DE102011006766A1 - Steam generator for ironing station, has steam boiler, level sensor for measuring water level in steam boiler, water supply to fill steam boiler with water and control device for controlling water supply depending on signal of level sensor - Google Patents

Abstract

The steam generator (2) has a steam boiler (5), a level sensor (6) for measuring the water level in the steam boiler, a water supply to fill the steam boiler with water and a control device (12) for controlling the water supply depending on the signal of the level sensor. The control device has a timing element (13) for controlling the water supply. The timing element is so designed that the filling process ends latest after lapse of a predetermined time interval.

Description

Field of the invention

The present invention relates to a method for controlling a water supply of a steam generator to fill a steam boiler of the steam generator with water. It also relates to a steam generator with a steam boiler, a level sensor for measuring the water level in the boiler, a water supply to fill the boiler with water, and a controller for controlling the water supply in response to the signal of the level sensor. Finally, the invention relates to an ironing station with such a steam generator.

Background of the invention

For example, from the European patent specification EP 1 311 786 B1 discloses a household appliance for generating steam, comprising a boiler with a heating source for evaporating water and a control means with a setting means for adjusting the vapor pressure in the boiler. Further, a steam supply means is provided which cooperates with the adjusting means for adjusting the pressure in the boiler so that the heating source is turned on and off in response to the steam supply means being opened and closed. The boiler is filled by means of a pump from a reservoir with water. The pump is controlled by a temperature sensor, which, based on the measured temperature, allows a conclusion as to whether water must be topped up.

The German patent DE 196 145 11 discloses a steam ironing station with a steam iron and a steam station, the latter in turn having a steam generator. The steam generated in the steam generator is passed through a steam line in the steam iron, where it passes through a steam guide to the heating plate heated by a heater and exits there. The steam generator is filled by means of a feed pump via a water pipe from a water tank.

Finally, the German Offenlegungsschrift discloses DE 4 308 941 A1 an arrangement for hot water, which can be operated with a timer controlled in an operating condition with and in an operating condition without a circulation function. When operating with circulation function, an NTC sensor monitors the temperature in a circulation circuit and keeps it constantly at a predetermined level. For this purpose, a hot water installation with its taps is connected to a water switch with Venturi nozzle of a gas wall device of any design on the output side of the transit memory. After the taps, a safety thermostat is arranged on a circulation line following the taps, which is connected to a control device with a subsequent timer.

The problem underlying the invention

The invention has for its object to provide a comparison with the prior art improved method for controlling a water supply of a steam generator to pump water into a steam boiler of the steam generator. Next, an improved steam generator to be provided with a steam boiler. Finally, an improved. Ironing station can be provided with such a steam generator. In particular, it should be achieved that the vapor pressure in the steam generator does not drop excessively by refilling water. The solution should be reliable and easy to implement at low cost.

Inventive solution

The reference numbers in all claims have no limiting effect, but are only intended to improve their readability.

The solution of the object is achieved by a method for controlling a water supply of a steam generator with the features of claim 1. It is controlled by means of a timer, the water supply so that the filling of the boiler of the steam generator ends at the latest after a predetermined first period of time. In other words, when the first period has elapsed, measured from the beginning of the filling, the filling operation is ended. By this measure, the amount of water supplied per filling process is limited, taking advantage of the fact that the amount of water is substantially proportional to the filling. The limitation on the amount of filling may limit the cooling caused by the refilled water, which may advantageously prevent excessive pressure drop in the boiler caused by the cooling.

The feature that the filling process ends "at the latest" after the expiration of the predetermined first time period is to be understood such that the expiration of the time duration is a sufficient condition for the termination of the filling process. In any case, if the first period of time has expired, the filling process ends, irrespective of other factors, eg. B. the level. On the other hand, but not yet expired first time quite other factors, such. B. the level, trigger an end of filling.

