Steam generator.

The invention relates to a steam generator which is used in a humidifier for an air conditioning system and, more particularly, to an aircraft air conditioning system.

Humidifiers for aircraft air conditioning systems are known and reference may be made, for example, in the patent application No. 89 02063.

In this application, there is described a humidifier for air conditioning system which comprises a hot air circulation duct to moisten, a steam generator whose output is located on top of a divergent cone s' extending to the inner wall of the sheath, the lateral surface of the cone being provided with holes for passing the hot air and to mix homogeneously, to the steam generated by the steam generator.

the advantages provided by the known use of a steam generator in a humidifier may be mentioned and, among them, being able to use water containing minerals and, in particular, the circuit water plane. There is also the fact that it works without qu'apparaîsse condensation in the duct leading the air to the aircraft cabin.

An object of the invention to provide a steam generator used in such a humidifier which the amount of steam output is fully controllable, in particular, depending on the need of moisture in the air.

For this purpose, a steam generator for a humidifier of an air conditioning system connected, via a pipe, at a dilution cone placed inside an air circulation casing of the humidifier comprises a container provided with a steam outlet generated within said container, said port being connected to said conduit from the humidifier, a water filling orifice connected to the output of a feed valve whose input is connected to a source of water supply, and, inside said container, at least two electrodes partially plunged into the water to a certain level, in the container, said electrodes being supplied at constant voltage, and a control unit which measures the intensity of current through said electrodes and maintains the value of the intensity of this current within a range of current frame a set value by controlling the opening of the water supply valve when the amount of current passing through said electrodes has a value falling below the fork and which controls the closure of the feed valve when the intensity of the current increased to a value amount above the range.

The powered electrodes partially immersed in the water contained in the vessel, the electric current flows in the water and the amount of heat generated depends on the depth of water in which the electrodes are immersed. The amount of steam they generate and thus exits the vessel is directly related to the amount of current therethrough and, by varying the amount of water in the container and therefore the water level is varied the current and thus the amount of steam generated. The control unit therefore uses this fact to maintain the current in a power range and maintain, through this, the humidity in the cockpit, or any other part of the plane constant.

According to another characteristic of the invention, said reference current is generated by the control unit from the difference between the value of the signal delivered by an hygrometer with a humidity setpoint.

The amount of steam generated is perfectly regulated on the humidity in the cockpit of the aircraft, or any other party, according to a preset setpoint.

According to another characteristic of the invention, the container is further provided with an emptying orifice connected to the inlet of an electrically operated drain valve, the inlet of said control valve being connected to the 'control unit for performing, at times determined by the control unit itself, the evacuation of a certain quantity of water contained in the container with simultaneous interruption of the current in the electrodes, this operation being immediately followed by opening the supply valve command to return the current in the electrical means on the inside of the fork.

When the water evaporates, not only the level in the lower container, but the concentration of minerals increases. This has the effect, for a given electrode current, reduce the depth of the water in which the electrodes are immersed. After a certain operating time, this depth is insufficient. By removing a certain amount of water and filling with drinking water available in the aircraft, it decreases the concentration in mineral elements, which increases the resistance thereof, until a level of operation. The current electrode is switched off to avoid, during discharge of leakage current by the water downstream of the drain valve.

According to another characteristic of the invention, the container is removably mounted on a support which carries, in addition, the control unit and the supply and drain valves, the control unit also controlling, of one hand, the supply valve for filling the container when the latter has just been installed on the support or has just been turned on and, on the other hand, the drain valve to empty the container at each stop and the generator at the time of change.

Thus, a humidifier equipped with a steam generator having this characteristic is particularly safe since no water, or at least little water remains inside the container.

According to another characteristic of the invention, the container drain port is at a level which is above the bottom of the container.

When the container is emptied, there remains a reserve of water which, once mixed with water introduced via the filling valve, allows, at the time of restarting, to have a medium containing sufficient minerals, therefore a medium sufficiently conductive so that the generator can function. A shutdown of the generator, the emptying of the container is controlled, but there remains some mineralized water in the reserve, allowing a subsequent restart.

According to another characteristic of the invention, the discharge orifice and the filling orifice of the container are at the base of the container, combined and are represented by a single tube projecting from either side of the container bottom , the outlet of the filling valve being connected to said tube via a bent tube to have a linear portion substantially parallel to the longitudinal axis of the container.

