FOG-GENERATING SYSTEM EQUIPPED WITH SAFETY AND REGULATING DEVICES OF THE FLOW-RATE OF ITS FOG-GENERATING FLUID

Abstract

A fog-generating system (1) is described, comprising: a tank (5) containing fog-generating fluid; a pump (3) connected to the tank (5) to withdraw the fog-generating fluid therefrom; a serpentine (2) connected to the pump (3) to receive the fog-generating fluid pumped by the pump (3), the serpentine (2) being divided into a first section (A) connected to the pump (3) and a second section (B) connected to the first section (A) and designed to emit dry fog (7) as output; a battery (6) connected to the serpentine (2) to pass electric current inside the serpentine (2) and to supply the pump (3); a differential amplifier (11) connected to the second section (B); and a threshold comparator (13) which, upon exceeding a certain voltage, a stop index of the serpentine (2) in the second section (B), breaks the supply to the pump (3).

Claims

1. A fog-generating system (1) comprising: at least one tank (5) containing fog-generating fluid; at least one pump (3) connected to said at least one tank (5) and designed to withdraw said fog generating fluid therefrom; at least one serpentine (2) connected to said at least one pump (3) and designed to receive said fog-generating fluid pumped by said pump (3), said serpentine (2) being divided into a first section (A) connected to said pump (3) and a second section (B) connected to said first section (A) and designed to emit dry fog (7) as output; and at least one battery (6) operatively connected to said at least one serpentine (2) and designed to pass electric current inside said serpentine (2) and to supply said pump (3), wherein a supply of said pump (3) is taken from a resistive divider obtained from said second section (B) of the serpentine (2), and, till the serpentine (2) remains dry, it is uniformly heated and its resistance proportionally increases, while, when the fog-generating fluid gets in contact with said first section (A), its heating and the following status change prevent the first section (A) from being overheated, limiting its resistance increase, and the second section (B), instead, is affected only by its vapour phase, and will be heated more, increasing the voltage at its terminals, so that the pump (3) has a supply voltage as higher as the second section (B) is more “dry”, and consequently increases the flow-rate till a balance point is found between temperature distribution and flow-rate.

2. The fog-generating system (1) according to claim 1, further comprising: at least one differential amplifier (11) operatively connected to said second section (B), said differential amplifier (11) taking a control signal from said serpentine (2) and adapting it, through amplification or reduction, to a supply of said pump (3); and at least one threshold comparator (13) operatively connected to said differential amplifier (11) and to said pump (3), said threshold comparator (13), upon exceeding a certain voltage, which is a stop index of said serpentine (2) in the second section B), being designed to break the supply to the pump (3).

3. The fog-generating system (1) according to claim 1, wherein said serpentine (2) is immersed in an inert material and inside a refractory container, which insulates it from atmospheric oxygen, with a flame retardant function.

4. The fog-generating system (1) according to claim 1, wherein said serpentine (2) is made of conductive material.

5. The fog-generating system (1) according to claim 1, wherein said divider obtained from said second section (B) is made of austenitic stainless steel, or of any metallic material with a sufficiently high melting point.

Description

[0018] The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which:

[0019] FIG. 1 is a schematic view of a first preferred embodiment of the fog-generating system according to the present invention;

[0020] FIG. 2 is a graph which shows the operation of the fog-generating system according to the present invention; and

[0021] FIG. 3 is a schematic view of a second preferred embodiment of the fog-generating system according to the present invention.

[0022] With reference to the Figures, preferred embodiments of the present invention are shown and described. It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) can be made to what is described, without departing from the scope of the invention as contained in the enclosed claims.

[0023] With reference to FIG. 1, the fog-generating system 1 of the present invention, in its simpler form, substantially comprises at least one serpentine 2 made of conducting (resistive) material, in which electric current from at least one battery 6 is made pass.

[0024] Contrary to other devices in which the current is controlled in order to keep the temperature of the serpentine 2 constant or at least within safety limits through external thermometers, namely a volt-ampere metrical measure of the resistance of the serpentine itself (index of its temperature), but above all through software- or firmware-based digital systems (which unavoidably imply a risk of computer error), the system can be wholly passive or, at most, controlled by basic electronics without computers.