The object is further achieved by a steam generator with the features of claim 7. The steam generator according to the invention has a timer which can control the water supply. Thus, by controlling the water supply, the filling operation can be easily stopped after the lapse of the predetermined first period of time. A steam generator is understood to mean a system for providing and / or delivering steam in order to be able to treat a material to be steamed with the steam. For this purpose, the steam generator generates a Dampfaustoß. The steam can z. B. are used to care for clothing and this z. B. part of an ironing device, an ironing station, a Dampfglätters, a so-called steam brush or a steam brush. The steam can also be used for cleaning purposes and this z. B. be part of a steam cleaner.

In particular, the invention task is also solved by an ironing station with the features of claim 15, which is thus equipped with the steam generator according to the invention. The ironing station is therefore a steam ironing station. Especially in an ironing station, to ensure a uniform treatment of the ironing material, it is essential that the steam pressure for steam ironing is kept substantially constant. The method according to the invention and the steam generator according to the invention can therefore be used particularly advantageously in an ironing station.

Preferred embodiment of the invention

Advantageous embodiments and developments, which can be used individually or in combination with each other, are the subject of the dependent claims.

In a preferred method according to the invention and a preferred steam generator according to the invention, the water supply is also controlled by means of a level sensor. This is preferably done in such a way that the steam boiler is filled only when the level sensor signals that it falls below a predetermined level limit. In other words, if the undershooting of the fill level limit value is no longer signaled, the filling process is ended, irrespective of whether the predetermined first time duration has already expired or not. The reporting of an undershoot is a necessary, but not sufficient condition for the filling process, because according to the invention, the filling is completed regardless of the level even after a predetermined time.

The preferred level sensor only signals whether the level limit has been reached or not. So if no falling below the level limit is signaled, this is equivalent to signaling the reaching or exceeding of the level limit. In this context, it should be noted that the signaled level does not necessarily have to match the actual level in the boiler. This is due in particular to the inertia and / or hysteresis that almost every level sensor has. Thus, it can be displayed during the filling process falls well below the level limit, although the level limit has been reached by filling in the meantime already or even exceeded. It is an achievable advantage of the invention that an excessive filling caused by such inertia and / or hysteresis is prevented by the fact that the filling process also ends after the expiry of the predetermined first period of time.

In a preferred embodiment of the invention, the water supply is further controlled such that after a predetermined second period of time commences from the time when the timer is stopped by the timer, filling of the boiler begins again, if or as soon as the level sensor falls below the level limit reports. With this embodiment of the invention is thus achievable that the steam boiler, as far as the level limit is not reached after the last filling or in the meantime has fallen below again, is refilled. By the second period of time it is ensured that the two Befüllvorgänge far enough apart to avoid excessive cooling and an associated excessive drop in the vapor pressure. Furthermore, the inertia of the level sensor can be compensated by the second time period by the level sensor is given sufficient time to signal the correct level. As a result, overfilling of the boiler can be prevented.

Preferably, the water supply is controlled by means of the timer such that each started after the second period of time filling ends at the latest after the expiry of the first period of time. This means that as long as the level sensor signals a drop below the predetermined level limit, a repetitive filling cycle is performed, in which filling intervals with the length of the first time duration and Nichtbefüllintervalle with the length of the second time duration alternate steadily. Preferably, this cycle ends only when the level sensor no longer signals that it falls below the level limit.

The second time period is preferably at least one second, more preferably at least two seconds, more preferably at least three seconds, especially preferably at least four seconds, e.g. B. about five seconds. The preferred second time period is at most one minute, preferably at most 30 seconds, particularly preferably at most 15 seconds, particularly preferably at most 10 seconds, particularly preferably at most 7 seconds. B. about five seconds.

The preferred first time period is preferably at least half a second. It is particularly preferably at least one second, more preferably at least two seconds, z. B. about three seconds. The preferred first time is less than 30 seconds, more preferably less than 15 seconds, most preferably less than nine seconds, most preferably less than six seconds.

