DE2512098A1 - GAS FIRE WITH BIMETALLY CONTROLLED EXHAUST FLAP - Google Patents

Description

Patent Attorneys Dipl.-Jng. R "Weickmann, £ t) I

Dipl.-Ing. H.Weickmann, Dipl.-Phys. Dr. K. Fincke Dipl.-Ing. R A.Weickmann, Dipl.-Chem. B. Huber

8 MUNICH 86, DEN

PO Box 860 820

MÖHLSTRASSE 22, CALL NUMBER 98 39 21/22

CAL

Luitpold Kutzner

8000 Munich 60, Marschner Str. 78

Werner Diermayer ,

1275 Panorama Drive, Lafayette, California 9 ^ -540, V.St.A.

Gas fireplace with bimetal-controlled flue gas flap

The invention relates to a gas-heated fireplace with a flow safety device in the exhaust duct leading to the chimney and with a throttle device comprising a bimetal-controlled flap in the exhaust gas duct at a point located downstream of the flow safety device in the direction of flow, this Throttle device is controlled in such a way that in the entire range of temperatures occurring at the throttle device the cross section released by the throttle device corresponds approximately to the exhaust gas throughput in such a way that the room air is extracted is kept low by the flow protection.

Such a fireplace is known from prior public use in Germany.

In the known fireplace, the throttle device is on the one hand controlled as a function of the temperature at the point of their attachment and on the other hand in direct dependence on the flow velocity at this point. In the

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known fireplace, the aim is to improve the efficiency of the "fireplace:

Efficiency is the ratio of the combustion heat generated in the fireplace to the usable heat used Heat of combustion, i.e. the generated heat of combustion reduced by the amount of heat dissipated through the chimney. It is easy to see that the more room air through the flow protection, the worse the efficiency is deducted.

The problem of improving efficiency has become particularly acute since gas fires, especially space heaters, from the OPEN-CLOSE control with always the same ΰΒεζμΐυΙΐΓ has switched to a sliding control with varying gas supply during OPEN operation, since this sliding control of the amount of exhaust gas also varies, so the flow cross-section of the exhaust gas duct is wide The limits are varied and the extraction of room air by the flow protection is therefore also wide Limits varied up to high values. In addition, the efficiency has been deteriorated because the Manufacturers have switched to designing ovens of different capacities with standardized exhaust gas duct cross-sections. In doing so, the exhaust gas duct cross-section was placed on the furnace with the highest output, which resulted in that in furnaces with a lower output of the exhaust gas does not fill the cross-section and excessive room air through the Flow safety device has been sucked in.

At first glance, the well-known training seems to be the exact answer to the problem of improving efficiency to be by reducing the room air exhaust via the flow protection; however, occur in the practical implementation great difficulty. The main difficulty lies in that the control of the throttle device depending on the chimney draft with very low static and dynamic Pressures as a control variable have to get by, which is very sensitive

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Control mechanisms suspended, corresponding to liver sensitivity are also susceptible to failure.

The invention is based on the object of a gas fireplace of the type described at the beginning, avoiding structurally complex and failure-prone control in immediate depending on the chimney draft so that the room air extraction remains low in the entire operating area so that there is a good level of efficiency in the entire operating range.

To solve this problem, it is proposed according to the invention that the throttle device be exclusively by the on-site their attachment in the exhaust duct is controlled temperature and that the throttle device by measures to Influencing the temperature curve of the throttle cross-section in this way on the furnace-specific curve of the exhaust gas throughput in Dependence on the temperature measured at the glandular device it is set so that a small residual flow of room air is guaranteed through the flow safety device, that of the chimney draft dependent flow rate the throttle device in the sense of a reduction of the throttle cross-section with increasing chimney draft and vice versa.

It is also known to have bimetal-controlled exhaust flaps without additional ones Influence directly dependent on the chimney draft to be used in gas-fired fireplaces. The bimetal-controlled valves are essentially just the puncture intended, the fireplace in the inoperative state of the chimney in the sense of preventing the room from being cooled down by the chimney vent to separate and on the other hand to release the flue gas duct when the fireplace is put into operation. Of course it opens Even in these known devices, the bimetallic flap continuously depending on the prevailing at its point of attachment Temperature and of course, in these devices too, the bimetal flap is influenced by the flow safety device To expect sucked in room air in the sense that when the chimney draft increases, more room air is sucked in, this

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Room air the total flow at the point of the bimetal damper cools down and closes the bimetal flap further. So far, no attempt has been made to use the bimetal valve as a control device to train in the sense that the temperature profile of their throttle cross-section corresponds to the temperature profile of the exhaust gas corresponds to the respective furnace type, and above all, it has not been recognized that when you adjust the temperature response of the Throttle cross-section to the temperature curve of the exhaust gas (temperature measured at the location of the bimetal flap) A control is achieved solely by using the cooling effect on the bimetal flap resulting from the room air extraction, the keeping of the room air exhaust and thus an improvement of the efficiency in the with the behavior of the Known device described at the outset enables comparable scope. While the known device described above based on the consideration that the room air extraction through the flow protection is normally harmful and avoided must be, the solution according to the invention is based inter alia on the opposite consideration, namely that the room air extraction through the flow protection, if you allow it to a limited extent, for indirect control of the throttle device in Depending on the chimney draft can be used.

