GB2535824A

GB2535824A - Fuel burning stove

Info

Publication number: GB2535824A
Application number: GB1519504.3A
Authority: GB
Inventors: Staniland Burgis John
Original assignee: ARADA Ltd
Current assignee: ARADA Ltd
Priority date: 2012-04-12
Filing date: 2013-04-12
Publication date: 2016-08-31
Also published as: GB201519503D0; GB2534642A; GB2503319A; GB201206454D0; GB201519504D0; GB2503319B; GB201306699D0

Abstract

A fuel burning stove comprises a grate for supporting fuel to be burned, the grate comprising a set of separate grate bars 5 extending approximately parallel to one another from a first side of the grate to a second side opposite the first side with spaces between adjacent bars. The grate bars 5 are supported at their ends with the tops of their ends at approximately the same level, that level defining a first horizontal plane, and the tops of middle portions 8 of the grate bars are lower than the first horizontal plane thereby defining a depressed middle portion of the grate.

Description

Fuel burning stove This invention relates to a fuel burning stove. The invention is especially concerned with stoves for burning 5 wood.

An important factor in the design of a fuel burning stove concerns the retention of an appropriate amount of ash on the grate. It is desirable, when burning wood, to have a bed of ash retained on the grate but the thickness of that bed should be controlled. It is therefore also desirable that the ash is able to pass through the grate into an ash pan below.

It is an object of the present invention to provide a fuel burning stove that is improved over certain existing 15 stoves in one or more respects.

According to a first aspect of the invention there is provided a fuel burning stove comprising a grate for supporting fuel to be burned, the grate comprising a set of separate grate bars extending approximately parallel to one another from a first side of the grate to a second side opposite the first side with spaces between adjacent bars, wherein each grate bar is of substantially the same design having first and second ends, the first end of each grate bar being placed next to the second end of an adjacent grate bar, thereby defining a first group of grate bars having their first ends at the first side of the grate and their second ends at the second side of the grate, and a -2 -second group of grate bars alternating with the first group of bars and having their first ends at the second side of the grate and their second ends at the first side of the grate.

By providing a grate comprising such grate bars, the production and repair of a stove is greatly facilitated. By providing an arrangement of grate bars where all the bars are the same but adjacent bars are disposed in opposite orientations, it is possible to provide adjacent grate bars with different characteristics even though the bars of exactly the same design. This allows various designs to be achieved with special advantageous features, as described below.

Where reference is made to first and second "sides" of the grate, it should be understood that whilst in an embodiment of the invention described below the "sides" are at the front and rear of the grate, it is also within the scope of the invention for the sides to be represented by the lateral edges of the grate.

Preferably the stove further includes a riddling mechanism for moving one grate bar relative to an adjacent grate bar. More preferably, the riddling mechanism moves the first group of grate bars relative to the second group of grate bars. Such movement can disturb a bed of ash supported on the grate bars and cause ash to fall between bars into an ash pan, reducing the depth of the bed of ash on the grate.

Whilst it is within the scope of the invention for the movement of the bars to have a substantial component perpendicular to the longitudinal axes of the grate bars, it will generally be preferred that a major component of the movement is in a direction approximately parallel to the longitudinal axes of the grate bars.

The riddling mechanism preferably includes the drive member for engaging the first ends of the first group of grate bars and the second ends of the second group of grate bars. It is also possible for the same drive member or another drive member to engage the second ends of the first group of grate bars and the first ends of the second group of grate bars, but this is not a feature of the embodiment described below and will not generally be necessary.

The drive member is preferably an elongate plate with a longitudinal edge of the plate being of generally castellated form, with projecting portions of the castellated edge engaging ends of the first group of grate bars and recessed portions of the castellated edge engaging ends of the second group of grate bars.

The drive member is preferably pivotally mounted. Pivotal movement of the drive member is preferably arranged to drive the first group of grate bars in one direction and the second group of grate bars in a second, opposite, direction. It should be understood however, that another possibility would be for the drive member only to drive one group of grate bars or even for the drive member to drive -4 -both groups of grate bars in the same direction, but at different speeds and/or amplitudes. The projecting portions of the drive member are preferably disposed on the opposite side of its axis of pivoting to the recessed portions of the drive member. In that way pivotal movement of the drive member results in movement of the first group of grate bars in an opposite direction to the movement of the second group of grate bars.