In a preferred steam generator, the level sensor is operatively connected to the timer to control it. As a result, it can be achieved that the fill level sensor triggers the measurement of the first time duration with a signal from the fill level sensor which signals that the value falls below the predetermined fill level limit value. The timer, in turn, may then control the supply of water to start filling substantially simultaneously with the signaling of the fill level violation and to terminate upon expiration of the first duration. For this purpose, the timer preferably controls a power supply of the water supply.

The preferred level sensor is a temperature sensor. It is exploited that the wall temperature of the boiler near the heating element is lower when there is water, as in the absence of water, because the water can cool the wall. An increase in the temperature measured by the temperature sensor can therefore be interpreted as an indication of a falling below the level limit. In a preferred fill level sensor, reaching or exceeding a first temperature limit value is counted as falling below the fill level limit value. A reaching or falling below a second temperature limit is considered a. Reaching or exceeding of the level limit is evaluated. In this case, the second temperature limit value is preferably lower than the first temperature limit value. Typically, the two limits are between one and five degrees Celsius (degrees Celsius) apart, e.g. B. by two ° C. The preferred temperature limits are above 110 ° C. The first temperature limit can, for. B. at 155 ° C and the second at 123 ° C. Due to the distance between the two limit values, a hysteresis is achieved in the fill level sensor in order to avoid fluttering of the fill level sensor signal.

The water supply can, for. B. be a pump or a valve. Particularly preferably, it is an electrically driven pump or an electrically controllable valve. The preferred control device comprises a relay or a semiconductor switch for controlling the water supply. A particularly preferred semiconductor switch is a semiconductor power switching element, for. B. a Tyristor or a triac. The preferred control device is an electronic control device. You can z. Example, a microelectronic logic circuit or a microprocessor. The microelectronic circuit or the microprocessor can actuate the relay or the semiconductor switch.

A preferred steam generator has a reservoir for holding water. The water supply preferably connects the reservoir to the boiler to pump water from the reservoir into the boiler. Usually, the water supply, so z. As the pump or valve, connected by line pieces to the reservoir on the one hand and the boiler on the other.

The preferred steam generator also has a heating element for heating the steam boiler. Furthermore, a sensor for controlling the heating element is preferably provided. The sensor preferably measures a property of the steam in the boiler, e.g. B. the vapor pressure or the steam temperature. This can help to ensure a constant pressure within the boiler within the required limits.

Brief description of the drawings

Further advantageous embodiments will be described in more detail below with reference to an embodiment shown in the drawings, to which the invention is not limited.

They show schematically:

1 an ironing station according to the invention with a steam generator according to the invention and an iron; and

2 a conceptual representation of the control method according to the invention.

Detailed description based on an embodiment

In the following description of a preferred embodiment of the present invention, like reference characters designate the same or similar components.

The embodiment will be described below with reference to the 1 and 2 explained. It is in 1 a steam ironing station 1 shown for steam ironing an ironing board, which is a steam generator 2 and an iron 3 having. The iron 3 is over a steam line 4 through which one of the steam generator 2 generated steam blast to the iron 3 is directed, with the iron 3 connected. The steam generator 2 includes a steam boiler 5 , a level sensor 6 and a water supply in the form of an electric filling pump 7 , The filling pump 7 connects the boiler 5 over filling lines 8th . 9 with a storage container 10 in the water 11 is held, so that the filling pump 7 the boiler 5 if necessary, new water 11 from the reservoir 10 can supply.

To control the filling pump 7 is a control device 12 provided, on the one hand with the level sensor 6 and on the other hand with the filling pump 7 electrically connected. The control device 12 has a timer 13 on. The timer 13 is so in the controller 2 arranged on the one hand with the level sensor 6 is functionally connected to be controlled by him, and on the other hand with the pump 7 is functionally connected to control these. The timer is part of a microelectronic circuit of the control device, which controls a power switching element in the form of a tyristor to the power supply to the electric filling pump 7 to regulate and thus the pump 7 switch on or off. By switching the pump on and off 7 will be filling the boiler 5 with water 11 from the reservoir 10 started or stopped. The microelectronic circuit includes a microprocessor and the timer is implemented by a control program executed with the microprocessor.

