EP0990849B1 - Monitoring device for overheating of a hot water heater with a pierced diaphragm - Google Patents

Abstract

The water heater (1) has a cold water input pipe (2) connected to a cold water circuit (3) and a hot water output pipe (4) connected to a hot water circuit (5). The overheating controller (30) has an enclosure (31) divided by a deformable membrane (34) in a cold chamber (32) and in a hot chamber (33). The membrane (34) has a first face (37) and a second face (38) respectively turned towards the hot (33) and the cold (32) chambers. The cold chamber (32) is at a pressure of that in the cold water circuit (3) and the hot chamber (33) is at the pressure of the hot water circuit (5), so that the membrane (34) is displaced due to the pressure difference between the chambers (32,33). The controller (30) has means (45), for limiting the temperature rise of the water contained in the cold chamber (32), which is supported on the membrane (34). The temperature limiter (45) includes a passage (46) through the membrane (34) so that the cold water in the chamber (32) can flow towards the hot chamber (33). The passage (46) has two orifices ending in the faces (37,38) of the membrane (34) the transversal section of each orifice (47,48) is greater than the transversal section of the passage (46).

Description

The present invention relates to a device to control the overheating of a hot water generator.

Hot water generators usually encountered include a cold water inlet pipe connected to a cold water circuit and an outlet pipe hot water connected to a hot water circuit, a heat exchanger heat being interposed between the cold water circuit and the hot water circuit and a burner provides heat to the audit exchanger. Such a generator is known from FR-A-2 609 162.

After drawing hot water heated by the generator it is necessary to lower the temperature average water present in the heat exchanger. For this, the hot water generator is conventionally equipped a device for controlling the overheating of water present in the exchanger, this device comprising usually an enclosure divided by a membrane deformable into a cold room and a hot room, the deformable membrane having a first face and a second side respectively facing the cold room and towards the hot room, the cold room being subjected to the pressure in the cold water circuit and the chamber hot being subjected to the pressure prevailing in the circuit hot water, so the deformable membrane is displaceable under the pressure difference between the cold and hot rooms.

So the cold water stored in the room cold during the drawing is expelled by the membrane movable in the cold water circuit while the water present in the exchanger is transferred to the enclosure warm room. The hot water present in the exchanger is thus replaced by cold water.

However, the construction of such a water generator hot causes the installation of the device for controlling overheating in the vicinity of the hot water circuit. Through Therefore, during long draws of hot water, the cold water temperature in the cold room of the control device is strongly influenced to the point to get hot. The water thus reinjected into the exchanger heat when stopping the drawing is therefore less effective in combating overheating.

The object of the present invention is to remedy the disadvantages mentioned above by proposing a device for control which improves the action of the water injected into the exchanger when the water supply stops, and this by means of simple, effective and inexpensive means.

To this end, according to the invention, a device for control of the aforementioned type, is essentially characterized by what the control device includes means for limitation of the rise in temperature of the water contained in the cold room.

Consequently, the device according to the invention allows to return to the heat exchanger, when the drawing, water that is really cold compared to hot water temperature.

• les moyens de limitation de la montée en température de l'eau contenue dans la chambre froide sont portés par la membrane déformable ;
• les moyens de limitation de la montée en température de l'eau contenue dans la chambre froide comprennent au moins un passage qui traverse la membrane, de sorte que l'eau froide contenue dans la chambre froide s'écoule vers la chambre chaude, renouvelant ainsi l'eau contenue dans la chambre froide ;
• le passage possède deux orifices débouchant sur les première et deuxième faces de cette membrane, la surface de la section transversale des orifices étant supérieure à celle de la section transversale du passage ;
• la membrane déplaçable est sensiblement de forme en calotte sphérique, le passage traversant étant sensiblement radial et situé au sommet de la calotte sphérique ;
• le dispositif comprend en outre des moyens de rappel de la membrane pour diminuer le volume de la chambre froide et la deuxième face de la membrane comporte un élément d'appui des moyens de rappel, l'élément d'appui étant de même axe que le passage ; et
• la première face de la membrane est munie d'ergots en saillie vers la chambre froide.

The control device according to the present invention may optionally further include one or more of the following characteristics:

• the means for limiting the rise in temperature of the water contained in the cold room are carried by the deformable membrane;
• the means for limiting the rise in temperature of the water contained in the cold room comprise at least one passage which crosses the membrane, so that the cold water contained in the cold room flows towards the hot room, thus renewing the water in the cold room;
• the passage has two orifices opening onto the first and second faces of this membrane, the surface of the cross section of the orifices being greater than that of the cross section of the passage;
• the displaceable membrane is substantially in the form of a spherical cap, the through passage being substantially radial and situated at the top of the spherical cap;
• the device further comprises return means of the membrane to reduce the volume of the cold room and the second face of the membrane comprises a support element of the return means, the support element being of the same axis as the passage; and
• the first face of the membrane is provided with lugs projecting towards the cold room.

