CA1150575A - Coal burning heating apparatus - Google Patents

Abstract

COAL BURNING HEATING APPARATUS

ABSTRACT OF THE DISCLOSURE
A coal burning heating apparatus has a grate assembly supported above an incoming primary air supply and beneath an adjustable and removable hopper assembly. The hopper assembly adjusts vertically for different coal sizes and enables top loading of the apparatus to be realized. A
grate shaker assembly simultaneously pivots each of the horizontal grate elements, and a horizontal slot is provided in the grate assembly for insertion of a slicer member just above the horizontal grate structure to help remove ash.
The grate and hopper assemblies are housed in a frame member having a long internal heat exchange path. The primary air, directed beneath the grate assembly, is constrained to follow a path through the grate assembly and the coal set thereon. The heating apparatus can also be employed for wood burning upon removal of the grate and hopper assemblies and their related components.

Description

5~5 . .. . .. , . , . ,. .. ...... ..... .. j BacXground of the Invention i This invention relates generally to coal burning and in particular to a coal burning parlor stove having high efficiency.

Coal burning stoves have been available for many years. They have been used for centuries in Europe where coal is relatively plentiful. The commercially available European coal burning stoves are therefore highly developed, sophisticated, and in many instances very efficient.

In the United States, coal, like wood, is relatively plentiful and is a comparatively inexpensive alternative to oil, gas, or electricity. For many people, coal offers certain advantages over wood in terms of availability, cost, and storage requirements.

Unfortunately however, coal, unlike wood can vary significantly in those characteristics which maXe it more or less suitable for burning in a home coal stove. Coal is formed from organic matter under great pressure over the years. The variations among coals are related to the differing climatic conditions, different degrees of t~, .

bacterial action, and the pressure and ~emperaturs while the coal is being formed. Thug, for example, coal can have high inherent moisture content, up to forty percent in lignite;
differing degrees of volatiles, high volatile content producing a very smoky burn in most space heaters; and for example different degrees of ash content and fixed carbon.
In addition, coal comes in different particulate sizes.

In the United States particularly, the coal burning problem is very difficult if one is attempting to maximize combustion efficiency. The Europeans have developed efficient stoves and these stoves operate with a minimum of difficulty. The secret is that the European stove owners are burning European coal and European coal is evenly si~ed, has a relatively low ash content, and the ash falls easily away from the burning coal in a light flaky powder. European coal stoves are therefore specifically designed for that type of coal and that type of ash.
Unfortunately, the differences between American and European coal make European stoves generally unsuitable for effective and efficient operation when American coal is used. Ash shakeout and maintenance of proper fuel bed thickness prove to be extremely difficult. Also, the inconsistently sized and shaped AMerican anthracite for example, with its higher, more solid, lumpy ash content, continually foul the grates of the European stoves and impede oxygen flow.

Therefore a principal object of the invention is a coal burning heating apparatus for efficiently burning American coal. Other ob~ects of the invention are a coal burning stove having minimal maintenance, long life, ease of use, and long even burning rates. Yet a further object of the invention is a heating apparatus which can be converted for either efficient coal or wood burning operation.
The present invention is for use in a heating member adapted for hurning wood and includes a heat conducting frame member which encloses a primary combustion chamber and a secondary combustion chamber in gaseous communication with the primary combustion chamber, and a baffling arrangement in gaseous communication with the secondary combustion chamber for providing a long internal heat exchange path.
A vertically oriented, downwardly directed baffle is provided for separating the primary and secondary combustion chambers ! with a portion of the baffle being spaced from a bottom surface of the frame for providing an opening connecting the primary and secondary combustion chambers for providing the gaseous communication therewith. A primary air supply path provides air for promoting combustion in the primary combustion chamber, and a secondary air supply path extends at least along the downwardly directed baffle for providing preheated air to the secondary combustion chamber at the opening. A combus*ion products exit aperture is provided at a top portion of the frame and in gaseous communication with the baffling arrangement for providing an exit port for combustion products. Apparatus is provided for converting ~ the heat member to a heating member adapted for coal burning, 3, the apparatus including means for preventing preheated air sb/) h ' ~ r~
at the opening from entering the primary combustion chamber, this means including means for directing exhaust gases from the primary combustion chamber through a first portion of the opening to the secondary combustion chamber for passing through the long heat exchange path, and means for blocking a remaining portion of the opening for preventing air from passing between the primary and secondary combustion chamber.
A grate assembly is provided for holding coal with means for supporting the grate assembly above the primary air supply for the primary combustion chamber. Means is provided for effecting oscillating movement of the grate assembly and means is provided for directing unburned coal from a top portion of the heat member toward the grate assembly.
Thus, the invention is in the form of a conversion kit provided for converting a wood burning stove to a coal ! burning stove. The wood burning stove, for example the Vermont Castings Vigilant parlor stove, is initially set up in the field for providing efficient wood burning operation.
In a specific embodiment of the invention, the grate elements each have an elongated tooth member portion and a central supporting spine, the spine having, at a central portion thereof and in a supporting dimension normal to the plane of the tooth member, a dimensional extent which is greater than the extent of the spine in the normal direction at the end of the toothed member.
In another particular embodiment, the elongated portion of the tooth member has, at its ends, an annular collar or flange for cooperating with the side vertical grate sb/~v~