The grate bars are preferably supported at their ends with the tops of their ends at approximately the same level, that level defining a first horizontal plane, and the tops of middle portions of the grate bars are preferably lower than the first horizontal plane thereby defining a depressed middle portion of the grate. In an embodiment of the invention described below, the first ends of the grate bars are of different depths from the second ends of the grate bars, thereby enabling the tops of the grate bars to be at the same level even though bottoms of the bars are engaged by the castellated edge of the drive member. The depressed middle portion of the grate bar may be of curved shape, being most depressed in a central region.

By providing a depressed middle portion of the grate, it becomes possible to arrange that as a fire burns fuel is fed towards the middle portion of the grate, thereby facilitating complete combustion of the fuel. -5 -

Preferably the depressed middle portion of the grate is more than 30 mm, and more preferably more than 35 mm, below the first horizontal plane. In that way a deep grate can be provided which is well suited for burning of wood fuel and allowing the build up on the grate of an ash bed. Preferably the depressed middle portion of the grate would be not more than 50 mm below the first horizontal plane.

Preferably each grate bar generally comprises first and second raised ends, a depressed middle portion and inclined portions extending between the first and second ends and the depressed middle portion. The inclined portions may merge smoothly with the depressed middle portion. Where reference is made in the specification to "ends" of grate bars, it should be understood that the term refers not just to an end face of the grate bar but to an end portion.

The grate bars are preferably wider at their ends and adjacent ends of adjacent bars are preferably immediately adjacent to one another. By having adjacent ends of adjacent bars in contact with one another or virtually in contact with one another the bars are automatically retained in position. At some position, however, the bars should be narrower to define spaces between bars for ash to pass through.

Each grate bar preferably generally comprises first and second raised ends, a depressed middle portion and inclined portions extending between the first and second -6 -ends and the depressed middle portion, and a part of the depressed middle portion is of reduced width, whereby gaps are formed towards the middle of the grate between adjacent bars.

The grate bars preferably have top faces provided with recesses for retaining pockets of ash when, in use fuel is burnt on the stove. The retained ash can tend to keep hot burning embers away from direct contact with a grate bar, thus prolonging the life of the grate bar.

The recesses may take a wide variety of forms.

Preferably the recesses comprise longitudinal grooves in the top faces of the grate bars. In an embodiment of the invention described below each grate bar is provided with one longitudinal groove. The recesses preferably comprise dimples in the top faces of the grate bars. The dimples on a grate bar may comprise a row of dimples extending along the bar. Other dimples of other sizes may also be provided. In an embodiment of the invention described below each grate bar is provided with a row of relatively small dimples and a larger dimple at each end of the row. In the particular embodiment described below, there are two rows of such dimples on each bar and there are three dimples in the row. The rows are on either side of a central longitudinal groove.

Some of the features described above as preferred features of the first aspect of the invention are themselves novel and inventive features that can be used in -7 -other forms of grate that are not in accordance with the first aspect of the invention.

Thus in a second aspect of the invention there is provided a fuel burning stove comprising a grate for supporting fuel to be burned, the grate comprising a set of separate grate bars extending approximately parallel to one another from a first side of the grate to a second side opposite the first side with spaces between adjacent bars, wherein the grate bars are supported at their ends with the tops of their ends at approximately the same level, that level defining a first horizontal plane, and the tops of middle portions of the grate bars are lower than the first horizontal plane thereby defining a depressed middle portion of the grate.

The stove according to the second aspect of the invention may incorporate any of the features described above with reference to the first aspect of the invention.

According to a third aspect of the invention there is provided a fuel burning stove comprising a grate for supporting fuel to be burned, the grate comprising a set of separate grate bars extending approximately parallel to one another from a first side of the grate to a second side opposite the first side with spaces between adjacent bars, wherein the grate bars have top faces provided with recesses for retaining pockets of ash when, in use, fuel is burnt on the stove. -8 -

The stove according to the third aspect of the invention may incorporate any of the features described above with reference to the stove of the first aspect of the invention.

According to a fourth aspect of the invention there is provided a fuel burning stove comprising a grate for supporting fuel to be burned, the grate comprising a set of separate grate bars extending approximately parallel to one another from a first side of the grate to a second side opposite the first side with spaces between adjacent bars, wherein each grate bar is of substantially the same design having first and second ends, and a riddling mechanism for moving one grate bar relative to an adjacent grate bar.