• la figure 1 est une vue en coupe longitudinale d'un générateur d'eau chaude en position arrêt incorporant le dispositif de contrôle de la surchauffe selon la présente invention ;
• la figure 2 est une vue analogue à celle de la figure 1, le générateur étant en position puisage ;
• la figure 3 est une vue en coupe transversale de la membrane déplaçable appartenant au dispositif de contrôle des figures 1 et 2 et sollicité par un ressort ; et
• la figure 4 est une vue agrandie de la partie A de la membrane déplaçable de la figure 3.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawings in which:

• Figure 1 is a longitudinal sectional view of a hot water generator in the off position incorporating the overheating control device according to the present invention;
• Figure 2 is a view similar to that of Figure 1, the generator being in the drawing position;
• Figure 3 is a cross-sectional view of the movable membrane belonging to the control device of Figures 1 and 2 and biased by a spring; and
• FIG. 4 is an enlarged view of part A of the displaceable membrane of FIG. 3.

The hot water generator 1 shown in the figures 1 and 2 comprises, in a manner known per se, a pipe cold water inlet 2 connected to a cold water circuit 3, a hot water outlet pipe 4 connected to a circuit hot water 5, a heat exchanger 6 interposed between the cold water circuit 3 and hot water circuit 5 and one fluid fuel burner 7 that transfers heat to the heat exchanger 6.

For example, the fluid fuel used here is natural gas which when a user draws water hot (Figure 2), burns forming a flame ramp 8 whose heat is transferred to the heat exchanger 6 placed above the burner 7 to heat the circulating water in this exchanger.

Natural gas is delivered to burner 7 according to the direction of arrows F via a power supply 10. The gas flow through the supply 10 is regulated by a valve 11 which is connected to a device 12 control of the gas inlet to the burner, to the passage of cold water in the cold water circuit 3.

The valve 11 consists of a valve head 13 integral with a valve stem 14 whose movement is linked to the servo device 12. The valve head 13 is biased by a spring 15 bearing against a seat of valve 16 formed in the gas inlet pipe 10. The servo device 12, known per se, is consisting of a reservoir 20 disposed in the input circuit cold water 3 downstream of which is disposed, relative to the flow direction F1 of cold water, a venturi 21. A mobile element 22, placed in the tank 20, moves in depending on the pressure difference between its two sides. The value of the pressure difference is caused by the venturi and is related to the flow of cold water in the cold water inlet circuit 3. On the element displaceable 22 is mounted the rod 14 of the valve 11.

When the hot water generator is in position stop (Figure 1), no pressure drop is caused via the venturi 21 inside the water inlet circuit cold 3. The movable element 22 is therefore inactive and the head 13 of the valve 11 rests on its seat 16. The power supply 10 in gas is therefore completely obstructed. Burner 7 is off.

When the operator draws hot water (Figure 2), the venturi 21 creates a pressure drop in the cold water circuit 3, which induces a displacement towards the top of the movable element 22, driving the rod 14 of the valve 11. The head 13 of the valve is detached from its seat 16, causing the gas to pass through the supply 10, to the burner 7.

When stopping the drawing, it is necessary not to not cause the heat exchanger to overheat 6. This overheating is caused by the generation of heat component parts of the hot water generator neighbors of the heat exchanger which were themselves heated during the drawing. For this it is necessary replace the hot water present in the exchanger with a amount of cold water.

For this, the hot water generator is provided with in addition to a device 30 for controlling the overheating of hot water. This control device includes a enclosure 31 divided into a cold room 32 and a hot chamber 33 by a deformable membrane 34.

The cold room 32 is connected to the pipe cold water inlet 2 through a pipe 35 while the hot chamber 33 is connected to the hot water outlet 4 by tubing 36. Thus, the cold room is subjected to the pressure in the cold water inlet pipe 2 and the hot chamber 33 is subjected to the pressure prevailing in the hot water outlet pipe 5. The deformable membrane 34 is therefore movable under the difference of pressure between the cold and hot rooms.

The membrane 34 is resiliently recalled in direction of the cold room 32 by a spring of compression 40 which is interposed between the bottom of the chamber hot 33 and the second face 38 of this membrane.

Furthermore, as shown more particularly FIG. 3, the membrane 34 is substantially shaped in spherical cap so as to match the walls of cold rooms 32 and 33 which are themselves convex. Of more appropriately, the membrane 34 is shaped approximately cylindrical with axis X-X, the bottom of which is curved and whose height is low compared to the bottom. The membrane 34 is made of a deformation material elastic and has a small thickness by relative to the diameter of the spherical cap. The S summit of the spherical cap is thicker so to constitute a support stop 51 projecting from the second face 38. The compression spring 40 is in stop on the second face 38 of the membrane by via a ring-shaped plate 52 itself fitted on the support stop 51 and on the second face 38.