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for capturing -the grate element along its horizontal rotation axis. The grate element is thereby unable to move longitudinally in the horizontal direction.
The coal directing assembly in an embodiment of the invention may have a fixed hopper element cooperatively engaged with an upper frame member for directing coal from an aperture in the upper frame and a movable hopper element adjustably secured to the fixed hopper element at a bottom portion thereof for guiding coal from the fixed hopper element toward the grate elements. The fixed hopper element features a construction whereby first and second component members are adapted to cooperatively meet along a substantially vertical plane whereby the components secure the adjustable hopper in a fixed vertical position during operation of the heating member.
The shaker system for oscillating the grate elements may hàve a plurality of rocker arms, each arm being connected to a grate element at a keyed cross section of the grate at its end, the end passing through a corresponding keyed aperture in a rocker arm connection element. The rocker arms are connected and interlocked to the rocker arm connection element for synchronous pivotal movemen-t about their rotation axes and a connection arm shifting element is provided for moving the connection element back and forth along a sub-stantially linear path whereby the grate elements are oscillated in a rotary motion about their rotation axes by the rocker arms.
More specifically, the connection element has a sb/Ja ~ ' ' .
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S~575 body por-tion having integral therewith L-shaped lugs, one lug for each rocker arm. Each lug has a first cross-sectional area near the body member to wh.ich the lug is connected and a second keyed cross-sectiQnal area spaced apart from the body member. Each rocker arm has an aperture having a cross-sectional area corresponding to -the second keyed cross-sectional area and a thickness at the rocker arm aperture no greater than the minimum distance between the keyed cross-sectional area lug portion and the body member.
Thereby a rocker arm can lock onto the L-shaped lug and stably and securely rotate around the first cross-sectional portion thereof.
. In one embodiment of the invention, the stove is provided with a removable door-type element allowing access t~the-secondar.y..combustion~chamber- for---.removing ash built up therein. Furthermore, a slotted structure is provided for combustion gases escaping from the primary combustion chamber for directing those volatiles toward the secondary combustion chamber.

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~.~S'3575 Brief Description of the Drawin~ ' Other objects, features, and advantages of the invention will appear from the following description of a preferred embodiment of the invention taken together wlth the drawings in which:

Figure 1 is a front perspective view of the outside of a heating apparatus according to a preferred embodiment of the invention;

Figure 2 is a rear perspective view of the outside of a heating apparatus according to a preferred embodiment of the invention;

Figure 3 is a perspective cutaway front view of the inside of the heating apparatus of Figures 1 and 2 with the interior coal operating assembly removed;

Figure 4 is a cross-sectional view along lines 4-4 of Figure 3;

Figure 5 is a cross-sectional view along lines 5-5 of Figure 4;

Figure 6 is a cross-sectional view along lines 6-6 of Figure 4;

Figure 7 is a cutaway perspective front view of the heating apparatus of Figures 1 and 2 including the coal operating assembly according to the preferred embodiment of the invention;

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, Figure 8 is a cross-sectional view along lines ~-8 of Figure 7;

Figure 9 is a cross-sectional view along lines 9-9 of Figure 8;

Figure 10 is a cross-sectional view along lines 10-10 of Figure 9;

Figure 11 is a plan view of a typical horizbntal grate element; and Figure 12 is a cross-sectional view along lines 12-12 of Fig. 7.

