DESCRIPTION

The invention relates to a gas hearth, at least comprising a combustion chamber, gas supply means for supplying combustible gas into the combustion chamber to firebed-simulating means positioned in the combustion chamber, ignition means for igniting the combustible gas in the combustion chamber and a flue-gas discharge duct connected to the combustion chamber for discharging combustion flue gases from the combustion chamber, as well as metering means which are arranged in the combustion chamber for metering a pyrotechnical additive into the flames of the burning combustible gas during operation, wherein the metering means comprise a reservoir for the pyrotechnical additive which reservoir is provided with at least one metering opening.

Various types of hearths, in particular decorative hearths, are known, many of these hearths can be used as built-in hearths or as hearth stoves. Such decorative hearths are suitable for burning gas, wood or other natural fuels. A decorative gas hearth according to the above introduction is known from, for example, EP3273163A1. The metering means meter a pyrotechnical additive into the flames of the burning combustible gas during operation, thus creating an additional fire impression, i.e. sparks which also occur with the burning of real wooden logs.

Although metering means as implemented in the decorative gas hearth of EP3273163A1 provide a very realistic impression of a fire resembling the burning of real wooden logs, the process of metering the pyrotechnical additive into the flames can be further improved, thus guaranteeing an improved control of the metering of pyrotechnical additive added to the flames, both in amount as in time, and thus further improving the gas fire image resembling the burning of actual wooden logs as realistic as possible.

It is therefore an object of the present invention to provide a gas hearth according to the abovementioned preamble with an improved metering of pyrotechnical additive into the flames, thus providing a more realistic impression of a fire resembling the burning of real wooden logs.

To this end, the metering means comprise displacement means positioned in the reservoir for displacing the pyrotechnical additive contained in the reservoir towards and through the at least one metering opening. With the implementation of displacement means in the reservoir, which displacement means proactively displace a certain amount of pyrotechnical additive towards and through the metering opening for metering into the flames of the burning combustible gas an improved control, both in amount as in time, can be achieved and thus an improved gas fire image resembling the burning of actual wooden logs as realistic as possible is created.

In particular the displacement means comprise a rotatable driven screw conveyor. Such rotatable driven screw conveyor provides a reliable supply of pyrotechnical additive towards and through the metering opening for metering into the flames of the burning combustible gas.

In an example the metering means comprise at least one supply line which is connected to the metering opening and ends near the firebed-simulating means. To this end, it is possible to install the metering means elsewhere in the gas hearth and not necessarily in the combustion chamber, which is not desirable from an aesthetic and safety point of view.

Additionally, the metering means comprise at least one pump which is placed near the at least one metering opening for passing a certain amount of displaced pyrotechnical additive through the supply line in the direction of the firebed-simulating means by means of a pressurized medium.

In a further example, the metering means comprise control means for actuating the displacement means and the pump. With this embodiment it is possible to proactively control, both in amount as in time, the metering of pyrotechnical additive towards and through the metering opening into the flames of the burning combustible gas thus improving the resemblance of actual wooden logs as realistic as possible.

Preferably the pump is a compressed air pump.

The metering means may be arranged under the firebed-simulating means.

In a further embodiment, the reservoir is provided with a filling opening which can be closed with a closure, which closure, in the embodiment wherein the metering means have been arranged under the firebed-simulating means, forms part of the firebed-simulating means.

Furthermore, the pyrotechnical additive may consist of granules, for example a pulverulent or granular material, in particular a carbon-containing additive.

The invention will now be explained in more detail with reference to a drawing, in which successively:

Fig. 1 shows a diagrammatic view of an embodiment of a gas hearth provided with metering means for metering a pyrotechnical additive according to the prior art; Fig. 2 shows a diagrammatic view of another embodiment of a gas hearth provided with metering means for metering a pyrotechnical additive according to the prior art;

Figure 3 an example of a gas heart having improved metering means;

Figure 4a a detailed view of an embodiment of metering means;

Figure 4b a further detailed view of an embodiment of metering means;

Figure 4c another embodiment of metering means;

Figures 5a-5b another views of an embodiment of the metering means.

