WO2014095975A2

WO2014095975A2 - Steam generator with water level detection device

Info

Publication number: WO2014095975A2
Application number: PCT/EP2013/077054
Authority: WO
Inventors: Nicolas Chabut
Original assignee: BSH Bosch und Siemens Hausgeräte GmbH
Priority date: 2012-12-19
Filing date: 2013-12-18
Publication date: 2014-06-26
Also published as: WO2014095975A3

Abstract

The invention relates to a steam generator (11), comprising an evaporator tank (12), a heating device (21) for heating water (w) present in the evaporator tank and a water level detection device (38), wherein the water level detection device (38) comprises a boiler overflow (19) which is connected to the evaporator tank (12) and leads to at least one liquid sensor (35) of the water level detection device (38).

Description

Steam generator with water level detection device

The invention relates to a steam generator for a domestic appliance, comprising an evaporator vessel, a heating device for heating water in the evaporator vessel and a water level detecting device. The invention also relates to an electrically operated domestic appliance, in particular steam cooking appliance, with such a steam generator.

It is a Dampfgargerät known, in which a level sensor is disposed in the heated evaporator vessel. However, a high water temperature and a formation of steam and boiling, bubbles forming water are a problem in reliably detecting a water level (also referred to as level or level).

There is also known a steam cooker in which an amount of water in the evaporator vessel is estimated from the amount of water introduced using a pump and a solenoid valve for supplying water to an evaporator vessel of the steam generator. However, the accuracy of the estimation is comparatively low, e.g. due to only imprecisely determined flow rates through the solenoid valve and only vaguely known evaporation performance.

It is also known a Dampfgargerät without a water level detection. In doing so, the water tank from which water is supplied must be sealed.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art. In particular, it is the object to design a steam generator of the type mentioned in such a way that a reliable operation of the water level detection device is made possible. In particular, a functionality should be ensured even with boiling water and implemented with simple means.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims. The object is achieved by a steam generator, comprising an evaporator vessel, and a heater for heating water in the evaporator vessel and a water level detecting device, wherein the water level detecting means connected to the evaporator vessel overflow (hereinafter referred to as "boiler overflow"), which at least one Liquid sensor of the water level detection device leads.

Because the liquid sensor of the water level detection device is arranged outside the heatable evaporator vessel, it is not directly exposed to boiling bubbles or steam and, moreover, can be accommodated in a region having a comparatively low temperature. Alone already this results in a more reliable determination that a certain water level (the height is determined by the boiler overflow) has been achieved in the evaporator vessel. The water level detection device is thus in particular adapted to determine by means of the liquid sensor reaching or exceeding a predetermined by the height of the boiler overflow in the evaporator vessel water level. It is another advantage that various liquid sensors can be used.

The steam generator or the evaporator boiler can operate pressurized or depressurized. also called steam generating tanks. The evaporator vessel can be filled with water, for example, by opening a water supply valve. The water supply valve may be, for example, a solenoid valve.

The boiler overflow may in particular be a pipe or a pipe which, in particular initially in a lateral direction, is led out of the evaporator vessel. The boiler overflow can also be a breakthrough through a wall of the evaporator boiler in the simplest embodiment.

It is an embodiment that the steam generator is a boiler. A boiler typically has the evaporator vessel, in which water is insertable, and at least one heating device, wherein the heating device is designed for heating the standing in the evaporator vessel water for generating steam. A boiler has the advantage of a high water volume and a simple construction. According to a development, an upper region of the evaporator vessel is designed as a vapor container, wherein the upper region in particular has a vapor outlet on the upper side.

Alternatively, the steam generator may be a water heater, in particular with a sloping or vertical flow pipe as the evaporator boiler.

It is a development that the liquid sensor is a sensor which detects a presence of water, e.g. a humidity sensor. With a liquid sensor, a presence of water can be detected in particular in or behind the process, if necessary, only from a predetermined amount or concentration. As a result, overflow can be detected particularly sensitively and quickly, even in small quantities.

It is still a development that the liquid sensor is a flow sensor. With a flow sensor, a flow rate of water can be determined by the flow, if necessary, only from a predetermined volume. It is also a development that the liquid sensor is a level sensor. Such a sensor is particularly simple, inexpensive and robust ausgestaltbar. The type of flow sensor is not limited and may be e.g. have a float, e.g. as part of a reed contact. It is a further embodiment that the boiler overflow leads into a measuring container. This has the advantage that an even calmer measuring environment is provided for a liquid sensor, in particular if the liquid sensor is located in or on the measuring container. A measuring container, in particular in combination with a level sensor, enables a reliable yet robust detection of an overflow of the evaporator vessel.

