FIRE GRATE WITH HOT COAL AND ASH

Abstract

A fire grate assembly for burning solid fuel is discussed in the present disclosure. In one exemplary embodiment, a metal frame has a grate for supporting solid fuel during combustion and, below the grate, a hot coal and ash filter having an undulating upper surface for separating hot coals of different sizes, filtering out ash, and allowing vertical airflow through the hot coals. The assembly may also have a cage extending generally upwards from the solid fuel supporting grate perimeter to help retain the solid fuel thereon and may also have projections extending from the frame to support the hot coal and ash filter above a surface.

Claims

1. A hot coal managing and ash filtering fire grate assembly comprising: a metal frame defining an open horizontal cross sectional area; and, a solid fuel supporting grate affixed to an upper portion of the metal frame and extending generally horizontal, the solid fuel supporting grate having a plurality of spaced cross members defining vertical through openings that in use allow vertical passage of hot coals; and, a coal and ash filter affixed to a lower portion of the metal frame at a spaced distance below the solid fuel supporting grate of about 2 inches to about 8 inches, measured from the top surface of the grate to the top surface of the filter, for receiving on an upper surface thereof hot coals passed downward from the solid fuel supporting grate, the coal and ash filter having an undulating upper surface that defines progressively smaller horizontal passageways from the upper surface to a lower surface thereof so that received hot coals progress vertically downward on the coal and ash filter as they burn and reduce in size, thereby creating vertical spacing between smaller and larger hot coals and allowing ash to pass completely through the filter.

2. The hot coal managing and ash filtering fire grate assembly of claim 1, wherein the undulating surface is formed by a plurality of adjacent support struts defining the progressively smaller horizontal passageways from the upper surface to the lower surface thereof.

3. The hot coal managing and ash filtering fire grate assembly of claim 1, wherein the undulating surface is formed by sheet metal in a zig-zag arrangement creating peaks and valleys in at least one horizontal direction defining the progressively smaller horizontal passageways from the upper surface to the lower surface thereof.

4. The hot coal managing and ash filtering grate assembly of claim 1, wherein the assembly further comprises vertically downward projections that support the coal and ash filter above a surface.

5. The hot coal managing and ash filtering grate assembly of claim 1, wherein the assembly further comprises support members extending beyond the horizontal cross sectional area to engage an edge of a fire pit or fire ring and support the coal and ash filter above a surface.

6. The hot coal managing and ash filtering grate assembly of claim 1, wherein the solid fuel supporting grate includes a plurality of spaced crossmembers defining vertical through openings with horizontal spacing of about 3 inches to about 6 inches that in use allow vertical passage of hot coals.

7. The hot coal managing and ash filtering grate assembly of claim 6, wherein the solid fuel supporting grate includes a first plurality of spaced crossmembers with horizontal spacing of about 3 inches to about 6 inches and a second plurality of spaced crossmembers, generally perpendicular to the first plurality, with horizontal spacing of about 3 inches to about 6 inches defining a grid of vertical through openings that in use allow vertical passage of hot coals.

8. The hot coal managing and ash filtering grate assembly of claim 1, wherein the coal and ash filter passageways at the lower surface allow passage of hot coals having horizontal dimensions of less than about 0.25 inches to less than about 0.75 inches.

9. The hot coal managing and ash filtering grate assembly of claim 1, wherein the coal and ash filter is affixed to a lower portion of the metal frame at a spaced distance below the solid fuel supporting grate of about 3 inches to about 5 inches measured from the top surface of the grate to the top surface of the filter.

10. The hot coal managing and ash filtering fire grate assembly of claim 3, wherein the valleys of the coal and ash filter are substantially open passageways to minimize the build-up of ash on the surfaces thereof.

11. The hot coal managing and ash filtering fire grate assembly of claim 10, wherein the valleys of the coal and ash filter are greater than 90% open passageways to minimize the build-up of ash on the surfaces thereof.

12. The hot coal managing and ash filtering fire grate assembly of claim 3, wherein the horizontal distance between adjacent peaks is between about 1 inch and about 4 inches and the vertical distance between peaks and valleys is between about 1.5 inches and about 6 inches.

13. The hot coal managing and ash filtering fire grate assembly of claim 12, wherein the horizontal distance between adjacent peaks is between about 2 inches and about 3 inches and the vertical distance between peaks and valleys is between about 2.5 inches and about 4 inches.

14. The hot coal managing and ash filtering fire grate assembly of claim 3, wherein the sheet metal is perforated, creating openings with a minor dimension between 0.25 and 0.75 inches and an open area between 10 and 70 percent.