Whilst various aspects of the invention have been described above, it should be understood that, as already implied, features described in respect of one aspect of the invention may also be provided in another aspect. For example, a grate bar of the second aspect of the invention may comprise first and second raised ends, a depressed middle portion and inclined portions extending between the first and second ends and the depressed middle portion, and a part of the depressed middle portion may of reduced width. Also a grate bar according to the second aspect of the invention may be provided with recesses for accommodating pockets of ash. -9 -

By way of example embodiments of the invention will now be described with reference to the accompanying schematic drawings, of which: Fig. 1 is a perspective view from above of a grate assembly of a wood burning stove embodying the invention; Fig. 2 is a perspective view from below of a part of grate assembly shown in Fig. 1; Fig. 3A is a perspective view of a grate bar of the grate assembly of Figs.1 and 2; Fig. 3B is a plan view of the grate bar shown in Fig. 3A; Fig. 3C is a side view of the grate bar shown in Figs.3A and 3B; Fig. 4A is a perspective view of a modified grate bar that may be used in place of the grate bar of Figs. 3A to 30; Fig. 4B is a plan view of the grate bar shown in Fig. 4A; and Fig. 4C is a side view of the grate bar shown in Figs. 4A and 4B.

Referring first to Figs.1 and 2, there is shown a grate assembly for a wood burning stove. As will be understood, a complete stove will have a housing within which the grate assembly of Figs.1 and 2 is disposed. The nature of that housing is not of any particular relevance -10 -to the invention and is therefore not described further here.

The grate assembly of Figs.1 and 2 generally comprises side walls 1 and 2, a rear transverse supporting member 3 connected between the walls 1 and 2, and a front supporting member 4 mounted at the front of the side walls 1 and 2 in a manner that will be described further below. A plurality of grate bars 5 extend across the grate, supported on the supporting members 3 and 4.

Referring now also to Figs.3A to 3C, it should first be noted that all the grate bars 5 (in the particular example shown there 11 bars) are of the same design. The bars 5 appear at first sight from, for example, Fig. 1 to be of different designs because it can be seen that the front ends of the bars shown differ. That is explained, however, by the fact that the first ends 6 of each bar are of different design from their opposite second ends 7 and adjacent bars are placed on the supporting members 3 and 4 with 180° rotation of every other bar. Thus the grate can be regarded as comprising a first group of grate bars 5A having their first ends 6 supported on the front supporting member 4, and a second group of grate bars 5B alternating with the first group of grate bars 5A and having their second ends 7 supported on the front supporting member 4.

Each grate bar 5 generally comprises a first end 6, a second end 7, a depressed middle portion 8, and inclined portions 9 extending between the ends 6, 7 of the bar and the depressed middle portion 8. The tops of the ends 6, 7 are in a common horizontal plane which in this particular example is 40mm above the top of the middle portion 8 of the bar. The ends 6, 7 of the bar are each provided on their underside with a V-shaped recess 10. As can be seen most clearly in Fig. 3B, each bar 5 is of constant width along its length, apart from along a part of the depressed middle portion 8 where an elongate recess 11 is formed on each side of the bar. When the bars are placed on the supporting members 3 and 4, the recesses 11 of adjacent bars co-operate to define spaces between the bars through which, in use, ash can fall into an ash pan (not shown). In a particular example of the invention the spaces formed between the bars are of the order of 10 mm wide.

Each bar 5 is formed with a longitudinal groove 12 extending along the centre of the top of the bar along the inclined portions 9 and the depressed middle portion 8. In addition, the depressed middle portion 8 is provided with a row of three dimples 13 on either side of the groove 12, and larger dimples 14 at each end of each row of dimples 13.

The grate assembly includes a riddling mechanism for moving the first group of grate bars 5A relative to the second group of grate bars 5B. Referring especially to Fig. 2, the first supporting member 4 is generally in the form of an elongated plate having a castellated upper edge defining projecting portions 16 and recessed portions 17.

-12 -The projecting portions 16 engage in the V-shaped recesses 10 of the first ends 6 of the bars 5A whilst the recessed portions 17 engage in the V-shaped recesses 10 of the second ends 7 of the bars 5B.