Description of a Preferred Fmbodiment According to the preferred embodiment of the invention, the heating apparatus of Figs. 1-12 is constructed ror burning coal efficiently and can also be converted to a wood burning heating apparatus as described hereinbelow. Conversely, the heating apparatus can be originally configured as a wood burning device and can be converted to a coal burning stove by application of the principles and the structure of the preferred embodiment.
Thus for the purposes of the following description, it should be understood that while the coal burning configuration of the apparatus is the primary configuration being described, the illustrated heating member can be converted from a wood burning configuration to a coal burning configuration and vice versa.

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Referring to Fig. 1, a heating apparatus 8, according to the invention, has an exterior frame member 10 preferably made of a heavy-duty cast iron. The sides 12a, 12b, front 12c with doors 12e, 12f, back 129, top 12h with door 14, and bottom 12i of the frame member are joined to form an integral air tight unit. The front pivoting doors 12e, 12f, allow the ~leating apparatus to be opened from the front for both loading if desired and for viewing the com-bustion when the heating apparatus is used as a fireplace, A top cover 14 of the apparatus, has hinges 15a, 15b which allow it to pivot to an upward position, whereby coal can be loaded into a primary combustion chamber 16 (Figure 3) through a smokeless loading double door arrangement 17. Top cover 14 is interconnected to a smaller door 17a and the combination is designed to maintain the opening substanti-ally clear or combustion gases when the top cover or door 14 is pivoted to an open condition. Thus, even when the stove is in operation, coal can be loaded merely by dropping it into the primary combustion chamber gravity fed hopper 17b (Fig. 7). A fireproof seal around the top frame opening provides an air tight fit between cover 14 and the frame member.

Referring to Figures 2 and 3, air is fed to the primary combustion chamber 16 through a primary inlet port 18 and a primary air supply flow path 20 (Figure 3). Inlet port 18 is thermostatically controlled by a thermostat 21 which operates a damper 22 covering an aperture 23 (Figure 6) in the back frame member 12g. Thermostat 21 is for ,, .
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example an 5" coil of bimetallic material connected to damper 22 by a flexible chain 24. Heating apparatus 8 i9 also provided with a damper control lever 25, a rotatable flue member 26, and a manually controlled night air inlet port 27 in sids member 12a. (Night air inlet port 27 ii of use when the apparatus operates as a wood burning apparatus.
See copending parent application Serial No. 046,326, filed June 7, 1979 (a continuation of U.S. Serial No. 837,608, filed September 28, 1977), both of which are incorporated herein by reference.

Referring to Figure 3, in which elements essential ror efficient coal burning operation have been removed, and wherein efficient wood burning operation can be effected, primary air entering through aperture 23 (Fig. 6) travels through primary air supply path 20 to the primary combustion chamber 16. The primary combustion chamber is generally defined by the substantially vertically oriented downwardly extending fireback baffle 28, the side walls 12a and 12b of the frame member, the front doors 12e, 12f and front wall 12c of the frame member and the top 12h and bottom 12i frame member panels.

A right-hand portion 29, of baffle 28 further provides, a partial separation between the primary combustion chamber 16 and what, ic wood were being burned, would be used as a secondary combustion chamber 30. Durin~
wood burning operation, the secondary combustion chamber i3 connected to and is ln gaseous communication with the ., _~ .