According to this embodiment of the invention, this is the part of the tube projecting from the bottom and inside the container which forms the background and les'parois side of the tube container, the water supply for reboots.

According to one characteristic of the invention, the regulating unit consists of a control unit with microprocessor.

Thus, the steam generator of the invention has operating characteristics that can be easily modified by changing operating parameters in the program of the microprocessor.

According to another characteristic of the invention, the container comprises a level detection electrode the lower edge is in level above the normal maximum level of the water contained in the container and which is connected to the control unit which, when it detects a current in this electrode, controls the interrupting current through the electrodes and the emptying valve for emptying the container.

Thus, in case of malfunction of the generator, the water level in the container is abnormally high, there is in this current detection electrode and the control unit controls its judgment.

According to another characteristic of the invention, the steam generator is provided with a movable support in translation along the main axis of the vessel and supporting a tubular part connected to the humidifier tube and which is connected removably on the steam outlet orifice of the container, and pads of connections receiving container of the connection pads to which are connected the electrodes of the container.

Thus, away from the container, the support pads disconnects the container and disconnects the container opening, it can be removed.

According to another characteristic of the invention, the container is provided with an electrode connected to the regulating unit, and which is connected inside the vessel to a first terminal of a fuse the other terminal is connected to one of main electrodes, the regulating unit verifying, at the time of installation of a new vessel, whether the fuse is conducting or not, the control unit, in the first case, sending into the fuse a current intense enough to melt it, and in the second case, prohibiting starting the generator.

This makes it impossible to mount a vessel that has already been used.

According to another characteristic of the invention, the control unit receives the temperature sensor signal and a humidity probe mounted in the air circulation casing of the humidifier and, when these exceed predetermined values ​​it commands the cutting of the electrode current and the opening of the drain valve.

According to another characteristic of the invention, the control unit receives the temperature sensor signals placed close to the container and, when these signals exceed a predetermined value, it commands the cutting of the electrode current and the opening the drain valve.

These means are security measures that stop the generator when a malfunction is detected.

The characteristics of the invention mentioned above, as well as others, will emerge more clearly on reading the following description of an exemplary embodiment, said description being given in relation with the accompanying drawings, in which:<ul><li>Fig. 1 shows the block diagram of a humidifier using a steam generator according to the invention,</li><li>Fig. 2 shows a sectional view of a steam generator according to the invention, said generator being ready for operation, and</li><li>Fig. 3 is a steam generator of a sectional view according to the invention, the container of the generator being shown inclined and ready to be removed.</li></ul>

Fig. 1 shows an air flow duct 1 of an aircraft, said air being previously heated to be humidified. In the cylindrical duct 1 is installed in the axis of the sheath, the mouth of outlet 2 of a steam generator 3, the fastening means of the mouth 2 not being shown. The outlet opening 2 is connected to the steam generator 3 via a pipe 4 which passes through the wall of the sheath 1.

The steam generator 3 receives via a water pipe 5 of the source (not shown) of the aircraft, while through line 6, is connected to an overflow (not shown). It is connected by a line multiwire 7, to a power supply (not shown). It is also connected, via a wire 8, to a humidity sensor 9 mounted, for example, in the cockpit of the aircraft, by son 10, 11, respectively at a temperature detector 12 and a detector humidity 13.

Release from the mouth of around 2, is mounted the small base of a cone 14 the same axis as the longitudinal axis of the sheath 1 and whose large base is secured to the inner surface of the sheath 1, downstream of mouth 2. the side wall of the cone 14 is perforated with holes through which passes the hot air thus enters the cone 14 (arrow A), the flow regime of the air downstream of the cone 14 being so turbulent to ensure a homogeneous mixture of air and water vapor emitted from the mouth 2..

The steam generator 3 shown in detail in Fig. 2 comprises a support 20 on which is mounted a container 21 of essentially cylindrical shape with both bases are frustoconical.

