AU595005B2 - Combustion means for solid fuels and holding board and ignition means for the same - Google Patents

Description

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AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Application Number: Lodged: 6 T/5,/V7 Class Int. Class 9 95 Complete Specification Lodged: Accepted: Published: Priority Related Art: 3885 7 APPLICANT' S REFERENCE: JP c

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Name(s) of Applicant(s): Daihachiro Murase Address(es) of Applicant(s): 11-12 Mitsukeyama 1-chome, Ibasaki-shi, Osaka-fu,

JAPAN.

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C *ee C i# 0 0 @0 ne Adiress for Service is: a 0o PHILLIPS ORMONDE and FITZPATRICK Patent and Trade Mark Attorneys a. o 367 Collins Street a Melbourne 3000 AUSTRALIA 04 0 0 o0 Complete Specification for the invention entitled: COMBUSTION MEANS FOR SOLID FUELS AND HOLDING B 1 ORD AND IGNITION MEANS FOR THE SAME Our Ref 46660 PCF Code: 46834/46842 The following statement is a full description Of this invention, including the best method of performing it known to applicant(s): 6003q/1 1 The present invention relates to a combustion device for solid fuel which may be used as a heating system for a house or a green house or for a boiler, a bath, etc., and which is suitable for using solid fuels such as coal, coke, charcoal, oval briquettes, etc.

Petroleum fan heaters and petroleum stoves are currently widely used as heating or combustion devices.

There are however many problems in operating these heating devices. These problems are the result of the amounts of petroleum that need to be supplied, the instability in price of petroleum, the inherent fire dangers and care that must be taken to safely store and handle petroleum, and so on.

Therefore, attention has been given to the use of solid fuels such as oval briquette, briquette coal, etc.

which are low in cost and more safe to handle. Combustion

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C apparatuses using these fuels are presently employed for use in factories, green houses, as heating systems in cold districts, etc. An example convention combustion device is shown in Japanese Utility Model Publication No.

S23003/1956, which has a construction that includes a roaster having air slits provided at the lower position of a combustion chamber. Solid fuels are piled thick on top of the roaster and burnt while ashes drop out of the roaster so as to ensure consistent ventilation.

Solid fuels having a low ash content of 10% or less are relatively cheap and of high calorie. When solid fuel of this type is used, as well as removing the feat of air contamination, ve:cy little of the ashes remain in the 30 combustion device during burning. Combustion devices have been proposed which use fuels such as charcoal, lignite, S coal pitch coke, petroleum coke, carsina coke, etc.

(Japanese Patent Publication (unexamined) Nos. 89905/1984, and 100302/1984). These combustion devices comprise a plane holding board having no slits which hold solid fuel having low ash content. A combustion chamber is provided to cover the holding board, the lower end of the chamber being spaced from the holding board or having holes for 39 2- VHF U NT -t introducing air. The spaces for introducing air function to accelerate burning of solid fuels which have been ignited, and the solid fuels having such characteristics as above mentioned can efficiently burn while producing less ashes on the holding board. In the combustion devices as shown in the above literature, igniting materials such as paper, firewood, and molded rods made of compressed paper or fibercs, which are dipped in oil and fats are used for ignitilng solid fuels piled on the holding board. Igniting means are provided to produce a spark with use of ceramic heater, carbon rod or metal rod. A gas burner is also provided at the lower surface of the biolding board to jet flames upwards.

In Figs. 13 to there are shown some conventional combustion devices. In Fig. 13 showing one embodiment using oil-dipped igniting material 31, 38 as fuels, 2a is a space for introducing air for combustion and 2a' is a hole for introducing air. For igniting solid fuels, the igniting material is lighted and burnt to produce heat and flames. In Fig. 13 showing one example using a ceramic heater, 32a is a ceramic heater, 32b is an electrode, and 37 .s a lead wire. Fig. 13 (c) is a cross sectional view of Fig. 13 and Fig. 13 (d) shows another example using a ceramic heater 33a. Fig. 13 is one embodiment using a gas burner 34.