Next, the steam generator has an electric heating element 14 for heating the boiler 5 on and a pressure sensor 15 for controlling the heating element 14 , The pressure sensor 15 controls the heating element via an electronic control circuit, not shown in such a way that it falls below a predetermined minimum pressure, the heating element 14 switched on and when exceeding a prescribed maximum pressure, the heating element 14 is turned off. This has the purpose of a substantially constant vapor pressure in the boiler 5 to make sure. Via a steam valve 16 and the steam line 4 the steam gets to the iron 3 over there over the soleplate 17 to be delivered to the ironing. Especially when ironing is a constant vapor pressure of particular importance to achieve a uniform ironing result.

If over the steam valve 16 Steam to the iron 3 is discharged, it is water in the boiler 5 consumed. At the latest, when the water level in the boiler 5 falls below a certain minimum, water must 11 from the reservoir 10 be refilled. On the one hand, the fill level sensor serves this purpose 6 , the controller, the falling below a level limit 18 can signal, and the filling pump 7 that the boiler 5 in such a case water 11 from the reservoir 10 can supply.

However, there is a fundamental risk that the refilling of water due to its lower temperature, the temperature in the boiler 5 decreases and thereby also the vapor pressure in the steam boiler 5 falls below a desired minimum value. According to the invention this is prevented by the fact that the duration of the filling process, and thus the amount of the from the reservoir 10 supplied water, by means of the timer 13 is limited.

The control method that in the control device 12 is carried out in 2 conceptually presented. A first binary logic element 19 assumes a value that is from the level sensor 16 is determined. This is through the first Steurpfeil 20 symbolizes. The first binary logic element 19 is as a memory cell in the control unit 12 realized. When the level sensor 6 falling below the level limit 18 signals, the first logic element takes a first of two possible values (hereinafter referred to as "closed" for reasons of clarity), in the other case, the second value (hereinafter referred to as "open"). The first logic element 19 controls as by the second control arrow 21 symbolizes, the timer 13 at. This in turn controls, as by the third control arrow 22 symbolizes, a second binary logic element 23 , in turn, as a memory cell in the control unit 12 is realized.

If the first logic element 19 Switching from "open" to "closed" switches the timer 13 the second logic element 23 in the state "closed". At the same time it begins to measure the elapsed time and switches the second logic element 23 after the first period of 3 seconds has elapsed, the logic state "open". After a second period of 5 seconds, it switches the second logic element 23 again in the state "closed", after a further first period on in the state "open" and so on, always alternating.

The series connection of the logic elements 19 and 23 in 2 should symbolize that the two logic elements for controlling the water supply are "and" -connected: Only if both logic elements 19 . 23 in the state "closed" are the filling pump 7 set in motion to the steam boiler 5 with water 11 from the reservoir 10 to fill. This will ensure that the steam boiler 5 on the one hand only filled when the level sensor 6 falling below the level limit 18 and also that the fill duration never exceeds the predetermined first time duration. Due to the timer-controlled second logic element 23 , which repeatedly switches between the state "closed" in the state "open", the filling pump 7 at "closed" first logic element 19 Continuously switched on and off, until the level sensor indicates no falls below the level limit more and therefore the first logic element 19 from the state "closed" to the state "open". In this case, the power supply to the filling pump 7 interrupted and no further infestations takes place. Only when from the level sensor 6 again falls below the level limit 18 is signaled, the state of the first logic element changes 19 back in "closed" and the timer 13 begins, as described above, with the measurement of the first time duration and the corresponding control of the second logic element.

The heating element 14 runs spirally in the lower half of the boiler 5 on the boiler wall. In the figure, the boiler wall area in which the spiral lies, shown schematically hatched. The level sensor 6 is a temperature sensor that is near the heating element 14 is arranged and the wall temperature near the heating element 14 measures (not shown in the schematic figures only). When measuring the level with the temperature sensor, use is made of the fact that the wall temperature of the steam boiler near the heating element is higher when there is no water there than in the case of existing water. From this temperature difference can be concluded on the level. When falling below the level limit 18 is the heating element 14 not covered by water for a short time before the water level in the boiler 5 is raised again by the described filling.