The adaptation of the temperature response to the throttle cross-section to the temperature response of the exhaust gas can be done, for example take place in that within the surface of the bimetallic valve at least one of the surface of the valve pivotable bimetal-controlled partial flap is arranged. With this measure it can be achieved that in the lower Temperature range, the effective throttle cross-section increases rapidly, since in addition to the throttle cross-section released by the flap between the flap edges and the exhaust duct walls, cross-sectional areas within the area of the flap be released. Naturally, these additional openings are particularly significant in percentage terms when the flap is still close to its closed position while

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they practically no longer play a role if the flap is essentially parallel to the direction of flow and thus in their open position.

Depending on the design of the flap, the respective partial flap can be arranged in such a way that its pivoting movement is in the same direction with the flap or in the opposite direction to its pivoting movement.

Another measure to adapt the temperature response of the throttle cross-section to the temperature response of the exhaust gas can consist in the fact that the effective throttle cross-section corresponding to a certain partial pivoting range of the flap is reduced by cover surfaces which, within this partial pivoting area, are affected by the flap edges during the pivoting movement at least approximately touch the envelope surfaces defined on the flap. With a corresponding shape and arrangement The temperature response of the throttle cross-section can be adapted very precisely to these cover surfaces over a wide range. The cover surfaces can be arranged, for example, so that they have a part of the through the in the lower temperature range Cover the opening of the flap against the throttle cross-section arising from the exhaust gas duct walls. The cover areas can, however also be arranged so that they touch the envelope surfaces generated by the flap edges in an area or them come close, which corresponds to a valve position at medium to high temperatures. This means that the increase in Throttle cross-section can be reduced or made zero with increasing temperature. It is even possible to have a decrease to achieve the throttle cross-section with increasing temperature.

It is of course possible to combine the above-mentioned measures with one another.

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The accompanying figures explain the invention on the basis of exemplary embodiments. They represent:

Fig. 1 is a perspective view of a first known Exhaust flap with four bimetallic controls each covering one quadrant of the exhaust gas duct cross-section Flap wings,

FIG. 2 shows a schematic axial section through eira according to FIG Invention modified exhaust flap according to Fig. 1 along the line H-II in Fig. 1,

3 to 8 three further variants according to the invention of the exhaust flap according to FIG. 1, each in a section according to FIG. 2 and a plan view in the axial direction,

9 shows a second exhaust flap in a perspective illustration and

Fig. -10 a third exhaust flap in one to the pivot axis the flap normal cut.

In the exhaust flap shown in FIG. 1, generally designated 10, there is a tubular sleeve 12 with a circular cross-section by four webs 14 meeting in the pipe axis divided into four quadrants, each of which is covered by a valve wing 16. The flap wings 16 are made each of a thin bimetal sheet, which is divided by slots 18 into strips 20 connected to the circumference of the sheet is.

On each web 14 one of the flap wings 16 is along one Its edges are fixed in such a way that in the stretched state, i.e. at the highest possible temperature, it is flat on the respective web 14 is present. In this position, the flap wings 16 give the entire cross section of the tubular sleeve 12, i.e. the cross section

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of the exhaust gas duct of the gas fireplace free, in which the exhaust flap 10 between a flow safety device and the chimney is built in. When the gas fireplace is switched off and thus in a cold state, the flap blades 16 are out of plane the webs 14 curved towards the inner wall of the tubular sleeve 12, wherein the to the inner wall of the tubular sleeve 12 pointing edges 22 of the flap wings 16 are formed so that the Flap wing 16 practically rest against the inner wall and the Block the pipe cross-section at this point. The second free Edge 24 of each flap wing 16 moves when the flap wing 16 is pivoted in the plane of the web 14, which together with the web 14 supporting the respective flap wing 16 defines the respective quadrant. The each in The edge 26 of the webs 14 pointing towards the direction of flow (arrow A) is designed so that it conforms to the curvature of the associated flap wing 16 corresponds in its closed position and thus essentially in this position of the flap wing 16 runs parallel to the edge 24 of the flap wing 16. Will If the exhaust flap 10 according to FIG. 1 is heated, the flap blades 16 swivel due to their bimetallic property on the Level of the respective carrier web 14 and give a passage cross section between the edges 24 and 26 or between the edge 22 and the inner wall of the tubular sleeve 12 for passage the exhaust gases and the room air drawn in from the chimney at the same time as the exhaust gases. The position changes the flap wing 16 only on the basis of their temperature, regardless of whether there are a lot or little exhaust gases at this temperature. However, the temperature profile of the exhaust gas is different from gas furnace to gas furnace and subsequently changes to the exhaust flap shown in Fig. 1 are described with which the temperature profile of the passage or Throttle cross-section of the exhaust flap 10 adapted to the temperature range of the exhaust gas accumulation of a certain gas fireplace can be.