*o°o The solid fuels such as coal, oval briquettes, etc.

o°O0o are required to have such properties as a long combustion life, a steady heat and a long lasting fire. Since these o°°o solid fuels have ash content of 10% or more, such solid o 30 fuels remain as ashes keeping its original shape on the holding board even after completion of burning io as to .o maintain a steady heat for a long time. Accordingly, a large amount of ashes remains after completion of burning which requires troublesome labour such as the removal of ashes from the air holes of roasters and disposal of the ashes. Furthermore, in the combustion devices as shown in the above literature, if a small amount of ashes or remnants of fuels is produced, and it is required to be 39 -3- VHF i V Zf f 1 removed from the holding board. Thus, there is a need for an improvement for achieving efficient burning without such disadvantages.

Furthermore, as to the igniting means, the ceramic heater has the disadvantage in that fine ceramics of high price is used and, in addition, electrode and lead wire are easily deteriorated due to high temperatures. The igniting materials as mentioned above, such as paper or firewood, or oil-dipped molded materials, are required to be lighted with a match, etc. which is troublesome. The use of gases is accompanied with danger. These are problems to be improved.

According to the present invention, there is provided a combustion device for solid fuel, including: a base stand with an opening therein, an imperforate heat resistant holding board locatable to S*c close said opening; a combustion chamber standing on the base stand with the e C holding board at the bottom thereof; c 20 a wiper arm pivoted for horizontal wiping movement over I the base of the combustion chamber; an inlet means at a lower edge of said chamber above the 1 stand base(~, and/or in a surrounding wall of said chamber, whereby combustion air may enter as exhaust gases leave the combustion chamber; an exhaust pipe for the exhaust gases; o generally tubular gas-flow heat-exchange ducting putting a 0 the combustion chamber and exhaust pipe into .00o communication; and gee 30 means capable of moving the holding board into or out of 0 the opening for removal of ash or other residue.

°0 0 In the combustion device of the present invention having the above construction, even solid fuels having high ash content such as charcoal, oval briquettes, etc.

can be burnt efficiently and the remaining ashes can easily be removed by opening the holding board.

Furthermore, solid fuels having low ash content such as cokes, etc., which tend to crack up during burning to 39 -4- VHF .j become fine particles which can fall down through the slits of a roaster, can efficiently be burnt by accumulating them on a fire grate in a shape of plane board having no air slits and by igniting them.

Accordingly, various cokes which are conventionally molded into a fixed size so as not to fall down from air slits of roaster, can be used without any molding process in its original shape, even if their size is small, without fear of falling down from the holding board and of incomplete burning. In addition, since the solid fuels can be almost completely burnt in an atmosphere of high temperature, there is little fear of finely powdered cokes in a stream of high temperature,; if any, being exhausted out of an exhausting pipe by being introduced into a connecting branched pipe of the heat-scattering portion and further into the base portion. Air contamination CCc caused by noxious gases, soot and dust, and ashes can be tt prevented or minimised. Thus, the combustion device of the present invention can be used as a combustion means for boilers for heating water and providing steam, and for heating systems for green houses or rooms which sends warm t air thereto by providing a fan, with the use of inexpeisive solid fuels.

The ignition means which is also used as a fire grate, preferably comprises a heat-generating substance o using commercially available nichrome wire without using o-oO fine ceramics which is expensive and is difficult to produce, and a base board for holding the heat-generating a* a substance comprising usual material and shapes. The o.s 30 heat-generating substance is wrapped with a heat insulating material and fixed in a groove in the base 00 plate, whereby the heat-generating substance is not exposed to and contact with oxygen in the air, and can be prevented from oxidation by burning, and deterioration by burning at high temperatures. Since the ventilation into the grooves in which the heat-generating substance is embedded can be made smooth by provision of a number of air holes and by continuous liberation of the grooves, an *t

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I; I I I Ia 0 r0 *1014 o p air-cooling function can be achieved so as to improve protection of the heat-generating substance. Furthermore, since the surface-protecting portion is made of such material that melting and remaining ashes of the solid fuels will preferably not adhere, the remnant of the sc.id fuels can be easily removed.