The plate formed by supporting member 4 has end parts 4A and 4B which pass through openings in the tops of the side walls 1 and 2 respectively and mount the plate for pivoting movement about a longitudinal access of the plate. The end part 4B that passes through the opening in the top of the side wall 2 projects downwardly and is received in a recess 18 in an actuator bar 19. As shown in Figs.1 and 2, the actuator bar 19 has a front end 20 which passes through an opening in the housing (not shown) of the stove and receives an actuator knob (not shown) on it for control by a user. At the rear of the grate, the supporting member 3 is provided with a castellated top. As will be understood the castellations on the supporting members 3 and 4 have the effect of cancelling out the different depths of the ends 6 and 7 of the grate bars 5 so that, when the grate bars are supported on the members 3 and 4, the tops of the ends of the grate bars are at approximately the same level. In use of the stove, wood is placed on the grate bars 5. As the wood burns a bed of ash develops on the bars. Some ash is received in the dimples 13, 14 and the groove 12 of each grate bar 5, thereby protecting the bars from the heat of the burning wood. Without any movement of the bars there will be some ash that will fall through the -13 -spaces created by the recesses 11 but only a limited amount of ash will fall through and a bed of ash develops on the bars 5. This is desirable when burning wood. When the bed of ash has reached the maximum depth that provides for best operation, a user can reciprocate the actuator bar 19 causes the supporting member 4 to pivot in the openings in the side walls 1 and 2. The axis of pivoting of the member 4 is between the tops of the projecting portions 16 and the tops of the recessed portions 17; consequently the pivoting of the supporting member 4 causes the group of grate bars 5A to move in one direction (eg. forwards) while the group of grate bars 5B moves in the opposite direction (eg. backwards). That relative movement disturbs the bed of ash and causes ash to fall through the spaces defined by the recesses 11.

Thus it will be seen that it is very simple for a user to control the depth of the bed of ash on the grate bars 5. In the event that a grate bar becomes damaged, it is an extremely simple matter to replace the bar and there is only one component required for any of the grate bars.

The design of the grate is very flexible allowing not only wood but also other solid fuels to be burnt in the stove. The characteristics of the stove can easily be changed, if desired, simply by replacing one set of grate bars by another comprising bars of a different shape.

Figs. 4A to 4C show a grate bar 5' that is a modified version of the grate bar 5 shown in Figs. 3A to 3C. In -14 -Figs. 4A to 4C parts that correspond to ones shown in Figs. 3A to 3C are referenced by the reference numerals shown in Figs. 3A to 3C with a ' added as a suffix. It can be seen that the main difference is that the inclined portions 9' and the depressed middle portion 8' of the grate bar 5' are differently shaped, being curved and with the inclined portions 9' merging smoothly with the curved middle portion 8'. The curved shape of the bar 5' further assists in guiding fuel into the heart of the fire.

Claims

-15 -Claims: 1. A fuel burning stove comprising a grate for supporting fuel to be burned, the grate comprising a set of 5 separate grate bars extending approximately parallel to one another from a first side of the grate to a second side opposite the first side with spaces between adjacent bars, wherein the grate bars are supported at their ends with the tops of their ends at approximately the same level, that 10 level defining a first horizontal plane, and the tops of middle portions of the grate bars are lower than the first horizontal plane thereby defining a depressed middle portion of the grate.
2. A stove according to claim 1, further including a 15 riddling mechanism for moving one grate bar relative to an adjacent grate bar.
3. A stove according to claim 2, wherein a major component of the movement is in a direction approximately parallel to the longitudinal axes of the grate bars.
4. A stove according to any preceding claim, in which the top of the depressed middle portion of the grate is more than 30 mm below the first horizontal plane.
5. A stove according to any preceding claim, in which each grate bar generally comprises first and second raised ends, a depressed middle portion and inclined portions extending between the first and second ends and the depressed middle portion.

-16 -
6. A stove according to any preceding claim, in which the grate bars are wider at their ends and adjacent ends of adjacent bars are immediately adjacent to one another.
7. A stove according to claim 6, in which each grate 5 bar generally comprises first and second raised ends, a depressed middle portion and inclined portions extending between the first and second ends and the depressed middle portion, and a part of the depressed middle portion is of reduced width, whereby gaps are formed towards the middle 10 of the grate between adjacent bars.
8. A stove according to any preceding claim, in which the grate bars have top faces provided with recesses for retaining pockets of ash when, in use, fuel is burnt on the stove.
9. A stove according to claim 8, in which the recesses comprise longitudinal grooves in the top faces of the grate bars.
10. A stove according to claim 8 or 9, in which the recesses comprise dimples in the top faces of the grate 20 bars.
11. A stove according to claim 10, in which the dimples on a grate bar comprise a row of dimples extending along the bar.