EP1098138A1 - Device for controlling a generator of hot fluid in liquid or gaseous form - Google Patents

Abstract

The regulator for a hot fluid generator, e.g. for producing steam for a smoothing iron, has a chamber for the incoming cold fluid equipped with a level detector in the form of a float (15) connected by a supple tube (20) to a connector (24) passing through the chamber's cover. It incorporates an angular interrupter switch, e.g. a mercury switch (M) in the immediate vicinity of the float, with its electrical conductor emerging from the chamber through the supple tube. The regulator also has an electronic controller which starts and stops a pump delivering the cold fluid.

Description

The present invention relates to hot fluid generators, under liquid or gaseous form and more particularly to a device for regulating these generators.

Typically these are hot water or steam generators, but the invention also applies to generators of other liquids or gases hot.

To guarantee the proper functioning of such a generator, it is necessary limit the impact of the introduction of cold liquid into the generator tank as the hot liquid or the vapor of this liquid is used. It is necessary therefore be able to frequently introduce small doses of cold liquid.

Likewise to guarantee consistency of the stored pressure energy in the generator tank, you must be able to maintain the constant distribution of the volumes of liquid and gas in said tank.

To achieve these goals it is necessary to be able to measure or detect the level of liquid in the generator tank with great precision to regulate the addition of liquid and thermal power in a sufficiently fine manner. This is not the case in existing generators and one of the main aims of the invention is to provide a method and a device for fine and precise regulation of the liquid level in the generator tank.

In addition, existing generators are generally regulated in pressure, i.e. the supply of the tank heating element (s) are controlled by a pressure sensor. The thermal inertia of these tanks is not negligible, so that after reaching the desired pressure in the tank and therefore cut off the power to the heaters the temperature of the liquid in the tank continues to increase and therefore the pressure too, causing uncontrolled overshoot of the set pressure in the tank. Another object of the present invention is to provide a new method and a regulating device avoiding as much as possible these pressure overruns set point in the generator tank.

These generators of liquid or hot gases are intended to be versatile and able to supply several utensils with water vapor in particular or different accessories. It is obvious that the electrical power assigned to the heating of the liquid varies according to the envisaged application, it is lower for the use of an iron only to power a cleaning accessory to the steam. Generally to avoid overconsumption, these generators are equipped with a switch allowing manual adjustment of the power of heating at two preset levels. However, this is often not satisfactory because the user forgets to switch the power to the heater when it change accessory. Yet another object of the present invention is to allow the management of the heating power automatically by depending on the accessory used.

Finally, a final object of the present invention is to facilitate maintenance hot water and hot gas generators by providing them with devices allowing access to the state of the generator components without first disassemble the device.

The subject of the present invention is a device for regulating a generator of hot fluid in liquid or gaseous state which obviates the disadvantages existing systems and which allows all or part of the stated goals to be achieved previously. This regulation device is distinguished by the characteristics set out in claim 1.

The attached drawing schematically illustrates two embodiments of the device for regulating a generator of hot, liquid or gaseous fluid, depending on the present invention.

Figure 1 is a diagram illustrating the first embodiment of the regulating device.

Figure 2 is a partial longitudinal sectional view of a level of the liquid in the generator tank.

FIG. 3 is a diagram illustrating the second embodiment of the regulating device.

Figure 4 is a diagram illustrating for aluminum tanks and aluminum hooped on a stainless steel barrel the pressure curves as a function of time for regulation by pressure switch and temperature regulation according to the invention.

The first embodiment of the device for regulating a generator of hot fluid, in the liquid or gaseous state is illustrated diagrammatically in the figure.
1. The installation described with reference to the drawing relates to a steam generator supplying at will an iron or another accessory such as a steam cleaning device.

This installation includes a steam generator 1 for example, constituted like that described in document WO / 98/36215 but which can also have an aluminum tank only.

The installation also comprises a water tank 2, a pump 3 supplying the generator tank 1 in cold water, and an accessory for use 4, here an iron iron.

Pump 3 is supplied with cold water from water tank 2 and its outlet feeds the tank 1 of the steam generator. Between pump 3 and tank 1 is finds a water supply pressure relief valve 5 as well as a valve water depression 6.

A pressure switch 7 is located on the steam evacuation pipe 8 which includes a steam outlet solenoid valve 9 which supplies the iron 4 and which is manually controlled by the user using a switch 10 included in the iron 4.

The installation also includes an electronic control unit 11. This electronic control unit 11 regulates the water supply to the tank 1 by the pump 3 depending on the water level detected in the tank by a sensor level 12.

The tank 1 comprises a heating body 13 whose electrical supply is controlled by the pressure switch 7, a safety thermostat 14 limits the maximum tank temperature 1.

For the system to work properly, cold water must be introduced into the tank 1 preferably in its part occupied by the gas and not by the liquid and especially it is necessary that this contribution of cold water is done by small successive quantities to avoid thermal shocks and variations in temperature of the liquid in the tank 1.