The following description refers in moe detail to the various features of the combustion device of the present invention. To facilitae an understanding of the invention, reference is made in the description to the accompanying drawing where the combustion device is illustrated in preferred embodiments. It is to be understood that the combustion device of the present invention is not limited to the preferred embodiments as illustrated in the drawings.

Fig. 1 is a perspective view of the combustion device for solid fuels according to the present invention, which is exploded at the upper and lower portions; Fig. 2 is a vertical sectional view of the 20 combustion device of Fig. 1, in which the upper portion of the combustion device is mounted on the base stand of the lower portion thereof; Fig. 3 is a plane view of the lower surface of the base stand of the combustion device of Fig. 1; Fig. 4 is an enlarged front view showing an embodiment of a means for rotating the holding board downward which is an essential portion of the combustion device of the present invention.

Fig. 5 is a cross sectional view of Fig. 4, taken 30 along a line X-X; Fig, 6 is a perspective view showing another embodiment of the combustion device of the present invention; Fig. 7 is a partially cut plane view of the base stand showing another embodiment wherein the holding board which is an essential part of the combustion device of Fig. 6 is slided out of the base stand; Fig. 8 is a plane view showing a lower surface of I II aC'

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VHF k;tAtr r _~i 7 the holding board of Fig. 7; Fig. 9 is an enlarged pespective view showing one embodiment of an ignition means which is used in the combustion device of the present invention; Fig. 10 is a cross sectional view of the essential part of the ignition means of Fig. 9; Figs. 11 to ere perspective views showing other embodiments of the ignition means among them, (b) and being cross sectional views partially cut; Fig. 12 is a cross sectional view of the ignition means in operation; and Figs. 13 to are each embodiment of thr ignition means used in the conventional combustion devices for solid fuels, and showing cross sectional views and showing a plane view of Fig. 13 I The combustion device for solid fuel of the present Sinvention will be explained in details in relation with the accompanying drawings.

I 20 In Fig. 1, tho combustion apparatus A comprises a 'cc C combustion portion B, a heat-scattering portion 4 and an Sio, air-exhausting pipe 7, and is mounted on a base stand 1 in such a manner that the combustion apparatus can optionally be taken out. The combustion portion B is connected with a number of branched, scattering portions 4b which are in a shape of a flat box and provided on the heat-scattering portion 4. Each branched scattering portion 4b is o 0o connected with a scattering base portion 4a in a shape of '00 closed box. The scattering base portion 4a is connected o~o 30 with the air-exhausting pipe 7 and is provided with an V opening for taking out unburnt substances, remaining 0"0: ashes, etc in an appropriate position.

The combustion portion B comprises a solid fuel-holding portion 2, a combustion chamber 3 and a holding board 5 on the base stand 1. On four corners of the base stand 1 are provided supporting legs lb, and between the upper surface of the base stand 1 and the solid fuel-holding portion 2 is provided a space 2a having 39

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I a fixed dimension which is t'sed for primarily taking in air by means of legs 2b. The dimension of the space 2a is preferably experimntarily selected in such a manner the J amount of air to be taken in is in proportion with the amount of air to be exhausted from the exhausting pipe 7.

The dimension of the space 2a has a great influence on combustion of solid fuels. By applying appropriate balance between the amounts of air to be taken in and taken out, solid fuels can completely be burnt without accumulating in thickness, and without any means for forcibly sending air. When the dimension of the space 2a is too large, a large quantity of cold air is introduced into the combustion chamber so that the heat-scattering rate is over the heat-generating rate of solid fuels and Satmospheric temperatures in tho combustion chamber is lowered to cause the fire to go out. On the contrary, when the dimension of the space is too small, combustion t, ce becomes insufficient and also causes the fire to go out.

20 Accordingly, the dimension of the space ,s preferably 20 appropriately selected from results of experiment&.

SAlternatively, an opening 2a' for taking in air is provided on peripheral wall of the combustion chamber, and the amount of air is controlled by a controlling lid.

Otherwise, as shown in Fig. 12, on the peripheral wall of the combustion chamber there may be provided a number of o So opening 2a" for introducing air on the outer circumference oBoo of which controlling rings which are movable in an up or down direction are provided.