For a better understanding of the invention, the similar components shown in the various figures are denoted by identical reference numerals in the following description of the figures.

Fig. 1 diagrammatically shows an embodiment of a gas hearth according to the prior art. In particular, the burner system of a hearth is shown in the way in which it is arranged in the combustion chamber of the gas hearth.

In general, a decorative hearth is composed of a housing comprising side walls, a bottom wall, a front wall and a rear wall. The front wall is often transparent and can also be rotated away or slid away for maintenance. The front, bottom, rear and side walls enclose a combustion chamber 10 in which the firebed-simulating means, denoted here, for example, by reference numerals 12a-12d, are accommodated. The firebed- simulating means 12a-12d are configured to simulate a fire image and all respective components are fitted to a bottom panel which forms part of the bottom wall of the combustion chamber 10.

As is illustrated in Fig. 1, the hearth 1 is provided with gas supply means (gas supply line) 13 which are connected to a main supply line (not shown). The gas supply line 13 branches off into branch lines 13a-13d, each of which extend into the combustion chamber 10, and which, in particular, each end at the location of the firebed- simulating means 12a-12d. A control valve 14 is incorporated in the gas supply line 13 which can be controlled by suitable control means (not shown) via the control line 15 and can be closed off in order to close off the gas supply into the combustion chamber 10.

The firebed-simulating means 12a-12d may be configured, for example, as imitation logs, which may, for example, be made of a fireproof ceramic material. Such imitation logs are often also porous, so that the gas supplied via the respective branch line 13a-13d may flow through or leak into the porous imitation logs and can be made to ignite locally on the surface using suitable, gas ignition means (not shown). In this way, a fire image may be simulated which is similar to that of a conventional fire of burning wooden logs.

The combustion flue gases can be discharged from the combustion chamber 10 via the flue-gas discharge duct 11.

As the primary objective of a decorative hearth is to produce a realistic fire image and is not intended - unlike conventional hearths - to emit heat to the surroundings, it is desirable for a decorative hearth to produce as realistic a fire image as possible while using a minimal amount of gas.

However, a lower gas consumption (i.e. gas supply to the combustion chamber via the gas supply 13) also leads to fewer flames, as a result of which the fire image is less realistic. However, the firebed-simulating means 12a-12d aim to enhance the fire image by simulating burning logs.

In order to be able to also produce a realistic fire image with an improved fire impression in the case of reduced gas consumption, metering means 20 are arranged in the combustion chamber 10 which, during operation, meter a pyrotechnical additive into the flames of the burning combustible gas. In particular, the metering means are arranged above the firebed-simulating means 12a-12d, as is illustrated in Fig. 1, in such a way that, when metering the pyrotechnical additive being contained in reservoir 22 via the metering opening 22b, this additive ends up in the air stream of the rising combustible flue gases and is ignited by the flames when it flutters down in the direction of the firebed created by the firebed-simulating means 12a-12d. Upon ignition, the pyrotechnical additive generates additional fire and light effects, such as sparks, which also occur during burning of natural wooden logs.

In another example, such as illustrated, for example, in Fig. 2, the metering means 20 are arranged at the bottom of the combustion chamber 10 and more particularly under the firebed-simulating means 12a-12d. Reservoir 22 is provided with a metering opening 22b for supplying a certain amount of pyrotechnical additive from the reservoir 22 to a supply line 27-25 which runs from the metering opening 22b through the combustion chamber and the free end 25a of which ends at one of the firebed-simulating means 12a-12d.

With reference to Figures 3 and 4a, 4b and 4c, an example of a gas hearth according to the invention is described. Also in these Figures reference numeral 22 indicates a reservoir wherein a certain amount of pyrotechnical additive is stored. The reservoir 22 has to be sufficiently fire-resistant and heat-resistant in order to ensure that the heat which is produced in the combustion chamber during operation does not result in an undesirable and premature spontaneous combustion of the pyrotechnical additive which is held in the reservoir 22.