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primary combustion chamber through an opening 31 in baffle 28. As described below, when coal is burned, this opening is partially blocked and serves in part to direct col~usted gases toward a long heat exchange path. A cornbined primary/secondary air supply flow path 32 (Fig. 4) is pro~
vided, for the primary and secondary combustion chambers, from thermostatically controlled inlet port 18, and comprises a first perforate section 36 (Figure 4) which extends from the inlet port 18 to substantially the beginning of the secondary combustion chamber and a second perforate or apertured conduit 38 which extends within the secondary combustion chamber along a bottom section of baffle portion 29 around opening 31.
There is further provided a third air supply path 40 which may be used to provide air from manually controlled inlet 27 (Fig. 2) to the secondary combustion chamber for maintaining minimum wood burning activity during night or other selected periods of low heat output operation. Air supply path 40 further provides additional oxygen for secondary combustion in the secondary combustion chamber of the products of wood burning primary combustion.
Behind the fireback baffle 28 are a plurality of connecting smoke passages 104, 106, 108 (Figure 4). These passages direct the,spent flue gases from the secondary combustion chamber along a long heat exchange path, first to the left end of the apparatus, (looking from the front), then into an upper channel or passage 106 and back toward ms/
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i75 the right portion of the stove, and then further up into the uppermost passage 108 and back toward the left portion of the stove, where they finally exit through the flue collar 26. The secondary combustion chamber, taken toge-ther with the smoke passages, make up the flame path. Since ~he heat of the flue gases is considerable, and is transferred to the surfaces of the stove as the flue gases traverse the passages, a significant amount of heat is given off to -the room rather than being lost up the chimney. In addition, since the passages are adjacent to the primary combustion chamber, higher temperatures are maintained within the primary combustion chamber, which aids in burning the volatile gaseous products from the burning fuel~
The flue collar 26 is preferably rotatable to ; allow operation of the apparatus with either a horizontal exit or a vertical exit position. The flue collar is attached to an inclined back portion 50 which is securely positioned on the back and top frame portions of the apparatus. The flue collar is secured to the inclined surface of the back portion by two flue collar bolts 56 `~ (oniy one is shown). The two bolts are secured on opposed sides of the flue collar.
Referring to Figures 4 and 6, the thermostatically controlled inlet port 18 supplies air for both the primary air flow 20 and primary/secondary air flow 32. Ambient air enters through aperture 23 in frame back wall 12g and is almost immediately divided between the flow paths, 20, 32 by ms/~

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a dividiny plate mer~er 70. That portion of the incoming air which passes into the flow path 32 is directed along the fireback baffle 28 and is constrained to follow a path adjacent to the fireback baffle by an enclosing mer~er 72.
Enclosing mernber 72 directs the air flow toward opening 31 in baffle 28. Along flow path 32, however, there are apertures 73 in baffle 28 which divert a portion of the flow to the primary combustion charnber. In order to provide a substantially uniform flow of air into opening 31, (during wood burning operation), the cross-sectional area of the supply path defined by enclosing member 72 in combination with baffle 28 increases substantially as the path approaches the opening, as shown in Figure 4. This provides the necessary volume distribution of the flow to promote substantially uniform air flow in the opening. At the opening 31, the enclosing member 72 ends in a substantially spaced apart parallel alignment with the baffle 28, for example at 80 (Figure 3) so that the flow of secondary air is substantially unimpended into the secondary chamber at opening 31. The secondary air supplied at opening 31 is also preheated due to its proximity with baffle 28 so that the efficiency of the secondary combustion chamber (during wood burning operation) is increased.
That portion of the ambient air passing through aperture 23 which follows primary flow path 20, passes through the baffle 28 near the lower base of the baffle (Figure 3) and is supplied to the primary combustion chamber along side wall 12a. A conduit system can be ernployed ms/ ~'~' ,, ~ f~

during wooc1 burning operation if desired. Primary air is thus provided to promo-te a continuous flow of combustion supporting oxyyen across the entire bottom depth of the combustion chamber.
Referring to Figures 4 and 5, the baffle arrangment for directing the flue gases along the circuitous heat exchange path in the space between baffle 28 and back wall 12g has a lower baffle 90 and an upper baffle 92. Illustrated lower baffle 90 has two cast plate members 94 and 96 which meet along their length to form baffle 90 when the fireback baffle 28 is put into position. Baffle 90 extends substantially from side wall 12b to a position near side wall 12a. Illustrated baffle 92 extends above baffle 90 and has a pair of tabular cast supporting members 98, 100 which support a baffle plate 102 extending substantially from side wall 12a to a position near side wall 12b. The flue gases thereby are directed from the horizontally directed passage 104 to horizontally directed passage 106 and then to third horizontally directed passage 108 from which they exit through flue collar 26.
The heating apparatus also has a damper which enables the apparatus both to be used as a parlor stove and as a fireplace. In the position shown in Figure 5, the apparatus can be used as a fireplace with the flue gases exiting from the primary combustion chamber along a path generally indicated by arrow 114. When the damper is closed, that is,,placed in a position indicated by dotted ms/r~