With the invention can be advantageously achieved that the vapor pressure in the boiler 5 of the steam generator 2 is not excessively lowered by adding water. The solution works reliably and can be implemented with simple means at low cost.

The features disclosed in the foregoing description, the claims and the drawings may be of importance both individually and in any combination for the realization of the invention in its various forms.

LIST OF REFERENCE NUMBERS

1

ironing station

2

steam generator

3

Iron

4

steam line

5

steam boiler

6

level sensor

7

filling pump

8th

filling line

9

filling line

10

reservoir

11

Water in the storage tank

12

Control device timer

14

heating element

15

pressure sensor

16

steam valve

17

soleplate

18

level limit

19

First logic element

20

First control arrow

21

Second control arrow

22

Third control arrow

23

Second logic element

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1311786 B1 [0002]
• DE 19614511 [0003]
• DE 4308941 A1 [0004]

Claims (15)

Steam generator with a steam boiler ( 5 ), a level sensor ( 6 ) for measuring a water level in the steam boiler ( 5 ), a water supply to the steam boiler ( 5 ) to fill with water, and a control device ( 12 ) for controlling the water supply in dependence on the signal of the level sensor ( 6 ), characterized in that the control device also comprises a timer ( 13 ) for controlling the water supply. Steam generator according to claim 1, characterized in that the level sensor ( 6 ) with the timer ( 13 ) is connected to control it. Steam generator according to claim 1 or 2, characterized in that the level sensor ( 6 ) is a temperature sensor. Steam generator according to one of claims 1 to 3, characterized in that the water supply to an electrically driven pump ( 7 ) or an electrically operable valve and the control device ( 12 ) comprises a relay or a semiconductor switch for controlling the water supply. Steam generator according to claim 4, characterized in that the control device ( 12 ) comprises a microelectronic circuit for actuating the relay or the semiconductor switch. Steam generator ( 2 ) according to one of claims 1 to 5, characterized in that the steam generator ( 2 ) a storage container ( 10 ) and the water supply to the reservoir ( 10 ) with the steam boiler ( 5 ) to transfer water from the reservoir into the boiler ( 5 ) to transport. Steam generator ( 2 ) according to one of claims 1 to 6, characterized in that the steam generator ( 2 ) a heating element ( 14 ) for heating the steam boiler ( 5 ) having. Steam generator ( 2 ) according to claim 7, characterized in that the steam generator ( 2 ) a sensor ( 15 ) for controlling the heating element ( 14 ) having. Ironing station ( 1 ) with a steam generator ( 2 ) according to one of claims 1 to 8. Method for controlling a water supply of a steam generator ( 2 ) to a steam boiler ( 5 ) of the steam generator with water ( 11 ), characterized in that the water supply by means of a timer ( 13 ) is controlled such that the filling of the boiler ( 5 ) ends at the latest after a predetermined first period expires. A method according to claim 10, characterized in that the water supply by means of a level sensor ( 6 ) is controlled such that the steam boiler ( 5 ) is filled only when the level sensor ( 6 ) falls below a predetermined level limit ( 18 ) signals. Method according to claim 10 or 11, characterized in that the water supply by means of the timer ( 13 ) is controlled in such a way that, after a predetermined second period of time has elapsed from the time of completion of the filling by the timer ( 13 ) begins to refill the boiler ( 5 ) starts when or as soon as the level sensor ( 6 ) falls below a predetermined level limit ( 18 ) reports. A method according to claim 12, characterized in that the water supply by means of the timer ( 13 ) is controlled in such a way that each filling begun after the second time has expired ends at the latest after the expiry of the first time periods. A method according to claim 12 or 13, characterized in that the second period of time is at least 1 second. Method according to one of claims 10 to 14, characterized in that the first time period is at least half a second.

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