[0025] As shown in FIG. 1, a fog-generating fluid (not shown) is pushed into the serpentine 2 through at least one pump 3, which withdraws it from at least one tank 5 which contains the fog-generating fluid.

[0026] The supply of the pump 3 is taken from a resistive divider obtained from a second section B of the serpentine 2—typically made of austenitic stainless steel, but which can be made of any metallic material with a sufficiently high melting point.

[0027] Upon supplying the serpentine 2 through the contactor of the battery 6—obviously an example, which can be replaced by SSR systems, MOSFETs, etc.—the pump 3 is directly supplied.

[0028] Till the serpentine 2 remains dry—and this occurs till the pump 3 is triggered and increases its pressures (approximately in one or two seconds), the serpentine 2 is uniformly heated and, with the same law, its resistance proportionally increases.

[0029] When the fog-generating fluid gets in contact with a first section A, its heating and the following status change prevent the first section A from being overheated, limiting its resistance increase.

[0030] The second section B, instead, is affected only by the vapour phase, which nominally removes a lower amount of heat, and it is be heated more, making the voltage increase at its terminals.

[0031] Since the power absorbed by the pump 3 is negligible with respect to the power of the serpentine 2, the pump 3 will have a supply voltage as high as much the second section B (over-heater) is “dry”, and consequently increases the flow-rate till a balance point is found between temperature distribution and flow-rate.

[0032] With a suitable balancing the system 1 will find the operating point that allows it to emit dry fog 7, self-regulating itself independently from the external temperature, from the fluid temperature and partly from the charge status of the battery 6.

[0033] With reference to the previous diagram of FIG. 1 and to the graph of FIG. 2, the self-regulation principle has been described: it is now necessary to examine, for more completeness and operating safety, what can happen in the extreme cases for safety, and the suitable methods for safety keeping.

[0034] As first operating case, should the fog-generating liquid run out, in addition to the end of the delivery, an excessive overheating of the serpentine 2 could occur due to lack of cooling.

[0035] In this case, the temperature could increase till it causes the melting of a section of the serpentine 2, which, being protected by a fireproof sheath, would not cause other dangers, while the machine would stop.

[0036] As second operating case, the serpentine 2 could fail due to construction defects, typically in the second section B which is the hotter one.

[0037] In this case, the pump 3 would be supplied at the maximum power, delivering the fluid in the interruption.

[0038] Being the fluid inflammable, if taken to its ignition temperature, this could cause a fire principle.

[0039] In order to solve this, the fog-generating system 1 of the present invention can therefore be equipped with a passive protection.

[0040] For such purpose, the serpentine 2 is inserted in an inert material and inside an enough refractory container, which insulates it from the atmospheric oxygen.

[0041] Since the contact with the oxidising material is now lost, the flame cannot be triggered, nor be propagated.

[0042] Upon interrupting the serpentine 2, the triggering is also lost, preventing new switch-on operations.

[0043] If the serpentine 2 is interrupted in the first section A, everything stops, if it is interrupted in the second section B, the pump 3 goes on entering fluid, which soaks the inert material, cooling it.

[0044] As alternative, the fog-generating system 1 of the present invention can be equipped with an active protection, as can be better seen in FIG. 3.

[0045] For such purpose, with the introduction of two components made of discrete electronics, described below, the last possible inconveniences are solved. The first component stage is at least one differential amplifier 11 operatively connected to the second section B of the serpentine 2, which, by taking the control signal from the serpentine 2, adapts it (amplifying or reducing it) to the correct supply of the pump 3.

[0046] The second component stage is at least one threshold comparator 13 operatively connected to the differential amplifier 11 and to the pump 3, which, upon exceeding a certain voltage (index of the interruption of the serpentine 2 in the second section B), breaks the supply to the pump 3.

[0047] In this way, any risk of turning-on is removed and the feedback control is improved, without introducing digital elements controlled by computer resources subjected to hidden software errors.