This regulation of the introduction of cold water by pump 3 into the tank is controlled by the control unit 11 according to the information which are provided to it by the level sensor 12. This level sensor must be very sensitive and able to detect variations in the water level in tank 1 of on the order of 1 to 3 mm, preferably 1 to 2 mm.

To allow such precise regulation of the tank water level a sensor has been developed which is illustrated in Figure 2.

This level sensor is fixed on the cover of the tank 1, approximately in its axis, and extends inside this tank 1. It includes a float formed by an aluminum barrel 15 closed by a cover 16 also in aluminum. This cover has an O-ring seal, in the example illustrated, and the rim 17 of the cover is cold crimped on the opening of the barrel 15 so as to obtain a perfect and lasting seal in condition of required temperature and pressure operation i.e. over 110 ° C and 3 to 6 bar pressure.

It is important that the lift of this float is high because its buoyancy is only slightly influenced by lime deposits which can be there train as the generator is used. A cylindrical barrel from 15 to 20 mm in diameter and 40 to 60 mm in length suitable for envisaged applications.

The seal between the cover 16 and the barrel 15 is preferably an O-ring seal silicone with a hardness of 45 to 70 shore.

The cover 16, forming with the barrel 15 the float, has at its end away from the barrel 15 a blind tubular part 18, the end part of the wall has a bead 19. On this tubular part 18 of the cover 16 comes fit a flexible transparent silicone tube 20 with a hardness of the order of 45 to 70 shore and able to withstand a service temperature between - 60 to + 200 ° C. A stainless steel clamp 21 fixes this tube 20 to the tubular part 18 of the cover in leaktight manner.

The other end of the tube 20 is fitted onto the tubular part 22 of a end piece 24 and is clamped there by a second stainless steel flange 23. This end piece 24 has a through passage, its free end is provided with a six pan 25 and its middle part 26 is provided with a thread intended to be screwed into a tapped hole in the cover of the generator tank. A seal 28 seals. Thus, in the operating position, the level sensor is arranged inside the tank, approximately along the longitudinal axis thereof, and is connected to the cover of the generator tank by a flexible tube 20.

An angular switch, for example a mercury switch M is housed and fixed in the tubular part 18 of the float cover 15,17 and its wires conductors extend through the tube 20 and the end piece 24 to exit the tank 1 and be connected to the electronic control unit 11.

Such a level sensor is very precise, it makes it possible to detect level differences in the tank of the order of 1 to 3 mm, it is very reliable and very long, particularly due to the high lift of the float. Moreover, this sensor can be removed from the generator tank 1 simply by unscrewing the end piece 24, without the cover of the tank 1 having to be removed. So in if necessary a standard exchange of the sensor is easily carried out.

Thanks to this very sensitive level sensor, the regulation of the water level at the interior of the tank 1 is done by successive cold liquid introductions of small quantity avoiding any interference or temperature variation in the tank, the volume of liquid introduced being small compared to the volume of liquid contained in the tank. In addition, the introduction of cold water into the tank is done in the part of it containing vapor or gas, which also reduces disturbance caused by calcium carbonate.

Also thanks to this very sensitive level sensor, it is possible to generator operation to keep the energy of the energy practically constant pressure stored in the tank since the distribution of the volume of water and steam remains practically constant during operation.

This precise regulation of the water level therefore guarantees stable operation of the steam generator.

The regulation device object of the invention also allows management automatic electrical heating power delivered to the heater 13 of tank 1 depending on the accessory used, for example iron or steam cleaning device.

To this end, the accessory 10 is, when it is connected to the generator, connected to the electronic control unit 11 by an electrical conduit 27 delivering to this unit identification information for accessory 10. This information identification automatically control the electrical power delivered to tank heating body.

In this way you can get the maximum efficiency from the device in all its applications. This feature allows you to continuously take advantage of all installed electrical power. Automatic recognition of the accessory used by the electronic control unit also prevents any risk of overconsumption.

The electronic control unit therefore comprises a management module 28 the introduction of water into the generator tank controlled by the level, as well as a module 29 for managing the power delivered to the corps of tank heating controlled by the accessory coupled to the generator.

In a variant, the electronic control unit also includes a test module 30 comprising at least one counter totaling the running time of the generator. It is thus possible to obtain information at any time intended for the user or which may be useful for maintenance. Thanks to this running time counter it is possible to communicate to the user or to the maintenance service that it is time to carry out maintenance on the generator, for example its descaling, to maintain its efficiency and reliability at maximum level. In addition to this operating time counter of the generator, the test module may include circuits delivering information on the status of the main components of the generator, such as heater, float, water level alarm, pump, etc.

So by connecting the test module to a BC test bench, the service can immediately know the condition of the generator components and easily and quickly detect a fault.

The electronic control unit obviously includes a module supply of electrical energy 31.

For generators of higher power regulation by pressure switch, either a pressure control inside the tank, presents a significant drawback. Due to the thermal inertia of the heating bodies and the generator tank when the set pressure is reached and cut off the supply of the heating bodies, the rise in temperature and pressure of the water and steam in the tank continues.