The reservoir 22 is provided with a top side 22a which is provided with an opening which may be closed off by a closure, in particular a closing lid 23. The reservoir 22 can be filled with a certain amount of pyrotechnical additive via the opening which is provided in the top side 22a. Furthermore, the reservoir 22 is provided with a metering opening 22b for supplying a certain amount of pyrotechnical additive from the reservoir 22 to a supply line 25 which runs from the metering opening 22b through the combustion chamber and the free end 25a of which ends at one of the firebed-simulating means 12a- 12d, in a similar fashion as is illustrated in Fig. 2.

The reservoir 22 is constructed in such a way that it promotes or facilitates the supply of the pyrotechnical additive from the reservoir 22 in the direction of the metering opening 22b and the supply line 25. In particular, the metering means 20 are provided with displacement means displacement means 30, which are positioned inside the reservoir 22 for displacing the pyrotechnical additive contained in the reservoir 22 towards and through the at least one metering opening 22b.

As shown the two examples shown in Figure 4a (combined with its detail in Figure 4b) and Figure 4c the displacement means 30 comprise a rotatable driven screw conveyor 31 which is positioned at the bottom of the reservoir 22 and next to the at least one metering opening 22b. The displacement means 30 also comprise a motor means 32, in particular a servo-motor for rotating the screw conveyor 31 inside the reservoir 22.

During operation, the reservoir 22 is filled with pyrotechnical additive, that is poured into the reservoir 22 via the opening in the top of the reservoir, which opening is closed off by the closing lid 23, see Figure 3. In the embodiment shown in Figure 4c the screw conveyor 31 is completely submerged by the pyrotechnical additive and subsequent rotation of the screw conveyor 31 by means of the motor means 32 causes the pyrotechnical additive to be proactively displaced inside the reservoir 22 and near the bottom thereof towards the at least one metering opening 22b’-22b.

In the other example as shown in Figure 4a and in more detail in Figure 4b the reservoir 22 has an interior shaped as a funnel 33 directing the pyrotechnical additive towards an reservoir outlet 33’. The screw conveyor 31 is located near and in the reservoir outlet 33’. Upon rotation by means of the motor means 32 the screw conveyor 31 causes the pyrotechnical additive, which has been collected in the funnel 33 and the outlet 33’ to be proactively displaced from the reservoir outlet 33’ towards the at least one metering opening 22b’. The displaced pyrotechnical additive will exit the reservoir 22 via the at least one metering opening 22b’ and it will subsequently be received in the line 25 via a small pipe and the metering opening 22b.

In all embodiments shown in Figures 4a-4c, at the location where the pyrotechnical additive exits the metering opening 22b of the reservoir 22 the line 25 is connected to an air line 27 which is connected to a pump 26. By means of the pump 26, the amount of pyrotechnical additive held in the line 25 by means of a pressurized medium, for example air, can be blown in the direction of the outlet opening 25a.

When the pyrotechnical additive leaves the outlet opening 25a, which, as has already been mentioned, is positioned at the location of the firebed-simulating means 12a-12d, it will come into contact with the burning gas and thus create additional flame and fire effects, such as sparks.

To this end, the metering means 20 also comprise control means 28 (see Fig. 3) which pass control signals to the displacement means 30 or the pump 26, respectively, via suitable control lines 29a and 29b. More specifically, the control means 28 are configured in such a way that the control means are capable of actuating the motor means 32 and hence the screw conveyor 31 in terms of rotational speed and rotation time. By changing the rotational speed and rotation time of the screw conveyor 31 accordingly, the amount of the pyrotechnical additive exiting the reservoir 22 and entering the supply line 25 can be accurately controlled and thus the creation of additional flame and fire effects, such as sparks.

