Stove

Abstract

A stove for indoor use includes a housing having a bottom wall, a top wall and one or more side walls defining a combustion chamber adapted to retain a fire, and an air supply system for supplying air to the combustion chamber. The air supply system includes a primary air conduit for supplying air to the combustion chamber from below through the bottom wall and a secondary air conduit for supplying air to the combustion chamber from above. A valve is arranged in the primary air conduit or in a branching between the primary and secondary air conduits. The valve is controlled by a bimetal whereby the valve is in a maximum open position when the prevailing temperature is below a first predetermined temperature during start-up of a fire and in a maximum closed position when the prevailing temperature is above a second predetermined temperature after start-up of the fire.

Claims

1. A stove adapted for indoor use, the stove comprising a housing having a bottom wall, a top wall and one or more side walls defining a combustion chamber adapted to retain a fire, an air supply system for supplying air to the combustion chamber, the air supply system comprising a primary air conduit for supplying air to the combustion chamber (40) from below through the bottom wall, a secondary air conduit for supplying air to the combustion chamber from above, wherein the primary and secondary air conduits are connected to a common inlet, wherein the air supply system further comprises a valve arranged in the primary air conduit or in a branching between the primary and secondary air conduits, wherein the valve is controlled by a bimetal which is affected by prevailing temperature in the stove, wherein the bimetal controls the valve such that the valve is in a maximum open position when the prevailing temperature is below a first predetermined temperature during start-up of a fire and in a maximum closed position when the prevailing temperature is above a second predetermined temperature after start-up of the fire, whereby the air flow will in the maximum closed position of the valve be supplied exclusively or to a greater extent from above the fire compared to when the valve is in the maximum open position, wherein the first predetermined temperature is lower than the second predetermined temperature.

2. Stove according to claim 1, wherein the first predetermined temperature is between 30-65° C., preferably between 35-50° C.

3. Stove according to claim 1, wherein the second predetermined temperature is between 80-120° C., preferably between 80-110° C.

4. Stove according to claim 1, wherein the first predetermined temperature is at least 10° C. lower, more preferably at least 20° C. lower, and most preferably at least 30° C. lower, than the second predetermined temperature.

5. Stove according to claim 1, wherein the common inlet has an area of between 3-10 times an open area of the valve in its maximum open position.

6. Stove according to claim 1, wherein an open area of the valve in its maximum closed position is less than 10% of the open area of the valve in its maximum open position, preferably less than 5%, and most preferably 0%.

7. Stove according to claim 1, wherein the primary air conduit connects to the combustion chamber via a plurality of openings in the bottom wall, wherein the openings have a total area of between 1.1 and 5 times, preferably between 1.3 and 3 times an open area of the valve in its maximum open position.

8. Stove according to claim 1, wherein the valve is a pinwheel air damper.

9. Stove according to claim 1, wherein the bottom wall comprises a grate assembly comprising a first grate part, and a second grate part, wherein the first grate part is movable in a direction of movement relative to the second grate part, wherein the first grate part and the second grate part both extend in an essentially horizontal direction with the second grate part underlying the first grate part in a vertical direction of the stove, wherein the second grate part comprises a downwardly extending groove extending along the direction of movement and being intermittently interrupted along the direction of movement by through-going openings, and wherein the first grate part comprises a plurality of through-going openings, each through-going opening partly overlying the groove and thereby providing a plurality of channels for a flow of primary air from below via the through-going openings and obliquely along the groove of the second grate part and via the through-going openings of the first grate part up to the combustion chamber.

10. Stove according to claim 9, wherein the first grate part further comprises an ash scraper extending into the groove of the second grate part, whereby movement of the first grate part along the movement direction will cause the ash scraper to move along the groove and scrape any ash in the groove out of the groove and into the through-going openings interrupting the groove.

11. Stove according to claim 10, wherein the through-going openings of the first grate part are provided with sidewalls extending downwardly to an upper surface of the second grate part thereby forming a top open compartment with a bottom formed by the upper surface of the second grate part.

12. Stove according to claim 11, wherein one of the sidewalls of the through-going openings of the first grate part extend into the groove thereby forming the ash scraper and an opposing one of the sidewalls of the through-going openings of the first grate part extending above the groove thereby forming an opening for the obliquely oriented flow along the groove.

13. Stove according to claim 9, wherein the first grate part is rotatable about a centre axis extending along a normal of a portion of the bottom wall formed by the first and second grate parts.

14. Stove according to claim 13, wherein the groove extend along an arc around the centre axis.

15. Stove according to claim 9, wherein the first grate part is manually operated to be moved relative to the second grate part, wherein the stove further comprises a valve for additional supply of air from below, the valve being operably connected to the operation of the first grate part for opening and closing of the valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting description of currently preferred embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements.

[0043] FIG. 1 is a perspective view from below of a stove.