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line 116, the heating apparatus operates as a stove and the flue gases exit, Eor wood burning operation, subst~ntially as shown by the arrow 120 (Figure 3). (When fuel is loaded into the apparatus through top cover member 14, the flue must be in the opened position or otherwi-se smoke will pour out of the aperture in the top panel 12h).
Referring to Figures 2 and 5, back wall member 12g has a series o~ corrugations 122, 124, 126, which protrude outwardly from the plane of back wall member 12g. These corrugations provide additional heat radiation surfaces for the heating apparatus for increasing the heat delivery to the surrounding air. In addition, the corrugations provide convenient means for channeling "night air" from the manually controlled inlet port 27 to the secondary combustion chamber through night air flow path 40. T~us, the lowermost corrugation 126 is blocked off by a plate 130 and is used to channel the night air into or at least toward the secondary combustion chamber.
Referring to Figure 7, wherein the additional components for burning coal have been added, the stove 8, when it is configured for burning coal includes a grate assembly 140, hopper assembly 17b and a plurality of baffles including upright baffles 142, 144. An ash pan 146 is alSQ
provided. The addition of these components effectively convert the stove from a wood burning to a coal burning configuration.
The grate assembly 140 has a plurality of rotatable, grate elements 152,-154, 156, arranged in a mSk-i~

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s horizontal plane and w~ich are surrounded a-t their periphery by a vertical grate assembly having a rear vertical grate 160j a front vertical grate 162, and side vertical grates 164 and 166 (see Figs. 7 and 8). The elements of the grate assembly define the coal suppor-ting basket wherein coal combustion takes place.
Coal is directed to the grate assembly through the hopper assembly 17b. Illustrated hopper assembly 17b has an upper fixed hopper 172 and a lower adjustable hopper component 174. By adjusting the height of lower hopper component 174 above the upper planer surface of grate elements 152, 154, 156, the height depending primarily upon the coal particulate size to provide a suitable thickness coal burning bed, a properly configured coal burning region can be obtained.
The primary air enters the primary combustion chamber at a level below the grate assembly. It will be recalled that primary air enters through one of two paths.
The first path 20 provides the primary air to the left side portion of the apparatus while the second path 32 provides primary air through apertures 73 in baffle 28. It is important that this air not bypass the grate assembly and the bed of burning coal supported therein; and therefore, a baffle structure is employed to prevent the primary air from bypassing the coal bed. At the left side of the grate assembly, baffle member 144 here, in combination with side grate 164, prevent the primary~air from bypassing the grate mS/rf~'~:

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assembly on the left hand por-tlon of the apparatus, the front of baffle 144 mating with -the front panel 12c o the heating apparatus. A similar structure having baffle 142 and vertical grate 166 prevent primary air from bypassing the coal bed on the right side of the primary combustion chamber. At the front of the grate assembly, vertical baffie 162 has a gasket material 180 secured thereto which provides sealing engagement with the front doors 12e and 12f when they are closed. This construction prevents primary air from bypassing the grate assembly at the front of the stove.
At the rear of the primary combustion chamber the ` rear vertical baffle blocks the path of prim~ry air attempting to bypass the coal bed there. Further, at this rear section, a left hand portion of the opening 31, up to at least vertical baffle 142, is blocked by a plate-like element 182 to prevent primary air and/or combustion products from escaping therethrough, to prevent secondary air from being provided thereat, and for cooperating with the baffle 28, vertical rear grate 160, and side ~rate 142 to prevent primary air from bypassing the grate assembly.
In addition, the blockage element 182 is preferably a removable door element which can be removed as desired to permit removal of the ash material accumulating behind it.
An ash pan 146 is provided beneath the grate assembly. The products of combustion exit the primary combustion chamber through slots 188.