S The solid fuel-holding portion 2 and the combustion o 30 chamber 3 are connected with each other and are constructed integrally or separately. In the combustion chamber is provided the heat-scattering portion On the inner periphery of upper opening 3b of the combustion chamber 3 is fixed horizontally a lid 8 for opening the opening 3b. Numeral 8a is a balancing weight. The inlet for throwing fuels into chamber 3 is not limited to that as shown in the drawings, and the opening for baking in air on the peripheral wall of the combustion chamber may 39 -8- VHFi< V

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also be used as the inlet for fuels. On one side of the combustion chamber, each of the branched scattering portions 4b for scattering combustion heat are connected.

An edge frame Ic of the base stand 1 is used for preventing burning fuels from scattering from air-absorbing space 2a. The fuel-holding portion 2 includes a heat-keeping layer 2' having a fixed thickness 6 in its inside.

The heat keeping layer 2' is produced by plastering heat-insulating materials such as heat-resistance castable, heat-keeping brick, etc. on the inside of the fuel-holding portion, or the heat-keeping material is mold'd into fixed thickness and shape beforehand and is set on the inside of the fuel-holding portion. The solid fuels to be burnt are held by the inner space of the heat-keeping layer 2' and by the holding board 5 provided i "o on the base stand 1. The inner space of the heat-keeping r olayer 2' has a sectional shape of a reversed trapezoid or s a_ square, i.e. the inner peripheral wall of the inner space may have a shape which gradually widens downwardly or may .o extend vertically. When the amount of solid fuel is aS large, it can be accumulated up to the combustion chamber; The holding board 5 is formed by filling into a heat resistant metal frame 6 a heat-insulating material having the same property and effect as the heat-keeping layer 2' into a fixed thickness and shape. The surface of S*o the heat-insulating material may be reinforced by sintered oxidized or carbonized substances to improve heat resistance and durability of the holding board. Tha shape a 30 of the holding board is not limited to a plain square as S* shown in Fig. 1, and may be polygonal, circular, conical, 0 pyramidal, etc. When the shape of the holding board is 4r selected the fuel-holding portion 2 and the combustion chamber 3 are formed to have a horizontal sectional shape corresponding to that of the holding board, i.e. square, polygon, circle, etc.

T'he holding board 5, as shown in Fig. 2, is fixed to the base stand 1 on one side by a supporting means 9 in 39 -9-

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such a manner that the holding board can be rotated downwardly and, on the other isde, is supported horizontally in such a manner that the holding board can be set into or removed out of a setting hold la of the base stand 1 by an operating means 14.

The supporting means 9 comprises a supporting arm 9a which is pivotedly fixed to a setting fragment 9c hanging from the lower surface of the base stand 1 by means of a horizontal shaft. The lower surface of the holding board is adhered to the upper surface of the supporting arm 9a.

The operating means 14 comprises an inclined supporting rod 10 which is adhered to the lower surface of the metal frame 6 and is connected with a motor M 1 through a horizontal connecting rod 11, an arm 11', a pinion 12 and a worm 13. Numerals lla and lb are fixing pivots and 12a is a pinion shaft.

By driving the motor M i the pinion 12 engaging with the worm 13 is rotated at an angle of 180 together with the arm 11' in a circular trace as shown by a one-dotted chain line, whereby the holding board 5 is rotated downwardly in a hanging condition as shown by a S one-dotted chain line. Subsequently, the pinion is rotated at an angle of 1800 and brought back to original horizontal position to rotate the holding board from thG hanging condition to the horizontal condition so as to set the holding board into the setting hole la.

o The driving of the motor M is controlled by various limit switches and remote-control switches which S are provided on the base stand (not shown in the drawings) for the purpose of confirming the position of the holding board.

lb 1 In Figs. 1 and 2, a wiper 15 for sweeping the upper surface of the holding board 5 can reciprocally move, within a fixed angle.