[0044] FIG. 2 is a perspective view from below of the air supply control system.

[0045] FIG. 3a is a view from above of the air supply control system in a partly closed position.

[0046] FIG. 3b is a view from above of the air supply control system in a fully open position

[0047] FIG. 4 is a cross-section showing the air conduits in the stove

[0048] FIG. 5 shows details of a valve in a primary conduit.

[0049] FIG. 6a shows in an exploded view a grate located at the bottom of the combustion chamber

[0050] FIG. 6b shows the grate in assembled state.

DETAILED DESCRIPTION

[0051] As shown e.g. in FIG. 1 and FIG. 4 the stove 1 adapted for indoor use comprises a housing having a bottom wall 10, a top wall 20 and one or more side walls 30a-d defining a combustion chamber 40 adapted to retain a fire. The stove 1 also comprises an air supply system 50 for supplying air to the combustion chamber 40.

[0052] The air supply system 50 comprises a primary air conduit 60 for supplying air to the combustion chamber 40 from below through the bottom wall 10 and a secondary air conduit 70 for supplying air to the combustion chamber 40 from above.

[0053] The primary and secondary air conduits 60, 70 are connected to a common inlet 61, The size of the common inlet 61 is adjustable. As shown in FIGS. 1, 2, 3a and 3b the size of the opening 62 of the common inlet 61 may be manoeuvred to be fully or partly covered, such as with a throttle or valve plate 63. The valve plate 63 is manually operable. This is accomplished by a lever 64 which interacts with an arm 63b attached to the plate 63. The lever 64 is pivotable about a centre axis 65 such that the arm 63b and the plate 63 is moved to open or close the opening 62 when the lever 64 is manoeuvred by the use of a handle 66 positioned at the, relative to the arm 63b, opposite end of the lever 64.

[0054] The air supply system 50 also comprises a tertiary air conduit 80 for supplying air to an upper portion of the rear wall 30a.

[0055] The tertiary air conduit 80 is connected in parallel with the common inlet 60. Both the tertiary conduit 80 and the common inlet 60 are connected to a common main inlet 90. The tertiary air conduit 80 may but is not provided with any throttle or valve. However, when the user manoeuvres the valve plate 63 towards a more closed position a greater amount of air will prefer to enter into the tertiary conduit 80.

[0056] The tertiary air conduit 80 ends at the upper portion of the rear wall 30a with a plurality of small nozzles 81.

[0057] The tertiary air conduit 80 has an entrance opening with a cross-sectional area of about 300-400 mm.sup.2. The total cross-sectional area of the nozzles 81 is about 50-150 mm.sup.2. The opening 62 has a maximum open cross-sectional area of about 2000-3000 mm.sup.2. The main inlet 90 has a cross-sectional area of about 3000-4000 mm.sup.2.

[0058] The air supply system 50 also comprises a valve 51 arranged in the primary air conduit 60 or in a branching between the primary and secondary air conduits 60, 70.

[0059] In FIGS. 4 and 5 it is shown that the common inlet 61 leads into a box shaped volume 67 which extends below the bottom wall 10 along the rear side of the stove 1. The valve 51 is arranged in the wall of the box shaped volume 67 facing the volume 11 underneath the bottom wall 10. The secondary conduit 70 connects to the box shaped volume by large openings in the rearward facing walls of the box shaped volume 67.

[0060] The valve 51 is controlled by a bimetal body or blade 52 which is affected by prevailing temperature in the stove 10. The bimetal 52 controls the valve 51 such that the valve 51 is in a maximum open position when the prevailing temperature is below a first predetermined temperature (T1) of about 40° C. during start-up of a fire. When the bimetal reaches about 40° C. it will start to close the valve 51. The bimetal 52 controls the valve 51 such that the valve 51 is in a maximum closed position when the prevailing temperature of the bimetal 52 is above a second predetermined temperature (T2) of about 90-100° C. after start-up of the fire.

[0061] The valve 51 may be a so-called pinwheel air damper. Such a valve 51 has typically a first hole pattern in a first part 53 and a second, typically similar, hole pattern in a second part 54. The hole patterns are typically shaped as elongate openings extending radially about a central axis about which one of the two parts is rotatable relative to the other. As shown in FIG. 5, the bimetal 52 is at one end 52a fixed relative to one of the parts 53 and interacts at its other end 52b with the rotatable plate 54, such as via a pin 54b attached to the plate 54.

[0062] The valve 51 is shown in FIG. 5 in its open position. The plate 54 is urged in a counter clock wise rotation by a tension spring 55. The plate 54 has a protrusion 54a interacting with a pin 53a providing a stop against the force from the tension spring 55.