It is a development that the measuring container directly to the evaporator vessel (eg separated only by a breakthrough in the wall of it) or shortly next to the Evaporator boiler is arranged. This allows a comparatively short reaction time.

It is still a further development that a line is connected to the boiler overflow or the boiler overflow has a line leading to the measuring container. This results in the advantage that the water can cool as it flows through the line and at least smaller amounts of water can get into the measuring container without any surges. According to a development of the measuring container is lower than the evaporator vessel. This allows the water from the evaporator boiler to flow unhindered and with sufficient speed in the measuring container.

It is still an embodiment that the measuring container has a first part of the container, in which the boiler overflow (possibly via a coming from this boiler overflow pipe) opens, and that the measuring container has a second sub-container, is arranged on (including in) the liquid sensor , By means of the separation of the measuring container into two partial containers, the water in the second partial container can be calmed even further, which further promotes measurement accuracy and robustness of the measurement.

It is yet another embodiment that the first sub-container and the second sub-container are connected to each other by a further overflow (hereinafter referred to as "measuring container overflow") and the liquid sensor designed as a level sensor detects a water level in the second sub-container ensures that turbulences or water level fluctuations that occur when excess water is introduced into the first part container are not transferred to the second part container, or only to a small degree, thus making detection of an overflow of water even more reliable and free of disturbances recognized the evaporator boiler.

In other words, in the steam generator according to this embodiment, there are two overflows. The first overflow serves as a boiler overflow from the evaporator vessel of the actual steam generator out into the first part container of the measuring container. The second overflow serves as a measuring tank overflow to allow water to overflow the first sub-container of the measuring container in the second sub-container. Thus, it is doubly utilized that an overflowing or inflowing water only produces a slight disturbance in the following container and thus a water surface is calmer in the respectively subsequent container than in the previous container. This is especially true if the first sub-container and the second sub-container are arranged side by side.

Alternatively, the first sub-container and the second sub-container may be fluidly connected to one another, for example, according to the principle of the communicating tubes. Also, e.g. the liquid sensor is a flow meter associated with the second sub-tank, etc. This can be located for example in the measuring tank overflow and detect a water passage through the measuring tank overflow.

For ease of manufacture and placement, the first sub-container and the second sub-container can be made integral with each other. However, the first sub-container and the second sub-container may also be arranged separately from each other, e.g. be connected to each other via an overflow pipe.

It is an embodiment of the fact that the first sub-container is filled with water during operation of the steam generator. This may in particular always arise after a first overflow of water from the boiler overflow. A water column located in the first sub-tank is sluggish so that the liquid sensor is not already at e.g. Passage of steam or small sloshing through the boiler overflow amounts of water strikes. For a first start-up, the first sub-container may e.g. previously filled sufficiently with water or it is filled according to longer and more water in the evaporator vessel and through the boiler overflow in the first part of container until the water column has built up.

It is also an embodiment that the boiler overflow of the evaporator boiler (or the coming of this boiler overflow line) leads to a lower portion of the first part container. Since the first sub-tank is filled with a water column during operation, the line leads into the water in the first sub-tank and does not drip into it. This prevents oscillation of the surface of the water column and assists accurate detection. It is also an embodiment thereof that the second sub-container has a (in particular ground-level) throttled water outlet through which therefore only a predetermined limited or limited amount of water can escape, for example in a storage tank or catch basin. A flow cross-section of the throttled water outlet can be made so small that it allows only a small volume flow. So runs a greater amount of water in the second part of the container, as it may occur when the boiler overflow on the evaporator vessel, the second part of the container can fill and strike the associated liquid sensor. Through the water outlet, the water in the second part of the container can flow out slowly again, so that the liquid sensor can strike again in a subsequent overflow of the evaporator vessel again. The flow cross-section of the throttled water outlet is thus so small that it allows a filling of the second sub-container in an overflow of the evaporator vessel (eg with open water supply valve) and yet so large that it sufficient emptying of the second sub-container between two opening intervals of the water supply valve allowed the evaporator boiler.

During operation of the steam generator, for example, the evaporator vessel may initially be filled with water. Upon reaching a water level in the evaporator vessel, which corresponds to a (geodetic) height of the boiler overflow, a large amount of water flows through the boiler overflow into the first sub-container of the measuring container. If this has not already been the case, the first part of the container fills up to the measuring tank overflow. When filled up to there first sub-container another water inlet causes water more or less directly overflows into the second sub-tank. The flow rate of the overflowing water is at least about the same as the flow rate supplied to the evaporator vessel and far higher than the flow rate which can be simultaneously discharged by the throttled water outlet of the second sub-tank. This also fills the second part of the container with water. The increase in the level in the second sub-tank is detected by means of the level sensor. In particular, a reaching or exceeding a predetermined threshold value of the fill level can be detected, whereupon the water supply to the evaporator vessel is interrupted. After interrupting the water supply flows, possibly with a slight delay, no more water in the measuring container, so that the water in the second sub-container flows through the throttled water outlet over the subsequent time. During this time, the second part container empties again (comparatively slowly). Should accidentally leak water from the evaporator boiler through the boiler overflow, so this is usually such a small amount that the previously dropped level sensor does not respond.