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Referring to Figures 7 and 8, the yrate assembly is assembled into the stove in the ~-tove as follows.
Starting from the "empty primary combustion chamber" of Figure 3, the right side baf~le member 142 is first placed in position. Next, the rear vertical grate 160 is inserted into its operative position adjacent side baffle member 142 and is in part supported thereby. Baffle 142 thus prevents longitudinal movement of rear grate 160 and helps prevent forward transverse movement of grate 160 by a mating protruding rib member 189. The rib member 189 engages the rear grate in a substantially sealing relationship for preventing either combustion gases from exiting other than through slots 189a or primary air from bypassing the primary combustion chamber.
Next, the left baffle 144 is inserted into the primary combustion chamber and is supported by the rear vertical grate on one side and by a protruding tab member extending from the front frame 12c. Next, a shaker mechanism 192 is assembled outside the stove and is placed into the stove near to its operative position. The shaker assembly, as described in more detail below, has a plurality of rocker arms 194 connecting a connection element 196 to the horizontal grate elements 152, 154, 156. The connection element 196 is moved in a substantially linear direction by a rod member 198 which in turn connects to a shaker handle 200 at the front of the stove.
Next, the horizontal grate elements 152, 154, 156 are inserted, first into the grate supporting apertures ms/ ;`~

provided in the right baffle 1~2 and thereafter into the grate supporting apertures provided in the left baffle 144.
Before being inserted into the left baffle apertures, however, ends 202 of the horizontal grate elements are inserted through supporting apertures 203 of the rocker arms 194, and then through the apertures in the baffle 144. The grate elements are moved to the left to their extreme stop position (corresponding to the termination of the keyed structure on ends 202); and thereafter the right vertical grate 166 and the left vertical grate 164 are placed in position. Grate 166 is positioned to the right of a flange or collar 206, and resting, in the illustrated embodiment, on the right end 208 of the horizontal grate elements. Each grate element has the flange 206 positioned to the left of right vertical grate 166 to prevent lateral right hand movement of the horizontal grate elements. Thus, the horizontal grate elements are "captured" and are thereby longitudinally fixed in an operative position.
The final element of the grate assembly, the front vertical grate 162 is inserted into capturing channels on the right and left vertical grates respectively. Thereby the front vertical grate is captured and held against horizontal movement; that is, the interlocking configuration of the side vertical grates and the front vertical grate prevents the side grates from moving in a lateral horizontal direction. There is thus formed a grate assembly defining a coal supporting "basket". The bottoms 207 of the vertical grate elements are preferably "toothed" to further direct primary air into the coal bed.

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Each of the illustrated horizontal grate elements 152, 154, 156 has the identical structural configuration (see Figure 11). Each horizontal grate element has at one end, for example an end 208, the flange or collar 206, and at its other end 202, a keyed cross-sectional area portion 210 which mates with a corresponding keyed area in the rocker arms 194 of the shaker assembly. The keyed cross-sectional portion 210 has a limited longitudinal extent.

The central portion of the horizontal grate elements are "toothed". That is, a series of protruding tooth-like members 212 extend outward on both sides of a central supporting spine 214 (Figures 8 and 11)~ These grate elements, when in their operative positions, form a substantially closed surface for suporting the coal particulate and yet a substantially opened surface for allowing ash to settle therethrough.

The supporting spine 214 is particularly advantageously structured to reduce warpage of the grate element. Therefore, the spine has a greater vertical extent at its center than it does at either end. This greater vertical extent provides greater support and effectively reduces warpage of the horizontal grate elements under the high temperatures to which they can be exposed during the coal burning process.

Referring to Figures 8, 9, and 10, the shaker assembly 192, as noted above, has a connection element 196 , .

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which connects the plurality of rocXer arms 194 so that, ~ ' when the connection element is moved along a substantially linearly directed path by rod member 198, the rocker arms all move simultaneously therewith and pivot about respective horizontal axes 220 of the respective horizontal grate assemblies. Each rocker arm has two apertures, the first upper aperture 203 through which the keyed end 202 of the horizontal grate element extends, and the second aperture, a keyed aperture 224 designed to swing around and beneath a key portion of an L-shaped lug 226 which is integral with the connection element 194. Each rocker arm is secured for rotating movement around the L-shaped lugs 226 by passing the rocker arm at the keyed aperture 224, set at a ~ubstantial angle preferably greater than 45 to the vertical (Fig. 9), over the lug 226, and then rotating the rocker arm to its vertical position. Thereby, each rocker arm can rotate about the lug 226 for a limited angular extent while rernaining stably and securely fastened thereto.
The shaker arm rod 198, which had been previously positioned at its free end in an aperture at the e~d of the connection element 196, extends, at its other end, through the front of the heating apparatus and connects to the shaker handle 200, for movement therebyO

As noted above, the hopper assembly comprises the upper fixed hopper element 172 and a lower moveable hopper element 174. The upper hopper member has integral therewith lugs 201 which rest on the upper frame member 12h at the loading aperture therein. Thus the entire hopper assembly .