In the embodiment according to FIG. 2, the web is shown 14 'extended in the direction of arrow A so that its edge 26'

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is no longer congruent with the edge 24 of the associated flap wing 16 in its closed position. How one the course of the edge 24, shown in dashed lines, in different opening positions of the flap wing 16 can be seen, is now in the lower and middle temperature range (small opening of the flap wing 16) between The passage cross-section for the exhaust gases resulting from the edges 26 'and 24 compared to the embodiment according to FIG. 1 considerably reduced. This means that this embodiment is particularly suitable for a gas fireplace which the amount of exhaust gas is relatively low at low temperatures. The course of the edge 26 "of the web 14" in Figure 3 shows that the edges 26 of the webs 14 can be shaped as desired within certain limits in order to achieve an exact adaptation of the To enable temperature variation of the passage cross-section to the temperature variation of the exhaust gas.

In Fig. 3 there is still another possibility for changing the temperature profile of the passage cross-section shown. The web 14 ″ shown in FIG. 3 has an opening 28 which is formed by a bimetallic flap trained partial flap 30 is closable. When the gas fireplace is switched off, the partial flap 30 is in the Level of the web 14 "and curves out of the plane of the web 14" as the temperature rises, as the dashed line Lines in Fig. 4 show. This change measure also comes mainly in the lower and medium temperature range to advantage, since in the upper temperature range the opening 28 through the open one attached to the web 14 ″ Flap wing 16 is closed. Since the passage cross section through the opening 28 is initially enlarged, it is suitable Such a modified exhaust flap 10 is primarily for gas fireplaces where the exhaust gas is generated low and medium temperatures is already relatively high. Even if the extension of the web 14 and the attachment a partial flap 30 in the web 14 ″ in principle counter-rotating They can nevertheless represent measures under certain circumstances

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can be combined with one another in order to adapt the temperature curve of the exhaust gas accumulation over a larger one To achieve temperature range with the desired gradation.

FIGS. 5 and 6 show a modification of the principle shown in FIGS are provided in the flap wings 16, which can be closed by partial flaps 34 designed as bimetal flaps are. As can be seen from FIG. 5, the bimetal flaps 34 can be designed in this way and on the flap wings 16 arrange that they rotate in the opposite direction with the pivoting movement of the respective flap wing 16 Swing out of the surface of the respective flap wing 16. Also through these constructive measures an enlargement of the passage cross-section is achieved at low and medium temperatures while the opening 32 is irrelevant at high temperatures, i.e. when the flap blades 16 are practically parallel to the direction of flow more plays. Of course, openings 32 and partial flaps 34 can also be found on the other two flap wings the exhaust flap 10 according to FIG. 6 can be arranged.

It is conceivable that the amount of exhaust gas remains approximately the same or even in a certain temperature range decreases with increasing temperature at least over a certain temperature range, i.e. it may be necessary be that the effective passage or throttle cross-section continues despite the increasing temperature opening flap wing 16 is kept constant or even reduced. This can be done, for example, by covering surfaces can be achieved, which represent, for example, parts of a dome that of the edge 22 of a flap wing 16 corresponds to the enveloping surface described during its pivoting movement. In this one on the left side the case illustrated in FIGS. 7 and 8 is, for example, the flap wing 16 in the medium temperature range, in FIG

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which it has with its edge 22 on the dome strip 36 is present, only an effective passage cross-section free, which is essentially an opening point of the flap wing 16 at low temperatures. The effective passage cross-section is only increased again, when the flap wing 16 protrudes with its edge 22 from the area of the dome strip 36.

As the respective right-hand sides of FIGS. 7 and 8 show, the cover surface does not necessarily have to lie in the envelope surface described by the edge 22, but rather can, like the cover surface 38 on the right-hand side of FIGS. 7 and 5, gradually adjoin this envelope surface in its course approach so that the passage gap between the edge and the cover surface when the flap wing 16 is opened gradually decreased.

Of course, the measures described above can be combined in any way and for two or be provided for all four quadrants.