In Fig. 3, a support shaft 15b which is set into a setting base portion 15' of the wiper 15 is projected out of the lower surface of the base stand 1. A projecting arm rod 15a is connected to an end portion of the support 39 39 VHF 5 5. ft4«.

shaft 5b at a fixed angle relative to the wiper 15. Thus, the wiper and the arm rod 15a respectively pivot about the support shaft 5b. The projecting arm rod 15a can contact an operating arm rod 17 fixed on a shaft of a pinion 16, and rotation of the rod 17 makes the rod 15 rotate within a fixed range. Numeral 19 is a spring for restoration.

Numeral 20 is a braking fragment which comprises elastomeric material rubber) and is provided at a fixed position on the base stand or the motor-setting frame. The braking fragment functions to regulate the rotation range of the operating arm rod 17 rotating together with the pinion 16 when the rod 17 stops. By driving the motor M the operating arm rod 17 on the pinion shaft rotating through the worm 18 rotates in the direction as shown by an arrow in the drawing while a pushing the projecting arm rod 15a against a spring 19 so that the wiper 15 sways at a fixed angle. At the end of It t this movement, since the operating arm rod 17 is disconnected from the projecting arm rod 15a, the wiper 20 is simultaneously restored to the starting place by the spring 9 for restoration.

Thereafter, when the motor M 2 is immediately stopped, under an inertia force, the operating arm rod 17 is constricted with the braking fragment 20. Then the o*,o operating arm rod is gradually stopped by the braking aaction without rotating over. In place of the braking fragment 20, any other braking mechanism may be provided o" on an of the motor M to further accelerate the a 0 braking effect.

In the preferred embodiment, swaying of the wiper *ooO and open1ing and closing of the holding board are sufficiently operated with the use of an electric battery cell using a 12(V) motor, and therefore, in the practical use, an electric battery cell can be used as an electric source.

In the combustion device in which the functions of the wiper and the opening and closing holding board can be effected as mentioned above, when burning is stopped or 39 -11-

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O3^^ i J r ct *C r 0 rr I 0 I 0 0$ I after burning is completed, by opening the holding board by downward rotation, ashes on the heat-insulating material 5' are dropped and put into an ash receiver 30 or a charcoal extinguisher. Then the holding board is rotated upward and restored to the original position, and the wiper 15 is operated to scratch out remnants adhered onto the surface of the holding board. The melted remnants on the holding board is cleaned by further opening the holding board, whereby subsequent burning can efficiently be effected.

The driving of the wiper can also be effected by using an electromagnet so as to sway a projected arm rod.

In another embodiment, the holding board, as shown in Fig. 4, is divided in the center, and each holding board 5, 5 rotates downward to drop down solid fuels, a small amount of remaining ashes after burning and unburnt fuels on the holding board. The construction in which each holding board is rotated downward is as follows: as shown in Fig, 4, a couple of hanging rods 21, 21 are fixed 20 pivotedly on the center of both sides of the base stand 1 by pivots 21a, 21a, and the holding boards 5, 5 are supported in such a manner that hollowed portions 21b, 21b provided on the side edges on the lower end of the hanging rods 21, 21 are suspended on supporting shafts 22, 22 provided to the inner ends of the holding boards. The outer ends of the holding boards are each connected with the base stand 1 by hinge pins 22a, 22a. Between operating fragments 21c, 21c provided projectingly on the insides of upper ends of the hanging rods 21, 21, there is provided a spring 23 which gives strength to the operating fragments 21C, 21C so as to assure the hanging of the hollowed portion 21 and the supporting shaft 22.

The operation of the hanging rods 21, 21 are as follows: the operating fragments 21c, 21c are pressed in the inner direction of arrows against the strength of the spring so as to move the hanging rods 21, 21 outward as shown by an arrow whereby suspension between the hollowed portion and the hanging rod is 39 -12- 6000 a 9 0 99 0 9 90 o 00 0 O9 9 0 0 s

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VHF i d' disconnected and the holding boards are separated from each other in the direction shown by an arrow to hang as shown by two dotted chain lines.

Furthermore, shape memory alloys may be used as materials for supporting and operating portions.