15. A hot coal managing and ash filtering fire grate assembly comprising: a metal frame defining an open horizontal cross sectional area; and, a solid fuel supporting grate affixed to an upper portion of the metal frame and extending generally horizontal, the solid fuel supporting grate having a plurality of spaced cross members defining vertical through openings that in use allow vertical passage of hot coals; and, a coal and ash filter affixed to a lower portion of the metal frame at a spaced distance below the solid fuel supporting grate of about 2 inches to about 8 inches measured from the top surface of the grate to the top surface of the filter for receiving on an upper surface thereof hot coals passed downward from the solid fuel supporting grate, the coal and ash filter having an undulating upper surface that defines progressively smaller horizontal passageways from the upper surface to a lower surface thereof so that received hot coals progress vertically downward on the coal and ash filter as they burn and reduce in size, thereby creating vertical spacing between smaller and larger hot coals and allowing ash to pass completely through the filter; and, a cage extending generally upwards from the solid fuel supporting grate perimeter to help retain the solid fuel thereon.

16. The hot coal managing and ash filtering fire grate assembly of claim 15, wherein the cage extends generally upwards and outwards from the solid fuel supporting grate perimeter in a funnel shape which guides solid fuel towards the center of the grate as the solid fuel below it breaks up into hot coals and passes through the grate.

17. The hot coal managing and ash filtering fire grate assembly of claim 15, wherein the cage is made from a metal mesh or perforated sheet metal having an open area of more than about 50 percent.

18. The hot coal managing and ash filtering fire grate assembly of claim 15, wherein the cage comprises an array of generally vertical metal members with a profile width of about 0.04 inches to about 0.50 inches on the side that faces the center of the grate to minimize blockage of radiant heat from the burning solid fuel and hot coals.

19. A hot coal managing and ash filtering fire grate assembly comprising: a metal frame defining an open horizontal cross sectional area; and, a solid fuel supporting grate affixed to an upper portion of the metal frame and extending generally horizontal, the solid fuel supporting grate having a plurality of spaced cross members defining vertical through openings that in use allow vertical passage of hot coals; and, a coal and ash filter affixed to a lower portion of the metal frame at a spaced distance below the solid fuel supporting grate of about 2 inches to about 8 inches measured from the top surface of the grate to the top surface of the filter for receiving on an upper surface thereof hot coals passed downward from the solid fuel supporting grate; and, support members extending beyond the horizontal cross sectional area to engage an edge of a fire pit or fire ring and support the coal and ash filter above a surface.

20. The hot coal managing and ash filtering fire grate assembly of claim 19, further comprising a cage extending generally upwards from the solid fuel supporting grate perimeter to help retain the solid fuel thereon.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which:

[0028] FIG. 1 is a perspective view of a fire grate assembly of the present disclosure.

[0029] FIG. 2 is a perspective section view of the fire grate assembly depicted in FIG. 1

[0030] FIG. 3A is a perspective view of a coal and ash filter depicted in FIG. 2.

[0031] FIG. 3B is a perspective view of a filter element from the coal and ash filter of FIG. 3A

[0032] FIG. 4A is a plan view of a cross-section of the fire grate assembly of FIG. 1 depicting the combustion process within the fire grate assembly.

[0033] FIG. 4B is a detail view of FIG. 4A depicting the combustion process within the coal and ash filter.

[0034] FIG. 5 is a perspective view of an alternative fire grate assembly incorporating a funnel-shaped frame.

[0035] FIG. 6A is a perspective view of an alternative embodiment of the disclosed fire grate assembly in which the frame extends to the ground to support the assembly.

[0036] FIG. 6B is a perspective section view of the embodiment depicted in FIG. 6A

[0037] FIG. 7 is a perspective view of an alternative embodiment of the disclosed fire grate assembly in which there are louvered openings at the base of the frame.

[0038] FIG. 8 is a perspective view of an alternative embodiment of the disclosed fire grate assembly in which the cross-sectional shape of the frame is rectangular.

[0039] FIG. 9 is a perspective view of the disclosed fire grate assembly in which a receptacle is located below the coal and ash filter to collect ashes after they have fallen through the filter.

[0040] FIG. 10 is a perspective view of an alternative embodiment of the disclosed fire grate assembly in which the frame has legs extending from it to the ground for supporting the assembly.

[0041] FIG. 11 is a perspective view of an alternative embodiment of the disclosed fire grate assembly in which the assembly is supported by members extending outward from the frame, such that the fire grate assembly is suspended over a traditional fire pit or fire ring.

