BE1019925A5 - DEVICE FOR DETECTING INPUT AIR FLOW IN DOMESTIC HEATING APPARATUS AND ASSOCIATED METHOD. - Google Patents

Abstract

The present invention relates to a device (1) for detecting the inflow rate of air in domestic heating appliances, said device (1) consisting of a flat support provided with at least one elongated element on which there is at least one resistance temperature detector or CTN, said device being mounted in a duct intended to bring air inside one of said appliances, said device being characterized in that it has said device being characterized in that it has said at least one elongated element inclined with respect to the main axis of said duct, and said at least one NTC oriented along the duct towards the outlet of the duct, that is to say in the opposite direction to that of the inlet of the air flow.

Description

Input air flow sensing device in domestic heaters and associated method

The present invention relates to a device for detecting the flow of inlet air in domestic heating appliances, able to read the speed of the air entering the stove and indirectly, the flow rate of the air sucked.

When setting up a biomass appliance for home heating, it is important to know the air flow rate and its inlet speed. These last data make it possible to systematically obtain an optimal combustion of wood or pellets, with significant advantages such as the reduction of waste, the reduction of emissions, a better yield, a greater cleanliness of the hearth, and others. The measurement of the air sucked up, it makes it possible to determine if the combustion is done efficiently, - if it is not the case, it is possible to intervene accordingly, by increasing or decreasing the speed of the extractor of smoke (thus modifying the flow of the sucked air), in order to bring the combustion back to its optimal values.

The device, which is based on the principle of the "thermal flowmeter", consists of two resistance temperature detectors of the CTN (negative temperature coefficient) type, that is to say resistors whose value is proportional to temperature, which are mounted on the same printed circuit but in different positions so as not to influence each other.

The first resistance temperature detector (hereinafter CTN) serves to measure only the temperature of the input fluid; the second CTN is controlled by means of an electric current of a known intensity, intended to bring it to a temperature higher than that of the fluid to be measured. The two NTCs are immersed in the fluid, their free surface directed towards the wall of the inlet tube of the air sucked by the apparatus, and the fluid cools the heated resistance, in proportion to its speed: as the flow increases, the dissipated heat increases and vice versa.

To detect the amount of heat dissipated during this cooling, the temperature change of the CTN is measured. The characteristics of the fluid (its pressure and temperature) have a considerable influence on the accuracy of such a measurement and a known solution (FIG. 10) to overcome this disadvantage requires the insertion of the CTN which measures the temperature of the inlet fluid ( temperature compensation) in the inlet tube, and to add to the firmware the possibility of choosing the operating height (pressure compensation), with regard to the pressure.

However, this solution has another disadvantage, related to soiling (dust, animal hair and others) that can be deposited on the resistance temperature sensors and affect the measurement.

Indeed, the device is placed parallel to the flow, with the temperature sensors (CTN) completely surrounded by the fluid (Figure 10). The dirt then remains stuck on the sensor, forming an insulating film. The heat detection by the device is therefore lower and the flow rate values, always determined by the device, are not always correct.

However, if the flow rate values are incorrect, the combustion adjustment can not be done correctly, and this causes undesired device malfunctions.

There is therefore a need for a solution that makes it possible to eliminate this serious drawback, by providing an input air flow detection device in biomass domestic heating appliances, which does not attract the stains on it and which reliably detects the flow of incoming air.

In addition, it is clearly necessary to find a solution that is economical and easy to manufacture, in order to introduce a product with a competitive price onto the market.

In particular, the object of the present invention is to provide a device for detecting the flow of input air into domestic heating appliances, which does not attract dirt on it and which reliably detects the flow rate of the appliance. inlet air.

The present invention also aims to provide a device that does not affect the air flow to be measured by blocking or reducing its introduction into the domestic heater.

Accordingly, the present invention relates to a device for detecting the flow of inlet air in domestic heating appliances, said device consisting of a flat support provided with at least one elongated element on which is located at minus a resistance temperature detector or CTN, said device being mounted in a duct intended to bring air inside one of said apparatus, said device being characterized in that it has said at least one elongated element inclined relative to the main axis of the duct, and said at least one NTC oriented along the duct towards the outlet of the latter, that is to say in the opposite direction to that of the inlet of the flow of air.

According to the invention, the device is mounted on a duct intended to bring air inside one of said appliances, said duct having an opening for mounting a cap provided with a unit of known type, said device being mounted on said opening of said conduit by means of an additional cap having at least one slot for the passage of said at least one elongated element, with a first inclined transverse wall, said cap being mounted on said opening in said conduit; .

In addition, according to the invention, said at least one slot has a second transverse wall inclined and parallel to said first transverse wall.

In addition, according to the invention, the device is mounted on a portion of conduit having at least one slot for the passage of said at least one elongate member, with a first inclined transverse wall, said conduit portion being engaged with any one led of known type.

The invention also relates to a method for detecting the input air flow rate in domestic heating appliances, comprising the use of a detection device consisting of a flat support provided with at least one elongated element on which there is at least one resistance temperature detector or CTN, said device being mounted in a duct for introducing air into one of said appliances, characterized in that said device is inclined with respect to the main axis of the duct, with said at least one NTC oriented along the duct towards the outlet of the latter, that is to say in the opposite direction to that of the inlet of the air flow.