[0063] The pinwheel air damper 51 is designed such that adjacent holes in the hole pattern are separated by at least 45°, preferably at least 75°. Thereby it is possible to allow the bimetal to deform substantially at still preventing that the pinwheel air damper starts to open again due to excessive movement of the plate 54 such that a hole starts to overlap with the next hole of the hole pattern of the fixed part 53. This way of preventing the pinwheel air damper 51 from reopening when the temperature increases is desirable since there is in such a case no need for any stop-pin or disconnection between the plate 54 and the bimetal 52. However, such designs are of course also conceivable. In the shown embodiment the valve 51 is completely closed in its maximum closed position.

[0064] As shown in FIGS. 4, 6a and 6b, the bottom wall 10 comprises a grate assembly 100 comprising a first grate part 110 and a second grate part 120. The first grate part 110 is movable in a direction M of movement relative to the second grate part 120 by being rotatable about a centre axis A extending along a normal N of a portion of the bottom wall 10 formed by the first and second grate parts 110, 120.

[0065] As shown in the figures, the first grate part 110 and the second grate part 120 both extend in an essentially horizontal direction with the second part 120 underlying the first part 110 in a vertical direction V of the stove 1.

[0066] The second grate part 120 comprises a downwardly extending groove 121 extending along the direction M of movement and being intermittently interrupted along the direction M of movement by through-going openings 122. The groove 121 extends along an arc around the centre axis A.

[0067] The first grate part 110 comprises a plurality of through-going openings 112, each through-going opening 112 partly overlying the groove 121 and thereby providing a plurality of channels 123 for a flow 61b of primary air from below via the through-going openings 122 of the second grate part 120 and obliquely along the groove 121 of the second grate part 120 and via the through-going openings 112 of the first grate part 110 up to the combustion chamber 10.

[0068] The first grate part 110 further comprises an ash scraper 113 extending into the groove 121 of the second grate part 120. Movement of the first grate part 110 along the movement direction M will cause the ash scraper 113 to move along the groove 121 and scrape any ash in the groove 121 out of the groove 121 and into the through-going openings 122 interrupting the groove 121.

[0069] As shown in FIGS. 6a and 6b, the through-going openings 112 of the first part 110 are provided with sidewalls 114a-d extending downwardly to an upper surface of the second grate part 120 thereby forming a top open compartment with a bottom formed by the upper surface of the second grate part 120.

[0070] As shown in the enlargement of FIG. 6b, one of the sidewalls 114d of the through-going openings of the first part 112 extend into the groove 121 thereby forming the ash scraper 113 and an opposing one of the sidewalls 114c of the through-going openings 112 of the first part 110 extending above the groove 121 thereby forming an opening 123 for the obliquely oriented flow 61b along the groove 121.

[0071] The primary air conduit 61 connects to the combustion chamber 40 via a plurality of openings 123 in the bottom wall 10, wherein the openings 123 have a total area of between 1.1 and 5 times, preferably between 1.3 and 3 times an open area of the valve 51 in its maximum open position. The total area of the openings 123 is about 700-1100 mm.sup.2, preferably about 900 mm.sup.2.

[0072] The first grate part 110 is manually operated to be moved relative to the second grate part 120 using a handle 115 and lever assembly 116. The handle 115 and lever 116 is shown in FIG. 1. The top part of the lever 116 is shown in FIG. 5. As shown in FIG. 1, when the handle 115 is drawn outwardly it will pivot about attachment point 116a and will thereby draw the lever 116 along the long hole 116b. The part of the lever 116 shown in FIG. 5 interacting with the first grate part 110 will thereby cause the first grate part 110 to rotate about 10-15° about the centre axis A in the counter clockwise direction such that the ash scrapers 113 scrape ash from the groove 121.

[0073] The stove 1 comprises a valve 130 for additional supply of air from below. The valve 130 is operably connected to the operation of the first grate part 110 for opening and closing of the valve 130. In FIG. 5, it is shown how a wire 121 is connected to the lever arm 116. When the user operates the handle 115 to rotate the first grate part 110, the lever 116 is moved, in the figure towards the handle 115. Thereby will the lever 116 tug the wire 131 and will thereby open the latch 130 forming the valve. The latch 130 is spring-loaded by springs 132 towards the closed position.

[0074] The person skilled in the art realizes that the present invention by no means is limited to the embodiment described above. For instance the fireplace may have another configuration and dimensions.

[0075] It may also be noted that in one embodiment, the stove is provided with the bimetal controlled valve but is not provided with the grate assembly. In another embodiment, the stove is provided with the grate assembly but is not provided with the bimetal controlled valve. In one embodiment the stove is provided with the grate assembly and the valve operably connected to the operation of the first grate part but is not provided with the bimetal controlled valve. In a preferred embodiment, the stove is provided with the bimetal controlled valve and with the grate assembly. In a preferred embodiment, the stove is provided with the bimetal controlled valve, the grate assembly and the valve operably connected to the operation of the first grate part.