compounded by the fact that manufacturers of artificial fireplace logs usually specify that only one firelog be burned in the fireplace, and that the fireplace not be poked or disturbed in any way during its entire burn. This is done to prevent a flare-up resulting from a broken firelog, and to prevent embers from sticking to the poker.

A smoldering core left on the grate after the flame goes out is not only unsightly, but may contribute to smoke entering the house. This is because the small amount of heat produced during the active burning phase, as well as by the core, in some cases, may not be enough to maintain a proper draft as the chimney cools. An analysis of the combustion emissions shows that the emission of carbon monoxide (CO) peaks just about when the flame goes out, and that significant amounts of CO continue to be generated for a long time, as long as a smoldering core remains on the grate. CO is an odorless, highly toxic gas, and is classified by the Environmental Protection Agency (EPA) as a Criteria Pollutant. The National Ambient Air Quality Standard (NAAQS) for CO is 9 parts per million (ppm) in a period of 8 hours, and 35 ppm in a 1-hour time period. Residential indoor levels of CO are also of concern because of a trend toward the construction of airtight, energy-efficient residences. In such residences, an unbalanced exhaust ventilation system subjects them to a negative pressure (-5 to-7 pascals) just enough to overcome the weak draft established by the smoldering core, thus drawing combustion emissions into the structure and exacerbating the problem. Thus, the faster the core burns out, the less likely it is that these problems occur.

There exist artificial firelogs whose outer surfaces have longitudinally extending grooves, indentations or slots for various purposes. For example, U. S.

Patent 5,858,032 discloses a composite, extruded solid fuel block having a generally

rectangular profile in transverse cross section with rounded edges and concave or scalloped indentations in each of the four sides of the profile. The scalloped indentations are said to provide a high external surface area to volume ratio and also allow the blocks to stack stably on one another and on other fuel without slipping. A high external surface area to volume ratio is said to allow a relatively high rate of burning and/or higher flames than would otherwise be possible. U. S.

Patent 4,478,601 discloses a stackable fuel block having a base that is concave to provide an air entry passageway when the block is positioned to be burned on one of its flat surfaces. The top or opposite face of the block is congruently convex to the base to permit stacking the individual blocks both in storage and use. U. S. Patents 4,040,796; 4,043,765; 4,104,034; 4,243,394; 4,326,854; 4,883,498; and 5,858,036 are examples of patents disclosing artificial firelogs having longitudinally extending grooves along the upper and/or side surfaces, or along the rear bottom edge, to improve ignition and flame spread. It is also known that grooves may be used for controlling the weight of artificial firelogs.

SUMMARY OF THE INVENTION Broadly, the present invention provides an environmentally-responsible artificial firelog with reduced emission of total CO and improved performance.

More particularly, an artificial firelog pursuant to the invention reduces tail end CO emissions by shortening the CO emission time at the end of the burn.

In accordance with a preferred embodiment of the invention, there is provided a low total carbon monoxide emission artificial firelog comprising an elongated flammable body having a bottom, longitudinally extending face adapted to rest on a grate during use of the firelog. The bottom face defines a longitudinal groove extending the length of the firelog. During combustion of the firelog, total carbon monoxide emission is substantially less than the total carbon monoxide emission of the same firelog without the-groove. Preferably, the groove has a

transverse cross section that is substantially uniform along the entire length of the firelog.

In accordance with a specific, exemplary embodiment of the invention, the longitudinal groove is defined by generally vertical parallel longitudinally extending side surfaces and a concave or arched top surface extending between the side surfaces. Alternatively, the groove may have a generally rectangular transverse cross section. In accordance with another specific embodiment of the invention, the groove may have a generally inverted V-shaped cross sectional configuration.

Pursuant to yet another specific embodiment, the groove has a generally trapezoidal cross section with the longer base thereof extending along the bottom face of the firelog. Still other alternative cross sectional configurations may be provided.

During use of the firelog of the present invention, the firelog is placed on a fireplace grate with the bottom, grooved face resting on the grate. The firelog is then ignited. Besides reducing the total amount of carbon monoxide generated, the groove further allows combustible gases to collect in the groove space, helps spread the flame, improves air (and thus oxygen) circulation all the way around the firelog, improving the burning characteristics, and reduces the material that ultimately becomes a smoldering core, all without any special additives to the cellulosic material or to the binder. For example, a 6 lb. firelog in accordance with the invention burns for about 3 hours to 3-1/2 hours with a consistently medium-high flame, and very little by way of core material remains on the grate soon after the flame goes out, thus achieving a significant reduction in the total amount of CO produced. Such an improvement may be realized with firelogs of various sizes and weights.

Accordingly, it is an overall object of the invention to provide a novel and improved artificial or synthetic firelog that is environmentally friendly and environmentally sensitive.