The top and bottom ends of the container 21, the latter respectively has openings 22, 23 bounded by axial tubes 24, 25. The end inside the container 21 of the tube 25 is at a level higher than the bottom 26 of the container. Indeed, the lower tube 25 is projecting from either side of the bottom of the container 21. The upper tube 24 is projected only outwardly of the container 21. On its upper wall 27, the container 21 is provided with three studs 28, 29, 30 equidistant which are respectively connected, inside the container 21, three metal electrodes 31, 32, 33. these are parallel to the longitudinal axis of the vessel and are immersed up to a certain depth in the water contained therein to a certain level in the container. Fig. 2, in thin dashed lines, inside the container 21, represents the water contained in the container 21. A fourth terminal 34 also provided on the upper wall 27 is connected to a fourth metal electrode 35 parallel to the axis longitudinally of the container 21 and whose lower edge is at a level above the lower edges of the main electrodes 31, 32, 33. a fifth block 37 is provided on the upper wall 27 of the container 21 and is connected, inside the -ci, to a first terminal of a fuse the other terminal 38 is connected to one of electrodes 31.

The lower tube 25 is fitted to a first end of a tube 39 which laterally receives a conduit 40, the other end of tube 39 being connected to the inlet of a drain valve 41 electrically controlled. The output of the valve 41 is connected to the pipe 6 already shown in Fig. 1. It is mounted integral with the support 20. The duct 40 has an elbow 42 and a linear portion 43 substantially parallel to the longitudinal axis of the container 21. At the end of the linear portion 43, is provided a flare 44 opposite the end 45 of a second pipe comprising an elbow 46 and a connecting portion 47 at the outlet of a filling valve 48 electrically controlled. The valve 48 has its input connected to the pipe 5 already shown in FIG. 1. The free end 45 of the second pipe 46, 47 is advantageously provided with a small hole so that water which escapes drip-drop falls in the flaring 43 of the first pipe 40. This arrangement is provided for electrically insulating the water contained in the container 21 of the electrical ground of the valve 48.

The upper tube 24 of the container 21 is fitted over a tubular portion 49 of a support 50. The latter is constituted by a plate 51 integral with the tubular portion 49 and on which there are provided five female pads 52-56 which are respectively fit on the stud 37, the three male terminals 28, 29, 30, and the male terminal 34 of the container 21. the tubular portion 49 is intended to slide axially in a bush 57 integral with the support 20. on one of its generatrices, the tubular portion 49 is provided with a rack 58 meshing with a toothed wheel 59 whose axis is rotatably mounted on the support 20. the tubular portion 49 receives in its upper part, the pipe 4 already shown in Fig. 1 and which connects the steam generator 3 to the humidifier.

On the support 20, is also mounted a control unit 60 having three outputs 61, 62, 63 respectively connected to the three female terminals 53, 54, 55 (themselves connected to the electrodes 31, 32, 33), an input / output 64 connected to the pad 52, an input 65 to which is connected the fourth terminal 56, two outputs 66, 67 respectively connected to the control inputs of the valves 48, 41, an inlet 68 connected to a temperature sensor 69 mounted on the support 20 a multiwire inlet 70 receiving, via the multiwire line 7 already shown in Fig. 1, the supply voltages required for the operation of the generator, and three inputs 71, 72, 73 respectively connected to the lines 8, 10, 11 already shown in Fig. 1. Remember that these lines 8, 10, 11 are respectively connected to a hygrometer 9 advantageously mounted in the cockpit of the plane, a temperature sensor 12 and a humidity sensor 13 both mounted in the duct 1.

When turning the toothed wheel 59, the latter leads upwardly through the rack 58, the support 50. The female terminals 52-56 from separating male studs 28, 29, 30, 34, 37 of container 21 and its tubular portion 49 disengages from the upper tube 24 of the container 21. As shown in Fig. 3, the tubular part 39 is pivotable through a certain angle about an axis perpendicular to the support plane 20 and result, in this movement, the container 21. The latter can then extract liter if it disconnects its lower tube 25 of the tubular portion 39.

Note that in Fig. 3, the connections of the pads 52-56 to the control unit 60 are not shown in order not to overburden the drawing.

The control unit 60 is advantageously controlled by a microprocessor, so that the operation of the steam generator of the invention is linked to the microprocessor of the control programs.

Thus, the control unit 60 receives signals from the two temperature sensors 12, 69, a humidity sensor 13 and a hygrometer 9 and control, based on the received signals and their processing by the microprocessor, the electrodes 31, 32, 33 and valves 41, 48.