An evaluation of the sensor signals of the level sensor can be made in the steam generator or in a central control unit of the cooking appliance. Instead of the throttled water outlet and a valve can be arranged in a wall of the second part of the container, which valve has an adjustable opening and is controllable for discharging water from the second part of the container. According to a further development, such a valve can provide different settings, so that, for example, after detecting a water level by the liquid sensor and deactivating the water supply into the liquid container, the entire amount of water in the second part container can be discharged from it in as short a time as possible.

Another development is that the water outlet is formed by a pump which continuously pumps out a small amount of water from the second part of the container and optionally can pump out a larger amount per unit of time if necessary.

The object is also achieved by an electrically operated household appliance, in particular steam cooking appliance, with a steam generator as described above. The household appliance may have the same advantages as the steam generator and be designed analogously.

The steam cooker may be a stand-alone steam cooker or may be a combined appliance, e.g. a combination of oven or microwave oven and steamer.

Yet another embodiment is that a control device of the steam generator is configured to interrupt a water supply to the evaporator vessel, for example, at a predetermined measurement signal of the water level detection device to close a water supply valve for the evaporator boiler. As a result, no more water flows into the evaporator tank and consequently no more water through the boiler overflow into the measuring tank. To open the valve so that water flows back into the evaporator vessel, the connected controller or control device can provide, for example, that the water supply valve is opened again after a predetermined period of time or introduced heating power.

A development consists in that an outlet pump of the steam generator is designed to pump water from a storage tank into which water flowing from the water outlet of the second partial container passes. For example, such a pump may be activated in response to activation of the water level detection device to pump water out of the reservoir tank and thus set the measurement device in a start state for a next measurement cycle. The storage tank can also be part of the measuring container.

In the following figure, the invention will be described schematically with reference to an embodiment schematically. The figure shows sketched components of a steam generator with a water level detection device. The Fig. Shows a steam generator 1 1 of a household Dampfgargeräts 10 with an evaporator vessel 12. A heater 13, which is arranged in particular below the evaporator vessel 12, serves for heating water W, which is located in the evaporator vessel 12. The heater 13 may, for example, have a resistance heating tube. If necessary, new water W can be introduced into the evaporator vessel 12 through a water inlet 14 and a water supply valve 15 (eg, a solenoid valve) connected thereto. The water inlet 14 is arranged in particular on the underside of the evaporator vessel 12. By operating the heater 13, the water W is evaporated to steam d. The steam d can be passed through a steam outlet 17 to a component of the household steam cooking appliance in which it is needed, for example in a cooking chamber. At the beginning of an operation of the steam generator 1 1 or after a certain period of heating and removal of steam d via opening of the inlet valve 15 and the water inlet 14, water W is fed into the evaporator vessel 12 again. In order to ensure a maximum filling level of the water W in the evaporator vessel 12, a boiler overflow 19 is formed at a corresponding height in a side wall of the evaporator vessel 12. In particular, the boiler overflow 19 is dimensioned so that at least as much water W can run through it, as is maximally supplied through the water inlet 14. Excess water W thus flows over or through the boiler overflow 19 from the evaporator vessel 12 out. In order then to interrupt a water supply to the evaporator vessel 12 (by closing the water supply valve 15), the steam generator 1 1 has a water level detection device 38. This has in particular the boiler overflow 19 and a measuring tank 23 downstream of the boiler overflow 19 in which water W flowing out via the boiler overflow 19 flows in. The measuring container 23 is preferably arranged below the evaporator vessel 12, so that the water W can flow from the boiler overflow 19 by gravity into the measuring container 23.

The measuring container 23 has a first part container 22 into which a line 21 coming from the boiler overflow 19 leads. The line 21 preferably opens in a lower portion of the first sub-container 22. In the first sub-container 22 inflowing water W causes a water column in the first part of the container 22 is formed. The first sub-container 22 is separated by a wall 24 from a second sub-container 25, wherein an upper edge of the wall 24 forms a measuring container overflow 27. Alternatively, a passage opening through the wall 24 may serve as a measuring container overflow. If in the first sub-tank 22 the water column has reached the upper edge of the wall 24 (and thus a predefined height), the water W from the first sub-tank 22 into the second sub-tank 25 over. This leads to an increase in a water column or the water level or level in the second sub-tank 25. In normal operation, the first sub-tank 22 is usually filled up to the upper edge of the wall 24, since the water W can not run differently.