It is another object of the invention to provide a novel firelog that emits a significantly reduced amount of total carbon monoxide during its combustion in comparison to a conventional firelog.

A further object of the invention is to provide a novel firelog configured to achieve simultaneously a significant reduction in the total carbon monoxide produced during its combustion and an improvement in burning characteristics.

It is still another object of the invention to provide a novel firelog configured so as to reduce the amount of material that will contribute to the smoldering core after the flame goes out.

It is a further object of the invention to provide a novel firelog configured so as to enable accumulation of combustible gases and improve air circulation all the way around the firelog during its combustion.

Another object of the invention is to provide a novel firelog without special additives either to the fiber, that is, cellulosic material, or to the binder, which achieves the foregoing objects in a simple, inexpensive, efficient, and elegant manner.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects, features and advantages of the invention will become apparent from the detailed description of the preferred embodiments, below, when read in conjunction with the accompanying drawings in which: Fig. 1 is a perspective view of an artificial firelog in accordance with a first embodiment of the invention, including in the bottom support surface a longitudinally extending groove defined by parallel side walls and a concave or arched top wall; Fig. 2 is a transverse cross section view of the artificial firelog of Fig. 1, the firelog being shown supported by a fireplace grate; Fig. 3 is a longitudinal cross section view of the artificial firelog in accordance with the first embodiment, as seen along the line 3-3 in Fig. 2;

Fig. 4 is a transverse cross section view of the artificial firelog of the first embodiment, illustrating the principal dimensions thereof; Fig. 5 is a transverse cross section view of an artificial firelog in accordance with a second embodiment of the invention characterized by a longitudinally extending groove of rectangular cross section formed in the bottom face thereof; Fig. 6 is a transverse cross section view of an artificial firelog in accordance with a third embodiment of the invention including a groove having an inverted V- shaped cross section; and Fig. 7 is a transverse cross section view of a fourth embodiment of the invention including a groove of trapezoidal cross section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to Figs. 1-3, there is shown an artificial firelog 10 in accordance with a first embodiment comprising an elongated body 12 composed of a mixture of cellulosic particles and combustible binder. The firelog 10 rests on a conventional grate 14 elevating the firelog and spacing it from a fireplace floor 16.

As is well known in the art, the cellulosic material may be sawdust or a mixture of sawdust with other combustible materials of varying proportion. The binder may consist of a suitable blend of waxes either alone or in combination with other combustible materials. Since the invention relates to the geometry of the firelog body 12, it will be understood that the composition thereof does not by itself form a part of the invention and that any artificial firelog composition and fabrication process used in the manufacture of such firelogs may be utilized to form a firelog in accordance with the invention.

To facilitate the description of the firelog of the present invention, the elongated body 12 of the firelog 10 may be visualized as extending along a longitudinal axis 18 and, as viewed along the end thereof, as including vertical and horizontal axes 20 and 22, respectively, that are mutually perpendicular to each other and the longitudinal axis 18. The elongated body 12 of the firelog has

opposed, parallel end faces 24 and, in a preferred form, a cross section transverse to the longitudinal axis whose configuration is uniform along substantially the entire length of the body 12. Thus, in accordance with the example of Figs. 1-3, the elongated firelog body 12 has parallel, planar top and bottom faces 26 and 28, respectively, and opposed sides 30 that are convex, that is, curved outwardly relatively to the longitudinal axis 18. Further, in the example of Figs. 1-3, the cross sectional configuration of the elongated firelog body is symmetrical about the longitudinal, vertical and horizontal axes, thus conforming to a cross sectional shape that is presently in common use. Also, as is known in the art, the firelog body 12 may have small longitudinally extending grooves or slots (not shown) in the lower rear corner of the firelog or the side and/or top faces thereof to improve ignition, burning performance and to control weight. Further, as illustrated in Figs.

2 and 3, the firelog body 12 will typically be fully enclosed within a conventional flammable wrapper 32 loosely disposed about the firelog body for initiating ignition of the firelog.

Firelog bodies incorporating the present invention may have outer cross sectional configurations different than that specifically shown in Figs. 1-3, including, for example, square or rectangular (with or without rounded edges), circular, polygonal, oval, pie-shaped, triangular, and so forth. All of these cross sectional shapes are well known in the art.

In accordance with a preferred embodiment of the invention, and irrespective of the specific overall cross sectional configuration of the firelog body 12, the flat bottom face 28 of the elongated body 12 comprises a firelog-supporting surface having formed therein a longitudinal groove 34 extending the entire length of the firelog body. This groove could be at the center or slightly offset to provide strength and integrity to the firelog, especially to accommodate other grooves placed elsewhere on the firelog for other purposes. In accordance with the present invention, the longitudinally extending groove 34 in the bottom face 28 of the firelog substantially reduces the total amount of carbon monoxide generated, helps

accumulate combustible gases, provides air circulation all the way around the firelog and simultaneously improves the burning characteristics, all without any special additives in the cellulosic material or in the binder. As shown in Figs. 2 and 3, during use of the firelog 10, the firelog is placed on the grate 14 with the bottom surface 28 face down resting on the grate.