The operating principle is as follows: the three electrodes 31, 32, 33 are supplied with three-phase alternating voltage of substantially constant value and immersed, to a certain depth in the water contained in the container 21. This n is partially filled with water. The value of the current flowing in the electrodes 31, 32, 33 is proportional to the depth of water which wets and the conductivity of the water in the container. It increases with the concentration of minerals. The water in the container is heated by the Joule effect and the amount of water that evaporates is directly proportional to the value of the current flowing in the electrodes 31, 32, 33. The generated steam is extracted from the vessel via line 4 and joins the smaller base of the cone 14 in the sheath 1 to mix with the air flowing therethrough and dampen.

By evaporating the water level in the container 21 lowers and the electrodes 31, 32, 33 are immersed to a lesser depth, which has the effect of reducing the intensity of the current flowing between them. In fact, the decrease of the water level is accompanied by an increase in the concentration of water in minerals. The level of decline is however leading to increased concentration and the electrodes 31, 32, 33 are then the seat of a lesser amount of steam.

When the control unit 60 detects a decrease in the intensity of the current electrodes of a certain amount relative to a given reference current (quantity, for example, of the order of 10%), it controls the opening of the valve 48. the end 45 of the pipe 46 provides, drop by drop, water in line 40, which adds, by the principle of communicating vessels (the upper end of the flare 44 being higher than the water level in the vessel), the water in the container 21. the water level therein increases and the intensity of the electrode current increases proportionally. When it has reached an intensity greater than a certain amount (e.g. 10%) relative to the current setpoint, the control unit 60 controls the closure of the valve 48. The intensity of the current flowing in the electrodes 31, 32, 33 remains within a current range centered on the value of the reference current. The amount of generated steam, and, by consequence, the humidity in the cockpit, thus remain substantially constant, the effect of hysteresis introduced by the close operation of the regulating unit 60.

The control unit therefore performs cycles during which water is introduced into the vessel to adjust the current drops obtained during the evaporation. At certain times, which may be predetermined or otherwise determined by the control unit depending on the history of the variation of electrode current, the unit 60 controls the opening of the valve 41 for discharging a certain amount of water which itself also is either predetermined or determined by the control unit itself according to this history. The opening of the valve 41 is performed simultaneously with the breaking of the current to the electrodes, in order to prevent current leakage by water drain downstream of the valve 41. When the valve 41 closed, it commands the opening of the valve 48 for the introduction of water into the container. In this way, the increase in the concentration of minerals during the evaporation is compensated, not all cycles, which is not necessary, but at times.

In the control unit 60, the value of the signal provided by the hygrometer 9 is compared with a reference value of the moisture content and the result of this comparison is to establish, in the control unit 60 it -even to the reference current in the electrodes. This is, as we have seen, from the current setpoint value that the control unit 60 maintains the current between electrodes in a certain range of current. If the humidity in the cockpit is lower than the humidity set point, the control unit 60 increases the reference current in proportion to the difference between these rates. Similarly, if the rate is higher than the humidity set point, the control unit 60 establishes an electrode current setpoint decreased in proportion to the difference in rates.

temperature sensors, one near the container, the other in the sheath, may have, according to a simplified operation of the invention (related to operation programs of the microprocessor unit 60), a security role. If the temperature is too high or if it varies too suddenly, the current in the electrodes is interrupted.

If the water level in the container is too high, as this pourait result from a malfunction of a valve, a current can flow between the electrode and one of the electrodes. It is the control unit detects this current and which then controls the opening of the drain valve and system shutdown.

As we have already mentioned, the tubular portion protrudes from both sides of the container bottom. The role of the projecting portion inside the container, is able to constitute a reserve of water containing minerals. Thus, by installing a new container, you can fill the drinking water supply of the aircraft and send the current in the three electrodes which can then begin to work normally.

When installing a new container, the control unit checks the driver status of the fuse by injecting, for example, by the stud, a current. If the fuse is conductive, the control unit sends, in the fuse, a sufficiently high current to melt then initializes a timer and, after a time which is defined as the lifetime of the container triggers an alarm (not shown). By cons, if it is not conductive, this means that one has installed a container which has already been used and the control unit signals the, for example, by an LED installed in the cabin. This function aims to limit clogging of the electrodes 31, 32, 33.