The curves a and b in FIG. 4 illustrate this excess pressure, or pressure increase due to the thermal inertia of the generator. For a tank in aluminum, this increase in pressure is of the order of 0.7 bar (curved), while for a mixed stainless steel tank lined with aluminum (curve b) this increase in presslon can reach 1 bar. This type of regulation constant pressure therefore generates unacceptable exceedances of the value of setpoint as soon as the installed power is large. The energy stored in the mass of the generator creates a pure delay and causes these overshoots of the setpoint.

The present invention in its second embodiment relates to a regulation by slaving of the temperature of the generator tank which allows, as seen in Figure 4, curves c and d, to reduce the overshoot pressure at around 0.3 bar for aluminum tanks and 0.4 bar for mixed aluminum and stainless steel tanks.

Such a device for regulating by controlling the temperature of the tank is illustrated in FIG. 3. The generator comprises a tank 1, a water tank 2, a pump 3 and an accessory, iron 4 or cleaning nozzle 4a. Tank 1 is equipped with a level sensor 12 as described above with reference in Figure 2. This generator comprises in this embodiment two heating bodies 13 and 13a.

The electronic control unit comprises in this embodiment a display block 32, a power block 33 and a logic board 34.

As in the first embodiment, the logic card 34 includes a module for managing the introduction of water into the tank controlled by the float 12 and a water level detector in the water tank, as well as a water management module the power delivered to the heating bodies controlled by the accessory coupled to the generator.

This logic board 34 also includes a test module which can be connected to a test bench shown here by an interface and a PC 35.

In this embodiment the logic board 34 of the electronic unit of control also includes a body supply regulation module heating 13,13a. This module is controlled by a thermistor 36 which measures the temperature variations of the tank 1. This module for regulating the heater establishes a sampling of the temperature measurement to determine the slope of the temperature curve as a function of time. This image is necessary to regulate the tank. The temperature control is obtained by through a PID regulator (proportional, integrator, and differentiator) which integrates the optimal system parameters and considers the state of the outlet valve of the fluid. Thus we integrate the thermal inertia of the generator in the regulation, which allows more stable operation and lower pressure overruns.

Thus, by means of a thermistor of the type NTC (negative thermical characteristics) for example, we can get a picture of the thermal evolution of the system which allows according to a logic integrated in the card electronics to adjust the heating power as best as possible to limit overshoot of the set pressure. So by regulating the power of heating according to the evolution of the temperature of the tank, it is possible anticipate and limit pressure build-up, which is not possible with regulation controlled by a pressure switch operating all or nothing for a given pressure.

It should also be noted that in order to be able to regulate the level of water in the tank and the supply of the heating bodies from measurements temperature measured on the tank, this tank must maintain a orientation given throughout the life of the generator. To avoid any malfunction of the electronic control unit or the electronic card still has a trim detector that puts the generator in safety if the tank does not occupy its preset operating position.

Claims (12)

Device for regulating a generator of a hot fluid in the liquid state or gaseous comprising a tank provided with at least one heating body, a cold fluid supply pump, and at least one accessory supplied by the hot fluid leaving the tank, characterized in that this control device includes a liquid level sensor present in the tank comprising a float connected by a flexible tube to a nozzle passing through sealing the cover of the tank; by the fact that an angular switch is housed in the immediate vicinity of the float, its electrical conductor leaving the tank through said flexible tube and by the fact that it comprises a electronic control controlling the switching on and off of the pump from the data delivered by the level sensor. Device according to claim 1, characterized in that the unit control electronics include a pan trim detector causing the generator to shut down if this tank does not occupy its normal operating position. Device according to claim 1 or claim 2, characterized by the fact that the electronic control unit still has a module for regulation of the electric power delivered to the heating bodies according to the accessory which is connected to the generator. Device according to claim 3, characterized in that when connects the accessory to the generator of the identification information of the accessory are delivered to the electronic control unit which regulates function of these identification information the heating power of the tank. Device according to one of the preceding claims, characterized by the electronic control unit still has a test module comprising at least one generator running time counter. Device according to claim 5, characterized in that the module test is likely to deliver information to a test bench on the generator operating time and condition of its components main. Device according to one of the preceding claims, characterized by fact that it still has a thermistor measuring the temperature of the tank and by the fact that the electronic control unit includes a module for regulation of the supply of the heating bodies establishing a signal, proportional to the temperature variation of the tank over time, signal account of the thermal inertia of the tank and controlling the electrical supply of tank heating body. Device according to one of claims 1 to 6, characterized in that that it includes a pressure switch controlling the supply of the heating bodies of tank. Device according to claim 1, characterized in that the float of the level sensor is formed by an aluminum barrel, the neck of which is closed by a aluminum cover crimped on a silicone gasket surrounding the neck of the barrel. Device according to claim 9, characterized in that the tube flexible connecting the float to the tip is silicone. Device according to claim 9 or claim 10, characterized by the fact that the angular switch is a mercury switch. Device according to claim 1 or one of claims 9 to 11, characterized by the fact that the float lift is high, the weight of the tartar deposited on this float during the lifetime of the generator being negligible by in relation to this lift.

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