DETAILED DESCRIPTION

[0042] For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification.

[0043] All numeric values are herein assumed to be modified by the term about, whether or not explicitly indicated. The term about generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (e.g., having the same function or result). As used herein, the use of the term about with numerical values includes numbers that are rounded to the nearest significant figure.

[0044] The recitation of numerical ranges by endpoints includes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0045] As used in this specification and the appended claims, the singular forms a, an, and the include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term or is generally employed in its sense including and/or unless the content clearly dictates otherwise.

[0046] It is noted that references in the specification to an embodiment, some embodiments, other embodiments, etc., indicate that the embodiment described may include one or more particular features, structures, and/or characteristics. However, such recitations do not necessarily mean that all embodiments include the particular features, structures, and/or characteristics. Additionally, when particular features, structures, and/or characteristics are described in connection with one embodiment, it should be understood that such features, structures, and/or characteristics may also be used in connection with other embodiments whether or not explicitly described unless clearly stated to the contrary.

[0047] The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the disclosure.

[0048] FIG. 1 is a perspective view of an exemplary fire grate assembly 10. The fire grate assembly 10 may generally comprise a frame 11 with upper and lower openings. The frame 11 has, near its upper opening, a grate 12 for supporting solid fuel such as firewood 13. The frame 11 and grate 12 may generally be formed from metal and form a relatively rigid structure when attached to one another. It is noted that the frame 11 may take any shape with a generally vertical internal passageway. The grate 12 is positioned within the upper opening of the frame 11.

[0049] In the example of FIG. 1, the frame 11 is a tube of cylindrical shape with support members 14 that extend from the frame 11 to a cylindrical metal stand 15. The support members 14 may be constructed of metal, creating generally rigid members. In the example of FIG. 1, a cage 16 extends generally upwards from the perimeter of the grate 12. The cage 16 may be constructed from metal and forms a structure to retain the firewood 13 on the grate 12, preventing the firewood 13 from falling or rolling off the sides of the grate 12. Such a feature is useful when there are multiple pieces of firewood 13 stacked on one another upon the grate 12.

[0050] FIG. 2 is a perspective section view of the exemplary fire grate assembly 10 depicted in FIG. 1. The grate 12 is positioned towards the upper opening of the frame 11. A hot coal and ash managing filter 17 is positioned below the grate 12. In the example of FIG. 2, the filter 17 is also located within the frame 11. The cage 16 is composed of an array of vertical members 51 which may be connected together by a peripheral member 52 which may attach to each member in the array, giving the structure greater rigidity. Additionally, the vertical members 51 may have a cross-section with a narrow profile 53 in one direction and a wide profile 54 in the perpendicular direction. The narrow profile 53 could be in the range of about 0.04 inches to about 0.50 inches. In other instances, the narrow profile 53 could be in the range of about 0.06 inches to about 0.25 inches. The wide profile 54, perpendicular to the narrow profile 53, could have a width in the range of about 0.75 inches to about 3.0 inches. In other instances, the wide profile 54 could be in the range of about 1.0 inches to about 1.75 inches. Ideally, the narrow profile 53 of the vertical members 16 are generally facing the center of the fire grate assembly 10, such that the vertical members 16 block a minimal amount of light and radiant heat being projected outward from the combustion towards people sitting around the fire grate assembly 10, while still functioning to contain the firewood 13 on the grate 12.

[0051] FIG. 3A depicts a perspective view of this exemplary coal and ash filter 17. In this embodiment, the filter 17 is composed of a series of formed sheet metal members 18 which have inverted, V-shaped cross sections.

[0052] FIG. 3B is a perspective view of one of these filter members 18 which have openings 19 in the sheet metal to improve the flow of air upwards and the filtering of ashes downward. The size, quantity, and spacing of the openings 19 contributes to the open area of the filter 17. The open area is generally proportional to the rate of air flow through the filter 17. Greater air flow can increase the efficiency of the combustion, resulting in a hotter, faster burning fire. Conversely, reduced air flow will slow the combustion, resulting in a less hot, slower burning fire. The filter members 18 may have an open area in the range of about 10% to about 70%. In other instances, the filter members 18 may have an open area in the range of about 30% to about 50%. The openings 19 in the filter members 18 could have nearly any shape, as their function is to limit the size of ashes which can fall downward through the filter while allowing air to flow upwards through the hot coals. The smallest width of the openings 19, known as the minor dimension 20, could be in the range of about 0.25 inches to about 0.75 inches. In other instances, the minor dimension 20 could be in the range of about 0.37 inches to about 0.63 inches.