With the exception of the modification of the webs 14, the structural measures described can also be applied to an exhaust flap, which has not four, but only two bimetallic flap wings, one on both sides of which lies in a circle diameter Web are attached and each cover half of the circular cross-section.

The known exhaust flap shown in FIG. 9 comprises a substantially rectangular frame 39 with a rectangular one Frame opening 40 and with attached to the longitudinal sides of the frame 38 bimetallic tongues 42 and 44, here in a slightly open position are drawn. On one side of the frame 39 is an asbestos mask 46 with a circular opening to adapt the exhaust flap attached to a circular exhaust duct.

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The structural changes described above can also be carried out in this exhaust flap. With the dashed Line 50 indicates, for example, a web which is attached to the rectangular frame 39 and in a lower one Temperature range, the passage cross-section between a frame edge 52 of the frame opening 40 and this frame edge 52 adjacent edges 55,57 of the tongues 42 and 44 closes. It would also be conceivable, for example on the longitudinal edges 59.61 cer middle tongues 42 perpendicular to the tongue plane To arrange webs, which in turn a part of the opening of the bimetallic tongues 42, 44 through cross-sections cover. Just as in the surfaces of the flap wings 16, additional tongues 42 can also be used in dashed lines in the bimetal tongues indicated bimetallic flaps 53 may be arranged, which are effective in the lower and middle temperature range Increase the passage cross-section.

The third exhaust flap sketched in FIG. 10 again comprises a rectangular frame 54 with a rectangular one Frame opening 56, which can be closed by a rectangular flap 58. This flap 58 is spiral over two curved bimetal strips 60 within the frame opening 56 around a perpendicular to the plane of the drawing Pivot axis pivotably mounted, each of the bimetallic strips 60, of which only one is shown here, with one end to the flap 58 and the other end to the frame 54 via a bracket 62. Even in this embodiment, all structural changes and additions described with reference to FIGS. 2 to 8 are included can be used to reduce the effective passage cross-section. For example, number 64 denotes a Cover surface which is curved so that the flap 58 at a higher temperature, i.e. at a larger opening angle of this surface 64 with its in the direction of view of FIG. running edge 66 gradually approaches, so that the gas flow around the edge 66 is prevented. On the other hand

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For example, the passage of gases through the edge 68 of the flap 58 which is parallel to the plane of the drawing is described Level can be prevented by the arrangement of a ridge 70 shown in dashed lines. And finally, of course, you can arranged within the surface of the flap 58 bimetallic partial flaps 72 be, which open further opening cross-sections even at low temperatures.

The present statements show that the measures according to the invention for adapting the temperature response of the Passage cross-section of bimetal-controlled exhaust flaps to the temperature range of the exhaust gas accumulation on exhaust flaps different constructions can be used and, taken alone or in combination, offer a wealth of possibilities, to adapt the flue gas flap of the respective gas fireplace with simple means so that its efficiency, especially at Operation of the gas fireplace in the lower and medium output range is essential can be improved.

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Claims (2)

Claims 1. ) Gas-heated fireplace with a flow safety device in the flue gas duct leading to the chimney and with a throttle device comprising a bimetal-controlled flap in the flue gas duct at a point located in the direction of flow behind the flow safety device, this throttle device being controlled in such a way that in the entire area of the throttle device occurring temperatures the cross-section released by the throttle device approximately corresponds to the exhaust gas throughput in such a way that the room air extraction is kept low by the flow safety device, characterized in that the throttle device (10) is controlled exclusively by the temperature prevailing at the location of its installation in the exhaust gas duct and that the Throttle device (10) is set by measures to influence the temperature curve of the throttle cross-section in such a way on the furnace-specific course of the exhaust gas throughput as a function of the temperature measured at the throttle device (10) The fact is that a small residual flow of room air is guaranteed by the flow safety device, the flow rate of which, depending on the chimney draft, influences the throttle device (10) in the sense of reducing the throttle cross-section as the chimney draft increases and vice versa. 2. Gas-heated fireplace according to claim 1, characterized in that that within the surfaces of the bimetal controlled flap (16, 42, 58) at least one of the surface of the flap (16, 42, 58) swing-out bimetal-controlled partial flap (34, 53, 72) is arranged. 609842/0378 Gas-heated fireplace according to claim 1 or 2, characterized in that shows that the effective throttle cross-section corresponding to a certain partial pivoting range of the flap (16, 42, 58) is reduced by cover surfaces (14 ', 36, 38; 50; 70, 64) which, within this partial pivoting area, are those of the flap edges (24, 22; 55, 57; 68, 66) at least defined enveloping surfaces during the pivoting movement of the flap (16, 42, 58) approximately touch. 609842/0378 4S Blank page