We will now describe the present invention in an illustrative and non-limiting manner, according to one of its embodiments and in light of the accompanying figures. In particular: FIG. 1 shows a first embodiment of the device according to the invention, in a side view of a tube to which it is applied; FIG. 2 shows a first embodiment of the device according to the invention, in an exploded axonometric view; Figure 3 shows a first embodiment of the device according to the invention, in a view from below; Figure 4 shows a first embodiment of the device according to the invention, in an axonometric sectional view; FIG. 5 shows a first embodiment of the device according to the invention, in a front view of a tube to which it is applied; FIG. 6 shows a second embodiment of the device according to the invention, in a front view of a tube to which it is applied; Figure 7 shows a second embodiment of the device according to the invention, in a side view of a tube to which it is applied; FIG. 8 shows a second embodiment of the device according to the invention, in an exploded axonometric view; Figure 9 shows a second embodiment of the device according to the invention, in an axonometric sectional view, and Figure 10 shows a device according to the prior art, in an axonometric sectional view.

As can be seen from the figures, the flow sensing device according to the invention, designated in the figures by the numeral 1, pivots so that its main plane of development is perpendicular to the flow of air entering the apparatus, and is inclined with respect thereto to follow movement within the conduit 2.

If we now look at FIG. 10, the known ducts used to introduce the air into the heating apparatus, have an opening 3 on which is mounted a cap 4 provided with a slot 5, able to house the device 1.

If we now come to observe Figures 1, 2, 3, 4, and 5, the device 1 is mounted on a cap 6 having two slots 7 for allowing the passage of the arms or elongated elements 8 of the device 1. The slots 7 have inclined walls, so that the device 1, introduced into them, can adopt an inclined position, as shown in Figure 1.

Advantageously, the cap 6 can be mounted on any duct 2 of known type, such as those used to date in the heaters.

If we now observe Figures 6, 7, 8 and 9, the device 1 is mounted on a portion of duct 9 having a slot 7 intended to allow the passage of the device 1.

Advantageously, the duct portion 9 can be engaged with any duct 2 of known type which does not have the opening 3 described above.

The resistance temperature detectors 10, or CTN, are on the surface of the device 1 facing the wall of the duct 2, and towards the inside of the heater.

Advantageously, this prevents the stream from directly affecting the NTCs 10.

Thus, soils that are possibly carried together with the inlet air, never meet the NTCs 10 and, when they overheat, their orientation prevents most of the transported dirt from settling on them.

The solution described in the present invention limits the disadvantage of powder deposition on NTCs, by placing the device inclined in the flow direction, presenting the NTC protected by a printed circuit, in order to avoid accumulations of impurities on the NTC. their surface.

Advantageously, such a solution makes it possible to create a device for detecting the flow of inlet air into domestic heating appliances, which does not attract stains on it and which reliably detects heat.

Another advantage is the possibility of producing a device which does not affect the air flow to be measured by blocking or reducing its introduction into the domestic heater.

We have described the present invention in an illustrative and nonlimiting manner according to one of its preferred embodiments, but the skilled person may, of course, provide variations and / or modifications to the latter without departing from the part of its protection as defined in the appended claims.

Claims (5)

1. Device for detecting (1) the flow of inlet air in domestic heating appliances, said device (1) comprising at least one flat support, provided with at least one elongated element (8) on which is located at least one resistance temperature detector or CTN (10), said device (1) being mounted in a conduit (2) for introducing air into one of said apparatus, said device (1) being characterized in that it has said at least one elongated element (8) inclined with respect to the main axis of said duct (2) so as to follow the movement of the air flow inside said duct (2), and said at least one NTC (10) oriented along the conduit (2) to the outlet of the latter. 2. Device (1) according to claim 1, characterized in that it is installed in a duct (2) intended to bring air inside one of said ambient heating apparatus, said duct (2) having an opening (3) for installing a cap (4), said device (1) being mounted on said opening (3) of said conduit (2) by means of an additional cap (6) having at least one slot (7) for the passage of said at least one elongated element (8), with a first inclined transverse wall so as to cause said at least one elongated element (8) to adopt its inclined position, and in that said cap (6) is mounted in correspondence with said opening (3) provided in said conduit (2). 3. Device (1) according to claim 2, characterized in that said at least one slot (7) has a second transverse wall inclined and parallel to said first transverse wall. 4. Device (1) according to claim 1, characterized in that it is installed on a portion of conduit (9) having at least one slot (7) for the passage of said at least one elongated element (8), with a first transverse wall inclined so as to adopt said at least one elongate element (8) its inclined position, and in that said conduit portion (9) is engaged with any conduit (2) of known type. A method for detecting the flow rate of air entering an ambient heating apparatus, comprising the use of a detection device (1) comprising at least one support having at least one elongated element (8) on which is located at minus a resistance temperature detector or CTN (10), said device (1) being installed in a duct (2) intended to bring air into one of said apparatus, characterized in that said device ( 1) is inclined with respect to said duct (2) so as to follow the movement of the air flow inside said duct (2), with said at least one NTC (10) oriented along the duct (2) towards the output of the latter.