Irregular yet more realistic additional flame and fire effects can be created by actuating the motor means 32 and the air pump 26 sequentially. Sequentially means firstly that the displacement means 30 are actuated by the control means 28, resulting in the displacement of certain amount of pyrotechnical additive exiting the reservoir 22 and entering the supply line 25. Subsequently, the displacement means 30 are inactivated and the air pump 26 is actuated which blows this metered amount of pyrotechnical material through the supply line 25 in the direction of the outlet opening 25a by means of a short air pressure pulse via the air line 27 and the supply line 25. Upon leaving the outlet opening 25a on account of the air pulse delivered by the pump 26, the dispensed pyrotechnical additive will be brought to ignition at the location of the firebed-simulating means 12a-12d (see Fig. 1) by the burning gas and thus produce the additional flame and fire effects. The air pump 26 is in each case actuated briefly by the control means 28 for delivering an air pressure pulse in the air line 27 in the direction of the displacement means 30 and the supply line 25. To this end, the air pump 26 takes air from elsewhere and preferably from outside the combustion chamber 10 (see Fig. 1 and 3) via the inlet opening 27a. Thus, the air line 27 has such a length, as a result of which the air pump 26 and preferably the inlet opening 27a are arranged at some distance from and outside the combustion chamber 10. This prevents hot combustion flue gases from being introduced into the air line 27 via the inlet opening 27a, which could possibly cause the pyrotechnical additive metered into the supply line 25 to ignite spontaneously. The position of the inlet opening 27a of the air line 27 as far as outside the combustion chamber 10 is thus a safety aspect of the present gas hearth.

In this embodiment, a non-return valve has to be incorporated in the inlet line 27a which extends to the outside of the combustion chamber in order to prevent combustion flue gases from escaping from the combustion chamber 10 via the air line 27 and the inlet opening 27a instead of via the flue-gas discharge duct 11.

In a preferred embodiment, the inlet opening 27a of the air line 27 and the outlet opening 25a of the outlet line 25 are both in the combustion chamber 10. This results in a closed system, so that combustion flue gases cannot escape from the combustion chamber except via the flue-gas discharge duct 11. However, the inlet opening 27a has to be arranged in the combustion chamber 10 in such a way, for example at some distance from the firebed-simulating means, so as to prevent an undesired inflow of combustion flue gases.

In yet another embodiment, the air pump is not switched on or off by the control means 28, but the air pump is actuated continuously and an air stream is continuously blown in the direction of the supply line 25 and the outlet line 25a by the air line 27.

By means of suitable control signals which are emitted by the control means 28 to the displacement means 30 (motor means 32 and the screw conveyor 31) via the control line 29a, the rotational speed and time of the screw conveyor 31 can be controlled depending on a desired fire and flame display in the combustion chamber. The control means 28 can be programmed in advance with several fire/flame display settings, each setting being composed of a specific rotation speed/time schedule, which schedule provides a certain rotational speed/time behaviour of the screw conveyor 31 and thus a specific displacement/meter rate of pyrotechnical additive from the reservoir 22 towards the supply line 25.

Herewith the supply of the pyrotechnical additive via the outlet opening 25a to the burning firebed-simulating means 12a-12d can be made more random and unpredictable. The random unpredictable supply of pyrotechnical additive to the firebed- simulating means 12a-12d also contributes to a more realistic fire image, since this also produces random flame and fire effects, similar to the fire image of a conventional burning log fire.

The time period of the actuation of the screw conveyor 31 as well as its rotational speed may also be set randomly within a certain range, so that the amount of pyrotechnical additive during each metering from the reservoir 22 in the supply line 25 also varies. Consequently, the intensity of the resulting flame and fire effects vary with each dose. This also helps to create an improved simulation of the random and chaotic fire image of a conventional burning log fire.

The pyrotechnical additive preferably consists of granules, in particular a pulverulent or granular material. In particular, the pyrotechnical additive is a carbon- containing additive, in which the granules have a grain size of between 0.05 mm - 2.5 mm.

In a further embodiment, such as illustrated in Fig. 5a and 5b, wherein the metering means 20 are positioned under the firebed-simulating means 12a-12d of the gas hearth, as is illustrated in Fig. 1, the closure 23 is formed in such a manner that it forms part of the firebed-simulating means. In Fig. 5, the closure is denoted by reference numeral 230 and is formed as an imitation log. In this way, the metering means 20 can be fitted at a small distance below the level of the firebed-simulating means 12a-12d in the gas hearth, thus achieving a further reduction in the installation space.

It should be noted that although the sealing cap 230 is formed as an imitation log, it does not actively contribute to the play of flames and fire during operation. The sealing cap 230 will therefore not be porous and will also not be provided with a connection to the gas supply means 13, as illustrated in Fig. 1.