Fig. 4 shows the dimensions of the firelog of the first embodiment. By way of example and not limitation, the overall height, H, of the firelog body may be about 3.625 inches and the overall width, W, may be about 3.933 inches. The groove 34 is defined by spaced-apart, parallel, vertical side walls 36 equidistant from the vertical axis 20, and an arched or concave top wall 38. The vertical side walls 36 each have a height, H, of about 5/16 inch. By way of specific example, the groove width, Wg, that is, the distance between the vertical side walls 36, is about 1 inch and the height, Hg, of the groove 34 measured at the highest point of the groove along the central vertical axis 20 is about 19/32 inch. The arched top wall 38 may comprise an arc of a circle of radius 19/32 inch centered on the intersection of the plane of the bottom face 28 and the vertical axis 20.

The specific cross sectional configuration of the longitudinally extending groove formed in the bottom face of the firelog body 12 is not critical as long as the groove extends lengthwise and adequate room for unobstructed air and combustible gas circulation.

Figs. 5 through 7 show second, third and fourth embodiments, respectively, of the firelog of the present invention. Although not limited thereto, each of these embodiments has an outer configuration and dimensions identical to that of the first embodiment as illustrated in Fig. 4.

The embodiment of Fig. 5 comprises a flammable body 50 including a bottom, planar face 52 having a longitudinally extending groove 54 of rectangular transverse cross section formed therein. The rectangular groove 54 is disposed symmetrically about a central, vertical axis 56, and is defined by parallel, vertical

side walls 58 spaced equidistant from the vertical axis, and a top, planar wall 60 parallel to a horizontal axis 62.

The third embodiment (Fig. 6) of the firelog in accordance with the invention includes a body 70 defining a bottom, planar face 72 having formed therein a groove 74 having an inverted V shape in'transverse cross section. The groove 74, which is preferably formed symmetrically about a vertical axis 76, includes symmetrically inclined sidewalls 78 intersecting at an apex 80.

The fourth embodiment of the invention, shown in Fig. 7, comprises a firelog including a flammable body 90 with a bottom planar face 92 having formed therein a groove 94 of trapezoidal cross section symmetrically disposed about a central vertical axis 96. The groove is defined by inwardly sloping sidewalls 98 and a top wall 100 lying in a plane parallel to the plane of the bottom face 92 of the firelog body.

A sample of each of the four grooved firelog embodiments described above in connection with Figs. 1-4,5,6 and 7, along with a reference firelog having no groove, was placed bottom face down on the grate of a Majestic MBU-36, a standard, residential, zero-clearance fireplace and ignited. The samples were burned under substantially the same burning conditions. The fireplace is mounted on a platform scale to monitor the weight loss continuously during the burn. The firelogs are prepared per manufacturer's instructions and placed on a multi-pronged basket-type grate with angled vertical extensions, with space between them not to exceed 4-inches to provide adequate support. A dilution tunnel is provided per the EPA method 5G specifications. Carbon monoxide samples are extracted from the dilution tunnel through a gas sampling port. The sample is then routed through a filter, a sample pump, and a pressure regulator to a non-dispersive type infrared CO analyzer for continuous monitoring. The data collected was analyzed by the standard EPA method 5G methodology.

The results of the test burns for the various firelogs described above were as follows: Test Firelog % Reduction t-Total CL2 Reference firelog (no groove) 0 Firelog with rounded or arch top 18.9 groove Firelog-with rectangular groove19. 0 Firelog with V-shaped grooye 21. 4 Firelog with trapezoidal groove 12. 2

1. Percent reduction in the total carbon monoxide was calculated based on a comparison with a standard firelog without the groove.

2. Carbon monoxide as continuously measured with a non-dispersive infrared analyzer, data collected by a data logger, processed, plotted and calculated by LabTech Notebook software, in a modified version of the Standard EPA Method 5G, per"Federal Register, 40 CFR Part 60, February 26, 1988"test.

It will thus be seen that grooved firelogs in accordance with the invention resulted in significant reductions in total CO emissions in comparison with an identical firelog without a groove.

While the present invention has been described with reference to particular illustrative embodiments, the invention is not intended to be restricted to those embodiments but only by the appended claims. It will be appreciated that those skilled in the art can change or modify the described embodiments, or substitute equivalents for the various elements described and shown, without departing from the scope and spirit of the invention.