[0053] FIG. 4A is a cross section view of an exemplary fire grate assembly 10. In this embodiment, the frame 11 serves as the central structural element, onto which the other components and sub-assemblies of the fire grate assembly 10 attach. The grate 12 is attached at the upper portion of the frame 11 and supports the solid fuel which, in the present embodiment, is firewood 13. As the firewood 13 combusts, flames 21 are produced and are highly visible through the cage 16 around the periphery of the grate 12. The coal and ash filter 17 is positioned below the grate 12. As the firewood 13 breaks apart during combustion, coals 22 of different sizes fall through the grate 12 and come to rest on the filter 17.

[0054] The construction of the filter 17 to support coals 22 at different vertical positions is important to maintaining consistent airflow through the coals 22. If the filter 17 were relatively planar, like a single horizontal, perforated steel sheet or a grille, it would support all the coals 22 at one level until they burned down to a small enough size to fall through the openings. If a relatively planar filter design had small openings or narrow spacing between grille members, both large and small coals 22 wound pile onto and next to each other, blocking off the openings in the filter and reducing the size and number of air gaps between the coals 22. It is desirable to keep the coals 22 in general proximity to one another, but to create air gaps between the coals through which heated air can travel upwards, providing oxygen for combustion of the coals 22 and the firewood 13. If a relatively planar filter had large openings or wide spacing between grille members, the hot coals 22 would fall through the openings before they've finished burning down, moving them out of proximity to the firewood 13 on the grate 12.

[0055] It is also desirable for ash 25 (coals which have completed combustion fully or nearly fully) to drop down through the filter 17, so that they do not prohibit the flow of heated air through the coals 22.

[0056] In the present embodiment, the frame 11 is supported on and within a cylindrical metal stand 15. The metal stand 15 has a larger cross section than the frame 11 creating an air gap between the outside of the frame and the inside of the metal stand's wall. Fresh air can be drawn through this air gap and into the bottom opening of the frame 11 by the rising of hot air in the frame 11. In FIG. 4A, the flow of fresh air through this gap is depicted by curved arrows 23 and the upward flow of heated air passing through the filter and the grate is depicted by the vertical arrows 24.

[0057] FIG. 4B depicts a detail view of the cross-sectional view in FIG. 4A, detailing the area around the coal and ash filter 17 and the grate 12. The grate 12 may be made of steel bars or rods spaced apart such that they will support logs but allow large coals 22 to drop through to the filter 17. Spacing between the members of the grate 26 could be in the range of about 3 inches to about 6 inches. The grate 12 may also be composed of steel bars or rods configured in perpendicular arrays to create a grid pattern when viewed from above.

[0058] In the exemplary fire grate of FIG. 4B, the filter 17 is composed of a series of inverted V-shaped, perforated steel members 18. The vertical grate-to-filter distance 27 from the top surface of the grate 12 to the top surface of the filter 17 is important, as this grate-to-filter distance 27 controls the proximity of the hot coals 22 on the filter 17 to the firewood 13 combusting on the grate 12. Close proximity of the coals 22 to the firewood 13 helps drive the combustion of the firewood 13. An effective grate-to-filter distance 27 may be in the range of about 2 inches to about 8 inches (50 to 200 mm). In other instances, the grate-to-filter distance 27 may be in the range of about 3 inches to about 5 inches (75 to 125 mm).

[0059] As firewood 13 burns up on the grate 12, coals 22 can fall through the grate 12 and rest on the filter 17. Some coals 22 will have a coal width 28 larger than the horizontal peak-to-peak distance 29 between adjacent filter members 18. In these cases, the larger coals 22 will rest on top of the filter 17 in close proximity to the firewood 13 burning on the grate 12. As the large coals 22 continue to burn, they may break into smaller pieces. When the coals 22 have a smaller coal width 28 than the horizontal peak-to-peak distance 29, they can fall into the valleys between the filter members 18. Due to their inverted V-shape, the horizontal space between adjacent filter members 18 decreases in the downward direction. The vertical peak-to-valley distance 30 may be in a range of about 1.5 inches to about 6 inches. In other instances, the vertical peak-to-valley distance 30 may be in a range of about 2.5 inches to about 4 inches. As coals 22 continue to burn up and become even smaller, they move downward within the filter 17. This change in vertical resting position of the coals 22 helps create separation between them that leaves more of their surface area exposed to the flow of air 24 moving through the filter 17. Once the coals 22 have burned to ash 25, burned down smaller than the openings 19 in the filter members 18, or burned down smaller than the filter passageways 31 at the lower surface of the filter 17, they fall through, clearing the way for more coals to progress downward through the filter 17.