A liquid sensor 35 is arranged, in particular on or in the second sub-container 25, in such a way that it detects a water level in the second sub-container 25. When the water column in the second sub-tank 25 reaches a predetermined level or water level, the liquid sensor 35 is activated. The liquid sensor 35 is in particular a fill level sensor, for example a magnetic fill level sensor. For example, the level sensor may include a float located in the second sub-tank 25. have, which has a permanent magnet. Upon reaching a predetermined water level, the magnet of the float closes a located outside of the second sub-tank 25 reed contact. As a result, a sensor signal is output by the liquid sensor 35, which is transmitted to a control device 39 of the cooking appliance 10, for example. The control device 39 in turn can then close the inlet valve 15 and interrupt a water supply to the steam boiler 19. Consequently, if necessary after a certain time delay, no further water W flows more via the boiler overflow 19 and via the measuring container overflow 27 into the second partial container 25.

The second sub-container 25 also has a throttled water outlet 33. This can be in a simple embodiment, a (small) passage opening, which allows a limited outflow of water W (ie with low passage rate) from the second part of container 25 out. The water W flows from the second part container 25 either directly into a drain of the cooking appliance 10 or, as shown, into a storage tank 31. The storage tank 31 may represent a third sub-container of the measuring container 23 The throttled water outlet 33 is dimensioned so that less water W flows, in particular significantly less water W flows, as in an overflow of water W from the boiler overflow 19 and the measuring container overflow 27 in the second partial container 25 flows. This can ensure that an increasing water column in the second sub-tank 25 is achieved. If, on the other hand, only unwanted overflowing water W is led out of the evaporator vessel 12 into the measuring vessel 23, it is such a small amount of water that it can emerge substantially directly from the throttled water outlet 33, so that no or no significant change in the second part vessel 25 Increase in the water level is recorded and the liquid sensor 35 is not activated.

The storage tank 31 is in particular connected to a pump 37 in order to be able to discharge water W from it.

Of course, the present invention is not limited to the embodiment shown. In particular, the measuring container can also be arranged next to instead of at a height level below the evaporator boiler.

Furthermore, the moisture sensor need not necessarily be arranged physically within the second sub-container, but may be arranged so that it detects liquid in the second sub-container, for example, an optical level sensor.

LIST OF REFERENCES

10 home appliance

1 1 steam generator

12 evaporator boiler

13 heating device

14 water inlet

15 water supply valve

17 steam outlet

19 boiler overflow

21 line

22 first part container of the measuring container

23 measuring containers

24 wall

25 second sub-container of the measuring container

27 measuring tank overflow

31 storage tank

33 throttled water outlet

35 liquid sensor

37 pump

38 water level detection device

39 control device

Steam

W water

Claims

claims

Steam generator (1 1) for a household appliance (10), comprising a

Evaporator vessel (12) and a heating device (21) for heating water (W) located in the evaporator vessel (12) and a water level detection device (38),

characterized in that

the water level detection device (38) has a boiler overflow (19) connected to the evaporator vessel (12) which leads to at least one liquid sensor (35) of the water level detection device (38).

Steam generator (1 1) according to claim 1, characterized in that the steam generator (1 1) is a boiler.

Steam generator (1 1) according to one of the preceding claims, characterized in that the boiler overflow (19) leads into a measuring container (23).

Steam generator (1 1) according to any one of the preceding claims, characterized in that the measuring container (23) has a first part container (22) into which the boiler overflow (19) opens, and has a second sub-container (25) adjacent thereto, on which the liquid sensor (35) is arranged.

Steam generator (1 1) according to claim 4, characterized in that the boiler overflow (19) or from the boiler overflow (19) coming line (21) leads to a lower region of the first partial container (22).

Steam generator (1 1) according to claim 4 or 5, characterized in that the second part container (25) has a throttled water outlet (33).

Steam generator (1 1) according to one of claims 4 to 6, characterized in that the first part container (22) and the second part container (25) by a Meßbehälterüberlauf (27) are interconnected and the liquid sensor (35) detects a water level or a water flow in the second sub-tank (25).

8. steam generator (1 1) according to one of claims 4 to 7, characterized in that the first part container (22) during operation of the steam generator (1 1) with water (W) is filled.

9. Electrically operated household appliance (10), in particular Dampfgargerät, with a steam generator, characterized in that the steam generator is a steam generator (1 1) according to one of the preceding claims.

10. Domestic appliance (10) according to claim 9, characterized in that a control device (39) of the steam generator (1 1) is configured to interrupt a water supply to the evaporator vessel (12) at a predetermined measurement signal of the water level detecting means (38).