Fig. 6 is a perspective view showing another embodimniti of the combustion device of the present invention, which differs from the embodiment of Fig. 1 in the construction of the heat-scatteriig portion 4 and the holding board 5. In this embodiment, the heat-scattering portion comprises a base portion 2 on the base stand 1 and having a plane view of and a sectional view of square tube, and a curved, branched scattering portions 4b and 4b which is connected with the base portion 4a on its lower end and the combustion chamber 3 on its upper end. On the o base portion 4a is provided an air-exhausting pipe 7 in and appropriate position, S' 4 On the base rortion 4a are provided opening portions Son both front sides. From the opening portions remnants 20 are removed by pulling out a receiving frame which is placed inside, Alternatively, on the base portion is provided a door on the front end and cleaning is effected by opening the door. In the drawing, 3' is also a heat-scattering portion, 3" is an air-absorbing hole and o 4c is a catch ring, eo 4 he holding board may have various shapes such as a polygon, square, etc, and is not limited to a circle as o9 0 shown in Fig. 7. The outer circumference of the holding Sboard 5 is held with a holding frame 24. The holding S* 30 board is set into a setting hole la of the base stand 1 in 0 0o such a mranner that the holding board is supported on both side edges 27' 27' of the supporting board 27 provided on the back surface of the base stand 1 with the usa of a couple of guide rail; 25 compr.sing curved metal fittngs., One end of the supporting board 27 is Uo hD t he base stand by a hinge (not shown in the 0 'tW d the other end thereof is laid on the bacO base stand in such a manner that an inner a 39 -13i J rod 28 is set in an arc-shaped groove provided on the back surface of the supporting board 27. The operation of setting into or removing out of the inner end of the operating rod or removing of the inner end of the operating rod int. or out of the groove can be effected by rotating an outer end of the operating rod 28. In Fig. 7, 29 is a setting axis which is a center of rotation of the operating rod 28.

By rotation of the operating rod 28, the end of the supporting board 27 is disconnected from setting with the inner end of the operating rod to fall down, and the holding board 5 is separated from the setting hole and slides out to the end of the supporting board 27 by means of the guide rails 25, whereby the small amount of ashes produced during the combustion for a long period of time can be removed on a receiving plate In the above embodiment, the combustion device is not provided with an ignition means on the holding board and ignition is effected by using fire woods with a kindling wood, etc. or by directly igniting solid fuels.

Another feature of the combustion device is an ignition means which may also be used as a fire grate.

Fig. 9 is a perspective view of an ignition means 31a which is used also as a fire grate, wherein, on a ,oo surface of the base plate 32 of circular plate, there is So engraved a groove 33 in a spiral shape into which a 6 heat-generating substance 34 comprising nichrome wire, etc. is set. Numeral 35 is a protecting portion covering an outer and inner surface of the heat-generating t 30 substance 34 to protect it from contact with the .1 0° Bheat-in.ulating and fire-resistant material forming the base plate. The protecting portion 35 may cover the whole surface of the base plate. In Fig. 10, 36 is a ventilation hole which is provided in the groove 33 at each appropriate position and is connected in the groove.

Fig. 11 shows another embodiment in which a protectinq layer 35' comprising sintered carbonized products or oxidized products or a mixture of its I!ne powders is 39 -14- VHF T P 4 formed on a surface of the ignition means 31b, and a line groove 36' is formed along a groove 33 on a lower surface of a castable-made base board 32. The ventilation means prevent cracking of the base plate 32 by absorbing heat in the present invention.

The base board 32 comprises a heat-insulating material conventionally used in an electric board such as diatomaceous earth, clay, alumina cement, etc. Numeral 37 is a lead wire to the heat-generating substance.

Fig. 11 shows an ignition means 31c which is provided in the combustion chamber in a projecting ccndition and has the section of a triangle and is hollowed, On the outer periphery of the ignition means is provided a helical groove in which a heat-generating substance 34 is retained and a protecting layer 35 is formed by filling the groove with heat-resiStance material, and ventilation holes 36 are pierced through the base board. The ignition means 31c is an inmprovement of the ceramic ignition means shown in Fig. 13 (c) j 20 hereinafter described.

The protecting portion 36 comprises heat-resistant castable wiich has heat resistance up to a combustion temperature of 1500 C, and a surface-protecting layer made of conventionally used sintered oxidized ,o substance or its fine powder as shown in Fig. 11 (a) hereinbefore described, whereby the ignition means has a* improved heat resistance.