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i75 can be easily removed, for example, if it is desir0d to bur~
wood.

Hopper element 172 is composed of two components which mate along substantially vertical seams 240 and are connected at the seams, for example, by a screw connection.
The upper hopper 172 has a door 17a at the top thereof which is interlinked to the upper aperture door 14 so that when the upper door is opened the lower door will thereaftér open automatically with it. In this way, condensation at the top of the hopper is reduced and the quantity of gases passing into the area being heated is reduced. In a preferred embodiment of the invention, the hopper elements are interconnected so that upper hopper member 172 holds lower hopper number 174 in a press fit. The press fit is aided by ribs 242 on the upper hopper components and 1ip 244 on the lower hopper respectively. The ribs and lip structure provides an increased degree of stability to the hopper systeln.

The blockage member 182 closes the portion of opening 31 which extends into what will become a slightly reduced size primary combustion chamber. This blockage member is preferably, for example, screw mounted so that it can be rernoved periodically to remove ash from behind baffle 28. The ash accumulates there during normal operation of the stove.

In operation, the damper is moved to the open position to obtain higher stack temperatures, for example ~ 3 ~

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s~s when the apparatus is operating in the spring or fAll, or when the coal is first being lit. Thus the damper advantageously enables the stove to adapt to different coal operating modes of the apparatus.

There i8 thus achieved a coal burning heating apparatus which provides a large quantity of primary air beneath a grate assembly, which provides baffles to direct the primary air through the yrate assemblv and hence through the burning coal bed, the air being heated as it passes therethrough to help improve the combustion efficiency in the primary combustion chamber. The air, when the damper is closed, as it exits the primary combustion chamber is forced to and is directed by baffle 142 (which has the only exhaust opening for combustion products) to exit through a right hand portion 250 of the opening 31. The combustion products thereby pass through the long interval heat exchange path described above and thereby, a higher efficiency coal burning apparatus is achievedO

The illustrated ash removal apparatus is especially effective for American coal. The ash removal system uses a dual operation whereby movement of shaXer handle 200 causes axial rotation of the horizontal grate elements 152, 154, 15fi, and simultaneously, the front vertical baffle 162 is supported by the side vertical grates above the plane of the horizontal grate elements so that a slicer member can be inserted into a slot 252 between the bottom of the front vertical grate and the top plane of the '~, ' .

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horizontal grate elements for further advantageously assisting in ash removalO 1`he slicer member is a substantially flattened poker which fits in the slot 2520 Additions, subtractions, deletions, and other modifications of the preferred embodiment of the invention will be obvious to those practiced in the art and are within the scope of the following claims.

What is claimed is:

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Claims (12)