[0060] FIG. 5 is a perspective view of an alternative embodiment of the disclosed fire grate assembly 100. While similar to the embodiment in FIG. 1, this embodiment has a frame 101 whose cross-sectional area changes in size. Specifically, the frame 101 of the exemplary fire grate assembly in FIG. 5 has a generally conical shape to it. It is noted that the frame 101 could conceivably have various cross-sectional shapes and sizes including, but not limited to: circular, polygonal, or oval. A conical cross section could be beneficial for funneling coals at the periphery of the fire grate assembly 100 towards the center. A conical shaped frame 101 could also serve to accelerate or decelerate the flow of air traveling upwards through the frame 101, thus promoting a faster or slower rate of combustion, as desired.

[0061] FIG. 6A is a perspective view of an alternative embodiment of the disclosed fire grate assembly 150. In this embodiment, the frame 151 has a four-sided polygonal cross-section and extends to the ground. In order to create a vertical air passageway through the frame 151, openings 152 on the lower sides of the frame 151 allow air to enter before moving upwards through the frame 151. In the present embodiment, the frame 151 is tapered, with a larger cross-sectional area at its bottom than at its top. This shape may be used to give the fire grate assembly 150 greater stability by being wider at its base. This shape can also serve to accelerate the air flowing vertically through the frame 151. The grate 153 is composed of individual metal bars or rods extending across the top of the frame 151. The cage 154 around the periphery of the grate is constructed from sheet metal with perforations or openings cut into them. Of course, the perforated sheet metal could be replaced with expanded metal, wire mesh, or similar materials.

[0062] FIG. 6B is a perspective section view of an exemplary fire grate assembly 150. This view shows the grate 153 and coal and ash filter 155 within the frame 151. The members comprising the grate 153 span across the upper opening of the frame 151. The members of the grate 153 could be welded into place or could be removable for cleaning or replacement. In the present embodiment, the hot coal and ash filter 155, is composed of two horizontal arrays of crossmembers spaced out from one another: an upper array 156 and a lower array 157. The upper array 156 has more distance between the crossmembers than the lower array 157. Large coals that fall through the grate 153 will rest on the upper array 156 of crossmembers. As coals continue to burn up and become even smaller, they can fall through the upper array 156 and come to rest on the lower array 157. This change in vertical resting position of the coals helps create separation between them that leaves more of their surface area exposed to the flow of air moving through the filter 153. Once the coals are smaller than the distance between crossmembers in the lower array 157, they can fall through, clearing the way for more coals to progress downward through the filter 153.

[0063] FIG. 7 is a perspective view of an exemplary fire grate assembly 200. The fire grate assembly 200 has a frame 201 with upper and lower openings. The frame 201 has, near its upper opening, a grate 202 for supporting solid fuel and a cage 203 to retain the solid fuel on the grate 202. At the upper opening of the frame 201, sloping sheet metal members 204 guide hot coals into the frame 201. At the base of the frame 201, several arrays of louvered openings 205 allow air to enter the lower portion of the frame 201.

[0064] FIG. 8 is a perspective view of an exemplary fire grate assembly 250. The fire grate assembly 250 has a frame 251 with upper and lower openings. In the present embodiment, the cross-sectional shape of the frame 251 is rectangular. The frame 251 has, near its upper opening, a grate 252 for supporting solid fuel and a cage 253 to retain the solid fuel on the grate 252. In the present embodiment, the members of the grate 252 are integral with the members of the cage 253.

[0065] FIG. 9 is a perspective view of an exemplary fire grate assembly 300. This embodiment of a fire grate assembly 300 is similar in construction to the fire grate assembly depicted in FIG. 1, except that rather than having support members to support the frame on top of a cylindrical metal stand, the frame 301 of the present example is supported by legs 302 That extend generally downward from the frame 301.

[0066] FIG. 10 is a perspective view of the fire grate assembly 300 of FIG. 9 with a receptacle 303 located below the frame 301 to collect ashes or small embers after they have fallen through the filter. The receptacle 303 could be resting on the ground below the fire grate assembly 300, as shown, or it could be supported within or below the frame 301 anywhere beneath the filter.

[0067] FIG. 11 is a perspective view of an exemplary fire grate assembly 400. The present embodiment of a fire grate assembly 400 is similar in construction to the fire grate assembly depicted in FIG. 1. The frame 401 of the present example is supported by members 402 extending outward from the frame such that the fire grate assembly 400 is supported by and suspended over an existing fire pit or fire ring 403.