As shown in Fig. 12, the solid fuels 38 between the ignition means (31a, 31b to 31g) in the combustion chamber 3 and the fuel-holding portion 2 are heated by charging electricity into the ignition means 31a. In the combustiox chamber temperatures rise to produce volatile substances due to heat de'omposition which burn in air.

The atmospheric temperature rises in the combustion chamber as the burning progresses. When the temperature reaches a certain level, the solid fuels 37 reach their ignition point to start to burn by obtaining oxygen. At this time, charging of electricity into the ignition means 39 XA.l

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h. Ai is stopped by using temperature sensors or timers or by observation with the naked eye. When the solid fuels continue to burn and start to become red on the whole to reach high temperature combustion by radiant heat, the solid fuels, in case of the one having low ash content, produce cracks and become fine and scatter around. In such a case, since a stream of air is fed to the inside of the combustion chamber by air absorption from the air absorbing hole, the fine fuels do not fall down or burst out from the air-absorbing space 2a but stay in the combustion chamber at high temperatures and continue to burn.

In the embodiment of Fig. 12, when the ignitiion means 31d is used in place of the ignition means 31a or 31c, the fuel-holding portion 2 is not required, and the ignition means 31d is used in place of the ignition means c c 31a or ?31c, the fuel-holding portion 2 is not required, and the ignition means can be used as such. The ignition ;means 31e in Fig. 11 is of roaster type, which is 20 suitable for fuels having low ash content. In stch S. ignition means, it is possible to use fuels having high ash content by embedding a heat-generating substance 34 into a lattice portion 32 In Fig. 11 a heat-generating substance 31f is of rod shape, and is made into a plane one, such as a heat-generating substance 31g 0" in Fig. 11 by arranging a plural of rod-like Soa 6 substances in a row. The latter is suitable as a cooking o stove for broiling fishes.

The ignitico means as mentioned above may be 30 protected by being surrounded by and reinforced with a metal frame for preventing the mechanical strength of the ignition means from decreasing during a long period of use. Furthermore, the ignition means can be used not only as an ignition means and a fire grate for high calorie solid fuels having low ash content but also as an ignition means and a fire grate for solid fuels having high ash content by including provision for means to easily remove remaining ashes on the ignition means. For example, the 39 -16- VHF n 1 i-

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i means may provide for the downward rotation of the base board 32 from the setting hole la of the base stand 1 or may allow the outward sliding of the base board from the base stand.

The combustion of solid fuels is effected as follows: a fixed amount of solid fuels is charged from the fuel charging lid 8 onto the holding board 5, the fuel being surrounded by the heat-keeping layer 2' of the fuel-holding portion 2 and is accumulated thereon. The heat-generating substance or igniting material on the holding board 5 is heated to heat the solid fuel, which is gradually heated from the lower portion of the fuel. The temperature of the solid fuels is elevated to produce a volatile component from the fuels by heat decomposition.

The volatile component burns in the air in the combustion chamber and at the same time the atmospheric temperature in the combustion chamber rises. When the combustion temperatue and the atmospheric temperature reach a certain o, "level, the igniting material reaches an .gniting point and k 0,C 20 starts to burn by obtaining oxygen in the air introduced from the space 2a.

fet The combustion of the solid fuels spreads to all of the fuel and the accumulated whole solid fuels are heated until it glows red. When the high temperature combustion is brought about in the combustion chamber by radiant heat, the solid fuels crack up to become fine particles.

B Although the smaller pieces of the solid fuels are a a scattered around, they do not fall down from the holding S" board which has a plane shape. Thus, the solid fuels are o 30 retained in the combustion chamber surrounded by the 0 po fuel-holding portion, whereby the complete combustion can S*i be achieved by air absorption, radiant heat and high temperature atmosphere.

The exhaust gas generated by combustion is exhausted through the exhausting pipe 7, while the outer air is an amount in proportion with that of the exhaust gas is introduced into the combustion chamber through the space 2a for introducing air.