1. For use in a heating member adapted for burning wood comprising a heat conducting frame member enclosing a primary combustion chamber, a secondary combustion chamber in gaseous communication with said primary combustion chamber, and a baffling arrangement in gaseous communication with said secondary combustion chamber, for providing a long internal heat exchange path, a vertically oriented, downwardly directed baffle for separating said primary and secondary combustion chambers, a portion of said baffle being spaced from a bottom surface of said frame for providing an opening connecting said primary and secondary combustion chambers for providing said gaseous communication therebetween, a primary air supply path for providing air for promoting combustion in said primary combustion chamber, a secondary air supply path extending at least along said downwardly directed baffle for providing preheated air to said secondary combustion chamber at said opening, and a combustion products exit aperture at a top portion of said frame and in gaseous communication with said baffling arrangement for providing an exit port for combustion products, apparatus for converting said heating member to a heating member adapted for coal burning comprising
1. Claim 1 cont'd.
   means for preventing preheated air at said opening from entering said primary combustion chamber, said means including means for directing exhaust gases from said primary combustion chamber through a first portion of said opening to said secondary combustion chamber for passing through said long heat exchange path, and means for blocking a remaining portion of said opening for preventing air from passing between said primary and secondary combustion chamber, a grate assembly for holding coal, means for supporting said grate assembly above the primary air supply for said primary combustion chamber, means for effecting oscillating movement of said grate assembly, and means for directing unburned coal from a top portion of said heating member toward said grate assembly.
2. 2. The apparatus of claim 1 further wherein said grate assembly comprises at least two grate elements, each rotatable about a respective horizontal axis, a front vertical grate, a rear vertical grate, and first and second side vertical grates, and means for supporting said front vertical grate above the level of said rotatable grate elements for providing a horizontally directed slot through which a slicer element can be inserted for stoking said coals in said primary combustion chamber.
3. 3. The apparatus of claim 2 further wherein said grate elements each comprise an elongated toothed member having a toothed portion and a central supporting spine, said spine at a middle portion thereof having, in a supporting dimension normal to the plane of said toothed portion, an extent which is greater than the extent in said direction at the ends of said toothed member.
4. 4. The apparatus of claim 1 further comprising side baffle means, means for supporting said side baffle in a spaced apart relationship from said frame bottom for providing an opening through which a portion of the primary air supply can pass to the space between the grate elements and the frame bottom, and said supporting means includes supporting apertures in said side baffle means and said exhaust directing means for supporting said grate elements for said rotary movement.
5. 5. The apparatus of claim 4 further wherein each of said grate elements comprises an elongated toothed member having first and second extending elongated supporting members extending from respective ends thereof, said supporting members cooperating with said supporting apertures to position said grates along horizontally directed rotation axes, said first elongated member having a flange portion for cooperating with a said side vertical grate for capturing said grate element along said horizontal rotation axis.
6. 6. The apparatus of claim 4 further wherein said coal directing means comprises a fixed hopper element cooperatively engaging an upper frame member for directing coal from an aperture in said upper frame member, and a movable hopper element, adjustably secured to said fixed hopper element at a bottom portion thereof for guiding coal from said fixed hopper element toward said grate elements, said fixed hopper element having first and second component members adapted to cooperatively meet along substantially vertical seams and to secure said adjustable hopper in a fixed position therebetween by a press fit.
7. 7. The apparatus of claim 2 wherein said front vertical grate has a gasketing member on a side thereof facing the front of the heating member for providing a sealing structure when a front door assembly of the heating member is closed, whereby primary air from beneath the grate assembly cannot by-pass the coal burning region by passing between the front door assembly and the front vertical grate.
8. 8. The apparatus of claim 1 further wherein said grate assembly comprises a plurality of grate elements rotatable about a horizontal axis, each grate element having first and second elongated supporting portions at first and second ends, respectively, thereof, said supporting portions defining an axis about which said grate elements rotate, and each said grate element having a first supporting portion with a keyed cross section, said supporting means supports said grate elements for rotary movement about respective axes, and said grate oscillating means comprising a plurality of rocker arms, each arm connected to a said grate element at the keyed cross section of the first supporting portion, said first supporting portion passing through and engaging a corresponding keyed aperture in said rocker arm, a rocker arm connection element for interlocking said rocker arms for synchronous pivoting movement about said rotation axes, and a connection element shifting arm for moving said connection element back and forth in a substantially linear direction whereby said grate elements are oscillated in a rotary motion about their rotation axes by said rocker arms.
9. 9. The apparatus of claim 8 wherein said connection element comprises a body member having an L-shaped lug integral therewith for each rocker arm attached thereto, said lugs having a spaced apart relationship to each other, each said lug having a first cross-sectional area near said body member to which said lug is connected and a second keyed cross-sectional area spaced apart from said body member, and each said rocker arm has an aperture having a cross-sectional area corresponding to said keyed second cross-sectional area and a thickness at said rocker arm aperture no greater than the minimum distance between the lug portion having the keyed second cross-sectional area an said body member, whereby a said rocker arm can lock onto a said L-shaped lug and stably and securely rotate a limited angular extent around the first cross-sectional portion thereof.
10. 10. The apparatus of claim 1 further comprising means for removably securing said blocking means in position whereby said blocking means can be removed for providing access to said secondary combustion chamber for removing ash accumulated there.
11. 11. The apparatus of claim 1 further wherein said means for directing has slit apertures at an upper portion thereof for providing gaseous communication from said primary combustion chamber to said secondary combustion chamber.
12. 12. The apparatus of claim 1 further comprising a damper member moveable between A first position wherein exiting combustion products of said apparatus have a high stack temperature and a second position wherein said combustion products exiting said apparatus have a lower stack temperature.