When the generator is in the off position (Figure 1) the deformable membrane 34 is stressed by the compression spring 40 towards the cold room 32 so that the volume of this chamber is very small. In the drawing position (figure 2), the pressure difference prevailing between the cold water circuit 3 and the water circuit hot 5 (caused by venturi 21 and loss of charge of water in the circuit) causes the displacement of the membrane 34 against the compression spring 40 in direction of hot room 33. This room has then a minimum volume and the cold room 32 is filled of cold water. When the hot water withdrawal stops, the membrane 34 expels cold water from the chamber cold 32. This water is then transferred to the exchanger heat 6, which allows it to avoid overheating this exchanger.

The control device 30 is located in the vicinity of the hot water circuit 5, which causes when drawing hot water, warming the cold water contained in cold room 32 (Figure 2). To avoid the rise in temperature of this water, the control device 30 has means 45 for limiting the rise in temperature of the water in the cold room 32 (Figures 3 and 4).

The limiting means 45 are carried by the deformable membrane 34 and consist of a passage 46 which radially passes through this membrane. In this example, the passage 46 is on the X-X axis.

The passage 46 leads to the first face 37 by an orifice 47 and on the second face 38 by an orifice 48. These orifices are, in cross section, of good surface greater than that of passage 46.

As shown more particularly in Figure 3, the first face 37 of the membrane 34 is further provided lugs 50 regularly distributed and which project in direction of the cold room 32. These pins prevent a too strong adhesion of the membrane 34 to the bottom of the chamber cold 32 and facilitates the detachment of this membrane during hot water.

The passage 46 allows, in the water withdrawal position hot, a flow of cold water contained in the cold room 32 to hot room 33. This flow is favored by the pressure in the cold room 32 which is higher than the pressure prevailing in the chamber hot 33. This flow causes the renewal of cold water in cold room 32 and prevents the rise in temperature of this water.

It is understood that the dimension of passage 46 does not affect almost no difference in pressure between the cold room 32 and hot room 33.

Furthermore, the means 45 for limiting the rise in cold water can take any other than a passage 46, such as a conduit located outside enclosure 30 and which communicates cold rooms 32 and hot rooms 33.

Claims (7)

1. A device for controlling overheating in a boiler (1), the boiler (1) comprising an inlet pipe (2) for cold water connected to a cold-water circuit (3) and an outlet pipe (4) for hot water connected to a hot-water circuit (5),
   the device (30) for controlling overheating comprising an enclosure (31) divided by means of a deformable membrane (34) into a cold chamber (32) and a hot chamber (33), the deformable membrane (34) having a first face (37) and a second face (38) respectively facing the cold chamber (32) and the hot chamber (33), the cold chamber (32) being subjected to the pressure prevailing in the cold-water circuit (3) and the hot chamber (33) being subjected to the pressure prevailing in the hot-water circuit (5) so that the deformable membrane (34) is displaceable under the effect of the pressure differential existing between the cold (32) and hot (33) chambers,
   characterised in that the control device (30) has means (45) for limiting the rise in temperature of the water contained in the cold chamber (32).
2. A control device as claimed in claim 1, characterised in that the means (45) for limiting the rise in temperature of the water contained in the cold chamber (32) are borne by the deformable membrane (34).
3. A control device as claimed in claim 2, characterised in that the means (45) for limiting the rise in temperature of the water contained in the cold chamber (32) comprise at least one passage (46) running through the membrane (34) so that the cold water contained in the cold chamber (32) flows to the hot chamber (33), as a result of which the water contained in the cold chamber (32) is replenished.
4. A control device as claimed in claim 3, characterised in that the passage (46) has two orifices (47, 48) opening at the first (37) and second (38) faces of this membrane (34), the surface area of the orifices (47, 48) in cross section being larger than that of the cross section of the passage (46).
5. A control device as claimed in claim 3 or 4, characterised in that the displaceable membrane (34) is of a substantially spherical dome shape, the passage (46) running therethrough being substantially radial and located at the apex (S) of the spherical dome.
6. A control device as claimed in claim 5, characterised in that it also has return means (40) for the membrane (34) in order to reduce the volume of the cold chamber (32) and the second face (38) of the membrane (34) has a bearing member (51) for the return means (40), the bearing member (51) having the same axis as the passage (46).
7. A control device as claimed in claim 5 or 6, characterised in that the fist face (37) of the membrane (34) is provided with lugs (50) projecting towards the cold chamber (32).

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