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c With progress of combustion, the combustion chamber 3 and the heat-scattering portion 4 are highly heated, and the hot air flows from the combustion chamber into the branched scattering portion 4b and the base portion 4a of the heat scattering portion, whreby the natural convection of air absorption, combustion and air exhaust can be smoothly effected. The fine powdered remnants and unburnt substance falls into the branched scattering portion 4a, and after combustion for a long period of time, they are accumulated therein. Such small amount of the remnants, etc. can be referred from an outlet provided on the front end of the base portion 4a, and therefore there is no fear of discharging harmful soot and dust through the exhausting pipe. The provision of a filter in the exhaust pipe can improve the removal of harmful soot and dust.

With continuation of combustion, since the unburnt substances and ashes remain in the base portion 4a and on the holding board, though in a small amount, they are cleaned as follows: by driving a motor or by hand, the holding board is hung down at one end or at the center, or by operating the operating rod 28 projected out of the °to° I front end of the base stand, the holding board is slided outward by disconnecting the same with the supporting board and inclining the supporting board. Similarly when the combustion is sLopped, the remaining fuels are dropped out of the holding board and contained in a charcoal o O a extinguisher.

0 06 0 00 o 00 So 0 o 0 0 0 0° 0 39 -18- VHF-o p'O iNT0O

Claims (9)

1. A combustion device for solid fuel, including: a base stand with an opening therein, an imperforate heat resistant holding board locatable to close said opening; a combustion chamber standing on the base stand with the holding board at the bottom thereof; a wiper arm pivoted for horizontal wiping movement over the base of the combustion chamber; an inlet means at a lower edge of said chamber above the base) and/or in a surrounding wall of said chamber, whereby combustion air may enter as exhaust gases leave the combustion chamber; an exhaust pipe for the exhaust gases; generally tubular gas-flow heat-exchange ducting putting the combustion chamber and exhaust pipe into communication; and means capable of moving the holding board into or out of the opening for removal of ash or other residue.

2. A combustion device as claimed in claim 1 wherein the holding board is mounted to be pivotable towards or away from the opening in accordance with the movement of a motor-actuable connecting mechanism pivoted at one end to said board.

3. A device as claimed in claim 2 wherein a motor-driven worm gear rotates through a predetermined angle a meshing pinion attached to said connecting mechanism so as to move the board between a closed position within the opening to an open position hanging from its pivot beneath the opening.

4. A combustion device as claimed in claim 1, 2 or 3 in which the wiper arm shares its pivot with an operating arm located at a fixed angle to the wiper arm beneath the base stand, whereby movement of the operating arm moves the wiper arm through its horizontal wiping movement.

A combustion device as claimed in claim 4 wherein a motor driven worm is located to rotate a meshing -19- 7 t cft ft '''ft ft ft I* f ftf I *00 1440 ft I 40r I ft 00 04 I, 0I 0 4 i VHF pinion carrying an actuating arm to move the said operating arm and then release it; and wherein the wiper arm is spring-biased to return to its original position on such release of the operating arm. cotbuasn

6. A S s device as claimed in any one of the preceding claims in which the holding board is supported upon a support plate beneath the base stand, the a plate being connected at one end of the base 1 B and a manually operable operating rod being pivotable to hold or release the support plate in or from the vicinity of the base/qbak and hence move the holding board between a closed position in the opening and the open position beneath the opening.

7. A combustion device as claimed in claim 6 in which the said holding board is capable of sliding in relation to the support plate.

8. A combustion device as claimed in any one of the preceding claims further including electrical ignition t ic means at, or constituting a lower portion of the combustion chamber, including an electrical heating element located in a surface groove or grooves thereof, and protected by a heat-insulating fire-resistant material from .he action of the combustion chamber, said groove or eat. grooves being in communmication with the atmosphere by at least one hole or like opening on a rear face of the ignition means. °o

9. A combustion device as claimed in claim 1 and substantially as herein described with reference to Figures 1 to 12 of the accompanying drawings. .ot DATED: 8 December 1989 0l. 4PHILLIPS ORMONDE FITZPATRICK Attorneys for: DAIHACHIRO MURASE 39 s VHF 0272b